Review of Plutonium Oxide and Hanford Tank Farms Report

RPP-RPT-50941, Rev. 0

TABLE OF CONTENTS 1.0 2.0 EXECUTIVE SUMMARY .................................................................................................1 BACKGROUND INFORMATION ....................................................................................3 2.1 2.2 2.3 2.4 3.0 3.1 PROBLEM STATEMENT ......................................................................................3 PREVIOUS WORK 2010 WTP REPORT ...........................................................4 IMPACT OF 2010 WTP REPORT PISA ISSUED ..............................................5 PLUTONIUM OXIDE RESOLUTION PLANS .....................................................6 REPROCESSING FACILITIES ..............................................................................9 3.1.1 Bismuth Phosphate Process .........................................................................9 3.1.2 REDOX (Reduction Oxidation) Process ...................................................10 3.1.3 PUREX (Plutonium-Uranium Extraction) Process ....................................10 PLUTONIUM CONVERSION .............................................................................11 3.2.1 Plutonium Isolation 231-Z Isolation Building ...........................................11 3.2.2 Plutonium Finishing Plant..........................................................................11 3.2.3 PUREX N-Cell...........................................................................................12 3.2.4 Other Materials Processed at REDOX and PUREX ..................................12 WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES ...............13 3.3.1 Discharges to Ground ................................................................................13 3.3.2 Single-Shell Tanks .....................................................................................13 3.3.3 Double-Shell Tanks ...................................................................................13 HISTORICAL PFP PROCESSING DIAGRAMS ................................................15 OVERVIEW OF PLUTONIUM PROCESSING HISTORY ................................25 231-Z ISOLATION FACILITY PLUTONIUM OPERATION ............................27 PFP PRODUCTION LINES ..................................................................................29 4.4.1 RG Line ......................................................................................................32 4.4.2 Remote Mechanical (RM) A Line .............................................................35 4.4.3 Remote Mechanical (RM) B Line..............................................................36 4.4.4 Remote Mechanical (RM) C Line..............................................................36 SCRAP RECOVERY (RECUPLEX, PRF, MT, 232-Z) .......................................39 4.5.1 RECUPLEX ...............................................................................................39 4.5.2 Plutonium Reclamation Facility (PRF) ......................................................44 4.5.3 Ion-Exchange Recovery of Plutonium .......................................................52 Official Use Only ii

GENERAL HISTORICAL DESCRIPTION OF HANFORD SITE ...................................9

3.2

3.3

4.0

PLUTONIUM FINISHING PLANT (Z PLANT) .............................................................14 4.1 4.2 4.3 4.4

4.5


4.6 4.7

PLUTONIUM FINISHING PLANT LABS ..........................................................54 PFP SUPPORT FACILITIES ................................................................................56 4.7.1 242-Z Waste Treatment Facility ................................................................56 4.7.2 241-Z Sump Tanks .....................................................................................64 4.7.3 241-Z-361 Settling Tank ............................................................................72 4.7.4 Trenches and Crib ......................................................................................75 4.7.5 Conclusion of Plutonium Losses from PFP to Cribs .................................83 SCRAP MATERIAL PROCESSED OUTSIDE OF PFP......................................85 PLUTONIUM PARTICLE SIZE SUMMARY .....................................................85 DIFFICULTIES WITH PLUTONIUM SOLIDS ..................................................90 4.10.1 Solids in 242-Z and PRF ............................................................................90 4.10.2 Use of Filtration and Centrifuges to Limit Loss from PFP Aqueous Waste Stream .............................................................................................93 4.10.3 Conclusions Regarding Centrifuge Operation .........................................107 4.10.4 Plutonium Tetrafluoride Carry-Over and Impact in Tank Farms ............110 OVERVIEW OF PLUTONIUM ACCOUNTABILITY METHODS .................111 PFP WASTE SOLUTION TRANSFERS TO TANK FARMS ..........................117 4.12.1 PFP Aqueous Liquid Discharges after May 1973....................................117 4.12.2 Acid Waste Discharge to 242-T May 1973December 1980 ..................117 4.12.3 Neutralized Waste Discharge to 244-TX December 1981November 2004..........................................................................................................120 4.12.4 Waste Transfer by Truck (216-Z-8, 241-Z-361, TK D9) ........................122 4.12.5 Waste from Solution Stabilization using Magnesium Hydroxide or Oxalic Acid (2003-2004) .........................................................................128 ESTIMATE OF TOTAL PLUTONIUM DISCHARGE TO TANK FARMS FROM PFP...........................................................................................................129 4.13.1 Accountable Losses 1973-2004 ...............................................................129 4.13.2 PRF MUFs and Impact on Waste ............................................................133 CONCLUSION OF PFP LOSSES INCLUDING ESTIMATE OF LARGE PARTICLE FRACTION .....................................................................................138 PROCESSES THAT DID NOT PROCESS PUO2 ..............................................145 5.1.1 Bismuth Phosphate, PUREX, REDOX, Fission Product Recovery, Uranium Recovery ...................................................................................145 5.1.2 Critical Mass Laboratory .........................................................................145 5.1.3 Review of 222-S Laboratory waste collected in the 219-S Waste Handling Facility .....................................................................................151 Official Use Only iii

4.8 4.9 4.10

4.11 4.12

4.13

4.14 5.0

FUEL PROCESSING FACILITIES (T/B PLANT AND REDOX AND PUREX) ........145 5.1


5.1.4 5.1.5 5.2 5.3

231-Z Filtrate Transfers to T-Plant ..........................................................152 Liquid Waste Receipts at the 204-S and 204-AR Facilities ....................154

PROCESSES THAT HAD PUO2 BUT DID NOT DISCHARGE IT TO TANK FARMS ....................................................................................................155 PROCESSES THAT MAY HAVE DISCHARGED PUO2 TO TANK FARMS ................................................................................................................160 5.3.1 REDOX and PUREX Processing of PFP Nitrate Solutions ....................160 5.3.2 Miscellaneous Fuel Campaigns ...............................................................170 CONCLUSION TO NON-PFP PROCESSES .....................................................181 INTRODUCTION TO TANK FARMS CHARACTERIZATION .....................183 CHARACTERIZATION OF WASTE IN TANKS SY-102 AND TX-118 ........184 6.2.1 Tank SY-102 History and Characterization .............................................184 6.2.2 Tank TX-118 History and Characterization Data ....................................188 PLANNED LABORATORY WORK .................................................................189 RECOMMENDATIONS .....................................................................................190

5.4 6.0 6.1 6.2

TANK FARM CHARACTERIZATION AND CHEMISTRY .......................................182

6.3 6.4 7.0 8.0 9.0 10.0

REVIEW PROCESS........................................................................................................191 CONCLUSION ................................................................................................................195 REFERENCES ................................................................................................................199 APPENDICES .................................................................................................................229

TABLE OF APPENDIXES APPENDIX A SCOPE OF THE TWO TEAMS ..................................................................... A-1 APPENDIX B LIST OF ASSUMPTIONS TO VALIDATE AND COMMENT ....................B-1 APPENDIX C 5 REPORTS......................................................................................................C-1 APPENDIX D PLUTONIUM AND ABSORBER CONCENTRATIONS IN FAST AND LOW SETTLING FRACTION ............................................................................. D-1 APPENDIX E INDEPENDENT REVIEW TEAM CHARTER .............................................. E-1 APPENDIX F PLUTONIUM INDEPENDENT REVIEW GROUP REPORT ....................... F-1 APPENDIX G TEAM BIOGRAPHIES .................................................................................. G-1 APPENDIX H REVIEW OF SOLIDS IN PRF EFFLLUENT ............................................... H-1 APPENDIX I TANK TABLES ................................................................................................. I-1 APPENDIX J PU OXIDE-METAL DISCHARGE TO TANK FARM ....................................J-1 Official Use Only iv


LIST OF TABLES

ES-1. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31.

Summary PuO2 and Metal Results ....................................................................................... 2 Single-Shell Tanks at Hanford ........................................................................................... 14 Double-Shell Tanks at Hanford .......................................................................................... 14 Summary of Process Timeframes....................................................................................... 24 Historical Task Numbers and Task Descriptions ............................................................... 30 Overview of PFP Plutonium Processing Activities, 1949 to 2004..................................... 31 Plutonium Scrap Streams to RECUPLEX for Plutonium Recovery (HW-35030) ............ 40 PFP Laboratory Aqueous Waste ........................................................................................ 54 Composition of Hanford CAW Solution ............................................................................ 57 CAW Composition Continuous Waste Treatment Flowsheet ............................................ 58 242-Z Tank Room Assay ................................................................................................... 61 Sources and Volumes of Discharges to 241-Z Facility in 1970 ......................................... 67 Estimated Contaminants in Low-Salt Wastes and Nominal Composition in 1969 ............ 67 241-Z Tank Values Before and After Final Cleaning ........................................................ 69 Inventory Estimates for Sludge Remaining in Tank 241-Z-361 ........................................ 74 RECUPLEX Input to Z-9 Crib ........................................................................................... 82 Summary PSD Data Used in Later Analysis ...................................................................... 90 Examples of Build up of Plutonium Containing Solids in 242-Z ...................................... 92 Examples of the Causes of Presence of Solids in the PRF Solvent Extraction System ..... 92 Flow Sheet Data for Prototype Solids Handling System ................................................... 98 E1W centrifuge Sludge Characterization June 1973 ....................................................... 99 Results on Centrifuged PRF CAW from 1984 and 1987 ................................................. 106 Truck Transfers 241-Z 361 to 241-TX-101 Based on Shift Logbooks Entries................ 125 Total Reported Pu discharged from PFP to Tank Farms Based on Accountability Data (in Kilograms) .......................................................................................................... 131 Splits of Total Pu Discharged as Liquid Waste................................................................ 132 Average CAW Pu Concentration during the 1980s ......................................................... 133 Plutonium Scrap and Waste Loss and MUF Data from PRF ........................................... 134 PRF Plutonium Losses and ID Data from the 1980s........................................................ 136 PRF Operating Hours, Output and Estimated Material Unaccounted for ........................ 137 Total Assumed Pu Discharged from PFP to Tank Farms with Major Process Line Activity ............................................................................................................................. 137 Total Assumed Pu Discharged from PFP Directly to Tank Farms with Percentages Assigned to Pu Waste Types ............................................................................................ 140 Kgs in Waste Stream by Form and Particle Size.............................................................. 142 Official Use Only v


32. 33. 34. 35. 36. 37. 38. 39. 40.

Data Used on Large Particle Determination..................................................................... 143 Pu Recovered at the Processing Plants (MT) ................................................................... 154 Plutonium Transfers from Z Plant to REDOX and PUREX ............................................ 162 Transfers of Z Plant Dissolver Solutions to REDOX and PUREX .................................. 165 Miscellaneous Fuels Dissolved at REDOX and PUREX Plants ...................................... 174 Summary of PuO2 Particle Discharges from REDOX and PUREX Plants ..................... 180 Likely Plutonium Oxide Discharges to the Tank Farms .................................................. 181 Best-Basis Inventory Values for Pu isotopes in Tanks SY-102, TX-105, TX-109, and TX-118....................................................................................................................... 183 Comparison of April 2000 Surface Grab Sample with Underlying PFP Waste and with SY-101 Sludge. ........................................................................................................ 185

LIST OF FIGURES

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Hanford Process Timeline .................................................................................................. 12 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19441949 Timeframe ..... 16 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19491955 Timeframe ..... 17 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19551962 Timeframe ..... 18 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19621964 Timeframe ..... 19 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19641973 Timeframe ..... 20 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19731982 Timeframe ..... 21 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19831989 Timeframe ..... 22 Plutonium Finishing Plant Liquid Waste Discharge Routing: 19902004 Timeframe ....... 23 Historical Flowsheet for 231-Z .......................................................................................... 29 RG Line Flowsheet ............................................................................................................. 33 Early PFP Operation ........................................................................................................... 33 RMC Line Process Pictorial ............................................................................................... 38 RMC Line Flow Diagram Nitrate to Tetrafluoride (PFD-Z-190-00002 B-0) ................. 38 RMC Line Flow Diagram Metal Reduction (PFD-Z-190-00002 B-0) ........................... 39 Simplified Flow Diagram of RECUPLEX Recovery and Coupling Operations (HW-35030) ....................................................................................................................... 41 Simplified RECUPLEX Solvent Extraction Flowsheet (HW-35030) ............................... 43 Scrap Plutonium Recovery Sources for PRF Facility ........................................................ 45 PRF Plutonium Scrap Processing Pictorial ........................................................................ 46 Plutonium Reclamation Flowsheet (PFD-Z-180-00001 Rev. C-1) .................................... 52 Batch Waste Treatment Process ......................................................................................... 63 Official Use Only vi


22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51.

Continuous 242-Z Waste Treatment Flowsheet ................................................................. 64 Schematic drawing of a 241-Z Tank and Tank Array ........................................................ 66 Tank D4 Showing Initial Deposits and Final Deposits ...................................................... 70 May 2005 Inspection of TK D-5 Interior Floor South Side and Agitator ....................... 71 Access Cut through TK-D5 Tank Wall for Interior Cleaning ............................................ 71 Removing Deposit from TK-D8 during Decontamination and Decommissioning ............ 72 361-Z Settling Tank System ............................................................................................... 73 Overview of Z Plant Complex Liquid Waste Disposal Sites ............................................. 77 Description of the 216-Z-9 Trench and Dimensions .......................................................... 80 Plutonium Concentrations on Surface of 216-Z-9 Crib ..................................................... 81 Particle Size Distribution for Hanford Scrap Pu Oxide ..................................................... 87 Particle Size Distribution for RFETS Chloride Scrap Oxide Sent to Hanford .................. 87 Particle Size Distribution for RFETS Pu Oxide from Peroxide Calcination ..................... 88 Particle Size Distribution for Pu Oxide from Magnesium Hydroxide Precipitation and Calcination ................................................................................................................... 88 Particle Size Distribution for Pu Oxide from Burned Metal .............................................. 89 Particle Size Distributions for Hanford Oxalate Source PuO2 ........................................... 89 Wesfalia Centrifuge Sketch ................................................................................................ 94 Photo of Similar Centrifuge ............................................................................................... 94 CAW Centrifuge in 6th Floor............................................................................................. 95 Western States Centrifuges ................................................................................................ 98 Dissolver Pan Filter in MT-5 for Dissolver Solutions ..................................................... 103 Mid 1980s MT Dissolver System ..................................................................................... 105 Leaching test on MT Dissolver Centrifuge Sludge .......................................................... 109 PRF MUF Trend Analysis 19731975 (ARH-CD-411) .................................................. 135 Timeline for Hot Semiworks ............................................................................................ 149 Simplified Liquid Waste Diagram ................................................................................... 160 PFP Filtrate Recycle to REDOX Plant ............................................................................. 169 Filtrate Recycle to PUREX Plant ..................................................................................... 170 REDOX Process Flow Schematic Dissolution of Specialty Fuels ................................ 177 PUREX Process Flow Schematic Dissolution of Specialty Fuels ................................ 178

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ACRONYMS & ABBREVIATIONS

AFAN AL Al(NO3)3 ANN ANN ARHCO ARIES BBI BiPO4 BNW B-PID CCl4 CML CPS CSER CSS CSSG D&D DBBP DBP DL DNFSB DOR DSA DST ER ERDA HF HLSW HN HNO3/HF ID IDMS

ammonium fluoride and ammonium nitrate Analytical Laboratory Aluminum nitrate nonahydrate aluminum nitrate nonahydrate ammonium nitrate Atlantic Richfield Hanford Company Advanced Recovery and Integration Extraction System Best Basis Inventory bismuth-phosphate Battelle Northwest book-physical inventory difference carbon tetrachloride Critical Mass Laboratory criticality prevention specification criticality safety evaluation report Criticality Safety Subcommittee Criticality Safety Support Group decontamination and decommissioning dibutylbutyl phosphonate dibutyl phosphate Development Laboratory Defense Nuclear Facilities Safety Board Daily Operating Reports Documented Safety Analysis double-shell tank electroreduction Energy Research and Development Administration hydrogen fluoride high and low salt waste hydrolyamine nitrate nitric/hydrofluoric inventory difference Integrated Document Management System Official Use Only viii


IDMS La LaF3 LANL LLW MBA MgO MIBK MIS MOX MSMPR MT MT MTU MUF NCSE NDA Np-237 NPH PFP PISA PN PNL PNNL PPSL PRC PRF PRT PRTR PSD PSHS Pu PuF4 PuO2 PUREX

Isotopic dilution mass spectrometry lanthanum lanthanum fluoride Los Alamos National laboratory low-level waste material balance magnesium oxide methyl isobutyl ketone Material Identification and Surveillance mixed oxide mixed suspension / mixed product removal metric tons Miscellaneous Treatment metric tons uranium material unaccounted for nuclear criticality safety evaluation nondestructive assay neptunium-237 normal parrafin hydrocarbon Plutonium Finishing Plant potential inadequacy in the safety analysis partial neutralization Pacific Northwest Laboratory Pacific Northwest National Laboratory Plutonium Process Support Laboratory Plant Review Committee Plutonium Reclamation Facility pre-reduction tank Plutonium Recycle Test Reactor particle size distribution Prototype Solids Handling System plutonium Plutonium Tetrafluoride plutonium oxide Plutonium Uranium Extraction

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RB REDOX RFETS RG RGL RLW RMA RMB RMC S&C SC SEM SEV SRS SS&C SST SX TBP TRU TRUEX TWINS U U-233 VRT WRPS WTP XRD

Reception and Blending Reduction-Oxidation Rocky Flats Environmental Technology Site Rubber Glove Rubber Glove Line radioactive liquid waste Remote Mechanical A Remote Mechanical B Remote Mechanical C sand and crucible Slag and Crucible Scanning Electron Microscopy spherical equivalent volume Savannah River Site sand, slag, and crucible single-shell tank solvent extraction system tributyl phosphate transuranic transuranic extraction Tank Waste Information Network System uranium uranium-233 vacuum receiver tank Washington River Protection Solutions Waste Treatment and Immobilization Plant X-ray Diffraction

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1.0

EXECUTIVE SUMMARY

Based upon the results of the M-3 mixing studies for the Waste Treatment and Immobilization Plant (WTP) pretreatment facility, a concern emerged over the settling of greater than 10 micron plutonium-bearing particles in WTP process vessels. Specifically, members of the WTP technical staff believed that the Plutonium Finishing Plant (PFP) may have transferred large, dense plutonium oxide particles to the tank farms which could then be sent to WTP for processing. Therefore, WTP management commissioned a three-person team (WTP team) of former Hanford employees with extensive PFP and tank waste experience to investigate if large, dense plutonium-bearing particles could be present in the tank farms. In February 2011, the draft report prepared by this team was given to Washington River Protection Solutions (WRPS) management for their review. The draft report indicated that there was a possibility that large, dense plutonium-bearing particles could be present in the waste tanks. WRPS concluded that the presence of such particles could exceed the analyses of the criticality safety evaluation report (CSER) for the waste tanks. In response to these findings, and because the original team did not have broad access to process documentation and no access to classified documentation, WRPS management commissioned a second team (WRPS team) to investigate the issue and determine the extent of the problem using all available sources of information. The scope of the WRPS teams review was to: Determine all source facilities that contributed plutonium oxide (PuO2) or plutonium oxalate to the tank farm Determine all the tanks that received PuO2 or oxalate Determine how much plutonium (Pu) was sent to each tank and identify its chemical and physical form Determine the particle size and density of the plutonium disposed to the tank farms, specifically looking for particles greater than 10 microns.

As part of the review, questions about the disposal of plutonium fluoride compounds (e.g., PuF4) to the Hanford waste tanks were investigated. Accordingly, the WRPS team reviewed the chemistry of Pu oxalate and Pu fluoride compounds to determine if large dense particles would persist in the alkaline tank waste environment. The investigation determined that oxalate and other crystalline forms, when not calcined and after neutralization, were converted to light, fine particles of low-solubility plutonium hydrous oxide, PuO2x H2O, and would not be an issue. In addition, the precipitated plutonium would be bonded to other particles or poisons, making a co-precipitated agglomerate. In this manner, they would be no different than the other plutonium hydrous oxide discarded as reprocessing operations losses in the tank farm. Plutonium fluoride compounds likewise were found to form finely divided low-solubility plutonium hydrous oxide. When reviewing all the processes that sent Pu to the tank farms, three facilities; PFP, Plutonium Uranium Extraction (PUREX) plant, and Reduction-Oxidation (REDOX) were found that sent Official Use Only 1


large dense particulate plutonium-bearing material. The materials were primarily in the form of calcined plutonium dioxide, PuO2. This team estimated that approximately 100kg of Pu was sent to the tank farms from plutonium oxide processing in different facilities. Of this quantity, approximately 30 kg was disposed as large (>10 micron) and dense calcined PuO2 and plutonium metal fines, with the balance discarded in the form of plutonium nitrate, plutonium hydroxide, or plutonium oxalate and compounds that would readily decompose in alkaline waste solution to form fine plutonium hydrous oxide. The PFP facility contributed a majority of the calcined PuO2 with approximately 23 kg plutonium sent that was greater than 10 microns. Of that 23 kg, the WRPS team estimates that PFP discarded as much as 2.5 kg of plutonium as fine metal particles from incomplete metal burning subsequent to oxide dissolution. The PUREX and REDOX facilities sent approximately 7 kgs of similar calcined plutonium oxide material. Eight tanks received an appreciable quantity (>750 g) of oxide or metal from the three facilities. They are TX-105, -109 and -118, 244-TX, SY-102, C-102, AN-101, and S-108. In addition there were eight more tanks that received minimal amounts (10-micron particulate Pu oxide and Pu metal. This inventory is located in 16 tanks; eight with minimal quantities, and eight with appreciable quantities that could challenge the CSER. Particle sizes range from 10100 microns and densities range from 811 g/cc with approximately 2.5 kg present as 19 g/cc metal.

2.0 2.1

BACKGROUND INFORMATION PROBLEM STATEMENT

The current CSER assumes that Pu in tank waste is in finely divided forms intermixed with neutron absorbers. A recent report issued by the WTP has identified the possibility that large PuO2 particles could be in the waste, having originated from PFP. The PuO2, being large and dense, could potentially segregate from the lighter or smaller neutron absorbers during mixing operations, thus invalidating the assumptions in the CSER. This phenomenon could also cause issues with the use of pulse jet mixers at WTP. There are concerns that the pulse jet mixers may not effectively mix the dense PuO2 particles above 10 microns effective spherical diameter.

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The purpose of this investigation is to determine the presence of PuO2 in the waste tanks. If the PuO2 exists, estimate the quantity, determine the particle size and density, and determine the current location of the PuO2 in the tank farm. The scope of this study includes both PFP and other processing facilities that could be sources of PuO2. Additionally, the potential for the creation of PuO2 in the tank farm itself (by particle growth, or decomposition of plutonium oxalate or fluoride) will also be investigated.

2.2

PREVIOUS WORK 2010 WTP REPORT

An investigation was initiated in December of 2009 by WTP Criticality Safety to review historical information on plutonium solids that were entrained in PFP aqueous waste and were subsequently transferred to the tank farms. The purpose of this study was to have Hanford Site subject matter experts review available data and records concerning discards of plutonium liquid wastes from the PFP, particularly as related to the concerns surfaced by the DNFSB about plutonium quantities, plutonium particle sizes, and plutonium particle density. The study was completed the following year and a draft report, Historical Overview of Solids in PFP Aqueous Waste Transferred to Tank Farms: Quantity of Plutonium, Particle Size Distribution, and Particle Density, was issued in June 2010 (24590-CM-HC4-W000-00176-T02-01-00002 Rev 00B) and revised in 2011 (24590-CM-HC4-W000-00176-T02-01-00001). The key findings of this review of available historical information are summarized below: Over its lifetime, PFP realized a persistent problem with plutonium solids being entrained in liquid solutions, pipelines, tanks, and waste discards. The source for most of the plutonium solids entrained in the plutonium solutions and waste streams were from the recovery and recycle of out-of-specification plutonium materials. Pu solids from scrap recovery may be significantly different from product oxide. Plutonium oxide particulates entrained in PFP waste solutions were discarded to cribs and trenches and varied in size up to 100 m in diameter. Plutonium accountability methods on liquid waste discards were biased low, presumably because the methods frequently did not adequately account for the plutonium solids that were entrained in the liquid waste. WPRS estimates that the amount of plutonium transferred from PFP to tank farms may be underestimated by a factor of approximately 2. Efforts to minimize plutonium solids in PFP solutions were implemented over time, utilizing various combinations of filters and centrifuges. These strategies helped to reduce the solids entrainment, but they did not resolve material unaccounted for (MUF) issues nor eliminate significant plutonium solids accumulation in various tanks. Actual data, on the plutonium solids entrained in plutonium waste solutions transferred to tank farms, is unavailable because these wastes were uncharacterized for plutonium solids. Official Use Only 4


Particle densities for plutonium oxides prepared by various methods have been reported to range from approximately 311 gm/cc. A most likely estimate of 65 kgs of plutonium was sent from PFP to the tank farms. The WTP team believes that the lowest estimate would be 30 kgs and a worst case estimate of 130 kgs. Values outside this range would be difficult to support.

The findings of the preliminary investigation indicated that plutonium processing activities in PFP generated plutonium materials during both production and scrap recovery operations whose particle size distributions included a significant fraction that was greater than 10 microns in diameter (spherical equivalent volume [SEV]). Strategies were implemented to minimize entrainment of these solid materials in the waste streams utilizing filters and centrifuges during the timeframe that waste was transferred to tank farms. Data was identified to indicate that significant amounts of these solids still remained in the waste solutions. Therefore, it is highly probable that plutonium solids with particle sizes greater than 10 microns were entrained in the waste solutions transferred to tank farms.

2.3

IMPACT OF 2010 WTP REPORT PISA ISSUED

After the WTP report was issued, WRPS evaluated its impact on the Hanford tank farms. Even though the report was a draft, WRPS management, in consultation with DOE, decided to consider the report as new information. On February 14, 2011, the Plant Review Committee (PRC) convened to review the results of the preliminary evaluation and determined that the new information in the WTP document on plutonium particles in tank farms tanks from PFP aqueous waste constitutes a Potential Inadequacy in the Safety Analysis (PISA) to the Documented Safety Analysis (DSA). As a result, the PISA was categorized as a Group 3B, Documented Safety Analysis Inadequacies, (2) SC-3 event. This review led to issuance of occurrence report EM-RP-CORPS-TANK FARM-2011-0004, Aqueous Waste Particle Size Transferred from Plutonium Finishing Plant May be Larger than Previously Evaluated. WRPS determined that a PISA exists for the Tank Farm Documented Safety Analysis because a recent WTP document casts doubt that the PuO2 particles in the aqueous waste transferred from PFP to the Tank Farms are of a size less than 10 microns equivalent spherical particles. If the PuO2 particles are large, dense particles, then they potentially could preferentially settle and concentrate in a diluted liquid environment such as exists during retrieval operations. The information in the WTP document is related to whether presence of large PuO particles might result in differential settling that would result in exceeding the 2.6 grams/l limit identified in CPS-T-149-00012, Criticality Prevention Specification. Under current management direction, the WTP report is to be treated as identifying a potential to exceed the criticality prevention specifications. A Red Arrow entry was made in the Central Shift Managers logbook. This red arrow restriction prohibits mixer pump operations and retrieval of sludge from SY-102, TX-101, TX-118 and 244-TX until a peer review and associated technical evaluation of the results of a

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recently issued WTP report, Potential Criticality in Hanford Tanks Resulting from Retrieval of Tank Waste, are completed. After the PRC review and the issuing of the occurrence report, the Criticality Safety Subcommittee (CSS) convened to review the issue. They spent approximately three weeks reviewing documents and interviewing people to determine how the issue should be investigated. Draft memo CCN:228133, Plan/Schedule for WTP/Tank Farms Issue Identification/Resolution, was issued and WRPS began to assemble a team to investigate the issue based upon the CSS recommendations. In mid-March members were identified and a plan of action was developed (external letter WRPS-1101477, Contract Number DE-AC27-08RV14800 Washington River Protection Solutions LLC Plutonium Oxide Resolution Plan) to resolve the issue.

2.4

PLUTONIUM OXIDE RESOLUTION PLANS

Guidance for Follow-On Investigation The authors of the WTP 2010 study indicated they did not have sufficient time, support, resources, nor access to historical Hanford documents that were publicly unavailable. They knew from previous work in PFP that some of those unavailable documents might provide significant additional information and further clarification in many areas. Based upon this information, the authors of the 2010 WTP report were asked to develop a list of assumptions and open issues that, if confirmed or nullified, would either validate, clarify, or possibly better define their findings. This listing is provided in Appendix B, List of Assumptions to Validate and Comment. The items on this list are categorized into: Statements of Fact, Assumptions, and Areas Needing Further Investigation. The WRPS team used this listing to help focus the follow-on investigation and ensure the investigation was thorough and complete. Criticality Safety Support Group/Washington River Protection Solutions Teams Since 2008, the Criticality Safety Support Group (CSSG) has been reviewing the development of the WTP nuclear criticality safety evaluation (NCSE) because WTP is a new facility design. In mid 2009, the DNFSB began questioning the possibility of Pu solids accumulation based upon the WTP mixing studies. In December 2009, the CSSG began reviewing the tank farm criticality status due to impending preparations for waste mobilization. In addition, the CSSG was requested to review the WTP mixing study for criticality implications. Based upon these reviews, in January 2010, WTP commissioned a study to determine the source and amount of Pu solids that could be present in tank waste. The draft report was given to WRPS in early February 2011. An independent review team made up of members of the CSSG was asked to evaluate the report and determine the impact. That review resulted in a draft

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plan/schedule being developed in late February (draft memo CCN:228133 [Appendix A, pages 47]) After the draft plan was issued, WRPS commissioned a team to conduct the investigation outlined by the independent review team. A team was assembled including the original authors of the WTP report, Pacific Northwest National Laboratory (PNNL), WTP, WRPS, and contract personnel Team members as follows: Walt Isom Ted Venetz Jacob Reynolds Cal Delegard Susan Jones David Place David Lini Robert Watrous David Bowers Richard Hoyt Tom Jones Joseph Teal Team Lead SRS Plutonium and Tank Farm processing PFP Team lead and PFP process engineer Purex/Redox Team lead and Tank Farm Waste Characterization Staff Scientist, PFP Lab and PNNL Chemist and Development Lab PFP and PNNL Purex and Tank Farm process engineer Consultant PFP processing and chemistry Consultant Purex and Redox process engineer Consultant Tank Farm and Evaporator process engineer Consultant Pu Precipitation expert and PFP processing Consultant Tank Farm and PFP liquid discharge Consultant Tank Farm and PFP processing

From the original draft plan, a separate resolution plan was developed to determine the extent of the problem (external letter WRPS-1101477 [Appendix A, pages 13]). The plan defined the scope of the review to answer four main questions: Determine all the source facilities that contributed PuO2 or Pu oxalate to the tank farms Determine all the tanks that received the PuO2 or oxalate How much was sent to each tank and its form Determine particle size and density of the Pu.

In addition, the plan would have the WRPS team investigate the disposal of plutonium fluoride compounds (e.g., PuF4) to the Hanford waste tanks. As such, the team would review the chemistry of Pu oxalate and Pu fluoride compounds to determine if they formed large dense particles when made alkaline before being sent to the tank farms. The plan set up two WRPS teams to investigate the issues. The first WRPS team (PFP) was to review the PFP facility to determine what was sent to other facilities for processing and to the tank farms as waste. The team would use members familiar with PFP operations with access to confidential documents to answer the four questions and to close open items in the 2010 report. The second WRPS team (PUREX/REDOX) was to review all other site facilities that may have received PFP material for processing or sent PuO2 or Pu oxalates to the tank farm. The investigation started by reviewing the PUREX, REDOX, Hot Semi Works, and the Critical Mass Laboratory (CML) facilities. The goal for this team was to confirm the transfers from the PFP

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facility to the other facilities, in addition to reviewing other processing campaigns undertaken by those facilities that could have sent PuO2 and Pu Oxalate to the tank farm. The second WRPS team used PNNL personnel to assist investigating the fate of Pu oxalate and Pu fluoride compounds in the alkaline tank waste discussed above. The SY-102 tank sample crystalline structure was the starting point to determine what it is, how they may have been formed, and its impact to this study. The teams were not assigned to investigate the Pu nitrate solutions that, when neutralized, hydrolyze to form light, fine particles. The teams were directed to use all sources of information available such as, but not limited to, classified documents, logbooks, weekly and monthly reports, reports in the Integrated Document Management System (IDMS), and interviewing current and past workers to establish how the facilities operated. The final product for this effort is a technical report that answers the questions above. This report is an overarching document that builds on the existing WTP work completed in 2010. The plan is not to revise the existing document, but to review and identify open issues/assumptions by understanding how the document was prepared. With access to documents and other resources, including classified documents unavailable to the WTP team, the WRPS team could resolve or close many of the open issues based upon new-found information. With the new information, the original WTP authors will decide if revision is needed to the WTP original document. If, after this review, documentation is unavailable to close an open issue, the WRPS team will develop a best-basis estimate with a defensible technical justification to close any remaining open issues. This report is constructed based on a chronological process history. Like the investigation, it began with the start of facility processing and continues until the facilities were shut down. The history of how the facility was operated is essential to understanding how material could have been released to the tank farms. The PFP section gives a description of the process and then reviews how the process was modified over time and how those changes affected the waste discharges. It discusses the interaction between the PFP facility and the other processing facilities and how the wastes were discharged to the tank farm. The Fuel Processing and Tank Characterization section follows the same format, reviewing all the facilities at Hanford and their capability to send Pu dioxide to the tank farm. This section contains the review of the chemistry of Pu oxalate and Pu fluoride compounds to determine if they made large dense particles when made alkaline before and after being sent to the tank farms. The purpose of the WRPS team was only to document the specifics concerning Pu oxide and its various forms that exist in the tank farms. Future studies will determine the impact and necessary corrective actions regarding WRPS waste retrieval and WTP mixing efforts.

Official Use Only 8


3.0

GENERAL HISTORICAL DESCRIPTION OF HANFORD SITE

The Hanford Site in Washington State was a primary source of United States plutonium production. Between 1944 and 1989, Hanford produced 60 percent of the Pu. The Hanford Site received uranium (U) billets from other DOE facilities for fuel fabrication, irradiated the fuel in eight production reactors and one co-generation reactor, and reprocessed the fuel to extract Pu and U. The Pu was converted into metal and either shipped to other sites or manufactured into weapons components. The U was shipped offsite for recycling into metal. The waste from reprocessing and manufacturing was discharged to ground and underground storage tanks. Fuel fabrication was carried out in Hanfords 300 Area from 1943 to 1986. The nuclear fuel fabricated at the Hanford Site was solid natural (later low enriched) U metal fuel elements, clad in aluminum-silicon (later Zircaloy-2)a. Fuel was then irradiated in nine reactors clustered along a 13mile stretch of the Hanford shoreline of the Columbia River, known as the 100 Areas. Reactor operations themselves did not generate tank wastes. Decontamination wastes and ion exchange resin wastes from the reactor operations were discharged to the waste tanks.

3.1

REPROCESSING FACILITIES

Reprocessing nuclear fuel evolved with time at the Hanford Site. The initial process was a co-precipitation process which was followed by two solvent extraction processes. All of these processes were enhanced to improve recovery of product and to increase throughput. 3.1.1 Bismuth Phosphate Process

Irradiated fuel elements were transported to the Sites 200 Areas for reprocessing. The earliest radiochemical processing operations at Hanford began at the 221-T Building, also known as T Plant, in December 1944. The T Plant was supported by the 224T Concentration Building, the 222T Process Control Laboratory and other associated support structures. The next reprocessing facility built at Hanford was known as the B Plant, which began processing irradiated U in April 1945. The T and B Plants used the bismuth-phosphate (BiPO4) process, a batch, co-precipitation process. The bismuth phosphate process recovered plutonium from irradiated fuel through a series of co-precipitation processes. The initial operations in the canyon building recovered plutonium from the fission products and uranium by the co-precipitation of plutonium phosphate and bismuth phosphate. After two additional precipitation steps to decontaminate the Pu, the product from the bismuth phosphate 221 Building was purified and concentrated in 224-T or 224-B. In the Concentration Building (224 Building), the product was purified, product volume

Zircaloy-2 is an alloy composed chiefly of zirconium, blended with small amounts of tin, iron, chromium and nickel. It is not a trademarked product name.

a

Official Use Only 9


was reduced, and the carrier was switched to lanthanum fluoride. The final purification was completed in the 231-Z facility where a plutonium nitrate paste was produced. The BiPO4 process was a batch operation that did not recover uranium, generated large waste volumes, and did not have a production rate that was considered adequate; which led to the development of two solvent extraction processes for reprocessing the fuel. The REDOX process, a continuous solvent extraction process, was developed first (Section 3.1.2). The B Plant was shut down in 1952, as soon as the REDOX Plant became operational. The T Plant was shut down when the PUREX plant started up in 1956 (Section 3.1.3). 3.1.2 REDOX (Reduction Oxidation) Process

The REDOX process was housed in the 202-S Building and began operating in January 1952. The REDOX process recovered both Pu and U using continuous, countercurrent solvent extraction process. The aluminum cladding on the irradiated fuel slugs was removed by a dissolution process. Then the exposed uranium fuel was dissolved in boiling nitric acid. The resulting solution was processed through a series of packed solvent extraction columns. The organic phase used was methyl isobutyl ketone (MIBK), commonly known as hexone. Through a series of oxidation-reduction operations the Pu and U were separated from each other and also from the fission products. The uranium and plutonium nitrate streams were further purified and the final plutonium product stream was transferred to the 231-Z facility for further purification. Once the REDOX plutonium product met the feed specifications for the 234-5 Building, the plutonium product from REDOX was transferred directly to the 234-5Z Building. REDOX was designed to process an average of 1 to 2.5 metric tons (MT) of natural irradiated U per day. A series of upgrades increased the production rate to 11 to 12 metric tons uranium (MTU) per day by 1958. Part of the Phase II Capacity Increase project constructed the 233-S Plutonium Concentration Building. The REDOX plant began processing slightly enriched irradiated uranium fuel assemblies, known as E-metal in 1958. During 1961-62, new anion exchange Pu concentration equipment was installed in the 233-S Building. REDOX ceased operations in 1967. 3.1.3 PUREX (Plutonium-Uranium Extraction) Process

The PUREX process was developed due to the need for even greater production capacity. PUREX extraction process was similar to REDOX process, but used tributyl phosphate (TBP) in normal parrafin hydrocarbon (NPH) as extractant and solvent, respectively. The PUREX plant was designed to process 200 MT of irradiated, aluminum-clad U per month. The plant (also known as 202-A Plant) soon surpassed its design capacity. By October 1957, PUREX demonstrated a sustained production rate of 20 MTU per day. By 1958, PUREX was processing 79% of Hanfords total Pu output. A series of reliability improvements at the PUREX plant during 1959-61 brought enlarged and reconfigured equipment. In late 1965, PUREX systems were again modified to allow the plant to sustain normal operations at four times capacity factor, or 33 MTU/day. Official Use Only 10


Beginning in 1963, the PUREX plant was modified to allow it to process various fuel types, including fuel from N Reactor. N Reactor fuel elements were zirconium clad solid uranium fuel tube-in-tube arrangement. The outer tube contained 0.95 enriched uranium and some of the inner tubes were enriched to 1.25 percent 235U. In 1966, annular dissolvers and a special Zirflex process were emplaced in PUREX to accommodate N Reactor fuel. The process dissolved the fuel coating (Zircaloy-2) with a mixture of ammonium fluoride and ammonium nitrate (AFAN). The uranium metal was then dissolved in nitric acid. Once PUREX began separating N Reactor fuel, the PUREX processing rate fell to about 2,000 MTU/year for N Reactor fuel, from 5,000 to 7,000 for aluminum clad fuel. In 1972, the PUREX plant began a shutdown that lasted for 11 years. In 1983, the PUREX plant started reprocessing N Reactor fuel for approximately five years. It closed for about six weeks in early 1988, and again for a year beginning in December 1988. After a short stabilization run during late 1989March 1990, the plant again closed, and was placed on standby status in October 1990. The government issued a final closure order in December, 1992, bringing the end of plutonium production and processing at the Hanford Site.

3.2

PLUTONIUM CONVERSION

Hanford developed a number of processes to convert Pu nitrate to either metal or oxides. These processes allowed for either further processing of the Pu or aided in the conversion to product forms such as metal, oxide or fabricated weapons components. 3.2.1 Plutonium Isolation 231-Z Isolation Building

The Pu nitrate product from the 224-B and T Buildings containing excessive impurities, was sent to the 231-Z Building in the 200 West Area. In 231-Z, the Pu-bearing solution was purified by a two-cycle precipitation process with hydrogen peroxide, sulfates, ammonium nitrate, and sulfuric acid. Initially the final product was concentrated Pu nitrate paste that was shipped to the Los Alamos Site. The plutonium product sent to the 234-5 Building was initially concentrated plutonium nitrate, then plutonium peroxide or plutonium oxalate. 3.2.2 Plutonium Finishing Plant

When the 234-5Z facility came online in 1949, it became the major receiver of the plutonium product from 231-Z, REDOX and PUREX. The construction of the 234-5Z facility represented a major expansion of Hanfords role in nuclear weapons production. This facility was designed to convert plutonium nitrate into metal and then into weapons components. Many Hanford documents refer to the collection of Z facilities supporting plutonium finishing activities as Z Plant. As plutonium processing capabilities expanded in areas of scrap recovery and waste treatment over the years, the expanded plutonium processing operation was referred to as the Plutonium Finishing Plant.

Official Use Only 11


3.2.3

PUREX N-Cell

During the PUREX shutdown period starting in the 1970s, the M-Cell and N-Cell within the PUREX plant were modified to convert Pu nitrate to Pu oxide. Preparation tanks were added to a partitioned section of M-Cell, and a precipitation, calcination, blending and oxide product can loadout process was installed in N-Cell. Additional changes were made to the loadout configuration of Q Cell. 3.2.4 Other Materials Processed at REDOX and PUREX

The PUREX and REDOX plants also processed small quantities of other irradiated materials. In 1962, J and Q Cells in PUREX were modified to separate neptunium-237 (Np-237). During 1965 and 1966, PUREX processed 664 tons of powdered thorium oxide fuel targets that had been irradiated to produce uranium-233 (U-233). Another campaign in 1970 processed 820 kilograms (kgs) of pelletized thorium oxide targets. At REDOX, mixed oxide (MOX) fuel from the Plutonium Recycle Test Reactor (PRTR), as well as pelletized U fuels from the Shippingport (Pennsylvania) commercial reactor were processed during 1963-1967. PUREX also reprocessed some PRTR fuel in 19691972. Figure 1. Hanford Process Timeline



3.3

WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES

Waste from the various reprocessing and Pu processes was categorized by the amount of the radioactivity associated with the stream. Waste streams containing the least amount of radioactivity were discharged to surface ponds and trenches. Waste streams containing moderate levels of activity were discharged to sub-surface cribs and trenches. Waste streams with the highest level radioactivity were discharged to underground tanks. 3.3.1 Discharges to Ground

The largest of the waste discharged to the ground from the process facilities (including PFP) consisted of cooling water and steam condensates that were, by design, not contaminated with radioactivity. These cooling water streams were discharged to surface ponds for evaporation and infiltration. However, over time all of the large 200-Area ponds became contaminated from various process upsets, equipment failures and errors in waste transfer operations. More contaminated waste streams from process operations were discharged to cribs and trenches (WHC-MR-0227, Tank Wastes Discharged Directly to the Soil at the Hanford Site). Before 1973, all PFP wastes had been ground-disposed. In 1973, PFP waste (excluding cooling water) began to be routed to the 241-TX tank farm. With the withdrawal of the SSTs from service, the PFP waste was later discharged to 241-SY-102. During the 1970s, additional wastes were routed to Hanford tanks, including some 300 Area laboratory wastes, decontamination wastes from N Reactor, and ion exchange resin wastes from the N fuel storage basin. As work progressed at Hanford, fewer and fewer streams were designated for ground disposal without treatment. This practice was terminated in the mid 1980s with the construction of effluent treatment facilities. 3.3.2 Single-Shell Tanks

The installation and operation of single-shell tank (SST) farms included the design and construction of individual farms, the associated chemical processing operations that generated tank waste, evolutionary features of SST farms, and various secondary waste handling operations. Table 1 provides a list of the SST farms, their capacities, and time periods of initial periods of operation. The chemical processing work isolated long-life fission products, minimized waste volumes, and eliminated free liquids. Streams with lesser radionuclide content were discharged from the tanks system to the soil column. 3.3.3 Double-Shell Tanks

After 241-AX farm, construction and use of double-shell tanks (DSTs) began. Hanfords DSTs were all constructed of carbon steel, with stronger grades of steel being used over time. Each DST had an annulus between its two walls, and was then surrounded by reinforced concrete. Some tanks were equipped to accommodate self-boiling wastes and all had leak detection capability. The majority of the waste in the DST system came from stabilization operations from the SST system. The tanks in 241-AZ tank farm also received waste from PUREX clean out operations. Official Use Only 13


Table 1. Single-Shell Tanks at Hanford200 East Area B&C Tank Farms: Built 1943-44 twelve 530,000-gal tanks (each) Plus four 50,000-gal tanks (each) BX Tank Farm: Built 1946-47 twelve 530,000-gal tanks BY Tank Farm: Built 1948-49 twelve 758,000-gal tanks A Tank Farm: Built 1953-56 six 1-million-gal (Mgal) tanks AX Tank Farm: Built 1963-65 four 1-Mgal tanks 200 West Area T&U Tank Farms: Built 1943-45 twelve 530,000-gal tanks (each) Plus four 50,000-gal tanks (each) TX Tank Farm: Built 1947-48 eighteen 758,000-gal tanks TY Tank Farm: Built 1951-52 six 758,000-gal tanks S Tank Farm: Built 1950-51 twelve 758,000-gal tanks SX Tank Farm: Built 1953-55 fifteen 1-Mgal tanks

Table 2. Double-Shell Tanks at Hanford200 East Area AY Tank Farm: Built 1968-70 two 1M-gal tanks AZ Tank Farm: Built 1970-74 two 1M-gal tanks AW Tank Farm: Built 1976-80 six 1.16M-gal tanks AN Tank Farm: Built 1977-80 seven 1.16M-gal tanks AP Tank Farm: Built 1982-86 eight 1.16-Mgal tanks 200 West Area SY Tank Farm: Built 1974-76 three 1M-gal tanks

4.0

PLUTONIUM FINISHING PLANT (Z PLANT)

This section examines the operation of the Hanford plutonium facilities over their history of operation. It is broken down into a review of the processing lines, process changes, support facilities, solids issues, and an estimate of how much plutonium may have been released to the tank farm. Process flow diagrams, with emphasis on the waste routings and how they changed over time are presented for all operating timeframes. A discussion of historical production is provided along with descriptive detail about the conversion processes (nitrate to metal or oxide) and the scrap recovery processes; which will assist in understanding how plutonium oxide was released to the tank farms. Additionally, a discussion of laboratories and other support facilities



is also provided, including waste treatment facilities, tanks, and cribs that received or collected PFP waste solutions. Particle size data on plutonium in waste solutions is very limited, primarily related to soil studies on crib sites that received waste. Therefore, particle size data on PFP product and scrap oxides is presented to show the range of values expected. The difficulties experienced with solids accumulations in PFP and the waste streams, which was a life-long problem at PFP, is discussed along with methods taken to control and prevent accumulations and conclusions in regard to their effectiveness. A discussion of accountability methods used on waste streams is presented with emphasis on the problems of unmeasured particulate. The presentation of the historical data and historical problems with solids accumulation and discharge is used to focus on the magnitude of the problem that was expected to continue after May 1973 when PFP waste solutions were routed to Tank Farms. The changes in waste solution receipt and treatment are presented along with an estimate of total plutonium discharge to tank farms from PFP. The plutonium estimate includes a value for unmeasured particulate, based on a review of material un-accounted for analysis, after centrifuges were employed on the PRF waste stream. Finally the fate of each form of particulate plutonium discharges is explored and an estimate of the amount of large particulate plutonium, greater than 10 microns, is presented along with conclusions in regard to the discharge of plutonium to tank farms from the PFP.

4.1

HISTORICAL PFP PROCESSING DIAGRAMS

Figures 2 through 9 depict the flow of plutonium-containing liquid waste discharges from PFP and 231-Z over their operating lifetimes and how the processes and waste routings changed over time. The individual figures depict the individual plant operations that generated the liquid waste and the routes of the liquid wastes through the plant to the 241-Z Sump tanks to the disposal site. The diagrams were used to trace the past operations and investigate the way materials were handled, how PFP operated and how waste streams flowed during various periods of operation. A summary of the process changes shown on these diagrams is detailed in Table 3.



Figure 2. Plutonium Finishing Plant Liquid Waste Discharge Routing: 19441949 Timeframe
























Table 3. Summary of Process TimeframesTime frame 19441949 Description 231-Z operations only, filtrate from peroxide precipitation recycled to 224-T 231-Z (peroxide precipitation) 234-5 oxalate precipitation, calcination and hydro-fluorination in Rubber Gloveline and RMA (1952). Filtrates recycled to 224-T and REDOX. RECUPLEX (March 1955) 233-S (April 1955) PUREX (Jan 1956) RMA Continuous Task I-II (1957) RMC Line (1960) Limited in-house scrap recovery. RECUPLEX down Filtrate recycled to REDOX/PUREX Oxide/skulls dissolved and sent to PUREX/REDOX Filtrate sent to Ion Exchange (Oct 1962) RMC in metal production RMA in oxide production Plutonium Reclamation Facility -236-Z (1964) Waste Treatment Facility 242-Z (1965) Concerns Solids in filtrate carry though process. 224-T discharges to 200 series T farm tanks Solids in filtrate carry though process. Oxide and PuF4 entrained in furnace off-gas, (Tech manual indicates 0.02 gm per 320 gm charge). Mitigation Filtrate treated with permanganate and heating Noted Off Normals

19491955

Filtrate treated with permanganate and heating.

19551962

Oxide particulate in RECUPLEX CAW (unmeasured). Solids in filtrate carry though process. Oxide and PuF4 entrained in furnace offgas. Oxide particulate in dissolver solutions sent to separations facilities. Solids carry over in filtrate. Oxide and PuF4 entrained in furnace offgas.

100 micron filters on RECUPLEX waste discharge. Sintered SS Blowback filters on calciner off-gas, carbon filters on FLUR off-gas stream Permanganate added to filtrate. Cake wash discontinued to save volume.

Greater than 3 times the accountability value was discharged to Z-9. Oxide particle found in later soils characterization work

19621964

Solids noted in filtrate and some dissolver solutions, sent back to PFP for filtration.

19641973

Oxide particulate in dissolver solutions. Solids carry over in filtrate. Oxide and PuF4 entrained in furnace off-gas.

CAW crud filter (1967) CAW centrifuge (1967) Prototype Solids Handling System Project (1973) Analytical methods found to significantly under report Pu in liquid waste (1967) Centrifuge Operation improved and specification for use improved. TK-D5 monitored for buildup using NDA

Pu buildup in 242-Z tanks led to continuous process. MUFs out of control for extended periods, blamed on solids, new centrifuges recommended. Blowback filters found corroded. One left out and oxide proliferated through PRF. Anecdotal evidence of 241-Z to 242-T transfer line noted as full of solids. Evidence of continued unmeasured losses from PRF after centrifuges was put in operation.

19731982

Waste Discharged as acid to Tank Farms -242-T RMC Shutdown, only RMA operated as oxide line. 242-Z/PRF shutdown in 1976. Cleanout PRF/RMA stabilization run in 1978 1979

Oxide particulate in dissolver solutions. Solids carry over in filtrate. Oxide entrained in furnace off-gas. Transfers of sludge from Z-8 and SN from 241-Z-361 to tank farms



Table 3. Summary of Process TimeframesTime frame 19821989 Description RMC and PRF restarted. Waste neutralized in 241-Z TK-D5 and discharged to 244-TX Concerns Oxide particulate in dissolver solutions. Solids carry over in filtrate. Oxide and PuF4 entrained in furnace off-gas. Mitigation Centrifuge operation required for operation. Ferric nitrate additions made to waste to dilute Pu solids content. Noted Off Normals Solids still causing high waste loss in PRF. RMC carbon filters checked weekly for powder plugging. Filtrate Evaporator failure results in 2500 gm loss to Tk-D4 1100 grams noted in TK-D7

19902004

Major Process lines shutdown, PRF training run aborted, many tanks flushed, Solution stabilization via MgO and oxalate precipitation.

Filtrate from precipitation discharged to tank farms without treatment. Discharge limit raised to 10X historical value (1200 gms/batch)

Absorbers credited in TK D5

4.2

OVERVIEW OF PLUTONIUM PROCESSING HISTORY

The Hanford Site was selected for the construction and operation of nuclear reactors and separation plants during the early 1940s for the production of plutonium as part of the Manhattan Project during World War II. Plutonium production, finishing, and various metal component manufacturing at Hanford were dynamic processes that continually evolved to meet the ever-changing requirements for special nuclear materials to support various defense and non-defense needs. The 231-Z Plutonium Isolation Facility, the first Z building, became operational in 1944/1945 and provided the final purification and isolation steps for plutonium from the bismuth phosphate process operating at the B and T Plants from 1944 through 1956. After 1956, this facility became the focal point for plutonium metallurgy research and development activities. The initial operation in 231-Z Isolation Facility was the conversion of plutonium incorporated within a lanthanum fluoride carrier into plutonium nitrate paste or glass for shipment offsite. A detailed description of the 231-Z separations chemistry can be found in the Hanford Technical Manual (HW-10475) and a short synopsis of 231-Z plutonium activities is provided in section 4.3 During the mid 1940s, the Hanford operating contractor was requested to initiate the design for a facility that had the capabilities to convert plutonium nitrate solutions to oxalate, oxide, and finally metal, and the capabilities to fabricate the metal into weapon components. The design of PFP was initiated in 1947, construction was initiated in 1948, and hot operations were initiated in July1949 (HNF-EP-0924, History and Stabilization of the Plutonium Finishing Plant (PFP) Complex, Hanford Site). The 234-5Z facility became the major receiver of the plutonium product from 231-Z, REDOX, and PUREX. The construction of the 234-5Z facility represented a major expansion of Hanfords role in nuclear weapons production. This facility was designed to convert plutonium



nitrate into metal and then into weapons components. Many Hanford documents refer to the collection of Z facilities supporting plutonium finishing activities as Z Plant. As plutonium processing capabilities expanded in areas of scrap recovery and waste treatment over the years, the expanded plutonium processing operation was referred to as the Plutonium Finishing Plant. The PFP Complex was designed to be a self sufficient stand-alone plant for the conversion of plutonium nitrate into oxide and metal products, with all necessary scrap recovery, analytical, and developmental capabilities. The functional capabilities included such things as: Chemical processing for conversion of plutonium nitrate to oxide and metal Metallurgical processing for fabrication of weapon components Scrap processing systems for recovery of plutonium Impure nitrate purification processing Waste treatment processing Radiochemical/chemical analytical laboratories Development laboratory Secured plutonium storage (vaults and vault type rooms) Maintenance and utility support systems.

The PFP processed more than 95% of the plutonium produced at Hanford and a more thorough discussion of its process systems and processing history is provided in Sections 4.3 to 4.6. In the spring of 1962, PFP was fully engaged in conversion of plutonium nitrate solutions into metal buttons and on into formed weapons components. Scrap recovery to support this work was conducted in the RECUPLEX facility. The work was occurring at the height of the Cold War and all available site reactors and separations plants were operating. The RECUPLEX criticality incident in April 1962 (HW-74723) interrupted the production cycle because PFP scrap forms could not be processed on an as-generated basis. The most immediate problem involved dealing with filtrate from the oxalate precipitation step. This liquid stream contained an average of about two percent of the total plutonium in the feedstock to the plant. From about two weeks following the criticality event, substantial efforts were made to resume processing plutonium nitrate to metal. The temporary resolution for filtrate involved expedited construction of several hundred batch cans of nominal 10-liter capacity each, and transport of button line filtrate in those cans, by truck to the REDOX and PUREX canyon fuel processing facilities for rework in their processes. That mode of accommodating the filtrate continued until an ion-exchange capability was installed in room 232 of the 234-5Z Building. By the end of November 1962, the ion exchange equipment had picked up the filtrate processing load. Scrap solutions continued to be sent to PUREX and REDOX for recovery until PRF was started in 1964. Several additional plutonium facilities were also established at the Hanford Site. Interest in the use of plutonium for commercial nuclear reactors grew in the 1950s, which led to the construction of the Plutonium Fabrication Pilot Plant (308/308-A Bldg) in 1960 for plutonium reactor fuel development activities. This facility, which was located in the 300 Area, included Official Use Only 26


numerous plutonium metallurgical capabilities to support plutonium metal and alloy reactor fuel development studies, and plutonium oxide fuel fabrication capabilities to support plutonium oxide fuel development studies. This facility operated from 1960 until 1992. Prior to restart of PUREX in the early 1980s, it was decided to expand PUREX processing capabilities. This processing expansion included the ability to convert the plutonium nitrate to plutonium oxide in a new processing system to be installed in N-Cell of the PUREX canyon. This plutonium processing system became known as the PUREX Oxide Line, Project B-175, and the N-Cell Line (see section 5.4).

4.3

231-Z ISOLATION FACILITY PLUTONIUM OPERATION

The 231-Z facility operated from January 1945 until January 1957 to purify Pu (NO3)4 solutions that were produced at the T and B Plants (plutonium bismuth phosphate process) and the REDOX facility (methyl isobutyl ketone solvent extraction process). The 231-Z operations were fairly straightforward. The generalized plutonium peroxide flow sheet used at the 231-Z Facility is depicted in Figure 10 [HW-29200, Plutonium Purification and Fabrication Technical Manual, HW-26365, Brief Summary of Separations Processes, HW-10475]. The feed stream to 231-Z was plutonium in a lathanium fluoride carrier from the 224-T or 224-B facility (operational December 1944March 1956) and B Plant (operational April 1945August 1952), which contained an excessive quantity of lanthanum (La). The plutonium nitrate from REDOX (operational September 1951April 1967) that did not meet product specification for 234-5 Building was also processed at the 231-Z Facility. Once the REDOX plutonium nitrate product started meeting 234-5Z feed specification, the REDOX material went directly to the 234-5 Building. For the material from T and B plants, two peroxide precipitations were used to achieve a final product nitrate (at least 95% pure). The feed solution to 231-Z was first filtered and then treated with ammonium sulfite to reduce any hexavalent plutonium that might be present, and ammonium sulfate and hydrogen peroxide were added to precipitate plutonium peroxide. The precipitate was washed, filtered, and dissolved in nitric acid, with the corresponding decomposition of the peroxides which yielded a plutonium nitrate solution. A second precipitation was performed to get a product that would meet final product specifications. If the product was to be shipped offsite, the final plutonium nitrate solution was concentrated in a still to a thick paste. If the product was to be sent to the 234-5 Building for conversion to plutonium oxide, a final oxalate precipitation was performed. The oxalate product slurry was filtered to collect the precipitate and the filtrate was collected in a vacuum receiver (CT-1). When the RG Line Task I process was operational (1949early 1950s) plutonium nitrate was shipped to the 234-5 Building. The filtrate from 231-Z processing that was recycled to the 224-T Concentration Facility was treated with 40% NaNO2 to react with excess peroxide and finally with 4% KMnO4 until a permanent coloration appeared. All the various filtrate streams from first, second, etc., precipitations and washes were combined together and sent back for plutonium recovery. Typically, 6.38 kg of CT-1 solution contained on the order of 0.12 kg Pu, and 2.13 kg La. Official Use Only 27


The 234-5 Building production was started up in 1949. Initially 231-Z supplied a plutonium paste to the RG Line. When the RMA Line replaced the RG Line, the feed was in the form of plutonium III oxalate and was later changed to a Pu(IV) oxalate. [HW-10475; HW-29200, Plutonium Purification and Fabrication Technical Manual] The La(NO)3-Pu(NO)4 solution (F-10-P) sent to the Isolation Building (231-Z) from the T and B Plants contained about four times as much La as Pu and also included smaller amounts of other impurities (K, Ca, Bi, Fe, Cr, etc.). The plutonium nitrate product solution was transferred via a PR can to the Isolation Building (231-Z) at a nominal concentration of 20-40 g Pu/L nitric acid solution. The REDOX process started-up in January 1952. The plutonium nitrate product (III-BP) was sent to the 231-Z Facility for further purification. The REDOX product contained about 10-20 g/L Pu. Initially at least, the REDOX plutonium was 80-90% Pu(VI) and the valence was adjusted to Pu(IV) before making plutonium (IV) oxalate precipitate. The REDOX process recovered both plutonium and uranium from a solvent extraction process. The uranium and plutonium nitrate streams were further purified and the final plutonium product stream was transferred to the 231-Z facility for further purification. Once the REDOX plutonium product met the feed specifications for the 234-5 Building, the plutonium product from REDOX was transferred directly to the 234-5Z Building. Some plutonium scrap solution from the 234-5 Building operations was transferred for recovery and recycle via a 231-Z purification process [HW-19991, Final Report Production Test 234-2 Recycle of Skull Solution to the Isolation Process, HW-29200]. The skull of residual plutonium metal removed from the pouring crucible was dissolved in nitric acid in laboratory equipment to produce a relatively pure plutonium nitrate solution. The product solution was sent to the 231-Z operation where the solution was adjusted to 231-Z first cycle flow sheet concentrations and processed normally through 231-Z. Available records are incomplete, but by 1952 a plutonium oxalate process (Task I) capability was operational at the 234-5 Building. The 231-Z Facility was supplying plutonium oxalate cake for Task II from the T Plant bismuth-phosphate recovery. The REDOX plutonium nitrate product would have met the 234-5 plutonium nitrate feed specification by 1953 (assumption) and have been transferred directly to the Remote Mechanical A (RMA) Task I (batch oxalate precipitation) operation.



Figure 10. Historical Flowsheet for 231-Z

4.4

PFP PRODUCTION LINES

A wide variety of plutonium processing and handling capabilities were established in the PFP facility during its more than 50 year life to handle a significant array of plutonium material types and to handle plutonium having a wide spectrum of isotope distributions. A significant overview of PFP history and its process systems has been documented by Gerber (HNF-EP-0924), and a detailed overview of its operating history, production quantities, and scrap generation and recovery activities has been documented by Hoyt and Teal [HNF-22064, Plutonium Finishing Plant Operations Overview (19492004)]. Initial operations at the PFP were focused at the conversion of pure weapon grade plutonium nitrate solutions into plutonium metal and subsequent fabrication into weapon components. Operations that were directly related to the production lines were designated with Task numbers, see Table 4. Historical information in operations reports usually refers to work activities by these Task numbers, as is done in some of the tables presented in this report.



Table 4. Historical Task Numbers and Task DescriptionsTask Number I II III IV V VI VII VIII Task Descriptions Oxalate Precipitation (includes infiltration and calcinations) (also referred to as Purification or Wet Chemistry) Hydrofluorination (Dry Chemistry) Reduction (to metal) Ingoting and Casting Machining (Shaping) Cleaning Coating Final Inspection

There were three separate generations of plutonium conversion lines installed and operated within PFP: Rubber Glove (RG) Line, Remote Mechanical A (RMA) Line, and Remote Mechanical C (RMC) Line. Another line, the Remote Mechanical B (RMB) Line, was also installed after the RMA Line. However, this line became obsolete and was removed before ever initiating hot operations. The initial plutonium metal production and weapon component fabrication line, the RG Line, ran from 1949 until ~1953. The RG Line was a hands-on batch operated system; and after a few years of difficult operation it was replaced with the remote mechanical RMA Line. The RMA Line became operational in 1952 and proved so successful that the RG Line was phased out. As plutonium production requirements accelerated, a second metal production and weapons component fabrication line was installed to supplement the RMA Line capabilities. This new process, the RMC Line, became operational in 1960. The RMA Line was eventually converted to an oxide line in 1968 when the hydrofluorinator was converted to a second stage calciner. Subsequently this line became to be known as the RMA Oxide Line and it remained operational through 1979. The RMC Metal Line operated through 1973 and then remained shutdown until its final campaigns during 19851989 time period. Plutonium production activities significantly diminished in the 1970s and 1980s, after which attention focused on the stabilization and safe storage of remaining plutonium inventories. Thermal stabilization of plutonium solids began in the early 1990s. A Thermal Stabilization and Packaging system was subsequently installed in 234-5Z in the mid 1990s and another was installed in the 2736-ZB Facility in ~2000. Solutions were processed through either batch Mg(OH)2 precipitation and calcination or batch plutonium(IV) oxalate precipitation and calcination in 234-5Z during 2003. All materials in inventory requiring stabilization and packaging to the new storage and stabilization standard were so treated by April 2004, at which time efforts on legacy holdup removal, facility cleanout and demolition became the central mission focus.



A summary of the more significant PFP missions and activities is provided in Table 5, along with their timeframes of operation. These activities, while not all-encompassing, provide a realistic depiction of the work performed during PFPs more than fifty-year lifetime. Additional non-production operations such as analytical work, development work, and plutonium storage supported all of these activities. Many of the non-defense missions involved small amounts of plutonium, various plutonium compounds, and plutonium having a wide variety of Pu-240 isotopic content. Table 5. Overview of PFP Plutonium Processing Activities, 1949 to 2004Overview of PFP Plutonium Processing (Time Period 1949-2004) Processing Activity Processing Involving Hanford Generated Pu Weapons Grade Material Production RG Line Weapons Grade Material Production RMA Line Weapons Grade Material Production RMC Line High Pu-240 Oxide and/or Metal RMA Line High Pu-240 Oxide and/or Metal RMC Line High Pu-240 Component Fabrication Research Special Oxide Production for EURATOM (Hanford activities) PRTR 20% Pu-240 Nitrate Conversion to Nitrate, Oxide, Metal Nitrate Blending for SEFOR Fuel (13&20% w WG to 8%) Shippingport 24% Pu-240 Nitrate Conversion to Nitrate, Oxide, Metal BNW Criticality Safety Lab FFTF Cores 1&2 Oxide in RMA Line High Pu-240 Oxide for SRS Cf Deep Burn Experiment & Other Blend SRS & Hanford Oxide in RMC Line, FFTF Cores 3&4 SRS 3% Metal Burn To Oxide, Dissolve, Blend w FG, to WG Metal Subtotal First Generation Scrap Recovery & Stabilization Processing Pu Recycled From RECUPLEX SX Pu Recycled From PRF SX Pre-DNFSB 94-1 Stabilization Activities DNFSB 94-1 Stabilization & Packaging Activities (234-5Z) DNFSB 94-1 Stabilization & Packaging Activities (2376ZB) Solution Stabilization (Mg hydroxide & oxalate batch precipitations) 10 micron 1kg Particle Size microns 40-100 Comments No filter used at REDOX 100% went to tank farm Only 20% of material made it past 40 micron filter to tank farm Sieved with 325 mesh use RMA PSD- 4 Distributed 50% to each tank

Nitrite with 1Kg based on 1% oxide loss of 100kg entrainment Nitrite with 2Kg based on 1% oxide loss of 200kg entrainment Oxide 280 g based on 4.2% lost of 6.6 kg 53 g based on 0.8% lost of 6.6 kg 850 g based on 4.2% of 20.3kg 160 g based on 0.8% of 20.3 1820 g based on 4.2% of 43.4kg

A-105

8-11 g/cc

2 X 0.2 = 0.4 Kg

40-100

S-107

8-11 g/cc 45-90% based upon PFP oxide PSD

280 X 0.9 = 252

10-40

Oxide

S-111 and 8-11 g/cc 45-90% based 53 X 0.9 = 48 SX-114 upon PFP oxide PSD C-102 8-11 g/cc 45-90% based upon PFP oxide PSD 8-11 g/cc 45-90% based upon PFP oxide PSD 850 X 0.9 = 768 160 X 0.9 = 144 1820 X 0.9 = 1640

10-40

Oxide

10-40

Oxide

BX-101

10-40

Oxide

C-104 8-11 g/cc 45-90% based tranfered upon PFP to AN-101 oxide PSD in 2010 B-101 8-11 g/cc 45-90% based upon PFP oxide PSD

10-40

98% is in AN-101 and 2% in C-104 1600 and 40 g respectively

Specialty Fuels 1970-72 PUREX

Oxide

350 g based on 0.8% of 43.4

350 X 0.9 = 315

10-40



Table 38. Likely Plutonium Oxide Discharges to the Tank FarmsSource Tank Pumpouts /Truck Transfers 216-Z-8 Chemical Form Oxide/ soluble Quantity Lost 290 grams of Pu in liquid and 142 grams oxide from PFP based upon 10% entrainment Tank Farm Location TX-109 Density 142 g was 811 g/cc Percent > 10 micron Of the 142 g, 50% is oxide from precipitate and based upon PFP oxide PSD of 4590% Quantity > 10 micron 71 X 0.9 = 64 g Particle Size microns 50% is 1040 micron and 50% is 40-100 micron Comments 50/50 mixture of PFP burnt metal and oxide based upon slag and crucible source

Truck Transfer 241-Z-361

Oxide/ less than 40 grams soluble/PuF of Pu in liquid and 4 448 grams oxide from PFP assuming 0.5% entrainment

TX-101

448 g 45-90% based was upon PFP 8-11 g/cc oxide PSD

448 X 0.9 = 0.403 g

10-40 micron

A 0.5% entrainment used since Z-361 was trying not to remove solids

6.0

TANK FARM CHARACTERIZATION AND CHEMISTRY

This section discusses the chemistry of plutonium in the tank farm. Five papers were written by Calvin Delegard of Pacific Northwest National Laboratory on Pu-chemistry in the tank farms can be found in Appendix C of this report. These papers are denoted the Delegard Papers here after the author. The main body of the report in Section 6 covers plutonium inventory and characterization in the tank farm. The first Delegard paper is Ostwald Ripening and Its effect on PuO2 Particle Size in Hanford Tank waste, which discusses the unlikelihood of appreciable growth of PuO2 particles in the Tank Farms under tank farm conditions. The second Delegard paper is Metathesis of Plutonium(IV) Oxalate and Plutonium(III)/(IV)Fluoride in Alkaline Medium to Form PuO2.xH2O, which shows that plutonium(IV) Oxalate and plutonium(III) and (IV) Fluoride cannot survive in the tank farm, and thus are not of concern. The third Delegard paper is called Plutonium(IV) Oxide from Burnt Plutonium Metal, which shows that plutonium metal can survive in the tank farm even though it is not thermodynamically stable because of slow conversion kinetics. The 4th Delegard paper is called Coprecipitation from Nitric Acid Media of Plutonium(IV) with Uranium(VI) in Alkaline Solutions, which shows that plutonium can co-precipitate with uranium when acidic solutions containing both metals are neutralized with sodium hydroxide. This paper also explains the neutralization process used for treating soluble plutonium at all fuel processing facilities.



The fifth Delegard paper, Interfacial Crud Disposition in Alkaline Tank Waste, discusses interfacial crud formation and decomposition. As discussed in Section 4, interfacial Crud is a possible mechanism for the translocation of large plutonium particles from PFP to the tanks.

6.1

INTRODUCTION TO TANK FARMS CHARACTERIZATION

This section discusses the characterization of the tanks that received waste that could have contained large, dense plutonium particles, such as PuO2. The two tanks that will be discussed are SY-102 and TX-118. The other two tanks receiving large quantities of PFP waste (TX-105 and TX-109) have not been sampled previously, so there is no sample data to discuss for these tanks. Tanks that received waste from non-PFP sources (see section 5) have too little large plutonium particles in them relative to their total plutonium inventories for a discussion of the plutonium inventories to be useful. As a background for this section, a Pu inventory for the PFP waste receiver tanks is reported here. The Best-Basis Inventory reports for SY-102, TX-105, TX-109, and TX-118 report the quantity of Pu-238, 239 and 240 (Disselkamp, 2009c;d;e; Place, 2011). Table 39 contains the cur

Documents

Review of Plutonium Oxide and Hanford Tank Farms Report