Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
© 2015 Electric Power Research Institute, Inc. All rights reserved.
Carola Gregorich, Dr. - Senior Technical Leader Daniel Wells, PhD – Program Manager, Chemistry
17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems –
Water Reactors Ottawa, ON, Canada, August 10, 2015
In-Plant Gamma Spectrometry for Source Term Control
Monitoring Review of US Experience
2 © 2015 Electric Power Research Institute, Inc. All rights reserved.
In-Plant Gamma Spectrometry
Captures qualitatively and quantitatively isotopic data Can be done at a point in time and/or in time sequence
Adaptable to purpose and environment of measurement
Provides diagnostic and forensic data for asset protection and radiation field reduction
3 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Why Asset Protection Affects Radiation Field Generation
Soluble Species
Particulates Insoluble
Desorption
Sorption
Dissolution
Precipitation
Example Activation [Decay] 59Co (n,γ) 60Co [5.27 yrs]
58Ni (n,p) 58Co [70 days]
Rad
iatio
n Fi
eld
Stellite Replacement Low-Co Alloys
SD/SU Protocol Coolant Cleanup
Cor
e/Fu
el D
esig
n Fu
el C
lean
ing
Chemistry Regimes: Zn, pH, H2, Pt
Chemical/Physical Decon Surface Passivation
AL
AR
A
Comprehensive mechanistic understanding of corrosion, corrosion product release, and activity incorporation
on ex-core surfaces remains elusive under
multiple change implementation conditions
4 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Elusive Details of Surface Activity Incorporation
Base Metal (virgin material)
Metal Oxide Surface Protective Film
Permanent Corrosion Product Oxide Layer
Transient Corrosion Product Particulate Layer
Bulk Coolant
Release and incorporation mechanisms are controlled by base metal, coolant chemistry, temperature, pressure, and flow – Nickel and iron typically go into solution, while chromium does not – Interfacial coolant establishes saturation equilibrium with bulk coolant in
boundary layer – Temperature affects solubility – Ferrites & other species
form when precipitation occurs Particulate suspension
changes with flow Incorporation of activated
species depends on its chemical and physical properties as much as on those of the surface
5 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Standard Radiation Monitoring Programs
PWR: AUXS Locations – added in 2014 Revision CVCS-LD – CVCS letdown line in aux building CVCS-RL – CVCS return line in aux building CVCS-HX – Non-regenerative CVCS heat exchanger
RHR-LD – RHR letdown line in aux building RHR-RL – RHR return line in aux building RHR-HX – RHR heat exchanger
PZR1 – Horizontal section of Pressurizer Surge Line (hot leg tap) PZR2 – Horizontal section of Pressurizer Spray Line (cold leg tap) PZR3 – Horizontal section of Pressurizer Spray Line (head)
RFB – Refueling bridge, near operator RVCH – Reactor vessel closure head
B RECIRC PUMP A RECIRC PUMP
'A' RISER30o
'B' RISER60 o
'C' RISER90 o
'D' RISER120o
'E' RISER150o
'F' RISER210o
'G' RISER240 o
'H' RISER270o
'J' RISER300 o
'K' RISER330 o
'B' SUCTION0
o
'A' SUCTION
180 o
FCV 68-35FCV
68-33
FCV 68-1
FCV 68-3
FCV 68-79
FCV 68-77
HCV 74-69
FCV 74-49
HCV 74-55
584' grating
563' grating
550' floor
C/L 556' - 8"
C/L 552' - 4"
C/L 580' - 9"
22' Discharge Header
593' - 4"591'11" WHIPRESTRAINT
591'11" WHIPRESTRAINT
N1B
N2E N2D N2C N2B N2A N2K N2J N2H N2G N2F
1AD
5A
4A
3A
2A1A
2AS
N1A
1BD
5B
4B
3B
2B
1B
2BS
XX OR XXX DENOTES SURVEY POINT, POINTS SHOULD BE MARKED ON MIRROR INSULATION
B RECIRC PUMP A RECIRC PUMP
'A' RISER30o
'B' RISER60 o
'C' RISER90 o
'D' RISER120o
'E' RISER150o
'F' RISER210o
'G' RISER240 o
'H' RISER270o
'J' RISER300 o
'K' RISER330 o
'B' SUCTION0
o
'A' SUCTION
180 o
FCV 68-35FCV
68-33
FCV 68-1
FCV 68-3
FCV 68-79
FCV 68-77
HCV 74-69
FCV 74-49
HCV 74-55
584' grating
563' grating
550' floor
C/L 556' - 8"
C/L 552' - 4"
C/L 580' - 9"
22' Discharge Header
593' - 4"591'11" WHIPRESTRAINT
591'11" WHIPRESTRAINT
N1B
N2E N2D N2C N2B N2A N2K N2J N2H N2G N2F
1AD
5A
4A
3A
2A1A
2AS
N1A
1BD
5B
4B
3B
2B
1B
2BS
XX OR XXX DENOTES SURVEY POINT, POINTS SHOULD BE MARKED ON MIRROR INSULATION
BWR: AUXS Locations – reinstated/optimized in 2014 Revision
2014 Revisions capture also the locations of concern to radiation protection
6 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Available Data Sets from U.S. Fleet
BWR PWR
More & systematic data are available for BWR fleet
7 © 2015 Electric Power Research Institute, Inc. All rights reserved.
What Can Be Concluded from Available PWR Data?
Limited data set, often captured to assess specific change, i.e., not comprehensive, and general conclusion may have limited applicability: Cobalt activities are higher in regions of lower temperature. Cobalt-58 activities are generally higher than Co-60 activities. Hot leg Co-58 and Co-60 activities remain constant over life of plant. Crossover/cold leg Co-58 and Co-60 activities decrease over life of plant.
8 © 2015 Electric Power Research Institute, Inc. All rights reserved.
What Do the Data of BWR Reactor Recirculation System Tell?
Maximum in Bin
Measurement Data In Bin
Co-60 Median
Co-60 Average
Co-60 Standard Deviation
10 140 4.88 4.90 2.24
20 29 13.78 13.85 2.57
30 5 24.87 24.39 1.61
40 3 34.60 33.81 1.50
50 1 45.95 45.95
Plant design and operation resulting in Co-60 Surface Activities < 2.7 µCi/cm2 – identify desired conditions > 7.2 µCi/cm2 – identify detrimental conditions to achieve lower radiation fields
9 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Today’s U.S. BWR Coolant Operating Regimes Not Well Characterized
Num
ber o
f Gam
ma
Scan
Cam
paig
ns in
U.S
. BW
Rs Implementation of zinc injection
and hydrogen water chemistry was proportionally followed
Implementation of original noble metal injection followed on demonstration principle
? Implementation on online injection of platinum follow at discretion
Data are needed to • understand today’s corrosion
and activity incorporation • ensure asset protection, and • lower radiation fields
10 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Exploring Data – Seeing Faster, Clearer & More
Uncovering relationships not readily found by traditional methods/expertise Faster deeper dive into data exploration
Traditional Data Exploration: Scatter = No Conclusion = No Opportunity
Data Exploration with Tools of Data Science: Clear Grouping = Conclusions lead to Opportunities
11 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Diagnostic Tools of Data Science – Decision Tree Example
Confirming/disputing current assumptions and hypothesis
Identifying factors currently not considered
Original Condensate Filter Demineralizer Design
Main Condenser Tubesheet Material
Operational Year Zinc Injection Start
Operational Year Gamma Scan
12 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Diagnostic Tools of Data Science – Cluster Analysis Example
Puzzling – two very distinct clusters Insights do not reflect current understanding of chemistry regime effect on Co-60 incorporation
Limitation of Dataset?
13 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Diagnostic on BWR Gamma Scan Data to Derive Insights on Radiation Field Control
Parameter Set (Inputs) CRT Decision Tree
CHAID Decision Tree Two-Step Cluster
Basic Plant (7) 1. Original condensate cleanup design
2. BWR class
1. Original condensate cleanup design
2. Presence of fuel failure
1. BWR class 2. Number of control rod
blades Number of clusters - 5
Plant Materials (10) 1. Main Condenser Tubesheet
2. RCS StelliteTM surface area
1. Reactor recirculating System Piping
2. RCS StelliteTM surface area
1. Moisture Separator 2. Reactor recirculating
System Piping Number of clusters - 4
Chemistry (5) 1. Operational OLNC year 2. Operational NMCA Year
1. Operational HWC year 2. Operational DZO Year
1. Operational DZO year 2. Operational NMCA Year Number of clusters - 2
Operational (13) 1. Feedwater to condensate flow ratio
2. Core power, kWt/L
1. RCS liquid mass at full power, lbs
2. Average condensate temperature
1. Average condensate temperature
2. Core flow Number of clusters - 4
Top Two Importance Predictors
14 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Diagnostic on BWR Gamma Scan Data to Derive Insights on Radiation Field Control
Top Step – Cluster Analysis Top-5 dominant clusters shown
Kohonen – Cluster Analysis
Attention:
Colors Do Not relate.
15 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Validating Feasibility of Data Science Exploration Approach Co-60RRS-BRAC = 1.91 YOLNC - 0.62 YHWC + 11.15 RFW/Cd – 0.10 TAvCd – 6.5E-5 MRCSLq + 0.20 AStellRCS + 1.12 AStellCRB
+ 2.30 TCoreIn + 0.88 PCore + 2.75E-2 YOPS – 764.9 R2 = 0.633
Parameter Symbol Plant A Plant B Plant C Cycle N Plant C Cycle N+5
Operating year OLNC implemented YOLNC 27.5 30.8 26.1 26.1
Operating year HWC implemented YHWC 15.795 8 3.1 3.1
FW-to-Condensate flow ratio RFW/Cd 1.433 0.943 1 1
Avg. Condensate temperature, F TAvCd 115 115 110 110
RCS liquid mass at full power, lbs MRCSLq 594300 440000 471000 471000
StelliteTM surface area in RCS, sqft AStellRCS 162.639 118.3 118.3 118.3
StelliteTM surface area in of CRB, sqft AStellCRB 49.751 38.5 38.5 38.5
Coolant core-In temperature, C TCoreIn 274 276 278 278
Core power, kWt/L PCore 48.7 49.2 50.1 50.1
Operational year at time of Gamma Scan YOPS 29 23 35 45
Co-60 surface activity, measured, µCi/cm2 7.3 6.2 5.15 To be measured
Co-60 surface activity, calculated, µCi/cm2 5.8 4.9 3.8 4.1
16 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Validating Feasibility of Data Science Exploration Approach Co-60RRS-BRAC = 1.91 YOLNC - 0.62 YHWC + 11.15 RFW/Cd – 0.10 TAvCd – 6.5E-5 MRCSLq + 0.20 AStellRCS + 1.12 AStellCRB
+ 2.30 TCoreIn + 0.88 PCore + 2.75E-2 YOPS – 764.9 R2 = 0.633
Regression analysis based on parameter identified in exploratory decision tree and cluster analysis yields a potentially feasible approach to predict Co-60 incorporation in to ex-core surfaces on plant specific basis
17 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Isotopic Data for Asset Protection and Radiation Field Control Gamma Spectrometry
– Captures qualitatively and quantitatively isotopic data – Can be done at a point in time and/or in time sequence – Adaptable to purpose and environment of measurement – nuclide identification capabilities make it a diagnostic and forensic tool
Evaluation of gamma spectrometry data linked to plant design, materials, and operational information through data science tools to – Uncover previously hidden relationships – Identify new opportunities for asset protection and radiation field control – Enable improvements in performance indicators, utilization, and cost efficiency
U.S. gamma scan data set is limited
Available U.S. data for ex-core surface activities do not reflect adequately current plant operation regime
18 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Together…Shaping the Future of Electricity