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Radioactive Waste Overview
• High Level Radioactive WasteThe U.S. NRC describes high-level radioactive wastes as the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes take one of two forms: – Spent (used) reactor fuel when it is accepted for disposal – Waste materials remaining after spent fuel is reprocessed
Spent nuclear fuel is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed. However, it is still thermally hot, highly radioactive, and potentially harmful. Until a permanent disposal repository for spent nuclear fuel is built, licensees must safely store this fuel at their reactors.
Low Level Radioactive Waste
• Classes of Waste– Class A– Class B– Class C
• Three existing low level radioactive waste disposal facilities– Barnwell, SC– Hanford, WA– Clive, UT
Low Level Radioactive Waste
• Waste is disposed in Low Level Disposal Facilities.
Low Level Radioactive Waste
• Low Level Radioactive Waste is encapsulated either by solidification or placement in High Integrity Containers.
High Level Radioactive Waste
Fuel Rods Filled With Pellets Are Grouped Into Fuel
Assemblies
Fuel Assemblies Cool Temporarily in Used Fuel Pools
Dry Fuel Storage at Plant Sites
Temporary Dry Fuel Storageat Power Plant Site
Dry Fuel Storage Projects
• ENERCON Services has provided engineering services for 18 Dry Fuel Storage Projects throughout the US.
Dry Fuel Storage Projects
• Dry Fuel Storage Projects include design and engineering for:
– Storage Pad– Facility Security– Electrical– Federal Licensing– Local and State Permitting– Cask Heavy Load Lifting
Transportation Containers Are Strong and Safe
Transportation Casks Have Been Tested
Container Loaded on a Truck…
… And Crashed at 80 MPH into a Concrete Wall
Container Broadsided by Locomotive Traveling at 80
MPH
Containers Survived Incineration Tests
Containers Passed Every Test
NRC Concludes Shipping Even Safer Than Previously
Thought
At the Repository, Fuel Will Be Transferred to a Special
Disposal Container
Yucca Mountain Being Considered As Disposal Site
Yucca Mountain Being Considered As Disposal Site
Seven Miles of Tunnels Built in Yucca Mountain
Yucca Mountain Has Been Thoroughly Investigated
President Recommends Yucca Mountain
New Nuclear Power and Climate Change:
Issues and Opportunities
Lunch Keynote Presentation
William Sweet
Senior News Editor
IEEE Spectrum
New Nuclear Power and Climate Change:
Issues and Opportunities
Student Presentation
Ashish K Sahu and Sarina J. Ergas
University of Massachusetts - Amherst
Perchlorate Reduction in a Packed Bed Bioreactor Using
Elemental Sulfur
Ashish K Sahu and Sarina J. Ergas
Background
• Perchlorate (ClO4-)
– Stable
– Non reactive
• Trace levels of Perchlorate
– Disruption of hormone uptake
in thyroid glands
Geographic Contamination
• No National Standards• MCL set by the
Commonwealth of Massachusetts
(2 g/L)• California advisory
levels (6 g/L)• Other states (NY, NV,
AZ, CO, TX) 18 g/L Ref: ewg.org
Sources of Perchlorate
• Natural– Atmospheric Sources– Chilean nitrate fertilizer
• Anthropogenic– Missiles, Rockets – Fireworks– Leather Tannery Industries– Fertilizers
• Physical Processes
• Chemical Processes
• Biological Processes
• Combination of the above
Treatment Processes
Perchlorate Treatment Processes
Physical Destructive Process
ChemicalBiological
GAC
RO/NF
Electrodialysis
CC-ISEP Bioreactors
Hybrid Technologies
Bio-remediation
Phytoremediation
IX
Others
Others (MBR)CSTR PFR
Reducing metals
Outline
• Biological Perchlorate Reduction
• Use of Elemental Sulfur
• Experimental Protocol
• Results
• Conclusions
Biological Perchlorate ReductionPrinciple: Microorganisms convert perchlorate to chloride
Heterotrophic microorganisms
• Use organic carbon as their carbon source
• Electron donors are methanol, lactate, ethanol, wastewater
Autotrophic
microorganisms• Use inorganic carbon
as their carbon source eg: NaHCO3
• Electron donors are S, Fe0, H2
Use of Elemental Sulfur
2.87 S + 3.32 H2O + ClO4- + 1.85 CO2 + 0.46 HCO3
- + 0.46 NH4+ →
5.69 H+ + 2.87 SO42- + Cl- + 0.462 C5H7O2N
• Electron Donor: Elemental Sulfur• Electron Acceptor: Perchlorate• Carbon Source: Bi-carbonate• Low biomass production • Low nutrient requirements• Anoxic conditions• Alkalinity destroyed
Advantages of Elemental Sulfur
• Waste byproduct of oil refineries
• Excellent packing media
• Relatively inexpensive and easily available
• Applications in packed bed reactors and permeable reactive barriers
Objectives
– Enrich a culture of Sulfur Utilizing Perchlorate Reducing Bacteria (SUPeRB)
– Investigate the use of packed bed bioreactors to treat perchlorate contaminated waters by SUPeRB
– Test the bioreactor for varying operating conditions
Batch Culture Enrichments
• Denitrification zone of Berkshire wastewater treatment plant, Lanesboro, MA
• 5mg/L ClO4-, So and oyster shell, nutrients in
groundwater
• Analytical Techniques– pH
– ClO4- concentration using IC (EPA method 314.0)
Batch Culture Enrichment (SUPeRB)
0.0
1.0
2.0
3.0
4.0
5.0
0 100 200 300 400
Days
ClO
4- mg
/L
Packed Bed Reactor
• Reactor inoculated with SUPeRB
• Media: Elemental Sulfur pellets (4 mm), oyster shell (3:1 v/v)
• Volume: 1 liter
• Ports: 5 ports
Packed Bed Reactor OperationExperimental
PhasePerchlorate
concentration mg/L
EBCT hrs
Recirculation RatioQR/Q
So particle
size
Phase I 5-8 13-100 Intermittent at(40-1,500)
4 mm
Phase II
Reactor 1 0.08-0.12 25-30 50-1,000 4 mm
Reactor 2 0.08-0.12NO3
--N (10 mg/L)8-30 None 4 mm
Reactor 3 0.08-0.12 8-30 None 0.85 mm
Bioreactor Performance-Phase II(Effect of Empty Bed Contact Time (hrs))
020406080
100120140
0 50 100 150
Days
ClO
4- g
/L
Influent Effluent
30 15 12 8
Bioreactor Performance-Phase II(Effect of Empty Bed Contact Time)
7589 87
96
0
20
40
60
80
100
120
28 15 11 7.5
Empty Bed Contact Time (hrs)
Ave
rag
e %
ClO
4- rem
ova
l
Bioreactor Performance-Phase II(Effect of sulfur size particles)
6560
90
0
20
40
60
80
100
21 7.6 4
Empty bed contact time (hrs)
Ave
rag
e %
ClO
4- re
mo
val
Bioreactor Performance-Phase II(Effect of Nitrate on Perchlorate
Removal)
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30 35
Distance cm
NO
3- N
mg
/L
0
20
40
60
80
100
ClO
4- g
/L
Nitrate Perchlorate
Summary
• SUPeRB reduced ClO4- from 5 mg/L to <0.5
mg/L in 15 days using S0 and OS
• High levels of perchlorate (5-8 mg/L) were successfully reduced to < 0.5 mg/L in the bioreactor at an EBCT of 13 hours
• Low levels of perchlorate (80-120 g/L) were reduced to < 4 g/L at an EBCT of 8 hours
Summary…
• Presence of nitrate did not inhibit perchlorate reduction
• Perchlorate reduction was somewhat independent of media particle size
Applications and Future Work
• Pilot scale of system for perchlorate remediation
• Ex-situ remediation
• In-situ remediation by Permeable Reactive Barriers (PRBs)
Acknowledgements
• Water Resources Research Center (WRRC), TEI at UMass-Amherst
• Massachusetts Technology Transfer Center (MTTC) for commercial potential
• Advisor: Dr. Sarina Ergas• Teresa Conneely, Department of Microbiology
for FISH and microbiology analysis • Tach Chu and Charlie Moe (High School) for
culture and bioreactor maintenance