Radioactive Waste Overview
• High Level Radioactive Waste
The 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 Storage
at 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
Ref: ewg.org
• No National
Standards
• MCL set by the
Commonwealth of
Massachusetts
(2 mg/L)
• California advisory
levels (6 mg/L)
• Other states (NY,
NV, AZ, CO, TX)
Sources of Perchlorate
• Natural
– Atmospheric Sources
– Chilean nitrate fertilizer
• Anthropogenic
– Missiles, Rockets
– Fireworks
– Leather Tannery Industries
– Fertilizers
Treatment Processes
•
•
•
•
Physical Processes
Chemical Processes
Biological Processes
Combination of the above
Perchlorate Treatment Processes
Physical
Destructive Process
Hybrid Technologies
Biological
Chemical
GAC
RO/NF
Bioreactors
CC-ISEP
Phytoremediation
Reducing metals
IX
Electrodialysis
Others
Others (MBR)
CSTR
Bio-remediation
PFR
Outline
•
•
•
•
•
Biological Perchlorate Reduction
Use of Elemental Sulfur
Experimental Protocol
Results
Conclusions
Biological Perchlorate Reduction
Principle: 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
-
Batch Culture Enrichment
(SUPeRB)
5.0
ClO4- mg/L
4.0
3.0
2.0
1.0
0.0
0
100
200
Days
300
400
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 Operation
Perchlorate
concentration
mg/L
EBCT
hrs
Recirculation
Ratio
QR/Q
So
particle
size
5-8
13-100
Intermittent at
(40-1,500)
4 mm
Reactor 1
0.08-0.12
25-30
50-1,000
4 mm
Reactor 2
0.08-0.12
NO3--N (10 mg/L)
8-30
None
4 mm
Reactor 3
0.08-0.12
8-30
None
0.85 mm
Experimental
Phase
Phase I
Phase II
Bioreactor Performance-Phase II
(Effect of Empty Bed Contact Time (hrs))
ClO4- m g/L
Influent
30
140
120
100
80
60
40
20
0
0
Effluent
15
50
12
100
Days
8
150
Bioreactor Performance-Phase II
(Effect of Empty Bed Contact Time)
Average % ClO 4- removal
120
96
100
80
89
87
15
11
75
60
40
20
0
28
Empty Bed Contact Time (hrs)
7.5
Bioreactor Performance-Phase II
(Effect of sulfur size particles)
Average % ClO 4- removal
100
90
80
65
60
60
40
20
0
21
7.6
Empty bed contact time (hrs)
4
Bioreactor Performance-Phase II
100
14
12
10
8
6
4
2
0
80
60
40
20
0
0
5
10
15
20
25
Distance cm
Nitrate
Perchlorate
30
35
ClO4- m g/L
NO3-N mg/L
(Effect of Nitrate on Perchlorate
Removal)
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 mg/L)
were reduced to < 4 mg/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