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