Damaged Fuel Storage and Recovery A Case Study

Natraj C. IyerSavannah River National Laboratory

June 2, 2010

May 31,- June 4, 2010, IAEA, Vienna, Austria

Co-Authors: D.L. Fisher, R.L. Thomas, J.E. Thomas, T.J. SpiekerInternational Conference for Management of Spent Fuel from Nuclear Power Reactors

Ion exchange column Gear pumps

Check valves

Flow meter

Filter

Fuel storage can

System conforms to ASME Piping and Pressure Vessel Codes

Inlet

Outlet

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OutlineDamaged Fuel Storage in Isolation Canisters Called “Oversize (OS) Canisters”

Contents - Early Test Reactor Fuel Pieces and Damaged Fuel

Fuel Direct-Stored or In Other Cans within the OS Canisters

Special Underwater Filter/Deionizer for Damaged Fuel RecoveryRemove Cesium from High Activity Water (up to 5.8E6 Bq/ml in 3800 liters) from Six OS Canisters (No Release Into General Basin Water)

Special Design Apparatus for Underwater Remote Operation

Operation Results

OS Canister for L-Basin Damaged Fuel StorageDesign Features

Damaged Fuel Management at the Savannah River Site:- System to Store Damaged Fuel Underwater, Isolating It from General Basin;- System to Remove Water Activity from Oversize Canisters

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Spent Fuel Storage ExperienceStorage of MTR and non-MTR Spent Fuels

Stainless Steel, Zircaloy and Aluminum Clad Research Reactor Fuel

Aluminum Clad – Depleted Uranium Targets

Fuel Core (Meat): Depleted U, U- Aluminide, U-Sr Hydride, U- Silicide, U-Mo, UO2

Enrichment: 20 to 93%

Variety of SNF in Basin Storage

Storage of Variety of Spent Fuels for >40+ Years Primary Basin Storage Facility in U.S. for DOE Spent Fuel

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Damaged Fuel Storage Configuration in OS Canisters

Fuel Pieces and Damaged Fuel Storage

Tubes, tube sections, and pins

For Example - Fuel irradiated in the site Heavy Water Components Test Reactor and site production reactors: 1957-1963

Cladding: Zircaloy, Aluminum

Fuel Core: Umetal, UO2 U-Zr, U-Al, U-Mo, U-Fe

Place pieces in cans (Z-cans, B-cans)

Oversize (OS) CanistersAl or SS Construction

~4m (14’) Long, 0.33m(~14”) Diameter

J-Tube Vented

Z-Can (#Z13) with Fuel Pieces

OS Aluminum Canister

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Deinventory of Receiving Basin for Offsite Fuel

Savannah River Site

RBOF RBOF BuildingBuilding

L-BASIN BuildingL-BASIN Building

Goal: RBOF De-Inventory by September 2006 – Completed September 2003• Completed MTR transfer March 2001

~3800 Assemblies transferred starting 2-27-97Transfer goal was July 2001

• Completed 1st Non-MTR transfer March 2001• De-inventory shipments included SFO, EBR-II (Oct-00), TRR (Feb-98), Mk-42 (Oct-00), Mk-31

• Completed OS Canister recovery and transfer September 2003

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SRS Underwater Resin Deionizer Design

BackgroundOversize (OS) Cans Contained Fuel PiecesOversize (OS) Cans had High Activity Levels (5.8x106 Bq/ml) from Cs-137 Need to Open OS Cans to Re-Pack Fuel Without Releasing High Activity to Basin

Underwater System Designed and Built to Provide Deionization of OS Cans

Portable, Skid-Mounted System28 liters CG8-H resin (strong acid cation resin)100 m Filter - Sintered Stainless Steel Metal Filter2 Independent Air Motors with Remote Operation Using Building Air SupplyAttach/Detach Lines with Typical Basin Handling Tools

Resin Can in Shroud

Filter

Air Motor

Pump

Flow Meter

Discharge Port

Inlet Port

Hose to resin column

Discharge

Inlet

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Operation to Flush Oversize (OS) Cans

Inlet at Bottom of Can to Avoid Plugging by Debris in the OS Can

Opened Flanged Connection on the OS Can

Inlet Water from Basin

Outlet Water to Basin

Run for 1 Hour at 12 L/m

Ion exchange column Gear pumps

Check valves

Flow meter

Filter

Fuel storage can

System conforms to ASME Piping and Pressure Vessel Codes

Inlet

Outlet

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OS Flushing – Results

‘‘Red-lineRed-line’’

Underwater Deionizer in RBOF

Air Motor Remote Controls

OS Can

RO7 Meter to RecordResin Column Activityat “Red Line” Underwater

• Water Activity Initial (OS Can A3): 120,000 Bq/ml

• Water Activity Final (OS Can A3): 1,700 Bq/ml after 1 hour single-pass flushing at 12 lpm through 3800 liter OS Can volume

Performance Example

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OS Flushing – Results

Flushed A3, A1, A2, A6, A7 and A5 Cans

Can Number RO7 Initial Reading

RO7 Final Reading

Duration of Flush

Contents

A3 14 mR/hr 1 mR/hr 1 hour 1 FECA1 29 mR/hr 1 mR/hr 1 hour 1 FECA2 410 mR/hr 2 mR/hr 1.5 hours 1 FECA6 323 mR/hr 4 mR/hr 1.5 hours 2 FECsA7 290 mR/hr 2 mR/hr 2 hours 2 ‘Z’ cans

1 4” canA5 2.4 R/hr 10 mR/hr 3 hours 4 ‘Z’ cans

100 R = 1 Gy

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OS Flushing – Results6 OS cans flushed

internal cans containing pieces/failed tubes (vented)

primarily Zr cladding

fuel age: 1958/62 irradiation

319 Ci Cs-137 captured

1 cu. Ft CG8-H resin

1 month total operation

Findings

3 ruptured Z-cans

36 lbs. Oxide at bottom of 1 OS can

12 lbs. fines dispersed thru filter

6300 R/hr at red line final exposure rate

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Failed ‘Z’ and ‘B’ Cans Within OS Canisters

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Damaged Fuel Transferred to L-Basin

Fuel with Through-Clad Breaches May be Acceptable for Continued Direct Basin Storage

Evaluate Cs Release with Sip Test

Evaluate Expected Continued Release Based on Corrosion Model

Evaluate Capacity of Basin Deionization System

Damaged Fuel in Cans Placed in New OS Canisters

Oversize (OS) Canisters for L-Basin

L-Basin OS Canister Rack

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OS Canister Improved Design and L-Basin Storage

OS Canister with Improved J-tube

Isolates Enables Gas Release

Fuel Direct-Stored or In Cans within OS Canisters

13 New OS Canisters Stored in L-Basin for Damaged Fuel

1 New OS Canister for Resin Column

Latest J-tube Design on OS Canister

FEC loading

Lid installation

FEC loading

Lid installation

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Summary

Savannah River Site Experience in Underwater Storage of Severely Damaged Fuel Successful in Storage/Recovery/Repack Campaign

Fuel Recovery from OS Cans Used Special Design Underwater Deionizer

Damaged Fuel Management at the Savannah River Site:

-System to Store Damaged Fuel Underwater: Vented Canister Storage with Isolation of Canister Water from General Basin Water;

- System to Remove Water Activity from Oversize Canisters