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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
2
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 Recovery
Remove 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 Storage
Design 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
3
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
4
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) Canisters
Al or SS Construction
~4m (14’) Long, 0.33m(~14”) Diameter
J-Tube Vented
Z-Can (#Z13) with Fuel Pieces
OS Aluminum Canister
5
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
6
SRS Underwater Resin Deionizer Design
Background
Oversize (OS) Cans Contained Fuel Pieces
Oversize (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 System
28 liters CG8-H resin (strong acid cation resin)
100 m Filter - Sintered Stainless Steel Metal Filter
2 Independent Air Motors with Remote Operation Using Building Air Supply
Attach/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
7
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
8
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
9
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 FEC
A1 29 mR/hr 1 mR/hr 1 hour 1 FEC
A2 410 mR/hr 2 mR/hr 1.5 hours 1 FEC
A6 323 mR/hr 4 mR/hr 1.5 hours 2 FECs
A7 290 mR/hr 2 mR/hr 2 hours 2 ‘Z’ cans
1 4” can
A5 2.4 R/hr 10 mR/hr 3 hours 4 ‘Z’ cans
100 R = 1 Gy
10
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
12
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
13
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
14
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