Criticality Analysis of the Cask Drop Accident

Conference · Sun Jun 04 00:00:00 EDT 1989 · Transactions of the American Nuclear Society

OSTI ID:5237255

The accidental drop of a 100-t light water reactor spent-fuel shipping or storage cask in a spent-fuel pool can lead to severe distortion of the spent-fuel racks and stored assemblies. This is a serious challenge to the criticality safety margins designed into the storage racks. Under such conditions, credit is allowed for the presence of soluble boron, but analysis of the geometric distortion must be included. The objective of this paper is to demonstrate the criticality safety of a typical pressurized water reactor (PWR) spent-fuel rack for the cask drop accident. In this typical rack, the storage cell is a steel canister surrounded by boral sheets held in place by an outer steel wrapper. Criticality control is by flux trap between cells. The nominal center-to-center spacing, lattice pin pitch and flux trap gap are 10.25, 0.58, and 0.694 in., respectively. Since the cask drop accident involves unpredictable distortions in geometry, conservative assumptions about the final geometry are made in order to bound the reactivity effects. These assumptions include collapsed flux trap and variation of lattice pin pitch. Criticality analysis of the ask drop accident was performed with CASMO-3 and KENO-Va. If credit is taken for the presence of soluble boron in spent-fuel pool water, the K_eff of the spent fuel racks will be below 0.95 for the cask drop accident. However, this conclusion is rack type, fuel type, and soluble boron level dependent. If no soluble boron is present, a criticality hazard might exist.

• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• OSTI ID: 5237255
• Report Number(s): CONF-890604-; CODEN: TANSA; TRN: 90-002660
• Journal Information: Transactions of the American Nuclear Society, Vol. 59; Conference: Annual Meeting of the American Nuclear Society, Atlanta, GA (United States), 4-8 Jun 1989; ISSN 0003-018X
• Publisher: American Nuclear Society
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BWR TYPE REACTORS
SPENT FUEL STORAGE
CRITICALITY
CONTROL
PWR TYPE REACTORS
ACCIDENTS
BORON
C CODES
FUEL ASSEMBLIES
FUEL POOLS
FUEL RACKS
K CODES
MULTIPLICATION FACTORS
REACTIVITY
REACTOR LATTICES
SPACE DEPENDENCE
SPENT FUEL CASKS
SPENT FUEL ELEMENTS
US NRC
CASKS
COMPUTER CODES
CONTAINERS
ELEMENTS
FUEL ELEMENTS
MECHANICAL STRUCTURES
NATIONAL ORGANIZATIONS
REACTOR COMPONENTS
REACTORS
SEMIMETALS
STORAGE
SUPPORTS
US ORGANIZATIONS
WATER COOLED REACTORS
WATER MODERATED REACTORS
Nuclear Criticality Safety Program (NCSP)
Accidental Drop
Water Reactor
Spent-Fuel Shipping
Storage Cask
Severe Distortion
420203* - Engineering- Handling Equipment & Procedures
420204 - Engineering- Shipping Containers
210100 - Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
210200 - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled