Accession Number DE2012-1045845
Title MELCOR Model of the Spent Fuel Pool of Fukushima Dai-ichi Unit 4.
Publication Date 2012
Media Count 2p
Personal Author J. J. Carbajo
Abstract Unit 4 of the Fukushima Dai-ichi Nuclear Power Plant suffered a hydrogen explosion at 6:00 am on March 15, 2011, exactly 3.64 days after the earthquake hit the plant and the off-site power was lost. The earthquake occurred on March 11 at 2:47 pm. Since the reactor of this Unit 4 was defueled on November 29, 2010, and all its fuel was stored in the spent fuel pool (SFP4), it was first believed that the explosion was caused by hydrogen generated by the spent fuel, in particular, by the recently discharged core. The hypothetical scenario was as follows: power was lost, cooling to the SFP4 water was lost, pool water heated/boiled, water level decreased, fuel was uncovered, hot Zircaloy (Zr) reacted with steam, hydrogen was generated and accumulated above the pool, and the explosion occurred. Recent analyses of the radioisotopes present in the water of the SFP4 and underwater video indicated that this scenario did not occur. The spent fuel in this pool was never uncovered nor damaged. The hydrogen causing the explosion was apparently generated in Unit 3 and transported through exhaust ducts that shared the same chimney with Unit 4.
Keywords Accident management
Alloys
Aluminium
Boiling
Dimensions
Earthquakes
Explosives
Fuel assemblies
Fuel racks
Hydrogen
Nuclear power plants
Oxidation
Oxygen
Radioisotopes
Reactor accidents
Spent fuels
Stainless steels
Steam
Zircaloy

 
Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 77I - Reactor Fuels & Fuel Processing
77H - Reactor Engineering & Nuclear Power Plants
Corporate Author Oak Ridge National Lab., TN.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1226
Contract Number DE-AC05-00OR22725

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