Detroit Edison admitted in 1999 that Fermi 2's high-level radioactive waste storage pool could begin boiling in 4 hours, 12 minutes

NRC file photo of Fermi 2 on the Lake Erie shoreline near Monroe, MichiganOn Nov. 19, 1999, Detroit Edison admitted that its densely packed high-level radioactive waste storage pool at Fermi 2 -- the largest reactor in the entire world of the Fukushima Daiichi design (General Electric Boiling Water Reactor of the Mark 1 containment design) could begin boiling just 4 hours and 12 minutes after loss of electricity to run storage pool cooling system water circulation pumps. 

Detroit Edison admitted: “Complete loss of all forced pool cooling is not considered a credible event in the design basis, as stated in UFSAR [Updated Final Safety Analysis Report] section 9.1.3.3. Nevertheless, a loss-of-cooling event was analyzed for all discharge scenarios. The interruption of the cooling to the pool was assumed to occur coincident with the  SFP [Spent Fuel Poo] peak decay heat generation. The analysis determined the time when the pool bulk water reaches boiling and the resultant maximum water loss rate from the surface. The calculated time to boil is 4.20 hours after the cooling is lost in the most severe scenario. However, this is acceptable because the corresponding boil-off rate is less than the makeup capacity of 100 gpm [gallons per minute] available from the condensate storage tanks, and additional sources of makeup including the fire protection system and category I systems which can be aligned to supply SFP makeup. Additionally, the 4.20 hour period allows sufficient time for the operators to intervene and line up an alternate source to remove the decay heat and replenish the pool inventory.”

This excerpt can be found on Page 7 of “Enclosure 1 to NRC-99-0084,” ENCLOSURE 1 TO NRC-99-0084, FERMI 2, NRC DOCKET NO. 50-341, OPERATING LICENSE NO. NPF-43, REQUEST TO REVISE TECHNICAL SPECIFICATIONS: DESIGN FEATURES-FUEL STORAGE AND PROGRAMS AND MANUALS-HIGH DENSITY SPENT FUEL RACKS, DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGES, attached to AFFIDAVIT (of Michael P. McNamara of Holtec International) PURSUANT TO 10CFR2.790, dated Nov. 19, 1999, sent by Douglas R. Gipson, Senior Vice President, Nuclear Generation, Detroit Edison to NRC on Nov. 19, 1999.