There is yet another surprise at the Fukushima Daiichi nuclear power plant complex.
The long awaited arrival of electrical power to Tokyo Electric Power Company's devastated Fukushima Daiichi nuclear power station has yet another vital task to perform: restore cooling to an independent large scale common nuclear waste storage pond for all six nuclear units that has received no attention since loss of electricity following the earthquake and tsunami of March 11, 2011.
According to Yomiuri Shimbun news service (March 18, 2011), the giant common "spent" fuel storage pond has also been without cooling since the tsunami. The pool is not in a rated containment structure which is a concern if hydrogen gas generation leads to another explosion. The shared nuclear waste fuel assembly pool building is about 50 meters (150 feet) west of the now extremely radioactive Daiichi Unit 4. The common fuel pool facility has a total capacity of 6,800 highly irradiated fuel assemblies. According to TEPCO documentation from November 2010, the storage pool was at 90% capacity in March 2010 with 6,291 nuclear waste assemblies.
The large scale pool measures approximately 38 feet wide, 92 feet long and 35 feet deep. The older and highly radioactive nuclear waste assemblies allowed to cool down for many years in the six reactors' roof top storage ponds began its transfer to storage in the pool in 1997. From this pool, some of the fuel has been loaded into more secure dry cask storage units awaiting shipment to the Rokkasho nuclear waste reprocessing facility.
According to Yomiuri Shimbun, TEPCO authoriities have not been able to approach the largest nuclear waste storage facility at the complex because of high radiation levels emitting from Units 3 and 4. As a result, it was reported that TEPCO has not been able to check the giant cooling pond's temperature and water level. However, TEPCO officials reassure that this nuclear waste inventory also stored outside of a containment facility consists of the "coolest" assemblies in wet storage onsite.
However, even after two decades, a single used fuel assembly from a typical Boiling Water Reactor will emit over 3,000 BTU/hr.