The government of Japan has approved a revised Tokyo Electric Power Company (Tepco) cleanup plan that delays the start of fuel rod removal from Units 1 and 2 at the crippled plant, but maintains a target of 2018 as the start for removal of stored Unit 3 spent fuel.
Removing stored fuel from the damaged Unit 3 building is on track for a start next year, ironically because the building is more heavily damaged than the other two reactor buildings, allowing easier access to the pool storing the fuel rod assemblies, according to a report in the Japan Times.
Removal from the Unit 3 pool is expected to be complete by the end of 2020, the year in which removal from Units 1 and 2 was expected to begin. It is now expected that removal from those two units will not start until 2023.
There are a total of 1,573 fuel rod stored in pools for units 1 through 3, which were all damaged in the March 2011 earthquake and tsunami event.
The plan approved Tuesday outlines a decommissioning process that is estimated to require about 30-40 years to complete, yet it is already being described as a hypothetical estimate in part because Japan does not have a long-range storage facility for spent nuclear fuel. As such, even the fuel that is retrieved from the storage pools will remain in site, prolonging the status of the site as not fully decommissioned.
The current plan focuses on fuel removal, part of which will require technology – robotic devices, essentially – that is in development. While a water-proof probe dubbed the "sunfish" found what appears to be melted fuel at the bottom of the Unit 3 core, radiation levels and in Units 1 and 2 have proven too high to allow for the remote controlled probes sent into those units to remain viable for long enough to locate the melted fuel in the reactor cores.
The plan also focuses on containment of contaminated water, which has plagued clean up efforts from the start. An underground barrier of frozen soil prevents some of the groundwater from flowing under and into the contaminated areas, as does a series of pumps established on higher ground near the plant that diverts groundwater out of the area. Together, the water diversion strategies have lowered the accumulation of contaminated water to 200 tons per day, about half of what it was previously. With continued work on diversion techniques, the new target is to lower accumulation to 150 tons of water per day that must be treated and stored.A total of 800,000 tons of contaminated water has accumulated on site. It is being treated, but still contains tritium, a radioactive isotope difficult to remove. However, the plan to dump this water into the Pacific Ocean has been met with resistance from local fisherman. On the other hand, the hundreds of storage units holding all that water is taking up a concerning amount of space at the facility, which sometimes interferes with other cleanup activities.
Anonymous comments will be moderated. Join for free and post now!