The New York Times reports that Tepco has announced a timeline for securing the wrecked Fukushima 1 nuclear power plant:
The first part of the plan would take about three months and include installing a cooling system to lower the temperature in the reactors and spent fuel pools, as well as reducing radiation in the surrounding area, said Tsunehisa Katsumata, the chairman of Tokyo Electric.
The second part, which would take an additional six months, would include more pumping of water, the introduction of a new heat removal system and reducing the amount of contaminated water. The wreckage from three of the four most severely damaged reactor buildings would then be removed and the reactors inside would be covered.
While this vague outline is the most concrete recovery plan to date, it is of course subject to what is physically possible. Intentions, even with an approximate time scale, do not in any way prove that the plan is workable.
Let us remember that on the weekend following the quake and tsunami, Tepco moved mobile diesel generators onto the reactor site hoping to restart the cooling pumps using mobile emergency power, but found that the power connections were incompatible and the electrical switches had been destroyed by sea water. That plan had to be abandoned.
Then Tepco installed a fresh external power line and a new switch panel to restart pumps with restored grid power, but no further progress has been made in getting the original cooling pumps going again. That plan has been quietly abandoned and Tepco is still using temporary electrical pumps that inject fresh water from a nearby dam. There is no closed circulation system in place. Unlike the purified fresh water normally used for cooling, the dam water can contain small amounts of calcium that can clog pipes and valves.
Tepco no longer seems to publish how much water is being injected per hour into the three units. It also seems to have stopped publishing radiation figures for the drywell and suppression chamber, perhaps to avoid questions about a sudden major spike of radiation in unit 1 after the April 7 quake.
No explanation is being given about what is happening to all the injected water, how much re-condenses from steam into the reactor drywell (primary containment) or suppression chamber or leaks in liquid form into these areas and how much may be leaking outside the reactor containment or is released as steam (the containments of unit 2 and 3 are at atmospheric pressure). The NRC suspects that the circulation pump seals at units 1 through 3 are damaged, allowing water to leak. Probably Tepco doesn’t tell us where the water goes because nobody (including Tepco) really has any data.
It’s easy to say it will take three months to install a new cooling system, but if even one of the units still leaks large amounts of water too radioactive to go near it, that’s going to be a tough plan to implement. It’s not enough to get water into the reactor and to cool water or steam coming out of the reactor with a heat exchanger, all of this also has to happen without massive leaks that continually carry out radioactivity from damaged fuel rods. Many more afterquakes expected in the region for the rest of the year, some of them at magnitude 7 and greater, will complicate the recovery.
The recovery plan for Fukushima 1 will remain an uphill struggle for many months to come.
- Tepco presentation (2011-04-18)
- Plan Set for Crippled Japanese Nuclear Plant (New York Times, 2011-04-17)