Reading Fukushima Status Reports

Now that things are happening less rapidly at Fukushima, I’ve been looking less frequently at the status reports. It became obvious early on that the more general aftermath of the earthquake, the loss of electrical power and communication, and other factors were leading to erroneous reports and too much instant interpretation. Taking some time helps to sort out the erroneous reports, but conflicting reports and interpretations still exist.

Several sources are making status reports available. The basic reports come from Tepco, the Tokyo Electric Power Company, which owns the Fukushima generating plant. The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office is also issuing updates which are based on the Tepco reports and other information. They are not directly accessible via the Web, but Jeffrey Lewis is posting them regularly at Arms Control Wonk. The Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) is making their radiation readings available in English here.

What do today’s status reports tell us?

From Tepco’s “Status of TEPCO's Facilities and its services after Tohoku-Taiheiyou-Oki Earthquake(as of 5:00PM March 23)”, all four of the Fukushima Daini reactors are in cold shutdown. There has been some concern about their condition, but it has not been as serious as at Fukushima Daiichi. It’s reasonable to expect they’ll remain in cold shutdown.

The latest Daiichi report (as of 11:00 PM Mar 22nd) says that two workers were injured while setting up a temporary power panel. These injuries are most likely industrial injuries, rather than radiological ones.

A concrete pumping truck is now being used to pump cooling water. This appears to be both to the spent fuel pools, which are located high in the reactor buildings, and also over the concrete containment structures, which is an indirect, but apparently effective, way of cooling the reactor cores when water cannot be injected directly into the containment.

The puffs of smoke that have caused temporary evacuations of the control rooms have not been accompanied by increases in radiation. A gray or black color could indicate a fire, while white “smoke” is more likely steam.

From the FEPC reports, the spent fuel pools at Units 2, 5, and 6 are at acceptable temperatures. Water is being added to the pools at Units 3 and 4, but no temperature is given. The reactor cores in Units 1, 2, and 3 remain partially uncovered by water, but the fact that their containment is holding pressure suggests that there are no large breaches.

The estimates for the height of the tsunami at Fukushima keep going up. Today’s is 14 meters.

I’ve wanted to look at the radiation readings in detail and haven’t had a chance to so far. Maybe I will do that next. The radioisotopes that I have seen reported are those that would be in the reactor cores rather than the spent fuel pools. Iodine-131 has a half-life of eight days, which means that it is down to insignificant levels after about three months and would be in the reactor core, but not in the pools. We know that steam has been vented from the reactors, so it appears that the radiation being seen is from this venting, or possibly from breaches of containment.

If there had been fires in the spent fuel pools, additional radionuclides would have been detected.

I am reserving judgement on reports like this. If it is true, we will find out in the investigations that will follow. But it doesn’t tell us anything useful about the current situation.

[Cross-posted at BMJ Blogs.]