APR: your source for nuclear news and analysis since April 16, 2010

Monday, March 14, 2011


The situation at Fukushima Daiichi nuclear power station is about a hair's breadth from being an assured Class 9 Reactor Accident. Let's give a Situation Report....

Since the situation is very complex, let's review some of the most relevant items with some insight just as bullet points:

-Officials are telling everyone between 20 and 30 KM to remain indoors, wash off clothing hanging outside or leave it out there, close windows, dust off all clothing. No ventilating equipment is to be used. This is fallout response, as in after a nuclear accident or attack. This is an admission that there is serious worry of serious release of fuel, fission fragments, or radioactive materials.

-Two plants have suffered hydrogen gas explosions from radiolytic hydrogen which has damaged their reactor buildings. This applies to No. 1 and No. 3 plants which are visibly damaged. Both plants likely have fuel element damage.

-One plant is experiencing a very serious and in fact grave situation with high radiation levels and an audible explosion sound in the area of its pressure suppression pool. This is No. 2 plant. TEPCO says that the fuel was exposed partially or fully for a long period of time, perhaps 140 minutes. This plant may be in a state of core melt and failure.

-Another plant, in a defuelled state or partially defuelled state, is experiencing a (conventional) fire apparently in its reactor building or in the area of its spent fuel facility. This is No. 4 plant.

The newly reported high rad levels at the site will greatly complicate all work at the very least by reducing stay times on site and especially at the failing plants, so that all the expertise on the site will have to cycle out as the personnel reach their exposure limits. Surely as here there will be local permission to extend rad exposure limits for key personnel but there's a ceiling beyond which they won't be allowed to go and fresh personnel, perhaps new to the situation in toto, will have to cycle in... although at TMI-2 this proved to be beneficial.

ATOMIC POWER REVIEW 10:55 PM Monday 3/14


  1. #2 had 140 minutes naked - and maybe my sleep deprived brain is wrong but I thought it had an at least equal time exposed earlier in the day.

    Thanks Will for your steady, unhysterical work on this.

  2. Yep- is this it? :

    "Japanese broadcaster NHK reported the pumps stopped flushing seawater into the reactor after running out of fuel when a plant official who was operating the pumps left his seat to monitor something else."


  3. Thank you, Fintan! Looks like the 140 minute time period may be time TOTALLY without cooling water supply, either in terms of flow to whatever water level was present in the bottom of the vessel or with any of whatever that was touching the fuel. The operators in the control room themselves may not even know.

    I am not surprised about the pump failure; I had been imagining today the stress these operators must be under, recalling my days on a Navy Sub as a reactor operator and thinking that at our worst we never got even close to this kind of nightmare.