6 years ago
This goes to show just how bad the situation is – no, not the situation with the reactors (which is bad enough), but the situation with the flow of good information.
It had previously been reported that there was a fire in the Spent Fuel Pool of the Unit 4 nuclear reactor. However, it wasn’t quite what it seemed.
Tokyo Electric Power Co. said that an oil leak in a cooling water pump at Unit 4 was the cause of a fire that burned for approximately 140 minutes. The fire was not in the spent fuel pool, as reported by several media outlets. Unit 4 was in a 105 – day – long maintenance outage at the time of the earthquake and there is no fuel in the reactor.
Or was it all it seemed to be?
Near the plant entrance, which is somewhat removed from the building, radiation rose to 11.93 millisieverts per hour at 9 a.m. but was back down to 0.5964 millisieverts at 3:30 p.m.
Elevated radiation levels were also detected in northern Kanto and the greater Tokyo area, which is further south. Readings from 9 a.m. to 5 p.m. averaged 10 times higher than normal in some places, but still far below any level that would have an effect on the human body.
The No. 4 reactor had been shut down for a routine inspection, but the water temperature in the pool used to store spent fuel rods was rising. With the power now out and crews unable to enter the building, there is no way to know what is happening in the pool. If the temperature continues to rise, the rods could melt, threatening to release huge amounts of radioactive material.
From having performed the spent fuel characterization and shielding calculations, I know that the dose rate in a fuel pool building with the fuel uncovered by water would be as high as 50,000 rads/hr or even higher depending upon specific assumptions such as fuel burnup, decay time, enrichment, etc. That’s why most U.S. reactors have multiple (not just redundant, but multiple) means of makeup of borated water to the Spent Fuel Pool.
So the operators cannot get into the building to observe the conditions due to lack of habitability. If this fire is consuming oil, that’s one thing. If there is a Zirconium (cladding) fire due to loss of water over the fuel assemblies, then given the lack of a hard containment for the spent fuel building, I am actually more concerned about that than releases of radioactivity from the reactor buildings due to holdup, decay, sedimentation and plateout of fission products inside containment.
But the point is that there is still a dearth of good, high quality, technical information flowing our direction. Foxnews reported this morning that the dose (rate – although they didn’t understand that dose [rate] has units of time and didn’t report it as such) from radiation from the plant was the same immediately surrounding the plant and at 18 miles from the plant. Of course, this is physically impossible given that radiation decreases like sound and light with the inverse of the square of the distance from the source (1/R²).
Be careful what you read – and believe.
UPDATE #1: Or it could all have been steam from pool boiling.