Update # 42B: August 3, 2011
by Nelle Maxey
More international press and internet blog sites reactions to the very important story of the high radioactivity levels reported from the Fukushima plant.
TEPCO continues to attempt to downplay this, but nuclear experts are speaking up in the press.
It is particularly important to understand a point made in the Bloomberg article that the contaminated water in the reactor basements is mitigating the radioactivity levels from the melted through reactor fuel. Once the water is removed by the decontamination/recirculation system, radioactivity levels will increase.
Also the 10 Sv/hr reported in much of the press should actually be reported as "unmeasured amounts of radiation higher than 10 Sv/hr" since the equipment being used for measuring only measured to a maximum of 10 Sv/hr. The Ashai article also makes the point that radiation levels are probably even higher inside the exhaust pipe since this was an external measurement only.
The Daily Yomiuri article has a simple illustration showing the connection between the location of the reading and the main exhaust stack.
Here is the Bloomberg story with relevant quotes (read full story at link).
"It's probably the first of many more to come," said Michael Friedlander, who spent 13 years operating nuclear power plants […]
"If nuclear fuels melted through containment chambers, Tepco will find even higher radiation readings after water in building basements is removed," said Tetsuo Ito, the head of the Atomic Energy Research Institute at Kinki University. […]
Here is the Daily Yomiuri Online story with relevant quotes (read full story at link):
"[…] The fact that such high levels of radiation [at least 10 sieverts per hour] were detected near piping connected to the outer atmosphere is further evidence that radioactive materials have spewed from the crippled reactors at much higher levels than previously believed. […]
Because that level of radiation was detected on the outside of the piping, the level inside the piping could be even higher. […]
TEPCO officials had assumed that high levels of radiation would mainly be detected within the reactor buildings containing the cores where the meltdowns occurred. […]"
And the Ashai story with an interesting diagram (although I haven't yet found a source for the speculation that there is contaminated water in the pipe).
The Physics Forum has some very interesting information and comments concerning the readings in the latest threads, Thread 672 and Thread 673.
Here are some quotes I've pulled from the threads which connect some of the dots:
"Should this be a surprise? When there are three cores worth of material getting leached for months, one would expect every surface in the facility to be dripping with redeposited cesium, especially the venting paths. What it says to me is that there is no rational way forward other than to drain the water and then bury the facility.
It surely would be irresponsible to have people risk their lives to dismantle a massive site just to rebury the debris elsewhere. Plus the burial need only last for a thousand years or so. By then, the cesium will have decayed."
"The robot found more than 5000 mSv/hour in a room on unit 1 reactor building 2nd floor. The 10,000 mSv/hour pipe mentioned yesterday runs across that room."
"Christoph Mueller of tec-sim.de writes (translated from the German original [by blog poster]):
1) Clarification about the high radiation figures in the pipe elbow. It is a typical phenomenon that tiny particles in a gas flow deposit at an elbow, as they have difficulties, flowing "around the corner". They fly straight on and hit the wall and remain stuck there. Therefore highly radioactive deposits form at elbows. This has nothing to do with rain or other effects, as some "experts" theorize in the press today. In all elbows, through which radioactively polluted gases flowed in a controlled venting such deposits can be found. It is only a matter of time when they are detected.
2) Clarification about the contaminated rooms in unit 1. Since at the point of controlled venting of the containments the containment atmosphere was highly contaminated because of the melt-down, a large portion of the radioactivity will have condensed in the filters, which because of that will radiate strongly. That's exactly what TEPCO has now found while inspecting the filter room in unit 1."
"The normal venting path uses filters/charcoal scrubbers, but the hardened venting system added in the 1990s (based on modifications installed in US reactors after TMI-2) uses an unfiltered vent path."
"…the operators got permission to release contaminants directly to the environment during emergencies instead of having to spend money on replacing their existing, severely undersized filters and scrubbers."
"A new independently acquired JNN video taken last week. The car passes close to the 10000 mSv/hour pipe. Then workers are shown being busy with hoses outside the water treatment facility. Their geiger counter reaches 4 mSv/hour as they are driving seaside close to unit 4 turbine building. This is higher than the 2.2 – 2.5 mSv values written on Tepco survey maps."