Details Emerge About Failures at Fukushima
- Jul 7, 2018 12:17 am GMT
Interim Fukushima report lists lapses
27 Dec 2011 (NucNet): Japan’s response to the crisis at the Fukushima-Daiichi nuclear power plant was flawed by poor communication and delays in releasing data on dangerous radiation leaks at the facility, a government-appointed investigative committee has found.
A 507-page interim report released 12/26/11 attaches blame for the March 2011 nuclear accident and its consequences to Japan’s central government and administration, as well as the utility that operates the plant, Tokyo Electric Power Company (Tepco).
(Note to readers: See link at end to 22-page executive summary in English. Additional media coverage at links below.)
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The report says poor planning worsened the disaster response, noting that authorities had underestimated tsunami risks that followed the 9.0-magnitude earthquake.
The 15-meter-high tsunami that struck the plant was twice as high as the highest wave predicted by officials. The erroneous assumption that the plant’s cooling system continued to function after the tsunami struck worsened the disaster, the report says.
The report, whose final version is due to be completed next year, also found that plant workers had no clear instructions on how to respond to such a disaster, causing miscommunications, especially when the tsunami destroyed backup generators.
Workers failed to immediately look for alternative sources of water to cool the overheating reactors because they assumed the system was working, even though warning signs told them otherwise.
The report highlights a number of specific inefficiencies. It says unit 1 at Fukushima-Daiichi lost its all power supplies shortly after the tsunami and when its isolation condenser system (IC) failed “appropriate corrective action” was not taken nor instructions given.
Emergency response headquarters and Tepco head office in Tokyo knew about the IC failure, but maintained their view that the system was operating normally.
“These incidents in sequence indicate that not only the shift operators, but also the emergency response headquarters and Tepco head office did not fully understand the function of IC operation”.
The report says some decisions were made only among shift operators and a limited number of staff at emergency response headquarters. They did not ask for instructions from managers and reports from emergency response headquarters to plant managers were delayed. This was a direct cause of the delay of alternative water injection at unit 3.
The report also highlights failures in establishing and operating an emergency response center. Japanese law says that once a nuclear accident occurs, a local nuclear emergency response centre should be set up close to the accident site.
The center for Fukushima-Daiichi was about five km from the plant, but did not function as intended. It was evacuated for a number of reasons including loss of telecommunications, loss of power, shortages of food, water and fuel; and elevated radiation levels in the building which was not equipped with air cleaning filters.
In other words, says the report, the emergency center lost its functions because there was no allowance for a nuclear accident happening at the same time as an earthquake, and the building itself was not designed to withstand elevated radiation levels, despite being intended for use in nuclear emergencies.
Monitoring radiation levels in the environment should have been indispensable for preventing radiation exposure and planning evacuations, but the monitoring system was not sufficient because “many monitoring posts” were washed away by the tsunami or became inoperative because of power cuts.
The interim report confirms that of the six reactor units at Fukushima-Daiichi, units 1 to 3 were in operation when the earthquake struck and units 4 to 6 were in “maintenance mode”.
It says units 1 to 3 “appeared to have automatically scrammed”, but external power supplies and almost all in-house AC power supplies were lost because of the earthquake and tsunami.
Reactors and spent fuel pools lost their cooling capabilities and hydrogen explosions occurred at units 1, 3 and 4. The explosions “were presumably caused” by hydrogen released from possible core damage The unit 2 reactor core also seems to have been damaged, although the investigation is still incomplete, the report says.
The investigation committee also blames authorities for their “inappropriate preparation” of nuclear disaster recovery. In particular, it says the prefectural and national governments should “proactively involve themselves” with local governments of cities, towns, and villages for prevention and evacuation planning.
The English language executive summary of the report is online:
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