(Updates with professor’s comments from fifth paragraph.)
June 8 (Bloomberg) -- Japan plans a “fundamental revision” of its nuclear safety rules and will create an independent regulator to prevent a repeat of the disaster at the Fukushima Dai-Ichi atomic power station.
A report by the government last night also said a national debate is needed on the “whole concept of nuclear power generation,” indicating an energy policy that powered Japan after World War II into the ranks of the world’s leading economies is being questioned.
The current regulator, the Nuclear and Industry Safety Agency, has been criticized for not ensuring that Tokyo Electric Power Co. heeded earlier warnings that a tsunami could overwhelm the Fukushima plant. NISA reports to the ministry that promotes nuclear power, which hampered quick responses to the disaster, the government said in the report to be submitted to the International Atomic Energy Agency.
“We will first separate NISA” from the Ministry of Economy, Trade and Industry, Minister Banri Kaieda said at a news briefing in Tokyo yesterday. “Radiation monitoring is handled by the science ministry, and there is also the Nuclear Safety Commission under the cabinet office, so we will consider how we can unify these.”
The Fukushima nuclear station suffered three reactor meltdowns after an earthquake and tsunami on March 11 knocked out power and backup generators, crippling its cooling systems. The disaster displaced 50,000 households in the evacuation zone because of radiation leaks into the air, soil and sea.
“Creating an independent nuclear agency is a good thing, but it’s not clear what should be expected from it,” said Hironobu Unesaki, a nuclear engineering professor at Kyoto University. Japan needs a credible and transparent system for releasing accident information and radiation data, he said by telephone today.
It was “irresponsible” of Tokyo Electric and NISA to release inaccurate data after the accident, and differences in the Japanese and U.S. officials’ assessment of the crisis led tensions between the two countries and prompted the U.S. to advise its citizens living within 50-kilometers of the plant to evacuate, Unesaki said.
The Japanese government recommended a 20-kilometer evacuation zone around the stricken nuclear reactors and advised people within 30 kilometers were advised to stay indoors.
“Information wasn’t properly disclosed,” Unesaki said. “Proper disclosure and transparency will lead to trust.”
Investors have dumped Tokyo Electric shares at a record pace amid bankruptcy speculation, driving the stock down 90 percent since the accident and erasing about 3.1 trillion yen ($39 billion) in value. The stock today slid 7.4 percent to 200 yen, the lowest since at least 1974, as of 2:36 p.m. on the Tokyo Stock Exchange.
Two nuclear emergency response systems failed because information from Dai-Ichi “could not be obtained,” yesterday’s report said without explaining further.
The Emergency Response Support System, which monitors reactors after an accident and forecasts progress, and a system to measure atmospheric concentrations of radioactive materials, known as The System for Prediction of Environmental Emergency Dose Information, didn’t function, it said.
The report confirmed the likelihood that fuel rods melted in pressure vessels of reactors No. 1, 2 and 3 and fell to the bottom of the containment chambers. The pressurized vessels of the reactors, which contained the rods, were likely damaged and a “considerable” amount of fuel leaked to the floor of the outer containment vessel, it said.
The utility known as Tepco has pumped millions of liters of water to cool the three damaged reactors and much of that has overflowed into basements of buildings. The amount of contaminated water rose to about 105 million liters (28 million gallons) from 100 million liters on May 18, Tepco said June 3.
A total of 55,400 metric tons (55.4 million liters) of water was poured into the No. 1, 2 and 3 reactors, of which about 34,100 tons of radiated water was estimated to have leaked from the reactor pressure vessels, according to the report, which cited Tepco data as of May 31.
Many workers at the Fukushima plant were without personal dosimeters to measure radiation exposure for weeks after the earthquake because the tsunami soaked their devices in seawater, making them unusable.
The shortage forced groups of workers to depend on single devices, the government said in the report. All workers had been reissued personal dosimeters as of April 1, the report said, indicating many had been working in radioactive areas without the devices for about 20 days.
As of May 23, 7,800 workers had entered the plant and were found to have been exposed on average to 7.7 millisieverts of radiation, with 30 workers receiving exposure doses exceeding 100 millisieverts, the report said. The government increased the limit for workers engaged in radiation work to 250 millisieverts from 100 millisieverts to deal with the disaster. Some of the Fukushima workers may exceed 250 millisieverts in the future, the report said.
The dose limit is 500 millisieverts for workers in emergency rescue operations, according to the 1990 recommendation by the International Commission on Radiological Protection, the report said.
No harmful health effects were found in 195,345 residents living in the vicinity of the plant who were screened as of May 31. All the 1,080 children tested for thyroid gland exposure showed results within safe limits, according to the report.
--With assistance from ????, Tsuyoshi Inajima and Hidekiyo Sakihama in Tokyo. Editors: Alex Devine, Amit Prakash
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