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from NUKE INFO TOKYO 74 (Nov./Dec 1999)

-- A Nuclear Power Plant Shutdown due to a Power Failure
-- Worker Compensation Payments Approved for Nuclear Plant Workers
-- Effects of Radiation Other Than Cancers
-- JCO Accident Further Delays Japan's Nuclear Power Plan

A Nuclear Power Plant Shutdown due to a Power Failure

Power supply was off in a wide area in Kyoto Prefecture on October 27. It was caused by a trouble at a substation, and about 420,000 households were affected and trains and subways were held up. Owing to the power stoppage Takahama 1, 3 and 4 (PWRs and a total output of 2,566 MW) in Fukui Prefecture were automatically shut down, as power supply was cut off. Takahama 2 (PWR, 826 MW) had been suspended for a regular inspection.

The power was mostly restored in 25 minutes. It was, however, three or four days later that the reactors resumed operation, from 30th to 31st one after another.

This trouble clearly revealed the weakness of nuclear power plants as a power supply source. Since reactors are attended with enormous danger, they are very carefully protected in a way that they will stop operation even with a slight anomaly in the transmission system. In other words they easily shutdown automatically, and once they are shut down, it takes time to resume operation. At the time of the recent automatic shutdown of the three reactors, steam was mixed in the lubricating oil of the bearings of the turbines and feed pumps, and it took a few days to change the lubricating oil. Even without it, it takes one day to resume operation.

After the power was restored, power supply was done with hydraulic and thermal power stations.

For reference the three reactors were shutdown all at once in 1991 due to a power failure. It was caused by a stoppage of power supply for a second due to a lightening on the power line. It took one to two days for the reactors resuming operation.

Worker Compensation Payments Approved for Nuclear Plant Workers

A 54-year old male worker under an in-house subcontracting working for nuclear plants was approved of worker compensation payments as recognized his lymphocytic leukemia as it was caused by work-related radiation. He had been engaged in inspection of equipment at nuclear plants at various parts of Japan for more than 12 years from December 1984 to January 1997. He was exposed to more than 0.6 sievert of radiation. He became ill in September 1998, and applied for worker compensation payments in January 1999.

There have been merely four cases in Japan that nuclear plant workers were approved of their applications for worker compensation payments, as even when they become ill, it is difficult to prove the causal relationship between the illness and radiation they suffered from working at nuclear-related workplaces. There are many illnesses caused by radiation (see separate article), but only leukemia is recognized as work-related illness for compensation. It is also only for people whose radiation dosage is very high.

Meanwhile, the application for worker compensation payments were approved, on October 26, for the three workers exposed to radiation during the criticality accident at JCO. As these workers are suffering from acute radiation poisoning, whose causal relationship is very clear, their application was approved in six days after filing. This is the first case that worker compensation payment was approved for an acute radiation sickness.

Effects of Radiation Other Than Cancers

The causal relationship between the effects of radiation exposure and cancer has been proved, and recently data showing the effect of radiation exposure to other illnesses have been compiled. It was published in the recent issue of Radiation Research (italicize), a U.S. journal, by Yukiko Shimizu, Deputy Director of Epidemiology and others at the Radiation Effects Research Foundation.

They studied about 2,700 people, out of the atomic bomb victims in Hiroshima and Nagasaki who had died between 1950 and 1990, who died of other illnesses than cancer. They found that the more high radiation dosage the victims received, the higher the rate of deaths from heart diseases, cerebral apoplexy and liver troubles.

RERF directors are taking a cautious stance, claiming that the casual relationship between radiation exposure and heart diseases has not been proved by examinations on animals, thus further studies being required. The director of epidemiology, however, recognized that the increase of the death rate cannot be explained by the reason other than radiation exposure.

JCO Accident Further Delays Japan's Nuclear Power Plan

The additional reactor construction plans tended to be delayed even before the JCO accident occurred, but the accident seems to further delay them. Essentially, though, the greater reason is on the side of electric companies, that they cannot expect much power demand increase. In addition, local governments are not so enthusiastic about additional reactors, as the nuclear plant construction has not brought as much effect as they expected for local economic promotion.

The Japan Atomic Power Co. on October 27, submitted a report on Tsuruga 2 which had had an accident of an enormous amount of cooling water leakage (see NIT Nos. 72 and 73) to Fukui Prefecture. In the report they compiled their finding of the investigation of the causes and measures to prevent recurrence. JAPCO also submitted a plan to resume the operation in late January 2000. To this, the Prefecture only stated that they would want to take a cautious response.

JAPCO cannot propose their plan to build 3 and 4 reactors unless Tsuruga 2 resumes operation. They are also unable to obtain agreements with local municipalities for starting safety inspection for an improved measure for FBR Monju.

The Japan Nuclear Cycle Development Institute was scheduled to propose to Ibaraki Prefecture and Tokaimura, on October 1, to resume operation of Tokai Reprocessing Plant. This plan was naturally shelved. Unless the operation of the reprocessing plant is resumed, ATR Fugen will lose the destination of delivery of spent fuel, and it is likely that Fugen has to be suspended its operation.

The delay of the start of use of MOX fuel at Takahama 4, which was scheduled in October, is inevitable. It was decided to remanufacture the fuel for reactor 3 (See pp.5-6). With regard to the use of MOX fuel at Kashiwazaki 3, the mayor of Kashiwazaki City proposed to postpone it, and the director of power plan also indicated the postponement. The Kyushu Electric Power Co. was planning to propose Saga Prefecture and Genkai-cho the use of MOX fuel at Genkai 3, but the company decided to go back to the drawing board.




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