Extension of Time Allowed Between Periodic Inspections of Reactors Nuke Info Tokyo No. 122

From April 2008, the time permitted before reactors are shut down for periodic inspections will be extended (long-cycle operation). Under the Electricity Utility Law regulations as they now stand, the maximum time allowed between the end of one periodic inspection and the commencement of the next is 13 months. However, from April there will be three categories, determined on the basis of an assessment of the performance of each plant. Depending on the category, the maximum time will be 13 months, 18 months or 24 months.

Cartoon by Shojji Takagi

It is claimed that categorization will be carried out cautiously. At first all plants will be allocated to the 13-month category and only gradually progress to the 18-month and 24-month categories. Also, even if a plant is assessed worthy of the 24-month category, it will not be able to advance there immediately without first progressing through the 18-month category. It will only be able to advance to the 24-month category after establishing a record of satisfactory performance in the 18-month category.

That said, the assumption is that the next generation plants currently being developed will all run for 24 months between inspections and probably the aim of the Nuclear and Industrial Safety Agency (NISA) and the utilities is to eventually allow all plants to operate for 24 months between inspections.

Since Autumn 2007, meetings have been held in regions which host nuclear power plants to explain the system to the regional and local governments and to the general public. However, at all these meetings there have been opposing voices and expressions of mistrust towards NISA’s one-way explanations, the purpose of which was to enable NISA to claim that it had obtained stakeholder understanding before imposing the new system. Naturally, everyone is skeptical after the fatal Mihama-3 accident (2004, NIT 102), the discovery of numerous cover-ups and instances of data manipulation (2007, NIT 117), and the problems at the Kashiwazaki-Kariwa nuclear power plant resulting from the Chuetsu-Oki Earthquake (2007, NIT 119). They wonder why now of all times, when such problems of safety and quality control have arisen, should the time between periodic inspections be extended. NISA asserts that it can carry out efficient and effective inspections, but the host regions see this as nothing but willful contempt for safety.

The mass media has pointed out that the reason why the system is being introduced is, quite simply, economics. They say, “The electric power industry has long demanded this as a ‘trump card’ for reducing costs” and “If shrinking the time that plants are shut down can increase the capacity factor by one point, Tokyo Electric’s profits will rise 11.5 billion yen, while Kansai Electric’s profits will rise 6.4 billion yen.”

NISA says that because the bulk of worker exposure to radiation occurs during periodic inspections, the new system will lead to a reduction in such exposure. There are other ways in which worker exposure should be reduced, but there are concerns that long-cycle operation will actually increase exposure, as a result of the increased concentration of corroded substances which have become radioactive.

NISA bases its claim that safety can be maintained under long-cycle operation on the absence of any observed increase in shutdowns from equipment failure during the experience of long-cycle operation in America and France. However, this experience is very limited. NISA’s explanatory documents acknowledge a maximum of 30 months between periodic inspections in America. From 2002 to 2004 the maximum was 26 months, while the average was 18.8 months. In France there are two categories, 12 months and 18 months. The longest time between periodic inspections was 23 months, but the average was only 12.8 months, which is actually less than the Japanese average of 13.6 months. The longest time between periodic inspections in Japan was 16 months. (See the note below for an explanation of the apparent inconsistency between actual maximum and average time between inspections and maximum permitted time(1).)

Including pre-2001 and post-2005 experience, the record only amounts to about 10 years. At the meeting of the Advisory Committee for Natural Resources and Energy (an advisory agency to the Minister of Economy, Trade and Industry) where the decision to introduce the system was made, one of the committee members pointed out that “In France too, when the time between periodic inspections was extended, there were detailed discussions between the utilities and the regulatory body. Based on those discussions, it was accepted only for those plant design types for which it was confirmed to be technically appropriate”.

To extend the time between periodic inspections in the absence of sufficient data, while at the same time ignoring the concerns of the local people is imprudent to say the least. Perhaps it would be better to call it reckless.

Baku Nishio (CNIC Co-Director)

1. According to IAEA’s PRIS database, these times include adjustment operation time during periodic inspections. This explains why actual maximum and average times exceed the maximum time allowed in Japan. The French figures can be explained by the fact that the 12-month and 18-month categories are not legally binding.

Print Friendly, PDF & Email

You may also like...