A team of international nuclear safety experts has reviewed Japan's procedure to confirm the safety of its nuclear plants as dire economic conditions grip the country's power industry.
A mission to Japan lasting from 23 to 31 January saw a team of ten experts from the International Atomic Energy Agency (IAEA) and its member states spend time with Japan's nuclear safety regulator, NISA, which is conducting a two-stage assessment process to ensure nuclear plants have adequate protection against extreme external events.
While NISA continues its work to review the preliminary assessments, supported by the Nuclear Safety Commission and the Japanese Nuclear Energy Safety Organization, reactors are still closing one by one for mandatory safety inspections. Currently only three are in operation from a potential operating fleet of 44, not counting the ten Fukushima Daiichi and Daiini units.
The preliminary report from the IAEA team to the Japanese government said NISA and nuclear operators had "promptly addressed" emergency safety measures after the accident at Fukushima Daiichi. It contained a range of recommendations to NISA to ensure thorough and lasting improvements in safety are made.
|James Lyons, leader of the IAEA mission, at NISA headquarters in Tokyo
(Image: Gregg Webb / IAEA)
The Fukushima accident began after massive tsunami flooding disabled on-site power supplies as well as cooling. The overheating that followed saw three core melts and hydrogen explosions ruin four reactor units. In future, nuclear power plants in Japan and the world over must be better protected from extreme external events like those that hit Fukushima Daiichi - and better prepared to manage such a situation should it occur.
Shortly after the accident NISA demanded that Japan's nuclear power companies report on the safety margins of their power plants under Fukushima-like accident conditions in a 'primary assessment.' These documents are to be reviewed by NISA before a reactor can be granted permission to restart at the end of a mandatory inspection outage.
No date has been slated for the first restart, and even with the go-ahead from NISA power companies would still require approval from local prefectural governments. Although this is not a legal requirement, the deference traditionally shown by power companies to local officials has become mandatory in post-Fukushima Japan.
NISA has so far received 15 primary assessments including one relating to the third reactor at Kansai Electric Power Company's Ohi nuclear power plant, which was visited by the IAEA team. There they saw the new measures taken by Kansai, including new used fuel pool refill systems, mobile back-up generators and robust stores of emergency equipment.
The 'secondary assessment' of Japan's program will be an overall evaluation that relates closely to the stress tests carried out in the European Union and elsewhere. However, the IAEA said the secondary assessment is to "inform whether to continue or halt operations," implying that permanent closure of nuclear sites is a possibility. Many improvements to safety, site preparation and emergency management have been recommended in other countries, but none have so far suggested the permanent shutdown of a nuclear facility.
If nuclear reactors do not restart, Japan faces the challenge of meeting summer peak demand without a large part of its usual power supply, although it is thought that continued energy austerity might be able to bridge the gap.
The cost of this extended nuclear shutdown, however, is catastrophic: Importing an extra ¥4.3 trillion ($55 billion) of fossil fuel tipped Japan's trade balance into the red for 2011; and today Bloomberg reported financial results from six Japanese power companies that counted total losses of ¥463 billion ($6.0 billion) due to increased fossil fuel costs and idled nuclear capacity.
Researched and written
by World Nuclear News