All seven reactors of the Kashiwazaki-Kariwa nuclear power plant have been closed since the July 2007 Chuetsu-Oki Earthquake, but Tokyo Electric Power Company (TEPCO) began loading nuclear fuel into Unit 7 on November 8, 2008 with a view to starting system tests. Unit 7 is an Advanced Boiling Water Reactor (ABWR) with an electric power rating of 1,356 MW. It takes a full load of 872 fuel assemblies containing 150 tons of uranium and has 205 control rods. After the earthquake the fuel was removed from the reactor and transferred to the fuel pool. The fact that the same fuel was reloaded shows that a judgment was made that it was still fit for use. Although the formalities are not completely clear, if it is confirmed that the control rods still operate properly and the system tests are successful, the next step will be to carry out criticality tests.
On October 3 the Nuclear and Industrial Safety Agency (NISA) approved Tokyo Electric Power Company's (TEPCO) report on its assessment of Unit 7 at the level of individual items of equipment. In doing so, it accepted the integrity of Unit 7 at this level. The next step is to see whether the parts operate properly as a total system.
The latest meeting of a Niigata Prefecture sub-committee looking into equipment integrity and earthquake resistance and safety (chairperson Masaharu Kitamura) was held on November 12, but no agreement was reached about the integrity of the plant at the level of individual items of equipment, buildings and structures. Nevertheless, NISA has given the go ahead for system tests. The thinking appears to be that if preparations wait until agreement is reached, the plant will never be restarted. Even if the other six units have to wait, authorities want to show some progress by bringing Unit 7 to the point where it can be restarted. Step by step, keeping an eye on the situation, they are moving ahead. After system checks they will progress to start-up tests, trial operation and then to full operation.
It remains unclear whether the strain on Unit 7 equipment caused by the seismic movement exceeded the elastic range and resulted in plastic deformation (see NIT 125). Everyone, including NISA and TEPCO, agree that it is not possible to measure strain that does not exceed 2%. The only method available is to measure "hardness", but this method is not sensitive enough. It is suspected that strain in this range might exceed the range of elastic deformation.
During the November 12 meeting of the abovementioned subcommittee, cracks in the concrete of buildings at the plant were discussed. Two NISA officers attended the meeting and explained why NISA confirmed the integrity of the Unit 7 equipment. In response to questions by sub-committee members the NISA officers reluctantly admitted that some of the eleven cracks thought to have been caused by the earthquake were produced by plastic distortion. TEPCO tried to avoid the issue by saying vaguely that the conditions under which the cracks appeared were not laboratory conditions, so it could not give precise answers. The fact that NISA went beyond vague answers shows that there was no alternative but to admit that the strain applied to the buildings exceeded the elastic range. It begs the question, what about the machinery? Nevertheless, NISA stuck to its position that there are no safety problems.
Regarding the condition of the ground on which the plant is built, the following claims made by three local anti-nuclear groups are convincing.
1. The shift in the level of the reactor building is not just random error in the data.
2. The ground is not firm enough to support the plant and is still moving as an after effect of the earthquake.
3. There is plenty of evidence to suggest that the Madogasaka Fault has been active since the late Pleistocene Age.
By contrast, the responses by TEPCO and the central government's working group to these and other points are unconvincing. One reason is that the measurement data that TEPCO has submitted to the working group is quite arbitrary. Until questions about the ground on which all seven Kashiwazaki-Kariwa units are built are resolved, the plant should not be restarted.
The Group of Concerned Scientists and Engineers Calling for the Closure of the Kashiwazaki-Kariwa Nuclear Power Plant was established in August 2007. On November 12 this year they submitted demands to Yasuhisa Komoda, Director-General of NISA. They provide detailed evidence about four defects with the deliberations of the various central government committees, including the above three points. The fourth point related to the above-mentioned concerns about strain. In addition, they pointed out the following two problems.
1. TEPCO originally stated clearly that it would consider Unit 1 (BWR) and Unit 7 (ABWR) first, because they were representative of the two types of reactor at the Kashiwazaki-Kariwa site and because Unit 1 experienced a large seismic movement, while Unit 7 experienced a small movement. However, despite its original statement, TEPCO has prioritized assessment of Unit 7. It has submitted a final report on Unit 7 without even submitting so much as an interim report on Unit 1.
2. In order to assess the integrity of the plant it is necessary to study the overall damage and to make precise comparisons. It is not possible to generalize from analysis of a single unit.
On this basis they demanded that NISA not give permission for the restart of Unit 7. They also demanded a reply from NISA and an opportunity to discuss the matter by the end of November.
In October and November respectively, elections were held for the positions of governor of Niigata Prefecture and mayor of Kashiwazaki City. In each case the incumbent was re-elected. It can be expected that they will continue to adopt a cautious approach, prioritizing the safety and peace of mind of their citizens. It will be particularly interesting to see the approach taken by the mayor of Kashiwazaki, who was re-elected on a platform of local development that is not over-dependent on the nuclear power plant.
Yukio Yamaguchi (CNIC Co-Director)