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Restart KK-7: emergency cooling malfunctions

Nuclear Monitor Issue: 
#689
5951
06/06/2009
WISE Amsterdam
Article

In the latest issue of the Nuclear Monitor (688, published on May 7) we ran an article on the pressure to restart Kashiwazaki-Kariwa reactor number 7 in Japan. A few hours before printing the issue came the news that the reactor would be restarted in the next days. Too late to rewrite the article but just in time to do a “latest news” box. Just a few days after the restart the emergency cooling-system failed, twice.

On May 9, after months of intense pressure from Tokyo Electric Power Company (TEPCO) and the central government, the Governor of Niigata Prefecture and the Mayors of Kashiwazaki City and Kariwa Village gave their permission to TEPCO to restart Unit 7 of the Kashiwazaki-Kariwa Nuclear Power Plant (KK) for the first time since the 16 July 2007 Chuetsu-oki Earthquake. In doing so, they are gambling with the safety of the people of Niigata Prefecture and beyond.

Their decision flies in the face of scientific arguments presented in two subcommittees established by Niigata Prefecture to investigate the impact of the earthquake on the plant. Neither of these subcommittees has resolved crucial questions about the nature of the earthquake, the impact of the earthquake on the plant, or the future safety of the plant. In the end, pressure from TEPCO and the central government have prevailed over sound science.

In particular, the following issues have not been resolved (see Nuclear Monitor 688 for more details).

(1) Seismic Safety
TEPCO, the Nuclear and Industrial Safety Agency (NISA) and the Nuclear Safety Commission (NSC) argue that it is sufficient to set the magnitude of the design-basis earthquake at M7.0. By comparison, the Chuetsu-Oki Earthquake was M6.8 on the Japanese scale.

(2) Unstable Ground
The ground beneath the buildings is moving. The ground level has been measured on three occasions since the earthquake, but each time the direction and size of the inclination of the buildings was different.

(3) Seismic Safety of Equipment in Doubt
There are concerns that during an earthquake in excess of M7 the casing within which the recirculation pump motors are contained could buckle and break.

Important technical questions under the following three broad headings have not been answered:

  • "What magnitude earthquake should the plant be designed to withstand?"
  • "Why does the ground continue to move?"
  • "Can the plant withstand the next earthquake?"

As long as scientific answers to these questions are not found, there can be no basis for confidence in the safety of the plant.

TEPCO, the central government and the prefectural and local governments are making the same mistakes that have been repeated throughout the history of KK. As in the past, once again they have decided to sacrifice sound science and public safety for the sake of national policy.

Reactor malfunctions after restart

TEPCO began withdrawing the control rods at 1:53pm on May 9 and started up the reactor. Problems first arose that night at 11:15pm in a valve in the main steam system. More problems occurred on May 11. TEPCO's press release described the May 11 problems, which occurred at 6:43am and 6:53am, as follows:

"[W]hile performing an activation test of the reactor core isolation cooling system (RCIC), water level of the suppression pool went beyond the normal level...[T]he RCIC could not be shut down by normal procedure and had to be shut down manually at the site."

The problems led to a departure from the "Limiting Condition for Operation" stipulated in the Technical Specification. TEPCO had intended to start the turbines and begin sending electricity to Tokyo on May 15, but as a result of these problems it was not able to do so until May 19.

 

Sources: Statement of Protest, Citizens' Nuclear Information Center (CNIC), 8 May 2009 / Asahi Shimbun (Japan), 12 May 2009 / Nuke Info Tokyo, May/June 2009
Contact: Philip White (CNIC International Liaison Officer).
Tel: +81-3-3357-3800           
Email: [email protected]
Web: http://cnic.jp/english/

About: 
Kashiwazaki Kariwa-7