Monju survey

July 18, 2013

Nuclear experts in 2nd day of Monju fault survey

http://www3.nhk.or.jp/nhkworld/english/news/20130718_20.html

Japan's nuclear regulators on Thursday continued their geological survey at the site of a fast-breeder reactor on the Sea of Japan coast. They are trying to find out if there are any active faults that pose safety risks.

Nuclear Regulation Authority Commissioner Kunihiko Shimazaki and 3 other experts began their 2-day survey at the prototype Monju reactor in Fukui on Wednesday.

Thursday's survey focused on a linear fissure found in an off-site area southeast of the reactor. Some experts suspect the fissure to be part of an active fault.

Researchers also inspected the coastal area north of the reactor to see if any similar fissures exist, which would suggest an extension of the fissure in question.

After Wednesday's survey, the experts asked the reactor's operator, the Japan Atomic Energy Agency, to survey a wider area for possible faults.

The operator agreed and decided to carry out additional surveys to find out whether the fissure extends into the sea.

Jul. 18, 2013 - Updated 05:14 UTC

Regulators inspecting fault under Monju reactor

http://www3.nhk.or.jp/nhkworld/english/news/20130717_12.html

Japan's nuclear regulator is checking the country's 6 nuclear power plants built over faults.

On Wednesday, experts launched a 2-day examination of faults at the prototype Monju fast breeder reactor in Fukui Prefecture.

The team comprises Nuclear Regulation Authority commissioner Kunihiko Shimazaki and 3 other experts.

The reactor compound is over 8 faults. One is under the reactor. Experts say shifts could occur if an active fault about 500 meters west of the site moves in an earthquake.

The team was first briefed on locations of the faults by officials of the reactor's operator, the Japan Atomic Energy Agency.

They then saw where part of the active fault appears in the ground, and scraped the soil to get a clear view.

The government does not allow building of key reactor facilities above active faults.

If the fault under the reactor were determined to be at risk of moving with the active fault, the reactor would no longer be operable.

In the afternoon, the team was to visit a point where an extended section of the fault beneath the reactor can be observed.

Jul. 17, 2013 - Updated 04:55 UTC

Panel starts investigation on geologic faults at Monju reactor site

http://mainichi.jp/english/english/newsselect/news/20130717p2g00m0dm062000c.html

TOKYO (Kyodo) -- A team of experts appointed by the Nuclear Regulation Authority started a two-day investigation Wednesday on the activity of some geologic faults running beneath the Monju prototype fast-breeder reactor in Fukui Prefecture.

The Japan Atomic Energy Agency's Monju reactor is the fourth location visited by an NRA-led team to check whether shattered zones, or zones of crushed rock, at the site could move in the future and undermine the safety of the facility.

In quake-prone Japan, nuclear reactors are not allowed to be located directly above active faults. The Monju reactor sits above eight small shattered zones, which may move together with an active fault running about 500 meters west of the facility.

The Monju reactor has effectively been banned from operation in the meantime because of the operator's lax safety management. If the shattered zones are acknowledged to be active faults, it will be highly difficult to resume operation.

Japan has already spent over 1 trillion yen on the Monju project, hoping the facility would play a key role in the country's spent fuel recycling policy.

But the reactor has remained largely offline since it first achieved criticality in 1994, due to a sodium coolant leak and subsequent problems.

The investigation team is led by NRA commissioner Kunihiko Shimazaki and four other experts recommended by academic circles. One of the outside experts will not participate in the two-day field survey and will visit the site later.

Among the four nuclear facilities that have accepted NRA investigation teams, the NRA has reached a conclusion that the No. 2 unit at Japan Atomic Power Co. Tsuruga nuclear plant is located above an active fault. But the operator has argued against the assessment, which could leave the company with no option but to scrap the reactor.