No active faults apparently under Sendai, Genkai, Ikata, Tokai and Onagawa plants

August 12, 2012

No active faults found under 5 N-plants

The Yomiuri Shimbun

http://www.yomiuri.co.jp/dy/national/T120811003383.htm

The Nuclear and Industrial Safety Agency has concluded five nuclear power plants have no active faults below their building sites.

NISA, the nuclear watchdog of the Economy, Trade and Industry Ministry, is looking into whether active faults exist below the sites of nuclear power plants nationwide. In a hearing of four experts held on Friday, the conclusion was reached that the five plants in question had no active faults below them, it said.

The five plants are: Kyushu Electric Power Co.'s Sendai plant in Kagoshima Prefecture and Genkai plant in Saga Prefecture; Shikoku Electric Power Co.'s Ikata plant in Ehime Prefecture; Japan Atomic Power Co.'s Tokai No. 2 plant in Ibaraki Prefecture; and Tohoku Electric Power Co.'s Onagawa plant in Miyagi Prefecture.

The experts examined whether faults below each plant's buildings could be subject to the following scenarios:

-- Cause quakes just below nuclear reactors.

-- Be pulled by active faults near the compounds and cause ground movement.

-- Cause ground movement from an earthquake that occurs in a distant place.

Based on past excavation survey results and other data, the experts concluded the five plants' sites are not susceptible to any of the three possible scenarios.

Meanwhile, NISA requested additional research to draw conclusions on Kansai Electric Power Co.'s Mihama and Takahama plants and Japan Atomic Energy Agency's Monju fast-breeder reactor, all in Fukui Prefecture, as it deemed the Mihama plant and Monju may fall into the second category and the Takahama plant into the third.

NISA has deemed Chubu Electric Power Co.'s Hamaoka plant in Shizuoka Prefecture and Chugoku Electric Power Co.'s Shimane plant in Shimane Prefecture fall into the third category.

(Aug. 12, 2012)

August 11, 2012

Monju, Mihama nuke plant sites must be checked for active faults: panel

http://mainichi.jp/english/english/newsselect/news/20120811p2a00m0na009000c.html

An expert panel to the Nuclear and Industrial Safety Agency (NISA) has demanded that the sites of the Monju prototype fast-breeder reactor and the Mihama nuclear plant in Fukui Prefecture be checked for active fault lines.

The move comes as part of NISA's survey of nuclear power plants across the country for active faults beneath the facilities. Following a call by the expert panel on Aug. 10, NISA is set to consider whether to order such on-site surveys for the Monju reactor run by the Japan Atomic Energy Agency (JAEA), and the Mihama nuclear plant operated by Kansai Electric Power Co.

An active fault line called the Shiraki-Nyu fault runs some 500 meters west of the Monju reactor and about 1 kilometer east of the Mihama reactors. Experts have previously pointed to the possibility that the crush zones -- areas of rock composed of stone fragments produced by seismic activity -- on the nuclear complexes' premises could shift in conjunction with the fault. If these crush zones have moved within the past 120,000 to 130,000 years, they are recognized as active, but JAEA and Kansai Electric have denied there have been any shifts in that timeframe.

Experts have called for on-site investigations citing lack of evidence in the operators' assertions and a need for a forum for debate while examining the actual sites.

Experts have also pointed to insufficient grounds for declaring Kansai Electric's Takahama nuclear plant in Fukui Prefecture safe, but NISA is mulling its response as there is no active fault running nearby.

The panel reviewed 10 additional nuclear plants operated by seven power companies on Aug. 10, completing the review of all 18 nuclear facilities across the country.

While NISA denied there are active faults running under Chugoku Electric Power Co.'s Shimane nuclear plant in Shimane Prefecture and Chubu Electric Power Co.'s Hamaoka nuclear plant in Shizuoka Prefecture, the agency said, "There is a need to examine the possibility that the earth (under those facilities) could shift when earthquakes occur in distant areas."

NISA will ask the operators of the two facilities to examine to what degree the ground would shift and what effect that would have.

Meanwhile, NISA approved reports filed by the operators of five nuclear plants stating there are "no active faults" running beneath them: the Genkai nuclear plant in Saga Prefecture and the Sendai nuclear plant in Kagoshima Prefecture, both operated by Kyushu Electric Power Co.; Shikoku Electric Power Co.'s Ikata nuclear plant in Ehime Prefecture; Japan Atomic Power Co.'s Tokai No. 2 Power Station in Ibaraki Prefecture; and Tohoku Electric Power Co.'s Onagawa nuclear plant in Miyagi Prefecture.

NISA's review of potential active faults underneath nuclear plants started in July, after suspicions emerged that Japan Atomic Power Co.'s Tsuruga plant in Fukui Prefecture may be sitting on an active fault line. In its previous meetings, the expert panel has pointed out that Hokuriku Electric Power Co.'s Shika nuclear plant in Ishikawa Prefecture is very likely located on top of an active fault line.

Since the central government does not allow nuclear reactor buildings to be built on active faults, reactors may face decommissioning if such faults are confirmed beneath them.