Ohi (Japan)

Map of Ohi

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2 *1120 MW PWR units; constructed by Westinghouse; grid connection in 1977/78
2 * 1120 MW PWR units; constructed by MHI; grid connection in 1991/92.

Facilities in Ohi

plantreactor typconstruction startoperation startshut down
Ohi-1PWR19721977
Ohi-2PWR19721978
Ohi-3PWR19871991
Ohi-4PWR19881992
2008-03-12

During a control rod operation test, in Ohi-2 one of the four rods constituting the D bank was found to be out of position. Power output was reduced to 75%.
(source: http://cnic.jp/english)

2007-11-07

"During a periodic inspection, while testing extraction and insertion of the control rods, the control rod position indication system showed one rod near the full withdrawn position, when all rods should have been fully inserted. Cause: Foreign material appeared to have fallen between the control rod cluster guide tube and the control rod preventinig it from movin into place.
(source: http://cnic.jp/english)

2007-09-03

The water level fell in the pressurizer and in the chemical and volume control tank. A leak was discovered around the primary coolant pump seal water injection filters. The reactor was shut down manually. The O-ring on the filter flange was broken.
(source: http://cnic.jp/english)

1996-09-16

Shutdown due to an electrical failure in generator and main transformer.

1995-10-27

False operation of condenser water discharche valve.

1995-10-24

254 SG tubes found damaged

1995-08-24

Damage of thermometer tube attached recently to coolant piping, -> shutdown.

1995-07-07

Steam leaked through a side tube attached to main FW piping.

1995-05-12

188 SG tubes found damaged during inspection.

1995-02-25

SG tube leak; failure of switching to external power line led to power loss to condensate water pump, causing secondary coolant release from main steam relief valve for 48 hours.

1992-01-16

Trouble with manual reactor shutdown circuit (found during testing).

1991-04-17

Metal fitting of CR guide tube detached and found at bottom of RPV during inspection.

1990-09-30

Radioactivity leak from fuel rod found during inspection.

1989-08-16

Increased radioactivity level of gases from RCS due to fuel rod damage.

1988-10-17

75 RC pump vane bolts found damaged during inspection.

1988-06-23

Thinning of incore neutron detector guide tubes and control rod cladding found during inspection.

1988-05-24

Fife workers exposed to radioactive water due to malfunctioning of containment spray during inspection.

1988-03-31

Primary coolant pump vane bolts found damaged during inspection, similar damage found afterwards in most PWRs.