We are announcing the status of major inspections and restoration works and nonconformances
at TEPCO's Kashiwazaki-Kariwa Nuclear Power Station after the Niigata-Chuetsu-Oki Earthquake.
Inspection/Restoration Status
○ Inspection and restoration completed between November 14th to November 20th, 2008
(Completed on the following date)
• Unit No.1 Repair work of steam separator (Repair work):
November 17th
• Unit No.1 Main exhaust duct inspection and restoration (Ventilation system exhaust
stack inlet radiation monitor sampling pipe inspection):
November 18th
• Unit No.3 House transformer inspection (3A and 3B Carrying in) :
November 17th
• Unit No.3 Excitation transformer inspection (Carrying in) :
November 17th
• Unit No.3 Stack inspection (Inspection of stack radiation monitor sampling pipe):
November 16th
• Unit No.6 Stack inspection (Inspection of stack radiation monitor sampling pipe):
November 18th
• Unit No.7 Fuel-load work (Fuel-load work):
November 17th
• Unit No.7 Fuel-load work (Core status confirmation):
November 18th
• Unit No.7 Reactor internal pump input transformer inspection (Energization for
testing without load):
November 20th
• High-voltage start-up transformer No.3 inspection (Energization for testing without
load):
November 14th
○ Inspection and restoration to be commenced between November 21st to November 27th, 2008
(To be commenced on the following date)
• Unit No.1 Main exhaust duct inspection and restoration (Restoration of substruction):
November 27th
• Unit No.2 Main exhaust duct inspection and restoration (Restoration of substruction):
November 27th
• Unit No.3 Seismic reinforcement works (Seismic reinforcement works for the roof truss
of the reactor building) :
November 25th
• Unit No.7 Turbine inspection (Low-pressure turbine (A) restoration work of casing):
November 24th
• Unit No.7 System functional test (Reactor shut-down margin inspection):
November 18th*
• Unit No.7 System functional test (Functional test of control rod drive):
November 23rd
• Unit No.7 System functional test (Functional test of reactor containment vessel
isolation valve):
November 24th
• Unit No.7 System functional test (Functional test of automatic depressurization system):
November 25th
* Work schedules added and altered this week.
○ Work Schedule of Major Inspection/Restoration from November 16th to December 13th, 2008
• Work Schedule of the Main Inspection/Restoration of the Kashiwazaki-Kariwa Nuclear
Power Station in Response to the Niigata-Chuetsu-Oki Earthquake (during 4 Weeks)
....Appendix
(Reference)
Nonconformances Found in the Inspection and Restoration Works Performed after the
Niigata-Chuetsu-Oki Earthquake
Based on the "Public Announcement Regarding Nonconformance Found in the Inspection
and Restoration Works Performed after the Niigata-Chuetsu-Oki Earthquake", the Tokyo
Electric Power Company, Incorporated (TEPCO) provides this announcement containing
incidents information reported from November 13th to November 19th, 2008.
○ Incidents Information (relating to the Chuetsu-Oki Earthquake)
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< Reports from November 13 to November 19, 2008 >
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○ Other Findings
• Visual inspection was conducted for stack radiation monitor sampling pipes of Unit
No.1 and Unit No.3 after removing insulation. As a result of the inspection, damage
was found on an intake side pipe of sampling pump of Unit No.3, and a misalignment
was found on the joint of discharge side pipes of sampling pump of Unit No.1. These
incidents did not lead to any radiological impact to the environment. Additionally,
visual inspection was conducted for stack radiation monitor sampling pipes of Unit
No.2, 4, 5, 6 and 7 after removing insulation, and no additional damage was found
(announced on October 30th and November 13th, 2008).
Subsequently, visual inspection was conducted for ventilation system exhaust stack
inlet radiation monitor sampling pipe of Unit No.1 on November 18th, 2008 after
removing insulation, and no additional damage was found.
Investigation of the unit No.3 exhaust stack radiation monitor sampling pipe damage
revealed high concentration of salt on the surface of the pipe. Plumate pattern
characteristic of salt corrosion was found in the fracture surface and adjacent to
that pattern, another pattern characteristic of damage caused by external force was
found. Based on these findings, the pipe breakage was assumed to have happened due
to corrosion by salt that led to decreased strength that resulted in breakage when
seismic force was applied.
Investigation of the dislocation of the connection of the unit No.1 exhaust stack
radiation monitor sampling pipe was conducted. Since the dislocated anti-lightning
pipe connection was placed outside, misalignment between the monitoring building and
the pipe occurred due to the earthquake, which led to the dislocation of the relevant
connection.
Measures will be taken to periodically inspect the exhaust stack radiation monitor
sampling pipe as well as to replace, as necessary, the pipe with stainless steel
pipe resistant to corrosion and paint resin on the pipe surface to further protect
from corrosion.
Anti-lightning pipe connection was moved inside the building so that it will not be
dislocated by an earthquake.
Based on this incident, inspection will be conducted on ducts located outside as well
and the results will be publicized in the weekly report.
Appendix: Work Schedule of the Main Inspection/Restoration of the Kashiwazaki-Kariwa Nuclear
Power Station in Response to the Niigata-Chuetsu-Oki Earthquake (during 4 Weeks)
(PDF 40.2KB)
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