Report on the impact of the Niigata-Chuetsu Offshore Earthquake on the Kashiwazaki-Kariwa Nuclear Plant
and response by Tokyo Electric Power Company (TEPCO), national and local governments and other bodies (progress in October 2007)
Date

TEPCO and other power utilities and JANTI (Japan Nuclear Technology Institute)

National and local government

TEPCO Press release: Progress report of internal inspection of No. 1 reactor (phase 2)
Notification of the results of the final verification of internal inspection of No. 1 reactor (Phase 2)<Inspection period>
September 14 – October 1, 2007
<Scope of inspection>
Upper part of reactor: flange reactor pressure vessel, guide rod, feed-water sparger, reactor core spray piping, reactor core spraysparger, core shroud upper ring, upper grid plate

Monday 1
October

Middle part of reactor: reactor core support plate, fuel support clasp, jet pump, Pipe arrangement for low-pressure core infusion, local
area output monitor,
Inside of the pool for temporary placement of equipments: steam dryer, steam-water separator<Results of inspection>- No abnormality such as damage, deformation or dropout was found in the upper and middle parts of the reactor, or steam dryer,
which was unloaded for regular inspection and temporarily placed in the pool used for temporally placement of equipments.
- As a result of inspection conducted on 27 September concerning steam-water separator, which was unloaded for regular inspection
and temporarily placed in the pool used for temporally placement of equipments, as in the case of steam dryer, deformations wereidentified in the feet used for temporary placement (4 of 4) and the guide pin (2 of 2) used to determine the location at the time of
installation inside of the reactor. Te feet used for temporary placement and the guide pin are complementary equipments ofsteam-water separators and do not have impact on te functions or the structures.
- In relation to the deformation of the feet of steam-water separator used for temporary placement, some damages were found on thefloor of the pool used for temporary placement of equipments. However, no water leakage from the said area was identified.
(Already notified on 27 September, 2007)
NISA press release: Survey/ Operation and management of countermeasure committee/ facility’s integrity
evaluation WG (2nd meeting)<Venue>11:00-11:30
12:30-13:30

Tuesday 2
October

13:45-15:45
16:15-17:15

2F, the Kashiwazaki-Kariwa Nuclear Power Station Disaster Prevention Center, Niigata
Prefecture
Niigata Center, BWR Operator Training Center Co., Ltd.
Simulated reproduction of response status on the operating floors in the case when K-4 andK-2 earthquake hit was executed at BTC.
Kashiwazaki-Kariwa Nuclear Power Station of TEPCO
2F, the Kashiwazaki-Kariwa Nuclear Power Station Disaster Prevention Center, Niigata
Prefecture<Agendum>+ On-site survey of the Kashiwazaki-Kariwa Nuclear Power Station
Nuclear Safety Commission: Special committee on nuclear power safety standard/ policy
On-site survey relating to protection from fire caused by earthquake at nuclear power stations

Friday 5
October

conducted by the section meeting on protection measure against fire
Executed to grasp the current status of efforts made to reinforce protection measures against fire caused byearthquakes at power stations, in terms of both facility and management of nuclear power stations.
TEPCO Press release: Regarding the result of inspections of main exhaust duct (aboveground and underground parts)<Outline of non-conformances>- Inspection was started from 10 September concerning the creeps of main exhaust duct of Nos. 1 through 5 reactors caused by the
impact of the earthquake. As a result, cracks were identified in 2 parts of 18 parts of the bellows (already notified on 17 July and
11 September).
- Then, inspection of underground main exhaust ducts of Nos. 2, 4, and 5 reactors (no underground exhaust duct exists in Nos. 1 and 3
reactors) was started on 2 October. As a result of the inspections, some creeps of duct covers were confirmed as regards 9 parts of
16 parts of bellows. As a result of inspection of the said 9 parts by detaching the duct covers, no abnormality in particular was

NISA press release: Impact of Earthquake (Report No. 28)
⁻ Received information from TEPCO as mentioned in the left⁻ With respect to information provided at this time on the cracks in the main exhaust duct of No. 1 Unit,abrasion inside of the fuel pool of No. 7 unit, and the crack in the concrete inside of the water discharge
channel of No. 7 unit, NIPA understands that necessary measures will be taken within the management
mechanism against non-conformance by TEPCO. NIPA will continue to check such progresses.
⁻ Will continue to check if damages or significant deformations are found during inspections inside of thereactors from Unit No. 1 to 7.

identified although there was some deformation in the bellows inside the ducts.
- In addition, as regards the main exhaust stack duct (parts above ground), 7 cracks were newly identified in the same part of the same
bellows as the one in which cracks were found in the previous inspection. (Maximum: about 2 cm, diameter of the duct: about 4 m,
duct circumference : 13m)
- With respect to the 9 parts of the bellows in the underground parts of Nos. 2, 4 and 5 reactors, where creeps were found, theconcentration of radioactive materials, the concentration of surface contamination and radiation dose rate were measured before
detaching the duct covers. Then, the concentration of surface contamination was measured in the parts where the duct covers weredetached. No radioactive material was found in either part, and no impact of radioactivity to the outside was identified.
- Furthermore, with respect to the newly identified 7 cracks in the parts above ground of No. 1 reactor, the concentration of surface
contamination was measured. No radioactive matter was detected in either part, and no impact of radioactivity to the outside was
identified.
<Response>
Immediately implement temporary repairs of the cracks in the main exhaust duct (parts above ground) of No. 1 reactor.
TEPCO Press release: Regarding non-conformances in post-earthquake inspection and restoration program (weekly report dated
4 October)
Announcing the status of major inspections and restoration works (from September 30th to October 27th, 2007) and non-conformanceat TEPCO's Kashiwazaki-Kariwa NPS after the Niigata-Chuetsu-Oki Earthquake.
1. Inspection/restoration Status
1. Inspection/ Restoration Status+ Inspection and restoration completed between September 28th to October 4th, 2007
- Unit No.1 In-core inspection (Phase2):
Inspection completed on October 1st- Unit No.2 Reactor building ceiling crane inspection:
Inspection to be completed on October 4th- Unit No.5 Reactor building ceiling crane inspection:
Inspection completed on September 28th
- Unit No.6 Reactor building ceiling crane inspection:
Inspection completed on October 2nd- Unit No.6 Turbine building ceiling crane inspection:
Inspection to be completed on October 4th- Unit No.7 Refueling floor service tools inspection (stud tensioners, etc.):
Inspection completed on October 1st- Unit No.7 Turbine building ceiling crane inspection:
Inspection to be completed on October 4th- Unit No.7 Removal of spent fuel pool underwater work platform:
Inspection completed on September 30th
- Standby Gas Treatment System verification run:Inspection completed on October 2nd- Fuel pool cooling water system back up pump verification run:Inspection completed on September 28th
+ Inspection to be commenced between to October 5th to October 11th, 2007.
- Unit No.1 House transformers (1B) inspection (oil extraction/ internal inspection)- Unit No.1 Excitation transformers inspection (oil extraction/ internal inspection)- Unit No.2 Restoration for the blowout panel of reactor building- Unit No.4 Refueling floor service tools inspection (stud tensioners, etc.)- Unit No.6 Turbine internal inspection- Unit No.7 Preparation to transport main transformers out of the factory- Unit No.7 In-core inspection- Unit No.7 Turbine internal inspection- Unit No.7 Main generator inspection- Solid Waste Storage Facility soundness confirmation⁻ Inspectors of NIPA are currently engaged in work to verify detailed facts, such as causes of events, etc. withrespect to the plant conditions surveyed by TEPCO.
⁻ Currently, no significant change is found in the main exhaust stack radiation monitors or the monitoring
posts.

2. Non-conformances Found in the Inspection and Restoration Works Performed after the Niigata-Chuetsu-Oki earthquake
This announcement contains incidents information reported from September 27th to October 3rd 2007 and the occurrence status of
non-conformances (that have been deliberated) reported from September 20th to 26th, 2007.
1)Incidents Information (related to the Chuetsu offshore earthquake)
From Sept. 27th to October 3rd, 2007
Number of Incidents by Announcement Category(Total Figure from Aug. 10th, 2007)(Total Figure from Aug. 10th, 2007)
No. ofReported
Events

0
(1)

I

0(0)

II
III

0(0)
0(1)

<Reports from September 27 to October 3rd , 2007>
Announcement
Date of
Title of Report
StatusCategory
DetectionIIIIII
2) Information on Non-conformances (those related to : the Chuetsu offshore earthquake:;
Grades As – non-graded)
From Sept. 20th to 26th, 2007
(Total Figure from July 16th, 2007)
No. ofReported
24(2,850)
Incidents
3) Other Findings- Unit No.7 Visual inspection of inside the spent fuel pool in connection to the removal of the underwater work platform (removed
on September 28th). Confirmed 4 minor scratches on the legs of the work platform legs, scratches on the handle of 3 fuelbundles, and minor scratch on the wall of the pool.
- Unit No.6 Completed post-restoration inspection for 3 parts of damage to the reactor building ceiling crane drive joint (inspection
completed and begun use of the crane on October 2nd).
- Units No.6 and No.7 Confirmed crack inside the discharge canal concrete during inspection.
TEPCO Press release: Regarding the detection of well liner drainage water of No.7 reactor
On 8 October 2007, it was found that water was collected inside of the level gauge of the pipe arrangement connected to the well linerof the reactor. As a result of monitoring the tendency of water collected in the level gauge, and analyzing the water collected in the level
gauge, traces of radioactive materials (antimony 124, etc.) were detected.

Tuesday 9
October

Consequently, we assumed that the water detected was part of water used for filling the upper part of the reactor that was discharged
into the level gauge through the liner. Discharge of water into the level gauge is continuing even now (approx. 500 cc /hour). In thedays ahead, it is planned to remove the fuel and conduct inspection of the reactor core and the exposed parts, as well as the liner. No
impact of radioactivity to the outside was caused by this incident.

Nuclear Safety Commission: On-site survey of the Kashiwazaki-Kariwa Nuclear Power Station by thecommittee members
Executed on-site verification concerning the state of facilities of the power station(Locations where on-site verification was conducted)
No. 7 unit:+ Reactor building⁻ Operating floor (verification of the alignment of fuel and control rod)⁻ Upper part of dry well⁻ Residual heat removal system pump chamber (B)⁻ + Turbine building operating floor
TEPCO Press release: Regarding” The Report on Failures at Nuclear Reactor Facilities” in relation to the impact of the Niigata NISA press release: Impact of Earthquake (Report No. 29)
Chuetsu offshore earthquake⁻ Received report and information from TEPCO as mentioned in the left.
The Tokyo Electric Power Company, Inc. submitted reports regarding the following items to the Minister of Economy, Trade and⁻ With respect to leakage of water containing radioactive materials into the non-controlled
Industry in accordance with "Article 19-17, Rules on the Installation, Operation and Others of Commercial Power Rectors".
areas in reactor building in Unit No. 6, inundation on the operating floors of reactor
1. Leakage of water containing radioactive materials into the non-controlled areas in the Unit 6 reactor building
Thursday 11 [Outline of the Event]buildings in Units Nos. 1 to 7, damaged travel transmission joints of the overhead
Octobertraveling crane in the reactor building of Unit No. 6, the study / countermeasure
It was confirmed that, on the refueling floor of fourth of the reactor building (controlled area), a sloshing (stirring of water surface
caused by seismic motion) due to the Niigata-Chuetsu-Oki Earthquake had caused the water containing radioactive materials to flow out
committee in charge of nuclear power stations affected by the Niigata Chuetsu Offshoreof the spent fuel pool into the mezzanine floor (non-controlled area) between the second and third floors through a electrical wire
Earthquake, and its working groups will examine these issues in detail. Furthermore,
conduit tube connected to the power supply box of the refueling machine, and then run down into the third floor (non-controlled area)
as regards other reported non-conformances, we will check countermeasures for theand into the non-radioactive drainage collecting tank on the first basement (non-controlled area), and had been finally released into theprevention of recurrence of events and so on to be executed by TEPCO in the future.

sea through the discharge outlet. The amount of water released and its radioactivity was estimated to be about 1.2m3 and about 9 × 104
Bq, respectively.
[Possible Causes]
Based on the results of our investigations, we estimated the cause of the leakage of water containing radioactive materials into thenon-controlled areas to be as follows:
・ The water flowed into the power supply box leaked into the electrical wire conduit tube through a clearance which was formed byeither insufficient design consideration or a defective seal in the tube penetration of the power supply box.
・The water which ran into the embedded electrical wire conduit tube dripped from the upper air conditioning duct of themezzanine floor and onto the surface of the third floor through the opening of the mezzanine floor.
As a result, we estimated that the water which dripped down onto the surface of the third floor had flowed through the drain port on thethird floor into the non-radioactive drainage collecting tank placed on the first basement, and subsequently had been released by thedrain pump into the sea through the discharge outlet.
[Preliminary Measures]
As an emergency measure, the tube penetration of the power supply box in the refueling machine placed on the forth operating floor of
the reactor building was refilled with a sealant to improve its sealing characteristic.
The leaked water was completely wiped off from the floors. The water accumulated in the non-radioactive drainage collecting tank on
the first basement of the reactor building was transferred by means of a temporarily installed pump into the high-conductivity effluent
collecting tank placed within the controlled area in the turbine building, and treated in the liquid waste treatment system. For theradioactive water which was released from the non-radioactive drainage collecting tank on the first basement of the reactor building into
the sea through the discharge outlet, safety measures were taken so as to ensure that the drain pump on the tank would not automaticallystart. In the future, we plan to execute decontamination works for the water leakage route.
As permanent measures, we will consider design and structural improvements to be made for the tube penetration of the power supply
box to be impermeable. In each plant, investigations will be made also on penetration between controlled and non-controlled areas toimprove their sealing characteristics, if necessary.
2. Inundation on the operating floors of reactor buildings in Units Nos. 1 to 7
[Outline of the Event]
Following the Niigata-Chuetsu-Oki Earthquake that occurred on July 16, 2007, our team begun surveying the site of the nuclear power
station at around 11:00 a.m. on the day. As a result, it was confirmed that the entire refueling floors (controlled area) of the reactor
buildings in Units 1 to 7 were inundated with water that flowed out of their respective spent fuel pool. For all units, analyses of the waterthat flowed out confirmed that radioactive materials were contained.
- Unit 1 (Approx. 4.1 ×100 bq/cm3)- Unit 2 (Approx. 6.7 ×101 bq/cm3)- Unit 3 (Approx. 7.8 ×101 bq/cm3)- Unit 4 (Approx. 2.6 ×101 bq/cm3)
1- Unit 5 (Approx. 1.9 ×10 bq/cm3)
1- Unit 6 (Approx. 1.4 ×10 bq/cm3)
1- Unit 7 (Approx. 2.7 ×10 bq/cm3)[Possible Causes]
Based on the results of investigations, we estimated that the inundations on the refueling floors of the reactor buildings in Units 1 to 7
had been caused by the water that flowed out of their respective spent fuel pools due to the seismic sloshing.
[Preliminary measures]
The water that had flowed out of the spent fuel pool onto the refueling floors in Units 1 to 7 was completely wiped off anddecontaminated by July 27.
Based on results of investigations and reviews on seismic measures to be conducted, we will take necessary measures in the future.
3. Damaged travel transmission joints of the overhead traveling crane in the reactor building of Unit No. 6[Outline of the Events]
After the Niigata-Chuetsu-Oki earthquake occurred on July 16, 2007, during equipment inspection conducted on July 24, damages wereconfirmed in 4 out of 2 wheel-side cross-pins on the south-side and north-side travel gears for the overhead traveling crane driving shaft.
On August 3, subsequent investigations and checking works also detected that one motor-sided cross pin of the travel transmission joint
mounted on the south-side travel gear had been damaged; totaling 3 out of 4 cross pins that were damaged.
The joints with damaged cross pins were removed, and submitted for a fractography examination. The results indicated no sign of metal
fatigue or any rust sticking considered as a trail of corrosion was found on the fracture surfaces.
[Possible Causes]
Based on the results of the investigations, we estimated that the travel transmission joints of the overhead traveling crane in the reactor
building of Unit No. 6 were damaged by the following causes:- When the earthquake occurred, the overhead traveling crane was at a halt with brakes stopping the traveling wheels.
- The seismic motion forced the traveling wheels of the overhead traveling crane in the reactor building to move with brakes still
stopping the traveling wheels.
- Since the traveling force of the crane was blocked by the wheel brake, it led to an excessive force on the transmission joints
placed between the traveling wheels and the motor and caused the damage.
[Preliminary Measures]
The set of travel transmission joints with damaged cross pins were replaced with new products (of the same model).
A detailed evaluation of seismic loads will be conducted accordingly.

⁻ Continue to check if any damage or significant deformation is found during theinspections of inside of the reactors in Units Nos. 1 to 7.
⁻ Inspectors of NIPA are currently engaged in work to verify detailed facts, such as causesof events, etc. with respect to the plant conditions surveyed by TEPCO.
⁻ Currently, no significant change is found in the main exhaust stack radiation monitors or
the monitoring posts.
NISA: Chuetsu Oki Earthquake Nuclear Power Plant Investigation and Countermeasures Committee
WG on internal fire protection systems and incident reporting structures in relation to the
Chuetsu oki earthquake (3rd session)
Issues relating to:(1) Liaison and communication structures(2) Internal fire protection(3) Other

TEPCO Press Release: Non-conformances Found in the Inspection and Restoration Works Performed after the
Niigata-Chuetsu-Oki Earthquake (Weekly report dated October 11th)
We are announcing the status of major inspections and restoration works (from October 7th to November 3rd, 2007) andnon-conformance at TEPCO's Kashiwazaki-Kariwa NPS after the Niigata-Chuetsu-Oki Earthquake.
1. Inspection/Restoration Status+ Inspection and restoration completed between October 5th to 11th, 2007
- Unit No. 2, 4 and 5 Main exhaust ducts inspection (in-trench duct): Inspection completed on October 5th- Unit No. 4 Turbine building ceiling crane inspection: Inspection completed on October 5th- Unit No. 6 Main transformers inspection (oil extraction/inner inspection): Inspection completed on October 6th- Unit No. 7 Reactor head opening: Inspection completed on October 8th- Unit No. 7 Discharge canal inspection: Inspection completed on October 10th
+ Inspection to be commenced between to October 12th to October 18th, 2007.
- Unit No. 1 Excitation transformers inspection (oil extraction/inner inspection)- Unit No. 2 House transformers (2A) visual inspection preparation- Unit No. 2 Removal of spent fuel pool underwater work platform- Unit No. 3 Main transformers inspection (oil extraction/inner inspection)- Unit No. 3 House transformers (3A) inspection preparation and inspection (oil extraction/inner inspection)- Unit No. 3 Excitation transformers visual inspection- Unit No. 3 Restoration for the blowout panel of turbine building- Unit No. 7 Main generator inspection- Inspection of low-voltage start-up transformer 3SA (oil extraction/inner inspection preparation)- Dismantling of Arahama-side arrestor steel tower+ Work Schedule for Major Inspection/Restoration from October 7th to November 3rd, 2007
- Work Schedule of the Main Inspection/Restoration of Kashiwazaki-Kariwa Nuclear Power Station in Response to the
Niigata-Chuetsu-Oki Earthquake (during 4 Weeks)
2. Non-conformances Found in the Inspection and Restoration Works Performed after the Niigata-Chuetsu-Oki Earthquake
Incidents information reported from October 4th to 10th, 2007 and the occurrence status of non-conformances (that have been
deliberated) reported from September 27th to October 3rd, 2007.
1) Incidents Information (relating to the Chuetsu-Oki Earthquake)
From October 4th to 10th , 2007
Number of Incidents by Announcement Category(Total Figure from Aug. 10th , 2007)(Total Figure from Aug. 10th, 2007)
No. ofreported
events

1
(2)

I

0(0)

II
III

0(0)
1(2)

<Reports from October 4th to 10th, 2007>
Announcement
Date of
Title of Report
StatusCategory
DetectionI
II
Detection of drain water from Detection of radioactive water flowing in through the
October 9thIII
the well liners at the Nuclear liner into the level gauge, when filling the upper
2007
Power Station Unit No. 7
reactor. (about 500cc/ hour, with radioactivity)
2) Information on Non-conformances (those related to: the Chuetsu-Oki Earthquake; Grades As - non-graded)
From Sept. 27th to October 3rd, 2007
(Total Figure from July 16th, 2007)
No. of22(2,872)
Reported
Incidents
3) Other Findings
Unit No. 2, 4 and 5: Observed creeps of ducts at 9 bellows out of 16 when inspecting the underground part of main exhaust
ducts. No abnormality found despite deformation of bellows. No radioactive materials detected at the creeps at 9 bellows as a

result of the measurement of surface contamination concentration, and there is no impact of radioactivity on the outside.
Unit No. 1 and 3: Re-checked the aboveground part of main exhaust ducts with the increased number of air blower/ evacuatormachines and newly observed 7 cracks at Unit 1. No radioactive materials detected at the cracks as a result of themeasurement of surface contamination concentration, and there is no impact of radioactivity on the outside. The 7 cracks
have been temporarily fixed on October 4th.
TEPCO Press Release: Geological surveys planned at the premises of Kashiwazaki-Kariwa Nuclear Power Station (NPS) andadjoining land area (Second survey of land area)(1) Execution of survey of soil deformability in order to assess subsidence and liquefaction of ground caused by the late earthquake,
which had been not yet determined.
⁻ Make assessment of subsidence and liquefaction of ground in the power station premises, which will be reflected in the repair
works in the future⁻ Survey of ground deformation will cover an extensive area encompassing the Nagaoka Plain Western Rim Fault Zone inaddition to the immediate land area adjoining the Nuclear Power Station premises, which will be reflected in the evaluation ofseismic safety.
(2) Execution of survey of representative faults in the Power Station premises and immediate areas adjoining the Power Station taking
into account views of the community⁻ Execute survey of faults in the power plant premises and immediate areas adjoining the power plant premises, which will bereflected in the evaluation of seismic safety
NISA: seismic and structural design sub-committee joint earthquake, tsunami, geology and ground WG (1stsession)
3. Issues relating to:(1) Scope of investigation into the seismic resistance of and safety levels at the Kashiwazaki-Kariwa nuclear facility
during the Chuetsu oki earthquake in Niigata prefecture(2) Progress of the investigation into the seismic resistance of and safety levels at the Kashiwazaki-Kariwa nuclear
facility during the Chuetsu oki earthquake in Niigata prefecture

Friday 12
October

Monday15 October

TEPCO Press Release: Establishment of the “Countermeasure Center for the Niigata Chuetsu Offshore Earthquake” andreinforcement of disaster prevention structure at the Nuclear Power Station
TEPCO will execute internal reorganization of the company as follows in order to further strengthen the post-earthquake responses
following the Niigata Chuetsu offshore earthquake.
+ Establishment of the “Countermeasure Center for the Niigata Chuetsu Offshore Earthquake”
The “Countermeasure Center for the Niigata Chuetsu Offshore Earthquake” will be newly established in the Nuclear Power Plant
Management Department of the headquarters as of October 15th.
“Countermeasure Center for the Niigata Chuetsu Offshore Earthquake” will be newly established in order to unify the functions ofexecuting the response operations to Niigata Chuetsu Offshore Earthquake and supporting the Nuclear Power Station, as well as
further improve the quality of service and ensure safety.
From now on, the Nuclear Power Station and the headquarters will work as one to forcefully promote the inspection/ restoration of the
facility and examination of seismic safety, with the “Countermeasure Center for the Niigata Chuetsu Offshore Earthquake” as thecentral player.
+ Reinforcement of disaster prevention system at the nuclear power station
Currently, each department at the Nuclear Power Station is mainly in charge of disaster prevention efforts against natural disasters suchas tyhoon (sever tropical storms) and fires, as well as disaster prevention caused by nuclear power events such as release ofradioactive materials to the outside. But, in the future, in order to realize “Disaster-resistant nuclear power station”, we have decided
to unify the disaster prevention system of nuclear power stations by the end of FY2007.
Toward this goal, “Disaster Prevention and Safety Group” will be established in the Nuclear Power Station Management Departmentof the headquarters as of October 15th to prepare this program.
TEPCO Press release: Internal inspection of No. 7 reactor
Workers began removing the fuel from the No. 7 reactor on October 11 to enable internal inspections. They then began removing thecontrol rods, and found that one of the control rods could not be removed.
All of the fuel next to this fuel rod has been removed. This does not impact on the safety of the fuel rod, which is securely supported bybrackets.
Investigation is continuing into the cause of the problem.

Thursday 18
October

NISA Press release: Earthquake update (Report No. 30)- Information received from TEPCO as per left-hand column- Information was received today that during the removal of fuel from the No. 7 reactor, which began on October
11, it was discovered that one of the fuel rods had become separated from the drive mechanism andconsequently could not be removed. NISA will take action as appropriate based on the impending investigation
by TEPCO.
NISA
is still in the process of conducting internal inspections of the Nos. 1 through 7units to check for damage
TEPCO Press release: Nonconformities identified in post-earthquake inspection and restoration program (Weekly report forand significant deformation
October 18)
NISA inspectors are currently investigating the causes and other details at the plants based on TEPCO findings
Notification of inspection and restoration process at Kashiwazaki-Kariwa Nuclear Power Plant following the Niigata Chuetsu oki- There are no significant changes in the main exhaust stack radiation monitor and monitoring posts
earthquake (from October 14 to November 10 2007) including nonconformities
1. Inspection and restoration+ Inspection/restoration work completed between October 12 and 18- No. 1 reactor: removal of water from B5 floor of combined reactor chamber completed October 12- No. 1 reactor: internal transformer (1B) oil clean-up/internal inspection completed October 12- No. 1 reactor: excitation transformer oil clean-up/internal inspection completed October 18

- No. 2 reactor: inspection of fuel exchanger completed October 16- No. 2 reactor: inspection of operating floor service tools (such as stud bolt tensioner) completed October 13- No. 2 reactor: removal of underwater workbench from spent fuel pool to be completed by October 18- No. 5 reactor: inspection of ceiling crane in turbine building – completed October 17+ Inspection/restoration work due to commence between October 19 and 25 2007
- No. 1 reactor: inspection of fuel exchanger- No. 2 reactor: opening of reactor and internal inspection- Nos. 2, 6 and 7 reactors: preliminary preparations for inspection of reactor vessels- No. 2 reactor: exterior inspection of internal transformer (2A), oil clean-up and preparations for internal inspection- No. 2 reactor: preparations for external inspection of internal reactor (2B)
- No. 3 reactor: inspection of operating floor service tools (such as stud bolt tensioner)- No. 3 reactor: preparations for internal inspection and oil clean-up of excitation transformer- No. 4 reactor: inspection of fuel exchanger- No. 5 reactor: opening of reactor- No. 5 reactor: confirmation of conditions inside turbine- No. 7 reactor: inspection of main power generator- No. 7 reactor: preparations for internal inspection and oil clean-up of internal transformers (7A, 7B)- Oil clean-up and internal inspection of low startup transformer 3SA
2. Nonconformities identified in inspection/restoration work following the Niigata Chuetsu oki earthquake
Report of issues identified in the period 11 – 17 October 2007 and nonconformities (as per discussions) occurring in the period 4 –10 October 2007
1) Issues related to the Chuetsu oki earthquake
11 - 17 October 2007
By category (cumulative total since 10 August 2007)(cumulative total since 10 August 2007)
No. ofissues

0
(2)

I

0 (0)

II
III

0 (0)
0 (2)

<4 – 10 October 2007>
Date
Category
Name
Description
identified
I
IIIII
2) Nonconformities (related to Chuetsu oki earthquake: As excluded)
4 - 10 October, 2007 (cumulative total since 16 July 2007)No.
26 (2,898)
3) Other- Report on inspection of solid waste storage drums, which began on October 9, will be provided during the next monthly progress
report on inspection and restoration work
- The spent fuel pool of the No. 2 reactor was inspected in conjunction with the removal of the underwater workbench from the pool(completed October 17). Minor grating was discovered in two places on the legs of the workbench frame, and also on the sides ofthe pool (inspection to be completed on October 18)- Inspection of the drainage channels in the Nos. 6 and 7 reactors revealed concrete cracking in the No. 7 reactor drainage channel(inspection completed October 10)

Sunday 21
October

TEPCO Press release: water leak in restricted area within No. 7 reactor building
Workers noticed water seeping from the wall in the vicinity of the elevator in a restricted area on the 2nd floor of the reactor building
during a regular patrol on October 20, and also observed water collected on the floor.
Samples were immediately taken for analysis. No radioactivity was detected. The wall was repaired and cured in order to stem theseepage, which had not abated, and the outcome of the repairs was monitored.
Further water samples were taken on October 21. This time, radioactive substances were detected: cobalt 60 and cesium 137. The
volume of water was approximately 6.5 liters, and the measured radioactivity was 250 Bq (equivalent to approximately 30 cm3 ofradon spa water). The water leak was confined to the restricted area, and there was no radiation impact beyond this area. The cause isstill under investigation.
The concrete wall is not designed to airtight or watertight specs; the cracks are extremely fine and are not considered to have any
impact on the structural integrity or strength of the wall.

Tuesday 23
October

TEPCO Press release: water leak in restricted area within No. 7 reactor building (continued)(Water seeping from seams in concrete wall)
Further investigation revealed a minor amount of seepage from seams in the concrete floor at the northern end of the third floor of thereactor building. The water was analyzed and found to contain radioactive cobalt 60. The total volume was approximately 200 cm3 andthe measured radioactivity was 0.8 Bq (equivalent to 0.1 cm3 of radon spa water). The water leak was confined to the restricted area, andthere was no radiation impact beyond this area.
(Leakage into liner detection piping flow glass)
A check was performed on the internal walls of reactor well liner and spent fuel pool liner detection pipes where water had collected in
the flow glass, as part of the wider investigation into leakage from the reactor well liner. Analysis of samples found traces of radioactive
substances such as cobalt 60 and serium 137. The volume of water in the flow glasses was minimal. It was disposed of via the normal
waste liquid treatment process. It did not enter pipes beyond this area.

NISA: WG on Seismic Safety and Structural Design (6th session)
Topics(1) Investigation of seismic safety standards at the Kashiwazaki-Kariwa nuclear facility in the Niigata Chuetsu
oki earthquake(2) Screening standards and criteria employed in the construction permit

No abnormality indicating a leakage has been found in the water level of the spent fuel pool or in the level gauge of pipes connected tothe pool liner.
TEPCO Press Conference: nonconformities identified in post-earthquake inspection and restoration program (weekly report dated NISA Press release: Earthquake update (31st report)
October 25)- Information/reports received from TEPCO as per left-hand column
Notification of inspection and restoration process at Kashiwazaki-Kariwa Nuclear Power Plant following the Niigata Chuetsu oki- An in-depth investigation will be conducted into the circumstances behind the control rod that could not be
earthquake (from October 21 to November 17 2007) including
removed, and also into the radioactive water leak within the reactor building
1. Inspection and restoration- Inspection of the Nos. 1 through 7 reactors for damage and significant deformation is continuing+ Inspection/restoration work completed between October 19 and 25- NISA inspectors are currently investigating the causes and other details at the plants based on TEPCO- No. 2 reactor: reactor opening process – completed October 24
findings- No. 3 reactor: internal inspection and oil clean-up of internal transformer (3A) – completed October 22- There are no significant changes in the main exhaust stack radiation monitor and monitoring posts- No. 5 reactor: inspection of fuel exchanger: completed October 19- No. 5 reactor: inspection of operating floor service tools (such as stud bolt tensioner) completed October 19- No. 6 reactor: internal check of turbine - completed October 25- No. 6 reactor: removal of internal transformer to factory - completed October 25- No. 7 reactor: removal of main transformer to factory - completed October 25- Oil clean-up and internal inspection of low startup transformer 3SA - completed October 25- Building preparation work - completed October 22+ Inspection/restoration work due to commence between October 26 and November 1 2007
- Nos. 1, 3 and 5 reactors: preliminary preparations for inspection of reactor pressure vessels- No. 1 reactor: general inspection of main transformer
Thursday 25- No. 1 reactor: preparations for internal inspection and oil clean-up of main transformer
October- No. 2 reactor: preparations for removal and transportation of main transformer to factory- No. 2 reactor: general inspection of internal transformer (2B); preparations for external and internal inspection and oil clean-up- No. 3 reactor: oil clean-up and internal inspection of excitation transformer- No. 5 reactor: internal inspection- Nos. 5, 6 and 7 reactors: inspection of reactor pressure vessels- No. 7 reactor: inspection of reactor well (commenced October 25)- No. 7 reactor: inspection of main power generator
2. Nonconformities identified in inspection/restoration work following the Niigata Chuetsu oki earthquake
Report of issues identified in the period 18 - 24 October 2007 and nonconformities (as per discussions) occurring in the period 11 23 October 2007
1) Issues related to the Chuetsu oki earthquake
18 - 24 October 2007
By category (cumulative total since 10 August 2007)(cumulative total since 10 August 2007)
No. ofissues

1
(3)

I

0 (0)

II
III

0 (0)
1 (3)

<4 - 10 October 2007>
Category
I
II

Date
identified-

Name

Description-

Workers discovered water seeping from hairline cracks in seams in a
concrete wall near the elevator in a restricted area on the 2nd floor of
Water leak in
the reactor building. The volume of water was approximately 6.5
liters, and the measured radioactivity was 250 Bq. Further seepage
restricted area ofIII
20 Oct 07
No. 7 reactor
was discovered from seams in the concrete floor on the 3rd floor on
building
October 23. The volume was approximately 200 cm3 and themeasured radioactivity was 0.8 Bq. Neither case resulted inradioactive emission into the external environment.
2) Nonconformities (related to Chuetsu oki earthquake: As excluded)
11 - 23 October, 2007 (cumulative total since 16 July 2007)No.
49 (2,947)
3) Other- Internal inspection of No. 7 reactor: removal of fuel rods completed October 23- The No. 7 reactor control rod that could be removed (previously notified October 18) was successfully removed at approximately
11:37 a.m. on October 24 in accordance with the prescribed procedure for potential nonconformities. The cause of the difficulty inremoving the control rod will be investigated.
* Details of procedure
Control rods are normally inserted and removed via a powered process, with hydraulics used for emergency insertion (known
as a scram operation). The prescribed restoration procedure is designed for use in the event of nonconformities in the drive
mechanism.
After the standard powered removal operation was attempted on the recalcitrant control rod, the rods were all inserted using
the hydraulic scram operation, then removed using the standard removal operation.
- As part of the investigation into the water leaking into the No. 7 reactor well liner drain, we have checked the spent fuel pool andother large liquid tanks of all reactors and tested for radioactive substances. At the present point in time, we have not discovered
any significant water leaks (for instance, from the reactor well liner) other than in the No. 7 reactor.
Nevertheless, water seepage from other walls is clearly irrefutable in light of the continuing leakage of water into the liner drainof the No. 7 reactor, and the fact that sloshing of water during the earthquake caused water to leak onto the operating floors in
all reactors. As a result, continuing patrols will be necessary on an ongoing basis.
A very minor volume of seepage was detected in the wall of the spent fuel pool below the operating floor in the No. 1 reactor,
and was thought to be attributable to sloshing. Analysis found trace levels of radioactive substances. Monitoring is continuing.