Post-quake status of the Kashiwazaki-Kariwa Nuclear Power Station (Report #10)
- Update on the overall situation through to October 5 October 9, 2007
Rev.0
Japan Nuclear Technology Institute
The Report #10 summarizes the post-quake status of the Kashiwazaki-Kariwa Nuclear Power Station andgives the overview of the initiatives, trends and other details involving Tokyo Electric Power Company andother relevant organizations.

1.Status of main inspection and restoration work
(1)Overall status
Currently, detailed equipment inspection and restoration work is systematically underway at theKashiwazaki-Kariwa Nuclear Power Station. TEPCO is to summarize and release inspection results assoon as they are available.
See the attachment for the overall status of main inspection and restoration work.
(2)In-core inspection
a.Overall inspection schedule (plan): Excerpt from TEPCO press release issued on September 6

b.Status of in-core inspection at Unit 1<Phase 1 (Inspection of the upper reactor)>
The inspection of the upper reactor was conducted from August 21 to 23, and identified no damage,disfigurement or dislodgment.
<Phase 2 (Inspection of the mid reactor --- the reactor core)>
The inspection of the mid reactor was conducted from September 14 to October 1, and identified thefollowing:･ No damage, disfigurement and dislodgement were found in the upper reactor (apart from sections
checked in Phase 1), mid reactor and steam dryer that had been dismounted for outage andtemporarily stored in the temporary storage pool.
･ As for the steam separator, which had been also dismounted for outage and temporarily stored in
the temporary storage pool, the inspection found disfigurement on the temporary legs for storage(4 out of 4) and guide pins (2 out of 2 pins), used to position the unit properly in the reactor. Thelegs and guide pins are auxiliary parts of the steam separator, and do not affect its functions orstructure.
(*) The identical legs for temporary storage were also bent at the Onagawa Nuclear Power
Station of Tohoku Electric Power Company and TEPCO’s Fukushima Daiichi Nuclear
Power Station at the time of the Miyagi offshore earthquake in May 2003. Similar
damage was also reported at the Shika Nuclear Power Station of Hokuriku Electric Power
Company at the time of the Noto Peninsula earthquake in March 2007.
･ The disfigurement of the steam separator’s temporary legs also caused scratches on the floor of
the temporary storage pool, but no water leakage was identified from the location.
<Phase 3 (Inspection of the bottom of the reactor)>
Inspection preparation commenced on October 2.
d.Status of preparation work at Unit 7
Reactor opening work takes place from October 2 to 8, to be followed by Phase 1 and Phase 2
inspections.

2.Status of non-conformity management (associated with the Niigataken Chuetsu-okiEarthquake )TEPCO defines the management status of non-conformities at power stations into six grades (As – Notapplicable) and regularly releases the information. The screening status of non-conformities as of
September 26 is as follows. There are 2,850 earthquake-related non-conformities, and most of them areclassified as minor events of Grade C or below.
No. of non-conformities
SeptembJuly
Auguster 1 – 26GradeDescription

As

Reportable event as stipulated by lawor Safety Regulations (events thathave a serious impact on plant
performance and safety)

1000A

Seriousnon-conformity againstquality
assurance
requirements(events that have a serious impact onoutage schedule) etc.

33

1028

50562277

46841

932

109

B

C
D

Non-conformity pointed out in agovernment inspection (events that
requireenhanced
operation
monitoring, etc.)
Minor non-conformity against quality
assurance requirements, etc.
Event within the scope of normal
maintenance, etc.

Remarks･Flooding of the operating
floors･ Fire of the in-housetransformer at Unit 3, etc.
･ Displacement of the ductconnecting to the main
exhaust stack･Damage to fire protection
system’s piping, etc.
･ Dislodgment of a blwout
panel, etc.

N/AReplacement of a consumable andequivalent event, etc.
Total

411

1,478

1,216

156

(Note)Examples of Grade C events include “leakage from the mechanical seal of a pump” and “damage topassageway windowpanes” (events concerning human safety), while examples of Grade D events include“valve seat pass that can be addressed with increased tightening”.

3.Geological survey
TEPCO has decided to expand the scope of geological survey to cover land areas around theKashiwazaki-Kariwa Nuclear Power Station, adding underground prospecting to marine sonic prospecting.
The next survey will conduct underground prospecting on land areas near the power station as well as theland area that includes the Seiryoku fault belt in the Nagaoka Plain, so as to assess underground structures toconfirm / evaluate the group of active faults in the region.
On the station premises, a boring investigation will be conducted to confirm / assess the structure ofunderground areas underneath the plant. Samples will also be collected to check the post-quake propertiesof the sub-grade to determine the possibility of land subsidence and liquefaction.

4.Moves by electric utilities
In an effort separate from the seismic safety assessment, electric utilities have compared the seismic
records of the earthquake’s main shock, observed on the foundation level of reactor buildings at theKashiwazaki-Kariwa Nuclear Power Station, against the benchmark seismic motion used when designing a
nuclear power station, so as to examine the earthquake’s impact on important station facilities that serve thefunctions of “shutting down”, “cooling down” and “containing”.
On September 20, the companies compiled and submitted a report to the Ministry of Economy, Trade andIndustry, concluding that the safety functions of their key facilities, serving the functions of “shutting down”,“cooling down” and “containing”, will be maintained under a similar earthquake.
In regard to this report, the Nuclear and Industrial Safety Agency expressed its opinion that theassessment covered main facilities that serve such functions that count in terms of plant safety, and that thesafety functions of these facilities were assessed appropriately.

5.Initiatives and trends of relevant organizations(1)METI (Nuclear and Industrial Safety Agency)
a.Examination at the investigation committee regarding nuclear facilities affected by the Niigataken
Chuetsu-oki Earthquake
This committee was set up to undertake an investigation into the specific impact of the Niigataken
Chuetsu-oki Earthquake on the power station, and to explore future tasks and actions to be taken by
the government and nuclear energy companies in light of this earthquake.
Working groups under this committee will examine the following specific issues and submit thefindings to the committee for deliberation. The committee convened its third meeting on September
12.
<Working Group on in-house fire fighting corps and liaison / provision of information in relation to theNiigataken Chuetsu-oki Earthquake >･ In-house fire fighting corps system･ Information liaison system for plant operators･ Initial response & preparation system in emergency･ Information provision to local governments and the public<Subcommittee on anti-quake and structural designs>･ Using research data on this earthquake from relevant organizations, observation data of seismic

motions and study data used in designing the plant to identify why the observed seismic motions
recorded in the earthquake on the foundation level of reactor buildings at the power station weregreater than their design figures･ Examining the earthquake’s impact on the Kashiwazaki-Kariwa Nuclear Power Station･ Examining items that should be reflected to the seismic safety assessment of theKashiwazaki-Kariwa Nuclear Power Station･ Summarizing the insight obtained from this earthquake and identifying items that should bereflected to other nuclear power stations from the perspective of ensuring seismic safety ofnuclear facilities<Working Group on nuclear plant administration, management and facility integrity assessment>･ Operation management immediately after an earthquake･ Assessment of facility integrity
b.Establishment of the Fire Management Office
In cooperation with the Fire and Disaster Management Agency, the Fire Management Office wasestablished within the Nuclear Emergency Planning Section to urgently compile effective measures forpreventing and controlling fires at nuclear power stations, and provide guidance on such measures toelectric utilities.
At the meeting of the “Working Group on in-house fire fighting corps and liaison / provision ofinformation” convened on September 20, the Fire Management Office presented the policy forreinforcing the in-house fire fighting system (software, hardware) to enhance its abilities for “makingimmediate response”, “controlling fire” and “sustaining fire fighting activities”.
(2)Nuclear Safety Commission
The expert committee on nuclear safety standards has set up the “Fire Prevention and Management
Subcommittee” to examine the current fire protection system at the time of earthquake, including a review
on the fire protection guidelines. (First meeting: September 25)(3)International Atomic Energy Agency (IAEA)
On August 18, the International Atomic Energy Agency (IAEA) released a report on the inspection
carried out by its fact-finding mission from August 6 to 10. The outlines of the report are as follows:<Outlines of the report by the IAEA fact-finding mission>a.The operating plants were automatically shutdown and all plants behaved in a safe manner, during
and after the earthquake. The three fundamental safety functions (shutting down, cooling downand containing) were ensured.
b.The radioactive releases to the environment were very minor and estimated to result in anindividual dose well below the authorized limits.
c.Safety related structures, systems and components of the plant seem to be in a general condition
much better than expected for such a strong earthquake, with no visible damage. This isprobably due to the conservatisms introduced at different stages of the design process.
d.Any re-evaluation of the seismic safety of the plant in accordance with the new seismic guidelines
needs to be done taking into account the effects of this earthquake, and the issue of the potential
existence of active faults underneath the site.
e.Another consideration is the possibility that a component remains functionally available undernormal operating conditions but sustains hidden damage.
(4)Moves by related academic societies
On September 11, an emergency forum “Niigataken Chuetsu-oki Earthquake --- What happened at
the Kashiwazaki-Kariwa Nuclear Power Station” was convened as part of the 2007 annual conference of

the Japan Society of Mechanical Engineers. TEPCO explained the outline of the earthquake as well as
the quake’s impact on plant management and facility integrity, which was followed on with an active
Q&A session.
On September 28, the Atomic Energy Society of Japan conducted a briefing on the Niigataken
Chuetsu-oki Earthquake and the safety of the Kashiwazaki-Kariwa Nuclear Power Station as part of its
annual autumn conference for 2007. In various presentations, the following notable opinions wereexpressed as the “reasons the nuclear reactors maintained their safety functions despite being struck withtremors well above the design basis seismic motion”:
a.Reactor facilities are highly resilient because of requirements unrelated to anti-quake criteria (e.g.
nuclear containment, retention of internal pressure).
b.Conservative anti-quake mechanical designs are applied.
c.Shaking table tests, etc. suggest that the facilities’ actual seismic margin is greater by scores of times.

6.Initiatives by JANTI
Main activities by JANTI, conducted after Report #6 issued on August 10, include visiting relevant
overseas organizations for briefing (See Reports #7 and #9), and establishing the Reactor Equipment
Integrity Assessment Committee (chairman: Toshiharu Nomoto, professor emeritus of the University ofTokyo) within JANTI to assess and examine the integrity of the power station’s key equipment, which wassubject to tremors above the design-basis seismic motion.
On September 26, the Committee convened the first meeting, attended by around 60 people including
experts of structural strength, inspections and quake resilience, as well as relevant parties representing
electric utilities and plant manufacturers. The Committee plans to meet once every month through to theend of this fiscal year.
<Description of content>① Examining the approach and method of integrity assessment for equipment exposed to seismic load
② Assessing quake damage of individual equipment, and conducting analysis to evaluate the integrityof equipment / parts. Also conducting precautionary assessment on the tolerance level of thecurrent anti-quake design
END