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Information of Kashiwazaki-Kariwa Nuclear Power Station (The 6th news)- Update on the Overall Situation through to August 10 This Report #6 summarizes the post-quake status of the Kashiwazaki Kariwa
Nuclear Power Station and gives the overview of initiatives, trends and other details
involving Tokyo Electric Power Company and other relevant organizations.
1. Information on the earthquake (main shock)(1)Date and time: 10:13 on Monday, July 16, 2007 (local time)(2)Hypocenter: Approximately 17km deep off the Upper Chuetsu region of Niigata
Prefecture (The epicentral and hypocentral distance to the power station is 16km
and 23km respectively.)(3)Scale of the earthquake: 6.8 on the Richter scale (measuring the maximum 6+ on
the Japanese intensity scale in Nagaoka City, Kashiwazaki City and Kariwa
Village in Niigata Prefecture and some parts of Nagano Prefecture)
2. Post-quake status of the power station(1)Operation status
The earthquake correctly triggered the safety protection circuit, automaticallyshutting down Units 2 – 4 and Unit 7.The remaining Units 1, 5 and 6 had been
shut down for outage.
Currently, all plants are shut down in a stable state, with no significant fluctuations
in real-time data from the radiation monitors on main exhaust stacks and othermonitoring posts, indicating no radiation-related impact on the surrounding
environment.
(2)Seismic observation records at the power station
a.The table below shows the observation figures recorded on the lowest floor ofeach Unit’s reactor building (See Attachment 1), and design values for the same
locations.The east-west component at Unit 1 registered the maximum
acceleration of 680 gal.At Unit 2, the maximum acceleration recorded for the
east-west component (observation figure: 606 gal) was 3.6 times the value
anticipated in the design stage (design value: 167 gal).
(Unit: Gal)
Observation figures recorded on
Design values for the samethe lowest floor of the reactor
locationbuilding
Observation
location
NorthNorthEast-west Up-down
East-west Up-down
south
south
component component
component component
component
componen
Unit 1
311
680
408
274
273
(235)
Unit 2
304
606
282
167
167
(235)
Unit 3
308
384
311
192
193
(235)
Unit 4
310
492
337
193
194
(235)
Unit 5
277
442
205
249
254
(235)
Unit 6
271
322
488
263
263
(235)
Unit 7
267
356
355
263
263
(235)
(Note)The up-down component figures in brackets are used in static design.
b.TEPCO analyzed seismic observation data obtained during the main shock of therecent earthquake, compiled the findings thus far into a report (Report #1) andsubmitted it to the Nuclear and Industrial Safety Agency on July 30.The content
of the report was also publicly released.
<Released observation records>>> The “acceleration time-history waveform” obtained during the main shockon the lowest floor of the reactor buildings at Units 1 to 7, and “maximum
observed acceleration and maximum design acceleration response”>>

The comparison between the “floor response spectrum based on
observation records” observed on the lowest floor of the reactor buildings
at Units 1 to 7 and “floor response spectrum calculated based on thestandard seismic motion in the seismic response analysis model used in thedesign stage”
c.TEPCO will conduct seismic response analysis and anti-quake safety assessment
on key facilities in terms of safety, based on the level seismic motion that would
ensure safety against the intensity of the recent earthquake.It also plans to
explore items to be reflected to future anti-quake safety assessment and antiquake measures based on new knowledge obtained from this earthquake,
including findings from active fault probes in sea areas and analysis of seismic
observation data.
(3)Extent of damage at the power station
a. Main events confirmed in post-quake visual checks and their current status(a)Overflow of water onto the reactor buildings’ operating floors(All units)>> Earthquake-induced sloshing caused an overflow of water containing
radioactive materials from the spent fuel storage pools onto the operating
floors of reactor buildings.
>> As of July 27, the water has been wiped away at all Units.
(b)Displacement of the ducts connected to the main exhaust stacks(Units 1 - 5)>> No significant changes have been observed in monitoring post readings
before and after the earthquake, with no confirmation of radiation influence
to the external environment.
>> The size of the displacement and radiation leakage is currently underinvestigation.
(c)Flooding with 2,000 cubic meters of water in the Reactor Combination
Building due to damage to the fire protection system’s piping (Unit 1)>> On the 5th basement floor of the Reactor Combination Building at Unit 1(radiologically controlled area), the entire floor was flooded with watermeasuring 48 centimeters deep.The amount of water is estimated to beapprox. 2,000 cubic meters, and a minute trace of radioactive materials was
detected from the collected sample (approx. 6 becquerel/cc).
>> The cause of the incident is believed to be quake-damage to the outdoor
piping of the fire protection system, which allowed water to enter into thebuilding.
>> The basement floors of the Reactor Combination Building houses
numerous devices associated with waste processing.However, unlike thebasement of the reactor building, it does not contain important equipment
in terms of reactor safety, such as pumps for the emergency core coolingsystem.
>> This piping for the fire protection system has been repaired, with no morewater leakage.Work is underway to drain out the accumulated pool ofwater.
(d)Fire at the station transformer(Unit 3)>> At 10:15, immediately after the earthquake, plant operators identified
smoke coming from the station transformer at Unit 3.The Fire Department
extinguished the fire at 12:10.
>> The site was subsequently examined, including a visual check, to confirm
the following:- There is a vertical displacement between the applicable transformer andits secondary connection bus.
- There is oil leakage from the bushing on the applicable transformer’s
secondary side.
- There are severe signs of burning at the connection duct to thetransformer’s secondary connection bus, with part of the bus having
melted or fractured.
>> This transformer is currently unusable.However, a separate startup
transformer is supplying enough electricity for maintaining plantsafety.The emergency diesel generators at Units 1 – 7 underwent a routine
manual startup test from July 25 to 27, and had their functional integrity
confirmed.
>> Further details are being investigated.
(e)Release of radiation-contaminated water into the sea (associated with (a))(Unit 6)>>

Puddles of water were found in non-radiologically controlled areas on the
3rd floor and mezzanine 3rd floor of the reactor building at Unit

6.Radiation measurement found that the water contained traces ofradioactive materials.
>> It was later found that this water was discharged into the sea via water
discharge outlet.The amount of water discharged is estimated to be approx.
1.2 cubic meters with the radioactivity of 9x104 becquerels.No significant
fluctuations are observed in the readings of the seawater monitor, and theamount of radiation released was within the legal limit, indicating that there
was no impact on the environment.
>> The investigation showed that the water may have reached the nonradiologically controlled areas in the following route:- Earthquake-induced sloshing caused an overflow of water on theoperation floor on the 4th floor of the reactor building (radiologicallycontrolled area).The water then traveled into the power box of the fuelexchanger on the same floor, and dripped into a conduit tube from thegaps in the seal where the electrical cables in the box come through.
- The conduit tube is laid under the floor, and leads to non-radiologicallycontrolled areas of the reactor building.Some of the water that entered
the tube dripped from the upper air-conditioning duct onto themezzanine 3rd floor (between the 3rd and 4th floor) of the reactor
building, and traveled from floor openings on the mezzanine 3rd floor toreach the 3rd floor.
- The water that puddled on the 3rd floor drained into the floor scupper tobe gathered in the non-radioactive wastewater tank on the first basement
floor, before being pumped out into the sea.
>> As an immediate measure to prevent further discharge into the external
environment, the applicable tank’s pump has been shut down.The sealingmaterial for the power box of the fuel exchanger has also been replaced toprevent any gaps for higher air-tightness.
(f)Damage on the couplings of the drive axis for the overhead crane in thereactor building(Unit 6)>> Damage has been found on three of the four couplings.Detailed inspections
on other areas will also be continued.
>> The overhead crane has not become dislodged, and it has been confirmedthat there is no risk of the crane falling off the ceiling.(See Attachment 2)(g)Detection of iodine and radioactive particulate Matter by the monitor of themain exhaust stack(Unit 7)>> Regular measurement on the main exhaust stack at Unit 7 detected iodine
and radioactive particulate matter.The amount of radioactive leak from themain exhaust stack was approximately 4×108 becquerels.This puts theassessable radiation dose at approximately 2×10-7 millisieverts, which is
below the annual exposure dose limit for the general public, stipulated bylaw (1 millisievert).
>> The cause of the leakage is believed to be the delay in conducting a
shutdown operation for the turbine’s gland steam exhauster in theprocedure following the automatic shutdown of the reactor.It is suspectedthat the iodine and radioactive particulate matter, which remained residualin the condenser, were drawn into the turbine’s gland steam exhauster, andreleased into the atmosphere via the exhaust stack.
b.TEPCO defines the management status of non-conformities at power stations
into six grades (As – Not applicable) and regularly releases the information.The
status of non-conformities as of July 26 is as follows.There are over 1,200
earthquake-related non-conformities, and most of them are classified as minor
events of Grade or below.
No. of nonconformities
Grade
Description
Remarks
related to theearthquake
・Flooding of theReportable event as stipulated bylaw or Safety Regulations
operating floors
As (events that have a serious
10・Fire of the station
impact on plant performance andtransformer at Unit 3,
safety)etc.
A

Serious non-conformity against
quality assurance requirements

33

・Displacement of theduct connecting to themain exhaust stack(events that have a serious
impact on outage schedule) etc.

Damage to fire
protection system’s
piping, etc.

Non-conformity pointed out in a・Dislodgment of agovernment inspection (events
B
21
that require enhanced operation
blowout panel, etc.
monitoring, etc.)
Minor non-conformity against
C quality assurance requirements,
491
etc.
Event within the scope of normalD
706
maintenance, etc.
Replacement of a consumable
N/A
2and equivalent event, etc.
Total
1,263
（Note）Examples of Grade C events include “leakage from the mechanical sealof a pump” and “damage to passageway windowpanes” (events concerning
human safety), while examples of Grade D events include “valve seat pass thatcan be addressed with increased tightening”.
3. Initiatives and trends among relevant organizations(1)Ministry of Economy, Trade and Industry (Nuclear and Industrial Safety Agency)a.From the perspective of ensuring public safety and security, the Ministry
instructed electric utilities to implement the following measures on July 20:(a)Enhance the in-house fire-fighting system(b)Build a swift and strict accident reporting mechanism(c)Confirm facilities’ anti-quake safety with priority on public safety
b.On July 23, Director-General Komoda of the Nuclear and Industrial Safety
Agency visited Niigata Prefecture to explain the Agency’s handling of the issue
to the Governor of Niigata Prefecture, Mayor of Kashiwazaki City and theMayor of Kariwa Village, and exchanged opinions with them.
c.The Ministry has set up the Chuetsu Offshore Earthquake Investigation andCountermeasures Committee concerning Nuclear Power Facilities” toinvestigate facts regarding specific impact of the Chuetsu Offshore Earthquakeon the power station, and identify future tasks and responses the government andelectric utilities must address in reflection of the said Earthquake.
On July 31, the Committee convened its first meeting, and agreed to set up
Working Groups to examine specific issues listed below, and deliberate on theirfindings as the main Committee framework.
(a)The in-house fire-fighting corps, information liaison system and themechanism for distributing information to local communities in the event ofan earthquake(b)Anti-quake safety assessment based on the knowledge obtained from the
Chuetsu Offshore Earthquake(c)The status of reactor operation management at the time of the Chuetsu
Offshore Earthquake, integrity of plant facilities and future response
d.Local safety inspectors are currently examining the plant status, reported by
TEPCO, so as to identify the causes and detailed facts.
(2)Nuclear Safety Commission of Japana.On July 19, at an ad-hoc meeting of the Nuclear Safety Commission, Chairman
assured the safety of the Kashiwazaki Kariwa Nuclear Power Station inprinciple, based on the fact that the safety functions of greatest importance
operated correctly.He also expressed his views on faults / problems reported inthis earthquake, as well as future policies for addressing anti-quake safety.
b.On July 30, the Commission adopted the “NSC views on, and future actions totake for, the impacts due to the Niigata-ken Chuetsu-oki Earthquake”.The maincontents of the statement are as follows:<Effectiveness of the New Seismic Guide>
The necessity of revising again the New Seismic Guide should be judged
after the new Design Basis Earthquake Ground Motion be formulated in the
back-check process and verified against the actual impacts due to the
Earthquake. It is not the time to contend its necessity now.

<Confirmation of supporting capabilities of structures and systems>
The NSC requests that, in order to ensure conformance to the New Seismic
Guide, TEPCO confirm support performance of and provide necessary
reinforcement to the foundations for the structures classified as not only
Seismic Class S but also Class B and C at all existing nuclear power stations
as part of the back-check process.
<Strengthening of fire protection measures at earthquakes>
The NSC will investigate the status of compliance with the Fire Protection
guide to explore enhancements to fire protection measures, taking into
account the fact that the fire control systems did not function properly in theearthquake.
c.On August 7, Chairman Suzuki examined the latest status of investigation into
the earthquake’s impact on the Kashiwazaki Kariwa Nuclear Power Station, andvisited the Niigata Prefectural Government, Kashiwazaki City Council andKariwa Village Council to exchange opinions.
(3)Atomic Energy Commission
On August 7, the Atomic Energy Commission expressed its view on six key
issues, including appropriate dissemination of information, in regard to initiatives
already launched by the Nuclear Safety Commission and the Nuclear andIndustrial Safety Agency.
(4)Local governments (Niigata Prefecture, Kashiwazaki City, Kariwa Village)a.On July 18, Mayor Aida of Kashiwazaki City banned the use of the Kashiwazaki
Kariwa Nuclear Power Station in accordance with the Fire Protection Law,citing fire prevention issues.
b.The local authorities of Niigata Prefecture, Kashiwazaki City and Kariwa
Village conducted an “on-site inspection” according to Article 10 of the Safety
Agreement in order to examine the extent of damage to the power station andconfirm plant safety in the current status.The inspection was conducted on
August 1 and 2, accompanied by the members of the Niigata Prefecture’s
engineering committee on the safety management of nuclear power stations, so
as to utilize expert knowledge in investigating and checking the site.
(5)International Atomic Energy Agency（IAEA）
IAEA sent a fact-finding team to examine facts concerning radiation leakage andsafety operation management, and lessons to be learned from the experience, withfocus on areas of earthquake resistance.The team inspected the Kashiwazaki
Kariwa Nuclear Power Station and interviewed concerned parties on August 6 – 9,and exchanged opinions with the Nuclear and Industrial Safety Agency on August
10.
The findings of the investigation are expected to be released swiftly.
4. Initiatives by the Japan Nuclear Technology Institute
JANTI has compiled information on the status of the Kashiwazaki Kariwa Nuclear
Power Station since the Chuetsu Offshore Earthquake, mainly based on
information released by TEPCO, and provided accurate information in a timely
fashion both domestically and internationally as listed below:(1)Information delivery on the website (both in Japanese and English)
a.Status of the Kashiwazaki Kariwa Nuclear Power Station following theearthquake-Report #1 (July 18)Details of the earthquake and its impact on theenvironment-Report #2 (July 20)Information on seismic motions, remarks by the Chairmanof the Nuclear Safety Commission-Report #3 (July 23)News conference by METI Minister Amari, impact of theearthquake on nuclear fuel at the reactor core, etc.
-Report #4 (July 26)Report on the on-site investigation by JANTI-Report #5 (August 1)Results of analysis on seismic observation data (initialreport)（Note）Reports #1 and #2 were first posted on JANTI’s English website, as
accurate information was not reported overseas at the time.Japanese versions
have been postedfrom Report #3 onwards.

b.Status of the power station and main developments at TEPCO, national / local
governments
Posted on July 25 (and updated regularly since)(2)On-site investigation- July 23 – 24:On-site investigation (dispatching 3 officials to examine the extent
of damage at the power station, Kashiwazaki City and Kariwa Village)- The investigation findings were posted on the website as Report #4.
(3)Distribution of information to members- July 27
Engineering Seminar(at Sendai:Providing information to approx.
40 members in the Tohoku region as part of the report on JANTI
activities)- July 27
On-site investigation briefing (approx 20 people from Chubu
Electric Power Company)- July 31
On-site investigation briefing (approx. 40 people from otherelectric utilities, electrical industry manufacturers, and Japan
Atomic Industrial Forum)(4)Media relations- July 18
Yomiuri Newspaper:Interview article with JANTI President
Ishikawa- July 22
Hodo 2001:Featuring JANTI President Ishikawa- July 26
NHK News Watch 9:Quoting comments by JANTI Executive
Director- July 267
Mezamashi TV:Quoting comments by JANTI Executive Director- August 3
Regular meeting of the liaison council on the peaceful use of
nuclear energy:JANTI President Ishikawa describing the status of
the Kashiwazaki Kariwa Nuclear Power Station in his address tothe council- Other media engagements involving the JANTI President and other officials(5)Briefing overseas organizations
On August 24, JANTI will visit the U.S. Nuclear Energy Institute to provide abriefing on the status of the Kashiwazaki Kariwa Nuclear Power
Station.Coordination work is underway to arrange similar briefings for European
organizations.
Information contained in this report will be updated as future detailed
investigation by TEPCO makes new findings.
＜References＞ Tokyo Electric Power Company
Nuclear and Industrial Safety Agency
Nuclear Safety Commission of Japan

Japan Nuclear Technology Institute
Rev.0
August 1, 2007

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