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Information of Kashiwazaki-Kariwa Nuclear Power Station (The 4th news)
1. On-site investigation by JANTIThe Japan Nuclear Technology Institute (JANTI) dispatched three staff members
to the Kashiwazaki-Kariwa Nuclear Power Plant on July 23 and 24 to investigate
the on-site status of the power station and its surrounding areas (the surrounding
areas on July 23 and the power station itself on July 24). The following are themain findings of the investigation. The reactor and turbine buildings appeared tohave maintained a sound state in our visual check. We have confirmed thatreactors are in the state of shutdown safely.
(1) Situations at the power planta. Of seven reactor units installed, three units were in operation (Units 3, 4 and7), one unit was undergoing the process of start-up (Unit 2), and the remaining
three units were in outage shutdown (Units 1,5 and 6) when the earthquake
struck.
b. The reactors in operation or under the startup process automatically scram as
designed with no problems, in response to the signal indicating “Large”
seismic acceleration.
c. The automatic scram was followed on with the cold shutdown procedure, asstipulated in the manual.Currently, all seven reactor units, including those inoutage shutdown, remain safely in the state of cold shutdown in accordancewith the Safety Regulations.At all units, the instruments for gauging the levelof radiation in reactor water and at exhaust stacks showed no irregularreadings, indicating that there is no damage to nuclear fuels.The minuteleakage of radioactive materials, reported at Unit 6 and Unit 7, has sincestopped.
d. The reactor and turbine buildings, designed with an advanced level ofearthquake resistance, appeared to have maintained a sound state in our visualcheck (See Picture 1, Picture 2, Picture 3, and Picture 4.). Facilities andstructures with a relatively low level of earthquake resistance showed partial
damage.Tokyo Electric Power Company is carefully examining the conditionof each of the damaged sections one by one right now.
e. The following are main situations confirmed in this investigation:<Fire at the house transformer of Unit 3>- The earthquake caused a fire at the house transformer of Unit 3.The stationtransformer, installed beside the turbine building, supplies electricity,generated at the unit, to equipment on the same premises.
- The base of the transformer’s main unit is staked down to the rockfoundation, and the turbine building on the supply side is also affixed to therock bed.However, the support structure for the secondary connecting bus
duct linking the two facilities did not have rock-bed reinforcement.There is apossibility that when the quake caused the ground underneath the support
structure to sink (by approx. 30 centimeters), the conductor came in contact
with the duct, triggering a short circuit and igniting leaked oil (See Picture5.).
- The transformer is currently unusable.However, a separate startup
transformer is being used to supply enough electricity to secure plant safety(See Picture 6.).
<Damage to the piping of the fire protection system at Unit 1>- The earthquake caused damage to the piping of the fire protection system,
installed outside the reactor combination building for Unit 1.Water, leaked
from the piping, became combined with soil and sand, and seeped into thecomposite reactor building through the gaps in the piping housing.This left apool of mud water, approximately 48 centimeters deep, on the fifth basementof the reactor combination building (See Picture 7 and Picture 8).
-The basement floors of the reactor combination building house numerous
devices associated with waste processing.However, unlike the basement of
the reactor building, it does not contain important equipment in terms ofreactor safety, such as pumps for the emergency core cooling system and soon.
- This piping for the fire protection system has been repaired, with no morewater leakage.Work is underway to drain out the accumulated pool of water.
<Release of radioactive materials into the seawater at Unit 6>- The jolts from the earthquake upset the water in the spent fuel storage poolsof all reactor units, and overflowed onto the reactor buildings’ operating
floors (See Picture 9.).
- Of these cases, the flooded water at Unit 6 dripped through the gaps at thefloor joins of a duct for passing through fuel exchanger’s electrical cables,
traveled through the cable duct, and reached non-controlled areas (SeePicture 10.).
- Since seepage in non-controlled areas is normally uncontaminated withradiation, it is designed to be released to the outside environment with thestorm drain system.The leaked water in this event was also channeledthrough this route, and pumped out into the sea.
- All overflow water from the spent fuel storage pool has been processed.On
the day of the investigation, TEPCO was conducting a check on the airtightness of the floor joins of the cable duct.
(2) Situations in the surrounding areasa. Conditions of roads and ports
National Route No.8, a trunk road linking Nagaoka and Kashiwazaki cities,
was closed after some sections collapsed in the earthquake, but was reopened
for traffic on July 23 after round-the-clock restoration work.Many roads
reported sinkage and the development of gaps at the approach to bridges andother structures, but swift restoration work has been conducted to minimize
inconvenience to road users (See Picture 11 and Picture 12.).No particulardamage was observed at port facilities.
b. Conditions of residential buildings
Houses that collapsed were mostly old, wooden structures with tiled roofs.This
inspection found concentration of damage in the township of Nishi-Honcho.As
of July 23, a total of 961 houses were reportedly destroyed in the quake (SeePicture 13.).
c. Other situations
While power supply has been restored, it appears the recovery of watersupplies to the affected areas will take some more time, as indicated by the
number of water trucks servicing the communities.A large number of SDF
troops have been mobilized to engage in restoration work (See Picture 14 andPicture 15.).
(3) Inspection staff’s comments
The roof collapsed extensively at the power station’s administration building,making it impossible to perform work there.Part of the emergency response officeand meeting rooms have been set aside so that staff can identify the extent ofdamage and issue instructions on countermeasures (See Picture 16.).
The door to the emergency response office, set up in the administration building,
was initially jammed, denying access to workers who tried to use the emergency
phones there that had direct connections to the local government and local fire
department.The suspension of water supplies means that most toilet facilities,
with some exceptions, remain unavailable.These experiences provide a valuablelesson in formulating response to future emergencies.
Although it is expected to take a substantial amount of time to fully restore thepower station, the morale of station workers appeared very high.JANTI staff felt
their eagerness in wanting us to distribute correct information accurately and in atimely fashion to overseas and the rest of the Japanese population.
JANTI will continue to examine and investigate the status of the power stationfrom a third-party standpoint, and release relevant findings to external parties.
2. Other information(1) As of July 24, the power station newly identified damage to the shaft joint thatdrives the overhead crane in the reactor building of Unit 6.According to
TEPCO, the main unit of the crane is supported by railings on both sides, anddoes not fall even if the shaft suffers damage.
(2) Thus far, TEPCO has identified approximately 70 locations that suffered quake
damage, and will continue with a detailed investigation.

Information contained in this report will be updated as future detailedinvestigations by TEPCO make new findings.
＜References＞ Tokyo Electric Power Company
Nuclear and Industrial Safety Agency
Nuclear Safety Commission of Japan

Japan Nuclear Technology Institute
Rev.1
July 27, 2007

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