The Tokyo Electric Power Company, Inc. is conducting field investigations at 
the Kashiwazaki-Kariwa Nuclear Power Station since the Niigata-Chuetsu-Oki 
Earthquake occurred on July 16, 2007. Today, we submitted reports regarding 
the following items to the Minister of Economy, Trade and Industry in 
accordance with "Article 19-17, Rules on the Installation, Operation and 
Others of Commercial Power Rectors".

The possible causes and preliminary measures as of today for each incident 
in the reports are as follows:

1. Leakage of water containing radioactive materials into the non-controlled 
   areas in the Unit 6 reactor building

 [Outline of the Event] 
  It was confirmed that on July 16, 2007, 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 of the 
  spent fuel pool into the mezzanine floor (non-controlled area) between 
  the second and third floors through a electrical wire conduit tube connected 
  to the power supply box of the refueling machine, and then run down into 
  the third floor (non-controlled area) and into the non-radioactive drainage 
  collecting tank on the first basement (non-controlled area), and had been 
  finally released into the sea through the discharge outlet. The amount of 
  water released and its radioactivity was estimated to be about 1.2m3 and 
  about 9 * 104 becquerels, respectively.

 [Possible Causes] 
  Based on the results of our investigations, we estimated the cause of the 
  leakage of water containing radioactive materials into the non-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 by either 
     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 the mezzanine 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 the third floor into 
  the non-radioactive drainage collecting tank placed on the first basement, 
  and subsequently had been released by the drain 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 the radioactive 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 automatically start. 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 to improve 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 water that 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)
   - Unit 5 (Approx. 1.9 * 101 bq/cm3)
   - Unit 6 (Approx. 1.4 * 101 bq/cm3)
   - Unit 7 (Approx. 2.7 * 101 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 respectivespent 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 and decontaminated 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 Event] 
   After the Niigata-Chuetsu-Oki earthquake occurred on July 16, 2007, during 
   equipment inspection conducted on July 24, damages were confirmed 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; totalling 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.