Press Releases 2013

In response to the accident at the Fukushima Daiichi Nuclear Power Station due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake which occurred on March 2011, TEPCO has four gas turbine power supply cars^*1 in total, two at Fukushima Daini Nuclear Power Station and two at Kashiwazaki-Kariwa Nuclear Power Station.

On May 15 and 16, 2013, we received reports from the manufacturer of the gas turbine power supply cars that these four cars include three cars each having a device (ignition plug exciter)^*2 that contains a radioisotope (Krypton-85) subject to the Act concerning Prevention of Radiation Hazards due to Radioisotopes, etc^*3. These three cars are the two at Fukushima Daini Nuclear Power Station and one at Kashiwazaki-Kariwa Nuclear Power Station.

We were not informed of the radioisotope contained in these three gas turbine power supply cars when we set these cars in place.

Today, we have reported this incident to Nuclear Regulatory Agency, and have requested the manufacturer to replace these devices as soon as possible with those that satisfy the regulatory values according to the Act.

Immediately after receiving the reports from the manufacturer, TEPCO measured radiation doses in the surroundings of the devices in the gas turbine power supply cars, thereby confirming that the radiation doses were at the same levels (the background levels) as those in the surrounding environments and that the radioisotope would not affect the surrounding environments. Also by yesterday, through implementation of stricter management of the keys for the gas turbine power supply cars, we took a measure to prevent loss of the radioisotope. In addition, indications for promoting awareness were put on the gas turbine power supply cars.

*1) gas turbine power supply car:
So that an alternative facility can be available in addition to a regularly-operated facility for the purpose of further bolstering the heat removal and cooling capabilities, a gas turbine power supply car is set in place as a power supply that enables operation of necessary loads such as a residual heat removal system pump even in a case when all the AC power supplies have been lost.

*2) device (ignition plug exciter):
This is an electronic device part that applies a high voltage to an ignition plug inserted into a gas turbine combustor and causes the ignition plug to spark. This operates only at the time of ignition at the start-up. This device has a small amount of Krypton-85 sealed up inside a gap tube for the purpose of stable discharge and life extension of the ignition plug exciter. Note that Krypton-85 has been kept in a gaseous state and sealed up in an airtight container.

*3) the Act concerning Prevention of Radiation Hazards due to Radioisotopes, etc.:
A radioisotope is subject to the Act when the amount of radioactivity of the radioisotope exceeds10 KBq/unit. In this case, the amount of radioactivity exceeds 10 KBq/unit (car) for each of the three gas turbine power supply cars. Therefore, these three cars have the radioisotope subject to the Act.