At around 6:20 PM on July 20, 2012, a TEPCO employee on patrol found a fuel oil (gas oil) leakage from the diesel generator used for the spare nitrogen supply equipment (nitrogen gas separator on the hill) at Fukushima Daiichi Nuclear Power Station.

As the technical specification for the nuclear reactor facility^*1 requires the spare nitrogen supply equipment (including the diesel generator) to be operable, it was judged that the "operational requirements"^*2 stipulated in the technical specification for the nuclear reactor facility are not satisfied at 7:14 PM on the same day.

After the spare diesel generator was connected to the nitrogen supply equipment, operation check was done on the nitrogen supply equipment at 1:48 AM on July 21, 2012. Since no problem was found as a result, it has been judged that the equipment was recovered (the operational requirements were satisfied) at 2:29 AM.

We will continue our utmost efforts in maintaining the cold shutdown state and ensuring the safety of power station.

*1 Technical specification for the nuclear reactor facility
Government-approved fundamental rules for nuclear power station operators to follow in order to maintain safe operation and stable condition of nuclear power stations (including operation management, fuel management, radiation management, emergency measures and equipment/facility management based on the "Policy on the Mid-term Security"), which are stipulated by Article 37 Section 1 of the Act on the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors.

*2 Operational requirements
In accordance with the technical specification for the nuclear reactor facility, operational requirements are stipulated to ensure safety and stability of power stations (such as the number of available equipments, temperatures and pressures). In the case that an issue arises with equipment subject to the technical specification and the operational requirements cannot be satisfied temporarily, the required measures must be implemented.