Fukushima Daiichi NPS Prompt Report 2013

This is follow-up information on the activation of "the bus voltage low alarm" and the suspension of the on-site power supply facilities (3B) at Fukushima Daiichi NPS, which was found at around 9:47 AM today (on October 7).

As the reactor water injection pump (B) of the condensate storage tank (CST) for Unit 1 was suspended, the reactor water injection pump (A) of the condensate storage tank (CST) was immediately automatically activated, but there was a temporal change in the amount of the reactor water injection.

<The amount of the reactor water injection for Unit 1 (the total flow rate)>
- It is stable as follows:
4.6m³/h → 0.6m³/h → 4.6m³/h
(The necessary amount of reactor water injection: 2.3m³/h)

Therefore, at 10:25 AM on the same day (on October 7), we determined that Unit 1 cannot meet the regulation "to secure plenty of reactor water injection necessary for cooling reactors" as per Article 18 fixing the operational regulation on the reactor water injection system in security measures concerning the operational safety of the specified nuclear reactor facilities for power generation, Unit 1 to 4, the implementation plan concerning specified nuclear reactor facilities for power generation at Fukushima Daiichi NPS. However, at the same time at 10:25 AM, we determined that Unit 1 is beyond the deviation from the regulation of operation, based on the stable amount of the reactor water injection.

Currently, the flow rate of the reactor water injection for Unit 1 is stable at 4.6m³/h and no significant change in the related parameters is found.

And we would like to correct an error as follows, regarding information mentioned the previous issue on this matter.
Wrong: The primary containment vessel gas control for Unit 1 to 3 is in operation. (No influence)
Right: When the on-site power supply facilities were suspended, the exhaust fan (B) was suspended, and the exhaust fan (A) is automatically in operation.

This has no influence on the monitoring of the primary containment vessel gas control system.