On April 30th, 2011, we received the instruction "Submission of report 
regarding the implementation of a measure to flood primary containment 
vessel to the upper area of fuel range in Unit 1 of Fukushima Daiichi 
Nuclear Power Station" from Nuclear and Industrial Safety Agency (NISA).
                                (Already announced on April 30th, 2011)

Thereafter, we have confirmed that flooding primary containment vessel 
to the upper area of fuel range in Unit 1 of Fukushima Daiichi Nuclear 
Power Station will have stable cooling effect on the reactor and that 
there will be no problematic issues regarding safety. We notify here 
that we submitted the report to NISA today.

                                                                   End

Attachment:
Report regarding the implementation of a measure to flood primary
containment vessel to the upper area of fuel range in Unit 1 of
Fukushima Daiichi Nuclear Power Station (summary)(PDF 149KB)

*Instruction Notice
Submission of report regarding the implementation of a measure to flood 
primary containment vessel to the upper area of fuel range in Unit 1 of 
Fukushima Daiichi Nuclear Power Station

                                                   NISA no.1, 2011.4.30

NISA hereby instructs TEPCO to report the following matters in timely 
manner based on article 67, clause 1 of Act on the Regulation of Nuclear 
Source Material, Nuclear Fuel Material and Reactors in order to evaluate 
the appropriateness of an emergency measure planned by TEPCO.

In case TEPCO disagrees with this instruction, it is entitled to make a 
formal objection in writing to the minister of economy, trade, and 
industry based on Administrative Appeal Act (law number 160, 1962) 
within 60 days from the next day when it recognizes the instruction. 
However, it is not entitled to do so after one year from the next day of 
the instruction even if within 60 days from the next day when it 
recognizes the instruction.

After the treatment of a formal objection is determined, action for 
rescission of a disposition can be made against the government 
(representative: ministry of law) based on Administrative Case Litigation 
Act (law number 139, 1962) within 6 month from the next day when it 
recognizes the determination of treatment of a formal objection. However, 
it is not entitled to do so after one year from the next day of the 
determination even if within 6 months from the next day when it recognizes 
the determination.

In case of the followings, TEPCO is entitled to make action for rescission 
of a disposition without the determination of treatment of a formal 
objection. 1: treatment is not determined within 3 month from the next day 
when a formal objection is made. 2. there is urgent need to avoid 
significant damage caused by disposal, execution of disposal and 
continuation of execution. 3. there is a justifiable ground for not having 
determination of treatment. 

Submission of report regarding the effect to stable reactor cooling and 
safety of a measure to flood primary containment vessel to the upper area 
of fuel range in Unit 1 of Fukushima Daiichi Nuclear Power Station.

1.impact on structural strength and earthquake resistance of reactor 
  building and primary containment vessel from the water level increase 
  in primary containment vessel
  * Result of impact analysis on the structural strength of structure and 
    facilities in primary containment vessel including reactor building, 
    dry well, and suppression chamber from the water level increase in 
    primary containment vessel
  * Result of evaluation whether reactor building and structure and 
    facilities in primary containment vessel can sustain the designed 
    seismic force. 
2.impact from the pressure increase inside primary containment vessel.
  * Estimation of the pressure increase inside primary containment 
    vessel from the water level increase
  * Result of the analysis on the necessity of countermeasure to reduce 
    the pressure inside primary containment vessel considering the above 
    estimation. 
3.impact from the increase of leaking water in turbine building
  * Estimation of amount of leaking water at present and in the future 
    and possibility of leakage to outside environment.
4.Other issues relating to safety evaluation regarding the implementation 
  of a measure to flood primary containment vessel to the upper area of 
  fuel range.