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).
Therefore, we have confirmed that flooding the 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 submitted the
report to NISA today.
(Already announced on April 30th, May 5th,2011)
We hereby notify that we have received the instruction*2 "Implementation
of a measure to flood the primary containment vessel to the upper area of
fuel range in Unit 1 of Fukushima Daiichi Nuclear Power Station" on May
5th, 2011.
In compliance with the implementation instructions from NISA, and ensuring
safety, we will steadily implement "A measure to flood the primary
containment vessel to the upper area of the fuel range in Unit 1 of
Fukushima Daiichi Nuclear Power Station".
Attachment:
Report regarding the implementation of a measure to flood the primary
containment vessel to the upper area of fuel range in Unit 1 of Fukushima
Daiichi Nuclear Power Station (summary)(PDF 149KB)
*1 Instruction notice regarding report
Submission of the report regarding the implementation of a measure to
flood the primary containment vessel to the upper area of the 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 a timely
manner based on article 67, clause 1 of the 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 following day when the instruction was acknowledged.
However, it is not entitled to do so after one year from the following day
of the instruction even if within 60 days from the following day when it
acknowledges the instruction.
After the treatment of a formal objection is determined, action to rescind
the disposition can be made against the government (representative:
ministry of law) based on Administrative Case Litigation Act (law number
139, 1962) within 6 months 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 following day when it acknowledges the
determination.
In case of the followings, TEPCO is entitled to take action to rescind the
disposition without the determination of a treatment of a formal objection.
1: treatment is not determined within 3-months from the following day when
a formal objection is made. 2.there is an urgent need to avoid significant
damage caused by disposal, execution of disposal and continuation of
execution. 3.there are justifiable grounds for not having the
determination of treatment.
Submission of report regarding the effect to stable reactor cooling and
the safety of a measure to flood the primary containment vessel to the
upper area of the fuel range in Unit 1 of Fukushima Daiichi Nuclear Power
Station.
1.impact on the structural strength and earthquake resistance qualities of
the reactor building and primary containment vessel from the water level
increase in the primary containment vessel
* Result of the impact analysis on the structural strength of the
structure and facilities in the primary containment vessel including the
reactor building, dry well, and suppression chamber from the water level
increase in the primary containment vessel
* Result of evaluation regarding whether the reactor building and
structure and facilities in the primary containment vessel can sustain
the designed seismic force.
2.Impact from the pressure increase inside the primary containment vessel.
* Estimation of the pressure increase inside the primary containment
vessel from the water level increase
* Result of the analysis on the necessity of a countermeasure to reduce
the pressure inside the primary containment vessel in consideration of
the above estimation.
3.impact from the increase of leaking water in the turbine building
* Estimation of the amount of leaking water at present and in the future
and the possibility of leakage to the outside environment.
4.Other issues relating to the safety evaluation regarding the
implementation of a measure to flood the primary containment vessel to
the upper area of the fuel range.
*2 Instruction notice regarding implementation
Implementation of a measure to flood the primary containment vessel to the
upper area of fuel range in Unit 1 of Fukushima Daiichi Nuclear Power
Station
NISA no.1, 2011.5.5
On April 30th, 2011, we instructed TEPCO to report the implementation of a
measure to flood the primary containment vessel to the upper area of the
fuel range in Unit 1 of Fukushima Daiichi Nuclear Power Station based on
article 67, clause 1 of Act on the Regulation of Nuclear Source Material,
Nuclear Fuel Material and Reactors.
Today, we have received a report and examined its contents. As a result,
NISA has evaluated the measures as appropriate since there was no other
effective option under such a dangerous circumstance. When implementing,
we would like TEPCO to follow the instructions below with absolute
accuracy to secure sufficient degree of safety.
1.Implement sufficient monitoring for the water level inside and leaking
water from the primary containment vessel. In addition, in an
appropriate manner, implement the countermeasures previously planned
such as controlling the amount of water being injected.
2.Examine the seismic reinforcements to the already strained supporting
posts of the suppression chamber with improvements to the working
environment, since the continued occurrence of aftershocks is to be
expected.