NISA instruction to TEPCO

NISA, or for those who are recently joined readers, the Nuclear and Industrial Safety Agency, has instructed TEPCO (Tokyo Electric Power Company) to make a very thorough analysis of various parameters relative to TEPCO's plan to flood the dry well of Fukushima Daiichi No. 1 to a level above that of the active fuel region inside the pressure vessel.

It is beginning to look as if NISA seriously questions this move... not in terms of restoration of core cooling, but rather in terms of building safety and more importantly (and directly) reactor safety in the event of a further earthquake, taking into consideration the large increase in mass that this much water will add to the dry well structure.

This is perhaps one of those watershed moments, because if TEPCO finds that this plan is not safe in this seismic environment (or if NISA doesn't like TEPCO's answer and stops the plan anyway) then this will entirely derail TEPCO's sole plan to restore core cooling in a timely manner.

Here is the content of the NISA letter to TEPCO, dated April 30, 2011.

*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
April 30, 2011

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.

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We can be sure TEPCO will produce a report practically immediately because there is a real need to determine another plan should filling the dry well be cancelled. This writer is of the mind that ongoing discussions about this water mass in the plant were probably why TEPCO backed water feed off to 6 cubic meters / hour when prior to this the cooldown had been very successful at higher rates (over double the present rate.)

This is a pivotal report for the movement of plant recovery forward, so we will be watching for the response and have it up here as soon as we see it.

3:45 PM Eastern Saturday 4/30
ATOMIC POWER REVIEW