APR: your source for nuclear news and analysis since April 16, 2010

Saturday, April 30, 2011

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.

-----------------------------------------------------

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

11 comments:

  1. wouldn't accepting higher earthquake risk in order to cool the reactors be a valid trade?

    I understand that NISA is trying to avoid blame, but it seems to me a quick albeit more risky resolution might be a better choice given the insistence of the govt to maintain an 20 km exclusion zone until; the reactors are cooled...

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  2. @jl: Not if, when there's another quake or large aftershock, the reactor building structurally fails and so does the primary containment along with it, which would be absolutely disastrous. NISA isn't avoiding blame, it's avoiding TEPCO taking highly increased risk (potentially) in order to secure a rapid cooldown.

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  3. ok, so this is concern about aftershocks, not another mag 9 quake...
    that makes more sense then...

    though, it raises the question of why this was not done prior to adding more water rather than waiting until they started....

    my background is in the aerospace field where we dont have the luxury of these prolonged failure modes, so I tend to view things as perhaps more urgent than they really are here.

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  4. could you suggest any nuclear engineering related books that would be good to learn more about fission reactors?

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  5. @jl: I have actually been thinking about working on an introductory level "required reading" list of such books. I will put together a list and post it here soon.

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  6. I am in the area and earthquakes, albeit smaller ones, are still happening and another vey big one is predicted. I have seen some of the damage up close, like in the town where I teach all the manholes are pushed up and out of the sidewalks like newly sprung meter-high mushrooms. That means all the pipes and tunnels below were shoved up a meter. Another big jolt could crack them there cement ponds.

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  7. Hopefully, TEPCO are already working on alternative plans, if they don't have these now, in case there are points on which NISA does not allow them to proceed.

    Such creative-solution groups are a place they could really benefit from help from the industry around the world.

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  8. @Will: A list of 'Required reading' books would be great. In the meantime are there introductory sites, or online documents, you consider reliable and well written? (Sorry to be a PITA but I'm not game to look at wikipedia again :-)

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  9. Michio Ishikawa, former head of the Japan Nuclear Technology Institute, has expressed the view that TEPCOs current approach is too peripheral, that the critical need is to deal with the reactors. Everything else, in his view, is a diversion.
    He criticized the current command structure, noting it was not clear. Without giving any specific suggestions, he did say that 'this is a war and we need to build a bridgehead at the reactor itself'.
    Overall, his comments suggest a growing sense of urgency, that the status quo is too dangerous to be tolerated and must be addressed, even at much greater human cost.
    Clearly his perspective and NISAs are somewhat different. Perhaps NISAs note is a response, Japanese style, to Mr Ishikawa's proposal, which was presented in a TV broadcast interview.

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  10. @netudiant: And what Mr. Ishikawa is quoted as saying there is in a number of senses correct. My philosophy is that reactor safety is paramount (and this goes on even after some of the reactor is known damaged) so that the other things should take a back seat. TEPCO appears to be trying to manage the whole site at once. In a perfect world the cognizant safety agency (either NISA or NSC in Japan) and the reactor vendor would be calling the shots on actions pertaining to the reactor itself, leaving the utility to worry about site-wide problems.

    NISA is beginning to become a little more aggressive, even if that aggressiveness might cost TEPCO its bid to fill the dry wells of the reactor plants.

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  11. If the vessel and/or piping is/are leaking then YES DO IT, what are they going to do. In order to eventually defuel the vessel it will have to be flooded eventually. Engineers thinking like lawyers and ignoring the obvious reality.

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