ML19341D730
| ML19341D730 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/03/1981 |
| From: | Bishop C NRC ATOMIC SAFETY & LICENSING APPEAL PANEL (ASLAP) |
| To: | VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| ISSUANCES-OL, NUDOCS 8104080547 | |
| Download: ML19341D730 (4) | |
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Administrative Judges:
g Alan S. Rosenthal, Chairman 1
3f Dr. John B. Buck APR O 7
%g 8Pg Dr. Lawrence R. Quarles dy QO In the Matter of
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VIRGINIA ELECTRIC AND POWER COMPANY
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Docket Nos. 50-338 OL
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50-339 OL (North Anna Nuclear Power Station,
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Units 1 and 2)
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MEMORANDUM AND ORDER April 3,
1981 l
In our unpublished February 23, 1981 order (at p. 3), we gave "our approval to the resumption of Unit 1 operation at such time r
I as the NRC staff is satisfied that the replacement [turbinel rotor has been properly installed".
The order went on to note that the question of the timing of the next turbine inspection of that unit l
re=sined open.
In this connection, the staff was then reconsider-1 ing its analytical model pertaining to disk crack growth in light l
of the recent cracking experience at the Farley facility.
We in-dicated that, ones the results of that reconsideration (as applied to this unit) were.in hand, we would " determine the appropriate next. step on the reinspection cuestion".
Id. at p.
4.
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68 I
8104080547
- By letter of March 9, 1981, the staff has recommended that the Unit 1 turbine disks be reinspected at the next refueling outage.
Attached to the letter is the analysis which prompted the recommendation -- an analysis involving some modifications in the assumptions which had been previously made by the staff for the purposes of its crack growth model.
In the absence of any challenge to it on the merits,U /
our scrutiny of the staff recommendation has been conducted under the review standard most recently applied in a related context 1/
In a March 20, 1981 letter from its counsel, the applicant indicated that it did not " object to ultrasonically in-specting the North Anna 1 low-pressure rotors during the l'
next refueling outage, which is currently scheduled te be-gin in mid *982".
It nonetheless suggested that, "to allow some flexibility", our order provide that the rein-l l
spection take place "after no more than a specified nurber
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of hours of operation since the last inspection".
In this connection, we are reminded that "[r]efueling schedules
[
can change according to a variety of circumstances, and it l
is conceivable that it might becore advantageous to inspect either before or af ter the next refueling outage but still l
l within the specified number of operating hours".
l Manifestly, our adoption of the staff's recommendation would not preclude a reinspection of the Unit 1 turbine disks prior to the next refueling outage (should the appli-cant be required.to shut the facility down for other rea-sons).
We thus infer that the applicant's essential con-cern is that an untoward development might bring about a l
refueling outage at a considerably earlier date than now conte = plated.
l offhand, there would appear to be only one such possible development -- the need to replace the recently loaded fuel in the unlikely event that it is found to be defee-tive.
Be that as it may, the staff's reinspection recom-l mendation obviously assumes a normal interval between re-l fuelings. Should that assumption prove contrary to f act, the applicant would be frec to seek a change in the timing l
of the reinspection.
In our view, the availability of that relief provides sufiicient flexibility.
i
- i l
in Northern States Power Co. (Monticallo Nuclear Generating Plant, Unit 1), ALAB-620, 12 NRC 574 (1980).
More specifically, we have confined the inquiry to whether the staff's approach to the rein-spection question is plausible and the conclusion reached on that j
I question is accompanied by an explanation sufficient on its face.
i 12 NRC at 576-77.
We find in the affirmative on both scores.
Thus, the reinspection question will not be explored further at this time.
l Prior to the next Unit I refueling outage, 2/ Unit 2 undoubt-edly will ne shutdo.in for the same purposes.
We would assume that l
at that time the Unit 2 turbines will undergo an ultrasonic in-j spection to ascertain the existence of disk cracking.
It is, how-ever, unnecessary for us now to issue explicit directions in that regard.
For, as also pointed out in our February 23 order (at
- p. 4), in the interim it may prove possible to conclude the ad-Judication of the turbine missile issue in this proceeding "on the strength of a demonstration that the protective turbine covering would contain turbine missiles generated by a crack-induced [ disk)
_2 /
Precisely when that outage will occur is, of course, not now determinable as a matter of certainty.
It will depend upon the future operating history of the unit.
- Because, a
however, the turbine disk cracking problem is similarly tied to length of operation, this consideration is unim-portant here.
Stated otherwise, we have endorsed the staff's conclusion that the reinspection of the turbine disks can await the completion of that number of hours of actual re-acter operation as would necessitate routine refueling --
whenever that point happens to be reached.
t i
-4 f ailure 3/ (with the consequence that the risk of such a missile striking a safety structure or component is acceptably low)".
Should that contingency materialize, it will no longer be neces-sary for this Board to concern itself 'with either the frequency or the product of North Anna turbine inspections.
The turbine manufacturer is studying further the subject of the capabilities of the protective covering.
During the course of our February 19 site visit, we were led to understand that the results would likely be available in late April.
Once received.
the staff will, of course, require an opportunity to evaluate those results before formulating its own position on the question.
We will expect that evaluation to be conducted with all possible expedition to the -end that our own consideration of the matter is not unduly delayed.
l It is so ORDERED.
FOR THE APPEAL BOARD O,Ne4A-4 C. J Qn Bisnop
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Secrecary to the I
Appeal Board 1
--3/
The February 23 order inadvertently referred to " blade" instead of " disk" failure.
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