ML19210C584
| ML19210C584 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 10/31/1979 |
| From: | Chilk S NRC OFFICE OF THE SECRETARY (SECY) |
| To: | Allen J NORTH ANNA ENVIRONMENTAL COALITION |
| Shared Package | |
| ML19210C589 | List: |
| References | |
| NUDOCS 7911190144 | |
| Download: ML19210C584 (5) | |
Text
.
D
, f' * %
UNITEC STATES
[I f.U': LEA: REGULATORY COMMISSloN
%e E$
- v. ass Noro.. o. c. 2csss DOCKET NUi.fSER PROD.& UriL FAc..h@ '5 37 04 iI,N'> /
October 31, 1979
,. 4 m
....'4 a
.9 oc3$l q
~
1 gg7BY L Ms. June Allen, President
$01 Y *d ** d North Anna Environmental Coalition 212 Owens Drive N
HJntsville, Alabara 35301 p
Dear Ms. Allen:
m
/
In your letter da ec August 13,1979, you presented a chronology related to resolution cf the metal-water reaction error in the Westinghouse ECCS model.
Based on that chronclogy you note that the problem was resolved for North Anna rapidly (in 4 days), but still appears to be unresolved for Westinghouse plants generically after a year and.a half. With this information you question whether tne quick solution for North Anna could possibly be valid.
A somewhat expanded chrcnolcgy should help to clear up these problems:
March 23,1978 -
Westinghouse informed the staff that they had discovered an errcr ir. the LOCTA computer program used at Horth Anr.a and other Westinghouse plants to calculate peak cladding temperature (FCT) ir. their ECCS evaluation model.
March 29,1978 -
Westingtouse made a detailed presentation on the subject in 3Ethesda to the staff and the utilities with operating Westingtouse plants. The error resulted in.a calculation of the metal-water reaction heat release at one-half of what it should te.
(The error also existed in SATAN, a computer program which is part of the same ECCS analysis.) The error and its tathematical confirmation were explained.
Westinghouse cerformed calculations with the error corrected which 6
sFowed. hat some plants would not meet the 2200 F lir.it of IC CFR E3.46.
Correction of the error always results in an ir. crease in PCT because of higher heat release calculations.
The magr.itude of the increase depends on the cladding gupture dyngmics. Generally the increase is in the range of 75 F to 2C'O F.
Ir crder to avoid reductions in overall peaking facter (F and possible reductions in power level, Westinghouse recorh) e o-her can; ensatory changes in their evaluation model.
It was very apparent to the staff that confirmation and correc-tf on of the error were quite straight-forward.
If tre error
'Mha}D " Jow y g 1354 202 O
w ju,1 kfjL u
7911190 1 9 4-
3 May 5, 1978 -
VE?C: submitted another analysis for North Anna (ref. 2).
The rew analysis differed from the March 30 submittal oni-in a*. lowing a slightly higher overall peaking factor. Th's still met JiRC requirements by taking crgdit for the margir between the calculated PCT and the 2200 F require:nent of *.0 CFR 50.46.
May 19, 1978 -
The staff in Amendment 5 to the facility operating licensa appr:ved the new analysis submitted in reference 2 for Nc-th Anna.
June 20,1978 -
The ~.ffice of Nuclear Reactor Regulation (NRR) recommende:
notifying the appropriate hearing boards regarding the West'nghouse ECCS error. The recommendation specifically excl.ded North Anna since a solution was already reached for that plant. (ref. 3)
August 29, 1978 -
The 'iRC infonned Westinghouse (ref. 4) that it had comple:e:
its review of all the ECCS model changes. The SER which acco panied reference 4 defined the acceptability of the vari:us sub-nodels. The staff did not grant all the com-pensating changes requested by Westinghouse.
However, no suos:antive change was made in the original error correct'or described on March 29, 1978.
Since that time, each licensee (excip: 'iorth Anna) has performed analyses using the new mc d e'..
'io mandatory schedule for submitting re-analyses =as irposed since the operating plants were under the safety orders issued April 7-10, 1978.
March 30,1979 -
The 'iRC staff notified the applicable hearing boards as wi1~ as the 'iortn Anna appeal board of the error.
April 13,1979 -
Tre 'iRC staff notified the North Anna appeal board by let e-that the s?e:ific resolution to the error for the North Anna analysis was contained in Section 6.3.8 of Supplemen:
9 to the facility SER (see March 31,1978). Therefore the bcard need not consider any additional solutions since it had :een previously resolved.
May 3, 1979 -
The 'iRC told the North Anna Environmental Coalition that the :roblem had not been resolved finally for all Westin5 ctse pl an s.
The reason for tne delay on other plants was not because of any difficulty in correcting the error.
T at solution was obvious at the presentation on March 29, 1978.
If otner a;:plicants and licensees had opted for the North Anna ty;i solution, a si niiar rapi: resolution could have occurred.
The delay for othe-plants was due to the re.itw recuired for additional compensating mocificaric s.
~
and be:ause of celays ir receiving recalculations from the licensees.
D""D D
1354 203 os c
A o
2 correction was the only issue, a long review would not be required. However, the staff informed Westinghouse that a thorough review of the compensating changes would require several months. Compensatory changes considered include changes in the LOCTA and SATAN computer codes which would offset the increase in PCT calculation.
NRC regulations allow the staff to consider any justifiable change to an ECCS evaluation model presented by the vendor or licensee. The NRC has reviewed changes for each reactor vendor ECCS model in the past. The staff also stated that until a new model was approved and corrected calculations were submitted, interim peaking factors would be imposed on each plant.
Marc 1 30,197E -
VEPCO submittted a reanalysis with the error corrected and notified the North Anna Appeal Board.
VEPC0 did not wish to wait for the possible benefits of the compensating changes for North Anna. Therefore, they submitted a calculation with only the error correction and no claim of compensating benefits.
In fact, North Anna was the only plant which chose this option.
Marc, 31,197E -
The HRC approved VEPC0's 3/30/78 reanalysis in section 6.3.8 of Supplement No. 9 to the North Anna SER (reference 1). The rapid resolution by the staff was because no co,mpensating changes were requested by VEPC0 for the North Anna analysis.
Apri; 1,1978 -
The NRC issued an amendment to the North Anna license for full power operation.
Apri: ?-10, 1978 - NRC issued orders specifying interim peaking factors for all operating Westinghouse FWR's except for North Anna.
The operating utilities were informed that the interim operating restrictions would be in effect until corrected calculations were received and approved by the NRC. The interim peaking factors were based on a substantial penalty for the uncorrected error, an accounting for any existing margin, and a small credit for one of the compensating changes.
1351 204 e
4 You also asked if the 1978 " solution" is rendered invalid by new cladding knowledge from TMI. The answer is no. The kinetics of the metal-water reaction have been studied and known for a long time. The requirements for ECCS analysis in 10 CFR 50 Appendix K described a very conservative procedure of calculating tne extent of metal-water reaction. The problem with TMI was not with the understanding of metal-water reaction kinetics and conditions, but that subi.antial portions of the reactor core were uncovered for extended periods of time.
Given this uncovered core condition, behavior of the fuel and cladding was as would be predicted from present information.
You also requested the Commission to review the August 6 ASLB decision in the North Anna spent fuel pool expansion proceeding granting VEPCO's motion for surrmary disposition. Subsequently the NRC staff issued an amendment to permit an increase in the fuel storage capacity at North Anna 1 and 2. Intervenors have filed a statement of exceptions to the decision and the Licensing Board decision is currently under review by the Appeal Board. After the Appeal Beard rules on the Licensing' Board decision, the Cor: mission will have the o;;portunity to review that decision. A copy of your letter and this response will be placed in the NRC public document room and served by the Secretary on the parties to the adjudicatory proceeding.
All of the references mentioned in this reply are available in the PDR except Ref. 3, which is enclosed.
I hope that this information is responsive to your ccncerns.
[incere{yj
/
$ I'
~
A i
f, J. M ik y Secretary Erclosures:
As stated 1354 205
,,k,ky Y.
L oc c
References
- 1. !!ord Anne. EER, Inpplement No.
9, March 31, 1978.
- 2. C.M.
Sta.11ings (T2?CO), Letter to E.G. Case (NRC), dated May 5, 1973.
- 3. C.E. Vas sallo, A for LWR's, DPM, Letter to M. J. Grossman Eea-ing Division Director, ELD, dated June 20, 1978.
- 4. Cohn F.
Stolz, Chief, LWR Branch 1 (NRC), Letter to T.M.
A.nderson (~4estinghouse), dated August 29, 1978.
1354 206 e
e O