ML20072V350
| ML20072V350 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/06/1983 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8304110563 | |
| Download: ML20072V350 (5) | |
Text
_
4 O
TENNESSEE VALLEY AUTHORITY o
CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II April 6, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Mr. Denton:
In the Matter of the
)
Docket Nos. 50-259 Tennesses Valley Authority
)
50-260 50-296 In a letter from D. G. Eisenhut to H. G. Parris dated January 19, 1983, TVA cooperation was requested in the Seismic Safety Margins Research Program. We have studied the program as described in that letter and have decided to decline participation. Additional discussion of our decision and conclusions is enclosed.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Licensing Subscribe,,d d sworn to beforg me this (9 day of 1983 f
(
l Notary Public
~
My Commission Expires
/
I
)IcA Enclosure g
cc: See page 2 8304110563 830406 PDR ADOCK 05000259 P
PDR An Equal Opportunity Employer
. Mr. Harold R. Denton April 6, 1983 cc (Enclosure):
U.S. Nuclear Regulatory Commission Region II ATTN: James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Mr. R. J. Clark Browns Ferry Project Manager U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 E
l I
4 e
9 Y.
1
~
m___..
7
-r-
ENCLOSURE RESPONSE TO D. G. EISENHUT'S LETTER TO H. G. PARRIS DATED JANUARY 19, 1983 SEISMIC SAFETY' MARGINS RESEARCH PROGRAM BROWNS FERRY NUCLEAR PLANT TVA declines participation in the SSMRP for the following reasons.
1.
TVA's Division of Engineering Design and Pickard, Lowe and Garrick, Incorporated, are presently performing a very similar analysis as part of the Browns Ferry full-scale Probabilistic Risk Assessment (PRA). We do not foresee any new information from the SSMRP.
Neither do we see any manner in which this program will benefit TVA.
2.
In the letter permission was requested to send a team of analysts to the plant for approximately two days for purposes of observing structures and equipment, examining plant documentation, and discussing plant operation and maintenance with personnel.
Accommodating such a visit requires additional personnel for escort duties. It would also have'some adverse impact on workload of key plant personnel and management while such a team is onsite.
Fucthermore, we do not believe such a site visit will provide any meaningful information concerning seismic qualification of equipment and structures, nor a better understanding of seismic events.
3 TVA personnel of the Division of Nuclear Power are unavailable for any support of this program. The majority of the Browns Ferry IREP personnel have left Idaho National Engineering Laboratory (INEL).
Therefore, much of the knowledge is no longer available at INEL. As a result, we anticipate receiving r.umerous requests for additional information from NRC and/or Lawrence Livermore National Laboratories. Use of the INEL data is denied.
4.
We believe that any additional activities in the area of Probabilistic Risk Assessment (PRA) will have adverse impact on our ongoing PRA activities by detracting responsible experienced TVA pGrso2ael.
l l
l l.
f
- 5.
The amount of information needed to perform the, study, as outlined in enclosure 2 of the January 19, 1983 letter is tremendous. While some of the information is readily available, it represents a very small portion (less than 10 percent) of that requested. The remainder of the;information would be extremely labor intensive to obtain, if at~all possible. A rough estimate of the manpower required would be approximately 12-24 man-months plus a dedicated drawing reproducing machine for three to four weeks. Note that even if the INEL data base requested was provided by INEL, this would only redu.ce the work load by about 20 percent.
1 Specific comments on some of the tasks outlined in enclosure 1 of the January 19 letter are as follows.
Task 1 A complete system model including fault trees and event trees (i.e., a full-scale probabilistic risk assessment) is required. It is proposed that the PRA performed by INEL for the IREP include seismically-induced passive failures. At this point in our preliminary assessment of the
'IREP PRA on Browns Ferry, we find that major technical inaccuracies exist and that-further use of the report would merely propagate existing errors.
Task 2 This task is proposed to detenmine whether any salient differences in structural response characteristics exist between BWRs and PWRs to ascertain whether PWR uncertainties are applicable to BWRs. Due to the
" inverted light bulb" shape of a BWR Mark I containment, differences are j
likely and will probably result in a separate set of structural uncertainties. In addition, BWR Mark II or Mark III containments are j
different yet and would require still further study.
. Task 3 This task is proposed to analyze hydrodynamic loads caused by SRV opening and closure, vent clearing, suppression pool swell, chugging and condensation acceleration, etc. TVA has been and still is in the process of a multimillion dollar program to upgrade the Browns Ferry Mark I containment to address these exact loads. It would be counterproductive l
to reopen regulatory issues in this general area.
P rie
..-m,
,.m.
-,,_.~..,,e,...,
-,,,_.,..y.._,
. Task 6 This task is proposed to develop a local site hazard curve and time history for seismic events. This 'information has already been developed and is presented in the Browns Ferry FSAR, table 2.5-1, and figure's 2.5-6,
-8, and -9 Conclusions Browns Ferry has been designed for an Operating Basis Earthquake of 0.1g ground acceleration. In addition, Browns Ferry is conservatively designed to be able to be shut down with a Design Basis Earthquake of 0.2g.
Thus, given the probability of an earthquake of large intensity plus the additional design conservatisms, Browns Ferry's safety systems are very conservatively designed for operating during the remaining plant lifetime.
t e
Aw.
sm s.
.x
.s