ML18031B058
| ML18031B058 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/25/1986 |
| From: | Gears G Office of Nuclear Reactor Regulation |
| To: | TENNESSEE VALLEY AUTHORITY |
| Shared Package | |
| ML18031B059 | List: |
| References | |
| GL-83-08, GL-83-8, TAC-57144, TAC-57145, TAC-57146, NUDOCS 8612080628 | |
| Download: ML18031B058 (6) | |
Text
I aov 35 igs6 Dockets Nos. 50-259/260/296 Manager of Nuclear Power Tennessee Valley Authority 6N 32A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801
Dear Sir:
SUBJECT:
MODIFICATION OF VACUUM BREAKERS ON MARK I CONTAINMENTS (GENERIC LETTER 83-08);
MPA D-20 Re:
Browns Ferry Nuclear Plant, Units 1, 2, and 3
In December of 1979, the General Electric Company (GE) issued Service Information Letter (SIL) No. 321 informing customers of unanticipated cycling and damage to drywell vacuum breakers during LOCA tests in a Mark I containment full-scale test facility.
The SIL addressed the possibility of vacuum breaker failure due to chugging.
Failure due to pool swell was determined to be not applicable to Mark I Containments (Ref:
Safety Evaluation, Letter from Vassallo to Pfefferlen, dated May 5, 1983).
To assure that drywell vacuum breakers would be capable of withstanding chugging loads, the staff issued Generic Letter 83-08 on February 2, 1983, requesting licensees of Mark I BMRs to submit results of calculations which provide bases for either (1) modifications to the vacuum breakers, or (2)
Justification that the as-built vacuum breakers are acceptable.
In your letter dated November 5, 1984 you provided the requested information, describing the results of your analysis which concluded that no modifications are necessary as the valves had been modified earlier.
Your analysis was based on the Mark I Containment generic load determination methodology described in CDI Tech Note 82-31 of October 1982.
In SIL No. 321, Supplement 1 of August 24, 1984, GE announced the availability of plant specific methodology.
The plant specific methodology is dqscribed in an enclosure (CDI Report No. 81-2) to a letter from H.
C. Pfefferlen to D.
B.
- Vassallo, dated September 26, 1984.
The Staff Evaluation of the plant specific methodology was completed on December 24, 1984 (Letter from Vassallo to Pfefferlen dated December 24, 1984).
The evaluation describes restrictions and conditions on the use of the model.
These conditions and restrictions ensure conservatism in determining the pallet impact velocity loads on the vacuum breakers during chugging.
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On January 17, 1986 we sent you a Request for Additional Information (RAI).
The purpose of this RAI was to obtain verification that the pallet impact velocity used in your vacuum breaker stress analysis was determined using the approved methodology consistent with the conditions and restrictions prescribed by the staff.
Your response dated April 7, 1986, indicated that the stress calculations were based on the use of conservative values of pallet impact velocity.
The staff's technical assistance contractor, Franklin Research Center (FRC),
has reviewed the results of the stress analysis to verify that the vacuum breaker stresses are within the ASME code allowable values for the materials used.
Their Technical Evaluation Report is appended to our Safety Evaluation which is enclosed for your information.
Based on our review, we conclude that the analyses performed to predict the drywell vacuum breaker impact velocities and resulting stresses, were performed using acceptable methodology and that the modified vacuum breakers will not be subjected to excessive stress as a result of LOCA chugging and condensation oscillation loads.
Your letter of November 5, 1984, stated that the proposed vacuum breaker modifications had been completed on Browns Ferry Unit 3.
Modifications schedules for Unit 2 and Unit I were also provided.
Please provide an updated status of these modifications within 45 days of the receipt of this letter.
This completes our review of Multiplant Action Item 0-20 for the Browns Ferry Nuclear Plant, Units 1, 2, and 3. If you have any questions concerning,our review, please contact either of the NRR Project Managers, Gerry Gears or Marshall Grotenhuis at (301) 492-8026.
Sincerely, gAPyal~ ay Gerald E. Gears, Project Manager BWR Project Directorate ¹2 Division of BWR Licensing
Enclosure:
As stated cc w/enclosure:
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Manager of Nuclear Power Tennessee Valley Authority Browns Ferry Nuclear Plant Units 3., 2, and 3
cco General Counsel Tennessee Valley Authority 400 Commerce Avenue E 11B 330 Knoxville, Tennessee 37902 R.
W. Cantr ell Acting Director, Nuclear Engineering Tennessee Valley Authority 400 West Summit Hill Dirve, W12 A12 Knoxville, Tennessee 37902 R. L. Gridley Tennessee Valley Authority 5N 157B Lookout Place Chattanooga, Tennessee 37402-2801 M. J.
May Tennessee Valley Authority Browns Ferry Nuclear Plant Post Office Box 2000
- Decatur, Alabama 35602 H. P.
Po'mrehn Tennessee Valley Authority Browns Ferry Nuclear Plant Post Office Box 2000
- Decatur, Alabama 35602
- Chairman, Limestone County Commission Post Office Box 188
- Athens, Alabama 35611 Ira L. Meyers, M.D.
State Health Officer State Department of Public Health State Office Building Montgomery, Alabama 36130 Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, Suite 2900 Atlanta, Georgia 30303 Mr. Steven Roessler U. S. Nuclear Regulatory Commission Reactor Training Center Osborne Office Center, Suite 200 Chattanooga, Tennessee 37411 Resident Inspector U. S. Nuclear Regulatory Commission Route 2, Box 311
- Athens, Alabama 35611
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