ML20117C620
| ML20117C620 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Browns Ferry |
| Issue date: | 11/08/1983 |
| From: | Olshinski J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Robert Lewis NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20114F930 | List:
|
| References | |
| FOIA-84-616 831108, NUDOCS 8505090474 | |
| Download: ML20117C620 (3) | |
Text
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September 26, 1983 TO:
Floyd Cantrell, Section Chief FROM:
G. L. Paulk, Senior Resident, Browns Ferry
SUBJECT:
MAIN STEAM RELIEF VALVE TAILPIPE
,10" VACUUM BREAKERS 1.
The resident office at Browns Ferry requests regional technical support to evaluate design adequacy of the newly modified GPE 10" main steam relief valva (MSRV) tailpipe vacuum breakers. Due to past failures of the original GPE desi&ned vacuum breakers, the licensee instituted a modification program to change the operating mechanism and strengthen the vacuum breaker ass.embly parts. This modification effore took place in February, 1983. The modified valve was then tested for operability at Wyle Labs, Huntsville, Alabama on February 28, 1983. Test results indicated the pallet would bounce off the seat when the pallet closed and would remain off its seat until manually pushed back to the seat.
Also, during che test phase the originally required hydrostatic and seat leak tests were deleted as not being necessary.
Due to the pallet failure to ressat, the licensee took the vacuum breaker back to the site and redesigned (skill of craft type design) the valve to increase the spring preload and to prevent the pallet hinge arm from rotating out of position.
After the redesign the vacuum breakers were installed on Unit 2 without any additional testing.
Specific details are included in I.E. Report 83-23 s
paragraph 9.
The valve was retested on August 30-31, 1983, with the resident inspector present to observe the testing.
The remedified valve 8505090474 841002 PDR FOIA BARFIELB4-616 PDR l
'w.
1, y
Floyd Cantrell 2
9/26/83 o
(as currently installed on the operational Unit 2) again failed to have its pallet reseat after operation.
The licensee reworked the test valve anddeterminedtheTVAmanufacchedbushingswerenotmadetoexacting N
dimensional requirements and would have to be reworked.
After reworking and on the third series of. qualification tests the valve passed its tests on September 23, 1983.
Specifically, the resident office requests the following regional 2.
positions:
What safety concern is involved with failure of a steam relief a.
tailpipe vacuum (or all 13 vacuum relief valves) breaker pallet to resent after cycling?
(vacuum breakers, if left open, discharge directly to the, rywell) d Should all qualification tests on nuclear components be satis-b.
factorily completed prior to their operational use even though a licensee generated safety evaluation may deem this not necessary?
(Th's inspector is concerned about the validity of the TVA safety evaluations in this specific. case.)
Can original design criteria such as hydrostatic and seat leak c.
tests be deleted as too stringent and not necessary for steam relief tailpipe vacuum breaker valves? All original and TVA modified tests are attached for your review.
d.
Is there a safety concern with allowing Unit 2 to continue to operate with the increased probability of valve failure due to known manufactured bushing tolerance inadequacies?
,b, G. L. Paulk 5
.