ML20140F525
| ML20140F525 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 06/11/1985 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8507120111 | |
| Download: ML20140F525 (2) | |
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6k TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II June 11, 1985 co BLRD-50-438/84-28
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BLRD-50-439/84-27 g
U.S. Nuclear Regulatory Commission N
Region II
.3 Attn:
Dr. J. Nelson Grace, Regional Administrator m
101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 c.o w
Dear Dr. Grace:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - TARGET ROCK SOLENOID VALVES ON POSTACCIDENT SAMPLING FACILITY (PASF) DO NOT MEET BACKPRESSURE REQUIREMENTS -
BLRD-50-438/84-28 AND BLRD-50-439/84 FINAL REPORT
'The subject deficiency was initially identified for Watts Bar Nuclear Plant (WBN) and reported to NRC-0IE Inspector P. E. Fredrickson on February 15, 1984 in accordance with 10 CFR 50.55(e) as NCR WBN WBP 8410 (WBRD-50-390/84-10 and WBRD-50-391/84-10. Our first interim report for WBN was submitted on March 15, 1984. On March 27, 1984, C. A. Julian was notified that the subject nonconformance report BLN EEB 8403 for Bellefonte Nuclear Plant (BLN) would be combined with the WBN report. Our final report for UBN and first interim report for BLN was submitted on April 27, 1984. Enclosed is our final report for BLN.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
. W. Hufham, Manager Licensing and Regulations Enclosure cc:
Mr. James Taylor, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8507120111 850611 DR ADOCK 05000438 g
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a ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 TARGET ROCK SOLENOID VALVES ON POSTACCIDENT SAMPLING FACILITY (PASF)
DO NOT MEET BACKPRESSURE REQUIREMENTS BLRD-50-438/84-10 AND BLRD-50-439/84-10 10 CFR 50.55(e)
NCR BLN EEB 8403 FINAL REPORT Description of Deficiency During a generic review for Watts Bar Nuclear Plant (WBN) nonconformance report (NCR) WBN WBP 8410 (WBRD-50-390/84-10, WBRD-50-391/84-10), TVA determined that Target Rock process solenoid valves were also being used at Bellefonte Nuclear Plant (BLN) postaccident sampling facility (PASF) lines as containment isolation valves, and as at WBN, these valves would see a back-pressure during a loss of coolant accident (LOCA) which would keep the valves from gemaining closed. At BLN, the valves could see a backpressure of 25 2
lb/in g resulting in a differential pressure which exceeds the 5 lb/in differential design limit of the valve. This was caused by a failure to recognize that, on "open. ended" piping inside containment, a LOCA would result in a reverse differential pressure across the isolation valve.
Safety Implications Because these valves could not have performed their intended containment isolation function, a breach of containment could have resulted during a LOCA, and this condition could have adversely affected the safe operation of the plant.
Corrective Action Design drawing revisions have been completed and field modifications will be completed by June 30, 1986, through engineering change notice (ECN) 3237 to reorient the affected valves so that the vendor-recommended valve flow direction is opposite the system flow. This allows the inlet port of the In this valve to be connected to the downstreap side of the process line.
configuration, the postulated 25 lb/in d pressure caused by a design-basis earthquake LOCA will appear at the inlet port which is consistent with the valve design and will allow the valve to close and remain closed during containment isolation. This " reversed" configuration is functionally acceptable and will not adversely affect the valves dur ing normal operation.
To prevent a recurrence of this problem, TVA has issued design standard DS-E18.3 5 which includes a data sheet specifically for procuring process solenoid valves. Valve backpressure design considerations is an entry on this data sheet and is required to be addressed by the originating organization.
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