ML20079N359
| ML20079N359 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 01/25/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-84-269-000 83-15, 83-19, PT21-84-269, PT21-84-269-000, NUDOCS 8401300193 | |
| Download: ML20079N359 (2) | |
Text
- l '
,, TENNESSEE, VALLEY AUTHORITY
~
./
CHATTANOOGA, TENNESSEE 374ot 400 Chestnut Street Tower II
,...U N0 : 0 B Januai.y 25, 1984 a
BLRD-50-438/83-19i BLRD-50-439/83-15 U.S. Nuclear Regulatory Commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - PRESSURE DROP ACROSS VELAN 2-1/2-INCH STOP/ CHECK VALVE - BLRD-50-438/83-19, BLRD-50-439/83 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector A. K. _ Hardin on February 2,1983 in accordance with 10 CFR 50.55(e) as NCR 2212. This was followed by our interim reports dated March 3 and September 20,- 1983 Enclosed is our final report. We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills,' Manager Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosurc)
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 8401300193 840125 WCIAL COP 1' PDR ADOCK 05000438 r,
L PM dt 2./
d An Equal Opportunity Employer
\\
ENCI,0SURE g *1 BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2
'~
PRESSURE DROP ACROSS VELAN 2-1/2-INCH STOP/ CHECK VALVE NCR 2212 BLRD-50-438/83-19, BLRD-50-439/83-15 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency During flushing operations of the makeup and purification (MU/P) and high pressure injection (HPI) systems, seven of nine 2-1/2-inch 1500 lb. Velan stop/ check valves intermittently failed to D211y open and/or have shown indication of excessive pressure drop.
Velan has determined by testing that the cause of the excessive pressure drop and the intermittent failure of the valves to fbily open can be attributed to the insufficient area of holes in the valve disc which connects the dcwnstream side of the valve with the area above the disc. The root cause of this deficiency can be attributed to a design error committed on the disc drawing which was intended to reduce machining time. The full effect of this reduced equalizing area was not realized until the testing was performed following the incident at BLN.
Safety Implications Failures of these valves could cause HPI, which is required for postaccident cooling, to be lost to the reactor coolant system (RCS),
or the RCS pressure boundary could be violated during normal operation if there is a pipe break upstream of the subject valves. Thus, the safe operation and shutdown (postaccident) of the plant could be adversely affected.
Corrective Action Velan has reviewed all stop/ check and piston check discs and has determined that the discs must be modified by drilling four holes in the sides of the discs. The existing valve discs for unit 1 are to be replaced with Velan-supplied newly modified valve discs by March 26, 1984. All unit 2 stop/ check valve discs will be modified by June 28, 1985.
To prevent recurrence of this deficiency, Velan is revising disc drawings to incorporate design changes, where necessary, to assure that proper clearances and adequate pressure equalization passages are provided for proper operation.
.