ML18114A626
| ML18114A626 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 05/03/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-79-04, IEB-79-4, NUDOCS 7905300706 | |
| Download: ML18114A626 (4) | |
Text
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VIRGINIA ELECTRIC.AND POWER COMP.ANY RICHMOND, VIRGINIA 23261 c..o 3:
Mr. James P. O'Reilly,*Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta Street~ Suite 3100 Atlanta, Geo_:rgia 30303 May 3,. 1979
Subject:
- I.E~ ~ulletin 79~04
Dear Mr. O'Reilly:
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co Serial No.
2flA/033Q79 PO/D:!:,B :baw 5'0=280 50..;za1 50-338" License Nos.:
DPR-32 DPR-37 NPF-4 This is in response to IE Bulletin 79....:04, "Incorrect Weights*for Swing Check Valves Manufactured by*Velari ~ngineet~ng Company".
The information requested for Surry Power Station Unit Nos.*1 and 2 is included in Attachment
- 1.
The information requested.for North Anna Power Station Unit No. 1 is included in Attachment 2, Attachments (2)
- I i
I cc:
NRG Office of Inspection and Enforcement Division of Reactor Operations and Inspection Washington, D. c.* 20555
~905300766
flt Docket Nos:
50-280 50-281 RESPONSE TO IE BULLETIN 79-04 SURRY POWER STATION UNIT NOS. 1 AND 2 The following is the information requested in the subject. bulletin.
Number sequence is the same as in the bulletin.
- 1.
Velan swing check valves, sizes 3 inch and 6 inch, are installed in the following Seismic Category I piping systems:
a) chemical volume and control system b) safety injection system All 3 11 valve applications are in the chemical and volume control system.
All 6,, valve applications are in the safety injection system.
- 2.
The valve weights listed on the manufacturers' drawings are incorrect.
It is assumed that these incorrect weights were used in computer analysis.
- 3.
Lines with 6 inch check valves were seismically analyzed by computer program.
The re-evaluation of these systems using the correct valve weight is currently in progress, using the NUPIPE program.
Lines with 3 inch check valves were analyzed by hand calculations. A conservatively estimated weight was used in those calculations instead of actual valve weights.
Thus, the incorrect valve weight had no effect on the hand calculations and re-evaluation is not required.
- 4.
The re-evaluation of the safety injection system, in which the 6 inch valves are located, is currently in progress.
Modifications, if required, will be determined at a later date.
- 5.
As indicated in item 3, the NUPIPE computer code is being used to determine.
the pipe stresses.
Docket No. 50-338, page 1 RESPONSE TO IE BULLETIN 79-04 NORTH ANNA POWER STATION UNIT NO. 1 The following is the information requested in the subject bulletin.
Number sequence is the same as in the bulletin.
- 1.
Velan swing check valves, sizes 3 inch and 6 inch are installed in the following Seismic Category 1 piping systems.
a) chemical and volume control system b) safety injection system There are twelve 3 inch and fourteen 6 inch velan check valves installed in Unit No. 1.
- 2.
The check valve weights used in the applicable pipe stress analysis were those provided on the manufacturers drawings and :were in error.
For 3 inch valves 60 lbs. was used and for 6 inch valves 225 lbs was used.
- 3.
As explained in our Licensee Event Report No. 79-035-0lT-0 the use of erroneous weights for the 6 inch valves was identified on March 19, 1979.
All portions of piping systems containing these 6" valves were reanalyzed to determine if the design was adequate for the higher valve weights.
One pipe hanger was identified as overstressed and five other hangers needed adjustments or modifications to return them to origina} design margins.
All required adjustments artd modifications have been completed.
Regarding the 3 inch valves, we have directed our architect engineer to reanalyze all portions of piping systems containing the 3 inch valves.
Certain of these stress problems were originally performed by a consultant to the architect engineer.
As a result of this additional interface, the*
reanalysis has been slower than expected and has not been completed at this time.
However, we do not expect any need for modifications for two reasons:
- 1)
The relative size of the error in valve weight is much smaller for the 3 inch valves than for the 6 inch valves.
The three inch valves were originally assumed to weigh 60 lbs. versus an actual weight of~85 lbs.
The 6 inch valves were assumed to weigh 225 lbs. versus an actual weight of 450 lbs.
- 2)
For North Anna Unit No. 2, the pipe stress problem estimated to have the worst case impact from the error in 3 inch check valve weights has been redone, using the higher valve weights.
The results showed negligible increases in stresses.
Similar results are expected on Unit No. 1.
The analysis should be completed by May 18, 1979.
Results will be for-warded immediately upon completion.
-, page 2
- 4.
Information on modifications required to those lines containing the 6 inch valves was provided in Licensee Event Report 79-035/0lT-0.
Information regarding the need for or nature of any modifications to systems containing the 3 inch valves is not available pending completion of reanalysis.
S.
Reanalysis of the system portions containing the 3 inch valves will be done with the same codes as docketed in the FSAR and described in the Class 1 stress reports.