ML18153B490
| ML18153B490 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/29/1988 |
| From: | Cruden D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 88-118, IEB-88-004, IEB-88-4, NUDOCS 8808080064 | |
| Download: ML18153B490 (3) | |
Text
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D.S.CRUDEN VICE PRESIDENT-NUCLEAR VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 July 29, 1988 United States Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D. C.
20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY.
SURRY POWER STATION UNITS I & 2 AUXILIARY FEEDWATER SYSTEM STATUS Serial No.
NO/ETS:vl h Docket Nos.
License Nos.88-118 R8 50-280 50-281 DPR-32.
DPR-37 This letter documents a May 26, 1988, telephone conference call between Mr.
L. Reyes and other members of your staff and Mr. D. Benson and other members of my staff regarding the status of the Unit 2 Auxiliary Feedwater (AFW)
System.
Current system status, modifications, operational* concerns, post modi fi cation and inspection system* testing, and 1 ong term preventive maintenance and testing were discussed.
Following a reactor trip on May 16, 1988, a reduced flow condition was observed in AFW flow to the "A" steam generator.
Subsequent investigations and eval~ations determined that a part from a 38 AFW pump diffuser vane had broken 1 oose and had obstructed fl ow through the cavi tat i ng venturi in the line to "A" steam generator.
As a result, the three AFW pumps were disassembled and an inspection was performed on the pump internals. The pump manufacturer's technical represent-atives and our meta 11 urg i st examined the pump i nterna 1 s and the recovered pieces of di ff user vane.
A dye penetrant examination was performed on the vanes.
Evaluation of the failed and cracked parts indicate a cyclic mechani-cal stress generated by mechanical or thermal stresses.
The missing diffuser parts were evaluated against pump performance and operabi 1 i ty and it was determined that these missing parts did not affect the pump operation.
When the Unit 2 AFW system was opened, the majority (71%) of the nonvertical AFW piping was inspected internally for loose parts and foreign materials.
The remaining runs on nonvertical piping not internally inspected were evaluated for potential loose part traps.
No potential traps were identified.
The internal.pipe inspections located five pieces of foreign material (i.e.,
three pieces of diffuser, two pieces of bronze and one piece of welding slag).
However, portions of the missing diffusers have not been located.
The missing portion(s) totals approximately 5/8 11 x 3/16" x 1 1/2"., We believe that this portion('s) has broken into smaller pieces and may have passed through the venturis.
A loose parts safety analysis has been performed to evaluate the impact on system operation if any such pieces have passed into the steamt\\oO \\
generators.
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Any diffuser vane that exhibited cracking was replaced.
Similar inspections were completed on the three Unit 1 pumps prior to returning to service from the recent refueling outage.
The pump manufacturer (Ingersoll Rand) recommended a three year service life and therefore each pump (Units 1 & 2) will be put on an every second refueling outage inspection and rebuild preventive maintenance schedule.
The inspections wi 11 include dye penetrant examination of pump internals for cracking.
To reduce the possibility of future flow blockage in the AFW system, strainers were installed in the Unit 1 and 2 AFW pump discharge lines.
Post fabrication radiographs were taken of a strainer to verify that a loose part similar to the pieces found could be identified and to establish baseline data for future inspections.
Prior to startup, flow testing was completed on both units.
Flow testing consisted of full flow tests with each motor driven pump prior to leaving cold shutdown and a flow test of the steam driven pump when the unit was critical but less than 10% as required by Technical Specifications.
A response to NRC IE Bulletin 88-04 is being prepared.
This response will address operation of safety-related pumps, including the AFW pumps, in the recirculatic;>n mode.
An AFW pump recirculation line modification is in the early design phase, and is scheduled to be installed during the 1989 and 1990 refueling outages.
Should you have any questions, please call.
Very truly yours,
~-------
cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. Charles Price Department of Health 109 Governor Street
- Richmond, Virginia 23219 Mr. Chandu P. Patel NRC Surry Project Manager Project Directorate II-2 Division of Reactor Projects - I/II