ML20039B769
| ML20039B769 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 12/14/1981 |
| From: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| To: | Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| REF-PT21-81 10CFR-050.55E, PLA-977, NUDOCS 8112230539 | |
| Download: ML20039B769 (4) | |
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@ Pennsylvania Power & Light Company Two North Ninth Street
- Allentown, PA 18101
- 215 1 770'5151 Norman W. Curtis Vice President-Engineering & Construction-Nuclear 215 / 770-5381 December 14, 1981 Mr. R. C. Haynes e
e Director, Region I U. S. Nuclear RDgulatory Commission h
631' Park Avenue Rgg King of Prussia, Pennsylvania 19406 S-ITD DEC2 bOIA k' i~-
SUSQUEHANNA STEAM ELECTRIC STATION
~O INTERIM REPORT OF A DEFICIENCY INVOLVING-iWC 8
RHR SYSTEM THROTILING VALVES h
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ERs 100450/100508 FILE 821-10 64 PLA-977 kTTD
Dear Mr. Haynes:
This letter serves to provide the Commission with an interim report of a performance deficiency in the Residual Heat Removal System (RHR). A problem was identified with several Anchor / Darling globe valves.
It was found.that the valves either cavitated or were difficult to throttle within the Technical-Specification ranges. The deficiency was originally reported by telephone to Mr. E.C. McCabe of NRC Region I by Mr. A. R.
Sabol of PP&L on November 12, 1981 and was considered to be potentially reportable.
The attachment to this letter contains a description of the problem and an analysis of safety implications. Also included is PP&L's approach'to corrective action of this deficiency.
PP&L will provide the Commission with a final report by February 1982.
Since the details of this report provide information relevant to the reporting requirements of 10CFR21, this correspondence is considered to also discharge any formal responsibility PP&L may have in compliance thereto.
Very truly yours, h
,7 UNV N. W. Curtis Vice President-Engineering & Construction-Nuclear JBW:jmk Attachment 8112230539 811254 I5 PDR ADOCK 05000387 PDR S
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. SSES PLA-977 December 14, 1981 ERs 100450/100508 File No. 821-10 cc:
Mr. Victor Stello (15)
Director-Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. G. Mcdonald, Director Office of Management Information & Program Control U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. Gary Rhoads U. S. Nuclear Regulatory Commission P.O. Box 52 Shickshinny, PA 18655
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December 14, 1981 1-SSES PLA-977 ERs 100450/100508 File No. 821-10 Attachment to PLA-977 INTERIM REPORT ON DESIGN DEFICIENCIES ON RESIDUAL HEAT REMOVAL SYSTEM THROTTLING VALVES SUBJECT Anchor / Darling Valve Co. globe valves, used in throttling service.
DESCRIPTION OF DEFICIENCY During start-up testing of the Residual Heat Removal System 1RHR), a problem was identified with the throttling characteristics of several Anchor / Darling globe valves.
It was found that the valves either cavitated or were very difficult to throttle within the Tech'nical Specification ranges.
Specifically, valves F024A and B were required to be throttled closed approximately 85%
to obtain the flow rate required to test the singlc pump Low Pressure Coolant Injection Mode (LPCI) and the single pump Suppression Pool Cooling Mode of the RHR system. This resulted in cavitation as identified by a very loud valve noise.
In addition, valves F017 A and B were uncontrollable in the throttling ranges required for the Shutdown Cooling Mode of the RHR system.
When throttling was attempted by briefly jogging the motor. operator, valve overtravel was experienced and accurate control was not possible.
ANALYSIS OF SAFETY IMPLICATIONS Valves F024A and B are located in the RHR System test lines, and are used both for testing and for cooling water return to the Suppression Pool during suppression pool cooling.
In the suppression pool coolfng mode, valve F024 A or B is required to be throttled to approximately 85% closed with a potential for cavitation damage and, ultimately, valve failure.
, Valves F017A and B are located in' the LPCI injection lines attached to the reactor recirculation lines. They are used for LPCI injection and for shutdown cooling. During the shutdown cooling mode, th'e valve in use must be throttled to control the rate of cooling.
Such throttling cannot be achieved with the present valve. Additionally, attempts at throttling may result in cavitation with subsequent valve damage.
Shutdown cooling is not a design basis accident mode; however, cavitation damage resulting from throttling in'this mode may impair the valve's performance during the LPCI injection mode.
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December 14, 1981 2-SSES PLA-977 ERs 100450/100508 File No. 821-10 CORRECTIVE ACTION Anchor / Darling Vlave Company is presently investigating the possibility of replacing the valve discs in F017A and B with modified discs designed specifically for the required throttling conditions. Other tentative solutions being investigated include total valve replacement (not just the disc), and valve reorientation (turning the valve around in the line to take advantage of the higher pressure drop resulting from flow "over the dise" rather than "under the Disc").
Corrective action will be finalized by February 1982 after an evaluation of the cause has,been completed. Design Change Packages (DCP) 556 and 558 are being issued to document the corrective action.
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