ML20215N623
| ML20215N623 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/22/1986 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20215N624 | List: |
| References | |
| DCC-86-167, FYR-86-106, NUDOCS 8611070087 | |
| Download: ML20215N623 (5) | |
Text
'
Telechone (617) 872-8100 TWX 710 380 7619 YANKEE ATOMIC ELECTRIC COMPANY t
1671 Worcester Road, Framingham, Massachusetts 01701 DCC 86-167 m
ANKEE
,w October 22, 1986 FYR 86-106 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Office of Nuclear Reactor Regulation
Reference:
(a) License No. DPR-3 (Docket No. 50-29)
Subject:
Request for Changes to Technical Specification 4.5.2.b.4
Dear Sir:
Pursuant to Section 50.59 of the Commission's Rules and Regulations, the Yankee Atomic Electric Company (YAEC) hereby requests the authorization to make the following change.
Proposed Change Reference is made to the Technical Specifications of License No. DPR-3.
We propose to modify Technical Specification 4.5.2.b.4 to increase the allowable open time for the LPSI minimum recirculation line valve, CS-MOV-532, from 1 0 minutes per week to 1120 minutes per week.
3 Reason for ChanRe An increase in time to successfully perform proper surveillance testing of the low pressure safety injection pumps is required for the following reasons:
1.
Leakage rates during pump runs must be documented.
2.
Vibration monitoring must be performed during pump runs at normal bearing metal and lubricating oil temperatures.
3.
Pump operating data n:ust be recorded at normal, stabilized operating parameters.
4.
Obtaining constant bearing metal and component temperature and expansion requirements requires a certain amount of operating time before proper inservice testing may be recorded, Y
d {/ l t
00 (0p{
8611070087 861022 N
PDR ADOCK 05000029 P
United StatOs Nuclcar RIgulatcry Commissicn October 22, 1986 Page 2 Dcc 86-167 FYR 86-106 5.'
The capability to immediately correct any discrepancies, however minor, and properly retest the pump and its appurtenances prior to returning the LPSI System to operable status is hindered by the 30-minute time restriction.
Also, if ever the surveillance test has failed and must be reperformed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, it would be necessary to reopen CS-MOV-532 which, under the current requirement, may not be'possible or of sufficient' duration to ensure an' accurate test.
Basis for Change The proposed new time limit of 1120 minutes is based on maintenance testing requirements as reported by plant maintenance personnel. By including an appropriate time allowance for low pressure safety injection pump operating data recording, meaningful and verifiable test data can be recorded without the' inappropriate. time limit placed on maintenance and operating personnel during surveillance testing.
Safety Considerations The proposed 1120 minute open time lir.itation.per week for CS-MOV-532 does not expose the plant to an unreasonably increased chance of LPSI failure on demand due to excessive recirculation flow. Per Attachment A, CS-NOV-532 failure to close on demand is.1% of the total system failure probability.
Increasing the restriction to 120 minutes per week increases total system failure probability to.4% which has an insignificant effect on the LPSI System failure. Refer to Attachment A for a complete explanation of failure probabilities for CS-NOV-532.
As'such, this proposed change would not:
1.
. Involve a significant increase in the probability-or consequences of an accident previously evaluated. This change merely modifies an existing analysis by increasing the contribution to total system failure probability due to recirculation valve failure to close by
.3%.
Therefore, the change in the probability or consequences of an accident is not a significant increase in the probability or consequences of an accident previously evaluated.
2.
. Create the possibility of a new or different kind of accident from any previously analyzed. Extending the time limitation to two hours does not create the possibility of a new or different kind of accident, since it does not impact the plant analysis methods, operation, or components.
3.
Involve a significant reduction in a margin of safety. This modification does not modify by a significant amount any analysis assumptions, methodologies, or results which affect the ability of the Safety Injection System to perform its intended function during a LOCA event. Thus, this change does not significantly impact the safety margins which currently exist.
United StCtOc Nuclear Rigulstery Commiesien Oct ber 22, 1986 Page 3 DCC 86-167 FYR 86-106 Based on the consideration contained herein, it is concluded that there is reasonable assurance that operation of the Yankee plant, consistent with the proposed Technical Specification will not endanger the health and safety of the public. This proposed change has been reviewed by the Nuclear Safety Audit and Review Committee.
Fee An application fee of $150.00 is enclosed in accordance with 10CFR170.21.
Schedule of Change This change to the Yankee Technical Specifications will be implemented upon Commission approval. A timely review and approval of this submittal to be consistent with our plans for the Cycle 19 refueling would be appreciated.
We trust that you will find this submittal satisfactory; however, should you desire additional information, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY L. H. Heider Vice President / Manager of Operations KJD/jlc COMMot: WEALTH OF MASSACHUSETTS) l
)ss MIDDLESEX COUNTY
)
Then personally appeared before me, L. H. Helder, who, being duly sworn, did state that he is Vice President and Manager of Operations of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing document in the name and on the behalf of Yankee Atomic Electric Company and that the statements therein are true to the best of his knowledge and belief.
o
~
Robert H. Croce hotary Public My Commission Expires August 29,.1991
ATTACHMENT A Evaluation of Technical Specification 4.5.2.b.4 CS-MOV-532 Open BACKGROUND The Low Pressure Safcty Injection (LPSI) recirculation valve, CS-MOV-532, has the-capability to byptos sufficient flow through the 3-inch recirculation line to render the LPSI Syatem ineffective during a Loss of Coolant Accident (LOCA).
The valve, CS-MOV-532, had been designed to close automatically upon a Safety Injection Actuation Signal (SIAS). The Technical Specifications in Section 4.5.2.e.2 provide for verifying that Valve CS-NOV-532 actuates to its correct position on.a safety injection signal at least'once per 18 months
.during shutdown.
During various licensind discussions, the Safety Injection (SI) System valves underwent various changes in method of operation; the most important of which was the spurious valve operation issue of the Station Fire Review. This issue electrically disabled all safeguards system valves in their safeguards position. This action had little effect on the SI System, since all valves are normally in their safeguards position at all times. The only exception to this was CS-MOV-532, which is normally in it safeguard (closed) position, but must be opened to perform weekly LPSI pump flow tests and to mix the SI tank following makeup.
The final solution to the inadvertent valve operation issue was to put dual contactors on all valves required, thereby re-energizing valve position indication and control.while minimizing the possibility of inadvertent valve operation.
CONCLUSION AND BASIS Given that the inadvertent / spurious valve operation issue has been resolved, it was in order to review the very restrictive time limitation on CS-MOV-532.
In line with good surveillance and maintenance procedures, it is desirable to be able to completely test the LPSI System and immediately correct any discrepancies, however minor, such as small packing / seal leaks, etc.
The 30-minute time limit is restrictive to this process and should be corrected to allow for thorough testing following maintenance of the LPSI System without exposing the plant to an unreasonable increase in the probability of LPSI failure on demand. To ensure that maintenance has been properly completed and the system has been properly returned to operable status, completing a full flow test prior to returning the system to service is required.
The LPSI System failure model of the Yankee Nuclear Power Station Probabilistic Safety Study was re-evaluated to determine the effect of increasing the time interval during which CS-MOV-532 is allowed open.
. ATTACHMENT A (continued)
At present, the valve could be open 30 minutes per week for 52 weeks or 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> per year of reactor operation.
The fraction of time that the valve is open is then:
'(26 hr/yr)/(8,760 hr/yr) = 2.97 x 10-3
- to close is 1.25 x 10 grobability int demand for a motor-operated valve falling The mean failure
, from Table 7-2 of the YNPS PSS.
Therefore, the probability that the valve is open and fails to close on demand is:
2.97 x~10-3
- 1.25 x 10-3 = 3.71 x 10 The overall functional failure probability of the LPSI System.from the YNPS PSS is 3.48 x 10-3 Therefore, the allowed opening of CS-MOV-532 clearly is a very small contributor to the overall failure probability of the LPSI System with the present time restriction.
Looking at the sensitivity of LPSI System failure to CS-MOV-532 open time, if we were to increase the allowed open time interval to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the contribution to system failure would still be less than 1%.
Taking a maximum allowed open time of two hours per week yields a fraction of time the valve could be open of:
(2 hr/wk
- 52 wk/yr)/(365 da/yr
- 24 hr/da) = 1.19 x 10-2 Then considering the MOV failure to.close on demand of 1.25 x 10-3 yields a LPSI System failure probability on demand due to CS-MOV-532 failing to close of 1.48 x 10-5 or 0.4% of the tot al system failure probability.
Clearly, increasing the maximum allowable open time of CS-MOV-532 from 30 minutes per week to two-hours per week would have an insignificant effect.
on LPSI System reliability. Based on the above, it is recommended that Technical Specification 4.5.2.b.4 be modified to allow CS-MOV-532 to be open for up to two hours per week to allow for contingencies and ensure that the Low Pressure Safety Injection System is maintained at optimum levels consistent with the plant history.
i 1
- - - -.,, -.. _ -. _ _. - - -.... -., -... - - -.