ML19332C959
| ML19332C959 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 11/20/1989 |
| From: | SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | |
| Shared Package | |
| ML19332C958 | List: |
| References | |
| NUDOCS 8911290232 | |
| Download: ML19332C959 (8) | |
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. Attachment I to Document' Control Desk Letter
'.,a "j' ' ' N;vember 20.--1989 1Page 1 of 2__
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- ATTACHMENT 1 i
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' Technical Specifications Page With Change Indicated a-
. Pace Specification Chance Description 3/4.7-9^
3-47.1.5 Changes 5 second limit to 7 seconds l
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' Attachment'l to Document Control Desk Letter.
s November 20, 1989:
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. SYSTEMS MAIN STEAM LINE ISOLATION VALVES LIMITING CONDITION FOR OPERATION p
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- 3. 7.1. 5 Each main steam line isolation valve shall be OPERABL APPLICABILITY: MODES 1, 2 and 3.
ACTION:-
MODE 1 -
With one main steam itne isolation valve inoperable but open, pow OPERATION may continue provided the inoperable valve is restored OPERABLE: status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />; Otherwise, reduce power to less than or equal to 5 percent of RATED THERMAL POWER within the next 2' hours.
M00ES 2 - With one main steam line isolation valve inoperable, subsequent and 3
' operation in MODES 2 or 3 may proceed provided:
The isolation valve is maintained closed.'
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The provisions of Specification 3.0.4 are not applicable.
L Otherwise, be-in HOT STANDBY within-the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT l
SHUT 00WN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
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SURVEILLANCE REQUIREMENTS L
1 4.7.1.5 Each main steam line is L.
by verifying full closure withi ion valve shall be demonstrated OPERABLE Specification 4.0.5.
econds when tested pursuant to l!
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SUMER - UNIT 1 3/4 7-9 I
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DESCRIPTION OF AMENDMENT REQUEST SAFETY EVALUATION-i b
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, to Document Control Desk letter
.J November 20, 1989.
JPage-2 of 3 DESCRIPTION OF AMENDMENT REQUEST Technical Specification 3/4.7.1.5, " Main Steam Isolation Valves" (MSIV),
surveillance requirement limits the stroke time to a maximum of five seconds when the valves are being tested to satisfy specification 4.0.5.
SCEnG proposes-to change this limit to seven seconds.
The MSIV's are required to be operable to ensure that no more than one Steam Generator will blowdown in the event of a steam line rupture. The closure time of the sbrveillance is required to stay consistent with the assumptions in the accident analyses.
The MSIV's were designed with a closure time specified to.be five seconds;.
this essentially prevents any stroke time degradation from being tolerated since the limit is also five seconds. Because there is no allowance for stroke time degradation, a meaningfull trend of valve performance cannot be established to allow problem analysis or to pre-plan corrective maintenance.
The change to seven seconds would allow this analysis and planning to be possible which in turn would decrease challenges to safety related equipment and reduce the inherent exposures resulting from unnecessary maintenance.
The change to a seven second limit on stroke time would also remain consistent with actuation times assumed in the accident analysis which are as follows:
10 second actuation time-Main Steam Isolation on Reactor Building Pressure, High-2 10 second actuation time-Main steam Isolation on Steam Line Pressure, Low No credit is taken in the Accident Analysis for High Steam Line Flow e
coincident with Low-Low Tavg.
SAFETY EVALUATION The following is an evaluation to determine if the level of safety is compromised by increasing the required stroke time to seven seconds with regards to the ability for the valves to perform their intended functions as assumed in the Accident Analysis.
Engineered Safety Feature Actuation System (ESFAS) response times are used to assure actuation times are maintained within accident analysis. The most limiting ESFAS response time is nine seconds. This revision will not change ESFAS response time limits. Therefore, the assumptions in the accident analyses will not be affected by this change.
The surveillance that will be affected by the revision is performed as part of the Inservice Inspection (ISI) program, as required by Specification 4.0.5.
The Technical Specifications limit for this surveillance, is not part of the ISI requirement and does not alter the requirements for identifying
E.to Document Centrol Desk Letter
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November 20,1 1989 Page 3 of 3 corrective action or declaring failure of the MSIV's. However, the increase to seven seconds provides sufficient margin between allowable stroke times and design stroke times to allow ISI trend analysis to be more useful.
m Therefore,'the-ISI program will not be affected by this change,'even though its results could be enhanced.
Finally, the seven second limit would decrease the probability of cycling the -
plant through a cooldown and subsequent heatup as a result of declaring MSIV's inoperable due to stroke times that are within the accident analysis.
Therefore, as a result of this change, challenges to safety related equipment and the inherent exposure resulting from unnecessary maintenance would be reduced, information for the ISI program could be enhanced and assumptions in the accident-analysis would be unaffected, i
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. November 20.-1989 Pagel1 of 3
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ATTACHMENT 3
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- NO SIGNIFICANT HAZARDS EVALUATION I
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. ' to Document Control Desk Letter
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'N:vember 20, 1989-
'Page 2 of 3 DESCRIPTION OF' AMENDMENT REQUEST
. Technical Specification 3/4.7.1.5, " Main Steam Isolation Valves" (MSIV),
surveillance-requirement limits the stroke time to a maximum of five seconds wh3n the valves are being tested to satisfy spec 1fication 4.0.5.
SCE&G proposes to-change this limit to seven seconds.
The MSIV's are required to be operable to ensure that no more than one Steam Generator will blowdown in the event of a steam line rupture. The closure time of the surveillance is required to stay consistent with the assumptions in the accident analyses.
The MSIV's were designed with a closure time specified to be five seconds; this essentially prevents any stroke time degradation from being tolerated since the limit is also five seconds. Because there is no allowance for stroke time degradation a meaningfull trend of valve performance cannot be established to allow this problem analysis or to pre-plan corrective maintenance. The change to seven seconds would allow analysis and planning to be possible which in turn would decrease challenges to safety related equipment and reduce the inherent exposures resulting from unnecessary maintenance. The change to a seven second limit on stroke time would also remain consistent with actuation times assumed in the accident analysis which are as'follows:
10 second actuation time-Main Steam Isolation on Reactor Building Pressure, High-2 10 second actuation time-Main steam Isolation on Steam Line Pressure, Low No credit is taken in the Accident Analysis for High Steam Line Flow coincident with Low-Low Tavg.
SIGNIFICANT HAZARDS EVALUATION Upon review of the proposed amendment, it has been determined that no significant hazard considerations exist for the following reasons:
L This change does not affect any previously evaluated accidents.
Engineered Safety Feature Actuation System (ESFAS) response times required by Specification 3.3.2 ensures that actuation times are within those assumed in the accident. analyses. The most limiting ESFAS response time requirement is Reactor Building Pressure High-2 response time of nine seconds. The limit being changed does not affect ESFAS response time limits. However, the seven second limit remains consistent with the ESFAS response time requirements; therefore, it also remains consistent with the assumptions of previously evaluated accidents.
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Attachment'3 to Document Control-Desk Letter ne-
' November 20, 1989 Page 3 of 3
-The proposed change does not create the possibility of a new or different' kind of accident from any previously evaluated because the change does not A
alter any plant hardware, and the allowed stroke time addressed in this change is bounded by the actuation time requirement of Specification 3.3.2
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'which assures previously_ evaluated assumptions are met. Therefore, the.
. change remains within the criteria of previously evaluated accidents.
.The proposed change does not involve a significant reduction in the margin of
-safety due to the fact the Technical Specification Basis for the limit is to keep the valve stroke time within the assumptions used in the accident analysis and the new-limit remains within those~ assumptions.
Therefore, based on the above considerations, it has determined that a l
~ ignificant hazard consideration does not exist.
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