ML20083A710
| ML20083A710 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 05/05/1995 |
| From: | Horn G NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20083A714 | List: |
| References | |
| NLS950001, NUDOCS 9505110110 | |
| Download: ML20083A710 (16) | |
Text
t GENERAL OFFICE g
g P.o. BOX 499. COLUMBUS. NEBRASKA 68602-0499 Nebraska Public Power District
" TAM 2/2st" GUY R. IIORN hPresidem, Nuclear (402) 563-5518 NLS950001 May 5, 1995 U.
S.
Nuclear Regulatory Commission Document Control Desk Washington, DC 20555
Subject:
Proposed Change No. 142 to the CNS Technical Specifications Diesel Generator Enhancements Cooper Nuclear Station NRC Docket No. 50-298, DPR-46 Gentlemen:
In accordance with the provisions of 10 CFR 50.90, as required by 10 CFR50.59 (c) (1), the Nebraska Public Power District (NPPD) hereby requests that the Cooper Nuclear Station (CNS) Technical Specifications (TS) be revised as specified in the attachment. This proposed change revises CNS Technical Specifications, specifications 3/4.5.F.1, 3.5.F.2, 3.9.B.1.a/b, 3.9.B.2.a/b/c, 4.9.A.2.a, and associated bases sections.
This proposal consists of three revisions; 1) verifying the redundant diesel generator is operable upon the loss of one diesel generator, and implementing provisions to verify that the operable diesel generator does not have a common cause failure or perform demonstration testing, 2) incorporate the provisions to allow a modified start for the diesel generaters, and 3) removing the requirement that the reactor power level be reduced to 25% of rated power upon loss of both diesel generator units or both incoming power sources (start-up and emergency transformers).
In addition, some rearrangement of information, and rewording of the TS requirements is proposed to enhance usability and alleviate any possible confusion.
These changes are strictly editorial and have no impact on the specifications.
The attachment contains a description of the proposed changes, the attendant 10CFR50.92 evaluation, and the applicable revised Technical Specifications pages in both final and marked up forms for your convenience.
This proposed change has been reviewed by the necessary Safety Review Committees and incorporates all amendments to the CNS Facility Operating License through Amendment 168 issued February 3,1995.
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== .o j \\ NLS950001' Page 2 i May 5, 1995 By copy of this letter and attachment the appropriate State of Nebraska of ficial is being notified in accordance with 10CFR50.91(b) (1). Copies to the NRC Region IV Office and CNS NRC Resident Inspector are also being sent in accordance with 10CFR50.4 (b) (2). should you have any questions or require additional information, please contact me. Sin rely I N R. Horn Vi President, Nuclear GRH/tja:pc-142 Attachment cc: H. R. Borchert Department of Health State of Nebraska NRC Regional Office Region IV Arlington, TX NRC Resident Inspector Cooper Nuclear Station NPG Distribution 1 l i
s.. l NLS950001 Page 3 May 5, 1995 i i STATE OF NEBRASKA ) )ss PLATTE COUNTY ) l l G. R. Horn, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of Nebraska; that he 1 is duly authorized to submit this request on behalf of Nebraska Public-Power District; and that the statements contained herein are true to the best of s knowled e and belief. /JA W D ~ Horn Vice-President, Nuclear Subscribed in my presence and sworn to before me this day of IdlL/ 1995. / j l IIIIIALEIIuneWRInds MLGINF % h 4 Est 34IIIS j NOTARY PUBLIC ~ i I
a. NLS950001 Attachment Page 1 of 12 PROPOSED TECHNICAL SPECIFICATION PAGES FOR DIESEL GENERATOR ENHANCEMENTS Revised naces-120 131 193a (new page) 201 g 121 192 199 202 128 193 200 INTRODUCTION: As discussed below, the Nebraska Public Power District (NPPD) hereby requests that the Cooper Nuclear Station (CNS) Technical Specifications (TS) be amended, as proposed herein. The proposed change will revise specifications 3/4.5.F.1, 3.5.F.2, 3.9.B.1.a/b, 3.9.B.2.a/b/c, 4.9.A.2.a, and associated bases sections. The proposed change consists of three revisions; 1) verifying the redundant diesel generator is operable upon the loss of one diesel generator, and implementing provisions to verify that the operable diesel generator does not have a common cause failure,
- 2) incorporate the provisions to allow a modified start for the diesel generators, and 3) removing the requirement that the reactor power level be reduced to 25% of rated power upon loss of both diesel generator units or both incoming power sources (start-up and emergency transformers).
The changes identified in revision 1 are consistent with the guidance provided in the Standard Technical Specifications (STS) NUREG 1433. The changes identified in revision 2 are consistent with and follows the guidance of Generic Letter 84-15 " Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability." The changes identified in revision 3 are being made to prevent subjecting the plant to an unnecessary transient. QISCUSSION: Proposed revision 1 of this change enhances emergency diesel generator (EDG) reliability by verifying redundant EDG operability rather than demonstrating operability of the redundant EDG, when an EDG will be made or has been determined to be inoperable. The proposed change replaces the requirement to " demonstrate the operable EDG" with the requirement to " verify the operable EDG" in TS 4.5.F.1. Additional wording was included to require that, within 24 hours of an inoperability declaration, station personnel will determine the redundant EDG is not inoperable due to a common cause failure or test the redundant EDG in accordance with surveillance requirement 4.9.A.2.a.1, if it cannot be determined that a common cause failure does not exist. The current three (3) day requirement to demonstrate the operable EDG remains intact but is being changed to read 72 hours for consistency with the STS terminology.
NLS950001 Attachment Page 2 of 12 Elimination of the requirement to immediately demonstrate the redundant EDG is beneficial for the following reasons: 1) overall engine degradation (wear and stress) and the probability of failure due to degradation are reduced and 2) the susceptibility to damage from an electrical grid fault, while the engine under test is running paralleled to the grid, is reduced. Proposed revision 2 of this change enhances EDG reliability by incorporating provisions to allow modified starts of the EDGs in place of the current monthly fast start requirements. This change follows the guidance in Generic Letter 84-15, " Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability" to reduce the number of fast starts on EDGs. The proposed change modifies the monthly periodic testing of the EDG to permit a modified (slow) start of the engine in accordance with surveillance requirement 4.9.A.2.a.1. A hard (fast) start of the EDG will continue to be required every six months in lieu of the modified start. Both the monthly and the every six month test'will require the EDG to be loaded to not less than 50% of rated load for no less than two hours to demonstrate operational readiness. The provisions for logging the starting time for the EDG to reach rated voltage and frequency has been removed from the modified start requirement, but remains intact and is required when the fast start of the EDG is performed in accordance with surveillance requirement 4.9.A.2.a.2. A statement has been added to surveillance requirement 4.9.A.2.a.1, allowing EDG starts to be preceded by an engine prelube prior to starting and warmup period prior to loading. Additionally, a statement has been added to surveillance requirement 4.9.A.2.a.2, allowing EDG starts to be preceded by an engine prelube period. Incorporation of the modified (slow) start provisions and reduction in fast starts for the EDG is beneficial for the following reasons: 1) overall engine degradation (wear and stress) due to fast starts are reduced 2) overall engine wear is reduced and reliability is increased due to allowance of prelube and warmup periods for the EDGs and 3) possibility of introducing test related failures are reduced. Proposed revision 3, of this change deletes the requirement to reduce reactor power level to 25% of rated power. The requirement to reduce plant power to 25% of rated power upon loss both diesel generators and both incoming power sources was established during the licensing process for Cooper Nuclear Station. This
NLS950001 Attachment Page 3 of 12 requirement was instituted on the premise that the reduction in rated power would provide a very stable operating condition upon the loss of either both diesel generators or incoming power sources. In retrospect, this requirement to reduce rated power to 25% forces the plant into an immediate transient. By removing this requirement the plant could remain at the existing power for the short period of time (24 hours) in a more stable condition. In addition, some rearrangement of information, and rewording of the TS requirements is proposed to enhance usability and alleviate any possible confusion. These changes are strictly editorial have no impact, and do not alter technical content or meaning of the specifications. However, the cnly substantial changes to the' requirements of the TS is that which is discussed above. SAFETY CONSIDERATIONS: Proposed Revision 1: TS section 4.5.F.1, presently requires that "When it is determined that one diesel generator is inoperable... the operable diesel generator shall be demonstrated to be operable immediately and every three days thereafter." The TS requirement for the immediate testing of the operable diesel generator was based on an earlier NRC staff position. The intent of the prior specification was to provide positive demonstration that a loss of safety function had not occurred. To satisfy the current TS requirement, the operable EDG must be taken out of service to demonstrate operability through supplemental testing. The detrimental effects of testing exceed the benefit derived from any added assurance of operability the test provides. Supplemental testing results in both an increased probability of equipment failure due to unnecessary wear and possible damage to the EDG due to electrical grid fault. The requirement for the immediate testing increases the risk of losing the remaining operable diesel generator. Industry operating experience has demonstrated that testing EDGs, when one train is operable, is not necessary to provide assurance of system operability. A failure of a different diesel generator does not reduce the reliability of an otherwise operable diesel generator. The requirement to immediately demonstrate the operability of an otherwise operable diesel generator, once a determination has been made that no common cause failure exists, has no overall effect on the design or performance characteristics of the EDG engine. Barring a common cause failure, the current TS surveillance testing schedule of demonstrating operability every three days (72 hours) when one DG is inoperable provides adequate confidence that the operable diesel generator is capable of performing its intended safety function. Therefore, the ability of the diesel generator to perform its design function is maintained.
i I NLS950001 Attachment Page 4 of 12 i The proposed change to section 4.5.F.1 allows an EDG to be out of service without requiring supplemental immediate testing of the redundant EDG. Station personnel are required to determine within 24 hours if the redundant diesel generator has been made inoperable by a common cause failure. The redundant EDG will remain in-service during the entire period of inoperability of the out-of-service EDG. If a common cause failure cannot be ruled out, the redundant diesel generator will be tested in accordance with the surveillance requirements of TS section 4.9.A.2.a.1 to ensure operability. This proposed revision reflects current NRC staff position on testing redundant safety equipment and is consistent with recent NRC safety evaluations on utility dockets concerning this topic. This change is also compatible with plant operating experiences and follows the guidance provided in the staff approved Standard Technical Specifications NUREG-1433, dated September 1992. Proposed Revision 2: TS section 4.9.A.2.a, presently requires that "each diesel generator shall be started....once each month to demonstrate operational readiness." The TS requirement for the monthly testing of the diesel generator does not allow for a modified " soft start" of the EDG's. This TS requirement is part of the original license for Cooper Nuclear Station and was based on earlier NRC staff position to have all EDG starts from the cold ambient condition. Since that time, the NRC staff has revised their position on the use of and number of hard starts the EDG should be subjected to. The NRC has endorsed the reduction of fast starts for EDG in Generic Letter 84-15, " Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability" By substituting a modified " slow start" for the currently required monthly fast start test, EDG engine wear will be reduced and the engine would still be tested adequately. A modified start is considered a start in which the engine is prelubricated, has prewarmed oil and water circulating and reaches speed and load on a prescribed schedule that is selected and is consistent with the manufacturers recommendations to minimize stress and wear. The test demonstrates the ability of the diesel generator to start reliably, and to carry the required load. The capabilities of the cooling system and other support systems are also demonstrated. The fast start test will be performed every six months in lieu of the modified " slow start." During this test the engine will be prelubricated. The " fast start" demonstrates the ability of the engine to start within the time required, and reach rated voltage and frequency as required in the accident analysis. In addition, both the monthly and the six month test will require the EDG to be loaded to not less than 50% of rated load for no less than two hours. Testing at Cooper Nuclear Station has shown that operation
1 NLS950001 Attachment Page 5 of 12 of the EDG for a two hour period ensures that stable EDG conditions are achieved. The proposed revision of the CNS TS allows a modified " slow start" for most monthly periodic tests, and only requires a fast start once every l six months. Reducing the number of fast starts has safety and operational benefits. Fast starts have been demonstrated to be a contributor to engine wear and premature failure. The revised testing will still demonstrate that the EDG's are ready to perform their safety function, and will increase the reliability and availability of the EDG's. In addition, allowing planned testing to be preceded by a prelube period and some planned testing to be preceded by a warmup period reduces engine stress and wear. This change will bring CNS's testing requirements for EDG into conformance with the latest NRC guidance (Generic Letter 84-15) to reduce the number of hard " fast starts." Proposed Revision 3: TS sections 3.5.F.2 and 3.9.B.1.b, presently require that ... reactor power level is reduced to 25% of rated power..." during any period when both diesel generators are inoperable or when incoming power is not available from both the start-up and emergency transformers (both failed). The requirement to reduce plant power to 25% of rated power upon loss of both diesel generators or both incoming power sources was established during the licensing process for Cooper Nuclear Station. This requirement was instituted based on the premise that the reduction in rated power would provide a very stable operating condition upon the loss of either both of the diesel generators or incoming power sources. In retrospect, this requirement to reduce rated power to 25% forces the plant into an immediate transient. This requirement to reduce power level subjects the plant to an immediate transient with no safety benefit. This requirement also forces the plant into a less stable condition. This is true because the plant is considerably more stable if it were to remain at the existing power level instead of subjecting it to a transient. Therefore, from an operational standpoint the plant is more stable by remaining at the existing power level for a short period of time. There is no safety impact from the removal of this requirement, rather removal of this requirement would not force CNS to subject the plant to a transient caused by a reduction in power to 25% of rated power. By removing this requirement the plant could remain at the existing power for the short period of time (24 hours) and remain in a much more stable operating condition. The time line of 24 hours for repair or declaration to operable status (of either EDG or offsite power source) is not being changed. Additionally, the loss of both offsite power sources condition becomes more restrictive by requiring a shutdown instead of notification within 24 hours.
) i. NLS950001 Attachment Page 6 of 12 DESCRIPTION OF CHANGES: NPPD requests that the CNS Technical Specifications Sections 3/4.5.F.1, 3.5.F.2, 3/4.5.F Bases, 3.9.B.1.a, b&c, 3.9.B.2.a & b, 4.9.A.2.a, and the 3/4.9 Bases sections be revised to incorporate EDG verification, common cause failure, modified start allowances, and the removal of the requirement to reduce rated power to 25% upon loss of both diesel generators or incoming power sources. A mark-up of the affected CNS Technical Specifications pages are provided in Appendix A, and the new affected CNS Technical Specifications pages are provided in Appendix B. The specific changes proposed to the CNS Technical Specifications are detailed below: Page 120 - Revise Specification 3.5.F.1, to include the requirements of 4.5.F.1 and revise this specification to read the " remaining" requirements of 3.9.A.1.are met. Revise and reformat Surveillance Requirement 4.5.F.1, to verify the redundant diesel generator and associated subsystems are operable immediately and daily thereafter upon declaration of inoperability of one diesel generator. Add requirement to determine that the operable diesel generator is not inoperable due to common cause failure or perform operability surveillance (SR 4.9.A.2.a.1), with a completion time of 24 hours. Reword requirement to demonstrate operable diesel generator from every three days to every 72 hours to be consistent with Standard Technical Specifications (STS) terminology. Page 121 - Revise Specification 3.5.F.2, by removing the requirement that the reactor power level is reduced to 25% of rated power. Revise this specification to read the " remaining" requirements of 3.9.A.1.are met. Page 128 - Revise Bases Section 3.5.F, to include an explanation of I what is meant by the remaining requirements of 3.9.A.1 which is referenced in LCO 3.5.F.1. In addition, a sentence is added to reference the location of the explanation of the 4.5.F.1 requirements. Finally, this page revision removes the sentence "The reduction of rated power to 25% will provide a very stable operating condition." Page 131 - Revise Bases Section 4.5.F, to include an explanation of what is meant by the requirements of 4.5.F.1. This explanation includes a description and definition of " verification", " completion times", and " demonstration".
NLS950001 p Attachment Page 7 of 12 Page 192 - Revise Specification 3.9.B.1.a/b, to change demonstrate DG operability to " verify", remove requirement that the reactor power level is reduced to 25% of rated power, and'NRC notification outlining restoration plans. i Revise Specification 3.9.B.1.b, to include the requirement that operation in this condition is only permissable during the succeeding 24 hours. Page 193 - Revise Specifications 3.9.B.2.a and 3.9.B.2.b, to include the words "the remaining requirements of" specification 3.9.A.1 "are" satisfied. Revise Specification 3.9.B.2.c, discussing actions required when EDG and power source is inoperable. Additionally, remove requirement to notify NRC of our plans for restoration. t Revise Specification 4.9.A.2.a by splitting this requirement into two separate requirements for testing the diesel generators. Specification 4.9.A.2.a.1 describes the monthly testing requirements including the modified start and prelube and warmup periods. Specification 4.9.A.2.a.2 describes the six month testing requirement including prelube and logging criteria. Page 199 - Revise the 3.9 Bases section by correcting two errors. In the sixth paragraph breakers should read "line breaks". In the seventh paragraph correct the referenced specification to "3.9.B.2.d." Page 200 - Revise the 3.9 Bases section by correcting the referenced specification to "3.9.B.2.e" in the top paragraph. Revise the 4.9 Bases section by including an explanation of the new 4.9.A.2.a.1, and 4.9.A.2.a.2 surveillance requirements. Pages 201 - There are no changes to these two pages other than the & 202 relocation of existing information due to the additional bases clarifications in support of this change. I l f l l
4 NLS950001 Attachment Page 8 of 12 NO SIGNIFICANT HAZARDS EVALUATION: 10 CFR 50. 91 (a) (1), requires that licensee requests for operating license amendments be accompanied by an evaluation of significant hazards posed by the issuance of the amendment. NPPD has reviewed the proposed changes in accordance with 10CFR50.92 and concludes that the changes do not involve a significant hazards consideration (SHC). The basis for this conclusion is that the three criteria of 10CFR50.92 (c) are not compromised. The proposed changes do not involve a SHC because the changes would not: 1. Involve a significant increase in the probability or consequences of an accident previously analyzed. ProDosed Revision 1: This proposed revision serves to ensure that an emergency diesel generator is always available to perform on demand and that lowering the number of demands to demonstrate operability reduces the probability of equipment failure. The required action no longer requires the redundant emergency diesel generator to be demonstrated operable immediately. Therefore, this requirement has been deleted from TS 4.5.F.1. The proposed change includes provisions to determine if the redundant diesel generator has been made inoperable by a common cause failure or perform a demonstration test. The redundant emergency diesel generator will remain in service during the entire period of inoperability of the out of service emergency diesel generator. If a common cause failure cannot be ruled out, the redundant diesel generator will be tested in accordance with the surveillance requirements of TS section 4.9.A.2.a.1 to assure operability. Since this proposed revision does not affect the design or negatively affect the performance of the diesel generators, the change will not result in an increase in the consequences or probability of an accident previously analyzed. This proposed revision will increase diesel generator reliability and availability, thereby increasing overall plant safety. ProDosed Revision 2: This proposed revision only affects emergency diesel generator periodic testing. The diesel generators are not accident initiators and the method of testing the diesel generators cannot initiate an accident and therefore will not increase the probability of an accident. This change to the diesel generator testing method does not impact any Updated Safety Analysis Report (USAR) safety analysis. The proposed surveillances will still provide assurance that the diesel generators are available to mitigate the consequences of accidents previously evaluated. Thus the consequences of an accident previously evaluated are not increased.
... ~ . ~. ..'^ NLS950001' Attachment Page 9 of 12
- The revised periodic testing will-still demonstrate that the.
emergency diesel. generators arefready to perform their safety function. An overall improvement.in diesel. engine reliability and availability can be gained by performing diesel generator starts for surveillance ~ testing using engine prelubes, warmups and other manufacturer recommended practices to reduce engine stress and' wear. Since.this. proposed revision does not affect the design or i negatively affect the performance of the diesel generators, the change will not result in an increase in the consequences or probability of an accident previously analyzed. This proposed l revision will increase diesel generator reliability, thereby increasing overall plant safety. 1 i Proposed Revision 3: This proposed revision does not affect the operation of the emergency diesel generators or the incoming power sources (start-up and emergency transformers). Both the diesel generators and the incoming power sources function to mitigate the consequences i of postulated accidents. As such, removing the requirement to i reduce power level upon the loss of both redundant components in either of these systems does not create an increase in the probability of an accident. By eliminating this requirement, the potential for plant transients during power reduction to 25% are also eliminated. Eliminating this requirement will not increase O the consequences of a postulated accident because the redundant components will remain available. Additionally, the loss.of both _ offsite power sources condition becomes more restrictive by. I requiring a plant shutdown instead of notification within 24 hours. The proposed changes do not alter the conditiens or assumptions in any of the Updated Safety Analysis Report (USAR) accident. analyses. Since the USAR accident analyses remains bounding, the radiological consequences previously evaluated are not adversely affected by the proposed changes. Therefore, no significant-increase in the probability or consequences of an accident previously analyzed would occur Tha t proposed rearrangement of information, and rewording of some the TS requirements are included to enhance usability and alleviate any possible confusion. These changes are strictly editeirial have no impact, and do not alter technical content or mean.ng of the specifications. These editorial changes do not j involve a significant increase in the probability or consequences of t.n accident previously analyzed. i F t
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Page 10aof_12 i ' 2. Create the possibility of a new or different kind of accident ~ from any previously analyzed. Procose'd Revision 1: ' Accidents involving loss of off-site power and single failure a 'have been previously evaluated,'and this proposed change doesinot J impact any of:those assumptions. This proposed revision does not introduce any new mode of plant operation or new accident precursors,. involve any. physical-alterations to plant configurations,~ or make changes to system _setpoints which could -initiate a new or different kind of accident. ' Operation of the, I facility in accordance_with the proposed revised changes does'not create the possibility of a new or different kind of accident l from any previously evaluated. Proposed Revision 2: i This proposed revision only affects emergency diesel generator periodic testing. The diesel-generators are not accident initiators ~and the method of testing the-diesel generators cannot. initiate an accident. This revision does not relieve the j' operation of the diesel generator from existing' requirements and the diesel generators remain bounded by the. assumptions.in the USAR accident analysis. The method of testing provides assurance that the diesel generators are available when needed. The i proposed revision does not involve any changes in setpoints, plant equipment, plant operation, protective functions, or the q design basis of the plant. Therefore, a change in the method of starting the diesel generators during periodic testing would not i create a different kind of accident than previously evaluated. t Proposed Revision 3: This proposed revision does not add or change any equipment or j logic, nor do the changes associated with this revision alter any i system operability requirements. The proposed changes for this revision do not introduce any new failure modes for any plant i system or component important to safety nor has any new limiting i failure been identified as a result of the proposed revision. I Since there are no changes to the function, or operation offany system, equipment, or component, the possibility of a new or different kind of accident is not created. The proposed rearrangement of information, and rewording of j some the TS requirements are included to enhance usability and alleviate any possible confusion. These changes are strictly l editorial have no impact, and do not alter technical content or meaning of the specifications. These editorial changes do not create the possibility of a new or different kind of accident l from any previously analyzed.
(I CE l Ji ,3+ h} NLS950001 Attachment ~ i Page 11 of 12 d; -l 1 -3.. . Involve. a significant reduction in the margin of safety.' 1: Proposed' Revision _11 This proposed revision does not result in an overall reduction l ' n the margin of safety. The reduction in margin going from lL i "immediately" testing an operable diesel generator to 24 hours'to 1 determine no common cause, is offset by the increase in margin h resulting'from increased dies ~1 generator reliability and availability, associated with implementing the vendor recommendations for testing and not exposing the diesel generator ~ to potential grid disturbances when a diesel generator is found 1 to be inoperable. No physical modification to the plant or change in the procedurally prescribed operator accions result l from the proposed changes associa ed with this revision. i Operation of the facility in accordance with the proposed l revision does not involve a significant reduction in a margin of I safety. Proposed Revision 2: [ I This preposed revision is made to increase the reliability and [ availability of the emergency diesel generators thus enhancing l the safety of the plant. Changing the way periodic testing of j the diesel generators is conducted does not involve a reduction i in safety. The test still demonstrates the ability of the diesel generator to start within the time required, and reach rated voltage and frequency as required in the accident analysis. The .t test also demonstrates the ability of the diesel generator _to l start reliably, carry the required load, and ensures the 5 capabilities of the cooling system and other support systems are operable. Therefore, assurance that the diesel generators operate within the limits determined to be acceptable continues l to be provided. Implementing manuf acturer's recommendations to minimize stress and wear of the diesel engine does not involve a significant reduction in the margin of safety, but rather enhances safety. j Procosed Revision 3: This proposed revision deletes the requirement to reduce j reactor power level to 25% of rated power upon the loss of either 3 both diesel generators or both incoming power sources. The elimination of this requirement will allow the plant to maintain the existing power level rather than subject the plant to an unnecessary transient. Maintaining the plant at the existing power level provides a more stable operating environment. The equipment and components of the diesel generators or the incoming power sources are not impacted in any way as a result of the proposed revisions. The margin of safety for the diesel generators and the incoming power sources are not significantly reduced since these systems are not altered in any way, and will continue to be surveillance tested as required. Assurance of
T: ' NLS950001 Attachment Page 12-of 12 . operability is provided by the normal, scheduled surveillances which have been established at a sufficient interval to provide reasonable assurance of operability. Therefore, the proposed changes do not involve a'significant reduction in the margin of safety. The proposed rearrangement of information, and rewording of some the TS requirements are included to enhance usability and alleviate any possible confusion. These changes are strictly editorial have no impact, and do not alter technical content or meaning of the specifications. These editorial changes do not involve a significant reduction in the margin of safety. CONCLUSION: NPPD has evaluated the proposed changes described above against the criteria of 10CFR50.92(c) in accordance with the requirements of 10CFR50. 91(a) (1). This evaluation has determined that Proposed Change No. 142 to the CNS Technical Specifications will n2t1 1) involve a significant increase in the probability or consequences of an accident previously evaluated; 2) create the possibility for a new or different kind of accident from any accident previously evaluated; or 3) create a significant reduction in the margin of safety. Therefore, NPPD. requests NRC approval of proposed change No. 142 to the CNS Technical Specifications. 9
O + e l I r L t APPENDIX "A" i 1 ,}}