ML20237E082

Forwards Info in Support of Proposed TS Amend Related to EDG Allowed AOT as Listed,Per NRC 980319 Request.Reformatted TS 3.9.A Encl

ML20237E082
Person / Time
Site:	Pilgrim
Issue date:	08/24/1998
From:	Ted Sullivan BOSTON EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20237E083	List: ML20237E082 ML20237E085
References
BECO-2.98.122, TAC-M95277, NUDOCS 9808280239
Download: ML20237E082 (10)

Text

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G Bostms Edison Pilgrim Nuclear Power Station 10 CFR 50.90 Rocky Hiil Road

. Plymouth, Massachusetts 02360 T.A. Sullivan General Manager Production and Station Director August 24, 1998 BECo Ltr. #2.98.122 i

US Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Docket No. 50-293 License No. DPR-35 Supplement to Emergency Diesel Generator Allowed Outaae Time Technical Specification Amendment (TAC No. M95277)

Boston Edison Company (BECo) is providing the attached information in support of the proposed technical specification (TS) amendment related to the emergency diesel generator l (EDG) allowed outage time (AOT), as follows. i 1

1. Attachment A provides information concerning' the proposed Configuration Risk l Management Program. On March 19, 1998, the NRC telexed elements of a Configuration Risk Management Program (CRMP) and requested BECo incorporate this program as a requirement for approving the proposed TS amendment for extending the EDG AOT to 14 days. Accordingly, CRMP is proposed as part of the EDG AOT TS change.

2. Attachment B provides the revised No Significant Hazards Consideration determination pursuant to 10- CFR 50.92(c). This determination supersedes the previous determinations included ln BECo letter Nos.96-040, dated April 25,1996, and 98-030, dated March 26,1998.

3. Attachment C is a complete package of the proposed EDG AOT TS amendment for NRC approval. This includes the following:

. Verification of the station blackout diesel generator operability before entering into an extended EDG AOT,

. A 48-hour LCO when one EDG and the shutdown or startup transformer are inoperable as specified in the proposed TS 3.9.B.4, and b . A proposed Configuration Risk Management Program.

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9808280239 989824 ..

Il PDR ADOCK 05000293' P PDR; L

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l In addition, we have included reformatted TS 3.9.A which became necessary due to {

change to TS 3.9.B. The reformatted TS 3.9.A is an administrative change. l l

Should you have any questions regarding this letter, please contact Walter Lobo at (508) )

830-7940. l 1 4 s

.A. Sullivan Commonwealth of Massachusetts)

Country of Plymouth ) f i

Then personally appeared before me, T.A. Sullivan, who being duly sworn, did state that he '

is General Manager Production and Station Director of Boston Edison Company and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Boston Edison Company and that the statements are true to the best of his knowledge and belief.

i My commission expires: bMob otoc A #17 b  !

~/ DATE [

NOTAR[ PUBLIC Attachment A: Discussion of the Configuration Risk Management Program (CRMP)

Attachment B: Revised No Significant Hazard Consideration Determination Attachment C: Revised T.S. Pages and Bases Applicable for EDG AOT wgl/edgermp. doc cc: Mr. Alan B. Wang, Project Manager Mr. Robert Hallisey Project Directorate 13 Radiation Control Program Office of Nuclear Reactor Regulation Center for Communicable Diseases Mail Stop: OWFN 14B20 Mass. Dept. of Public Health .

1 White Flint North 305 South Street j 11555 Rockville Pike Jamaica Plain, MA 02130 1

Rockville, MD 20852 1 U.S. Nuclear Regulatory Commission Mr. Peter LaPorte, Director Region i Mass. Energy Management Agency 475 Allendale Road 400 Worcester Road i King of Prussia, PA 19406 P.O. Box 1496 i Framingham, MA 01701-0313 l

Senior Resident inspector ) '

Pilgrim Nuclear Power Station J

ATTACHMENT A '

Discussion of the Configuration Risk Management EDG AOT Technical Specification Amendment (TAC No. M95277)

References

1. Boston Edison Company (BECo) Letter No.96-040, " Proposed Technical Specification Changes," dated April 25,1996.

2. BECo Letter No.96-080, " Response to Request For Additional Information Regarding Emergency Diesel Generator Allowed Outage Time Technical Specification Change (TAC No. M95277)", dated September 5,1996.

3. BECo Letter No.97-082, " Supplement to Emergency Diesel Generator Allowed Outage Time Technical Specification Change (TAC No. M95277)", dated August 8,1997.

4. BECo Letter No.98-030, " Supplement to Emergency Diesel Generator Allowed Outage Time Technical Specification Change (TAC No. M95277)", dated March 26,1998.

5. BECo Letter No 98-103, " Supplement to Emergency Diesel Generator Allowed Outage Time Technical Specification Change (TAC No. M95277)", dated July 31,1998.

Backaround 4 BECo filed a request (Ref.1) for a TS amendment to extend the current emergency diesel generator (EDG) allowed outage time (AOT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. Subsequently, four other letters (Refs. '. 4, and 5) were submitted in response to NRC requests for additional information. On Mae 19, 1998, the NRC telexed elements of a Configuration Risk Management Program (CRMP) and requested that we add CRMP to our proposed technical specifications amendment, contingent upon approval of the extended AOT. The proposed CRMP is discussed together with the determination of No Significant Hazards Consideration (NSHC) for the EDG AOT change. The TS page included in reference 5 is revised and a complete EDG AOT TS change package is included with this submittal.

Configuration Risk Manaaement Proaram BECo proposes to incorporate a Configuration Risk Management Program (CRMP) into the PNPS TS as indicated by the attached TS pages. The PNPS CRMP will proceduralize the use of a risk assessment of planned and unplanned equipment maintenance activities associated with technical specification structures, systems, and components (SSCs) for which a risk-informed allowed outage time has been granted (i.e., the EDGs). Program elements will be as follows:

CRMP Element a. Provisions for the control and implementation of a Level 1, at-power, internal evonts, PRA-informed methodology. The assessment shall be capable of evaluating the applicable plant configuration.

l l (Additionally, observations described in NRC Inspection Report 98-04 as they relate to the CRMP are placed in perspective. Follow-up NRC questions on uncertainty and common cause failures are also addressed.)

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RESPONSE: i

. The CRMP integrates the capability of the Equipment Out Of Service (EOOS) risk monitor, I which uses a Level 1, at-power, internal events, PRA-informed methodology. EOOS facilitates planning and scheduling strategies to maximize equipment performance, reliability, and availability during the EDG extended AOT.

A Level 1 PRA supports the determination of Core Damage Frequency (CDF). A Level 2 PRA supports the determination of Large Early Release Frequency (LERF). The PNPS Level 1, at-power, internal events PRA forms the basis for the PNPS EOOS. The PNPS Level 1 model includes input to containment system event trees (see section 4.3 of the PNPS iPE submittal, BECo letter 92-114 dated September 30, 1992). This allows containment system dependencies to be identified by EOOS.

The scope of SSCs in the CRMP will include all SSCs modeled in the PRA as well as those

.SSCs deemed risk significant by the Maintenance Rule Expert Panel not modeled in the PRA.

As not all Maintenance Rule in-scope SSCs are modeled in EOOS, the EOOS calculation is only one tool available for assessing risk. Although the scope of the CRMP is as described, the portion of CRMP to which TS apply is limited to the SSCs for which risk-based AOTs have been granted. Specifically, the CRMP must be used whenever the 14 day EDG LCO is entered.

PNPS uses the EOOS model to provide risk calculations of plant configurations. It allows plant i personnel to calculate risk based upon inoperable equipment combinations. For any identified plant configuration of SSCs modeled in the PRA, EOOS provides risk importance measures associated with the unavailable equipment as well as those SSCs still in service. This portion of the process was reviewed in detail by the NRC during the Maintenance Rule inspection (IR 98-04 dated June 29,1998) with favorable results.

In addition to the previously mentioned risk significant SSCs, the CRMP will include provisions to consider other applicable risk significant contributors such as Level 2 issues and external events, qualitatively or quantitatively. The Level 2 issues relate to those accident sequences which lead to a large early, unscrubbed release from containment (LERF). Accident sequences of concern are relatively fast-acting such as ATWS (20%) and loss of high pressure injection with either failure to depressurize (TOUX-type sequences - 57%) or loss of low pressure injection (TOUV type sequences - 23%). The EDGs are marginal contributors to TOUV type sequences and do not contribute to ATWS and TOUX-sequences. Therefore, maintaining the availability of low pressure injection systems at an optimum during the EDG AOT will adequately address Level 2 issues.

l External events of concern include severe weather and fire. The CRMP will ensure appropriate attention is placed on scheduled maintenance activities when severe weather approaches or when activities are planned for areas with high fire hazards. Although not l

specifically included in the CRMP, the risk importance measure capability of CRMP can be used to identify key equipment to protect.

As always, the qualitative assessment of the entire work scope by trained and experienced personnel will continue to play a key role in assuring scheduled work does not place the plant in an unsafe condition.

By procedure, PNPS will require a risk assessment prior to removing equipment from service for planned maintenance activities. The requirement to perform a risk assessment following unplanned equipment failures will also be proceduralized. This requirement will apply to SSCs within the scope of the CRMP.

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The PRA is periodically updated in accordance with engineering design guide (SB03) to account for modifications to the plant as well as plant equipment performance. The EOOS l program is updated following update of the PNPS PRA model.

Resolution of NRC Observations Related to CRMP (IR 98-04) l BECo's (a)(3) Periodic Assessment Report, Section 6.0, " Review of the Removal of Equipment from l Service, " identified that not all sources of risk are identified, not all risk significant SSCs are included, and there was noformalprocessfor consideration of riskfrom emergent work. The report also noted 1 that EOOS did not address reactivity monitoring and control, primary containment, external initiators l such as weather, and internalinitiators such as other work in the area, the condition of the redundant {

train if applicable, and the impact on the operators ofall the activities being performed. 1 As discussed above, the scope of the CRMP program will include all risk significant SSCs as well as all potential risk contributors including external events and Level 2 issues. Additionally, ,

emergent work considerations after entering a risk-based LCO will be covered by the CRMP. l All reactivity monitoring and control systems having active functions to mitigate plant accidents  !

and/or transients are explicitly modeled in the Level 1 PRA and, therefore, are in the EOOS l model. Additionally, adverse weather conditions are modeled in EOOS by increasing the loss  !

of offsite power frequency.

Uncertainty Analysis The PRA study fo- the EDG AOT extension assumed each EDG would be out for the fut 14 day time period. This in itself represents a sensitivity study since PNPS Procedure 1.2.2 Attachment 11 normally permits only 50% of the AOT to be used for planned maintenance.

The 14 day unavailability time is in addition to the historical EDG unavailability captured in the PRA database. No other additional quantitative uncertainty analysis was performed as part of this submittal. Sensitivity analyses on a number of assumptions were performed on the original PRA as part of the IPE submittal.

Common Cause A multiple Greek letter methodology was used in the PRA analysis as referenced in the IPE submittal, section 2.5.1.2. No adjustments were made to any common cause failure events for this analysis. The analysis conservatively assumed that even with one EDG unavailable, a common cause failure from the idled EDG contributed to core damage.

The two EDGs and the SBO-DG were treated as a group of three similar SSCs. The analysis derived a beta factor of 6.7E-2 and a gamma factor of 2.4E-2 for diesel fail-to-run and a beta factor of 2.2E-2 and a gamma factor of 6.7E-2 for diesel fail-to-start. These factors were derived from EPRI NP-3967 Table 3-7 as discussed in Appendix A of the IPE submittal.

CRMP Element b. Provisions for performing an assessment prior to entering the LCO Action Statement forpreplanned activities.

RESPONSE

The PNPS work control schedule identifies preplanned entries into technical specification action statements associated with a risk-informed AOT. EOOS provides a risk assessment of the proposed plant configuration prior to placing the plant in that configuration. The on-line work scheduling program is uploaded into EOOS on a weekly basis to allow for weekly risk l

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profile calculations based on the scheduled work. The calculated risk importance measures of i available and unavailable SSCs identify the risk significant configurations while in the action statement.

This process is already described in PNPS procedure 1.5.21, ' Work Control Scheduling Activities and Guidelines". Also, procedure 1.2.2, " Administrative Ops Requirements",

Attachment 11, contains the following guideline: " Prior to releasing equipment from service, the NWE shall evaluate plant conditions to ensure that concurrent activities will not  ;

compromise plant safety or performance. Prior to entering an active LCO for maintenance,  !

the NWE will review and approve the LCO-Maintenance Planning Checklist." Therefore, the current process for assessing risk associated with pre-planned rnaintenance activities adequately addresses this element. However, BECo retains the authority to revise the specific manner in which this element of CRMP is implemented. For example, other procedures may be revised or created in the future to more effectively implement this element of CRMP.

CRMP Element c. Provisions for performing an assessment after unplanned entry into the LCO Action Statement.

RESPONSE

A risk assessment will be performed following all unplanned entries into technical specification action statements associated with a risk-based AOT. Judgment will be used to determine when the risk assessment will be performed and which risk assessment tool will be used (e.g.,

qualitative or quantitative). This requirement will be proceduralized.

CRMP Element d. Provisions for assessing the need for additional actions after the discovery of additional equipment out of service conditions while in the LCO Action Statement.

RESPONSE

If any additional SSCs become unavailable while in an EDG technical specification action statement, a risk assessment will be performed in a time frame consistent with our corrective action program. This requirement will be proceduralized and will be subject to the same judgment identified in our description of element "c".

CRMP Element e. Provisions for considering other applicable risk significant contributors such as Level 2 issues and external events, qualitatively or quantitatively.

RESPONSE

The CRMP will have provisions to consider as part of planned maintenance other applicable risk significant contributors such as Level 2 issues and external events, qualitatively or quantitatively. For example, salt spray concerns are reflected in the initiating event frequency for loss of offsite power. Also, some existing procedures already prohibit taking high risk-significant systems out of service when severe weather conditions approach. The discussion of element "a" includes more information on this issue.

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ATTACHMENT B REVISED NO SIGNIFICANT HAZARD CONSIDERATION DETERMINATION Description of amendment reauest: The proposed amendment would revise Technical Specifications (TSs) and associated Bases Section for TSs 3/4.5.F.1, " Core and Containment Cooling systems", TSs 3.9.B.1 and 3.9.B.4, " Auxiliary Electrical System", and add Configuration Risk Management Program in TS 5.5, " Programs and Manuals" of Section 5.0  ;

" Administrative Controls".  !

TS 3.5.F.1 is revised to extend the allowed outage time (AOT) for the emergency diesel generators (EDGs) from the currently allowed 3 days to 14 days. TS 4.5.F.2 is added to ,

confirm the station black out diess! generator (SBO-DG) is operable for extending the EDG l AOT from 3 days to 14 days. The actions include confirmation that SBO-DG has been i demonstrated operable within the preceding 7 days before extending the AOT from 3 days to I 14 days or to perform a surveillance within 3 days of an EDG inoperability to demonstrate that the SBO-DG is operable. The SBO-DG is a non safety-related, manually started,2000 KW l generator and is not a qualified replacement for an EDG. An additional action is added to verify normal breaker configuration to ensure the SBO-DG is capable of energizing the safety bus associated with the inoperable EDG. These actions assure one EDG and the SBO-DG are operable during an extended EDG AOT.

TS 3.9.B.1 is also split into two individual AOTs, one for the startup transformer (SUT) and one for the shutdown transformer (SDT). The AOT for SDT remains at 7 days (TS 3.9.B.1.b),

and the AOT for the SUT is reduced from 7 days to 3 days (TS 3.9.B.1.a) based upon the probabilistic safety assessment (PSA) results. TS 3.9.B.4 is revised to specify AOTs for the combination of an inoperable EDG and an inoperable SUT or SDT. The AOT for simultaneous inoperability of an EDG and SUT or SDT is 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> (TS 3.9.B.4.). These changes in the AOTs for the SUT and SDT are proposed based upon their contribution to risk in relation to the EDG 14-day AOT risk assessment analysis. Adding additional system operability requirements to TS 3.9.B.4 provides a positive measure to prevent entry into or remain in the 14-day EDG AOT, if the required offsite power supplies become unavailable.

TS 5.5 is revised by adding TS 5.5.7 " Configuration Risk Management Program (CRMP)".

This is an administrative program, which provides a proceduralized risk-informed assessment to manage the risk associated with equipment inoperability. The program applies to technical specification structures, systems, or components for which a risk-informed allowed outage time has been granted. The program will require a risk assessment of planned and unplanned plant configurations resulting from inoperable EDGs. This is considered an administrative change to the technical specifications since no technical changes are proposed.

TS 3.9, " Auxiliary Electrical System" and TS 3.9.A, " Auxiliary Electrical Equipment" are reformatted to look alike TS 3.9.8 due to proposed changes in TS 3.9.B. The reformatting of TS 3.9. and 3.9.A is an administrative change.

l Basis for proposed no significant hazards consideration determination: The Code of Federal Regulations,10 CFR 50.91(a), requires licensees requesting an amendment to provide an analysis, using the standards in 10 CFR 50.92, that determines whether a significant hazards consideration exits. As required by 10 CFR 50.91(a), Boston Edison Company provides the following analysis to determine no significant hazards consideration in accordance with 10 CFR 50.92.

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1. The proposed amendment does not involve a significant increase in the probability l or consequences of an accident previously evaluated.

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' Operation of Pilgrim Nuc! ear Power Station in accordance with the proposed license i amendment will not involve a significant increase in the probability or consequences of an '

accident previously evaluated because of the following: l An Individual Plant Examination (IPE) for Internal Events was submitted to the NRC in response to Generic Letter 88-20 in September 1992. The supporting probabilistic safety analysis (PSA) model was updated as described in BECo letter 95-127, dated December 28, 1995. The updated PSA model was used to quantify the overall impact of the proposed EDG 14-day AOT on core damage frequency. Part lli of BECo Letter No. 2.96.040 provides the results of a comprehensive PSA of the impact of the proposed AOTs for the EDGs and SUT and SDT. As shown in Part Ill, there is no significant increase in risk due to the proposed change. Thus, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

The existing specification 3.9.B.1 is separated into two segments (a and b) because of the proposed different AOTs for the SUT and SDT transformers. As a result of the PSA, the AOT for the SUT (a) is reduced from 7 days to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, while the AOT for the SDT (b) remains at 7 days. The reduction of the AOT from 7 days to 3 days is based on the relative risk importance of the SUT support to the balance of plant systems. Similarly an additional reduction from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is proposed in the AOT for a simultaneous loss of both the SUT or SDT and an EDG (TS 3.9.B.4) based upon the SUT's or SDT's contribution to risk and that two power sources have been removed from the associated bus. The AOT reductions represent a measurable decrease in risk as assessed in the PSA. Thus, the probability or consequences of an accident previously evaluated are not increased.

The current technical specifications allow one EDG to be out of service for three days based .

on the availability of the SUT and SDT and the fact that each EDG carries sufficient 1 engineered safeguards equipment to cover all design basis accidents. Additionally, the SDT  !

can provide adequate power for one train of ESF equipment for all operating, transient, and 1 accident conditions. With one EDG out of service and a Loss of Offsite Power (LOOP) I condition, the capability to power vital and auxiliary system components remains available via j the other EDG. Increasing the EDG AOT to 14 days provides flexibility in the maintenance  !

and repair of the EDGs. The EDG unavailability will be monitored and trended in accordance with the Maintenance Rule. The PSA analyses supports the change to a 14 day AOT for the EDGs based on an insignificant increase in overall risk. Implementation of the proposed i change is expected to result in less than a one percent increase in the baseline ccre damage frequency (2.84E-05/yr), which is considered to be insignificant relative to the underlying I uncertainties involved with PSA. An additional condition is added requiring the SBO-DG to remain operable for extending the inoperable EDG AOT from 3 days to 14 days, thereby assuring that one EDG and SBO-DG are available during the extended EDG AOT. Thus, the 14-day EDG AOT does not involve an increase in the probability or consequences of an accident previously evaluated.

The proposed addition of the CRMP does not involve a significant increase in the probability or consequences of an accident previously evaluated. Because the changes are administrative in nature and deal only with risk asbessment, they have no bearing on accident initiation or mitigation. Therefore, the changes will not affect the probability or consequences of an accident previously evaluated.

The proposed change does not affect the design or performance of the EDGs, and the change will not result in a significant increase in the consequences or probability of an accident previously analyzed. These changes do not involve a increase in the probability or consequences of an accident previously analyzed.

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2. The proposed amendment does not create the possibility of a new or different kind of accident from any accident oreviously evaluated.

The operation of PNPS in accordance with the proposed license amendment will not create the possibility of a new or different kind of accident from any accident previously evaluated because of the following:

The proposed amendment will extend the action completion / allowed outage time for an l inoperable EDG from 3 days to 14 days. During this extension, the SBO-DG is required to be operable and normal breaker configuration is required to be verified to ensure the SBO-DG is capable of energizing the safety bus associated with the inoperable EDG. These actions assure one EDG and SBO-DG are operable during extended EDG AOTs. The EDGs are designed as backup AC power sources for essential safety systems in the event of loss of offsite p;wer. The SBO-DG is designed to cope with a station black out transient. The proposed AOT does not change the conditions, operating configurations, or minimum amount of operating equipment assumed in the safety analysis for accident mitigation. The EDGs, SBO-DG and AC equipment are not accident initiators. No change is being made in the manner in which the EDGs provide plant protection. No new modes of plant operation are involved. An extended AOT for one EDG does not create a new or different kind of accident previously evaluated. The PSA results concluded the risk contribution of the EDG AOT 4 extension is insignificant.

Pilgrim has implemented an EDG reliability program to maintain reliability of EDGs. The SBO- .

DG is included in the reliabilhy program, and the performance of EDGs and SBO-DG are trended for compliance with Maintenance Rule requirements. Thus, the proposed change does not introduce any new mode of plant operation or new accident precursors, involve any i physical alterations to plant cefiguratens, or make changes to system set points that could '

initiate a new or different kind of accident. Therefore, operation in accordance with the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

The AOT for an inoperable SUT is reduced from 7 days to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> based upon the PSA that was performed to quantitatively assess the risk impact of the proposed amendment.

Additionally, removal of the SUT from service degrades the reliability of the offsite power system and renders the balance of plant unavailable upon a plant shutdown. The proposed reduction in AOT improves overall AC power source availability because the SUT will potentially be inoperable for shorter time periods. Therefore, reducing the AOT does not create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed addition of the CRMP does not create the possibility of a new or different kind of accident from any accident previously evaluated because the CRMP will not affect the manner in which SSCs are designed, operated, or maintained. The administrative changes proposed will only require a nsk assessment for specified plant configurations. Any risk assessments performed as a result of this program will only serve to provide plant personnel with risk insights associated with particular plant configurations. Since the changes will not impact SSCs and all accidents involving SSCs, the proposed change does not create a new kind of accident from any previously evaluated.

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3. The proposed amendment does not involve a significant reduction in a marain of safety.

The operation of PNPS in accordance with the proposed license amendment will not involve a significant reduction in a margin of safety. As shown in Part til (of the application dated April 25, 1996), incorporation of the proposed change. involves an insignificant reduction in the margin of safety (less than a one percent increase in the baseline core damage frequency

. (2.84E-05/yr), which is considered to be insignificant relative to the underlying uncertainties involved with PSA).

Also, the proposed changes do not significantly reduce the basis for any. technical specification related to the establishment of, or the maintenance of, a safety margin no.- do

- they require physical modifications to the plant. 'An additional condition is added requiring the SBO-DG to remain opernble, in addition to the operable EDG associated with the redundant train while in the 14 day EDG AOT. The PSA results showed that the risk contribution of extending the AOT for an inoperable EDG is insignificant. Also, the reduction in the AOT for the SUT should improve availability ~thereby reducing overall risk with no reduction of the safety margin. Moroover, the proposed changes affect neither the way in which the EDGs perform their safety function nor the bases for their LCOs.

The proposed change does not involve a significant reduction in a margin of safety. The proposed administrative change to include a risk management program will not impact how plant SSCs are ~ designed, operated, or maintained. The required risk assessments are

!ntended to provide insights that influence decisions on the acceptability of abnormal plant configurations. These insights work in conjunction with existing inputs into the decision-making process rather than as the sole basis for making decisions. 'Therefore, the changes

. will not reduce a margin of safety.

As'previously stated, implementation of the proposed changes is expected to result in an insignificant increase in: (1) power unavailability to the emergency buses (given that a loss of offsite power has occurred), and (2) core damage frequency. Implementation of the proposed changes does not significantly reduce a margin of safety.

Conclusion:

The above analysis of no significant hazard consideration determination satisfies the three standards of 10 CF 50.92(c). The above proposed changes have been prepared to utilize the diversity of AC power and preserve the validity of the safety analysis while providing sufficient flexibility in the limiting condition of. operability to accommodate -the need' for maintenance and surveillance of equipment. These proposed changes have been reviewed and approved by the Operations Review Committee and reviewed by the Nuclear Safety Review and Audit Committee at PNPS,

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