ML20238F298
| ML20238F298 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/27/1998 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20238F299 | List: |
| References | |
| TVA-SQN-TS-96, TVA-SQN-TS-96-0, NUDOCS 9809030256 | |
| Download: ML20238F298 (16) | |
Text
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IM Tennessee Valley Authority, Post Office Box 2000, Soddy-Daisy, Tennessee 37379-2000 August 27, 1998 TVA-SQN-TS-96-08, Revision 1 10 CFR 50.90 U.S._ Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen.
In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - UNITS 1 AND 2 - TECHNICAL SPECIFICATION (TS) CHANGE NO. 96-08, REVISION 1, SECTION 3.8.1, "A.C. SOURCES" AND RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION
References:
- 1. TVA letter to NRC dated August 22, 1996, Sequoyah Nuclear Plant (SON) - Technical Specification (TS) Change 96-08, Section j 3.8.1, "A.C. Sources" j l
- 2. NRC letter to TVA dated July 14, 1997, i
" Issuance of Technical Specification Amendments for the Sequoyah Nuclear Plant, / l Units 1 and 2 (TAC Nos. M96600 and M96601) (TS f 96-08)"
- 3. NRC letter to TVA dated November 26, 1997,
" Request for Additional Information-Technical Specification Change Request TS 96-08 for O Sequoyah Nuclear Plant, Units 1 and 2 (TAC I . m. * ? Nos. M96600 and M96601)"
U.S. Nuclear Regulatory Commission Page 2 August 27, 1998 In accordance with the provisions of 10 CFR 50.4 and 50.90, TVA is submitting a revised request for an amendment to SON's licenses DPR-77 and 79 to change the TSs for Units 1 and 2.
The proposed change revises the original request submitted by Reference 1. This revision replaces the original request for a once every 18-month provision for a 7-day emergency diesel generator (EDG) allowed outage time (AOT) with a permanent 7-day AOT for one or more inoperable EDGs in a single train.
Appropriate revisions to TS Section 3.8.1.1 have been included along with necessary changes to the bases. This revised request does not alter the portions of the original request that was approved by NRC in Reference 2 and has been implemented by TVA. Additional changes have been proposed to delete reporting requirements associated with the change approved by Reference 2. An obsolete License Condition that no longer applies regarding implementation of EDG design and procedure modifications is also proposed for deletion.
TVA has determined that there are no significant hazards considerations associated with the proposed change and that the change is exempt from environmental review pursuant to the provisions of 10 CFR 51.22 (c) (9) . The SON Plant Operations Review Committee and the SQN Nuclear Safety Review Board have reviewed this proposed change and determined that operation of SQN Units 1 and 2 in accordance with the proposed change will not endanger the health and safety of the public. Additionally, in accordance with 10 CFR
- 50. 91 (b) (1) , TVA is sending a copy of this letter to the Tennessee State Department of Public Health.
Enclosure 1 to this letter provides the description and evaluation of the proposed change. This includes TVA's determination that the proposed change does not involve a significant hazards consideration, and is exempt from environmental review. Enclosure 2 contains copies of the appropriate TS pages from Units 1 and 2 marked-up to show the proposed change. Enclosure 3 forwards the revised TS pages for Units 1 and 2 which incorporate the proposed change.
Enclosure 4 contains the response to the NRC Request for Additional Information in Reference 3.
U'S. Nuclear Regulatory Commission Page 3
' August 27,'1998 These change' scare ~needed to support required EDG maintenance, which'is scheduled to start.in' January 1999.. NRC approval of
- the proposed TS change.is requested'by October 19,.1998, to support this required maintenance. TVA requests that the revised.TS be made effective within 45 days of NRC approval.
- If you have any questions about this change, please telephone me at . (423) 843-7170 or J. D.' Smith at (423) 843-6672.
Sincerely, ,
t Pedro,$ alas
/
Licensing and Industry Affairs Manager
'bscribed.3nd sworn fore m
' on this c27re ' day of. to-l$1 lAJ Notaff Public /
My Commission Expires ' October 21, 1998 Enclosures-cc: See page 3 s'
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c - . _____ _ . - _ _
U.S. Nuclear Regulatory Commission j'
Page 4 August 27, 1998 cc (Enclosures):
Mr. R. W. .Hernan, Project Manager Nuclear Regulatory Commission One-White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 Mr. Michael H. Mobley, Director (w/o Enclosures)
Division of Radiological Health Third Floor L&C Annex 401 Church Street Nashville, Tennessee 37243-1532 NRC Resident Sequoyah. Nuclear. Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303-3415
ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 and 2 DOCKET NOS 327 AND 328 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE TS-96-08, REVISION 1 DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGE I. DESCRIPTION OF THE' PROPOSED CHANGE TVA has revised the original request dated August 22, 1996. This revised change replaces the 72-hour <
allowed outage time (AOT) of TS 3.8.1.1, Action b, with a 7-day AOT requirement for the inoperability of one emergency diesel generator (EDG) or one train of EDGs.
The proposed change will also delete the current footnote that provides a 72-hour extension of this action for cleaning activities of the fuel oil storage tank. This note will not be necessary after implementation of the 7-day AOT. The associated bases have been revised as appropriate.
Other changes are proposed in this request to fully implement the deletion of accelerated testing of the EDGs as approved by NRC on July 14, 1997. This includes the deletion of reporting requirements associated with EDG reliability and the annual EDG reliability report in TS Sections 4.8.1.1.4, 4.8.1.2, and 6.9.2.2. The proposed change also deletes License Condition, 2.C.(15) for Unit 1 and 2.C.(12) for Unit 2, associated with the implementation of EDG design and procedure modifications, that are no longer applicable.
II. REASON FOR THE PROPOSED CHANGE q TVA originally requested an extension to the EDG AOT in the i August 22, 1996, letter on a once every 18-month basis.
This was in consideration of the SON schedule for the major 12- and 6-year maintenance activities that are required to 1 be performed in early 1999. The scope of this maintenance j is substantially larger and a 7-day AOT will reduce entries i into limiting conditions for operation (LCO) action i statements, reduce EDG unavailability, decrease the number )
of required EDG starts, and reduce the risk associated with activities necessary to complete this effort.
TVA has reevaluated the original TS change request for a once every 18-month AOT extension. Based on the potential El-1
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l l for other maintenance and testing activities that could benefit from an extended AOT and the past history of the EDGs being the primary cause for enforcement discretion, an AOT extension that can be applied any time was~ determined to be more desirable. NRC also indicated in their l November 26, 1997, Request for Additional Information (RAI), that the current staff position is-not to make such changes on a "once per" bases and requested that TVA l resubmit as a one-time or permanent change request. The l 12- and 6-year maintenance that is primarily driving this change request, will occur again during the life of the plant, as well as other potential maintenance activities-that could benefit from the extension. Therefore, it is in TVA's best interest that a permanent AOT extension for the
, EDGs be approved instead of the once every fuel cycle or one-time extension.
l The proposed deletion of the footnote to Action b of TS 3.8.1.1 is requested because the current provision to extend the 72-hour action for an additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is not necessary if the proposed change is implemented. The proposed 7-day action provides adequate time for the <
cleaning of the fuel oil storage tank. Additional time, I beyond the 7-day AOT for this cleaning activity, is not I appropriate from a duration of work standpoint. )
i The deletion of the EDG failure and reliability reporting requirements is proposed because these provisions are not r.ecessary based on the implementation of the Maintenance Rule, in accordance with 10 CFR 50.65. This rule controls I the EDGs such that acceptable EDG reliability is maintained or appropriate corrective actions are taken.
Specific reports to the NRC are not necessary considering the controls placed on the EDGs through the Maintenance Rule requirements. The NRC approved changes in the July 14, 1997, letter removed the accelerated testing j requirements from the TSs based on the implementation of '
the Maintenance Rule. The deletion of the reporting requirements should have been included in TVA's original TS change request, but was overlooked at that time. j The proposed change also deletes License Condition, 2.C.(15) for Unit 1 and 2.C.(12) for Unit 2, associated with the implementation of EDG design and procedere modifications that are no longer applicable. This License Condition was satisfied prior to operation following the first refueling outage of each unit and has no remaining actions applicable to SON. This deletion will remove an obsolete and unnecessary license condition.
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l- III. SAFETY ANALYSIS l
The electrical system design is described in Section 8.0,
, " Electrical ~ Power," in the SQN Final Safety Analysis L ; Report (FSAR). SQN is. connected to a strong offsite transmission network. The transmission lines'are on right I of ways which are sufficiently wide enough-to preclude the likelihood of a failure of one line causing failure of the other line. These lines are diverse.in the fact that they leave the site area:in many directions-to a large number of diverse generating units. Over the past 5 years, 8 161-kV transmission lines to Sequoyah have been L . simultaneously available for more than 99 percent of the time with 4aof these'8 lines available simultaneously _for 100 percent of the time.
p ' Electric power to SON is supplied by two physically and electrically independent circuits from the Sequoyah 161-kV switchyard through three separate transformers to the onsite electrical distribution system. Two transformers-are normally in operation with the third available as a l spare.that_can be automatically transferred in the event of a transformer failure. The 161-kV switchyard is designed with'two main bus sections and is arranged so that the supply to the onsite power system, as well as the connections-to the_ generator and the 500-161-kV intertie transformer bank, is maintained to one bus section for a failure of the'other section. Four 161-kV lines terminate on one bus and four other 161-kV lines terminate on the other bus. Two fuseless 84 MVAR 161-kV capacitor banks are-tied to the 161-kV swltchyard through double bus-tie breakers. Each bank is independently switched. These capacitors provide reactive voltage support'for the 161-kV offsite system.
--SON has two nearby hydro power sources connected via three 161-kV transmission lines. Following a major grid disturbance or collapse these, facilities are required by prewritten "blackstart" procedures to reenergize their switchyards from one-of their hydro units, which can be
-placed in service with local emergency generators, and
. energize one or more of the transmission lines to SON.
Restoration time is estimated'to be 30 minutes. One of these hydro facilities is located to the south while the other is' located to the north of SQN. This arrangement
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- i. , provides. additional diversity and redundancy to ensure that SQN can be supplied with offsite power even in the event of a major grid disturbance or environmental conditions that result in significant transmission system
! damage. This source of offsite power is not a qualified source, in accordance with the TS requirements, but is a l
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source of power that can enhance the site's ability to restore the units to normal conditions.
Several. improvements to the plant / grid interfaces at SON have been made since the 72-hour AOT was established.
They include:
- 1. Replacing the common station service transformers (CSSTs) with ones having automatic high-speed onload voltage tap changers in order to maintain optimal voltages to the safety-related system while connected to the preferred. power supply (PPS) and during all modes of plant startup, shutdown, and operation. With the installation of these new transformers, the in-plant auxiliary power system can accommodate a transmission system bandwidth of +/-5% of nominal versus the previous 1-2% bandwidth capability.
- 2. SON has implemented a design change which provides for the in-plant alternating current auxiliary power system to be-normally fed from the PPS during all modes of plant operation, startup, and shutdown. This increases reliability by reducing plant transfers during a plant shutdown and provides better voltage regulation to the safety-related boards during all modes of plant operation.
- 3. SQN installed two 84 MVAR capacitor banks outside the 161-KV switchyard to provide reactive power support to the plant during a Unit 2 trip and shutdown.
- 4. Transmission Power Systems performs comprehensive transmission system studies for TVA nuclear plants on a three-year cycle. These studies include load flow analyses and transient stability studies and are performed in accordance with the guidelines in IEEE-765-1995 for transmission system studies. This verification ensures that SON can withstand a loss-of-coolant accident in one unit and orderly safe shutdown of the other unit and a simultaneous transmission contingency.
Preferred power to SON is supplied by either of the 161-kV l buses to three CSSTs. The CSSTs supply power to the four start buses (SBs), and the four SBs supply power to the i eight unit boards. There are four unit boards per unit L
and the unit boards supply power to the four shutdown boards with two shutdown boards'per unit. Each of the shutdown boards supply a single train of safe shutdown equipment along with some common equipment. The shutdown boards can also be supplied emergency power by seismic and environmentally qualified EDGs that supply backup power to El-4 o..._________________
the vital 6.9-kV, and 480-V busses in the event of a loss )
of offsite power.
l During power operation, the EDGs help to ensure that
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sufficient power will be available to the safety-related
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, equipment, which is needed for safe shutdown of the plant and for mitigation and control during accident conditions.
During shutdown and refueling conditions, the EDGs help to j
ensure that the facility is able to maintain shutdown or '
refueling conditions for extended periods of time.
SON EDGs have high availability and reliability ratings.
For implementation of the Station Blackout Rule, 10 CFR 50.63, SON established a EDG target reliability of 0.975.
As of March 1992, the SON EDGs each had an average I
reliability of 0.999 and SQN has continued to demonstrate high EDG performance. SON EDG unavailability over a 24-month interval for 1994 was 0.017; for 1995, 0.015; for i
1996, 0.010; for 1997, 0.012; and for 1998, the year-to-date value is 0.011. These values are well below the year 2000 industry goal of 0.025 for each EDG. I SON's EDG configuration is such that four of four EDGs are required to be operable to operate one unit (except under LCO action statement conditions). This is based on the i common equipment that is supplied by each EDG and is required to support each SON unit. Since it is not practical to schedule outages of both units simultaneously, EDG maintenance must be performed at power under LCO conditions for at least one unit.
SON routinely carries out planned maintenance on the EDGs during power operation. Planned surveillance for the !
EDGs are conducted on schedules that include weekly, I monthly, quarterly, once per refuel cycle, every 24 I months, every 36 months, every 72 months, every 10 years, i and every 12 years. The activities are as simple as l checking the oil level to as complicated as engine rebuilding. Many activities performed on the 18 month and longer schedules require the EDG to be removed from service. Experience has shown that, even with careful planning, maintenance duration sometimes approaches the current 72-hour AOT. In order to accommodate unanticipated problems, SON has developed the practice of scheduling. work for only 50 to 60 percent of the AOT. It is estimated that the proposed 7-day AOT would reduce EDG unavailability by approximately 50 percent for the upcoming'12- and 6-year maintenance that is scheduled for January 1999. Maintenance a'ctivities that are currently being performed within the 72-hour AOT provision are not expected to change. However, future considerations may indicate improvements in EDG availability by combining El-5 w__
activities into fewer outages of the EDGs, which would i
result in additional risk reductions.
The maximum expected EDG unavailability under the current maintenance schedule with the 72-hour AOT is 434 hours0.00502 days <br />0.121 hours <br />7.175926e-4 weeks <br />1.65137e-4 months <br /> per EDG per year. This will result in a core damage frequency
-(CDF) of 4.19E-5. With the 7-day AOT, the EDG maximum expected unavailability is 332 hours0.00384 days <br />0.0922 hours <br />5.489418e-4 weeks <br />1.26326e-4 months <br /> per EDG per year, with a CDF of 4.13E-5. This reduction is the result of being able to perform the required maintenance in a single AOT entry as. opposed to five entries. This significantly l decreases the amount of clearance activities and testing required and accounts for the majority of the reduction.
Additional reductions result from the ability to work more activities in parallel with the~ longer AOT.
The risk associated with shutdown operations will not change due to this requested change. At SON, the shutdown i risk philosophy is based on a defense in depth approach. l This approach requires TS plus one availability without plant management approval. Outage scheduling flexibility will improve if the EDGs are not required to be out of ,
service during an outage. Other surveillance testing and l maintenance will be easier to schedule with improved EDG l availability during outages. Refueling outage activities will be more efficient and shutdown risk will be reduced.
The evaluation of the risk associated with the proposed extension of the EDG AOT from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days has been performed in accordance with the draft guidance in NRC's Draft Regulatory Guide DG-1065, dated June 1997. TVA has used a three tier approach to ensure the risk informed aspects of'this AOT extension is properly considered.
Tier 1 assesses the impact of the TS change and demonstrates the validity of the probabilistic risk assessment (PRA). Evaluations of the core damage frequency (CDF) and other risk considerations associated with the proposed change have been based on Revision 1 of the SON Individual Plant Evaluation (IPE). Tier 2 provides reasonable assurance that risk-significant plant configurations will not occur as a result of AOT extensions. Tier 3 considers the programs that ensure risk impacts are properly evaluated prior to performing maintenance activities.
TVA's approach to Tier 1 of the draft regulatory guide l utilized evaluations of the change in CDF, the incremental conditional core damage probability (ICCDP), and the incremental conditional large early release probability (ICLERP). The evaluation of these factors resulted in a reduction in risk when comparing the use of the 7-day AOT instead of the 72-hour AOT during the years when the 12-El-6
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and 6-year maintenance is performed. For other years, risk is not affected based on maintenance activities being scheduled in the same manner. The increase in CDF related to the Maintenance Rule unavailability limit case for the 12- and 6-year maintenance is 1.8% and 3.1% for the proposed 7-day AOT and current 72-hour AOT, respectively.
~These increases are not risk-significant and are further minimized by the fact that EDG unavailabilities are expected to be much less during the nonmaintenance years.
The CDF for the largest EDG unavailability considered for the proposed 7-day AOT (i.e., EDG unavailability equal to the Maintenance Rule unavailability limit of 219 hours0.00253 days <br />0.0608 hours <br />3.621032e-4 weeks <br />8.33295e-5 months <br /> plus 1, 7-day AOT for a total unavailability of 387 hours0.00448 days <br />0.108 hours <br />6.398809e-4 weeks <br />1.472535e-4 months <br />) is 4.16E-5/ year which is a nonrisk-significant 2.5% increase over the base CDF of 4.06E-5/ year. The ICCDP considering a single 72-hour and 7-day AOT is 2.14E-7 and 4.98E-7, respectively. The ICLERP considering a single 72-hour and 7-day AOT is 9.03E-9 and 2.10E-8, respectively. The 1 increase in ICCDP and ICLERP for the 7-day AOT are not risk-significant. Further explanation of these results can be found in the answers to Questions 5, 5(b), 13.
TVA submitted Revision 1 of the SQN IPE to NRC on '
February 20, 1998. This evaluation was performed by an integrated team of engineers and PRA specialists from TVA and ERIN Engineering and Research, Inc. This effort involved a comprehensive review of the Level 1 PRA and updated portions of the PRA as appropriate. The validity of. the Revision 1 IFE is demonstrated further by the responses to several of the RAI questions in Enclosure'4 of this submittal that reflect the conservative approach in developing this revision. Specifically, responses to l questions regarding cutset truncation cutoff, treatment of common cause failures, impact of severe weather, initiating event frequency, and the definition of large early release frequency, demonstrate this conservative approach. These efforts support the accuracy and validity of the SON IPE Revision 1 and the expectations for Tier 1.
TVA has evaluated risk significant events for the proposed EDG AOT extension as part of the Tier 2 effort. In the response to Question 5(e) of the enclosed RAI response, the Risk Achievement Worth of top events and systems was evaluated. The results indicated that there was i essentially no change in risk for the top events and I systems. There was a slight shift in some rankings and the addition of one event is added where it was slightly below the' threshold for inclusion previously. The RAI responses to Questions 5(f), 11, and 12 describe plant processes and i procedures that are utilized to maintain nonrisk- l significant configurations. These attributes support the intent of the Tier 2 approach to ensure that risk El-7
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significant plant configurations are not created or are properly addressed for the proposed AOT extension. TVA's current on-line risk assessment process at SQN is sufficient to properly assess the risk associated with plant activities. Since the TVA evaluation determined that no significant change in risk was involved'for this request, TVA is not proposing any changes to the current processes, plant design or TS requirements for other systems or functions.
The Tier 3 approach for the proposed AOT extension is supported by many of the same discussions in the RAI i responses referenced for Tier 2. The responses for Questions 5 (f), 11, and 12 include SON's method for evaluating maintenance activities prior to work to ensure risk significant configurations are not created. These controls contain several levels of risk evaluations and methods to react-to changing plant conditions and emergent work activities. These processes provide a conservative approach to maintaining nonrisk-significant plant l configurations. TVA is not proposing the addition of a l configuration risk management program into the SON TSs. "
This is based primarily on the position documented in NRC's SECY-98-165 that indicates that future changes to i Maintenance Rule, 10 CFR 50.65, will incorporate 1 requirements that will serve the same purpose. TVA plans to continue to utilize the processes described to control risk configurations at SON and will continue these efforts .)
after the final rule change is implemented. This decision will eliminate the need to remove TS requirements in the future that will not be necessary after the Maintenance Rule change. TVA believes this approach satisfies the intent of Tier 3 considering the upcoming changes to 10 CFR 50.65.
The three tier approach, utilized by TVA, supports the acceptability of the proposed extension of the EDG AOT from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days. The reductions in EDG unavailability and plant risk for the upcoming 12- and 6-year maintenance ,
activities further supports the value of implementing this :
-change. Implementation of the proposed AOT extension to 7 days for the EDGs will not result in adverse impacts to I nuclear safety.
The deletion of the footnote in TS 3.8.1.1, Action b, regarding the additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for fuel tank cleaning, removes a provision that no longer is necessary or appropriate. The proposed 7-day AOT for the EDGs provides an out-of-service duration in excess of the additional 72-hour provision in the current footnote. TVA has demonstrated that 6 days is sufficient time to perform this maintenance based on past performances and it would not be El-8
appropriate to maintain the 72-hour AOT extension in addition to the proposed 7-day AOT. This deletion of the current EDG AOT extension is conservative and will not adversely impact nuclear safety by maintaining EDG out-of-service times within acceptable limits.
The deletion of reporting requirements associated with EDG reliability and' failures is an administrative change to accommodate changes already approved by NRC. The TS
- j. requirements for accelerated testing of EDGs, based on the L number.of failures, was approved for deletion on July 14, 1997, by NRC. This change was deemed acceptable based on the implementation of the Maintenance Rule at SON.
.The Maintenance Rule provisions monitor EDG unavailability and failures'and prescribes actions to be~ taken in the event of adverse failure trends or excessive out-of-service times. These same Maintenance Rule provisions eliminate
,the need for the reporting requirements in the TSs associated with the EDGs because NRC notification and monitoring of EDG reliability has been adequately incorporated into the Maintenance Rule programs at SQN.
Therefore, the deletion of the TS reporting requirements for the EDGs will not result in adverse impacts to nuclear safety. These changes are also consistent with Standard TS (NUREG-1431).
The deletion of the obsolete License Condition regarding the implementation of EDG design and procedure modifications is administrative in nature. This condition involved actions to be completed prior to unit operation following the first refueling outage on each unit. TVA performed the necessary design and procedure activities to support completion of this condition in the early 1980s.
This License Condition provides no further benefit and currently has no associated open actions. Therefore, this )
deletion will remove unnecessary.information and will not l adversely impact nuclear safety. l IV. NO SIGNIFICANT HAEARDS CONSIDERATION DETERMINATION l .TVA'has concluded that operation of SON Units 1 and 2, in accordance with the proposed change to the TSs and operating licenses, does not involve a significant hazards consideration. TVA's conclusion is based on its evaluation, in accordance with 10 CFR 50. 91(a) (1) , of the three standards set forth in 10 CFR 50.92(c).
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l A. The proposed amendment does not involve a significant l increase in the probability or consequences of an accident previously evaluated.
I The EDGs supply backup power to the essential safety systems in the event of a loss-of-offsite (normal)
. power. The EDGs are not postulated to be an initiator l of a design basis accident. The requested change to
- provide a 7-day AOT for the EDGs and the deletion of L the additional 72-hour extension for this AOT will not L impact the plant design, components or operational practices. The increased out-of-service time does not invalidate assumptions used in evaluating the l radiological consequences of an accident and does not j
provide a new or altered release path. In addition, ,
the administrative changes to delete EDG reporting l requirements and an obsolete License Condition will not impact plant equipment or operating practices.
Therefore, this change does not involve an increase in the probability of any accident previously evaluated.
An increase in the AOT for the EDGs would not change
- the conditions, operating configuration or minimum amount of operable equipment assumed in the plant Final Safety Analysis Report for accident mitigation. The l longer AOT would provide a longer time window for l maintenance, but would lesson the overall EDG unavailability, therefore, it would reduce plant risk.
The CDF associated with a 7-day AOT increases from the base case in the SON IPE but is not risk-significant.
This CDF increase is based on sensitivity studies performed in accordance with the guidance in Draft Regulatory Guide DG-1065, dated June 1997. These studies assume additional unavailability of the EDGs for an increase in AOT even though plant practices are not expected to change. The EDG availability L improvements and CDF reductions during 12- and 6-year maintenance activities compensates for this potential increase to provide an overall safety benefit.
The deletion of the footnote for extending the AOT for fuel tank cleaning removes inappropriate extensions of EDG out-of-service time. SON's implementation of the Maintenance Rule, 10 CFR 50.65, also supports the ,
proper scheduling and performance ~of maintenance !
activities to ensure EDG unavailability is adequately I controlled. Based on no change in plant risk during !
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, routine. maintenance, because work activity durations are unchanged, and the decrease in overall plant risk during the 12- and 6-year maintenance activities, as a result of.the'7-day EDG action time, this change will not result in a significant increase in the consequences of an accident. In addition, the administrative deletions of reporting requirements that are not necessary based on Maintenance Rule implementation and obsolete License Condition deletion will not increase the consequences of an accident.
B. The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.
The proposed change to extend the AOT for the EDGs and delete unnecessary TS and operating license provisions does not alter the physical design or configuration of the plant. The EDG operation remains unchanged, therefore, this change does not create the possibility of a new or different kind of accident from any previously analyzed.
C. The proposed amendment does not involve a significant-reduction in a margin of safety.
The proposed extension of the EDG action time for inoperable units to 7 days will not alter plant equipment, setpoints or operating practices that provide the necessary margin of safety. The extension will reduce EDG unavailability and plant risk such that the EDG's ability to react to accident situations is increased. Overall CDF, as a result of a 7-day AOT, indicates a slight increase but it is not significant.
The ACT extension deletion for fuel tank cleaning is a conservative change to maintain appropriate EDG out-of-service times. The deletions of administrative requirements for reporting EDG reliability and obsolete License Conditions do not impact functions that j maintain the margins of safety and have been or are {
continuing to be satisfied by other regulatory j requirements. Therefore, the proposed change does not involve a significant reduction in the margin of safety.
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I V. ENVIRO!ORENTAL IMPACT CONSIDERATION
.The proposed change does not involve a significant hazards. consideration, a significant change in the types of or significant increase in the' amounts of any effluents that may beEreleased offsite, or a significant' increase in individual or cumulative -
occupational radiation _ exposure. Therefore, the proposed change meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22 (c) (9) . j Therefore, -pursuant to 10 .CFR 51.22 (b) , an '
environmental assessment of the proposed change is not required.
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