ML20209B766

Application for Amends to Licenses DPR-77 & DPR-79,updating Current TS Requirements for RCS Leakage Detection & RCS Operational Leakage Specifications to Be Consistent with NUREG-1431

ML20209B766
Person / Time
Site:	Sequoyah
Issue date:	06/30/1999
From:	Salas P TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20209B772	List: ML20209B766 ML20209B773
References
RTR-NUREG-1431 TVA-SQN-TS-98-1, NUDOCS 9907080109
Download: ML20209B766 (20)

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Tennessee Valley Authonty Post Office Box 2000. Soddy-Daisy Tennessee 3/379 June 30, 1999 i

TVA-SQN-TS-98-10 10 CFR 50.90 (

l 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. 98-10, " ENHANCEMENT OF REACTOR COOLANT LEAKAGE DETECTION AND OPERATIONAL LEAKAGE CONSISTENT )

WITH STANDARD TECHNICAL SPECIFICATIONS" (NUREG-1431)

In accordance with the provisions of 10 CFR 50.4 and 50.90, TVA is submitting c request for an amendment to SON's licenses DPR-77 and 79 to change the TSs for Units 1 and 2.

The proposed change will update the current TS requirements for reactor coolant system (RCS) leakage detection and RCS operational leakage specifications consistent with the 3 I

recommended content of NUREG-1431. In order to accomplish l ,

this enhancement, the generation of two new specifications is f !

required to maintain consistency with NUREG-1431. The new specifications address the requirements for RCS pressure isolation valves and seal injection flow. The requirements in these new specifications are currently contained in the RCS operational leakage requirements. TVA also proposes the j addition of expanded Bases sections, consistent with j)g],C)

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NUREG-1431, to' support these revisions and the necessary revisions to the TS index and definitions. .

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9907090109 990630 17 i PDR ADOCK 050003272  ;

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U.S. Nuclear Regulatory Commission

-Page 2 June 30, 1999:

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

~ l the provisions of 10 CFR 51.22 (c) (9) . The SON Plant ,

Operations Review Committee and the SQN Nuclear Safety Review I Board have reviewed this proposed change and determined that l' operation of SON Units 1 and 2, in accordance with the proposed change, will not endanger the health and safety of the public. Additionally, in accordance with 1 10 CFR. 50.91(b) (1), .TVA is sending a copy of this letter to the Tennessee State Department of Public Health.

1 Enclosure 1 to this letter provides the' description and J

evaluation of the proposed change. This includes TVA's j determination that'the proposed-change does not involve a l

-significant hazards consideration and is exempt from l environmental review. Enclosure 2 contains copies of the appropriate TS pages from Units 1 and 2 marked up to show the proposed change. Encl'osure 3 forwards the revised TS pages 4 for Units 1 and 2,which incorporate the proposed change.

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.

Si er-el y ,

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Ped a as 1 censing'and Industry Affairs Manager L

Subscribed and. sworn t Joefore me

. on; this Sn* day of d o u es I

L0 F6 Notary'Public W-

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My Commission Expires October 9, 2002 Enclosures cc: See Page 3 i

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r-U.S. Nuclear Regulatory Commission Page 3 June 30, 1999 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 l 2600 Igou Ferry Road

Soday-Daisy, Tennessee 37379-3624 l

l Regional Administrator l U.S. Nuclear Regulatory Commission l Region II

! Atlanta Federal Center l 61 Forsyth St., SW, Suite 23T85 l

Atlanta, Georgia 30303-3415 i

i i

ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (SQN)

UNITS 1 AND 2 DOCKET NOS. 327 AND 328 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE 98-10 DESCRIPTION AND EVALU.ATION OF THE PROPOSED CHANGE i

I. DESCRIPTION OF THE PROPOSED CHANGE TVA proposes a revision to several portions of the SON TSs in order to develop specifications associated with reactor coolant system (RCS) leakage that are consistent with the I latest version of the standard TSs (NUREG-1431) and NRC I approved revisions to these TSs (i . e . , TSTF-54, Revision 1; TSTF-60, Revision 0; and TSTF-116, Revision 2.) The revisions to TS Section 3.4.6.1, "RCS Leakage Detection  ;

System," include the renaming of the section to Leakage l Detection Instrumentation. The limiting condition for operation (LCO) has been revised to mirror NUREG-1431 by specifying the minimum required leakage detection features and refers to them as monitors rather than systems. The action requirements for this specifica has been modeled after NUREG-1431, such that individual , tons necessary for inoperable monitors have been provided for each type of inoperable detection monitor and an action for no detection monitors operable. The action times have been developed in accordance with the intervals in NUREG-1431, and a footnote has been incorporated to clarify the conditions for performing RCS inventory balance activities. The surveillances have not been altered in intent, but have been revised to utilize the concept of monitors versus monitoring systems and for consistency with NUREG-1431 wording.

TS Section 3.4.6.2, "RCS Operational Leakage," has also l been revised to be consistent with NUREG-1431. This -

revision relocates the requirements for controlled leakage I (seal injection flow) and pressure isolation valve leakage j to two new specifications (3. 4. 6. 3 and 3. 5. 6) . In <

conjunction with this change, the definitions in l Section 1.0 of the TSs have been revised accordingly. This  !

involves the deletion of the definition for controlled leakage and modification of identified leakage and unidentified leakage definitions to address controlled leakage as seal injection flow. Other minor editorial enhancements, as provided in NUREG-1431, have been  !

incorporated. The NUREG-1431 provision for total primary l El-1

to secondary leakage through all steam generators (S/Gs) was not included because of recent NRC approved SON License I Amendments 222 and 213 for Units 1 and 2, respectively, that have justified this omission, dated April 9, 1997.

Section 3.4.6.2 actions have been revised to accommodate the removal of the pressure isolation valves from this specification. Otherwise, the actions are unchanged and are consistent with NUREG-1431. Several of the current surveillance requirements (SRs) have been deleted because of the controlled leakage and pressure isolation valve relocation or in accordance with recommended requirements in NUREG-1431. The deleted surveillances for the NUREG include those that are associated with leak detection and the reactor head flange leakoff surveillance. A surveillance has been added to address the S/G tube integrity verifications, and a footnote has been incorporated to describe the appropriate time to perform the RCS inventory balance such that accurate results will be accomplished. In order to complete the relocation of the pressure isolation valve requirements, Table 3.4-1 that lists these valves has been moved to the new Specification 3.4.6.3.

New Specification 3.4.6.3 is being added to provide the requirements for the RCS pressure isolation valves. The operability requirements along with the applicability, actions, and SRs have been developed consistent with NOREG-1431. Those portions of NUREG-1431 that are not l applicable to the SQN design or that provide a relaxation l or exclusion that is not appropriate have not been included in the proposed request.

The LCO requirements have been modified to utilize the current industry criteria for leakage limits of less than or equal to 0.5 gallons per minute (gpm) per nominal inch of valve size up to a maximum of 5 gpm. The applicability l requirements have been revised to provide an exception to the residual heat removal (RHR) system flow path in Mode 4 when in or during transition to or from RHR operation. The actions have been modified to allow a limited time of operation with valve leakage above this limit provided the flow path is isolated. This isolation must be with a valve that has been tested and meets the same leakage requirements of this specification, as well as being within the reactor coolant boundary. Additional action requirements have been included for clarity involving the ability to separately enter this action for each inoperable flow path and the need to enter applicable actions for systems rendered inoperable by the inoperable RCS pressure isolation valve. The surveillance testing requirements are not changed by this request; however, the current criteria that specifically requires the performance of the 1

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T curveillance following maintenance, repair or replacement  !

work on the valve, has been removed; and the duration in cold shutdown before requiring performance has been extended to 7 days. The changes to SON's current requirements described above are consistent with NUREG-1431. TVA has included a listing of pressure isolation valves associated with this specification that contains the same information found in the current operational leakage specification.

l New Specification 3.5.6 is being added to provide the

! requirements for the seal injection flow. This I

specification takes the place of the current requirements in the operational leakage specification for controlled leakage. The new specification is fashioned after NUREG-1431; however, a modification to the NUREG has been incorporated that utilizes a relationship involving the pressure differential between the charging pump discharge header and the RCS and total seal injection flow. This method for determining acceptable seal injection flows does not require the current provision to have the modulating valve fully open in consideration of the SON design for the i location of the header pressure sensor. The current flow I limit of 40 gpm at normal RCS pressure is replaced by range I of flow limits that correspond to this amount of flow restriction over various amounts of pressure differential between the header and the RCS.

The surveillance for Specification 3.5.6 will utilize this range of differential pressures and associated flow values to verify acceptable settings of the seal injection throttle valves. The figure that contains these relationships will be provided in the associated Bases for this specification. A footnote, consistent with NUREG-1431, has been added to the surveillance that clarifies the need to be at normal RCS pressure and stabilized for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to the performance of the flow verification. This provision replaces the existing exception for Specification 4.0.4. This specification will apply in Modes 1, 2, and 3, which is a modification of the current requirement that includes Mode 4. As a result of this change, the action will only require a shutdown to Mode 4 within a total of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if inoperable seal injection flows cannot be corrected.

TVA is adding expanded Bases for each specification revised in this proposed change. These Bases have been developed in accordance with the recommendations of NUREG-1431.

Modifications and omissions have been utilized where necessary to agree with the specific requirements proposed and the SQN design. The proposed Bases for Specifications 3.4.6.1 and 3.4.6.2 supersede the current El-3

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c L discussions. TVA has also proposed the necessary revisions to the TS index'to support the specification and Bases changes described above.

II. REASON FOR THE PROPOSED CHANGE

, The purpose of the proposed change to the SON TSs is to i provide requirements that are more consistent with the industry standard in accordance with NUREG-1431. TVA is utilizing this revision to relocate requirements to new  :

specifications that provide better implementation and are l fasitioned to address the appropriate safety systems. These i relocations are consistent with NUREG-1431 and subsequent i NRC approved changes (i.e., TSTF-54, Revision 1; TSTF-60, I Revision 0; and TSTF-116, Revision 2). TVA is deleting items, in accordance with NUREG-1431, that are not necessary for maintaining operability of these systems or are adequately covered by requirements in other j specifications. These revisions also incorporate modifications for the LCOs, applicability, action times, and SRs.that are acceptable based on the SQN design and NUREG-1431 recommendations. For the RCS leakage detection specification, this change will eliminate the potential to ,

initiate an unnecessary unit shutdown when sufficient leak detection capability is avai3able. TVA has added expanded Bases to complete this effort to improve consistency with i NUREG-1431 for these specifications.

III. SAFETY ANALYSIS l

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Background:

Components of the SQN leakage detection system include j l containment radiation monitors, humidity monitors, a i reactor vessel flange leakoff temperature detector; I l

l condenser vacuum pump radiation monitors,. component cooling

! system radiation monitors, charging pump flow indicators,  ;

reactor building containment floor and equipment drain sump j level monitors, main steam line radiation monitors, and j safety valve and power-operated relief valve leak detection l~ and valve position monitors. These systems provide a means l of detecting, to the extent practical, leakage from the reactor coolant pressure boundary. Built-in redundancy and diversity is a key factor in the system. Various types of detectors serve to supplement one another since the range of each detector either overlaps or duplicates the range of other detectors. Detector sensitivities are such that they provide the capability to sense a leak well before the

,- leakage becomes unacceptable.

Using several types of detectors with various sensitivities result in a system more than adequate to detect abnormal l

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leakage. Multiple types of sensors assure early leak de;ection in case of failure of one or more types, thereby assuring that the necessary margin of safety will not be exceeded. The monitors credited in the accident analysis and required by the SON TSs are the containment radiation l monitors and the reactor building containment floor and i equipment drain sump level monitors.

During plant life, the component joint and valve interfaces can produce varying amounts of reactor coolant leakage through either normal operational wear or mechanical deterioration. The purpose of the RCS operational leakage LCO in TSs is to limit system operation in the presence of leakage from these sources to amounts that do not compromise safety. This LCO specifies the typc- and l

amounts of leakage.

1 The safety significance of RCS leakage varies widely depending on its source, rate, and duration. Therefore, detecting and monitoring reactor coolant leakage into the containment area is necessary. Quickly separating the identified leakage from the unidentified leakage is necessary to provide quantitative information to the operators, allowing them to take corrective action should a leak occur.

RCS pressure isolation valves are defined as any two normally closed valves in series within the reactor coolant pressure boundary, which separate the high pressure RCS from an attached low pressure system. Over time, these valves can produce varying amounts of reactor coolant leakage through either normal operational wear or mechanical deterioration. The RCS pressure isolation valve leakage requirements in the TSs allow RCS high pressure operation when leakage through these valves exists in amounts that do not compromise safety.

Although the TS requirement provides a limit on allowable pressure isolation valve leakage rate, its main purpose is to prevent overpressure failure of the low pressure portions of connecting systems. The leakage limit is an indication that the pressure isolation valves between the RCS and the connecting systems are degraded or degrading.

Pressure isolation valve leakage could lead to overpressure of the low pressure piping or components. Failure consequences could be a loss-of-coolant accident outside containment that could degrade the ability for low pressure injection.

The function of the seal injection throttle valves during I I

an accident is similar to the function of the emergency I core cooling system (ECCS) throttle valves in that each 1

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restricts flow from the centrifugal charging pump header to the RCS. The restriction on reactor coolant pump seal injection flow limits the amount of ECCS flow that would be diverted from the injection path following an accident.

This limit is based on safety analysis assumptions that are required because reactor coolant pump seal injection flow is not isolated during safety injection.

Safety Impact:

The majority of the revisions proposed in this request for RCS leakage detection, RCS operational leakage, RCS pressure isolation valve leakage, and ECCS seal injection flow do not alter the intent or the application of the current TS requirements. The purpose for these revisions is to enhance consistency with NUREG-1431. Other revisions j are proposed that provide more reasonable requirements that l are also consistent with NUREG-1431, but provide some I flexibility to the current TS requirements. One revision modifies NUREG-1431 recommendations consistent with an amendment approved by NRC for another licensee. The following discussions provide the specific impact for the revisions to each specification.

The revisions to TS 3.4.6, " Leakage Detection Instrumentation," title and LCO are editorial changes that incorporate descriptions similar to NUREG-1431. Combining l the lower containment radiation monitors into a single item l is utilized to group the two types of leak detection instrumentation together, which simplifies the application of action requirements. These changes do not impact safety because they continue to require the same diverse componente for RCS leak detection purposes that can rapidly detect small leaks.

The actions have been replaced by NUREG-1431 recommendaticns for leak detection instrumentation. These revisions implement new requirements for the complete loss of either radiation or sump level monitoring for RCS leak detection as well as loss of both functions. These actions provide more flexibility because the current action did not allow for the complete loss of the containment radiation monitors. This change is acceptable because the sump level monitoring function, along with the additional sampling requirements, continue to ensure that small RCS leaks can be detected rapidly for a limited period of time. This change also eliminates the potential to require an unnecessary unit shutdown when sufficient leak detection is available as required by Action b. The proposed Action a, for the loss of the sump level monitoring, does not alter the current requirements except for the replacement of the requirement to use containment grab samples. The El-6 o

1 requirement to take an RCS inventory balance in place of the grab samples, provides a more diverse indication of leakage in place of the inoperable sump level monitors.

The use of a grab sample would only provide compensatory monitoring equivalent to the remaining radiation monitor functions. Performance of the inventory balance or grab samples is allowed for inoperable radiation monitors in Action b because either action will provide a diverse method of leak detection and supplement the capability of the sump level monitors to detect leakage. A footnote is included for Actions a and b to allow the performance of an RCS inventory balance to be within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of steady state operation to ensure accurate results. The expectation is that the RCS balance can be accomplished with proper results within the 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> following steady state operations.

The frequency for these actions and the duration that these actions can be relied upon has not been changed.

Consistent with NUREG-1431, an exception to TS 3.0.4 is provided for Actions a and b to allow mode changes with inoperable leak detection monitors because other instrumentation is available to monitor RCS leakage. The shutdown requirements, for failure to be able to comply with the actions, have not been changed. The current immediate shutdown action for the loss of all leak detection instrumentation has been retained in the specific shutdown requirement of Action c. This requirement requires shutdown to Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. This action is more conservative than the NUREG-1431 recommendation that utilizes TS 3.0.3 for the loss of all leak detection because the initial 1-hour provision allowed prior to initiating shutdown is not utilized.

The SRs have not been changed in intent, but the wording has been modified to agree with NUREG-1431 and the changes in the LCO. These changes to Specification 3.4.6.1 will continue to provide acceptable RCS leak detection functions and appropriate actions for the inoperability of either type or both detection functions. These changes will not adversely impact nuclear safety.

The revisions to the LCO for TS 3.4.6.2, " Operational Leakage," involve the relocation of the controlled leakage requirement to new Specification 3.5.6, " Seal Injection Flow," and the pressure isolation valve requirement to new Specification 3.4.6.3, " Reactor Coolant System Pressure Isolation Valves." These relocations do not eliminate the associated requirements, but place them in specifications that are more appropriate and consistent with NUREG-1431.

The NUREG-1431 provision for primary-to-secondary leakage El-7

through all S/Gs has not been incorporated. This is based on recent NRC approved SQN License Amendments 222 and 213 for Units 1 and 2, respectively, that eliminated this provision in conjunction with S/G tube inspection and plugging methods and NRC Generic Letter 95-05. The controlled leakage definition is deleted in TS Section 1.8 and is now referred to as seal injection flow. Other definitions in Section 1.16 for identified leakage and Section 1.36 for unidentified leakage have been modified to agree with the wording in NUREG-1431 and the replacement of controlled leakage with seal injection flow. There is no change in the intent of these definitions; only the term for controlled leakage has been modified and clarifications have been incorporated as recommended in NUREG-1431.

The actions for operational leakage have not been changed.

Those actions that applied to pressure isolation valves have been relocated to Specification 3.4.6.3. No change was necessary to these actions to accommodate the relocation of the seal injection flow requirements.

The SRs have been signif_cantly revised based on the relocated portions of this specification and the recommendations of NUREG-1431. For the surveillances that are proposed for operational leakage, minor wording changes have been incorporated consistent with the NUREG, and new Surveillance 4.4.6.2.2 has been added to specifically address the primary-to-secondary leakage requirements.

This new surveillance duplicates the purpose of TS 3.4.5 and is being added to provide consistency with NUREG-1431 and future modification of the SON TSs in accordance with the standard. A footnote has been incorporated for the performance of the RCS inventory balance in Surveillance 4.4.6.2.1 that supports the performance during steady state operation and within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after establishment of steady state operation. This provision ensures that the RCS conditions are acceptable to properly obtain valid inventory balance results. Inventory balance calculations during maneuvering of the RCS parameters do not provide useful information regarding RCS leakage. The specific requirements for steady state operation is provided in the Bases for this specification. l The current Surveillances 4.4.6.2.1.a and 4.4.6.2.1.b have been deleted because the requirements for the operability of these functions are ensured by Specification 3.4.6.1 for leakage detection. These SRs are redundant to Specification 3.4.6.1 and do not provide additional benefit. Surveillance 4.4.6.2.1.c has been relocated to the seal injection flow specification. The deletion of Surveillance 4.4.6.2.1.e for monitoring reactor head flange leakoff is consistent with NUREG-1431. This surveillance El-8

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l does not provide a significant improvement in the assessment of RCS leakage in comparison to the RCS inventory balance. The leakage detection function is also fully satisfied without the use of this design feature.

While this feature does not need to be controlled by the TSs, information from this system will continue to be used for the identification of leakage and its source.

Surveillance 4.4.6.2.2 for RCS pressure isolation valves has been relocated to Specification 3.4.6.3. l I

The proposed changes to the operational leakage I requirements in Specification 3.4.6.2 will continue to provide acceptable attributes to ensure that RCS leakage is properly identified and appropriate actions are taken to minimize the impact of RCS leaks. The portions that have been relocated to new specifications will contain appropriate controls to maintain acceptable operability conditions for pressure isolation valves and seal injection flow. Therefore, the proposed revisions to Specification 3.4.6.2 will not adversely impact nuclear safety.

TVA proposes new Specification 3.4.6.3, " Reactor Coolant i System Pressure Isolation Valves," that will provide requirements previously contained in the RCS operational leakage section of the TSs. This relocation is proposed for consistency with NUREG-1431. TVA has revised the LCO for the pressure isolation valves consistent with the latest industry standard and recommendations in NUREG-1431.

The proposed LCO requires the pressure isolation valve leakage to be less than or equal to 0.5 gpm per nominal inch of valve size up to a maximum of 5 gpm. The LCO continues to require the RCS to be at nominal operating pressure of 2235 pounds per square inch gauge (psig) with a tolerance of plus or minus 20 psig. The leakage requirement provides a relaxation of the current 1 gpm limit that imposed an unjustified penalty on the larger valves without providing information on potential valve degradation. The 1 gpm limit also has the potential to increase personnel radiation exposures because the time to perform surveillance testing could be greater because of increased work activities in radiation fields. The revision to a valve size related leakage criteria is acceptable because associated systems that have larger l valves also have greater pressure relief capability. The new criteria allows for leakage above 1 gpm, although limited to a maximum of 5 gpm, because the isolated low pressure systems will not be overpressurized based on their relief capacity being greater than the allowed leakage limit. Therefore, the proposed change to the LCO will result in lower radiation exposures to personnel and a El-9 L

superior leak rate limit based on valve size as compared to a single allowable value.

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, The proposed applicability for pressure isolation valves l l has been modified for Mode 4 to provide an exception for '

l valves in the RHR flow path when in or during transition to l or from the RHR operation. This change ensures the acceptability to operate the RHR system in Mode 4 when l necessary to perform RCS heat removal. This clarification

! enhances the applicability of this specification that was not intended to restrict the use of systems that remove l decay heat and provides consistency with NUREG-1431.

The actions for pressure isolation valves have been modified consistent with NUREG-1431. Action a incorporates {

a provision that allows pressure isolation valve leakage to i be in excess of the limit for up to a total of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> provided sufficient isolation is achieved within the l initial 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of inoperability. This isolation must be achieved by a valve that has been acceptably tested to the l l same leakage requirements as the pressure isolation valves I

and be within the RCS pressure boundary. The 72-hour l completion time after exceeding the limit provides a  !

reasonable interval to restore the valve to operable status. This timeframe considers required activities to complete the action and the low probability of a second I valve failing during this period. This change will not adversely impact nuclear safety because the flow path will be sufficiently isolated at all times, and the period of time without redundant isolation capability will be i

appropriately limited. The allowance in NUREG-1431 to isolate the flow path with two valves within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and

, be permitted to operate indefinitely has not been l incorporated. This is based on the SQN design that does I

not have three or more valves within the RCS pressure boundary that could perform this capability. The addition of this provision would not be appropriate because it could not be achieved.

i Two additional actions have been added to the pressure isolation valve requirements that provide clarifications for the proper application of Action a. Action b clarifies that the actions can be entered separately for each flow path based on the functional independence of the flow paths. Action c requires entry into the actions for systems rendered inoperable as a result of the inoperable pressure isolation valve. This action requires an evaluation of systems that could be affected to ensure that the leakage has not impacted the safety function of those systems. These footnotes do not alter the application of the pressure isolation valve requirements, but serve to enhance the understanding of the expectations for applying i

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I these requirements. The NUREG-1431 recommendation to j include an action for the autoclosure interlock for the RHR '

l system has not been incorporated. This is based on NRC l approved TS Amendments 139 and 128 for Units 1 and 2, l respectively, in 1990. This amendment approved the removal of this feature because spurious actuations during periods l when RHR was required created a greater safety concern.

The SRs for the pressure isolation valves have been retained without significant modification and are consistent with NUREG-1431. The previously described exception to the TS applicability when RHR is in service is reiterated in a footnote to this surveillance to clarify that the surveillance does not apply to associated valves under this condition. Item b of the surveillance has been modified consistent with NUREG-1431 to require performance of the test if the unit has been in Mode 5 for 7 or more days. This is an extension of the current 72-hour interval that will minimize unnecessary testing for short duration unit outages. In addition, a reduction in radiation exposure to testing personnel will result by eliminating l testing activities that do not significantly enhance the l l function of the pressure isolation valves. This change is i consistent with the recommendations provided in NUREG-1366.

The current requirement to test the valves following maintenance has been omitted based on SQN maintenance practices, which are further enhanced by the implementation i of the Maintenance Rule. A similar deletion to the SON TSs l

was approved on June 13, 1995, by NRC in Amendments 203 and 193 for Units 1 and 2, respectively, where testing was required following maintenance activities. This deletion I is acceptable because maintenance practices ensure that appropriate testing is conducted following maintenance and a specific TS requirement is not necessary.

Consistent with NUREG-1431, the exception to i

Specification 4.0.4 h:s been revised to indicate that the i

surveillances are not required to be met in Modes 3 and 4.

l This provides the proper conditions to perform the surveillance and ensures that Modes 1 and 2 are not entered unless the surveillance is current. The delay in testing l the pressure isolation valves is based upon ensuring the l proper conditions exist to perform the testing and assumes that any leakage that may exist prior to the testing is I

minimal such that RCS operating pressure can be achieved without operational impact. In regards to the NUREG-1431 recommended note that minimizes repetitive testing of valves, TVA has elected to not incorporate this exception l at this time as the design and testing methodology preclude the actuation of the pressure isolation valves that have already been tested. The proposed surveillance for the RCS l pressure isolation valves and the criteria for performance l El-11 L

1 provide acceptable requirements to ensure that the leakage from these valves will not impact their operability or nuclear safety.

The proposed changes to Specification 3.4.6.3 for the RCS pressure isolation valves will continue to ensure that excessive leakage through these valves is properly identified and resnived. The surveillance will provide the )

appropriate test to detect leakage in excess of the I established limits. When these limits are exceeded, the required actions will initiate appropriate activities to minimize _the impact of the leakage. While the LCO requirement has been modified to be more reasonably based on valve size, it will continue to provide a limit that will maintain nuclear safety. Considering the SQN design features, these changes are consistent with NUREG-1431 and will not result in an adverse impact to nuclear safety.

TVA proposes new Specification 3.5.6, " Seal Injection Flow," in the ECCS portion of the TSs. These requirements have been relocated from the operational leakage requirements in the RCS portion of TSs. Placing this new specification in the ECCS section of TSs is approoriate because the seal injection flow limit is intended to ensure that ECCS flow is not diverted to a level that the safety function is degradea. The proposed LCO for this specification has been developed consistent with an NRC approved specification for the Vogtle Electric Generating Plant during their conversion to the NUREG-1431 recommendations. The proposed LCO utilizes a range of differential pressures between the charging header and the RCS and the associated acceptable seal injection flows that will support accident analysis assumptions. This relationship was evaluated and developed by Westinghouse Electric Company based on SON specific piping ,

configurations and is depicted in a figure located in the l Bases section. This approach will provide flow limits that will ensure that seal injection flows do not exceed the amounts that could degrade the ECCS function. The proposed limits are equivalent to the current 40 gpm limit, but will normally provide the ability to utilize existing plant conditions for this verification without manipulating charging header valve positions. The current requirements do not prescribe sufficient parameters to ensure that appropriate conditions are established to verify the seal injection flow resistance. The proposed revision will ,

enhance this SR by establishing a differential prescure and l the corresponding flow limit.

The applicability for this specification has been revised to delete the Mode 4 consideration and to provide consistency with NUREG-1431. This change is based on seal El-12

injection flow in Mode 4 and lower, where RCS pressure is I lower and decay heat removal requirements are reduced, not l being as critical such that ECCS functions would be i impacted. As a result, the proposed action for unacceptable seal injection flow conditions has not changed with the exception that shutdown requirements for not complying with the actions only require a mode reduction to hot shutdown rather than cold shutdown. This change is acceptable because the ECCS functions will not be adversely l impacted during Mode 4 or lower operation considering seal injection flow.

The SR for seal injection flow remains the same with only the limits of the LCO being altered. The RCS pressure l requirement for this surveillance has been clarified to l require stabilized conditions at normal RCS operating

! pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to performance. This l provision ensures that the RCS conditions are l representative and sufficiebtly stabilized to provide l accurate flow verificatior;s and the 4-hour provision will l support timely surveillance performance. This footnote l continues to satisfy the existing exclusion for Specification 4.0.4 such that entry into Mode 3 is permitted in order to establish the appropriate testing l l conditions. In addition, the position of the modulating l valve is not specified because the differential pressure requirements in the new limits are independent of the valve j position. This is because the valve is upstream of the l charging header pressure datector, and its position will i

not alter the measured differential pressure for the seal j in]ection flow limit.

The proposed specification for the seal injection flow will provide a more appropriate set of requirements to ensure that the ECCS safety functions are not impacted. The proposed requirements provide flexibility in system conditions for the verification of acceptable flow values.

This flexibility does not reduce ECCS function confidence because the same criteria is utilized in an equivalent method. This provision has been developed through an analysis of the SON system design to ensure the same level of protection is maintained. These revisions are consistent with the intent of the NUREG-1431 recommendations with a modification to the limits that have been previously approved by NRC. Therefore, the proposed specification for the seal injection flow will continue to provide appropriate requirements to maintain acceptable flows and ECCS operability.

TVA has also proposed expanded Bases for each of the TS sections described. These Bases have been developed from the Bases provided in NUREG-1431. They provide additional El-13 i

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details regarding the intent of the specifications, as well 1 as the appropriate application of the requirements. This addition will provide a clear understanding of the TS requirements and will minimize misapplication in the future. Nuclear safety will be enhanced by the l

incorporation of expanded Bases for these specifications.

IV. NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TVA has concluded that operation of SQN Units 1 and 2, in accordance with the proposed change to the technical specifications, 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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A. The propcsed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.

l The proposed revisions enhance the Technical I specification (TS) requirements to provide greater consistency with the standard TS in NUREG-1431. This revision proposes changes to the requirements for reactor coolant system (RCS) leak detection and RCS operational leakage in Specifications 3.4.6.1 and 3.4.6.2, respectively. New Specifications 3.4.6.3 and l 3.5.6 for RCS pressure isolation valves and emergency I core cooling system (ECCS) seal injection flow have l been added to improve consistency with NUREG-1431.

l The proposed revisions are not the result of changes j to plant equipment, system design, testing methods, or  !

operating practices. The modified requirements will l allow some relaxation of current operability criteria, action requirements, and surveillance requirements (SRs). These changes provide more appropriate  ;

requirements in consideration of the safety l significance and the design capabilities of the plant as determined by the improved standard TS industry effort. These specifications serve to primarily

! provide identification and control of the RCS fission l product barrier leakage and ECCS degradation and are l

not considered to be a contributor to the generation of postulated accidents. Since these proposed revisions will continue to support the required safety functions, without modification of the plant features, the probability of an accident is not increased.

The proposed changes will allow relaxation of action times for inoperable leak detection features and the components that can be inoperable. The required actions to ensure acceptable pressure isolation valve El-14

l capability with an inoperable valve have been revised

! to allow isolation by a single valve for a limited period of time. These revisions will allow unit operation for a longer period of time with reduced system redundancy. However, the redundancy reduction and action time increases are not significant and will continue to provide an acceptable level of safety I considering the significance of RCS leakage, other design features or compensatory actions that provide equivalent functions, and the unlikely chance of an l event that would require functions for leakage identification during the proposed time interval.

These considerations are consistent with the basis developed by the industry and NRC for NUREG-1431.

Surveillances have been removed from the RCS

, operational leakage specification as a result of l relocated requirements, duplication of other SRs, and l l testing requirements that do not provide a significant 1 l

benefit in the identification of RCS leakage. The SRs that have been retained or relocated to other TS specifications will provide acceptable verifications for the timely identification of conditions that indicate an unacceptable amount of RCS leakage or potential ECCS degradation resulting from excessive seal injection flow.

The limiting condition for operation associated with the seal injection flow requirements has been revised to utilize a modified operability criteria. The proposed change will provide a range of differential pressures and the corresponding seal flows that would l be representative of the existing single point flow limit. This change does not alter the intent of the operability requirements, but does allow the flexibility to use equivalent values that provide the same level of assurance for ECCS operability. The i proposed operability condition for seal injection flow enhances the current requirement by establishing additional test parameters that will ensure that the amount of seal injection flow does not degrade the ECCS functions.

The proposed changes to the SQN TS provide flexibility without modifying the functions of required safety systems. In many instances the proposed changes ensure that plant conditions for surveillance testing are more appropriate for testing purposes and the verification of system operability. These changes are consistent with the intent of NUREG-1431 and result in the enhancement of the SQN TSs based on the latest industry and NRC positions. The provisions proposed in this change request will continue to maintain an El-15

acceptable level of protection for the health and )

safety of the public and will not significantly impact the potential for the offsite release of radioactive products. The overall effect of the proposed change will result'in specifications that have equivalent or improved requirements compared to existing specifications for RCS leakage and ECCS operability and will not significantly 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 revisions are not the result of changes to plant equipment, system design, testing methods, or operating practices. The modified requirements will allow some relaxation of current operability criteria, action requirements, and SRs consistent with NUREG-1431. These changes provide more appropriate requirements in consideration of the safety significance and the design capabilities of the plant as determined by the improved standard TS industry effort. These specifications serve to primarily provide identification and control of the RCS fission product. barrier leakage and ECCS degradation and are not considered to be a contributor to the generation of postulated accidents. Since the functions of the associated systems will continue to perform without change and were not previously considered to contribute to accident generation, the proposed changes will not create the possibility of a new or different kind of accident.

C. The proposed amendment does not involve a significant reduction in a margin of safety.

The proposed changes, associated with RCS leakage and ECCS functions, will not result in changes to system design or setpoints that are intended to ensure timely identification of plant conditions that could be precursors to accidents or potential degradation of accident mitigation systems. These systems will continue to operate without change and only the associated actions or testing activities have been altered. Revisions to the actions and surveillances provide some relaxation and flexibility such that longer intervals are allowed for inoperable components and testing requirements are revised to provide conditions that provide more accurate results. The increased action times are acceptable considering the

! available redundant features, the compensatory El-16

measures provided by the actions, and the allowed time  ;

intervals that have been developed by the industry and NRC and recommended in NUREG-1431. The SR changes actually provide test condition requirements that enhance the accuracy of the activity even though they may allow a delay in the performance of the test.

These surveillance changes are also in accordance with NUREG-1431 recommendations.

These revisions will continue to provide the necessary actions to minimize the impact of inoperable equipment to an acceptable level and will provide testing activities that will ensure system operability. Since l the setpoints and design features that support the l margin of safety are unchanged and actions for inoperable systems continue to provide appropriate titue limits and compensatory measures, the proposed changes will not significantly reduce the margin of safety.

V. ENVIRONMENTAL IMPACT CONSIDERATION The proposed change does not involve a significant hazards consideration, a significant change in the l types of or significant increase in the amounts of any effluents that may be released offsite, or a significant increase in individual or cumulative j occupational radiation exposure. Therefore, the l proposed change meets the eligibility criteria for l categorical exclusion set forth in 10 CFR 51.22 (c) (9) . '

Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment of the proposed change is not required.

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