ML20095L016
| ML20095L016 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/19/1995 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20095L021 | List: |
| References | |
| NUDOCS 9512290388 | |
| Download: ML20095L016 (11) | |
Text
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South'fr Nuctur.Dptrhting Como:ny l Post Offica Box 1295
- Birmingham, Alabtma 35201 i Telephone (205) 868 5131 i V
- o. . uo,.r Southem Nudear Operating Company I
$r*efr*r$e*ct the southem electnc system December 19, 1995 50-364 U. S. Nuclear Regulatory Commission ATTN.: Document Control Desk Washington, D.C. 20555 Joseph M. Farley Nuclear Plant Request to Revise Technical Specifications Control Room Emeraency Ventilation System Ladies and Gentlemen-In accordance with the provisions of 10 CFR 50.90, Southern Nuclear Operating Company (Southern Nuclear) proposes to amend the Joseph M. Farley Nuclear Plant Units 1 and 2 Technical Specifications. The changes are found in section 3/4.7.7, Control Room Emergency Ventilation System, and its associated Bases for the Unit I and Unit 2 Technical Specifications. The proposed changes replace the requirements associated with the Control Room Emergency Ventilation System with requirements related to the operation of the Control Room Emergency Filtration / Pressurization System (CREFS) and Control Room Air Conditioning System (CRACS). These technical specification changes are technically consistent with the requirements of NUREG-1431, Revision 1,
" Westinghouse Standard Technical Specifications," issued on April 7,1995.
In addition to the permanst technical specification changes included with this request, a one-time extension to the allowable outage time for the control room recirculation filtration system is included to facilitate implementation of design modifications to enhance the reliability of the control room air conditioning system during the Spring of 19%.
Approval of the one time request will allow an enhancement to overall plant safety by I facilitating system upgrades that cannot be accomplished within the existing Limiting Condition for Operation (LCO) time.
The basis for the proposed technical specification changes is provided in Enclosure 1.
The supporting significant hazards evaluation pursuant to 10 CFR 50.91 is provided in Enclosure 2. Based upon the analysis provided, Southern Nuclear has determined the l proposed changes to the technical specifications do not involve a significant hazards consideration as defined by 10 CFR 50.92. Southern Nuclear has determined that the proposed license amendment will not significantly affect the quality of the human environment.
The revised typed pages of the proposed technical specifications, including page change instructions, are included in Enclosure 3. The marked pages are provided in Enclosure 4.
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9512290388 951219 PDR N '
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,- U. S. Nuclear Regulatory Commission Page 2 The Plant Operations Review Committee has reviewed and recommended approval of these proposed changes. A copy of these proposed changes is being sent to Dr. Donald E. Williamson, the Alabama State Designee, in accordance with 10 CFR l 50.91(b)(1).
In order to facilitate implementation of the design enW=ments planned for the control room air conditioning system during the Spring of 1996, NRC review and approval of these technical specification changes is requested by March 1996. Southern Nuclear requests that the effective date for the proposed amendment occur when the applicable LCOs are entered for design change implementation. The functional operability tests that will be performed at the conclusion of the installation of the new air conditioning systems will serve as the initial surveillance To facilita'e review of this submittal, many aspects of this request are similar to the License Amedment Nos. 23 and 9 for the Comanche Peak Steam Electric Station, Units 1 and 2, granted on April 6,1994. In addition, a one time extension similar to this Southern Nuclear request was granted for McGuire Nuclear Station by License Amendments Nos.140 and 122 dated Febmary 10,1994.
If there ata any questions, please advise.
Sincerely, SOUTHERN NUCLEAR OPERATING COMPANY
~
b hm Dave Morey SWORN TO AND SUBSCRIBED BEFORE ME This /N Dayofdd,1995.
&b[A dh Notary Public My Commission Expires: 7/ M 3,l'/f7
! DPH.maf CRVTSI. DOC Enclosures
, 1. Basis for Change Request i 2.10 CFR 50.92 Evaluation
- 3. Page Change Instructions and Revised Pages
- 4. Hand-Marked Pages cc: B. L. Siegel, Licensing Project Manager, NRR S. D. Ebneter, Regional Administrator i T. M. Ross, Senior Resident Inspector Dr. D. E. Williamson, State of Alabama l s ,
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.. .. 1 j . ENCLOSURE 1 )
Joseph M. Farley Nuclear Plant i i Request to Revise Technical Specifications i Control Room Emergency Ventilation System
- I Basis for Permanent Channe Reautg 1
i The proposed changes would revise Technical Specification (TS) 3/4.7.7 and its l associated Bases by replacing the requirements associated with the Control Room
- Emergency Ventilation System with requirements related to the Control Room Emergency Filtration / Pressurization System (CREFS) and Control Room Air Conditioning System l (CRACS). The proposed changes are technically consistent with the requirements of the
- improved Westinghouse Standard Technical Specifications (STS) (NUREG-1431, 1 i Revision 1) issued on April 7,1995.
l The Control Room Emergency Ventilation System at Farley Nuclear Plant, referred to as the control room emergency air cleanup systems, is shared by Units 1 and 2. The ;
- emergency air cleanup systems are required to be operable during all modes of operation.
1 The current limiting condition for operation allowed outage time of 7 days is not a consistent with the low probability ofloss of all control room cooling, including the failure l of the redundant train, with consideration given to the mitigative actions of the operators ]
to respond manually to limit control room heat-up. The present Limiting Condition for !
Operation (LCO) restriction could result in the simultaneous shutdown of both units due to the loss of one air conditioning unit.
4 In the present TS 3/4.7.7, the requirements for the control room emergency air cleanup systems are divided into two different Actions based on the units' operating mode The
[ proposed changes will separate the requirements into two specifications based on the overall system functions. TS 3/4.7.7.1 will address the filtration / pressurization aspects of i
the control room emergency air cleanup system and TS 3/4.7.7.2 will address air conditioning. In the proposed revision, a new specification for the Control Room Air Conditioning System (CRACS) is provided and the existing specification is essentially l transferred to the Control Room Emergency Filtration / Pressurization System (CREFS).
j For the cooling functions, the existing action statement is changed from an allowed outage
- time (AOT) of 7 days to an AOT of 30 days. The 30 days is acceptable W=> it takes j into account the fact that following a loss of the CRACS, temperature changes are gradual, dependent upon outside temperature, and time is available for manual actions that can alleviate the loss of CRACS. A sensitivity analysis has been performed which has l determined that various operator actions can be taken which would extend the time to t
reach the control room component qualification temperature of 120*F. Procedures will be m place to take these actions should they be necessary.
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ENCLOSURE 1 Basis for One-Time Change to Recirculation Filtration System AOT The control room air conditioning system presently includes two trains of cooling, each with a single 100 percent capability cooling unit. Modifications are planned that will result -l I
in installation of two 100 percent capacity cooling units for each train. During the time of cooling system installation, the duct work for the ventilation system will require substantial modification. The duct work for the CRACS also serves the recirculation filtration system. As a result, ahhough no changes to the filtration system are planned, a single train of recirculation filtration will be inoperable during the CRACS modifications for each train. In order to facilitate the CRACS enhancements, a one-time change is requested to extend the AOT for each train to 30 days.
It should be noted that the control room pressurization system, including intake air filtration, for FNP is independent of the CRACS and the recirculation filtration system.
Accordingly, the AOT extension for the recirculation filtration system will not affect the )
capability of the pressurization system to maintain a positive pressure in the control room I and to filter outside air in the event of an accident.
The requested change will extend the time period during which single failure capability for the recirculation fdtration system is unavailable, from the 7 days presently allowed by TS to 30 days on a one-time basis. The recirculation filtration system is only required in l response to an accident that results in core damage and a large airborne release.
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I A review of the Farley Nuclear Plant Units 1 and 2 Individual Plant Examination Report (IPE) prepared in response to Generic Letter 88-20 was conducted to determine the relative risk significance of this one-time change. Table 4.4-7 of the IPE identifies the FNP Airborne Release Categories. With regard to a planned outage on the control room l l recirculation filtration system, the release categories of concern would be those which result in early containment releases that would not allow time for compensatory measures
- in the event of random failure of the operable filtration system. These release categories are identified as categories T and G in Table 4.7-7. The total release frequency from these
! categories is 5.189E-07 per reactor-year. For the planned CRACS replacement evolution of 60 days, this represents a conditional probability of a core damage event occurring l
- resulting in a fission product release in categories T and G of 8.53E-08 per unit. Since the control room recirculation filter units are shared between units, the total release j probability is twice the per unit value or 1.71E-07. It should be stressed that this is not an
- increase in release probability, but is the conditional probability of a core damage event resulting in an early release occurring within the 60 day period ofinterest.
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August 1995) was reviewed to provide a relative assessment of the risk significance of this one-time change. In accordance with the EPRI PSA Application Guide criteria, a temporary increase in Large Early Release Probability (LERP) ofless than 1.0E-07 should J be considered non-risk significant. With a LERP between 1.0E-07 and 1.0E-06, other i non-quantitative factors should be evaluated which may indicate that the evolution could !
be justified as non-risk significant. Although the case under review does not represent an !
increase in release probability, it does represent a potential increase in the dose to the control room personnel following an event. An increase in control room dose received by ;
the operators would only occur if the operable control room Sltration system failed. The l actual probability of failure of the single operable control room filtration system concurrent with a large early release would be smaller than 1.0 E-07, even assuming a conservatively high failure probability of 0.5. Actual failure history of this system is much lower. On this basis, the proposed one-time Technical Specification change would be considered non-risk significant.
Although the probability of occurrence of an event involving an increase in dose to the control room operators is extremely low, FNP will take reasontble measures to limit the unavailability of the recirculation filtration system during the modification. This will be l accomplished through established means such as detailed planning of the work sequence, I prefabrication of components and staging of parts. In addition, control room operators will be briefed on mitigative actions that may be taken in the unlikely event of an accident involving a radioactive release and the accompanying failure of the available train of recirculation filtration. These measures include donning Siter masks (respiratory protection) as immediate compensatory action and the use of portable recirculation filters j that are presently available on-site. ,
On this basis it may be concluded that the one-time AOT extension for each train of recirculation filtration has an insignificant impact on the safety and health of the public. In addition, there is no significant increase in risk of exposure of control room operators in response to any design basis accident.
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4 ENCLOSURE 2 Joseph M. Farley Nuclear Plant Request to Revise Technical Specifications Control Room Emergency Ventilation System 10 CFR 50.92 Evaluation Pursuant to 10 CFR 50.92 each application for amendment to an operating license must be reviewed to determine if the proposed change involves a significant hazards consideration. The amendment, as defined below, describing the Technical.
Specifications changes to the Control Room Emergency Ventilation System has been reviewed and deemed not to involve significant hazards consideration. The basis for this '
determination follows.
BACKGROUND The Control Room Emergency Ventilation System at Farley Nuclear Plant (FNP),
referred to as the control room emergency air cleanup system, is shared by Units 1 and 2.
The emergency air cleanup systems are required to be operable during all modes of operation. The current Limiting Condition for Operation (LCO) allowed outage time (AOT) of 7 days is not consistent with the low probability ofloss of all control room cooling, including the failure of the redundant train, with consideration given to the mitigative actions of the operators to respond manually to limit control room heat-up.
This restriction could result in the simultaneous shutdown of both units due to the loss of one air conditioning unit.
i In addition to the permanent change associated with the control room air conditioning -
system AOT, a one-time extension to the AOT for each train of the recirculation filtration portion of the Control Room Emergency Filtration / Pressurization System (CREFS) is
- requested to facilitate implementation of design enhancements to the Control Room Air Conditioning System (CRACS).
Farley Nuclear Plants design is similar to the Westinghouse plant design on which NUREG-1431, Revision 1," Standard Technical Specifications Westinghouse Plants,"is j based. As such, Farley N.uclear Plant desires to utilize the AOTs for the control room air conditioning portion of the system as allowed by NUREG-1431, Revision 1. In conjunction with this change, Farley Nuclear Plant is adopting the content of these Standard Technical Specifications for the CREFS and the CRACS.
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ENCLOSURE 2
, 10 CFR 50.92 Evaluation -
The Farley Nuclear Plant design consists of a common control room for both units with two independent trains of control room air conditioning, filtration and pressurization.
Each train is capable of performing 100% of the control room environmental controls with the loss of the other train. Modifications are planned that will result in installation of two 100 percent capacity cooling units for each train.
DESCRIPTION OF CHANGE REOUEST The proposed changes would revise Technical Specification (TS) 3/4.7.7 and its associated Bases by replacing the requirements associated with the Control Room Emergency Ventilation System with requirements related to the Control Room Emergency Filtration / Pressurization System (CREFS) and Control Room Air
' Conditioning System (CRACS). The proposed changes are technically consistent with the requirements of the improved Westinghouse Standard Technical Specifications (STS)
(NUREG-1431, Revision 1) issued on April 7,1995. Current Farley Technical Specification requirements are also included in the proposed amendment for filter testing.
In the present TS 3/4.7.7, the requirements for the control room emergency air cleanup systems are divided into two different Actions based on the units' operating mode. The proposed changes will separate the requirements into two specifications based on the overall system functions. TS 3/4.7.7.1 will address the filtration / pressurization aspects o'i the control room emergency air cleanup system and TS 3/4.7.7.2 will address air conditioning. In the proposed revision, a new specification for Se Control Room Air Conditioning System (CRACS) is provided and the existing specifications are essential:y transferred to the Control Room Emergency Filtration / Pressurization System (CREFS)
The changes reorganize the requirements of the control room emergency air cleanup system based on function rather than unit operating mode, adopt the 30 day AOT for the
, cooling ftmetions per NUREG-1431, Revision 1, and make other detailed changes to the
- specification technically consistent with the equivalent specifications in NUREG-1431,
- Revision 1.
In addition, the existing TS 3.7.7(c) statement that "the provisions of Specification 3.0.3 are not applicable in Mode 6,"is deleted. This statement is not included in NUREG-1431 and is considered extraneous in that 3.0.3 provides no guidance associated with Mode 6.
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4 ENCLOSURE 2
, 10 CFR 50.92 Evaluation The control room air conditioning system presently includes two trains of cooling, each with a single 100 percent capability cooling unit. Modifications are planned that will result in installation of two 100 percent capacity cooling units for each train. During the time of cooling system installation, the duct work for the ventilation system will require substantial modification. The duct work for the CRACS also serves the recirculation filtration system. As a result, although no changes to the filtration system are planned, a single train of recirculation filtration will be inoperable during the CRACS modifications for each train. In order to facilitate the CRACS enhancements, a one-time change is requested to extend the AOT for each train of recirculation filtration to 30 days.
ANALYSIS The action statement for the emergency filtration / pressurization functions (CREFS),
while in MODES 1,2,3, and 4 remains unchanged in the proposed revision.
The action requirement for the CREFS while in MODES 5 and 6 with one train inoperable has been changed to clarify an alternative action which may be taken following the AOT. The new alternative action is to suspend core alterations and the movement of spent fuel assemblies. This is an acceptable alternative because the function of the CREFS during these modes is to protect against'a fuel handling accident. I For two CREFS trains inoperable, the action requirement has also been changed to j suspend core alterations and the movement ofirradiated fuel assemblies.
For the cooling functions (CRACS), the existing action statement for Modes 1,2,3, and 4 is changed from an AOT of 7 days to an AOT of 30 days. The 30 days is acceptable because it takes into account the fact that following a loss of the CRACS, temperature changes are gradual, dependent upon outside temperature, and time is available for manual actions that can alleviate the loss of CRACS A sensitivity analysis has been performed which has determined that various operator actions can be taken which would
- extend the time to reach the control room component qualification temperature of 120 F.
, Procedures will be in place to take these actions should they be necessary. The 30-day l AOT is also consistent with the Westinghouse STS (NUREG-1431, Revision 1). These times are also acceptable for the Farley Nuclear Plant design and manual actions are available to compensate for a complete loss of CRACS.
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- The action requirements for the CRACS while in MODES 5 and 6 with one train inoperable has been changed to an AOT of 30 days. Following the AOT, an alternative action to suspend core alterations and the movement ofirradiated fuel assemblies has j j been added. l 1
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ENCLOSURE 2
- 10 CFR 50.92 Evaluation This same alternative action is required when both trains of CRACS are inoperable.
These changes are acceptable for the same reasons identified previously for the CRACS .
in MODES 1 through 4 and for the CREFS in MODES 5 and 6. These changes are also consistent with NUREG-1431, Revision 1.
NUREG-1431, Revision 1, Section 5 has provisions for a ventilation filter testing program. Since changes are not being made to the existing Administrative Sections of the Farley Technical Specifications, the existing Farley Technical Specification surveillance requirements for the CREFS filters have been included in the revised technical specification. This approach is in lieu of a statement that the filters will be tested in accordance with the ventilation filter testing program as specified in NUREG-1431, Revision 1. The frequency and methods of testing the CREFS and CRACS are similar to other safety-related systems and are consistent with the requirements in NUREG-1431, Revision 1. Additionally, the guidance provided in NUREG 1431, Revision I has already received the requisite review and approval of the NRC staff.
Modifications are planned that will result in installation of two 100 percent capacity cooling units for each train of the CRACS. During the time of cooling system installation, the duct work for the ventilation system will require substantial modification.
In order to facilitate the CRACS enhancements, a one-time change is requested to extend the AOT for each train to 30 days. De requested change will extend the time period ;
during which single failure capability for the recirculation filtration system is unavailable from the 7 days presently allowed by TS to 30 days on a one-time basis, ne
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recirculation filtration system is only required in response to an accident that results in core damage and a large airborne release.
It should be noted that the control room pressurization system, including intake air filtration, for FNP is independent of the CRACS and the recirculation filtration system.
Accordingly, the AOT extension for the recirculation filtration system will not affect the capability of the pressurization system to maintain a positive pressure in the control room )
and to filter outside air the event of an accident.
)
A review of the Farley Nuclear Plant Units 1 and 2 Individual Plant Examination Report (IPE) prepared in response to Generic Letter 88-20 was conducted to determine the relative risk significance of this one time change. The FNP IPE identifies the Airborne Release Categories. With regard to a planned outage on the control room recirculation filtration system, the release categories of concem would be those which result in early containment releases which would not allow time for compensatory measures in the event of random failure of the operable l
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ENCLOSURE 2
. 10 CFR 50.92 Evaluation filtration system. The total early release frequency from these categories is 5.189E-07 per reactor-year. For the planned CRACS replacement evolution of 60 days, this represents a conditional probability of a core damage event occurring resulting in an early fission product release of 8.53E-08 per unit. Since the control room recirculation filter units are shared between units, the total release probability is twice the per unit value or 1.71 E-07.
It should be stressed that this is not an increase in release probability, but is the conditional probability of a core damage event resulting in an early release occurring within the 60 day period ofinterest.
The EPRI Probabilistic Safety Assessment (PSA) Application Guide (EPRI TR-105396, August 1995) was reviewed to provide a relative assessment of the risk significance of this one time change. In accordance with the EPRI PSA Application Guide criteria, a temporary increase in Large Early Refease Probability (LERP) ofless than 1.0E-07 should be considered non risk significant. With a LERP between 1.0E-07 and 1.0E-06, other non-quantitative factors should te evaluated which may indicate that the evolution could bejustified as non-risk significant. Although the case under review does not represent an increase in release probability, it does represent a potential increase in the dose to the control room personnel following an event. An increase in control room dose received by the operators would only occur if the operable control room filtration system failed. The actual probability of failure of the single operable control room filtration system concurrent with large early release would be smaller than 1.0 E-07, even assuming a conservatively high failure probability of 0.5. Actual failure history of this system is much lower. On this basis, the proposed one-time Technical Specification change would be considered non-risk significant.
! Although the probability of occurrence of an event involving an increase in dose to the l
control room operators is extremely low, FNP will take reasonable measures to limit the unavailability of the recirculation filtration system during the modification. This will be accomplished through established means such as detailed planning of the work sequence, prefabrication of components and staging of parts. In addition, control room operators will be briefed on mitigative actions that may be taken in the unlikely event of a an accident involving a radioactive release and the accompanying failure of the available train of recirculation filtration. These measures include donning filter masks (respiratory protection) as immediate compensatory action and the use of portable recirculation filtration units that are presently available on-site. J On this basis it may be concluded that the one-time AOT extension for each train of l recirculation filtration has an insignificant impact on the safety and health of the public.
In addition, there is no significant increase in risk of exposure of control room operators in response to any design basis accident.
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3 i , ENCLOSURE 2 l 10 CFR 50.92 Evaluation i
10 CFR 50.92 EVALUATION CONCLUSIONS Based on the preceding evaluation, the following conclusions are provided with respect to the criteria contained in 10 CFR 50.92.
(1) The proposed changes do not significantly increase the probability or consequences
. of and accident previously evaluated in the FSAR. The proposed changes have no 1
impact on the probability of an accident. The control room ventilation systems are
- support systems which have a role in the detection and mitigation of accidents but 4 do not contribute to the initiation of any accident previously evaluated.
I Reorganizing the technical specifications by functions have no impact on the course of any accidents previously evaluated. The other changes which are being made improve the ability to mitigate fuel handling accidents. Specifying an allowed outage time (AOT) of 30 days for the cooling of recirculated air while one train is inopemble is based on the significance of the cooling function but does represent an increase in the allowed outage time and thus an increase in the probability that the J
functions could be unavailable, nis increase is not considered significant based on several factors including: the design is based on the worst postulated meteorological
. conditions; generally, less than design cooling is required and a partial failure in the system may have no impact; and unavailability failure does not create an immediate i irreversible impact (i.e., temperature will increase slowly over a period of time); the 4
' system could be restored or its loss mitigated without any impact on the ' course or whatever accident is being considered; and the extended AOT would allow more i opportunity to perform major required maintenance and thus may provide an overall improvement in equipment reliability, i
, In addition, the one-time change to the AOT for the recirculation filtration will not
- significantly increase the probability or consequences of an accident due to the low l probability of an event result in an airborne release of radioactivity. Such an event
! requires multiple failures of safety systems that are govemed by technical
, specifications not affected by these changes. In addition, compensatory measures
. have been identified that limit the potential exposure of control room operators in response to a postulated release.
- The net effect of these changes is not significant and, as a result, the changes do not i involve a significant increase in the consequences of an accident previously evaluated.
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ENCLOSURE 2
. 10 CFR 50.92 Evaluation (2) The proposed changes to the Technical Specifications do not increase the possibility of a new or different kind of accident than any accident already evaluated in the FSAR. No new limiting single failure or accident scenarios have been created or identified due to the proposed changes. Safety-related systems are expected to perform as designed. Although the changes could have a minor impact on the air conditioning system availability, the changes do not create the possibility of a new or different kind of accident from any previously evaluated.
(3) The proposed changes do not involve a significant reduction in the margin of safety.
The changes proposed do not alter the environmental conditions which are to be maintained in the control room during normal operations and following an accident.
As a result, the margin of safety for these functions remains the same. Although there is a potential impact on the air conditioning system's postulated availability, there is no impact on the accident analyses. Further, although the one-time AOT extension for the recirculation filtration system increases the system unavailability during the planned CRACS design changes, the net effect is a benefit to plant safety due to the enhancement to control room cooling capability. Thus, even if system availability issues were considered an aspect of margin of safety, the proposed changes do not involve a significant reduction in the margin of safety.
Accordingly, Southern Nuclear has determined that the proposed changes with respect to )
the Control Room Emergency Ventilation System do not involve a significant hazards consideration.
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