ML20198H665
| ML20198H665 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/09/1998 |
| From: | Nunn D SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML20198H613 | List: |
| References | |
| NUDOCS 9801130363 | |
| Download: ML20198H665 (13) | |
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i UNITED STATES OF AMERICA-i
-!nfCLEAR REGULATORY COMMISSION r
Applicat' ion of SOUTHERN Calif 0RNIA Dc ket No. 50 361 EDISON COMPANY, H &l...for a Class 103 License to Acquire, Possess, and Use l
a Utilization facilitv as Part of Amendment Application Unit No. 2 of the San Onofre Nuclear No. 152, Supplement.1 Generating Station SOUTHERN Calif 0RNIA EDISON COMPANY, H AL. pursuant to 10 CAR 50.90, hereby submit' Amendment' Application No. 152 i
i
~This amendment application consists of. Proposed Change Number (PCN) 451, a
Supplement I to facility Operating License No. NPF-10.
PCN 451 is a request
%g(1 to revise Unit 2 Technical Specification 3.5.1, " Safety injection Tanks," to
- 1) extend, in general, the Completion Time for a single inoperable Safety injection Tank (SIT) from I hour to 24 ' hours and 2) extend the Completion Time from 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to n hours for a single inoperable Sli when the SIT is inoperable due to malfunctioning Sli water level and/or nitrogen cover pressure instrumentation.
Supplement 1. adds a new TS 5.5.2.14. " Configuration Risk Management Program."
l The purpose of the Configuration Risk Management Prograr- (CRMP) is to ensure that a proceduralized Probabilistic Risk Assessment informeu process is in place' that assesses the overall impact of plant' maintenance on plant risk.
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Implementation of ths'CRMP will enable appropriate actions to be taken or
- decisions to-be made to minimize'and control risk when performing on-line maintenance for Systems, Structures, and Components with a risk-informed-Completion Time.
Propused '.
5.5.2.14 will be applicable to TS 3.5.1 because the_ Completion Times for TS 3.5.1 have " risk-inforr.d Completion Times."
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Respectfully submitted.
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By: h WIWitlun.
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L'N!!ED STATES Of AMERICA NUCtEAR REGULATORY QEMISSION Application of SOUTHERN Calif 0RNIA
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Docket No. 50 362 E01.30N COMPANY, H R.
for a Class 103
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License to Acquire, Possess, and Use
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a Utilization facility as Part of Amendment Application Unit No., 3 of the San Onofre Nuclear No. 136, Supplement 1 Generating Station SOUTHERN CALIFORNIA EDISON C6HPANY6 E R. pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 136.
This amendment appilcation consists of Proposed Change Number (PCN) 451, Supplement I to Facility Operating License No. NPT-15.
PCN 451 is a request l bgg L to revise Unit 3 Technical Specification 3.5.1, " Safety injection Tanks," to
- 1) extend, in general, the Cr lation Time for a single inoperable Safety Irjection Tank (SIT) from I h.. to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 2) extend the Completion Time from I hour to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for a single inoperable SIT when the SIT is inoperable due to malfunctioning SIT water level and/or nitrogen cover pressure instrumentation.
Supplen,ent I adds a new TS 5.5.2.14. " Configuration Risk Management Program."
The purpose of the Configuration Risk Hanagement Program (CRMP) is to ensure that a proceduralized Probabilistic Risk Assessment-informed process is in place that assesses the overall impact of plant mainterance on plant risk.
Implementation of the CRMP will enable appropriate actions to be taken or sq,1 decisions to be made to mir,imize and control risk when performing on-line maintenance for Systems, Stru:tures, and Components with a risk-informed Completion Time.
Proposed TS 5.5.2.14 will be applicable to TF 3.5.1 because the Completion Times for TS 3.5.1 have " risk-informed Completion Times."
l day of b k lll W ld
,1998.
f Subscribed on this i
J Respectfully submitted, SOUTHERN CALIFORNIA EDISON COMPANY t
By
(
Dwight Nunn )
Vice Presiden
. State pf Ca'ifornia fore at
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-acknowledged to me. net he executed the same in his authortred capacity, and that by his signature on the instrument the person, or the entity upon behalf f which the person acted, executed the instrument.
WITNESS and and official seal
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ENCLOSURE (PCN451, Supplement 1) p I
'O OlbCRIPTION AND 5AFETY ANALYSIS r
0F PROPOSED CHANCE NPF-10/15 451, SUPPLEMENT 1 l 5*tP 1 This is & requ'est to revise the San Onofre Units-2-and 3 Technical-Specification (TS)k M6nagement Program."
3.b.1, " Safety injection Tanks" and add a new TS 5.5.2.14,
" Configuration Ris gID t Existino Specificating Unit 2:-
See Attachment "A" Unit 3:
See Attachment "B" froposed Specifications Unit 2:
See Attachment "C*
Unit 3:
See Attachment "0" DESCRIPTIONOFPR0ff,EDCHANGES In Technical Specification (TS) 3.5.1, " Safety injection Tanks:"
o' The Completion Time for a single inoperable Stfety Injection Tank (SIT) is extended from I hour to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the 517 is determined to be incperable due to Sli water level and/or SIT nitrogen cover pressure being outside the prescribed limits.
o The Completion Time for a single inoperdle SIT is extended from I hour to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> when the SIT water level or SIT nitrogen cover pressure or both cannot be verified due to malfunctioning S?T water level or SIT nitrogen cover pressure instrument indications, included in /ttachment "C" for Unit 2.and Attachment "0" for Unit 3, re::pectively, are revised TS page 3.51 and Bases pages B3.5 7 through B3.540a.
Supplement I adds a new TS 5.5.2.14, " Configuration Risk Management Program."
The purpose of the Configuration Risk Management Program (CRMP) is to ensure placethroceduralizedProbabilisticRiskAssessment-informedprocessisin that a -
at assasses the overall impact of plant maintenance on plant r sk.
S 1-Implementation of the CRMP will enable appropriate actions to be taken or q
decisions to be made to minimize and control risk when performing on-line maintenance for Systems, Structures and Components with a risk-informed Completion Time.
Proposed TS 5.5.2.14 will be applicable to TS 3.5.l'because the Completion Times for TS 3.5.1 have risk infor,aed Completion Times.
(
DACKGROUNJ The SITS are passive _ pressure vessels partially filled with borated water and
-pressurized with a cover of nitrogen gas to facilitate injection into the-reactor-. vessel during the blowdown phase of a large break Loss.of Coolant
' Accident (LOCA). This Sli. injection of borated water provides -inventory to l591 assist-in accomplishing the refill stage following blowdown. The SITS also provide Reactor Coolant System (RCS) makeup for small break LOCAs.
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Each' SIT-is connected to an associated RCS cold leg by way of an Emergency Core Cooling System (ECCS) line, which is also utilized by the High Pressure
-Safety injection (HPSI) system and the Low Pressure Safety Injection (LPSI) system. - Each $1T is isolated from the RCS, during normal operations,' by two eneck valves in series.
Each SIT discharge has a normally oaen and-deenergized motor operated isolation valve used to isolate tie SIT from the RCS during normal depressurization and cooldown evolutions.
The FIT gas pressure and volume, water volume, and outlet piping are designed to allow three of the four SITS to inject the inventory necessary to keep clad melt'and zirc-water reaction within design assumptions following a design basis LOCA. The design assumes the loss of inventory from one SIT via the LOCA break.
The ECCS is described in Section 6.3 with the SITS specifically riescribed in Section_6.3.2.2.1 of the San Onofre Units 2 and 3 Updatert final Safety Analysis Report (UFSAR).
QECUSSION Of CHANE Industry operating experience has demonstrated that many of the causes of SIT inoperability have been diagnosed and corrected within a relatively short period of time, but often longer than the existing I hour Completion Time.
In several instances, diagnosis of an inoperable SIT has resulted in plant shutdowns. A review of this operating experience, as well as a general review of existing Probabilistic Risk Assessment (PRA) studies, led to questioning whether transitioning to a lower mode as required by the existing TS action provide 3 greater reactor safety than remaining at power and repairing the inoperable SIT.
If a single SIT were to be diagnosed as inoperable for reasons other than due ta boron _ concentration being outside the limits established by the San Onofre Units 2 and 3 TS 3.5.1, the SIT must be restored to operable status within one hour or the plant must be in at least Hot. Standby within.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and the pressurizer pressure reduced to less than 715 psia within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The proposed change to TS 3.5.1 would allow continued operation up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, in lieu of I hour, to restore the SIT to operable status if the inoperability of the SIT is determined to be due to-the inability to verify water level or nitrogen cover pressure or both. - The proposed TS change also allows up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, in lieu of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, to restore a single SIT to operable status if the S:T is declared inoperable for any reasons other than the reasons mentioned above'.-
The Combustion Engineering Owners Group (CE0G) Report CE NPSD-994, " Joint Applications-for_ Safety injection Tank Completion Time /STI Extension," has
-demonstrated risk calculation., associated with an Completion Time extension
>from one hour;to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The results of the analyses indicate that the average single and yearly Completion Time risk contributions are negligible and the average core damage frequencies (CDFs) are-virtually unchanged.
The data and risk-results in CE NPSD-994 pertaining to the San Onofre units.were supplied and endorsed-by Southern-California Edison.
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The' risk assessment performed by the CEOG in CE NPSD 994 evaluated "at
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risk," " transit' ion risk," " shutdown risk," and "large early release ris(." At power risk represents the risk associated with continued operation with a single SIT out of service.- Transition risk represents thc risk associated with reducing power and placing the plant in a Hot or Cold Shutdown mode i
following equipment failure. Shutdown risk benefits were not credited for tbo j
Sli Completion Time extension.
The results of this analysis indicate that the i
average core damage probability (CDP) attributable to transition risk is larger than the average CDP associated with continued power operation of the plants with one Si? inoperable for the proposed Completion Time.
As part'of the CEOG study an: assessment was performed on the impact of the proposed Completion Time extension on large early release scenarios. The three classes of events considered for these release scenarios include: Class
'l event category (containment bypass); Class 2 event category (severe accidents accompanied by loss of containment isolation; and Class 3 event zategory (containment failure associated with energetic events in the
- containment).
The assessment concluded that tha unavailability of one Sli would not impact or alter the progression of Class 1 events since thet,e events are characterized by an irrevocable loss of reactor inventory along with any makeup outside of containment. A small increase in Class 2 events could occur when an unmitigated large break LOCA occurs in conjunction with an initially unisolated containment.
There will be no significant fission product releases unless the containment is unscrubbed (containment sprays are inoperable).
This later combination of class 2 events is considered of very low 3robability.
Class 3 events are dominated by RCS transients that occur at ligh pressure.
These events exclude those where SIT performance would be called for and therefore Sli status is not a contributor to this event categey.
Therefore, the assessment concluded that the unavailability of one SIT will result in-a negligible impact on the large early release probability for San Onofre.
TS.3.5.1 does not differentiate between a SIT that is inoperable due to tank inventory or nitrogen gas pressure discrepancies-and a SIT whose inventory or gas pressure cannot be verified due solely to malfunctioning water level instrumentation or pressure instrumentation or both.
Because these instruments provide no safety actuation, it is reasonable to extend the Completion Time since the SIT is available to perform its safety function during this time.
This proposed change is in accordance with the provisions of NUREG 1366, " Improvements to Technical Specifications Surveillance Requirements," and Generic letter 93 05, "Line Item imprevements to Reduce Surveillance Requirements for Testirig During Power Operation."
The CEOG study concluded that the overall plant risk with this proposed Completion _. Time is either risk beneficial or, at the very least, risk neutral.
The Surveillance Test Interval (STI) portion of CE NPSD-944 deals with boric
' acid concentration-sampling surveillance requirements. A change to the boron
' sampling requirements, which eliminates'a.,urveillance when the SIT makeup water is from the Refueling Water Storage Tank (RWST), was evaluated and endorsed by the NRC in NUREG 1366. - This change is already incorporated in the
. Improved Standardized Technical Specifications for San Onofre Units 2 and 3.
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o 10 ensure plant safety is maintained and monitored San Onofre will implement a Configuration Risk Management Program (CRMP) which is to be applicable to TS 3.5.1.
1.
Purpose of CRMP l
The purpose of the Configuration Risk Management Program (CRMP) is to ensure that a proceduralized Probabilistic Risk Assessment (PRA)-
informed process is in place that assesses the overall impact of plant maintenance on plant risk.
Implementation of the CRMP will enable appropriate actions to be taken or decisions to be made to minimize and control risk when performing on-line maintenance for Systems.
-Structures, and Components (SSCs) with a risk-informed Completion Time.
2.
Scope of CRMP
/
The scope of the SSCs included in the CRMP are those SSCs considered High Safety Significant por the Maintenance Rule regulatory guide (Regulatory Guide 1.160 Rev. 2).
The Configuration Risk Management Program (CRMP) includes the following components and key elements:
Components 1
a.
Risk Assessment Tool b.ff1, b.
Tier 2 restrictions c.
Level 2 and External Events d.
Decision Making Frecess e.
Associated Procedures Key Element 1.
Implementation of CRMP The intent of the CRMP is to implement a(3) of the Maintenance Rule (10CFR50.65) with respect to on line maintenance for risk informed technical specifications, with the following additions /
clarifications:
a.
The-scope of SSCs to be included in the CRMP will be the SSCs considered High Safety Significant per Regulatory Guide 1.160, Rev. 2.
- b. -
The CRMP assessment tool is PRA informed, and may be in the form of cither a risk matrix, an on line ass.ssment, or a direct PRA assessment.
c.
CRMP will be invoked as follows for:-
Risk-Informed inoperabilityr A risk assessment will be performed pricr to entering the LCO Condition for preplanned activities.
For unplanned entry into the LC0 Condition, a risk assessment will be' performed in a timeframe consistent with the plant's Corrective Action Program.
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Additional 55C Inoperability and/or Loss of Functionality:
When in the risk informed Completion Time, if an additional
-high safety significant SSC becomes inoperable /non functional, a risk assessment shall be performed in a timeframe consistent with the plant's Corrective Action Pragram, d.
Tier 2 commitments apply for planned maintenance only, but will be evaluated as part of the Tier 3 assessment for unplanned occurrences.
Key Element 2.
Control & Use of the CRMP Assessment Tool a.
Plant modifications and procedure changes will be monitored,-
assessed, and dispositioned.
Evaluation of changes in plant configuration or PRA model features can be dispoi,itioned by implementing PRA model 1
changes or by the qualitative assessment of the impact of the changes on the CRMP assessment tool. This qualitative assessment recognizes that changes to the PRA take time tr implement and that changes car be effectively compensated for without compromising the ability to make sound engineering judgments.
Limitations of the CRMP assessment tool are identified and i
understood for each specific Completion Time extension.
b.
Procedures exist for the control and application of CRMP assessment tools, includin description of process when outside the scope of the CkMP assessment tool, b"f f' 1 Key Element 3.
Level 1 Risk-Informed Assessment The CRMP assessment tool is based on a level 1, at power, internal events PRA model. The CRMP assessment may use any combination of quantitative and qualitstive input. -Quantitative assessments can include reference to a risk matrix, pre-existing calculations, or new PRA analyses, a.
r;uantitative assessments should be performed whenever necessary for sound decision making.
o.
When quantitative assessments are not necessary for sound decision making, qualitative assessments will be performed.
Qualitative assessments will consider applicable, existing insights from quantitative assessments previously performed.
Key Element 4.
Level 2 Issues / External Events External events and Level 2 issues are treated qualitatively and/or quantitatively.
Guidance for implementing the CRMP is provided by plant procedures.
5 N.
y, SAFETY ANALYSlS, lhe proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any one of the following areas:
1.
Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No The Safety injection Tanks (SITS) ato passive components in the Emergency Core Conling System (ECCS).
The SITS are not accident initiators in any accident previously evaluated.
Therefore, this change does not involve an increase in the probability of an accident previously evaluated.
The SITS are designed to mitigate the consequences of loss of Coolant Accidents (LOCAs). The proposed changes do not a Uect any of the assumptions used in deterministic LOCA analysis.
Therefore, the consequences of accidents previously evaluated do not change.
To fully evaluate the Sli Completion Time extension, Probabilistic Safety Analysis (PSA) methods were utilized. The results of these analyses show no significant increase in core damage frequency. As a result, there would be no significant increase in the consequences of an
' accident previously evaluated.
T I
The proposed change pertaining to SIT inoperability based solely on instrumentation malfunction does not involve a significant increase in the consequences of an accident as evaluated and endorsed by the Nuclear e
in NUREG-1366, " Improvements to Technical Regulatory Commission (NRC) Requirements."
Specifications Surveillance The Configuration Risk-ilanagement Program is an Administrative Program i
that assesses risk based on plant status. Adding the requirement to 591 implement this program for Technical Specification 3.5.1 does not affect the probability or the consequences of an accident.
Therefore, this chango does RD1 involve a significant increase in the probability or consequences of any accident previously evaluated.
Will operation of the facility in accordance with this proposed change
- 2. -
create the possibility of a new or different kind of accident-from any accident-previously evaluated?
. Response: No ibis proposed change does not change the design, configuration, or
-method of operation of the plant.
Therefore, this change does agi create the possibility of a new or different kind of accident from any
'previously evaluated.
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3.
Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?
i Response: No The )roposed changes do not affect the limiting conditions for operation or t1eir bases that are used in the deterministic analyses to establish the margin of safety.
PSA evaluations were used to evaluate these changes. These evaluations demonstrate that the changes are either risk neutral or risk beneficial.
Therefore, this change doer Q21 involve a significant reduction in a margin of safety.
Safety and Sianificant Hazards Destrmjnation BLsed on the above Safety Analysis, it is concluded that: 1) thr. proposed change does not constitute a significant hazards ccnsideration at defined by i
10 CFR 50.92 and 2) there is reasonable assurance that the health and safety of the pub 1'.c will not be endangered by the proposed change. Moreover, because this action does not involve a significant hazr ds consideration, it i
will also not result in a condition which significantly alters the impact of the station on the environment as described in the NRC Final Environmental Statement.
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r ATTAcilMENT "A" EXISTING TECilNICAL SPECIFICATIONS
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