ML20116F042

LAR 96-006 to Licenses NPF-87 & NPF-89,increasing Allowed Outage Time for Charging Pump from 72 H to 7 Days

ML20116F042
Person / Time
Site:	Comanche Peak
Issue date:	08/02/1996
From:	Terry C, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20116F045	List: ML20116F042 ML20116F047
References
TXX-96434, NUDOCS 9608060211
Download: ML20116F042 (10)

Text

!

l l

Nmm- Log # TXX 96434

'0' -

==

' File # 916 (3/4.1)

_~ 916 (3/4*.5)  ;

r

=-

10010 l Ref # 10CFR50.90  !

7UELECTR/C' 10CFR50.36 C. Lance Terry c,,.,va,rins,m August 2. 1996 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) UNITS 1 AND 2 DOCKET NOS. 50 445 AND 50 446 '

SUBMITTAL 0F LICENSE AMENDMENT REQUEST 96 006 INCREASE IN ALLOWED OUTAGE TIME FOR A CHARGING PUMP FROM 72 HOURS TO 7 DAYS e Gentlemen:

Pursuant to 10CFR50.90, TV Electric hereby requests an amendment to the CPSES Unit 1 Operating License (NPF 87) and CPSES Unit 2 Operating License (NPF-89) by incorporating the attached changes into the CPSES Units 1 and 2 Technical Specifications. These changes will increase the allowed outage time (A0T) for a centrifugal charging pump from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days for CPSES Units 1 and 2.

Technical Specification Limiting Condition for Operation (LCO) 3.1.2.4 is revised by changing the ACTION statement to allow a centrifugal charging pump to be out of service for 7 days. LC0 3.5.2 will be revised by adding a new ACTION statement which would allow a centrifugal charging pump to be out of service for 7 days.

Attachment 1 is the required affidavit. Attachment 2 provides a detailed description of the proposed changes, a safety analysis of the proposed changes and TU Electric's determination that the proposed changes do not involve a significant hazard consideration. Attachment 3 provides the affected technical specification pages marked up to reflect the proposed changes.

l TU Electric requests review and approval of these changes 18 months from the date of issuance of this letter with implementation to occur within 30 days of approval.

L 9600060211 960802 I PDR ADOCK 05000445 } }

P PDR l i

Energy Plaza 1601 Bryan Street Dallas, Texas 75201-34l 1

)'

.. TXX'.96434

• Page 2 of 2 In accordance with 10CFR50.91(b), TV Electric is providing the State of Texas with a copy of this proposed amendment.

Should you have any questions, please contact Mr. Jimmy Seawright at (214)

812 4375 or Mr. Don Woodlan at (214) 812 8225.

Sincerely.

l C. L. Terry By: M 8*

RogeruD.' Walker Regulatory Affairs Manager i

JDS/grp Attachments:

1. Affidavit

2. Description and Assessment l 3. Affected Technical Specification pages as 1 l

revised by all approved license amendments c: Mr. L. J. Callan. Region IV i Hs. L. Smith, Region IV {

l Mr. T. J. Polich, NRR i Resident Inspectors '

Mr. Arthur C. Tate l l Bureau of Radiation Control l l Texas Department of Public Health i

1100 West 49th Street Austin, Texas 78704 i

l 4

I i )

l l

1 l

1

! . Attachment 1 to TXX 96434 Page'l of 1 i

UNITED STATES OF AMERICA  !

NUCLEAR REGULATORY COMMISSION In the Matter of ) i

)

Texas Utilities Electric Company ) Docket Nos. 50-446 l

) 50-446 l (Comanche Peak Steam Electric ) License Nos. NPF 87 j Station Units 1 & 2) ) NPF-89  ;

AFFIDAVIT Roger D. Walker being duly sworn, hereby deposes and says that he is Regulatory Affairs Manager of TU E'lectric, that he is duly authorized to sign and file with the Nuclear Regulatory Commission this License Amendment Request 96-006; that he is familiar with the content thereof: and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.

l l

09% 1 Roger"D. Walker Regulatory Affairs Manager i l

STATE OF TEXAS )

)

COUNTY OF DALLAS )

Subscribed and sworn to before me, a Notary Public, on this 2nd day of Auaust ,1996.

- ~

bi Notary u lic b

,p*' 4 }

Gayle R. Peck l, *

! Notary Puge,stete of ya >

W Comm. hpires 01/06/98 l

i

l e

4 ATTACHMENT 2 TO TXX 96434 I DESCRIPTION AND ASSESSMENT i

1 i

l l

i l

Attachment 2 to TXX 96434 Page'l of 5 l l

i DESCRIPTION AND ASSESSMENT I

I. BACKGROUND I

The affected Technical Specifications are 3/4.1.2.4, " CHARGING PUMPS -

OPERATING," AND 3/4.5.2, "ECCS SUBSYSTEMS - T,y > 350 F. " Currently, these specifications allow a centrifugal charging pump to be inoperable for an allowed outage time (A0T) of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. In response to recent failures of charging / safety injection pump shafts (Information Notice 94 76), TU i Electric has prepared preplans for replacing the rotating element of a l centrifugal charging pump. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed outage time is not  !

sufficient to accomplish such emergent repairs on an inoperable centrifugal l charging pump. i The proposed change will increase the allowed outage time for a centrifugal charging pump from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days. The 7 days is judged sufficient to perform most repairs (including replacing a rotating element) on an inoperable centrifugal charging pump and could avoid an unnecessary plant shutdown without a significant effect on the health and safety of the public. The proposed changes are changes to plant specific values, justified by plant specific analyses and, as such, do not represent changes in the improved Standard Technical Specifications for Westinghouse Plants.

NUREG 1431.

l l

II. DESCRIPTION OF TECHNICAL SPECIFICATIONS CHANGE REQUEST l The proposed amendment would modify Technical Specification Limiting Condition for Operation (LCO) 3.1.2.4 by revising the ACTION statement to allow a centrifugal charging pump to be out of service for 7 days. LC0 3.5.2 would be revised by adding a new ACTION statement 'a' which would allow a centrifugal charging pump to be out of service for 7 days. ACTION

'b' would be modified to exclude an inoperable centrifugal charging pump from the ACTION for an ECCS subsystem inoperable.

III. ANALYSIS The proposed change would increase the A0T from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days for one centrifugal charging pump declared inoperable while in MODES 1, 2, 3 or 4.

Because compliance with the Technical Specifications LCOs preserves the assumptions of the accident analyses, the proposed change has no ef fects on the accident analyses. Only one train is required to successfully meet the assumptions of the accident analyses. Therefore, the effect of the proposed change can be considered in a probabilistic manner in order to assess the potential effects on the health and safety of the public. The centrifugal charging pumps are part of the fully redundant ECCS.

Attachment 2 to TXX 96434 Page 2 of 5 Increasing the A0T of the centrifugal charging pump from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days would potentially increase the unavailability of the centrifugal charging pumps. The centrifugal charging pump unavailability is categorized by maintenance unavailabilities and random failures of the centrifugal charging pumps. Both of these unavailabilities were considered in this analysis.

The average maintenance unavailability of centrifugal charging pumps is the product of:

the frequency of entering the ACTION statement for maintenance and repair of the pump and the average duration of the maintenance / repair.

The average maintenance unavailability of a centrifugal charging pump, as used in the CPSES Individual Plant Examination, is 1.75E 3 (i.e., about 0.2 percent). Increasing the A0T would have no impact on the frequency of maintenance and repair, but it may affect the average duration of the maintenance / repair activity. Most of the maintenance / repair situations where the ACTION statement is entered result in using less than the currently allowed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Increasing the A0T from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days should not result in a proportional increase in the average duration of maintenance and repair. Many of the maintenance / repairs would still be of short duration. However, for this analysis, the maintenance duration was increased based on the data correlation between duration and A0T, a factor that is slightly greater than the A0T ratio.

The change does not significantly affect the availability of the ECCS functions for accident saitigation. A calculation was performed in which the impact of the increased unavailability was evaluated, using the existing fault tree analysis for ECCS injection and recirculation functions during a loss of-coolant accident (LOCA). This assessment was conservative and bounding in rature. It was assumed that the centrifugal charging pump unavailability (and failure probabilities) increased proportionately to the ir. crease in A0T for all failure modes except corrective maintenance.

Corrective maintenance was assumed to increase by a larger amount based on the data correlation between outage duration and A0T.

The analysis shows a 17.3% increase in the CCP injection unavailability and a 9.1% increase in CCP recirculation unavailability. However, the ECCS functions were deemed the most appropriate functions to consider because of the equivalence of the CCPs and SI for these functions. The results of the reanalysis of ECCS injection for LOCA mitigation, using the increased charging system unavailabilities, show an increase of 5.2 percent. ECCS recirculation shows an increase of 3.0 percent. These changes are insignificant. The primary reasons for the relatively small increases are that:

the assumed unavailability of the centrifugal charging pumps attributed to maintenance and repair is low.

i 1 Attachment 2 to TXX 96434 Page 3 of 5 the overall unavailability of the charging system is dominated by failure modes such as valve failures and postulated common mode failures in the probabilistic risk assessment (PRA) model, and contributors other than centrifugal charging pump maintenance unavailability.

The impact of the change on the estimated core damage frequency (CDF) has been evaluated. For internal events, the CDF would conservatively increase by 4.60E 7/yr, less than 1 percent of the current (internal events) CDF of 5.72E 05/yr from the Individual Plant Examination (IPE). It is  !

conservative because the value is based on the assumption that all centrifugal charging pump outages are increased by at least the A0T ratio.

This increase has an insignificant impact. Random failures are only of "significant" concern during the maintenance / repair outage on a redundant train-or component. This remains relatively unchanged by the A0T extension. For the infrequent occasions where one might expect to enter the ACTION statement for greater than the currently allowed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the centrifugal charging pump in the opposite train would be available. To analyze this, random failure probabilities were also increased by the A0T ratio. The difference in failure to-run probability between 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and 7 days for the charging pump in the opposite train is low 3.28E-3. The increase in the frequency of loss of all centrifugal charging pump events was determined to be negligible. Therefore, the change would have no measurable impact on normal plant operations.

The charging system unavailability was also examined to determine the impact of this extended A0T on the reactor coolant pump (RCP) seal cooling function. RCP seal injection via charging, or RCP thermal' barrier cooling via component cooling water, is required to maintain RCP seal integrity.

The increase in the charging system unavailability was found to be insignificant. The evaluation found the impact of the change on the probability of RCP seal cooling function failure to be insignificant -(1.e.,

a very small change in the failure probability of RCP seal injection via charging and no effect on RCP thermal barrier cooling via component cooling water).

An evaluation was also performed to determine the CDF due to external events (fire, tornado, seismic). The CDF due to external events is generally dominated by an external event-induced loss of support systems, ,

in combination with insufficient time to perform operator actions, or l random failure of support equipment. For these events, it is concluded l that the increase would be approximately 6.40E-07/ reactor year, or 2 to 3 l percent of the current external events CDF. Thus, the increased A0T would 4 have small impact on the CDF and a change of this magnitude is not considered to be significant.

This license amendment request is being proposed by TU Electric to reduce

, the risk of an unnecessary plant shutdown to perform centrifugal charging l pump repairs. Use of PRA insights constitutes the principle justification for this proposed change. This approach.is consistent with one of the

! philosophies put forth in the Commissions' Final Policy Statement on l Technical Specification Improvements for Nuclear Power Reactors. In part,

1 I

Attachment 2 to TXX-96434 Page 4 of 5 1 the final policy statement says ". . . the Commission . . . will continue I to consider methods to make better use of risk and reliability, information for defining future generic Technical Specification requirements." (July j

22. 1993, 58FR39138). We believe this proposed amendment is an appropriate <

application of this concept. 1 IV. SIGNIFICANT HAZARDS CONSIDERATION TV Electric has evaluated whether or not a significant hazards consideration is involved with the proposed changes by focusing on the three standards set forth in 10CFR50.92 as discussed below:

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated? i There is no effect on the probability of an event: the only potential effect is on the capability to mitigate the event. The centrifugal charging pumps are credited in the Final Safety Analysis Report Chapter 15 LOCA analysis for ECCS injection and for the containment sump recirculation mode for the design basis LOCA. Increasing the A0T for the centrifugal charging pumps does not affect analysis assumptions regarding functioning of required equipment designed to mitigate the consequences of accidents. Further, the severity of postulated accidents and resulting radiological effluent releases will not be affected by the increased A0T.  ;

A reliability analysis of the charging system found the change to have i no significant impact on normal operation or on the RCP seal cooling function. Therefore, the change would not significantly increase in the probability of a seal LOCA.

The change potentially affects only the availability of the charging system for accident mitigation and has no effect on the ability of other ECCS systems to perform their functions. Through the use of a probabilistic risk ascessment, it was determined that the proposed change would have an insignificant effect on the core damage frequency.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do L.ne proposed changes create the possibility of a new or different type of accident from any accident previously evaluated?

Unavailability of one centrifugal charging pump for a finite period of time is currently allowed by the Technical Specifications. Increasing the A0T from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days would not change the method that TU Electric operates CPSES, thus would not create a new condition.

Further, the proposed change would not result in any physical alteration to any plant system, and there would not be a change in the method by

l Attachment 2 to TXX-96434 Page 5 of 5 which any safety related system performs its function. The ECCS would still be c'pable of mitigating the consequences of the design basis accident LOCA with the one centrifugal charging pump operable. No new 1

unanalyzed accident would be created.

3. Do the proposed changes involve a significant reduction in a margin of sa fety?

The proposed change does not impact either the physical protective boundaries or performance of safety systems for accident mitigation.

There is no safety analysis impact since the extension of the centrifugal charging pump A0T interval will have no effect on any safety limit, protection system setpoint, or limiting condition of operation.

There is no hardware change that would impact existing safety analysis

, acceptance criteria, therefore there is no significant change in the l margin of safety.

In summary, the proposed change would not have a significant impact on the margin of safety.

Based on the above evaluations, TV Electric concludes that the activities associated with the proposed changes satisfy the no significant hazards l consideration standards of 10CFR50.92 and accordingly, a no significant j hazards consideration finding is justified.

l l

V. ENVIRONMENTAL EVALUATION TV Electric has determined that the proposed amendment would change requirements with respect to the installation or use of a facility component located within the restricted area, as defined in 10CFR20, or would change an inspection or surveillance requirement. TU Electric has determined that the proposed amendment does not involve (1) a significant hazards consideration (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed change meets

! the eligibility criterion for categorical exclusion set forth in 10CFR51.22(c)(9). Therefore, pursuant to 10CFR51.22(b), an environmental assessment of the proposed change is not required.

I I

l l

4

• l l

f I l I

ATTACHMENT 3 TO TXX-96434 I

\

AFFECTED TECHNICAL SPECIFICATION PAGES I

l l

l l

,