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Application for Amend to License DPR-61,proposing Rev to TS by Increasing AOT for Charging Pump from 72 Hours to Seven Days
	ML20059G582
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	11/02/1993
From:	Opeka J; CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST UTILITIES
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20059G585	List: B14619, Proposed Tech Specs Increasing AOT for Charging Pump from 72 Hours to Seven Days; ML20059G582;
References
	B14619, NUDOCS 9311080245
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4 NORTHEAST UTILITIES o ner i Omco. seia.n street. Bornn. conn.ct,cui S'

HARTFOR CONNECTICUT 06'141-0270 a

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(203) 665-5000 j-1 I

I November 2, 1993

.[

t Docket No. 50-213 B14619 l

Re:

10CFR50.90 i

U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 j

i Gentlemen:

Haddam Neck Plant Proposed Revision to Technical Specifications Emeroency Core Coolina Systems i

Pursuant to 10CFR50.90, Connecticut Yankee Atomic Power Company (CYAPCO) i hereby proposes to amend its Operating License, DPR-61, by incorporating the changes identified in the attachments into the Technical Specifications of the Haddam Neck Plant.

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Description of Proocsed Chanaes Currently Technical Specification 3.5.1, "ECCS Subsystems - T,., Greater Than or Equal to 350*F," allows an emergency core cooling system (ECCS) sub ystem t

to be inoperable for a period of. un to.72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Haddam Neck Plant's specific i

experience has shown the 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months may not be sufficient to accomplish certain 4

repairs, such as rotating assembly repair 'or complete pump replacement, on an J

inoperable charging pump.

This proposed license amendment will increase the allowed outage time (A0T) for a charging pump from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days.

I The seven days is judged sufficient to-repair an inoperable charging pump and would avoid an unnecessary plant shutdown.

Specifically, the proposed amendment would modify Techniccl-Specification 3.5.1, limiting Condition for Operation, by adding a new ACTION statement 'a' which would allow a charging pump to be out of service for seven -

i days.

ACTION statement 'b' will be modified to clarify its applicability. to.

i the high-pressure safety injection pumps, low-pressure safety injection pumps, and residual heat removal (RHR) pumps and RHR heat exchangers.

The remaining ACTION statements have been relettered to accommodate the new ACTION 'a.'-

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U.S. Nuclear Regulatory Commission B14619/Page 2 November 2, 1993 Safety Assessment The proposed change would increase the A0T from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days for one centrifugal charging pump declared inoperable while in MODES 1, 2, or 3.

Based on historical data, the average unavailability of a centrifugal charging pump is 1.03E-2 (i.e., about 1 percent).

Increasing the allowed outage time of the centrifugal charging pump from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days would theoretically increase the unavailability.

The average unavailability of the charging pump is the product of:

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

Increasing the A0T would have no measurable impact on the frequency or maintenance and repair.

Most of the maintenance / repair situations where the ACTION statement is entered result in using less than the full 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months allowed.

Increasing the A0T from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days would not necessarily result in a proportional increase in the average duration of maintenance and repair.

Many of the maintenance / repairs would still be of short duration.

For the infrequent occasions where one might expect to enter the ACTION statement for greater than the currently-allowed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , the redundant centrifugal charging pump would be available.

The difference in failure-to-run probability between 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and seven days for the redundant charging pump is very low, 5.4E-3.

The increase in the frequency of loss of all centrifugal charging pump events would be low, of the order of less than once per hundred years.

Therefore, the change would have no measurable impact on normal plant operations.

'Ibe proposed change does not impact the physical protective boundaries nor does it affect the performance of safety systems.

The change does affect the availability of the charging pumps for accident mitigation.

A calculation was performed that evaluated the impact using the existing fault tree analysis for the charging injection and recirculation functions during a loss-of-coolant accident (LOCA).

This assessment was conservative and bounding in nature.

It assumed that the historical charging system unavailability of 1.03E-2 (per pump) increased proportionately to the increase in A0T.

The results of the reanalysis of the charging system unavailabilities for LOCA mitigation for ECCS injection shows an increase of 0.3 percent (from 5.84E-3

U.S. thuclear Regulatory Comission B14619/Page 3 November 2, 1993 to 5.86E-3).

ECCS recirculation shows an increase of 4.3 percent (from 6.88E-3 to 7.17E-3).

These changes are considered very small.

The primary reasons for the relatively small increase are that:

the unavailability of the charging pumps owing to maintenance and repair is currently very low, the overall unavailability of the charging system is dominated by failure modes, such as valve failures, postulated comon mode failures in the probabilistic risk assessment (PRA) model, and contributors other than charging pump maintenance unavailability.

The reanalysis also indicated that core melt frequency (CMF) due to internal events increased by 3.0E-7/yr or less than 1 percent of the current (internal events) CHF of 1.8E-4/yr.

The charging system unavailability was also examined to determine the impact of this extended A0T on the reactor coolant i

pump (RCP) seal cooling function.

Again, the increase in the charging system unavailability was found to be insignificant.

A qualitative evaluation was also performed to determine the CMF due to external events (fire, tornado, seismic), and it was concluded that the increased A0T would have insignificant impact on the CMF. The CMF, 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 random failure of support equipment.

CYAPC0 has found that the increase in the charging pump allowed outage time from three days to seven days is acceptable.

This license amendment request is being proposed by CYAPC0 to reduce the risk of an unnecessary plant shutdown to perform charging 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 Comissions' Final Policy Statement on Technical Specification Improvements for Nuclear Power Reactors.

In part, the final policy statement says "...

the Comission... will continue to consider methods to make better use of risk and reliability, information for defining future generic Technical Specification requirements." (July 22, 1993, 58FR39138).

We believe this proposed amendment is an appropriate application of this concept.

i Sionificant Hazards Consideration In accordance with 10CFR50.92, CYAPC0 has reviewed the attached proposed changes and has concluded that they do not involve a significant hazards consideration (SHC). The basis for this conclusion is that the three criteria I

P D.S. Nuclear Regulatory Commission B14619/Page 4 November 2, 1993 of 10CFR50.92(c) are not compromised.

The proposed changes do not involve an SHC because the changes would not-1.

Involve a sianificant increase in the orobability or conseouences of an accident oreviously evaluated.

It should be noted that the charging pumps are not credited in the Updated Final Safety Analysis Report Chapter 15 LOCA analysis for ECCS injection because they are not automatically loaded onto the emergency diesel generators for coincident LOCA and loss of offsite power.

The pumps are credited for the containment sump recirculation mode for the design-basis LOCA.

The potential impact of the proposed change on the RCP seal cooling function has been evaluated.

RCP seal injection via charging, or RCP thermal barrier cooling via component cooling water, is required to maintain RCP seal integrity.

Failure of RCP seal cooling could, at worst, result in RCP seal leakage and loss of reactor coolant system inventory (i.e., small LOCA).

The evaluation found the impact of the change on the RCP seal cooling function to be insignificant (i.e., below the threshold of measurement in the PRA model).

Therefore, the change will have no effect on the probability or occurrence of previously evaluated accidents.

The change affects only the availability of the charging system for accident mitigation.

Therefore, there is no effect on the consequences of previously evaluated accidents.

2.

Create the oossibility of a new or different kind of accident from any accident oreviously evaluated.

Unavailability of one centrifugal charging pump for a finite period of time is currently allowed by the technical specifications.

The unavailability of one centrifugal charging pump is bounded by the assumptions in the current LOCA analysis.

Increasing the A0T from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days would not create a new condition.

The ECCS would 1

still be capable of mitigating the consequences of the design-basis accident LOCA with the one centrifugal charging pump inoperable.

No new unanalyzed accident would be created.

3.

Involve a sionificant reduction in a maroin of safety.

[

The proposed change does not impact the physical protective boundaries nor performance of safety systems for accident mitigation.

The global impact of the change on the estimated CMF has been evaluated.

For internal events, the CMF would increase by a theoretical maximum of

i I

0.S. Nuclear Regulatory Commission B14619/Page 5 November 2, 1993 3E-7/yr, which is much less than I percent of the current value. This is an insignificant impact.

It is a theoretical maximum because the value assumes that all charging pump outages during Modes 1, 2,

and 3 are increased by the factor 7/3, which is very conservative.

The potential impact on external events (e.g., fire, tornado) was also assessed.

The effect on CMF was found to be even less significant than for internal events.

In summary, the proposed change would have no impact on the margin of safety.

Moreover, the Commission has provided guidance concerning the application of standards in 10CFR50.92 by providing certain examples (March 6,

1986, 51FR7751) of amendments that are considered not likely to involve an SHC.

Although the proposed changes are not enveloped by a specific example, they do not involve an SHC because they do not involve a significant increase in the probability or consequences of an accident previously analyzed, create the i

possibility of a new or different kind of accident from that previously analyzed, or involve a significant reduction in the margin of safety.

A reliability analysis of the charging system found the change to have no measurable impact on normal operation nor on the RCP seal cooling function.

There would be no increase in the probability of a LOCA. The change only increases the A0T of the centrifugal charging pump.

The impact of one centrifugal charging pump out of service is currently bounded by assumptions i

within the existing LOCA analysis.

The reliability analysis of the charging system found the theoretical impact of increasing the A0T for one centrifugal charging pump to be very small.

CYAPC0 has reviewed the proposed license amendment against the criteria of 10CFR51.22 for environmental considerations.

The proposed changes do not involve an SHC, do not increase the types and amounts of effluents that may be released off-site, nor significantly increase individual or cumulative occupational radiation exposures.

Based on the foregoing, CYAPC0 concludes i

that the proposed changes meet the criteria delineated in 10CFR51.22(c)(9) for categorical exclusion from the requirements for an environmental impact statement.

t The retype of the proposed changes to the technical specifications in Attachment I reflects the - currently issued version of the technical i

specifications.

CYAPC0 hereby requests the NRC Staff to check for continuity with the technical specifications prior to issuance.

The marked-up copy of -

the technical specifications are contained in Attachment 2.

Revision bars are provided in the right-hand margin to indicate a revision to text.

No revision bars are utilized when the page is changed solely to accommodate the shifting of text due to additions or deletions.

The Haddam Neck Plant Nuclear Review Board has reviewed and approved this proposed amendment and concurs with the above determination.

U.S. Nuclear Regulatory Comission B14619/Page 6 l

November 2, 1993 In accordance with 10CFR50.91(b), we are providing the State of Connecticut with a copy of this proposed amendment.

t Regarding our proposed schedule for this amendment, we request issuance at your earliest convenience with the amendment effective as of the date of issuance, to be implemented within 30 days of issuance.

t Very truly yours, l

CONNECTICUT YANKEE ATOMIC POWER COMPANY

- b b id"b J. F. Opeka>

u Executive Vice President cc:

T. T. Martin, Region I Administrator A. B. Wang, NRC Project Manager, Haddam Neck Plant W. J. Raymond, Senior Resident Inspector, Haddam Neck Plant Mr. Kevin T. A. McCarthy, Director Monitoring and Radiation Division Department of Environmental Protection 79 Elm Street P.O. Box 5066 Hartford, CT 06102-5066 Subscribed and sworn to before me this f

I day of /Nwdev,1993

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