ML20045F393

Safety Evaluation Supporting Amend 160 to License DPR-61

ML20045F393
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	06/28/1993
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20045F344	List: ML20045F343 ML20045F392 ML20045F393
References
NUDOCS 9307070261
Download: ML20045F393 (5)

Text

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El NUCLEAR REGULATORY COMMISSION 3m g

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\\.....f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 160 10 FACILITY OPERATING LICENSE NO. DPR-61 CONNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT DOCKET NO. 50-213

1.0 INTRODUCTION

By letter dated April 30, 1993, as supplemented May 26, 1993, the Connecticut Yankee Atomic Power Company (CYAPCO, the licensee) submitted a request for changes to the Haddam Neck Plant Technical Specifications (TS). The requested changes would modify Technical Specification 3/4.8, " Electrical Power Systems," paragraph 4.8.1.1.2.b, to reflect a design change that would change the allowable elapsed time for the automatic load sequencer for the " backup" containment air recirculation (CAR) fans to 5 minutes i30 seconds from 48 seconds 15 seconds. The amendment would also make two editorial changes to amend the wording of " Backup" to "Second Containment Recirc. Fan" and add "First" to the beginning of " Containment Recirc. Fan" on the previous line.

The May 26, 1993, letter provided clarifying information that did not change the initial proposed no significnat hazards consideration determination.

2.0 EVALUATION As a result of Inspection Report No. 50-213/91-80, the licensee determined the need to address diesel loading concerns particularly in the first minutes following an accident.

A significant engineering review effort was required to address this issue.

CYAPC0 reevaluated the existing mass-energy release calculations to determine boundaries for isolating emergency core cooling loads.

The results of this reevaluation were reviewed for impact on containment analysis.

Based on these reviews, CYAPC0 determined that the emergency diesel generator (EDG) loading of the CAR fans could be modified and still maintain the conservative approach to accident mitigation and containment response.

The motive for this modification is to decrease the EDG loading for the first few minutes of EDG operation during an accident scenario. This modification will improve the EDG loading profile during such an event, will alleviate the operators from having to manually start the second CAR fan, and provide annunciation to the operators to verify the start of the second CAR fans at 5 9307070261 930628 PDR ADOCK 05000213 p

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. minutes and to start the third fan at 10 minutes if necessary. To fulfill the current safety analysis assumptions, one CAR fan must be operational within 1 minute from receipt of a safety injection actuation signal (SIAS), two CAR fans within 10 minutes, and a minimum of three CAR fans within 15 minutes from SIAS.

The proposed modification will maintain these criteria. Therefore, in both the current and the modified design, the minimum allowed time for operator action is 10 minutes (either manual action to start the second and third CAR fans in the current design, or to start the third fan in the new design).

As part of the EDG loading concerns, CYAPC0 performed a walk-through of the emergency operating procedures (EOPs) to determine the approximate times for manual sequencing of the CAR fans onto the EDG for the worst case (loss of one diesel).

Based on this walk-through CYAPC0 stated that the first fan would be automatically loaded at 43 seconds, the second fan manually loaded at 1 minute and the third fan manually loaded at 3 minutes. The plant assumes the operators would load the CAR fans as-soon-as-possible.

Loading of the fans is a simple operation only requiring the operation of a single switch.

In i

addition, loading of a third CAR fan onto one diesel requires one additional action of turning a key-locked switch, which is located on the panel above the CAR fan switches.

Based on the above, the staff concludes the licensee has demonstrated that CAR fan operation is a simple operation and achievable within staff guidelines for operator action.

The current TS require that the first CAR fans for each diesel are given a signal to start at 43 seconds.

If the first CAR fan fails to start the second CAR fan on that diesel is given an automatic signal to start at 48 seconds.

There are three scenarios to be considered in this change: (1)

Both diesels start, (2) single failure of one CAR fan, and (3) single failure of one diesel.

Each scenario is discussed below:

Both Diesels Start As currently designed, one CAR fan would be automatically loaded on each diesel at 43 seconds. As noted above, the E0Ps only inform the operator that a third CAR fan must be loaded within 15 minutes.

The plant assumes the operators would load the CAR fans as-soon-as-possible.

Based on a walk-through of the E0Ps for CAR fan operation, the third CAR fan would be manually loaded within 2 minutes after a SIAS. With the modification, one CAR fan would be automatically loaded on each diesel at 43 seconds and at 5 minutes a second CAR fan would be automatically loaded on each diesel.

In addition.the modification will provide annunciation at 5 minutes for the operators to verify the second CAR fans have been started and at 10 minutes to start the third fan if necessary.

The staff agrees that the modification in this case assures CAR fans actuation is well within the required FSAR assumptions, is more restrictive, and enhances safety as no manual action is now required and all four CAR fans are started in 5 minutes.

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t i Sinale Failure of One CAR Fan As currently designed, one CAR fan would be automatically loaded on each diesel at 43 seconds and if a CAR fan were to fail the second CAR fan would be automatically loaded at 48 seconds.

As noted above, the E0Ps only inform the operator that a third CAR fan must be loaded within 15 minutes. The plant assumes the operators would load the CAR fans as-soon-as-possible.

Based on a walk-through of the E0Ps for CAR fan operation, the third CAR fan would be manually loaded within 3 minutes after a SIAS, independent of whether it was the first or second CAR fans that failed. With the modification, one CAR fan would be automatically loaded on each diesel at 43 seconds and whether the first CAR fan started or not, at 5 minutes the second CAR fans would be 3

automatically loaded on each diesel.

Therefore, whether a first CAR fan or a second CAR fan failed, three CAR fans would be started in 5 minutes.

In addition, the modification will provide annunciation at 5 minutes for the operators to verify the required CAR fans have been started and at 10 minutes to start the third fan if necessary.

The staff agrees that the modification in this case assures CAR fans actuation is well within the required FSAR assumptions, is more restrictive, and enhances safety as no manual action is now required.

Sinale Failure of One Diesel The most limiting case is the failure of one diesel.

As currently designed, one CAR fan would be automatically loaded on the operable diesel at 43 seconds. As noted above, based on a walk-through of the E0Ps for CAR fan operation, the second and third CAR fans must be manually loaded and all three fans would be loaded in 3 minutes.

With the modification, one CAR fan would be automatically loaded on the operable diesel at 43 seconds and at 5 minutes the second CAR fan would be automatically loaded.

At 5 minutes after the SIAS, the E0Ps instruct the operators to verify the second CAR fan has started and then instructs the operators to start the third CAR fan between 10 and 15 minutes.

In addition, the modification will provide annunciation at 5 minutes 3

for the operators to verify the required CAR fans have been started and at 10 minutes to start the third fan.

In either the current or the modified design, the minimum allowed time for operator action is 10 minutes (either manual action to start the second CAR fan in the current design or to start the third fan in the new design).

Based on the walk-through the licensee has demonstrated that loading of the second and third CAR fans assuming one operable diesel is achievable within the 15 minute FSAR assumptions. The staff agrees that the modification in this case assures CAR fan actuation is i

well within the required FSAR assumptions and is bounded by the original design as the modified system requires less operator action and the operator has been provided with annunciators to assure the CAR fans are loaded. The delay of the CAR fan starting decreases EDG loading at a critical time and significantly improves the EDG loading profile therefore enhancing safety.

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t Based on the above, the staff has concluded that the modifications to the diesel load sequencers will increase the degree of automatic function, reduce r

the reliance on operator action, and significantly improve the EDG loading i

profile during the first few minutes of operation. The licensee notes that the current EDG loading profile approaches the 30 minute load rating from approximately 3 minutes, when three CAR fans have been loaded on one diesel, until at 11 minutes after SIAS when the low pressure safety injection (LPSI) pumps are stopped. With the modification, the EDG loads would approach the 30 minute load rating for only about I minute (see Table 1). Therefore, the staff finds the proposed TS change request acceptable.

Wordina Chanae The amendment would also make two editorial changes to amend the wording of

" Backup" to "Second Containment Recirculation Fan" and add "First" to the beginning of " Containment Recirc. Fan" on the previous line in TS section 4.8.1.1.2.b.

The staff has reviewed these changes and conclude that they are editorial in nature and the changes are acceptable.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment.

The State official had no comments.

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4.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.

The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 30191). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

5.0 CONCLUSION

4 The Commission has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such i

activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

A. Wang Date: June 28, 1993 i

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