ML20004D937

Forwards Draft Safety Evaluation Re SEP Topic VI-7.B, Engineered Safety Features Switchover. Requests Review & Submittal of Comments within 30 Days

ML20004D937
Person / Time
Site:	Yankee Rowe
Issue date:	06/04/1981
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Kay J YANKEE ATOMIC ELECTRIC CO.
References
TASK-06-07.B, TASK-6-7.B, TASK-RR LSO5-81-06-013, LSO5-81-6-13, NUDOCS 8106100351
Download: ML20004D937 (5)

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June 4, 1981

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M Docket No. 50-29 (nr LS05-81 C6-013 p

JUH09193; Mr. James A. Kay J5 ~j Senior Engineer - Licensing Yankee Atomic Electric Company

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\\j 25 Research Drive g.4 Westborough, Massachusetts 01581

SUBJECT:

SEP TOPIC VI-7.8, ESF SWITCH 0VER YANKEE R0WE The enclosed draft safety evaluation report is base.d on the infonration provided by your May 5,1981 letter responses to mvious staff questions.

Our report recomends no changes'ir. planc instrumentation.

You.are requested to review the e1 closed report and to provide us with your corrents, if any, within 30 days of receipt of this letter. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.

Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing

Enclosure:

As stated cc w/ enclosure:

See next page

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June 4, 1981 9

Docket No.'50-29 LS05 06-013 Mr. - James A. ' Kay-Senior Engineer - Licensing Yankee Atomic Electric Company 25 Research Drive Westburough, Massachusetts 01581

SUBJECT:

SEP TOPIC VI-7.B 2SF SWITCH 0VER YANKEE R0WE The enclosed draft safety evaluation report is based on the information provihd by your May 5,1981 letter responses to previous staff questions.

Our report recormends no changes in plant instrumentation.

You are requested to review the enclosed report and to provide us with

-your coments, if any, within 30 days of receipt of this letter.

This topic assessment may.be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.

Sincerely, 1

16fd, 'C Denn s" r

e Operating Reactors Bran No. 5 Division of '.icensing

Enclosure:

As stated cc w/ enclosure:

See next page s

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Mr. J ames A. K ay

• c Mr. James E. Tribble, President Yankee Atomic Electric Corpany 25 Research Drive Westborough, Massachusetts U1581 Greenfield Corrunity College 1 College Drive Greenfield, Massachusetts 01301 Chai rman Board of Selectmen Town of Rowe Rowe, Massachusetts 01367 Energy Facilities Siting Council 14th Floor o

One Ashburton Place Boston, Massachusetta 02108 Director, Criteria and Standards Division Office of Radiation Programs (ANR-460)

U. S. Environmental Protection Agency Washington, D. C.

20460 U. S. Environmental Protection Agency Region 1 Office ATIN: EIS COORDINATOR JFK Federal Building Boston, Massachusetts 02203 Resident inspector Yankee Rowe Nuclear Power Station c/o U.S. NRC Port Office Sox 28 Monroe Bridge, Massachusetts 01350 P00R ORGINA_

YAtlKEE R0WE PLANT SD TOPIC VI-7.B. ESF SITfTCHOVER

. TOPIC VI-7.B:

ESF (ErlGItlEERED SAFETY FEATURES) SWITCH 0VER FROM IflJECTI0tt TO RECIRCULATI0ft f 00E, AUTOMATIC ECCS REALIGt;f!EtlT YAtlKEE R0WE I.

Introduction Most Pressurized tlater Reactors (PWRs) require operator action to realign the ECCS for the recircMion mode folicwing a LOCA. The f!RC staff has been requiring, on a casa-;y-case basis, some automatic features to assist in the realignment of the ECCS from the injection to the recirculation mode of operation. The safety objective of this requirement is to increase the reliability of long-term cooling by reducing the number of operator actions required to change system realignment to the recirculation mode.

The scope of this topic requires a review of the ECCS control system and the operator action required to realign the ECCS from injection to recircula-tion mode following a LOCA. The sequence of events from initiation of the injection mode to completion of the recirculation mode, the systems / components and instrumentation / controls utilized in the injection to recirculation pro-cess, and the automatic and/or manual process required to complete the switch-over process are to be reviewed. The objective of this review is to detennine if automatic switchover is necessary to protect public health and safety.

II.

Review Criteria The current licensing criteria which govern the safety issue are, identified in Table 7-1 of the Standard Review Plan. The most significant of these criteria are:

1.

Branch Technical Position ICSB 20, 2.

IEEE Std 2791971, and 3.

Regulatory Guide 1.62.

III. Related Safety Topics and Interfaces The scope of review for this topic was limited to avoid duplication of effort since some aspects of the review were performed under related topics. The related topics and the subject matter are identified below.

Each of the related topic report contains the acceptance criteria and review guidance for its subject matter.

III-6

- Seismic Design Considerations III-10.A

- Thermal-Overload Protection for Motor Operated Valves III-ll

- Component Integrity i

III-12

- Environmental Qualification IV-1.A

- Operation with Less Than All Reactor Coolant Loops in Service V-10.B

- RHR Reliability V-ll

- High Pressure /I.ow Pressure Interface VI-7.A.3

- ECCS Actuation System i

VI-7.C.1

- Independence of Cnsite Power VI-10.A

- Testing of ESF Systems VI-10.B

- Shared Systems

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VIII-2

- Onsite Emergency Power Systems l

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2-VIII-3

- Emergency de Systems i

VIII-4

- Containment Penetrations The following topics are dependent on the present topic information for completion:

VI-4

- Containment Isolation System VI-7.C.2

- ECCS Single Failure Criterion IV.

Review Guidelines ICSB 20 states that automatic transfer to the recirculation mode is prefer-able to manual transfer and should be provided for standard plant designs submitted for review on a generic basis under the Commission's standardi-zation policy.

ICSB 20 also states that a design that provides manua. f litiation at the system level of the transfer to the recirculation mode, while not ideal, is-sufficient and satisfies the intent of IEEE Std 279 provided that adequate instrumentation and information display are available to the operator so that he can make the correct decision et the correct time. Furthermore, it should be shown that, in case of operator error, there are sufficient time and information available so that the operator can correct the error, and the consequences of such an error are acceptable.

V.

Evaluation Yankee Rowe does not have an automatic transfer and it is not a standard plant submitted for review on a generic basis.

Accordingly, the staff limited its review to the instrumentation and controls that are used to indicate Refueling Water Storage Tank level and to terminate the injection phase of Emergency Core Cooling (ECCS).

The staff's review of ECCS single failures (Topic VI-7.C.2) shows that there are no single failures beyond the failures considered in this topic that could result in the failure of more than one train of ECCS or result in unacceptable offsite doses.

Questions were sent to the licensee in order to obtain sufficient information upon which to conduct an independent review. As a result of the licensee responses the staff determined that the ECCS injection mode is terminated by operator action upon receipt of. a low refueling water storage tank level signal. This signal is derived from a pneumatic level transmitter and a separate electronic level transmitter.

The external reference legs and transmitters for these instruments are electrically heated to prevent-freezing.

The minimum flow lines for the RHR pumps that recirculate the containment water discharge to the storage tank and are closed by operator action as the second step of the changeover from injection to recirculation.

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VI. CONCLUSIONS' The switchover from injection to recirculation in Yankee Rowe is accomp-'

,.:lished. manually-from the control room. The primary instruments for de-

.termining when to make the-switchover satisfy the single failure criterion.

'and are:therefore acceptab1_e.

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