ML17306A538

Provides Diverse Auxiliary Feedwater Actuation Sys Design Changes & NRC Comments,Per & 920117 Conference Call.Nrc Finds Clarification Acceptable Since Design Will Meet Regulatory Requirement

ML17306A538
Person / Time
Site:	Palo Verde
Issue date:	03/03/1992
From:	Trammell C Office of Nuclear Reactor Regulation
To:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
References
TAC-M59124, TAC-M62798, TAC-M67168, NUDOCS 9203120358
Download: ML17306A538 (7)

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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 March 3, 1992 Docket Nos.

50-528, 50-529 and 50-530 Hr. William F.

Conway Executive Vice President, Nuclear Arizona Public Service Company P.O.

Box 53999

Phoenix, Arizona 85072-3999

SUBJECT:

REVIEW OF PALO VERDE DAFAS DESIGN CLARIFICATION (TAC NOS.

H59124, H62798, and H67168)

By letter dated November 8, 1991, Arizona Public Service Company (APS) provided a number of clarifications which identified some changes to the diverse auxiliary feedwater actuation system (DAFAS) design from the conceptual design which was approved by NRC on October 18,

1990, and July 4, 1991

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A conference call was held on January 17,

1992, between the staff and the licensee to discuss these clarifications.

The following are the DAFAS design changes and the staff's comments:

APS clarification refers to NRC letter dated July 4,

1991, page 2,

Item (3).

The staff comment stated that DAFAS uses narrow range steam generator level sensors.

APS stated that the DAFAS uses wide range steam generator level sensors.

Staff Comment:

The enclosure to the APS letter dated July 31, 1990, states that the DAFAS uses narrow range safety channel level sensor inputs.

The APS letter dated November 8, 1991, states that the narrow range level instruments do not have sufficient measurement range for the analyzed low steam generator level events.

The Palo Verde DAFAS design uses wide range steam generator level sensors.

There are four narrow range channels and four wide range channels for each steam generator.

The narrow range channels are used for high level trip, and the wide range channels are used for low level trip and auxiliary feedwater actuation.

The wide range level instruments are acceptable because the signals from sensor output to the final actuation device for the DAFAS are diverse from the reactor trip system (RTS).

Although the sensors are shared between the DAFAS and the RTS, this is allowed in the ATWS rule.

The staff finds this clarification acceptable.

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Mr. Wi1 liam F.

Conway 2.

APS clarification refers to NRC letter dated July 4,

1991, page 2,

Item (3).

The staff comment stated that the level signal source is a Foxboro level transmitter.

APS stated that the level transmitter is currently manufactured by ITT Barton.

Staff Comment:

In Attachment D of the Palo Verde DAFAS design change

package, the APS provided the Foxboro current-to-voltage converter instrument data sheets for staff information which led staff to believe that the Palo Verde DAFAS uses the Foxboro level transmitters.

The staff finds this clarification acceptable.

3.

APS clarification refers to NRC letter dated July 4,

1991, page 2,

Item (3)

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The staff comment stated that each programmable logic controller (PLC) will initiate an actuation signal.

APS stated that each PLC will generate a half-leg trip actuation signal in each Auxiliary Relay Cabinet (ARC) and that two PLC actuations in an ARC are required for a full auxiliary feedwater system actuation.

Staff Comment:

The staff finds this clarification acceptable since the design will meet the regulatory requirement.

4, APS clarification refers to NRC letter dated October 18,

1990, page 9, Section 4.3., third item, which stated that the DAFAS will stop AFW flow to the affected steam generator after reaching a

predetermined level setpoint (about 30 minutes after actuation) at which time manual operator intervention will control the system.

APS stated that the final design for the DAFAS reset action has been modified to be an automatic reset.

The automatic reset provides improved integrated system performance, including predictable steam generator cooldown rates during and after an ATWS event.

Staff Comment:

The staff finds this clarification acceptable.

Hr. William F.

Conway Based on the information provided by the licensee and the discussion on January 17, 1992, the staff concludes that the clarifications provided in the November 8, 1991, letter are acceptable.

These clarifications do not change the overall conclusion in the staff's safety evaluation dated October 18,

1990, which stated that the DAFAS proposed for implementation at the Palo Verde Nuclear Generating Station, Units 1, 2,

and 3, conforms to the requirements of 10 CFR 50.62 and is, therefore, acceptable.

Sincerely, Charles H. Trammell, Sr. Project Hanager Project Directorate V

Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation CC:

See next page

Hr. William F.

Conway Arizona Public Service Company Palo Verde CC:

Nancy C. Loftin, Esq.

Corporate Secretary

& Counsel Arizona Public Service Company P.

O.

Box 53999, Hail Station 9068 Phoenix, Arizona 85072-3999 Jack R.

Newman, Esq.

Newman

& Holtzinger, P.C.

1615 L Street, N.W., Suite 1000 Washington, D.CD 20036 James A. Beoletto, Esq.

Southern California Edison Company P.

O.

Box 800

Rosemead, California 91770 Senior Resident Inspector U.S. Nuclear Regulatory Commission HC-03 Box 293-NR Buckeye, Arizona 85326 Regional Administrator, Region V

U. S. Nuclear Regulatory Commission 1450 Maria Lane Suite 210 Walnut Creek, California 94596 Ignacio R. Troncoso Senior Vice President El Paso Electric Company Post Office Box 982 El Paso, Texas 79960 Roy P.

Lessey, Jr.,

Esq.

Bradley W. Jones, Esq.

Arkin, Gump, Strauss, Haver and Feld El Paso Electric Company 1333 New Hampshire Ave., Suite 400 Washington, D.C.

20036 Hr. Charles B. Brinkman, Manager Washington Nuclear Operations, ABB Combustion Engineering Nuclear Power 12300 Twinbrook Parkway, Suite 330 Rockvi lie, Maryland 20852 Mr. William A. Wright, Acting Director Arizona Radiation Regulatory Agency 4814 South 40 Street

Phoenix, Arizona 85040 Chairman Haricopa County Board of Supervisors 111 South Third Avenue

Phoenix, Arizona 85003

(*

Mr. William F.

Conway Based on the information provided by the licensee and the discussion on January 17, 1992, the staff concludes 'that the clarifications provided in the November 8, 1991, letter are acceptable.

These clarifications do not change the overall conclusion in the staff's safety evaluation dated October 18, 1990, which stated that the DAFAS proposed for implementation at the Palo Verde Nuclear Generating Station, Units 1, 2, and 3, conforms to the requirements of 10 CFR 50.62 and is, therefore, acceptable.

Sincerely, Originai signed by Charles M. Trammel 1, Sr. Project Manager Project Directorate V

Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation CC:

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