ML16152A754

Discusses NRC Response to B&W Owners Group on ATWS Issue. Licensee Requested to Submit plant-specific Conceptual Design for Option Selected Among Three Options Considered in Encl NRC Ltr

ML16152A754
Person / Time
Site:	Oconee
Issue date:	11/22/1988
From:	Pastis H Office of Nuclear Reactor Regulation
To:	Tucker H DUKE POWER CO.
References
TAC-59119, TAC-59120, TAC-59121, NUDOCS 8811280196
Download: ML16152A754 (7)

Text

+ 4UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 November 22, 1988 Docket Nos.:

50-269, 50-270 and 50-287 Mr. H. B. Tucker, Vice President Nuclear Production Department Duke Power Company 422 South Church Street Charlotte, North Carolina 28242

SUBJECT:

NRC RESPONSE TO THE BABCOCK AND WILCOX OWNERS GROUP ON ATWS (TACS 59119, 59120, AND 59121)

Re:

Oconee Nuclear Station, Units 1, 2, and 3 As you are aware, a meeting was held on August 17, 1988 between representatives of the Babcock and Wilcox Owners' Group (BWOG) and the NRC regarding the NRC staff's position on the various issues covered in the staff's generic B&W safety evaluation (SE) regarding the ATWS issue (10 CFR 50.62). The main-point of disagreement was the issue of power supply independence. In this meeting, the staff presented three options on this matter which it considered acceptable.

These three approaches have been formally documented in the letter sent to the Chairman of the BWOG ATWS Committee dated September 7, 1988, a copy of which is attached.

In summary, we stated in our letter to Mr. Stalter our preference for adoption of the first option. However, you may wish to consider each of the three options outlined in the enclosed letter in responding to our generic B&W ATWS SE.

You should promptly submit your plant specific conceptual design for the option you have selected. The NRC will review your conceptual design package within 30 days and provide you with an approval or disapproval with comments.

Since the generic design review has been completed and the options acceptable to the staff for resolving the ATWS power supply issue are sufficiently clear, it is our position that our safety evaluation of your plant-specific submittal does not have to precede your implementation of the required ATWS equipment.

Accordingly, your plant should install, upon receipt of our approval of your conceptual ATWS design, the required ATWS equipment during its next refueling 88112q0196 88-1-12-2 PDR ADOCK 05C)0o269 P

PDC

Mr. H.

November 22, 1988 outage. If this cannot be accomplished, submit your proposed implementation schedule, including justification in accordance with 10 CFR 50.62(d), for our review and approval.

If you have any questions on this matter, please contact me at (301) 492-1497.

Sincerely, Helen N. Pastis, Project Manager Project Directorate 11-3 Division of Reactor Projects -

I/II Office of Nuclear Reactor Regulation

Enclosure:

As stated cc: See next page

Mr. H.

November 22, 1988 outage. If this cannot be accomplished, submit your proposed implementation schedule, including justification in accordance with 10 CFR 50.62(d), for our review and approval.

If you have any question on this matter, please contact me at (301) 492-1497.

Sincerely, Helen N. Pastis, Project Manager Project Directorate 11-3 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosure:

As stated cc: See next page DISTRIBUTION:

NRC PDR Local PDR PDII-3 Reading S. Varga 14-E-4 G. Lainas 14-H-3 D. Matthews 14-H-25 M. Rood 14-H-25 H. Pastis 14-H-25 OGC 15-B-18 E. Jordan MNBB-3302 B. Grimes 9-A-2 D. Lynch 13-E-21 ACRS (10)

P-315 PD P DI\\t PU//

HP is:sw DMatthews 1/ 1A/88

/ 2/88

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Mr. H. B. Tucker Oconee Nuclear Station Duke Power Company Units Nos. 1, 2 and 3 cc:

Mr. A. V. Carr, Esq.

Mr. Paul Guill Duke Power Company Duke Power Company P. 0. Box 33189 Post Office Box 33189 422 South Church Street 422 South Church Street Charlotte, North Carolina 28242 Charlotte, North Carolina 28242 J. Michael McGarry, III, Esq.

Bishop, Liberman, Cook, Purcell & Reynolds 1200 Seventeenth Street, N.W.

Washington, D.C. 20036 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 525 1700 Rockville Pike Rockville, Maryland 20852 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 Senior Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 Office of Intergovernmental Relations 116 West Jones Street Raleigh, North Carolina 27603 Honorable James M. Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621

Enclosure September 7, 1988 Mr. L. C. Stalter Chairman BWOG/ATWS Committee Davis Besse Nuclear Power Station 5501 North S. R. 2 (Mail Stop 3205)

Oak Harbor, Ohio 43449

SUBJECT:

AUGUST 17, 1988 B&W/NRC ATWS MEETING The purpose of this letter is to summarize major points addressed during the meeting which was held with the B&W ATWS owners group on August 17, 1988 to' discuss the overall ATWS Rule requirements including power supply independence as related to the staff generic B&W ATWS SER.

After a presentation by you and other members of the owners group, the staff provided clarification on various acceptable design options that would resolve the power supply independence issue. We concluded that each licensee should consider each option as it applies at each specific plant. The following options were presented by the staff:

1. Provide a DSS/AMSAC design as depicted in the viewgraph (Figure 1) presented at the meeting. This viewgraph shows the DSS/AMSAC being powered via a 480 volt bus with its own independent (i.e., not associated with the RTS) non-Class IE batter rec ifier and charger that provide 120 VAC to the ATWS circuitry.

2. Provide a power source to the DSS as discussed above but non-battery backed. In addition, provide a discussion showing that for all loss of offsite power scenarios, the rods will be released through a loss of voltage to the 480 VAC holding mechanism. Furthermore, show that the Emergency Feedwater Initiation and Control System (EFIC) design (or its equivalent) meets the requirements of the ATWS Rule (i.e.,

show that EFIC and AMSAC are equivalent in that they both perform the same function). If EFIC is powered through RTS 120 VAC buses then show by a failure modes and effects analysis that common mode failures will not propagate through the power supplies and disable both EFIC and the RTS. For this case, the EFIC system has to be a Class 1E system.

3. Provide a Class 1E DSS that is powered by RTS power sources and show through a failure modes and effects analysis that common mode failures will not propagate through the power supplies and disable both DSS and the RTS. EFIC is to be treated as discussed in (2) above.

L. C. Stalter

-2 Based on our discussions to date, it is apparent that the power supply issue has delayed the implementation of the ATWS system at the B&W plants. We are concerned over this delay and strongly recommend that the B&W licensees proceed with their planned ATWS implementation utilizing the option that will support the quickest resolution of the power supply independence issue. Option 1 will provide the most expeditious resolution and would clearly meet the power supply independence guidance published with the ATWS Rule. The approaches specified in options 2 and 3 are significantly more complex In that they involve the development of specific detailed failure modes and effects analyses. Such approaches could significantly delay resolution of the power supply independence issue (separation issue) and may ultimately lead to non-acceptance by the staff should unacceptable failure modes be identified.

Following receipt of each plant specific "conceptual" design package, the staff plans to review the package within 30 days and to approve, or disapprove with comments, the proposed design. This will be followed by the issuance of a safety evaluation upon receipt of a more detailed design package. Since the generic design review has now been completed and the options for resolving the power supply issue are sufficiently clear, we have concluded that the staff safety evaluation does not have to precede the implementation of the required ATWS equipment. In other words, our safety evaluation would be a "post-imple mentation" review. All B&W plants, upon receipt of the NRC approval of the conceptual design, should install the ATWS equipment during their next refueling outage. In special cases where this can't be accomplished, it should be brought to the attention of the staff for their review and approval per 10 CFR 50.62(d).

Sincerely, Gary Holahan, Acting Director Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation

Enclosures:

As stated

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