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MAY 11985
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MEMORANDUM FOR:
T. M. Novak, Assistant Director for Licensing, DL FROM:
L. S. Rubenstein, Assistant Director for Core and Plant Systems, DSI
SUBJECT:
SAFETY EVALUATION REPORT SUPPLEMENT FOR DIABLO CANYON UNIT 2 Plant Name:
Diablo Canyon Unit 2 Docket Numbers:
50-323 Licensing Stage:
0L Responsible Branch:
Licensing Branch #3 Project Manager:
H. Schierling DSI Review Branch:
Core Performance Branch Review Status:
Complete The Core Performance Branch has prepared the attached supplement to the Diablo Canyon Unit 2 SER regarding Section 4.4, " Thermal-Hydraulic Design". This supplement closes the issue of fuel rod bowing penalty on DNBR. This SER was requested by Carl Schulten of DL on April 22, 1985 to confirm our approval of a change made to the Diablo Canyon 2 Technical Specifications to bring them up to date with the current Westinghouse methods for analyzing fuel rod bowing.
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R. Bernero H. Thompson G. Knighton H. Schierling C. Schulten
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SAFETY EVALUATION REPORT SUPPLEMENT FOR DIABLO CANYON UNIT 2 4.4 Thermal Hydraulic Designs Effect of Fuel Rod Bowing on DNB:
In Diablo Canyon SER Supplement #6, the staff stated that as an interim measure, we will include a burnup dependent penalty factor to be applied to the reactor operating limits in Section 3.2.3 of the Technical Specifications to reflect the reduced DNB conditions caused by increasing fuel rod bowing.
Subsequent to issuance of the SER Supplement, the Westinghouse topical report WCAP-3691, Revision 1, " Fuel Rod Bow Evaluation", has been approved by the staff. This rod bow penalty evaluation method applies statistical convolution of the critical heat flux test data and inter-fuel rod gap closure data to derive the rod bow penalty on DNBR. The use of this method results in a significantly lower red bow penalty compared to the interim method previously used. The applicant has submitted a table of rod bow penalty as a function of fuel burnup calculated with the approved Westinghouse method.
Since rod bow and gap closure increase with fuel burnup, the rod bow penalty on DNBR increases with burnup. However, even though the plant may be operated at higher burnup, the maximum fuel burnup used for the rod bow penalty calculation is 33,000 MWD /MTU. The reason for using 33,000 MWD /MTU as a cutoff point is because the physical burndown effect of the high peaking fuel rod will exceed the rod bow effects at higher burnup.
By the time the fuel exceeds a burnup of 33,000 MWD /MTU, it is not capable of achieving limiting peaking factors due to the decrease in fissionable isotopes and the buildup.of fission product inventory.
Therefore, the rod bow penalty value of less than 3% DNBR at 33,000 MWD /MTU represents the maximum rod bow penalty for Diablo Canyon plants having 17x17 R-Grid fuel assemblies.
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d 9-2 However, credit is available to offset this rod bow CNBR penalty. The generic margin (credit) totaling 9.1 percent DNBR is derived from the difference between the design and required values on the following items:
(a) design DNBR limit, (b) grid spacing multiplier, (c) thermal diffusion coefficient, (d) DNBR spacer factor r.ultiplier and (e) 8 pitch reduction. Since the rod bow penalty is completely compensated by the available margin of 9.1 percent, no penalty is required in the reactor operating limit. We have incorporated this rod bow penalty compensation in the Bases of the Diablo Canyon Technical Specifications.
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UNITED STATES NUCLEAR REGULATORY COMMISSION i
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Docket Nos.: 50-275 and 50-323
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MEMORANDUM FOR: Chairman Palladir.o Connissioner Roberts Commissioner Asselstine Commissioner Bernthal Commissioner Zech I
FROM:
Hugh L. Thompson, Jr., Director
$tt bf Division of Licensing Y
Office of Nuclear Reactor Regulation h
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SUBJECT:
DIABLO CANYON - SSER 31: STAFF EVALUATION OF MISCELLANE0US MATTERS FOR UNIT 2 (80ARD NOTIFICATION N0.85-051 )
In accordance with NRC procedures for 8 ard Notifications the enclosed Supplement No. 31 to the Diablo Canyon Safety Evaluation Report (SSER 31), dated April 1985, is provided for your information. SSER'.31 pre:ents the staff evaluation of j
those matters that needed to.be appropriately resolved prior to a licensing decision. SSER 31 includes the basis for certain license conditions that are included in the Unit 2 low power operating license. The report also includes the staff evaluation of certain NUREG-0737 Items. While the report was specifically prepared in support of a Unit 2 licensing decision it also addresses matters with respect to Unit 1, as.. pplicable.
The staff briefed the Commission on these.mtterstin a meeting on April 23, 1985.
There are no issues identified in the repoet that need further evaluation prior to low pow'er operation of Diablo Canyon Unit 2.
By copy of this memorandum the Appeal Board and the parties to the Diablo Canyon proceeding are provided the same information.
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,f Hugh L.
omps n, r., Director gY Division of Licensing Office nf Nuclear Reactor Regulation
Enclosure:
As stated cc:
T. S. Moore, ASLAB T
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W. R. Johnson, ASLAB 3
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Parties to the Proceeding
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FOR THC Di$1 AICT of COLUWe:4 Cahaulf p
5I September Term,1984 No. s4iuo U;dttd ggg San 1,uls Obispo Mothers for Pasca, DM0fCblabioCith N@ NAY I 1985 United States Nuclear Regulatory Qggggg4y18HER Conrnission And the Un1ted States or America
~And Consolidated Cases, i
Robinson, Cisluf Judge; Wright, Tamm. Wald, Mikva, Edwards, Ginsburg, Bork, soalla and $ tare, ctreult BEFOREn i
Judges SEEEE Upon consideration of petitioners' motion for leave to file the exhibits in support of the suggestion for rehearl'ng en bane, thereto, and of the suggestion for rehearing g b,a,no, 1
l responses it is the motion for leave to ORDERED, by the Court en bane, that l
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file exhibits is granted, and it 4.
that petitioners' PURTHER ORDERED, by the Court en* bane, is is granted in part, and it suggestion for rehearing en bane FIEfl1RR ORDERED, by the Cour t en banc, that only Section III.B of the Court's opinion, and the corresponding part of the judgment of the Court. Issued on December 3), 1984, are hereb vacated, and it is
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4 September Term,19u No. 34-i4:e that the full power FURT)F.R ORDERED, by the Court en bene, stayed pending.the operating ficense remains in effect and is not rehearing en bane.
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FOR THE COURT GEORGE A. PISHER, CLERK I
BY Robert A. Bonner Chief Deputy Clerk i
.i for leave to ffle Circuit Judge Berk would.dhny Lise neutlenexhibits in supp ld deny the suggestion
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.iteetez e,,,,1 re,so Muitch States Court of AppenIn F091Ms DigikiCT or COLuwaia cim Ulf No. s4-m e Septembc/ Term,199 5n uls Obispo Mothers for Penea,
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l United States Nuclear Regulatory GEORGE A. FISHER Conynission And the United States of y
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1 Wald and Bork, Circuit Judges, and Wilkey, Senior 4
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Circuit Judge j
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Upon consideration of petitioners' petition for it is ORDF. RED by the Court, that the petition for rehearing is denied.
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FOR TIE COURT GEORGE A. FISHER, CLERK BY:
N Robert A. Bonner Chief Deputy Clerk Senior Clrcuit Judge Wilkey did not participate in this order.
Circuit Judge Wald would grant the pe'titlon for rehearing.
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IN RESPONSE, PLEASE REFER TO:
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NUCLEAR REGULATORY COMMISSION f
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GCunningham Taylor MEMORANDL'M FOR:
WJlliam J. Dircks, Executive Director for Operation
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FROM:
Samuel J. Chilk ecretary
SUBJECT:
STAFF REQUIREMENTS - DISCUSSION /POSSIBLE VOTE ON DIABLO CANYON-2 LOW POWER LICENSE, 2:30 P.M., TUESDAY, APRIL 23, 1985, COMMISSIONERS' CONFERENCE ROOM, D.C. OFFICE (OPEN TO PUBLIC ATTENDANCE)
The Commission met to discuss and decide whether a fuel load and low power license should be issued for Diablo Canyon-2.
The Commission voted 4-1 (Commissioner Asselstine disapproving) to issue an order authorizing the Director of Nuclear Reactor Regulation (NRR) to issue a license permitting fuel loading and low power testing at Diablo Canyon Unit 2.
(Subsequently, the Assistant Se'cretary signed an order author-izing the Director of NRR to issue a license permitting fuel loading and low-power testing of this plant.)
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Chairman Palladino Commissioner Roberts Commissioner Asselstine Commissioner Bernthal Commissioner Zech Commission Staff Offices PDR - Advance DCS - 016 Phillips Rn'd Off. EDO Date...b..b:.f.>,. %
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