ML20136D703

Memorandum Setting Forth Reasons for Ruling Denying Util 850920 Motion for Summary Disposition of Joint Intervenors Contention (D) & Identifying Concerns to Be Addressed During Evidentiary Hearing.Served on 851119

ML20136D703
Person / Time
Site:	Turkey Point
Issue date:	11/18/1985
From:	Lazo R Atomic Safety and Licensing Board Panel
To:
References
CON-#485-245 84-496-03-LA, 84-496-3-LA, OLA, NUDOCS 8511210348
Download: ML20136D703 (6)

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$c,D NUCLEAR REGULATORY COMMISSION p ATOMIC SAFETY AND LICENSING BOARD [ . p Before Administrative Judges: '${'f

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Dr. Robert M. Lazo, Chairman Dr. Richard F. Cole Dr. Emmeth A. Luebke SWLu NOV 191985 In the Matter of Docket Nos. 50-250-OLA-1

) 50-251-0LA-1 FLORIDA POWER & LIGHT COMPANY ASLBP No. 84-496-03 LA (Turkey Point Plant, (Vessel Flux Reduction)

Units 3 & 4)

November 18, 1985 MEMORANDUM By unpublished order dated November 8,1985, this Licensing Board denied Licensee Florida Power and Light Company's September 20, 1985 motion for sumary disposition of Intervenors' (Center for Nuclear Responsibility, Inc., and Joette Lorion) contention (d). NRC Staff supported Licensee's motion. Intervenors opposed the motion in responses of October 25 and November 7, 1985. This Memorandum sets forth the reasons for our ruling and identifies some concerns which need to be addressed in an evidentiary hearing.

Contention (d) was limited in scope by the Board's ruling on a prior motion for sumary disposition. That ruling of August 16, 1985, while denying Licensee's motion, did at p. 54 limit the scope of the 8511210348 851118 PDR ADOCK 05000250 356L

2 litigation to the following three issues:

1. Whether the DNBR of 1.17 which the amendments impose on the 0FA fuel in Units 3 and 4 compensates for the three uncertainties outlined by the Staff in its December 23, 1983 SER on the amendments, at 4.

2. Whether, if the DNBR of 1.17 does not compensate for those uncertainties, the SRP's 95/95 standard, or a comparable one, is somehow satisfied.

3. Whether, if that standard is not being satisfied, the reduction in the margin of safety has been significant.

The Licensee has the burden of showing in hearing either that the application of a DNBR of 1.17 to the 0FA fuel in Units 3 and 4 satisfies the 95/95 standard, or that if such application does not, the reduction in the margin of safet (BoardOrder of 8/16/85 at 54.) y is not significant.

Licensee's motion of September 20, 1985 addresses each of the above three issues.

In response to the first issue, both Licensee and Staff state that the design limit DNBR of 1.17 does not include any of the uncertainties associated with rod bow, hydraulics of the transitional mixed core or uncertainties related to application of the WRB-1 correlation to the 15x15 0FA fuel design. Licensee states that such uncertainties are considered in the analysis of anticipated operational occurrences with the results then compared to the 1.17 DNBR limit to determine acceptability. Dzenis, at 2. Staff appears to agree, stating that the uncertainties associated with rod bow, mixed core hydraulic and application of the WRB-1 correlation were accounted for in Licensee's

" predictive analysis used to calculate minimum DNBR by assuring that the J

3 calculated minimum DNBR of 1.34, when penalized or reduced by 10.5 percent for ta: three uncertainties, was greater than the DNBR fuel design limit t.f 1.17. Yi-Hsiung Hsii, at 6-8.

In its response, the Staff describes two approaches to account for uncertainties. The Licensee may increase the DNBR acceptable fuel design limit by an amount equal to the penalty for the uncertainties or the minimum DNBR calculated by predictive computer analysis may be reduced or penalized by an amount equal to the uncertainty penalty. In either case, the calculated minimum DNBR (in this case, reported to be 1.34), even if penalized for all uncertainties as in the latter method, must exceed the DNBR specified acceptable design limit. Id., at 5-6.

Intervenor argues that Licensee admits that uncertainties are not included in the DNBR limit of 1.17 and both the WRB-1 correlation and Licensee's own plant specific safety analysis have been predicated on the assumption of a homogenous core rather than a mixed core.

Accordingly, the applicability of a DNBR of 1.17 to the 0FA fuel in the transitional mixed core is highly questionable because it is based on a extrapolation of results obtained from a consideration of homogenous cores only. Intervenors further argue that in the absence of any detailed studies of the transitional mixed core, numerical penalties are little more than educated guesses. A question is also raised as to the possibility of non-linear interactions in the transitional core.

Intervenors pose the possibility that the three uncertainties are not independent but interact with one another, using as an example, the likelihood that the rod bow phenomenon might interact in a fairly

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complicated way with the "already complicated non-uniform hydraulic resistance phenomenon" in the transition core. Edwards, at 2-5.

Intervenors opine that neither Licensee nor Staff have proven that the 1.17 limit after compensating for the uncertainties will meet the 95/95 standard. Lorion, at 2-3.

In response to the second question, Licensee and Staff state that the Standard Review Plan's 95/95 confidence level standard is satisfied by assuring the minimum DNBR values calculated for all normal and anticipated operational occurrences after accounting for uncertainties are greater than the 1.17 DNBR acceptance limit. Dzenis, at 2-3; Yi-Hsiung Hsii, at 7-8. Licensee argues that the application of uncertainties to results obtained from predictive analysis, rather than design basis limits, is common in the engineering field further indicating that approach has been used for all Westinghouse safety analyses for Turkey Point, (underlined in original) independent of fuel design or critical heat flux correlation. Dzenis, at 3. Intervenors argue that the 1.17 DNBR design limit constitutes the 95/95 bounding

, value for experimental data and if the value of 1.17 does not compensate for uncertainties, it follows that a 1.17 design limit DNBR, which may someday be used for the calculated DNBR, does not provide the 95%

confidence prescribed in the Standard Review Plan, NUREG-0800, Section 4.4. Lorion, at 3.

As to the third item, Licensee states that the standard is being satisfied. Dzenis, at 4. Staff agrees, stating that the "DNBR of 1.17 meets SRP's 95/95 standard and a 1.34 calculated minimum DNBR is more conservative (even if penalized for uncertainties)." Staff further

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states that there has been no significant reduction in safety margin, and no reduction below the minimum safety margin provided by the 95/95 standard. Yi-Hsiung Hsii, at 8. Intervenors argue that, if compensation for uncertainties in the 1.17 DNBR design limit causes it to fail to meet the 95/95 standard, then the amendments in question will i

cause a significant reduction in the margin of safety for the Turkey Point reactors. Lorion, at 4-6.

The Board has carefully reviewed the filings in accordance with the standard of review necessary for motions of this type and finds that while Intervenors might not necessarily prevail on the merits, sufficient doubt has been raised as to the appropriateness of certain procedures used and the uncertainties included in the establishment of a limiting DNBR for Turkey Point Units 3 and 4. Because of these doubts, the movant has not demonstrated that there is no genuine issue as to any material fact and that it is entitled to a decision as a matter of law.

Accordingly, Licensee's motion must be denied. While these doubts are principally articulated in Intervenors' response, the following are some of the Board's concerns for consideration in preparation for hearing:

o What if any uncertainties are included in the ascertainment of the DNBR value of 1.17? 1.e. rod bow, hydraulic flow pattern considerations, ideal conditions, etc.

l o Meaning of the term " design" DNBR or "DNBR limit" and i how it is applied to the Turkey Point plant. How is l the " calculated minimum" DNBR related to this and how is it used at Turkey Point?

l o Procedures and/or techniques used to ascertain the

! " calculated minimum" DNBR including any assumptions and uncertainties and how they might affect the validity of I

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the calculation. How much confidence should we have in this calculated value?

o Concerning the three uncertainties listed, what are the bases for the estimates and how much confidence can we place on the estimates? Of particular interest are the penalty values discussed in the NRC Safety Evaluation related to Amendment 99 at pages 3 and 4.

o Is the approach used for all Westinghouse Safety analyses at Turkey Point, (Dzenis, at 3) unique to Turkey Point?

FOR THE ATOMIC SAFETY AND LICENSING BOARD

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Robert M. Lazo, Chairman ADMINISTRATIVE JUDGE Dated at Bethesda, Maryland, this 18th day of November, 1985.

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