ML20003C772
| ML20003C772 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/04/1981 |
| From: | Clark R Office of Nuclear Reactor Regulation |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| MSS-NA1-P, NUDOCS 8103180246 | |
| Download: ML20003C772 (9) | |
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o Mr. William Cavanaugh, III
]A Vice President Generation and Construction Arkansas Power & Light Company 9,\\
P. O. Bor 151 A
Little Rocz, Arkansas 72203 4
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Dear Mr. Cavanaugh:
We have reviewed the report " Qualification of Reactor Physics Methods for Application to Pressurized Water Reactors of the Middle South Utilities System" submitted with your latter dated September 19, 1980. We find that we need the additional information requested in the enclosure in order to complete our review.
We understand that the first application of these physics methocs will not be to the ANO-2 Cycle 2 Spring 1981 startup as discussed in your September 12, 1930 letter. Acco-dingly we do not consider that matters identified in the review of this report necessarily require resolution to su; pert the ANO-2 Cycle 2 startup. We request that you identify a schedule for your response to tre enclosed questions and an identification of your first planned application of this report to ANO-1 and/or ANO-2.
Sincerely,
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Robert A. Clark, Chief Operating Reactors Branch #3 Division of Licensing
Enclosure:
As stated cc: See next page
Arkansas Power ! Licht Conpany CC*
Mr. David C. Tr.!mble Director Criteria and !itandards Division Manager, Licensing Office of Radiation Programr (ANR-450)
Arkansas Powar & Light Cc@any U.S. Environmental Protecti in Agency P. O. Box 551 Washington, D. C.
20460 Little Rock, Arkansas 22203 U.S. Environmental Protec. son Agency M r. Jaces P. O'Hanlon Region VI Office General Manager ATTN: EIS COORDINATOR Arkansas Nuclear One 1201 Elm Street P. 0.* Box 608 First Internati-I,al Building Russellville, Arkansas 12801 Dallas, Texas 75270 Mr. Robert B. Borsua Babcock & Wilcox Nuclear Power Generation Division Suite 420 7735 Old Georgetown Road Director, Bureau of Environmental Bethesda, Maryland 20014 Health Services 4815 West Markham Street Nick Reynolds Little Rock, Arkansas 72201 c/o DeBevoise & Liberman 1200 Seventeenth Street, N.W.
Washington, D. C.
20036 Arkansas Polytechnic College i
Russellville, Arkansas 72801 Honorable Ermd1 Grant Acting County Judge of Pcpe County Pope County Courthouse j
Russellville, Arkansas 72801 Mr. Paul F. Levy, Director Arkansas Department of Energy 3000 Kavanaugh l
Little Rock, Arkansas 72205 i
Mr. Charles B. Brinkman Manager - Washington Nuclear Operations C-E Power Systems 4853 Cordell Avenue, Suite A-1 i
Bethesda, Maryland 20014 i
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FE!: 4 4 1981 REQUEST FOR ADDITIONAL INFORMATION QUALIFICATION OF REACTOR PHYSICS METHODS FOR APPLICATION TO PRESSURIZED WATER REACTORS OF THE MIDDLE SOUTH UTILITIES SYSTEM REPORT NO. MSS-NAl-P (TACS 42982)
Review of the applicant's submittal dated September 19, 1980 on the
" Qualification of Reactor Physics Methods for Application to Pressurized Water Reactors of the Middle South Utilities System" MSS-NAl-P, showed that more information is required in order for us to complete the review.
The subject report deals with the determination of calculational uncer-tainties _and the resultant reliability factors associated with the reactor phy,ics model. There are three PWRs to which this methodology will be yplied.
In particular the cubject report gives an overview of the calculational model and the determinatica of the model uncertainty and reliability.
The model then is applied to reactor operations and to safety evaluations.
Th,e reactor operations includes startup physics tests and power distribu-tion measurements. The safety evaluation includes nuclear heat flux l
and enthalpy rise hot channel factors, rod' worths, shut down margin and reactivity coefficients. The report contains two parts referring respettively to ANO-1 dnit 1 and Unit 2 benchmarking.
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A number of specific questions have been brought forth in the review and the following additional information is required:
1.
IntheexpressionforchSV the total observed uncertainty (p.3-5) the incependence of the calculated uncertainties for rod worth og and the boron coefficient e ht not been established. Note that g
both qucntities are calculated using PDQ-07. Wat is the basis for
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the assumption of R and 7 independence?
3 2.
On p.3-10 and 3-11 it is stated that NAI "perfor:ed an evaluation of the cocparisons of measured and calculated ITC's... The resulting data base..."
Oces this paragraph mean that sece " data condt'.foning" or " data selection" was performed? Give more details on the dau evaluations referred to above.
3.
One Kewaunee cocparison for the isother=al te perature coefficient
(-7.2 pcm/*F) has been deleted and the deletion was justified on the basis that the value is four standard ccyiations from the Kewaunee mean using the pooled estimates of the variance.
(a) fieasurement cannot be rejected en the basis of statistical arguments; (b) at this point the poolability of the data has not been established;-and (c) the value is only abcut two deviaticas from the Kewaunee mean using the Kewaunee estimate of the variance.
=
4
%>t c
. Discuss the suspected measurement error. How would this value affect the reliability factor if it was lef t in the pooled data?
4.
The Isothermal Temperature Coefficient data base listed in Table 3.5(a) includes comparisons froa Kewaunee, Beaver Valley, AND-1 and ANO-2. These plants represent a Westinghouse I-Loop, Westinghouse 3-Loop, B&W, and Coe6ustion plants respective!y.
.,ddress the issue of data poolability in view of the plant design diversity.
5.
The presence of a baron dependent bias in the pooled data for the isothermal temper'ature coefficient appears to indicate that spectral effects are not being fully accounted for by the calculational model or calculational procedures (Section 3.2, P. 3-10). Has this point been investigated before the bias factor was absorbed in the calcu-lational tethodology?
5.
On p. 3-11 using the data of Table 3.5(b) a statistical equivalency test is performed on Kewaunee and ANO-1 data. Given that the ANO-1 has only two entries, comment on the validity of such a statistical l
test.
In view of the lack of. measurements, demonstrate that a 10%
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reliability factor for the Doppler coefficient is conservative I
(Section 3.3, p. 3-16).
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. 8.
Referring to Figures 3.4-3.6 and Table 3.6 on the isotopic comparisons it is not clear whether or not the applicant performed the indicated calculations, hence, demcastrating his capability of using the EPRI-CELL, CiH and the ARMP codes. Did the applicant perform the calculations indicated on Figu ei 3.4-3.67 9.
What adjustments were made to the EPRI-CELL code to mat-h CPM 7 (Section
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3.4, p. 3-17) ?
- 10. Uncertainties in the sp.v.ial nuclide inventory calculation involve un-certainties in the local inventory computation as well as uncertainties in the computation of the spatial burnup distribution (Section 3.4,
- p. 3-17; Section 4.3, p. 4-5).
The uncertainty in the local inventory computation has been dealt with in Section 3.4.
Establish the uncer-tainty in the cocputation of the spatial burnup distribution.
- 11. Uncertainty (b) in the calculation of the spatial nuclide inventory (Section 3.5, pp. 3-22 and 3-24) is only partially addressed in Section 3.4.
What is the value of the uncertainty in the spatial nuclide inventory when the uncertainty in the spatial t
l burnup distribution is accounted for? "
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- 12. What are the one-sided tolerance factors used when relating the uncertainties in s and I to the corresponding reliability factors?
I (Section 3.5, pp. 3-24 and p. 3-25) l l
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. 13. It is stated on p. 3-26 for the power distribution uncertainty as measured by the Rh self powered detectors that 'the signals from these 4
detectors are corrected by the on-site process computer... ?hese corrected signals, or reaction rates..."
(a) Usually the process computer will process the Rh detec'or signals' in a manner which will account for detector sensitf rity, depleticis,
. leakage etc.
(b) The process computer will determine a quantity which represents the reaction rate.
In view of the above comments, explain whether further corrections to the Rh signals have been applied ard what corrections were they?
- 14. The reaction rate to power density conversion factors are calculated for each assembly as a function of exposure using a 20 pDQ model.
In view of the discussion of power distributfor reliability factors presented in Section 3.7, p. 3-109, how are axial effects for these factors accounted for?
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- 15. Axial newer shapes are shown at locations DIO, B8, and R4 (Figures 3.12 l
l through 3.38). Explain why no distributions are show'n for central or l
near central locations. Show some axial power shapes of central l
locations and describe the normalization to plant measurements and l
PDQ.
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- 16. On page 3-32 it appears that "the simulation errors" are due to (a) input errors and sc) approximations in the representation of a given state point. Describe in detail the errars implied by the term " simulation error".
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- 17. How are errors associated with asymmetries (e.g. asymmetric fuel ournup distributions) accounted for in the model uncertainty analysis and in the core monitoring system uncertainties?
(p. 3-34)
- 18. In view of the systematic pattern of errors shown in Tables 3-10, 3-11, and 3-12, how is detector intercaifbration maintained? Is there a cycle or exposure dependent method used in correcting possible drifts
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away from intercalibration, and if so, please describe it.
- 19. It is stated on p. 3-37 and 3-38 that hardware problems in Cycle 1 led to the elimination of Cycle ! dats from inclusion in estimating an axial level dependent mean difference for ANO-1 (Table 3-18, Figure 3.40, p. 3-85, 86). This suggests that there should be a large uncer-tainty in the bias. With respect to the dsta included in Table 18, on what basis is it concluded that the differences between Cycle 1, Cycle 2, and Cycle 3 art due to hardware problems and how is it insured that they are specific only to Cycle 1?
- 20. What is the mechanism or phenomena responsible for the axially varying reliability factoe (RF)? Why does ANO-1 require an axially varying RF, while ANO-2 does not?
Is the axial variation cycle dependent?
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- 21. Discuss the effects caused by the nodal code albedo selection, calibra-tion errors and crud buildup on the axial dependence of the reliability factor.
(
. ??. With regard to the pooling of statistics, it: discu;sion on the applica-tion of the Barleti Test is not clear in the light of F:sures 3440 and 3.41.
Discuss the basis for pcoling the statistics in Tables 3-13 to 3-17 in view of the fact that the data failed the Barlett Test.
Supply curves similar to Figure 3.41, separately for cycles 1, 2, and 3.
- 23. The large differences in the statistics between Cycle 1 on one hand and Cycle 5 and 3 on the other suggest that they are being drawn from different porelations. Justify, therefore, the use of a one-sided tolerance factor corresponding to over 1300 data points of 1.71 (p 3-110).
- 24. In the equation on page 4-4, what one-sided tolerance factor will be used with the uncertainty fraction? Does the (ANO-2) 2.2t uncertainty fraction include the uncertainties resulting frca the extrapolation to unnonitored locations and other Process Computer approximations not accounted for in the codel error? What is the uncertainty factor to be used in Fg?
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