ML20126F618
| ML20126F618 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 12/22/1992 |
| From: | Baker E Office of Nuclear Reactor Regulation |
| To: | Graham P GULF STATES UTILITIES CO. |
| References | |
| TAC-M80315, NUDOCS 9212310023 | |
| Download: ML20126F618 (4) | |
Text
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December ~ 22, 1992 b
Docket-No. 50-458-culf States Utilities
' ATTN:: Mr. Phillip D. Graham Vice President-(RBNG)
Post Office Box 220 St. Francisville, Louisict.c -70775 Doar Mr. Graham:
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SUBJECT:
RIVER BEND STATION, UNIT I - REQUEST FOR ADDITIONAL INFORMATION REGARDING TOPICAL REPORT EA-PT-91-0003-M, SUPPLEMENT 1
" RIVER BEND STATION PLANT-TRANSIENT ANALYSIS METHODOLOGY" (TAC NO. M80315)
The staff is continuing its review of Supplement I of-the topical report,
" River Bend Station Plant Transient Analysis Methodology." The-topical _ report describes the methodology Gulf-States Utilities intends to use for determining _
the operating-limit minimum critical power ratio in the River Bend reload
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licensing analyses. As a result of this review, specific issues and questions have been raised concerning the methods and benchmarking which are included in the attached request for additional information.
You are requested to-provide a prompt response to the enclosure as this will directly impact the overall staff's review schedule.
Please contact us if there are any questions concerning the attached _ request for additional information.
The reporting requirements contained in this letter affect fewer than ten respondents, therefore OMB clearance is not required under Public Law 96-511.
Sincerely, Original Signed By Donna M. Skay for Edward T. Baker, Senior Project Manag'er Project Directorate IV-2 Division of Reactor Projects III/IV/V-Office of Nuclear-Reactor Regulation
Enclosure:
DISTRIBUTION Request for Additional tDocketrFile:
RJones Information NRC PDR-EBaker Local PDR.
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9 Mr. Phillip D. Graham December.22,1992 cc w/ enclosure:
Winston & Strawn Ms. H. Anne Plettinger
-ATIN: Mark J. Wetterhahn, Esq.
3456 Villa Rose Drive 1400 L Street, N.W.
Baton Rouge, Louisiana 70806 Washington, D.C. 20005-3502 Mr. Les England
~ Director - Nuclear Licensing Gulf States Utilities Company St. Francisville, Louisiana 70775 Mr. Philip G. Harris Cajun Electric Power Coop, Inc.
10719 Airline Highway P. O. Box 15540 Baton Rouge, Louisiana 70895 Senior Resident Inspector P. O. Box 1051 St. Francisville, Louisiana 70775 President of West feliciana Police Jury P. O. Box 1921 St. Francisville, Louisiana 70775 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 Mr. -J. E. Booker Manager-Nuclear Industry Relations Gulf Ltates Utilities P. O. Box 2951 Beaumont, Texas 77704 Administrator Louisiana Radiation Protection Division P. O. Box 82135 Baton Rouge, Louisiana 70884-2135 Mr. J. David McNeill, III William G. Davis, Esq.
Department of Justice Attorney General's Office P. O. Box 94095
. Baton Rouge, Louislana 70804-9095
ENCLOSURE
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RE0 VEST FOR ADD [TIONAL INFORMATION RIVER BEND STATIQH PLANT TRANSIENT ANALYSIS HETHODOLOGY' TOPICAL REPORT DOCKET NO. 50-458 1.
Describe the Chapter 9 revision to.the core physics procedures which required the regeneration of the Peach Bottom 2 kinetics data. Why does this change only have a significant effect on the TTI predictions?
2.
Provide the basis for the 95/95 uncertainty values used for the core leakage flow, total core pressure losses, jet pump H-ratio. TCV stroke j
time, initial thermal power, and feedwater maximum runout time.
3.
The Table 6.8 values of 6RCPR,3,,3 and resulting statistical adjustment factors have been determined for specific transients having relatively small values of RCPR. Will the Table 6.8 values of oRCPR o be applied in the RBS licensing analyses on a percent basis,(T,.3e.,
6RCPR/RCPR is assumed constant)? If not, provide justification for the method used to apply these oRCPR,3,,3 uncertainty values.
4.
The scram and doppler reactivity contributions to the excessive reactivity are relatively small initially, but ultimately increase sufficiently to dominate the excess reactivity and terminate the transient. How does the calculated reactivity compare with the reactivity inferred from the Peach Bottom 2 measurements, as a function of time, up to the point of minimum CPR7 Justify the use of the uncertainty in the peak excess reactivity for the scram and doppler reactivity uncertainties.
5.
Compare the GSU and vendor methodologies for determining the flow dependent MCPR limit, and justify any differences. -How do the GSU and vendor predictions of the MCPR, limit compare?
6.
Discuss the difference between the control rod insertion curves for the pressurization and overpressurization events.
7.
Has the RBS model been adjusted to improve agreement with the Peach Bottom 2 measurements and, if so, what is the effect of this adjustment on the inferred peak excess reactivity?
8.
How were the standard deviations of Table 6.8 determined? -Do the RCP%'dEcatedinFigure6.17 values of Table 6.8 include a two-standard deviation a as in 9.
What is the difference between the 4RCPR,3f,3 data of Table 6.8 and Tables 6.a through 6.77
10.
What is causing the ~20% GSU underprediction (relative to the vendor) of the *CPR for the pressure downscale failure (PDR) and feedwater controller failure (FWCF) events? Note that this difference is outside the expected 4CPRnfn given in Table 6.8 for these events, 11.
What initial conditions (e.g., core flow, cycle exposure, power distri-bution, feedwater flow and temperature) will be assumed in the LRNB, PDF, FWCF and MSly closure licensing analyses and are these conditions conservative relative to expected operating conditions?
12.
Will the bypass flow be modelled as a negative fill in the FWCF analysis to ensure there is no overshoot of the bypass flow capacity?
13.
How are calculational uncertainties accounted for in the MSIV closure overpressurization analysis?
14.
Describe the modeling of the closing of the MSIVs and opening of the SRVs in the RBS overpressurization analysis. Does this treatment conservatively bound the performance of these systems?
15.
Provide the predicted peak pressure and margin to limits for each of the reactor coolant pressure boundary components.
16.
In the MSIV closure overpressurization analysis, how many SRVs are considered to be inoperable and is this consistent with the maximum allowed in the technical specifications?
17.
How is the uncertainty in the time-dependent hot-channel radial peaking factor accounted for in the licensing analyses?
18.
What effect does the GSU core physics procedures revision have on the inferred (calculation-to-measurement) peak reactivity differences and the determination of RCPR,3f,37 i
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