ML20216B772
| ML20216B772 | |
| Person / Time | |
|---|---|
| Issue date: | 05/12/1998 |
| From: | Joshua Wilson NRC (Affiliation Not Assigned) |
| To: | Reda R GENERAL ELECTRIC CO. |
| References | |
| TAC-M97490, TAC-M99069, NUDOCS 9805180429 | |
| Download: ML20216B772 (6) | |
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UNITED STATES j
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.n May 12, 1998 Mr. Ralph J. Reda, Manager Fuel and Facility Licensing GE Nuclear Energy P. O. Box 780, MC J26 3901 Castle Hayne Road Wilmington, NC 28402
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR GE TOPICAL REPORTS NEDC-32601P (TAC NO. M97490) AND NEDC-32694P (TAC NO. M99069)
REFERENCES:
1.
G. A. Watford (GE) to Document Control Desk (NRC), Responses to Request for AdditionalInformation for GE TopicalReport, NEDC-32601P,
" Methodology and Uncertainties for Safety Limit MCPR Evaluations",
January 8,1998, 2.
G. A Watford (GE) to Document Control Desk (NRC), Responses to Request for AdditionalInformation for GE Topical Report, NEDC-32694P,
" Power Distribution Uncertainties for Safety Limit MCPR Evaluations",
January 9,1998.
Dear Mr. Reda:
Tne staff is reviewing your submittals, referenced above and dated January 9 and 10,1998, responding to the staff's August 20,1997 request for additionalinformation (RAI), regarding the methodology and uncertainties for safety limit MCPR evaluation and the power distribution uncertainties for safety limit MCPR evaluation. The staff concludes that additionalinformation is needed before it can complete its review. Enclosure 1 contains an RAl related to the staff's review of NEDC-32601P, " Methodology and Uncertainties for Safety limit MCPR Evaluations,"
and NEDC-32694P, " Power Distribution Uncertainties for Safety Limit MCPR Evaluations."
These questions were previously provided to you in a technicalinformation exchange meetin with the staff held on March 17,1998, at NRC headquarters in Rockville, Maryland.
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-2 May 12, 1998 You are requested to provide responses to this RAI within 30 days of the date of this letter. If you need further clarification concerning this request, please contact Dr. Tai Huang at (301) 415-2867..
Sincerely, i
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James H. Wilson, Senior Project Manager Generic issues and Environmental Projects Branch Division of Reactor Program Management Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ encl:: See next page I
R. Reda May 12. 1998 You are requested to provide responses to this RAI within 30 days of the date of this letter. If you need further clarification concerning this request, please contact Dr. Tai Huang at (301) 415-2867.
Sincerely, Original Signed By:
James H. Wilson, Senior Project Manager Generic issues and Environmental Projects Branch Division of Reactor Program Management Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ encl:: See next page DISTRIBUTION:
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REQUEST FOR ADDITIONALINFORMATION FOR GE_ TOPICAL REPORTS NEDC 32601P. AND NEDC-32694R The staff's review of the responses to the RAI (Reference-1) on the SLMCPR Methodology and Uncertainty Topical Reports NEDC-32601P and NEDC-32694P (References 2 and 3) has been completed. While most of the responses are adequate, several of the questions involve technicalissues that have not been completely resolved. These concerns are described in the following.
NEDC-32694P Power Distribution Uncertainties I.10 The 3D MONICORE TIP rejection criteria of Equation (2-25) rejects measured TIPS for which R, < R,- ao. Since these TIPS are in good agreement with the calculated TIP readings, the criterion should be relaxed to allow these TIPS to be accepted orjustification should be given for the rejection.
11.5 The Reference-2 response provides th' LHGR uncertainty analysis. However, in this analysis the axial TIP uncertainty is taken to be equal to the random TIP uncertainty component while in NEDC-32601P (p. 2-9) the TlP uncertainty is taken to be the sum of the random and geometry uncertainty components. Also, the LPRM update uncertainty for the axial node is taken to be the same as for the bundle integrated power and no uncertainty allowance is included to account for TIP rejection. Additionaljustification should be provided to support these assumptions.
NEDC-32601P_SLMCRR Methodology.and. Uncertainties 11.4 The Table-2.2 comparisons of calculated and measured pressure drop indicate a nonconservative 0.75% overprediction of the core flow. Noting that the SLMCPR accounts for random variations rather than systematic biases, how is this flow bias accounted for in the analysis?
11.5 The effect of the fuel rod bowing displacement on the pin power is based on the rod-to-rod power gradient. It is not evident that this approach accounts for the change in the pin power distribution resulting from the bowing displacement. For example, is the gradient calculated for the situation in which the fuel rod is displaced.
II.4/ll.9 The evaluation of the effect of uncertainty in fuel rod density assumes that a 1% error in fuel density results in a 1% error in fuel rod power. A similar assumption is made in the evaluation of the effect of uncertainty in fuel rod enrichment. Additionaljustification should be provided to support these assumptions.
11.10 The response to this question does not indicate how the uncertainty in local fuel exposure is accounted for in the local peaking factor uncertainty.
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t 11.13 i he responte to this question indicates that the errors in neighboring fuel rod powers are o
correlated. While the response discusses the effect on the rods adjacent to the water gap, it is noted that the R-Factor is required for all rods in the fuel bundle. The R-Factor uncertainty should account for the fact that the modeling errors in the calculation of neighboring fuel rod powers is correlated.
Ill.11 The present GETAB methodology assigns the bundle power error to the four bundles l
surrounding the TIP in a correlated manner so that each of the four bundles is perturbed simultaneously by the same amount. In the proposed methodology, the modeling error in these four bundles is assumed to be uncorrelated and the individual bundle powers are varied independently during the. uncertainty propagation. Because of the increased random variability in the proposed methodology the SLMCPR is reduced. Additionaljustification is required to support the assumption that the modeling errors in these four fuel bundles is uncorrelated, j
References l
1.
"Requast for Additional information for GE Topical Reports NEDC-32601P and l
NEDC-32694P," Letter, J. H. Wilson (NRC) to R. J. Reda (GE), dated August 20,1997.
i 2.
" Responses to Request for Additional Information for GE Topical Report NEDC-32694P, l
Power Distribution Uncertainties for Safety Limit MCPR Evaluations", Letter GAW-98-003, G. A. Watford (GE) to Document Control Desk (NRC), dated January 9,1998.
4 3
" Responses to Request for Additional Information for GE Topical Report NEDC-32601P, Methodology and Uncertainties for Safety Limit MCPR Evaluations", Letter GAW-98-002, G. A. Watford (GE) to Document Control Desk (NRC), dated January 8,1998.
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GE Nuclear Energy
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Gary L. Sozzi, Manager Technical and Modification Services GE Nuclear Energy 175 Curtner Avenue San Jose, CA 95125 j
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George B. Stramback GE Nuclear Energy 175 Curtner Avenue San Jose, CA 95125 David W. Reigle GE Nuclear Energy 175 Curtner Avenue San Jose, CA 95125 j
1 James F. Klapproth
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GE Nuclear Energy j
175 Curtner Avenue j
San Jose, CA 95125 Ralph J. Reda, Manager i
Fuel and Facility Licensing i
i General Electric Company P.O. Box 780 Wilmington, NC 28402 Glenn A. Watford, Manager Fuel Engineering GE Nuclear Energy P.O. Box 780 Wilmington, NC 28402 l
James L. Rash j
GE Nuclear Energy P.O. Box 780 Wilmington, NC 28402
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