ML14192A733
| ML14192A733 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 01/21/1986 |
| From: | Requa G Office of Nuclear Reactor Regulation |
| To: | Utley E CAROLINA POWER & LIGHT CO. |
| References | |
| TAC-57355, NUDOCS 8601230088 | |
| Download: ML14192A733 (5) | |
Text
January 21, 1986 Docket No. 50-261 Mr. E. E. Utley, Senior Executive Vice President Power Supply and Engineering & Construction Carolina Power and Light Company Post Office Box 1551 Raleigh, North Carolina 27602
Subject:
H. B. Robinson Unit 2, Cycle 10 Fuel Misloading Event Analysis (TAC No. 57355)
During our review of the Cycle 10 core reload for the H. B. Robinson Steam Electric Plant Unit 2, you committed to provide a fuel misloading analysis before the end of 1985. By letter dated December 3, 1985, you submitted the Cycle 10 misloading analysis.
We have completed our review of the submittal and find the analysis and the results acceptable. Therefore, we are closing this issue and TAC No. 57355.
A copy of our review and evaluation is enclosed.
Sincerely, Glode Requa, Project Manager PWR Project Directorate #2 Division of PWR Licensing-A Office of Nuclear Reactor Regulation
Enclosure:
Evaluation cc:
See next page DISTRIBUTION Docket File 50-261 BGrimes NRC PDR JPartlow Local PDR GRequa PAD#2 rdg CVogan TNovak ACRS (10)
OELD Tech Branch EJordan Gray File OFC
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OFFICIAL RECORD COPY 8601230088 860121 PDR ADOCK 05000261 P
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Mr. E. E. Utley Carolina Power & Light Company H. B. Robinson 2 cc:
G. F. Trowbridge, Esquire Mr. Dayne H. Brown, Chief Shaw, Pittman, Potts and Trowbridge Radiation Protection Branch 1800 M Street, N.W.
Division of Facility Services Washington, DC 20036 Department of Human Resources P.O. Box 12200 Raliegh, North Carolina 27605 Mr. McCuen Morrell, Chairman Darlington County Board of Supervisors County Courthouse Darlington, South Carolina 29535 State Clearinghouse Division of Policy Development 116 West Jones Street Raleigh, North Carolina 27603 Attorney General Department of Justice Justice Building Raleigh, North Carolina 27602 U.S. Nuclear Regulatory Commission Resident Inspector's Office H. B. Robinson Steam Electric Plant Route 5, Box 413 Hartsville, South Carolina 29550 Regional Administrator, Region II U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street Atlanta, Georgia 30303 Mr. R. Morgan General Manager H. B. Robinson Steam Electric Plant Post Office Box 790 Hartsville, South Carolina 29550
ENCLOSURE H. B. ROBINSON UNIT 2 CYCLE 10 FUEL MISLOADING EVENT ANALYSIS TAC NO. 57355 Introduction During the review of the Cycle 10 reload for the H. B. Robinson Unit 2, the licensee (Carolina Power and Light Company CP&L), at the staff's request, committed to perform a fuel misloading analysis for Cycle 10 in 1985 (Reference 1).
To fulfill this commitment CP&L submitted a misloading event analysis dated December 3, 1985 (Reference 2).
Evaluation The process of fuel loading is governed by administrative procedures, aiming to prevent fuel misloading and make such an event extremely unlikely (Reference 3). Assuming that a fuel assembly has been misloaded, it could be classified in one of two categories, i.e., detectable with incore detector and power distribution survey or undetectable. In this analysis a misloading event which causes more than 20% deviation is considered detectable. A detectable event can be detected at the 30% power mandatory core power map survey. It has been calculated that a detectable event will not violate DNBR at the 30%
power level. A detected misloading will be corrected before core power exceeds 30%, therefore, in the remaining we shall examine the undetectable misloading events.
Continued operation at rated power can result in increased radial peaking factor in excess of the Technical Specifications and, hence, result in violation of the DNBR limit.
The XTGPWR core analysis code was used to calculate a spectrum of fuel assembly misloading events. The analysis focused on core power peaking limits throughout the cycle. If they were calculated not to exceed the Technical Specification no further evaluation was necessary, otherwise the value of the MDNBR was calculated (using the XNB CHF correlation). If the MDNBR is violated then the fuel will experience boiling transition and
failure and the radiological consequences are evaluated. The worst undetectable misloading occurs when the exposed fuel location is filled with fresh fuel containing gadolinia bearing fuel pins. In this instance the FAH has a value of 1.63 at the beginning of cycle and as the depletion proceeds it reaches a peak value of 1.81. This value is less than the estimated 1.94 for the misalignment of a full length control assembly, therefore, under conditions of steady state power generation the MDNBR will remain above the safety limit of 1.17 and no fuel failure is anticipated.
If a Condition II event occurs with an undetectable fuel misloading some fuel failures may be anticipated. Such fuel failures (and the anticipated radiological releases) are bounded by the control rod withdrawal event in which the FAH value is 2.096, and the radiological consequences are acceptable, as discussed in Reference 4.
Summary And Conclusions The fuel misloading submittal for the H. B. Robinson, Unit 2 plant, which CP&L committed to provide during the review of the Cycle 10 reload has been reviewed. Due to refueling administrative procedures, a misloading event is extremely unlikely.
The analysis was divided into two categories, i.e., detectable and undetectable misloadings. The detectable events will be corrected in the core power distribution surveillance; the undetectable were analyzed further. For steady state operation the peak FAH is 1.81 which is less than the 1.94 value of the misaligned control rod, therefore, such misloading will not violate the MDNBR of 1.17. Should a Condition II event occur with a misloaded assembly, fuel damage will result but the radiological consequences will be bounded by the control rod withdrawal event for which the F H value is 2.096. The releases for the control rod withdrawal are a small part of 10 CFR 100 and, therefore, the misloaded assembly analysis is acceptable. The analysis was performed with the XTGPWR code which is approved reloading code and, therefore, is acceptable. The fuel misloading analysis for H. B. Robinson-2 is acceptable.
REFERENCES
- 1. Letter S. R. Zimmerman, CP&L, to S. A. Varga, NRC, dated November 7, 1984 -
Serial NLS-84-472.
- 2.
Letter S. R. Zimmerman, CP&L, to S. A. Varga, NRC, dated December 3, 1985 -
Serial NLS-85-419.
- 3. XN-NF-83-72, Revision 2, "H. B. Robinson, Unit 2, Cycle 10, Safety Analysis Report," Exxon Nuclear Company, July 1984.
- 4.
XN-NF-84-74, Supplement 1, "Plant Transient Analysis For H. B. Robinson, Unit 2 at 2,300 MWt With Increased F Analysis of Control Rod Misoperation Events", Exxon Nuclear Hrporation, July 1984.