ML20137B779
| ML20137B779 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/07/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20137B772 | List: |
| References | |
| NUDOCS 8601160076 | |
| Download: ML20137B779 (4) | |
Text
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION rn E
WASHINGTON, D. C. 20555
%... } SAFETY EVALUATION BY THE OFFICE OF NU SUPPORTING AMENDMENT NO. 32 TO FACILITY OPERATING LICENSE NO.- NPF-11, AND AMENDMENT NO.18 TO FACILITY OPERATING LICENSE NO. NPF-18 COPNONWEALTH EDISON COMPANY LA SALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374
1.0 INTRODUCTION
By letter dated October 11, 1985, Commonwealth Edison Company (licensee) requested amendments to the La Salle Units 1 and 2 Technical Specifications.
The proposed changes are directed at the Limiting Conditions for Operation (LCO) for core monitoring during core alterations, and addresses Source Range Monitor (SRM) operability, via count rate, and fuel assembly loading limits.
It specifically involves Specification 3/4.9.2 and the related Basis for La Salle Units 1 and 2.
2.0 EVALUATION During reload operations the BWR Standard Technical Specifications require minimum count rate levels to be met by the SRM.
In the case of La Salle Units 1 and 2 Technical Specifications, this rate is 0.7 counts /second with a signal to noise ratio of at least 2.
During reload operations in a BWR in which the entire core is to be unloaded, especially if sources are not present, there may be times when there are few fuel assemblies in the core, and this minimum count rate can not be met with the usual SRM.
For this condition other monitors, Fuel Loading Chambers (FLC), usually called " Dunking Chambers", that can be moved from place to place in the core as loading proceeds, are frequently used as a replacement for the SRM.
Without sources even these may not be able to meet the Technical Specifi-cation requirements.
Furthemore, the FLC are an impediment to operations, and it is thus desirable to keep their use to a minimum.
During the pas't several years, several utilities have requested Technical Specification changes to permit loading operations such that the use of FLC and/or sources can be avoided. The reactors include Browns Ferry, Hatch, Susquehanna and Brunswick. As permitted by these changes, the loading operation for full core reloads involving irradiated fuel may begin without minimum count rates for the SRM for a limited number of assembly loadings (determined to be subcritical). These loadings place irradiated fuel 2
adjacent to SRM locations. This provides (e.g., from gamma-neutron reactions) sufficient neutron source.to meet the Technical Specification minimum SRM count rate requirements. After the SRM are thus fully opera-tional, the loading proceeds in the usual. manner, e.g., spiral loading from the center. The initial loading is acceptable because it is not possible to be critical, even with control rods removed.. with the fuel configurations used.
l 373 PDR
' The licensee proposes, for La Salle, to go below the required SRM count rate when there are no more than four fuel assemblies in each core quadrant, loaded around each of the four SRM positions (or alternate FLC positions, if needed),
for either loading or unloading operations.
For example, for a reload in which all fuel assemblies and normal sources have been removed from the core, they first load up to four (as necessary) frradiated assemblies next to each of the four SRM locations, without necessarily meeting the required count rate until this loading is finished. The loading would then continue in nomal fashion, e.g., spiral loading from the core center, and would have to meet the usual counting rate requirement. General Electric (GE) has calculated for La Salle that the configuration of (any GE) four assemblies (2/2 array) at the maximum reactivity condition (as a function of burnup), without control rods inserted and separated from other assemblies by a distance of two fuel cells would have a k,ff of less than 0.95.
Thus the above configuration is well subcritical.
In addition to being subcritical during the loading of assemblies around the SRM, the core loading should be such as to meet the nonnal shutdown margin requirement during the subsequent loading of the remainder of the core. Thus, if any of the irradiated assemblies needed to reach the count rate are not those scheduled to be at the location (e.g., replacing a scheduled fresh assembly, which would not add significantly to the SRM count rate, with an irradiated assembly), they would be selected so that at any subsequent stage of the loading process the normal, required shutdown margin would be maintained, i.e., the substituted assemblies would have reactivities that were no greater than for the scheduled assemblies. These substituted assemblies would be replaced with the: correct assemblies by the end of the loading process.
The proposed La Salle modifications to the SRM count rate requirement and the loading (and unloading) procedures to safely approach the required count rate are the same as (or similar to) those reviewed and approved for previous appli-cations in this area by the other utilities.
Our review indicates that the pre-count configurations should indeed be well subcritical and experience indicates that required count rates should be achieved with the irradiated assemblies next to the SRM.
The Technical Specification change proposed to allow such operation is an addi-tion to Specification 3.9.2 applicability statement (and to the corresponding basis).
It states that the required SRM count rate will not be applicable when there are less than the four groups of four SRM (or FLC) adjacent assemblies in the core.
If FLC are used, the co1 figurations are suitably separated by a distance of at least two fuel cells. This is a suitable implementation of the above considerations.
i The primary reason for the licensee wanting the change is to eliminate the need for. sources and to minimize the need for FLC_ (" Dunking Chambers") during loading operations.
The primary basis for the safety of the requested change is that the core will be well subcritical during the loading of the initial assemblies, and subsequent loading will be well monitored by the SRM. Our review has con-cluded that this process is acceptable and that the requested Technical Specifi-cation changes appropriately implement the process and are acceptable.
3.0 EFVIRONMENTAL CONSIDERATION These amendments involve a change in use of facility components located within the restricted area as defined in 10 CFR Part 20 and changes surveil-lance requirements. The staff has determined that these amendments involve no significant increase in the amounts, and no significant changes in the types, of any effluents-that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there have been comments in the nature of clarification from the State of Illinois by telecon. These comments were clarified in this telecon. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environ-mental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
4.0 CONCLUSION
The Commission made a proposed determination that the amendments involve no significant consideration which was published in the Federal Register (50 FR 48211) on November 6,1985, and consulted with the state of Illinois.
No public comments were received, and the state Illinois did not have any comments.
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and (2) public such activities will be conducted in compliance with~the Commission's regula-tions and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Howard S. Richings Dated: JAN 0 7 586
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