ML20213G477
| ML20213G477 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/11/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20213G475 | List: |
| References | |
| NUDOCS 8705180310 | |
| Download: ML20213G477 (4) | |
Text
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=r UNITED STATES
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 4 TO FACILITY OPERATING LICENSE NO. NPF-39 PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION, UNIT 1 DOCKET NO. 50-352
1.0 INTRODUCTION
By letter dated February 11, 1987, Philadelphia Electric Company (the licensee) req e sted an amendment to Facility Operating License No. NPF-39 i
for the Limerick Generating Station, Unit 1.
The proposed amendment would change the TecFnical Specifications (TS) for the Limerick Generating Station, Unit 1 by revising the current requirements of TS 3.9.2 and Table 3.3.6-1 for a minimum Source Range Monitor (SRM) detector count rate when 16 or fewer fuel assemblies are in the reactor.
Tne licensee has scheduled the first refueling outage to begin nn May 16, 1987. During the outage, a complete core offloading is planned in order The to more efficiently complete and acconnodate refueling (outaa)e work.
fuel assemblies adjacent to the Source Range Monitors SRMs, being the last fuel assemblies to be removed, would cause the loss of SRM detector count rate contrary to the reouirements of the current TS 3/4.9.2, which require that a minimum SRM detector count rate be maintained at all times during core alterations. This application requests a revision to the requirement for a minimum SRM cnunt rate when sixteen or fewer assemblies are in the core so as to pemit complete core offloading. The j
proposed TS changes consist of a footnote to be added to the bottom of I
pages 3/4 3-59, 3/4 9-3 and 3/4 9-4.
The footnote allows the SRM count I
rate to decrease below 3.0 cps (0.7 cps when the signal-to-noise ratio is greater than or equal to 2) whenever sixteen or fewer fuel assemblies are in the core ad.iacent to the SRMs. A change is also made to the TS BASES 3/4.9.2 which further describes how the fuel is to be offloaded and reloaded without the currently required minimum SRM count rate.
The licensee states that the SRM system provides neutron f}ux infomation during startup and low flux level operations; monitors neutron flux level 7
during refueling operations; provides protection against high neutron flux during the approach to criticality; and, monitors neutron flux through the overlap into the Intermediate Range Monitoring System. The SRM functions addressed by the proposed amendment are related to its use in the refueling mode.
87051e0310 870511 PDR ADOCK 05000352 P
2.0 EVALUATION The changes are directed at the Limiting Conditions for Operation.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 related Basis, and Table 3.3.6-1.
During reload operations the Technical Specifications require minimum count rate levels to be met by the SRM. 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, when this minimum 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
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loading proceeds, are frequently used as a replacement for the SRM.
Without sources, even these may not be able to meet the Technical Specificetion requirements. Furthennore, the FLC are ar impediment to operations and it is thus desirable to keep their use to a minimum.
During the past several years several utilities have requested Technical Specification changes to permit loadirg operations such that the use of FLC and/or sources can be avoided. The reactors include Peach Bottom, i
Browns Ferry, Hatch, Susquehanna and Reunswick. An example of such a i
procedure and relevant background and bases are discussed in the staff's SER for the most recently approved revision for Browns Ferry. As pernitted by these changes, the loading operation for full core reloads involving irradiated fuel may begin without minimum count rates for the SRM for a linited number of assembly loadings (determined to be suberitical).
These loadings place irradiated f,uel adjacent to SRM locations. This provides (e.g., # rom gamma-neutron reactions) sufficient neutron source to meet the Technical Specification minimum SRM count rate requirements.
After the SRM is thus fully operational 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.
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PEco proposes, for Limerick, to be allowed to go below the required SRM
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count rate when there are not more than four fuel assemblies in each core quadrant, loaded around each of the four SRM positions for either leading 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) irradiated 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 nonna!
fashion, e.g., spiral loading from the core center, and would have to meet the usual counting rate requirement. General Electric has calculated that the configuration of (any GE) four assemblies (2x2 arrey) at the maximum reactivity condition (as a function of burnuo), without control rods inserted and separated from rther assemblies by a distance of two fuel cells would have a k,ff of less than 0.95. Thus the above configuration is well suberitical I
The proposed Limerick 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 applications in this area by the other utilities. Our review indicates that the pre-count configurations should indeed be well sub-critical and experience indicates that required count rates should be achieved with the irradiated assemblies next to the SRM.
The Technical Specification changes proposed to allow such operation is a
" note" addition to the 3.9.2 applicability statement (and to the corre-sponding basis) and tn Table 3.3.6-1.
It states that the required SRM count rate will not be applicable when there are less than the (previnusly discussed) four groups of four SRM adjacent assemblies in the core. This is a suitable implementation of the above considerations and is acceptable.
Conclusion PECo has requested Technical Specification changes for Limerick which would remve during the loading (unloading) of the first (last) fuel assemblies (ad.iacent to the SRM) the requirement that the SRM meet.a minimum count rate with fuel in the core. Other loading requirements will be unchanged. The primary reason for 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 reouested change is that the core will be well suberitical during the loading of the initial assemblies, and subsequent loading will be well monitored by the SRM. Our review has concluded that this process is acceptable and that the requested Technical Specification changes appropriately implement the process and are acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
I This amendment involves a change to a requirement with respect to the
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irstallation or use of a facility component located within the restricted I
area as defined in 10 CFR Part 20. The staff has detemined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that mey 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 this amerdment involves no significant hazards consideration and there has been no public comment en such finding.
Accordingly, this amendment meets the eligibility criteria for categorical exclusionsetforthin10CFR51.22fc)(9). Pursuant to 10 CFR 51.22(b),
l no environmental impact statement nor environmental assessment need be l
prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of tha
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-4 public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimicel to the conron defense and the security nor to the health and safety of the public.
Prinicipal Contributor:
H. Richings Dated: May 11, 1987 il 5
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