ML20207P673
| ML20207P673 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/06/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20207P671 | List: |
| References | |
| IEB-86-001, IEB-86-1, NUDOCS 8701200028 | |
| Download: ML20207P673 (3) | |
Text
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'o UNITED STATES 8\\
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NUCLEAR REGULATORY COMMISSION (I
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i SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 98 TO FACILITY OPERATING LICENSE NO. DPR-29 AND AMENDMENT NO. 94 TO FACILITY OPERATING LICENSE NO. DPR-30 COMMONWEALTH EDISON COMPANY AND 1
IOWA-ILLINOIS GAS AND ELECTRIC COMPANY l
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254/265
1.0 INTRODUCTION
By letter dated October 22, 1986, Commonwealth Edison Company (CECO), the licensee for Quad Cities Station Units 1 & 2, has requested an amendment to the Quad Cities Units 1 & 2 Technical Specifications (TS) to modify the Low Pressure Coolant Injection (LPCI) pump flow test requirements from the current three pump test demonstrating 14,500 gpm to a two pump test den'onstrating 9000 gpm. This change is required to support a modification
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to the LPCI pump minimum flow valve control logic to resolve a single failure concern identified in Inspection and Enforcement (IE) Bulletin 86-01: " Minimum Flow logic Problems That Could Disable RHR Pumps" (May 23, 1986).
2.0 EVALUATION-The existing LPCI loop selection logic is such that failure.of either the "A" loop or "B" loop flow sensor would close both the "A" and "B" minimum j
flow valves.
In response to IE Bulletin 86-01, this l'ogic is being modified so that the "A" valve is controlled only by the "A" flow sensor i
and the "B" valve by the "B" sensor.
Figure 1 illustrates the modified configuration. This new configuration, however, results in reduced LPCI flow to the vessel under certain design basis accident conditions.
As an example, consider that during a design basis loss-of-coolant accident (LOCA), after loop selection, both residual heat removal (RHR) loops will be injecting into the unbroken reactor recirculation loop (see attached Figure 1).
If the "A" recirculation loop is broken, RHR loop "B" pumps will becinjccting through the normal injection path to the unbroken recirculation loop "B".
This flow will pass through the "B" flow element and automatically close the minimum flow valve in RHR loop "B".
RHR loop "A" pumps will be injecting through the cross-tie valve to recirculation 1
"B" because the LPCI injection valve to the broken reactor recirculation i
loop "A" will be closed. Since there is no flow going through the RHR 1 cop "A" flow element, the minimum flow valve in RHR loop "A" will remain open. This reduces the rate of flow to the core by an amount equivalent to the flow through the minimum flow line.
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The reduced LPCI flow to the vessel is less than that flow assumed in the current LOCA analysis. Hence, the licensee performed a new analysis to demonstrate compliance with the criteria of 10 CFR 50.46.
L in the current LOCA analyses, the most limiting event is the hypothetical, double-ended recirculation suction line break with an assumed failure of the LPCI injection valve. This scenario assumes no credit for the LPCI pumps; therefore, the proposed change in the LPCI flow has no effect on the core cooling capability for the most limiting event.
The second most limiting break and single failure combination is the Design Basis Accident (DBA) recirculation suction line break with a diesel generator failure.
This scenario reouires one low pressure core spray pump and two LPCI pumps for core cooling.
General Electric has analyzed this event assuming the proposed 9000 gpm flow rate for two LPCI pumps rather than the 9667 ppm flowrate assumed in the initial Appendix K analysis. The results of this analysis indicate that with the revised flow rate, the peak cladding temperature (PCT) increases by 32 F to 179'F. This temperature is well below the Quad Cities limiting break PCT and the ?200"F limit set by 10 CFR 50.46. This is acceptable.
The proposed TS revisions also reouire that a two pump RHR/LPCI test at a flow rate of 9000 gpm be performed every 3 months, rather than the current three pump 14,500 gpm test. The proposed testing is acceptable since it verifies the flow assumed in the analyses; therefore, the proposed TS changes in 3.5/4.5 A.3 are acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change to requirements with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that the amendments involve no significant increase in the amounts, and no significant chance in the types, of any effluents that may be released offsite and
ere is no significant increase in individual or cumulative occupatimm,, diation exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finoing. Accordingly, the 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 environmental impact statement nor environmental assessment need be prepared in connection with the issuance of these emendments.
4.0 CONCLUkkON The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (21 such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
G. Thomes, T. Rotella Dated:
January 6,1987.
3-FIGURE 1.--ILLUSTRATION OF MODIFIED CONFIGURATION
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