ML20087J198
| ML20087J198 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/15/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20087J196 | List: |
| References | |
| NUDOCS 9508180359 | |
| Download: ML20087J198 (3) | |
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UNITED STATES y+
E' NUCLEAR REGULATORY COMMISSION I
f WASHINGTON, D.C. 20N0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.105 TO FACILITY OPERATING LICENSE NO. NPF-11 AND AMENDMENT NO. 91 TO FACILITY OPERATING LICENSE NO. NPF-18 l-COMMONWEALTH EDISON COMPANY l
LASALLE COUNTY STATION. UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374
1.0 INTRODUCTION
By letter dated January 13, 1995, Commonwealth Edison Company (Comed, the licensee) requested to amend Facility Operating License No. NPF-Il and NPF-18 for LaSalle County Station, Units 1 and 2.
The proposed amendments would revise the pressure alarm setpoint allowable values for the emergency core cooling system (ECCS) and reactor core isolation cooling (RCIC) system " keep filled" pressure instrumentation channels. The purpose of the proposed change is to lower the setpoint allowable values for these parameters to more realistic values based upon calculations performed by the licensee reflecting design changes and system performance. Also, the term "setpoint" is being changed to "setpoint allowable value" to clarify the use of the values.
Additionally, two administrative / editorial changes are included to delete technical specification (TS) footnotes which are no longer applicable.
2.0 BACKGROUND
The Low Pressure Coolant Injection (LPCI) subsystems A, B, and C, the Low Pressure Core Spray (LPCS) system, and the High Pressure Core Spray (HPCS) system constitute the ECCS at LaSalle. These systems provide core cooling-in the event of a break or leak in the nuclear system process barrier. The RCIC system provides core cooling if the reactor becomes isolated from the main condenser and emergency core cooling is not needed.
A design requirement for the ECCS and the RCIC systems is that cooling water flow to the vessel be initiated rapidly when the systems are called upon to perform their function. The lag between the process demand and initiation of flow into the reactor vessel can be minimized by always keeping the pump discharge lines full of water.
In addition, keeping the discharge lines full helps prevent water hammer in the piping system.
To ensure the lines are kept full, a water leg pump is provided for each ECCS division and for the RCIC system.
Indication is provided in the main control room as to whether these water leg pumps are operating, and a pressure switch on discharge lines ef the ECCS and RCIC pumps provides an alarm in the Control Room on low discharge line pressure.
If an ECCS or RCIC discharge line " keep I
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filled" alarm is activated, system operability is determined by performing a surveillance that involves venting at the high noint vent to verify that the system discharge piping is full of water. The setpoints for the " keep filled" pressure alarms are governed by TS 4.5.1.c.2 for for the ECCS systems and TS 4.7.3.c.3 for RCIC. The existing alarm setpoints do not accommodate the current plant design and result in low pressure alarms even though keepfill systems are operating properly. This results in unnecessary burdens on plant personnel because they are required, by TSs, to periodically perform the alternate surveillance of venting the systems at the high point vent.
3.0 EVAltlATION The licensee has proposed to change the " keep filled" alarm setpoints contained in TS 4.5.1.c.2 and TS 4.7.3.c.3 for the ECCS and RCIC systems.
These alarm setpoints make operators aware that the systems may not be full of water and, therefore, the systems may be vulnerable to water hammer or delayed water delivery to the reactor coolant system in the event the systems are actuated. The instrumentation serves to monitor system readiness, but does not serve any direct event mitigation or post-accident instrumentation function.
In addition to the " keep filled" alarms, problems with ECCS or RCIC discharge line fill systems can be detected by annunciators associated with trips of the water leg pumps, periodic surveillances of the water leg pumps perform 6d in accordance with the inservice test (IST) programs, and periodic 15 surveillances.
The licensee has performed analyses to determine the required " keep filled" alarm setpoints to ensure the ECCS and RCIC systems remain full of water.
These analyses were deemed necessary to accommodate current plant configurations which include the use of the suppression pool as the suction source for HPCS and RCIC.
The " keep filled" alarm setpoints for HPCS and RCIC are reduced from the current values in the TS to address the reduced suction pressure associated with the suppression pool compared to the previously assumed suction source, the condensate storage tank.
The change in the suction sources results in unnecessary " keep filled" alarms with the existing TS values.
The alarm setpoints for the LPCI and LPCS systems have been reduced to a smaller degree as a result of the licensee's analyses.
The setpoint analyses have been performed in an attempt to optimize the setroints such that the function of ensuring system readiness is maintained, but the occurrence of unnecessary or nuisance control room alarms is minimized.
The licensee has based the proposed ECCS and RCIC discharge line " keep filled" alarm setpoint allowable values on the head of water between the centerline of the pump discharge nozzle and the associated system high point vent, the installed instrumentation, and related measuring and test equipment.
The analytical limit, setpoint allowable value, and calibration setpoint for each instrument channel were documented in licensee calculations that account for various uncertainties and required allowances. These analyses were performed in accordance with established licensee procedures that are based upon applicable NRC regulatory guides and accepted industry standards.
Based upon the description of the licensee's analyses, the staff finds the proposed ECCS and RCIC " keep filled" alarm setpoints acceptable.
f In addition to the changes in the alarm setpoints, the licensee has proposed several editorial changes.
The term "setpoint" in TS 4.5.1.c.2 and TS 4.7.3.c.3 is proposed to be changed to "setpoint allowable value" to clarify the TS requirements related to the " keep filled" alarms.
The licensee has also proposed to delete footnotes related to LaSalle, Unit 1 TS 4.5.1 and TS 3.7.3 for both units. The affected footnotes are no longer relevant due to the temporary nature of the applicable condition or subsequent TS amendments.
The staff has reviewed the proposed changes and determined that they are editorial or clarifying in nature and are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State oft cial was notified of the proposed issuance of the amendments.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change 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 the amendments involve no significant hazards consider-ation, and there has been no public comment on such finding (60 FR 11129).
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 or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: William D. Reckley Date:
August 15, 1995 I
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