ML20129A931
| ML20129A931 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 07/01/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20129A910 | List: |
| References | |
| NUDOCS 8507150415 | |
| Download: ML20129A931 (3) | |
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UNITED STATES
[
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. NUCLEAR REGULATORY COMMISSION jj WASHINGTON, D. C. 20555 f...% d}
SAFETY EVALUATRh AMENDMENT NO. 12 TO NPF-18 LA SALLE COUNTY STATION. Uf'IT 2 DOCKET N0. 50-374 Introduction Ey letter dated June 14, 1985, Ccinnonwealth Edison Company (licensee) requested an emergency change to the La Salle Unit 2 Technical Specifications. The proposed change would revise the response time for the !!ain Steam Line Low Pressure trip function in the Technical Specifications Table 3.3.2-3 from 1 to
-2. seconds.
Presently, La Salle Unit 2 is scheculec to startup on June 24, 1905, anc witFcut hRC action to, approve the response tire from 1 to 2 seconds, the reacter would be delayed from starting up in order to re-install the crigirel non-qualified switches. The licensee estimates reinstallation would recuire a delay of 3 days, and woulo also necessitate a forced cutage et least 3 days prior to November 30, 1985 to meet License Concition 2.C.(5) of having all qualified equipment in place.
Evaluation La Salle Unit 2 is shutdown and currently completing surveillance requirements and updating those equipment requiring unit shutdct,n for replacement with environmentally qualifiea equipment.
In late flay, the licensee discovered that the new qualified pressure switches in the Main Steam Lir.e Lou Pressure trip function could not consistently meet the less than or equal to 1 second response time required by the Technical Specitications in Table 3.3.E-3.
The licensee took numerous steps to obtain conformance with the 1 second response time. These steps included testing at various rarp rates, discussions with the instrument supplier and General Electric Company (La Salle's vendor), and additional retesting and varicus configurations (without instrument snubbers and with modified snubbers). All of this effort was to no avail. The switches' average response tirne remains at or about 1.1 seconds.
The Final Safety Analysis Report of the flain Steam Isolation Valve (MSIV) closure transients incluce:
(1) the overpressure aspects from rapid closure frcm 3 seconds of MSIV closure at 105 percent steam flow conditions, anc (2) the long-term MSIV closure where 105 percent steam flow is assured to persist for 30 seconds due to loss of alternating current power and other
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, adverse failures indicating acceptable results. The safety analysis of concern to this Technical-Specification Table 3.3.2-3 A.1.C(2) appcrtions the' response time as follows:
Sensor - 1.0 secono MSIV - 13.0 seccnds (actually Diesel Generutor stert interval dominates the l'SIV actual closure time which is 3 tc 5 seconds).
The safety analysis for the Main Steam Line Lcw Pressure isolation via MSIVs was done at 825 psi pressure (analytical minimum limit to assure validity above the GEXL fuel correlation threshold). The allcwable Technical Specification setpoint is 834 psig and the nominal.setpoint is b54 psig.
At the analytical limit of 825 psi, the 30 second 14SIV closure time (total of sensor and valve ar.d its auxiliaries) is acceptable. At this condition, the present Technical Specification utilizes 14 total seccnds of this 30 second safety enalysis interval. The revised Technical Specification extends
.this utilization to 15 total seconds (2 seconds for the sensor and the sare 13 seccods for the valve) of the 20 second interval. This is an insignificar,t change in.the pre-enalyzed safety envelope because the protective isolaticr action (MSIV closure) occurs prior to the time when the systcn pressure
' decreases to the aralytical limit (625 psi) even frca the lowest allowable Technical Specification value (834 psi).
The purpcse of the icw pressure isolation is.to protect the fuel by restricting reactor operation to the pressure regimes covered by the data base fcr the GEXL ccrrelation. Because the analyses using the 30 second MSIV closure time are still applicable, the staff concludes that use of the GEXL correlation is etill valid.. We find the prcpcsec Technical Specification change acceptable.
EliERGENCY CIRCUMSTANCES The f:FC Prcject Manager was inforned on June 13, 1985, of the need fcr the
- arcncment, and the applicaticn was submitted by letter dated June 14, 1085.
We have reviewed-the facts cencernins this request and conclude that the licensee has made a timely submittal, that reoctor startup would be delayec without NRC action, and that action by the licensee could not preclude this situation without delay of startup.
Final No Significant Hazards Consideration Determinaticn The Conmission has provided guidance concerning the applicaticn of the standaros for determining whether a significant hazards consideraticn exists by providing certain examples (48 FP 14870). The examples of actions involving no significant ha ards consideration include: (vi) a change which may reduce in scrce way a safety margin, but where the results of the change are clearly within all acceptable criteria with respect to the system or component specified in the Stancarc Review Plan. The licensee indicated and the stuff l
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. agrees that increasirg the llain Steam Isolation Low Fressure switch response time frcu 1 to 2 seccnos has no effect on the analyses in Chapter 15 of the Final Safety Analysis Report erd, specifically, the total bain Steca Iselation Valve closure time assumed in these analyses. This increase in allowable respuise tire does not increase the probability of occurrence of any accicent previously evaluated. Eecause substantially more than this ir. crease in response tirae was eccounted for in the previcus safety analyses, this change will not significartly increase the consequences of presicusly analyzed accidents. The sin.ple change in response time for a trip functicn, within the bounds of previously analyzed accidents, dces not create the possiblity of a new accident different from any previously evaluated. Finally, althcugh this change in allowable sensor response time increases the actual tire it takes for IiSIV closure from about 14 secceds to about 15 seconds, this ircrease in closure time is small relative to the closure time assuned in the bounding safety analysis (30 seconds) so that this char.ge does not significantly reduce a safety martin. Accorcingly, the staff has cade a firal determination that this license amendrert involves no significant hazaros consideraticn.
STAFF CGSSULATIGN In accordance with th'e Commission's regulation, consultation was held with the State of Illinois by telephcne cr, June 17, 1988. The State had no ccarents on this action.
Environmental Consideration This amendment involves a change in the installaticr. cr tse cf a facility component located within the restricted area as cefinec in 10 CFR Part 20.
The staff has determinec that the amendment involves ro significant increase in the amounts, and no significant change in the types, cf any efficents that may be released offsite, and that there is r.c significant increase in individual or cumulative occupaticnal radiation exposure. The Concissicr.
Lus nace a final determination that the ererdment~ involves no significant criteria for ~ categorical exclusion set forth in 10 CFR 51.CE(c)(5)gibility hazarcs ccnsiderations. Accordingly, this atencuent meets the eli Pursuant to 10 CFR 51.22(b) no environmental inpact statement or envirorrental assessment need be prepared in connection with the issuanceof this amendment.
Conclusicn The staff has concluded, basec on the considerations discussed above, that:
(1) this license amerdrent involves no significant hazarcs ccnsiderations; (2) there is reasonable assurance that the health and safety of the public will not be endangered by creration in the proposeo manner, anc (:) such activities will be conducteo in compliance with the Commission's regulations and the issuance of this amerdrent will not be inimical to the ccumcn cefense and security or to the health ard safety of the public.
Dated: JUL 01 ggg
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