ML20196A616
| ML20196A616 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/23/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20196A609 | List: |
| References | |
| NUDOCS 9811300079 | |
| Download: ML20196A616 (3) | |
Text
_ - _ -
neg k
UNITED STATES g
s NUCLEAR REGULATORY COMMISSION -
WASHINeToN, D.C. SOOSS 40M SAFETY EVALUATION BY THE OFFICE OF NUCI FAR REACTOR REGULATION RELATED TO AMENDMENT NO.136TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND Fl FCTRIC COMPANY THE CITY OF RIVERSIDE. CALIFORNIA THE CITY OF ANAHEIM. CALIFORNIA SAN ONOFRE NUCI FAR GENERATING STATION. UNIT 3 DOCKET NM302
1.0 INTRODUCTION
l By application dated September 22,1998, Southem Califomia Edison Company, et al. (SCE or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. NPF-10 and NPF-15) for San Onofre Nuclear Generating Station, Unit Nos. 2 and 3. The current technical specifications (TS) for the operating bypass removal bistable for Logarithmic Power Level - High, Reactor Coolant Flow - Low, Local Power Density -
High, and Departure from Nucleate Boiling Ratio - Low currently use " THERMAL POWER" as the input process parameter. Thermal power is a term that includes decay heat,~ which is not a directly measurable parameter, thus is not a reasonable parameter for automatically establishing bistable conditions. The proposed changes would revise the input process
- parameter for these bistables from " THERMAL POWER" to " logarithmic power."
In their September 22,1998, amendment request, SCE stated that the proposed changes were required to allow SONGS Unit 2 to restart from the current forced outage. The staff reviewed the circumstances applicable to the amendment request and determined that the' circumstances met the requirements of 10 CFR 50.91 for review of the amendment request on an emergency basis. The Commission subsequently approved the proposed changes, and by letter dated September 25,1998, issued License Amendment No.142 to Facility Operating License No.
NPF-10 for SONGS Unit 2. Since the emergency review provisions provided in 10 CFR 50.91 did not apply to SONGS Unit 3, the staff has reviewed the amendment request for SONGS Unit 3 in accordance with the normal process requirements provided in 10 CFR 50.91. This safety evaluation documents the staffs review of the proposed changes for SONGS Unit 3.
9811300079 981123 P
PDR ADOCK 05000362 P
!L
O
2.0 BACKGROUND
- TS Table 3.3.1-1, " Reactor Protective System Instrumentation," includes Notes "a" and "d" that identify operating bypass permissive ano enable bistable values. Note "a" permPs bypassing the Logarithmic Power Level - High (log pcwor) trip when THERMAL POWER is > 1 E-4% rated thermal power (RTP). Note "a" also requires automatic enable (specified in the TS as
" automatic removal" of the bypass) of the log power trip to occur when THERMAL POWER is <
1E-4% RTP during a decrease in reactor power. Note "a"is applicable in Mode 2. Note "d" permits bypassing the Reactor Coolant Flow-Low, Local Power Density - High, and Departure From Nucleate Boiling Ratio - Low (RCS Flow /LPD/DNBR) trips when THERMAL POWER is <
1E-4% RTP. Note "d" also requires automatic enable of the RCS Flow /LPD/DNBR trips to occur when THERMAL POWER is > 1E-4% RTP during an increase in reactor power. Note "d" is applicable in Modes 1 and 2.
TS 1.1 defines THERMAL POWER as follows:
" THERMAL POWER shall be the total core tcat transfer rate to the reactor coolant."
Thus, " THERMAL POWER" includes the decay heat produced in the core. This definition means that " THERMAL POWER" for SONGS Units 3 will not decay to less than or equal to
.1E-4% RTP for many years after shutdown. In addition, " THERMAL POWER" is not a directly measurable parameter. Since " THERMAL POWER" will not decrease to less than or equal to 1E-4% RTP for normal duration plant outages, TS Table 3.3.1-1, note "d," would require the RCS Flow /LPD/DNBR trip bypasses to be removed during planned startups when SONGS Unit 3 enters Mode 2. These trip setpoints have a wide variability at this power level due to large uncertainties in the measured parameters. This condition is expected to produce a trip signal as soon as the trip bypasses are removed. Therefore strict adherence to the notes as currently written would preclude plant startups of SONGS Unit 3.
3.0 EVALUATION The TS Table 3.3.1-1 notes "a" and "d" require automatic removal of the bypasses under specified conditions, which would require the use of a measurable parameter. Since the decay heat component of " THERMAL POWER" is not directly measurable, it is not suitable for use for an automatic action. The use of logarithmic nuclear instrumentation instead of " THERMAL POWER" as the process prameter would also make the TS consistent with the design bases for establishing and removiag the bypasses. The SONGS Unit 3 TS 3.3.1 Bases, as well as the Bases for the Standard TS for Combustion Engineering designed plants (NUREG-1432) use logarithmic nuclear instrumentation to establish the 1E-4% RTP bypass / enable. Final Safety Analysis Report (FSAR) Section 7.2 describes the bypass setpoints in terms of power, without specifying the specific parameter used. This section does, however, describe setpoints in terms of measured parameters. In addition, FSAR Section 15.4.1.1.3.B.1 states that the bypass setting of 1E-4% power is established based on logarithmic power. Thus the intended, as well as the only physically possible means of generating a signal from a measured parameter to automatically remove the bypass, and the intended parameter used to determine i
. ~ _ _. _ __. _ _._._
i Since neutron flux is, by design, the correct input process variable for the operating bypass permissive and enable bistable values described in SONGS Unit 3 TS Table 3.3.1-1 notes "a" and "d," the change to replace " THERMAL POWER" with logarithmic power is acceptable.
4.0 STATE CONSULTATION
in accorrlance with the Commission's regulations, the staff consulted with Califomia Stata official for comment on the proposed issuance of the amendment. The Califomia State official had no comment on the proposed amendment.
5.0 ENVIRONMENTAL CONSIDERATION
e The amendment changes a requirement with respect to installation or use of a facility j-component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has
- determined that the amendment involves no significant increase in the amour!.s, 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 amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 56259). Accordingly, the amendment meets 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 amendment.
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 amendment will not be inimical to the
. common defense and security or to the health and safety of the public.
Principal Contributor:- M. Gray
^
Date: November 23,1998