ML20203B495
| ML20203B495 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 01/29/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20203B492 | List: |
| References | |
| NUDOCS 9802240303 | |
| Download: ML20203B495 (3) | |
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i-p" UNITED STATES.
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j NUCLEAR REGULATORY COMMISSION e
WASHINGTON, D.C. speeHoo1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENf*3fT NOS. 205 AND 187 TO FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 PUBLIC SERVICE ELECTRIC & GAS CONPANY PHILADELPHIA ELFCTRIC COMPANY l
DELMARVA POWER AND LIGHT C(MPANY i
ATLANTIC CITY ELECTRIC COMPANY g
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SALEM NUCLEAR GENERATING STATION. UNIT NOS. I AND 2 DOCKET NOS. 50-272 AND 50-3H 1
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1.0 INTRODUCTION
By letter dated October 21, 1997, the Public Service Electric & Gas Company (the licensee) submitted a request for' changes to'the Salen Nuclear Generating 4
i Station, Unit-Nos. I and 2, Technical Specifications'(TSs). The requested changes would revise the TSs to require the Reactor' Trip System Powwr Range Nuclear Instrumentation (Low Setpoint) to be operable in Mode 3 (hot shutdown), when the reactor trip breakers are in the closed position and the-i 1
rod control drive system is capable of rod withdrawl.
Currently, the Reactor Trip System Power Range Nuclear Instrumentation.is required to be operable in Modes l=and 2 (power operation and startup, respectively).
'2.0 EVALUATION The NRC staff issued Generic Letter (GL) 93-04, " Rod Control System Failure and Withdrawl of Rod Control Cluster Assemblies," on June 21, 1993, addressing a single failure vulnerability in the Westinghouse solid state rod control system that could cause an inadvertent withdrawl of control rods in a sequence resulting in a power distribution not considered in the design basis analysis.
This GL was issued as ti.e result of a Salem Unit 2 rod control system failure that caused a signal rod to withdraw although the plant' operator Md app 1ad a rod insertion command signal. During its evaluation of this incident and the GL, the licensee conducted a review of the relevant accident analyses, procedures and TSs. The licensee found that, should a control rod withdrawl occur during Mode 3 (hot shutdown), there is a possibility for an inadvertent criticality to occur. On the basis of this possibility, the licensee has revised its startup procedures to require the Power Range Nuclear Instrumentation - low setpoint trip to be operable during Mode 3 if the reactor trip breakers are closed and the control rod drive system is cap:ble of rod withdrawl.
The proposed amendments would incorporate this requirement into the TSs.
9002240303 980129 DR ADOCK 050002 2
. l TS Table 1-1 defines Mode 3 as Kg s 0.95, reactor power = 0, and reactor coolant system temperature 2 350 F.
The licensee;s proposed change would now provide that the Power Range Nuclear Instrumentation reactor trip is operable in Mode 3 during hot control rod testing and rod withdrawl for the approach to criticality (entering Mode 2). This instrumentation does not require TS operability during lower Modes because the reactor coolant system boron concentration is maintained at a level that produces a K s 0.95 for any rod m
configuration.
Section 15.2.1, " Uncontrolled Rod Cluster Assembly Bank Withdrawl from a Subcritical Condition," of the Salem Updated Final Safety Analysis Report (UFSAR) discusses the results of the transient analysis for this fault condition resulting in a power excursion. The maximum reactivity insertion rate analyzed was that occurring with the simultaneous withdrawl of the combination of the two control banks having the maximum combined worth at maximum speed. The power supplied to the banks prevents more than two banks being simultaneously withdrawn. This reactivity insertion rate is also greater than the maximum insertion rate associated with the withdrawl of a part length rod cluster control assembly.
Should this fault occur, the transient analysis relied on the following automatic features to terminate the transient:
(1) Source Range High Neutron Flux Trip (2)
Intermediate Range High Neutron Flux Trip (3) Power Range High Neutron Flux Trip (Low Setting)
(4) Power Range High Neutron Flux Trip (High Setting)
The Power Range High Neutron Flux Trip consists of two independent trip settings, High Setting and Lew Setting. While the High Setting provides protection during power operation, the Low Setting is primarily designed for protection during startup. The Low Setting is autc.natically inserted whenever three of the four Power Range Nuclear Instrumentation (PRNI) channels sense the power level is below 10 percent (i.e., the P-10 interlock). The PRNI circuitry will allow the operators to manually bypass the L1w Setting when two of the four PRNI channels read above 10 percent reactor pow.r. The High Setting remains active at all power levels when the PRNI is operable. The bounding analysis described in UFSAR Section 15.2.1 indicates that the Power Range High Neutron Flux Trip (Low Setting) will prevent the fuel limits from being exceeded during the above transient.
Since the licensee's proposed change incorporates the requirement into the TSs that are in the plant procedures and increases Mode operability requirements, the NRC staff finds that the proposed changes are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New Jersey State official was notified of the proposed issuance of the amendments. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to 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 Cosmiission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public cosmient on such finding (62 FR 68146). Accordingly. the amendments meet the eligibility criteria for i
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.
5.0 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' hot be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
P. Milano Date: January 29, 1998 R
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