ML20212B722

Safety Evaluation Supporting Amends 224 & 205 to Licenses DPR-70 & DPR-75,respectively

ML20212B722
Person / Time
Site:	Salem
Issue date:	09/14/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20212B721	List: ML20212B718 ML20212B722
References
NUDOCS 9909200224
Download: ML20212B722 (4)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 224 AND 205 TO FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 PUBLIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY SALEM NUCLEAR GENERATING STATION. UNIT NOS 1 AND 2 DOCKET NOS. 50-272 AND 50-311

1.0 INTRODUCTION

By letter dated July 2,1999, the Public Service Electric & Gas Company (the licensee) submitted a request for changes to the Salem Nuclear Generating Station, Unit Nos.1 and 2, Technical Specifications (TSs). The requested changes would delete TS 3/4.3.4,

" Instrumentation - Turbine Overspeed Protection," and its associated Bases and relocate the requirements in accordance with the guidance in Generic Letter 95-10. " Relocation of Selected Technical Specifications Requirements Related to Instrumentation." The licensee has committed to relocate these requirements to the Updated Final Safety Analysis Report (UFSAR) such that future changes could be made under Section 50.59 of Title 10 of the Code of Federal Reaulations (10 CFR 50.59).

Section 182a of the Atomic Energy Act, as amended (the "Act"), requires applicants for nuclear power plant operating licenses to incorporate TSs as part of the license. The Commission's regulatory requirements related to the content of the TSs are set forth in 10 CFR 50.36. That regulation requirts that the TSs include items in five categories, including (1) safety limits, limiting safety system settings, and limiting control settings, (2) limiting conditions for operation, j

(3) surveillance requirements, (4) design features, and (5) administrative controls. The q

regulation does not specify the particular TSs to be included in a plant's license.

The four criteria defined by 10 CFR 50.36 for determining whether a particular matter is required to be included in the TS limiting conditions for operations (LCOs) are as follows:

(1) installed instrumentation that is used to detect, and indicate in the control room, a signification abnormal degradation of the reactor coolant pressure boundary; l

(2) a process variable, design feature, or operating restriction that is an initial condition of i

a Design Basis Accident or Transient analysis that either assumes the failure of, or presents a challenge to the integrity of a fission product barrier:

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(3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a Design Basis Accident or Transient that either assumes the failure of, or represents a challenge to the integrity of a fission product barrier; (4) a structure, system, or component which operating experience or probabilistic safety assessment has shown to be significant to public health and safety.

Existing TS requirements which fall within or satisfy any of the criteria must be retained in the TSs; those requirements which do not fall within or satisfy these criteria may be relocated to other licensee-controlled documents.

2.0 EVALUATION

2.1 Background

2.1.1 Main Turbine The main turbine portion of the Salem turbine generator system at each unit consists of one double-flow high pressure (HP) element in tandem with three double-flow low pressure (LP) elements. Main steam enters the HP element through four main turbine stop and control valve assemblies. The control valves regulate steam flow to the turbine, and either the stop valves or the control valves can be used to isolate steam under abnormal conditions. The exhaust from the HP element is directed through six moisture separator reheaters (MSRs) and then through six reheat stop and intercept valve assemblies prior to entering the LP elements. The reheat stop and intercept valves are provided for steam isolation of the LP elements.

2.1.2 Turbine Electro-Hydraulic Control (EHC) System The EHC system regulates the flow of steam to the turbine by movement of the control valves.

The EHC system controller positions the control valves to regulate turbine speed when the generator is not connected to the grid (wide-range speed control) and the generator electrical output (load control) after the main generator output breakers are closed.

An auxiliary governor section (overspeed protection controller or OPC) of the EHC controller i

also prevents turbine overspeed in the event of a complete or partial loss of load which tes not result in a turbine trip. The OPC responds when (1) turbine speed exceeds 103 percent of rated speed and no turbine trip has occurred or (2) its load drop anticipator circuit senses LP reheat pressure ) 30 percent of rated, the generator breakers are open, and no turbine trip has occurred. The OPC monitors LP turbine inlet pressure when the generator breakers are open since high inlet pressure is an indication of excessive steam contained in the MSRs. The OPC rapidly closes both the control valves and the reheat intercept valves to prevent the unit from reaching the mechanical overspeed trip settino.

2.1.3 Turbine Protection System The turbine protection system monitors the operation of the main turbine and provides protection for the unit by tripping the turbine if an unsafe condition is detected. Upon the trip of one of the turbine protective devices which are independent of the EHC electronic controller, all

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. the turbine valves are tripped close in addition to other protective features, this system includes independent mechanical and electrical overspead trips. The mechanical overspeed trip mechanism will actuate at 103 percent of rated speed to initiate fast closure of all turbine valves. An electrical Nerspeed trip (part of the solenoid trip subsystem) provides additional protection since it will actuate at 110 percent of rated speed with both generator breakers open.

2.2 Evaluation The current TS 3.3.4, " Turbine Overspeed Protection," states that at least one turbine overspeed protection system shall be operable in Modes 1,2, and 3 (Power Operation, Startup, and Hot Standby). The surveillance requirements provide for periodic testing of the systems which direct observation of the movement of all turbine valves. In particular, SR 4.3.4.2 requires the overspeed protection system,o be verified operable: (1) prior to admitting steam to the turbine during each startup unless performed within the past 7 days, (2) following startup, within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of attaining the manufacturer's recommended power level for performing turbine valve testing, and (3) at a frequency not to exceed 1 year. These frequencies are consistent with the methodology presented in WCAP-11525,"Probabilistic Evaluation of Reduction in 3

Turbine Valve Test Frequency." Further, SR 4.3.4.3 requires the channel calibration of the turbine overspeed protection system at least once per 18 months and the disassembly and

- inspection of at least one of the turbine valves at least once per 40 months.

In its July 2,1999, letter, the licensee prop 0 sed removing TS 3.3.4, " Turbine Overspeed Protection," and the associated surveillance requirements and Bases section and relocating the requirements to a licensee-controlled document, the UFSAR. Once located in the UFSAR, any changes to these requirements would be controlled in accordance with the requirements of 10 CFR 50.59. The licensee also stated that turbine testing would continue to be performed at a frequency consistent with WCAP-11525. Further, the licensee indicated that performance of turbine stop valve testing in accordance with WCAP-11525 permits the testing and inspection frequencies to be optimized such that unnecessary testing and inspections will be reduced; thereby reducing the probability of plant transients.

Although the analyzed design basis accidents and transients include a variety of system failures and conditions which might result from turbine overspeed events and potential missiles striking various plant systems and components, the system failures and plant conditions are much more likely to be caused by events other than turbine failures in view of the low likelihood of turbine missiles, assumptions related to the turbine overspeed protection system are not part of an initial condition of a design basis accident or transient that either assumes failure of, or presents -

a challenge to, the integrity of a fission product barrier. The turbine overspeed protection system is not relied upon in the design basis accident or transient analyses as a primary success path to mitigate such events.

Operating experience and probabilistic safety assessment have demonstrated that proper maintenance of the turbine valves is important to minimize the potential for overspeed events

. and turbine damage. However, this experience has also shown that there is a low likelihood of significant risk to public health and safety because of turbine overspeed events. Further, the potential for and consequences of turbine overspeed events are diminished by factors such as the orientation of the turbine relative to plant stiuctures and equipment, the proper perforrrfk' ce n

of the inservice testing programs, and surveillance programs for the turbine valves derived from manufacturer's recommendations.

g 0 Accordingly, the NRC staff has concluded that the requirements for turbine overspeed controls do not meet the 10 CFR 50.36 criteria and need not be included in the TSs. Therefore, the removal of the turbine overspeed protection instrumentation requirements from the TSs and relocation to the UFSAR is acceptable. Any subsequent changes to the provisions may be controlled pursuant to 10 CFR 50.59.

The NRC staff also notes that the proposed removal of the requirements in TS 3/4.3.4 would be consistent with the guidance in NUREG-1431, " Improved Standard Technical Specifications, Westinghouse Plants."

The NRC staff has no objection to the deletion of the Bases associated with TS 3/4.3.4.

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.

4.0 ENVIRONMENTAL CONSIDERATION

The amendments change a rec,uirement 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 j

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 consideration, and there has been no public comment on such finding (64 FR 43776). Accordingly, the amendments meet the j

eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR i

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 not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: P. Milano Date: September 14, 1999

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