ML20080H268
| ML20080H268 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 02/14/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18040A153 | List: |
| References | |
| NUDOCS 9502160303 | |
| Download: ML20080H268 (5) | |
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20044-0001
\\ *... /g SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDNENT N0, 63 TO FACILITY OPERATING LICENSE NO. NPF-69 NIAGARA MOHAlfK POWER CORPORATION l
NINE MILE POINT NUCLEAR STATION. UNIT 2 i
i DOCKET NO. 50-410
1.0 INTRODUCTION
By letter dated November 3,1993, Niagara Mohawk Power Corporation (the licensee or NNPC) submitted a request for changes to License Condition 2.C.(4) j and to the Nine Mlle Point Nuclear Station, Unit 2 (NMP-2) Technical Specifications (TS). The requested changes would modify License Condition 2.C.(4), " Turbine System Maintenance Program," and would delete TS 3/4.3.8,
" Turbine Overspeed Protection System," and its associated Bases. License Condition 2.C.(4) required the licensee to submit for NRC approval a turbine system maintenance program based on the manufacturer's calculations of missile generation probabilities. The proposed change to License Condition 2.C.(4) would indicate that this requirement has been satisfied. The deletion of TS 3/4.3.8 would provide the Itcensee with the flexibility to irplement the manufacturer's recommendations for turbine steam valve surveillance test requirements. Surveillance test requirements for the turbine steam valves based on the manufacturer's recommendations would be contained'in the Updated Safety Analysis Report.
Section 182a of the Atomic Energy Act (the "Act") requires that applicants for nuclear power plant operating licenses state TS and that these TS be included as a part of the license. The Commission's regulatory requirements related to the content of TS are set forth in 10 CFR 50.36. That regulation requires that the TS include items in five specific categories, including (1) safety i
limits, limiting safety system settings and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls and states also that the Commission may include such additional TS as it finds to be appropriate.
However, the regulation does not specify the particular TS to be included in a plant's license.
The Commission has provided guidance for the contents of TS in its " Final Policy Statement on Technical Specifications Improvements for Nuclear Power Reactors" (" Final Policy Statement"), 58 FR 39132 (July 22,1993), in which the Commission indicated that compliance with the Final Policy Statement satisfies Section 182a of the Act.
In particular, the Cosatssion indicated that certain items coulo be relocated from the TS to licensee-controlled documents, consistent with the standard enunciated in Portland General Electric Co. (Trojan Nuclear Plant), ALAB-531, 9 NRC 263, 273 (1979).
In that case, the Atomic Safety and Licensing Appeal Board indicated that " technical specifications are to be reserved for those matters as to which the imposition 9502160303 950214 PDR ADOCK 05000410 PDR
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l of rigid conditions or limitations upon reactor operation is deemed necessary to obviate the possibility of an abnormal situation or event giving rise to an ismediate threat to the public health nid safety.
Consistent with this approach, the Ffnal Policy Statement identified four criteria to be used in determining whether a particular satter is required to be included in the TS, as follows: (1 Installed instrumentation that is used to detect, and indicate in the con) trol room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an inttial condition of 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; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitipute a Design Basis Accident or Transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (4) a structure, system, or component which operatingexperienceorprobabilisticsaf,etyassessmenthasshowntobe significant to public health and safety.
As a result, existing Limiting Condition for Operation (LCO) requirements which fall within or satisfy any of the criteria in the Final Policy Statement must be retained in the TS, while those LCO requirements which do not fall within or satisfy these criteria may be relocated to other, licensee-controlled documents.
2.0 EVALUATION 2.1 License Condition 2.C.(4)
License Condition 2.C.(4), ' Turbine System Maintenance Program,' of NMP-2 Facility Operating License NPT-69 required NMPC to submit for NRC approval, by October 31, 1989, a turbine system maintenance program based on the manufacturer's calculations of missile generation probabilities. The proposed change to License Condition 2.C.(4) would state that the required program had been submitted on October 30, 1989, and had been approved by NRC letter dated March 15, 1990.
NMPC submitted the required program in a letter dated October 30, 1989. The program submitted by NMPC is based ori the results of a probabilistic evaluation of low pressure turbines performed by the General Electric Company (GE). GE used the methodology of th'.tir proprietary report, " Probability of Missile Generation in General Elect.ric Nuclear Turbines," dated January 1984 to perform this evaluation. By istter dated March 15, 1990, the NRC staff informed NMPC that we had reviewed the licensee's turbine system maintenance program and had concluded that License Condition 2.C.(4) had been satisfied.
the Camelselon recently promulpeted a proposed chance to 10 Cf t 50.36, pursuant to elch the rute would be amended to codify and incorporate these criterle (59 f t 68180, septemer 20, 1994). The Commission's finst Policy Statement specified that the teactor Core Isolation Cocling, Isolation n
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Therefore, we conclude that the proposed change to License Condition 2.C.(4) is acceptable, f4 2.2 TS 3/4.3.8 l!
The NNP-2 turbine generator has several sets of steam valves to control i
f turbine speed during normal operation and to protect it from overspeed durin N
abnormal operations. These valves are the four high pressure Turbine Contro
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Valves, the four high pressure Turbine Stop Valves, and the six Turbine Combined stop and Intercept Valves all of which are controlled during normal operation by the turbine Electrohydraulic Control (EHC) System.
[J The Turbine Overspeed Protection System consists of separate mechanical and electrical sensing mechanisms each capable of independently initiating fast l
closure of the turbine steam valves during abnormal conditions. The i
mechanical overspeed trip will actuate to trip the turbine and initiate fast F
closure of the turbine steam valves at 110 percent of rated speed. The i
electrical overspeed trip (also called the backup overspeed trip) provides an i
additional overspeed trip and additional overspeed protection since it will i
actuate at 112 percent of rated speed.
TS 3/4.3.8 requires at least one Turbine Overspeed Protection System to be OPERABLE in OPERATIONAL CONDITIONS 1 and 2 and provides surveillance requirements for periodic testing and inspection of the turbine steam valves.
The surveillance requirements include weekly cycling of each of the valves through at least one complete cycle. Cycling of the valves introduces the potential for causing plant transients which are detrimental to plant safety.
In its submittal of November 3,1993, MPC proposed that TS 3/4.3.8 and its associated Bases be deleted. The proposed change would also relocate the surveillance requirements to the NMP-2 Updated Safety Analysis Report. The relocated surveillance requirements would be based on the manufacturer's recoaniendations and. operational experience. Surveillance testing in accordance with the' manufacturer's recomunendations will permit NMPC to optimize testing and inspection frequencies such that unnecessary testing and inspections will be reduced. Reduction of unnecessary testing and inspections will assist in reducing plant transients and may thereby enhance safety.
To date, the saintenance and test histories of the turbine steam valves have been satisfactory.
A favorable turbine orientation exists at NMP-2. The center of the reactor building is on a line extended through the longest axis of the turbine generator; this orientation minimizes the possible impact of a turbine fragment on safety-related equipment. The potential effects of turbine missiles were evaluated in Section 3.5.1.3 of NUREG-1047, " Safety Evaluation Related to the Operation of the Nine Mile Point Nuclear Station, Unit 2."
In that evaluation, the NRC staff determined that NMPC should develop and submit to the NRC a turbine system maintenance program based upon manufacturer's I
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recommendations by October 31, 1989. This program was required by License i
Condition 2.C.(4) and was approved by NRC letter dated March 15, 1990. The
- r NUREG-1047 evaluation also concluded that with the im>lementation of this k
turbine system maintenance program, the overall probaallity for unacceptable
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damage by turbine missiles for NMP-2 is considered acceptable.
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The NRC staff also notes that the proposed deletion of TS 3/4.3.8 would make I
the HMP-2 TS consistent with the guidance provided in the NRC's Standard j
Technical Specifications, General Electric Plants, BWR/6 (NUREG-1434) in that y
the NRC's Standard Technical Specifications do not include TS requiring the l-operability of a Turbine Overspeed Protection System.
The licensee has prososed changes to TS 3/4.3.8 to remove the recuirements
.,i related to the operasility of the turbine overspeed controls, anc related ll surveillance requirements.
In the amendment application, the licensee committed to include the surveillance program into Section 10.2.2.2 of the j
Updated Safety Analysis Report (USAR).
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The turbine is equipped with control valves and stop valves which control p
turbine speed during normal duringabnormalconditions.plantoperationandprotectitfromoverspeed The turbine overspeed protection systes consists of separate mechanical and electrical sensing mechanisms which are capable of j
initiating fast closure of the steam valves. Currently TS 3/4.3.8 requires particular operability and surveillance requirements for these steam control and stop valves to minimize the potential for fragment missiles that might be generated as the result of a turbine overspeed event. The licensee has proposed to relocate these provisions to tie USAR such that future changes to l
the operation and surveillance of the turbine overspeed features could be i
changed under 10 CFR 50.59.
Although the design basis accidents and transients include a variety of system i
failures and conditions which might result from turbine missiles striking various plant systems and equipment, system failures and plant conditions 1'
could be caused by other events as well as turbine failures. In view of the low likelihood of turbine alssiles this scenario does not constitute a part of the primary success path to prevent or altigate such design basis accidents and transients. Similarly, the turbine overspeed control is not prt of en initial condition of a design basis accident or transient that eitner assumes the failure of or presents a challenge to the integrity of a fission product barrier.
Probabilistic safety assessments (PRA) and operating experience have demonstrated that proper maintenance of the turbine overspeed control valves is important to minimize the potential for overspeed events and turbine damage; however that experience has also demonstrated that there is 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 the favorable orientation of the turbine, relative to the likely path of any turbine missiles, and the licensee's inservice inspection program, which must comply with 10 CFR 50.55(a), and a surveillance program for the turbine control and stop valves derived from the manufacturer's recommendations.
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Accordingly, the staff concluded that the requirements for turbine overspeed controls do not meet the TS criteria in the Final Policy Statement. The limiting conditions for operation and surveillance requirements for turbine overspeed controls were removed from the standard technical specifications.
On this basis, the staff concludes that these requirements are not required to be in the TS under 10 CFR 50.36 or Section 182a of the Atomic Energy Act, and are not required in order to provide adequate protection to the health and safety of the public. Further, they do not fall within any of the four criteria set forth in the Commission's Final Policy Statement, discussed above.
In addition, the NRC staff finds that sufficient regulatory controls exist under 10 CFR 50.59 to ensure that future changes to these requirements are acceptable. Accordingly, the staff has concluded that these requirements may be relocated from the TS to the USAR.
The NRC staff has no objection to the deletion of the Bases associated with TS 3/4.3.8.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New York State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATI@
The amendment changes 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 changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the ascunts, 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 cosseent on such finding (58 FR 64611). 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.
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 compilance 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: Donald S. Brinkman Date:
February 14. 1995
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