ML20198F026
| ML20198F026 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 08/06/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198F023 | List: |
| References | |
| NUDOCS 9708110149 | |
| Download: ML20198F026 (6) | |
Text
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pW4 g
t UNITED STATES g
j NUCLEAR REGULATORY COMMISSION t
WASHINGTON D.C. 30eeHo01 l
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.176 AND 180 TO FACILITY OPERATING LICENSE NOS. OPR-24 AND DPR 27 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT. UNIT NOS. 1 AND 2 DOCKET NOS. 50-266 AND 50-301
1.0 INTRODUCTION
By letter dated February 12, 1997, as su 11, 1997, the Wisconsin Electric Power Company (WEPCO.pplemented March the licensee) requested amendments to the Technical Specifications (TSs) a) pended to Facility Operating License Nos.
DPR-24 and DPR-27 for the Point Beac1 Nuclear Plant (PBNP) Unit Nos. 1 and 2.
The proposed amendments would relocate turbine overspeed protection specifications. limiting conditions for operation, surveillance requirements, and associated bases from TS Section 15.3.4. "Steani and Power Conversion System " and Section 15.4.1
" Operational Safety Review." to the Final Safety Analysis Report (FSAR). These changes are in accordance with Generic Letter (GL) 95-10. " Relocation of Selected Technical Specification Requirements Related to Instrumentation." and are consistent with NUREG-1431. " Standard Technical Specifications Westinghouse Plants." Revision 1.
2.0 EVALUATION 2.1 Prooosed Chances The licensee proposes to relocate the following specifications, limiting conditions for operation, surveillance requirements. and associated bases for the turbine overspeed system from the TSs to the FSAR:
1.
TS 15.3.4.E - The cressover steam dump system shall be operable. If the crossover steam dump system is determined to be inoperable, reduce power to less than 480 MWe (gross) within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
The licensee has evaluated a change to reduce the power level from 480 MWe to 437 MWe per the requirements of 10 CFR 50.59 in PBNP SER 95-058-01. The revised limit will be included in the relocation of this specification to the FSAR.
2.
TS 15.3.4.E Basis - The crossover steam dump system is designed to prevent the turbine from exceeding 132% of rated speed following a unit trip. The system is armed at approximately 430 MWe. The system receives input from, and is actuated when the turbine auxiliary governor and/or the Independent Overspeed Protection System (IOPS) senses an overspeed NO"kDNk N000266 p
"j condition. The system consists of four pilot-operated dump valves. with only three valves being necessary to achieve the required overspeed
-protection.
However in order to meet single failure criteria. the crossover steam dump system shall be declared inoperable if any one of the four dump valves is declared inoperable.
3.
TS 15.3.4.F - During power operation, at least one of the turbine overspeed protection systems that trip the turbine stop valves or shW the turbine governor valves shall be o)erable.
If all three syster-ae determined to be ino)erable. 1solate tie turbine from the steam su,,.y within the next six lours.
4.
TS 15.3.4.F Basis - In addition to the crossover steam dump system, there are three other systems that protect the turbine from an overspeed condition.
The first feature is the mechanical overspeed trip mechanism
-which consists of an eccentric weight located in the turbine rotor extension shaft. The second feature uses the turbine auxiliary governor to sense turbine overspeed using the auxiliary speed tachometer. The third feature is 10PS. This system monitors turbine speed electrically l
and consists of three independent speed channels. The actuation of two of three channels will generate a tri) signal. The mechanical overspeed tri mechanism and 10PS cause the tur)ine stop valves to trip and the 4
tur ine governor valves to shut, while the auxiliary governor causes only the governor valves to shut. A turbine stop valve shall-be declared inoperable if it does not trip shut following a valid overspeed signal. A turbine governor valve shall be declared inoperable if it does not respond properly following a valid overspeed signal.
5.
TS 15.3.4.G - Should one of the turbine sto) valves or governor valves be declared inoperable, restore the inoperaale valve to an operable status within 72. hours.
If operability cannot be restored. perform one of the following actions:
- 1. Shut the affected valve within the next-six hours: 2. Isolate the turbine from the steam supply within the next six hours.
6.
TS Table 15.4.1-1.-Item 42. Calibration (refueling frequency) and test (monthly frequency) for turbine overspeed trip.
7.
TS Table 15.4.1-2. Item 18 - Turbine stop and governor valves annual test.
8.
TS Table 15.4.1-2. Item 19 - Low pressure turbine rotor five-year v4sual and magnetic particle or liquid penetrant inspection, 9.
TS Table 15.4.1-2. Item 29 - Crossover steam dump _ system quarterly steam dump valve operability verification.
2.2 Backaround Section 182a of the Atomic Energy Act (the "Act") requires applicants-for nuclear power plant operating licenses to include TSs. part of the license.
The Commission's regulatory requirements related to the content of TSs are set
3-forth in 10 CFR 50.36. That regulation re five specific categories including (1) sahuires that the TSs include items in ety limits, limiting safety system settings, and limiting control settings: (2) limiting coaditions for operation: (3) surveillance reauirements: (4) design features: and (5) administrative controls. However, the regulation does not specify the particular requirements to be included in a plant's TSs.
l l
The Comission has provided guidance for the contents of TSs in its " Final Policy Statement on Technical Specifications Im Reactors" (" Final Policy Statement") (July 22. provements for Nuclear Power 1993. 58 FR 391 Comission indicated that compliance with the Final Policy Statement satisfies Section 182a of the Act.
In particular, the Comission indicated that certain items could be relocated from the TSs to licensee-controlled documents, consistent with the standard enunciated in Portland General Electrfc 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 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 imediate threat to the public health and safety." The criteria set forth in the policy statement have been incorporated into 10 CFR 50.36 (60 FR 36953):
The regulations in 10 CFR 50.36. as amended identify four criteria to be used in determining whether a particular matter is required to be included in the TS, as follows:
1.
Installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary:
2 a process variable, design feature, or operating restriction that is an initial 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 mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and 4.
a structure, system, or component which operating experience or 3robabilistic safety assessment has shown to be significant to public lealth and safety.1 In amending 10 CFR 50.36, the Commission indicated that reactor core isolation cooling isolation condenser, residual heat removal, standby liquid control, and recirculation pump trip systems are included in the TSs under Criterion 4. although it recognized that other structures, systems, and components could also meet this criterion.
4-As a result, existing TS requirements that fall within or satisfy any of the criteria in this regulation must be retained in the TSs while those TS requirements that do not fall within or satisfy these criteria may be relocated to other, licensee controlled documents.
The Commission's Final Policy Statement and documentation related to the l
revision of 10 CFR 50.36 acknowledged that implementation of these criteria may cause some requirements presently in TSs to be moved out of existing TSs to documents and programs controlled by licensees.
The staff evaluation for removal of turbine overspeed protection requirements from the TSs is included in GL 95 10.
This generic letter addresses the relocation of selected TS requirements related to instrumentation to certain licensee-controlled documents as a result of applying the 10 CFR 50.36 criteria. The staff also concluded that the instrumentation addressed by these specifications are not related to dominant contributors to plant risk.
2.3 Relocation of Turbine Oversoeed Protection from the TSs PBNP TSs include limiting conditions for operation and surveillance requirements for the turbine overspeed protection system. The turbine is equipped with control valves and stop valves that control turbine speed during normal plant operation and )rotect it from overspeed during abnormal conditions.
In addition, P3NP has a crossover steam dump system designed to prevent the turbine from exceeding 132 percent of rated speed following a unit trip. The crossover steam dump system receives input from, and is actuated when, the turbine auxiliary governor and/or the Independent Overspeed System (10PS) senses an overspeed condition. The PBNP turbine overspeed protection system consists of separate mechanical and electrical sensing mechanisms that are capable of initiating fast closure of the control and stop valves.
Current PBNP TSs require particular operability and surveillance requirements for the steam control valves, stop valves, and crossover steam dump system to minimize the potential for fragment missiles generated by a turbine overspeed event. General Design Criterion 4 of Appendix A to 10 CFR Part 50 requires that structures, systems, and components important to safety be appropriately protected from the effects of missiles that may result from equipment failures. Application of the design criterion to turbine missiles is described in Standard Review Plan Section 10.2 and in subsequent safety evaluations related to probabilities of turbine failures, turbine orientations, and surveillance requirements for turbine overspeed protection systems.
In NUREG-1366 "Im3rovements to Technical Specifications Surveillance Requirement." t1e staff discusses the benefits, resultant costs, and the safety impact of performing turbine overspeed protection surveillances.
Although the design-basis accidents and transients include a variety of system failures and conditions that might result from turbine overspeed events and potential missiles striking various plant systems and equipment. 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 the 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.
v Probabilistic safety assessments and operating experience have demonstrated that proper maintenance of the turbine overspeed control valves is important to minimize the )otential for overspeed events and turbine damage: however, that experience las 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 b;' factors such as the orientation of the turbine relative to plant structures and equi) ment, licensee inservice testing programs. which must comply with 10 C:R 50.55(a), and surveillance prograins for the turbine control and stop valves derived from the manufacturer s recommendations.
2.4.
Summary Accordingly, the staff concludes that the turbine overspeed protection system, including the crossover steam dump system and the requirement to periodically perform visual and magnetic particle or liquid penetrant examination of the low pressure turbine rotor, does not meet the 10 CFR 50.36 criteria.
The licensee has committed to relocate the TSs as described in Section 2.1 of this safety evaluation to the FSAR and control changes to these provisions in accordance with 10 CFR 50.59.
On this basis, the staff concludes that these requirements are not required to be in the TSs under 10 CFR 50,36 or Section 182a of the Atomic Energy Act, and are not required in order to-provide adecuate protection to the health and safety of the public.
In addition, the hRC 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 TSs to the FSAR.
The NRC staff has no objection to the deletion of the Bases associated with TS 15.3.4.E. and F.
q
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Wisconsin State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDEPATION These amendments change requirements with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of_ any effluent that may be released offsite, and that there is no significant increase in individual or cumulative occupa-tional radiation exposure. The Commission has previously published a proposed
, finding that these amendments involve no 'significant hazards consideration and there has been no public comment on such finding (62 FR 19838). Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental inpact statement or environmental assessment need be prepared in connection with the issuance of these 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:
Linda L. Gundrum Date: August 6, 1997
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