ML020950074
| ML020950074 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 04/05/2002 |
| From: | Pickett D NRC/NRR/DLPM |
| To: | Campbell G FirstEnergy Nuclear Operating Co |
| References | |
| GL-80-030 | |
| Download: ML020950074 (7) | |
Text
April 5, 2002 Mr. Guy G. Campbell Vice President - Nuclear, Perry FirstEnergy Nuclear Operating Company P.O. Box 97, A200 Perry, OH 44081
SUBJECT:
APPLICATION OF GENERIC LETTER 80-30 GUIDANCE TO AN INOPERABLE NON-TECHNICAL SPECIFICATION SUPPORT SUBSYSTEM
Dear Mr. Campbell:
Recent discussions with your staff have focused on the performance of on-line maintenance on systems that provide a support function (i.e., a support system). Specifically, your staff has questioned how to address the single-failure design criterion for support systems that are not included in the technical specifications (TSs) that provide a support function for systems that are included in the TSs.
The staff has reviewed the guidance of Generic Letter 80-30, Clarification of the Term Operable as it Applies to Single Failure Criterion for Safety Systems Required by Technical Specifications, that allows a plant to temporarily depart from the single-failure design criterion when the plant is operating within a TS action requirement. In the enclosure, the staff has clarified the application of this guidance to non-TS support systems, and in particular to those that have two 100 percent capacity subsystems, such as Perrys ventilation system, with each subsystem capable of fully supporting both trains of TS equipment. The need for this clarification was highlighted by concerns about the conduct of on-line maintenance on Perrys ventilation system. This clarification of the existing generic guidance was developed by the TS Section of the Office of Nuclear Reactor Regulations Operating Reactor Improvement Program.
Please feel free to contact me at (301) 415-1364 if you have any questions.
Sincerely,
/RA/
Douglas V. Pickett, Senior Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-440
Enclosure:
As stated cc w/encl: See next page
ML020950074 OFFICE PM:LPD3 LA:LPD3 BC:RORP SC:LPD3 NAME DPickett THarris WBeckner* AMendiola DATE 04/05/02 04/05/02 04/02/02 04/05/02
- See 4/2/02 memo from WBeckner to SBajwa Guy G. Campbell Perry Nuclear Power Plant, Unit 1 FirstEnergy Nuclear Operating Company cc:
Mary E. OReilly FirstEnergy Corporation 76 South Main St.
Akron, OH 44308 Carol OClaire, Chief, Radiological Branch Ohio Emergency Management Agency Resident Inspectors Office 2855 West Dublin Granville Road U.S. Nuclear Regulatory Commission Columbus, OH 43235-7150 P.O. Box 331 Perry, OH 44081-0331 Mayor, Village of Perry P.O. Box 100 Regional Administrator, Region III Perry, OH 44081-0100 U.S. Nuclear Regulatory Commission 801 Warrenville Road Dennis Clum Lisle, IL 60532-4531 Radiological Assistance Section Supervisor Bureau of Radiation Protection Sue Hiatt Ohio Department of Health OCRE Interim Representative P.O. Box 118 8275 Munson Columbus, OH 43266-0118 Mentor, OH 44060 Zack. A. Clayton Gregory A. Dunn DERR Manager - Regulatory Affairs Ohio Environmental Protection Agency FirstEnergy Nuclear Operating Company ATTN: Mr. Zack A. Clayton Perry Nuclear Power Plant P.O. Box 1049 P.O. Box 97, A210 Columbus, OH 43266-0149 Perry, OH 44081 Chairman William R. Kanda, Plant Manager Perry Township Board of Trustees FirstEnergy Nuclear Operating Company 3750 Center Road, Box 65 Perry Nuclear Power Plant Perry, OH 44081 P.O. Box 97, SB306 Perry, OH 44081 Daniel Z. Fisher Transportation Department Mayor, Village of North Perry Public Utilities Commission North Perry Village Hall 180 East Broad Street 4778 Lockwood Road Columbus, OH 43215-3793 North Perry Village, OH 44081 Donna Owens, Director Ohio Department of Commerce Division of Industrial Compliance Bureau of Operations & Maintenance 6606 Tussing Road P. O. Box 4009 Reynoldsburg, OH 43068-9009
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO APPLICATION OF GENERIC LETTER 80-30 GUIDANCE TO AN INOPERABLE 100 PERCENT CAPACITY NON-TECHNICAL SPECIFICATION SUPPORT SUBSYSTEM FIRSTENERGY NUCLEAR OPERATING COMPANY PERRY NUCLEAR POWER PLANT, UNIT 1 DOCKET NO. 50-440 Technical Specifications (TSs) play an important part in the risk management of maintenance activities by limiting the duration of safety equipment outages. Because a failure to meet a systems TS limiting condition for operation usually involves a loss of redundancy, the affected system cannot withstand a single-failure and still perform its intended safety function. TSs provide a time by which the design-basis must be restored (see Generic Letter (GL) 80-30). This staff position is acceptable because, by limiting the duration of plant operation with inoperable safety equipment, the TSs manage the associated increase in risk to an acceptable level.
For plant operation with only one or two TS-required components inoperable, probabilistic risk assessment has indicated that the TS strategy for managing risk is usually conservative. But for operation with multiple TS-required components inoperable, TSs may actually allow operation that is non-conservative compared to the established risk guidelines. One reason for this is that the Nuclear Regulatory Commission never intended TSs to fully address inoperable components in several systems at the same time. Therefore, in addition to observing the limitations of TSs, licensees must also assess and manage risk associated with maintenance activities in accordance with paragraph (a)(4) of 10 CFR 50.65, the maintenance rule, which
- states, Before performing maintenance activities (including but not limited to surveillance, post-maintenance testing, and corrective and preventive maintenance), the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activities. The scope of the assessment may be limited to structures, systems, and components that a risk-informed evaluation process has shown to be significant to public health and safety.
The operability requirements for non-TS support systems are linked to the TS operability requirements of the systems they support, by the TS definition of operability:
A system, subsystem, train, component, or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified safety function(s) and when all necessary attendant instrumentation, controls, normal or ENCLOSURE
emergency electrical power, cooling and seal water, lubrication, and other auxiliary equipment that are required for the system, subsystem, train, component, or device to perform its specified safety function(s) are also capable of performing their related support function(s).
Thus, TSs also play a role in managing the risk associated with maintenance on non-TS support systems.
In most designs, the non-TS support system has two subsystems, each supporting just one TS train of safety equipment. The duration of the maintenance activity is limited by the Required Action Completion Times of the supported TS system(s). In this case, because the outage time of the non-TS support system is limited by the supported system TSs, the plant is temporarily allowed to depart from the single-failure design criterion, but the licensee may not rely solely on the TS limitations. As noted above, the licensee must still assess and manage risk in accordance with (a)(4).
In some designs, the non-TS support system has two redundant 100 percent capacity subsystems, each capable of supporting both TS trains. Loss of one support subsystem does not result in a loss of support for either train of TS equipment. Both TS trains remain operable, despite a loss of support function redundancy, because the TS definition of operability does not require a TS subsystems necessary support function to meet the single-failure design criterion.
Thus, no TS limits the duration of the non-TS support subsystem outage, even though the single-failure design requirement of the supported TS systems is not met. However, by assessing and managing risk in accordance with (a)(4), the licensee can determine an appropriate duration for the maintenance activity. Use of administrative controls to implement such a risk-informed limitation is an acceptable basis for also allowing a temporary departure from the design-basis configuration during such maintenance. Although not expected, were a licensee to determine that its risk assessment would permit the support subsystem to be inoperable for more than 90 days, then the licensee would have to evaluate the maintenance configuration as a change to the facility under 10 CFR 50.59, including consideration of the single-failure design criterion.
For the unusual non-TS support system design configuration described, the preceding is a clarification of the previous staff position (GL 80-30) regarding when a temporary departure from the single-failure design criterion is allowed. This allowance would be permitted regardless of whether the maintenance is corrective or preventive.
Regarding the situation in which the non-TS support subsystem is discovered to be in a degraded or non-conforming condition, the licensee must make a prompt determination of operability, as discussed in GL 91-18. If the non-TS support subsystem is determined to be inoperable, then the licensee must determine whether the subsystems support function is actually needed to support operability of the supported TS systems. In some situations, the licensee may be able to establish other means to temporarily provide the required support function. If the support function is required, then the risk-management strategies of the TSs and (a)(4), as described above for planned maintenance, will determine the appropriate actions and time limits to return the non-TS support subsystem to operable status, or to shut down the plant.
Principal Contributor: C Harbuck, RORP, NRR Date: