ML16148B131
| ML16148B131 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/03/1992 |
| From: | Wiens L Office of Nuclear Reactor Regulation |
| To: | Hampton J DUKE POWER CO. |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 TAC-M51112, TAC-M51113, TAC-M51114, NUDOCS 9204160148 | |
| Download: ML16148B131 (6) | |
Text
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.UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 April 3, 1992 Docket Nos. 50-269, 50-270 and 50-287 Mr. J. W. Hampton Vice President, Oconee Site Duke Power Company P. 0. Box 1439 Seneca, South Carolina 29679
Dear Mr. Hampton:
SUBJECT:
CONFORMANCE TO REGULATORY GUIDE 1.97 - OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 (TAC NOS. M51112/M51113/M51114)
By letter dated December 19, 1988, the staff informed Duke Power Company that the acceptability.of accumulator tank level and pressure instrumentation and its conformance to Regulatory Guide (RG) 1.97, Revision 2, remained open pending the outcome of a generic review of the environmental qualification requirements for this instrumentation. After completion of this review, the staff was to inform you of the acceptability of this issue.
The staff has completed its review and has determined that the environmental qualification requirements for the subject accumulator instrumentation can be relaxed from RG 1.97 Category 2 to Category 3 requirements enabling the use of commercial grade instruments in this application. The staff bases that finding on the fact that no operator action is based on this post-accident instrumentation and that it does not perform a safety function. The successful performance of core cooling systems can be inferred from other environmentally qualified instrumentation. In your September 28, 1984, submittal, you stated that the accumulator tank level and pressure instruments meet Category 3 requirementi. Therefore, these instruments are acceptable with respect to conforming with RG 1.97, Revision 2. A copy of the Safety Evaluation is enclosed. This completes staff action on the above TACs.
RC HLE "ETI CP 92016614j-92O4&___
PDR.
ADOCK 05000269--
F PDR
Mr. J. W. Hampton 2 -
April 3, 1992 If you have questions regarding this matter, contact me at (301) 504 1495.
Sincerely, eonard A. Wiens, Project Manager Project Directorate 11-3 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/enclosure:
See next page
Mr. J. W. Hampton Duke Power Company Oconee Nuclear Station cc:
Mr. A. V. Carr, Esquire Mr. M. E. Patrick Duke Power Company Compliance 422 South Church Street Duke Power Company Charlotte, North Carolina 28242-0001 Oconee Nuclear Site P. 0. Box 1439 J. Michael McGarry, III, Esquire Seneca, South Carolina 29679 Winston and Strawn 1400 L Street, NW.
Mr. Alan R. Herdt, Chief Washington, DC 20005 Project Branch #3 U. S. Nuclear Regulatory Commission Mr. Robert B. Borsum 101 Marietta Street, NW. Suite 2900 Babcock & Wilcox Atlanta, Georgia 30323 Nuclear Power Division Suite 525 Ms. Karen E. Long 1700 Rockville Pike Assistant Attorney General Rockville, Maryland 20852 North Carolina Department of Justice Manager, LIS P. 0. Box 629 NUS Corporation Raleigh, North Carolina 27602 2650 McCormick Drive, 3rd Floor Clearwater, Florida 34619-1035 Mr. R. L. Gill, Jr.
Licensing Senior Resident Inspector Duke Power Company U. S. Nuclear Regulatory Commission P. 0. Box 1007 Route 2, Box 610 Charlotte, North Carolina 28201-1007 Seneca, South Carolina 29678 Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, NW. Suite 2900 Atlanta, Georgia 30323 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 Office of Intergovernmental Relations 116 West Jones Street Raleigh, North Carolina 27603 County Supervisor of Oconee County Walhalla, South Carolina 29621
e
-A UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20MII ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PRESSURIZED WATER REACTORS ACCUMULATOR PRESSURE AND LEVEL INSTRUMENTATION RELAXATION OF REGULATORY GUIDE 1.97 ENVIRONMENTAL QUALIFICATION REQUIREMENTS
1.0 INTRODUCTION
Section 6.2 of the Generic Letter 82-33 requested licensees to provide a report on their implementation of Regulatory Guide (R.G.) 1.97 (Rev.2),
and methods for complying with the Commission's regulations including a supporting. technical justification of any proposed alternatives or deviations.
A review of the licensees' submittals was performed by the staff and a safety evaluation (SE) was issued for each plant. These SEs concluded that the licensees either conformed to, or adequately justified deviations from, the guidance of the Regulatory Guide for each post-accident monitoring (PAM) variable except for the variables identified in the SE.
Exceptions were identified for the accumulator level and pressure monitoring.
A large number of the exception requests were for relaxing the equipment qualification (EQ) requirement from Category 2 to Category 3 qualification that allows commercial grade instruments to be used in certain applications. However, none of the submittals requesting the exceptions provided sufficient justification for granting the exception.
These requests were denied to the licensees and applicants whose R.G. 1.97 compliance SEs were issued by the staff before 1987. Since 1987, exceptions for the accumulator instrumentation were considered by the staff as an open item till a generic resolution could be found.
Thirty-two plants requested relaxation of EQ requirements from Category 2 to Category 3 for the accumulator level and pressure instrumentation.
2.0 EVALUATION The Code of Federal Regulations 10 CFR 50.49 requires licensees to establish a program for.ualifying certain post-accident monitoring equipment for which specific guidance concerning the types of variables to be monitored is provided in revision 2 of R.G. 1.97.
This guide identifies the accumulator instrumentation as type D variable that provides information to indicate the operation of individual safety systems and other systems important to safety, to help the operator in selecting appropriate mitigating actions.
The guide lists Category 2 qualification for this instrumentation.
The Category 2 qualification criteria require the instrumentation to be qualified in accordance with R.G. 1.89 and the methodology described in NUREG-0588.
Additionally, the instrumentation with Category 2 qualification should be energized from a high-reliability power
2 source, not necessarily standby power.
In contrast to this, the Category 3 qualification criteria require only an off-site power source and the instrumentation to be only of high-quality commercial grade to withstand the specified service environment (mild environment as defined in 10 CFR 50.49, paragraph c).
Qualification criteria for instrumentation are established based on the safety function of the system whose variables are being monitored.
The selection criteria for R.G. 1.97 variables qualification category is based upon whether monitoring of system parameters is needed during and following an accident and whether subsequent operator actions in the operating procedures are dependent on the information provided by this instrumentation.
The accumulators are pressure vessels filled with borated water and pressurized with nitrogen gas.
Being a passive system, it provides a fast acting, high flow rate, cold leg injection during the injection phase of an ECCS operation.
Both volume and pressure are monitored to assure the accumulator's function in accordance with the FSAR safety analysis.
During normal operation, the accumulator is isolated from the reactor coolant system (RCS) by two check valves in series.
To prevent inadvertent closing, each accumulator's motor operated isolation valve (MOV) is normally open with its power removed, and the status of the MOV is assured by the Technical Specification surveillance requirements.
Should the RCS pressure decrease below accumulator pressure (as during a LOCA),
the check valves open and the nitrogen gas pressure will force the borated water into the RCS.
Thus, a mechanical operation of the swing-check valves is the only action required to open the injection path from the accumulator to the reactor core.
No external power source or initiating signal is needed for the accumulator to perform its safety function. The operator can only control the operation of the motor operated valve which is used to isolate the accumulator from the RCS.
Isolation from the RCS is not a safety function of the accumulator. Additionally, the accumulator is not designed to perform any post accident safety function.
The above discussion establishes that the accumulator instrumentation does not perform a safety function during or in a post-accident environment and operator actions to mitigate the effects of an accident do not depend on the information provided by the accumulator instrumentation.
Additionally, successful performance of core cooling systems can be inferred from environmentally qualified instrumentation.
3.0 CONCLUSION
Based on our review, we conclude that the post-accident monitoring of the accumulator volume and pressure does not perform a safety function and no operator action is based on the information that will require Category 2 qualification of the instrumentation.
In lieu of Category 2 qualification, Category 3 qualification of this instrumentation is acceptable.
Principal Contributor: I. Ahmed Date: March 10, 1992
Mr. J. W. Hampton 2 -
April 3, 1992 If you have questions regarding this matter, contact me at (301) 504 1495.
Sincerely,
/s/
Leonard A. Wiens, Project Manager Project Directorate 11-3 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/enclosure:
See next page DISTRIBUTION:
Docket File NRC & Local PDRs PDII-3 R/F Oconee R/F LBerry LWiens DMatthews SVarga GLainas 0GC, 15B18 LReyes, RH ACRS (10), P-315 AHansen, PDIII-3 SNewberry, 8H7 BMarcus, 8H3 LA:PDIIP P9:D4 II-3
- I-3 erry Y LWiens/cw atthews
/6%/92 q /j/92
/92 OFFICIAL RECORD COPY DOCUMENT NAME: A:RG1970NS