ML17264A854
| ML17264A854 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 04/09/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17264A853 | List: |
| References | |
| NUDOCS 9704110132 | |
| Download: ML17264A854 (10) | |
Text
ghee AEG0 r.
~o Cy ClO i~e
~
0 gO
++**+
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM ROCHESTER GAS AND ELECTRIC CORPORATION
.E.
GINNA NUCLEAR POWER PLANT
- 1. 0 INTRODUCTION The Code of Federal Regulations, 10 CFR 50.55a, requires that inservice testing (IST) of certain American Society of Hechanical Engineers (ASHE) Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASHE Boiler and Pressure Vessel Code (ASHE Code) and applicable
- addenda, except where relief has been requested and granted or proposed alternatives have been authorized by the Commission pursuant to 10 CFR 50.55a (f)(6)(i), (a)(3)(i), or (a)(3)(ii).
In order to obtain authorization or relief, the licensee must demonstrate that:
(1) conformance is impractical for its facility; (2) the proposed alternative provides an acceptable level of quality and safety; or (3) compliance would result in.a hardship or unusual difficultywithout a compensating increase in the level of quality'and safety.
Section 50.55a(f)(4)(iv) provides that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(b),
subject to the limitations and modifications listed, and subject to Commission approval.
NRC guidance contained in Generic Letter (GL) 89-04, "Guidance on Developing Acceptable Inservice Testing Programs,"
provided alternatives to the Code requirements
=
determined to be acceptable to the staff and authorized the use of the alternatives in Positions 1, 2, 6, 7, 9, and 10, provided the licensee follows the guidance delineated in the applicable position.
When an alternative is proposed which is in accordance with GL 89-04 guidance and is documented in the IST program, no further evaluation is required;
- however, implementation of the alternative is subject to NRC inspection.
Section 50.55a authorizes the Commission to grant relief from ASHE Code requirements o} to approve proposed alternatives upon making the necessary findings.
The NRC staff's findings with respect to granting or not granting the relief requested or authorizing the proposed alternative as part of the licensee's IST program are contained in this Safety Evaluation (SE).
In rulemaking to 10 CFR 50.55a effective September 8,
- 1992, (see 57 Federal Register 34666), the 1989 edition of ASHE Section XI was incorporated in 10 CFR 50.55a(b).
The 1989 edition provides that the rules for IST of pumps and valves shall meet the requirements set forth in ASHE Operations and Enclosure 9704fiOi32 970409 PDR ADOCK 05000244 P
Maintenance Standards Part 6 (OM-6), "Inservice Testing of Pumps in Light-Water Reactor Power Plants,"
and Part 10 (OM-10), "Inservice Testing of Valves in Light-Mater Reactor Power Plants."
Pursuant to (f)(4)(iv), portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met, and subject to Commission approval.
Because the alternatives meet later editions of the Code, relief is not required for those inservice tests that are conducted in accordance with OH-6 and OH-10, or portions thereof, provided all related requirements are met.
Whether all related requirements are met is subject to NRC inspection.
By letter dated November 14,
- 1996, Rochester Gas and Electric Company (the licensee) responded to an SE dated May 28,
- 1996, by providing additional information in support of Relief Requests VR-8 Revision 1 and VR-9 Revision 1
for the Ginna Nuclear Power Plant, third 10-year interval program for
inservice testing of valves.
The SE dated Hay 28, 1996, authorized the alternative testing proposed in the licensee's earlier submittals dated January 12,
- 1996, and March 27, 1996, for 1 year (until Hay 27, 1997).
This interim approval was to allow the licensee time to provide additional documentation to justify the proposed test interval of every three refueling outages.
Relief Requests VR-8 Revision 1 and VR-9 Revision 1,
and the ancillary information provided in the November 14,
- 1996, response are evaluated below.
The Ginna Nuclear Power Plant IST Program was developed to the 1986 Edition of ASHE Section XI, for the third 10-year interval that began January 1,
1990.
2.0 RELIEF RE UEST VR-8 REVISION 1
Relief's requested from the quarterly exercising requirements of IWV-3522 for the safety injection (SI) check valves 842A and 8428.
Relief Request VR-8 Revision 1 proposes to part-stroke exercise quarterly and full-stroke exercise once every three refueling outages.
The previous version of this relief
- request, which provided for valve disassembly instead of full-stroke exercise, was approved in an SE dated October 20, 1992.
- 2. 1 Licensee's Basis For Re uest These valves open to provide flow from the SI accumulators to the reactor coolant system (RCS).
Full-'stroke open and close exercising during normal power operation cannot be accomplished since system pressures required to perform the test are not enough to overcome RCS pressure.
A test method that permits and confirms full-stroke exercising of these check valves during cold shutdown has been developed for Ginna Station.
To perform the test, the plant must be maintained in an off-normal condition with a risk for nitrogen injection and possible entrainment in the RCS.
The performance of this test also involves added personnel radiological exposure.
Additionally, this test method requires extensive planning and setup and substantially impacts refueling outage scheduled at the start of the shutdown.
As a result of the implementation of this check valve test method, the need for periodic disassembly to satisfy Code requirements would no longer exist thereby eliminating the potential for improper reassembly.
The maintenance history of. these check valves documents that the valves have been found in excellent mechanical condition upon disassembly.
With an excellent mechanical condition baseline. verified by periodic part-stroke (quarterly) and full-stroke testing, the operability of check valves 842A and 842B will continue to be ensured.
These full-flowcheck valve tests are considered significant infrequently performed evolutions in accordance with conservative plant management directives because of the potential for adverse impact to plant operations as a result of the off-normal plant configurations required for conducting the test.
Analyses performed in preparation for these tests addressed the potential for nitrogen injection into the RCS while the residual heat removal system is in operation and for thermal shock of the SI accumulator nozzles.
Although, because of controls established for the performance of these tests, the probability for nitrogen injection into the RCS is extremely low and the thermal impact to the SI accumulator nozzles is not significant, these challenges to systems and components important to safety are not activities that the licensee believes are necessary and prudent to perform more than reasonably needed.
As stated in the basis for relief for the existing NRC-approved Relief Request VR-8 and VR-9, which employ check valve disassembly frequencies of once per 6 years, the mechanical condition of these valves has been found to be excellent when disassembled.
The successful full-flowtesting conducted during the 1995 refueling outage validated this excellent mechanical condition.
Since these valves only experience flow during testing and do not experience flow during any normal system-operational configuration, check valve degradation and wear is minimal.
Because of the system design of Ginna Station, these check valves do not function as part of the RHR system nor are they employed during RHR system operation as they are in other nuclear power plant system designs.
Licensees who test their SI check valves at a frequency less than once every three refueling outages typically employ system designs where these check valves are utilized for RCS cooling using the RHR system which subjects these check valves to significantly larger amounts of degradation and wear.
2.2 Pro osed Alternate Testin These valves will be part-stroke exercised quarterly using the SI test header.
Full-stroke exercising of 842A and 842B will be performed at a frequency of once every three refueling outages.
2.3 Evaluation Relief is requested from the 3-month frequency for the full-stroke and backflow exercising test required by ASNE Section XI, IWV-3521, which states:
"Check valves shall be exercised at least once every three months, except as provided by IWV-3522."
IWV-3522 states that valves that cannot be exercised during plant operation shall be specially identified by the owner and shall be full-stroke exercised during cold shutdown.
I The category A/C valves 842A and B open to provide a flow path from the SI accumulators to the RCS cold leg during certain accidents.
The valves are normally closed.
In the closed position, the valves function as RCS pressure isolation valves.
Full-stroke exercise testing these valves quarterly during power operations is not practicable because the accumulators are not capable of overcoming normal operating RCS pressure.
These check valves cannot be tested by discharging the accumulators into the RCS during cold shutdowns'ecause of risk associated with low-temperature overpressurization of the RCS.
For 842A and B, Relief Request VR-8 Revision 1 provides for part-stroke exercise quarterly and full-stroke exercise every three refueling outages.
This is an improvement over the testing interval proposed in relief request VR-8, which the staff approved in an SE dated October 20, 1992.
Relief Request VR-8 provided for valve disassembly at a longer interval of every 6 years.
The proposal to flow test the valves is also an improvement since the staff considers valve disassembly and inspection to be a maintenance procedure that is not equivalent to exercising produced by fluid flow.
The licensee states that, to perform the test, the plant must be maintained in an off-normal condition with a risk for thermal shock of the accumulator nozzles and for nitrogen injection and possible entrainment in the RCS and that the performance of this test also involves added personnel radiological exposure.
The licensee indicates that this test method requires extensive planning and setup and substantially impacts the refueling outage schedule at the start of the shutdown.
- Further, the licensee states that these valves have only experienced flow during testing such that degradation and wear are minimal.
The mechanical condition of the valves was found to be excellent when disassembled as part of. the commitment made in the previous version of this relief request.
The mechanical condition of the valves'nternals has been found to be excellent after 20 years of operation because these valves experience minimal use and are not subject to significant amount of degradation or wear.
- Further, the full-stroke exercising every three refueling outages proposed in VR-8 Revision 1 is an improvement over valve disassembly every 6 years (specified in VR-8) that had been approved by the staff.
Therefore, VR-8 Revision 1 is authorized based on a finding that the proposed alternative provides an acceptable level of quality and safety.
2.4 Conclusion The proposed alternative is authorized pursuant to Section 50.55a(a)(3)(i),
based on the determination that the proposal provides an acceptable level of quality and safety.
3.0 RELIEF RE VEST VR-9 REVISION 1
Relief is requested from the quarterly exercising requirements of IMV-3522 for the SI check valves 867A and 867B.
Relief request VR-9 Revision 1 proposes to part-stroke exercise each refueling outage and full-stroke exercise once every If
three refueling outages.
The previous version of this relief request, which provided for valve disassembly instead of full-stroke exercise, was approved in an SE dated October 20, 1992.
- 3. 1 Licensee's Basis For Re uest These valves open to provide a flowpath from the SI accumulators or the SI pumps to the RCS cold legs.
Full-stroke or part-stroke open and close exercising during normal power operation cannot be accomplished since system pressures available to perform the test are not enough to overcome RCS pressure.
A test method that permits and confirms full-stroke exercising of these check valves during cold shutdown has been developed for Ginna Station.
To perform the'test, the plant must be maintained in an off-normal condition with a risk for nitrogen injection and possible entrainment in the RCS.
The performance of this test also involves
'dded personnel radiological exposure.
Additionally, this test method requires extensive planning and setup and substantially impacts the refueling outage schedule at the start of the shutdown.
As a result of the implementation of this check valve test method, the need for periodic disassembly to satisfy the Code requirements would no longer exist, thereby eliminating the potential for improper reassembly.
The maintenance history of these check valves documents that these valves are found in excellent mechanical condition upon disassembly.
With an excellent mechanical condition baseline verified by periodic part-stroke and full-stroke
- testing, the operability,of check valves 867A and 867B will continue to be ensured.
These full-flowcheck valve tests are considered significant infrequently performed evolutions in accordance with conservative plant management directives because of the potential for adverse impact to plant operations as a result of the off-normal plant configurations required for conducting the test.
Analyses performed in preparation for these tests addressed the potential for nitrogen injection into the RCS while the residual'heat removal system is in operation and for thermal shock of the SI accumulator nozzles.
Although, because of controls established for the performance of these tests, the probability for nitrogen injection into the RCS is extremely low and the thermal impact to the SI accumulator nozzles is not significant, these challenges to systems and components important to safety are not activities that the licensee believes are necessary and prudent to perform more than reasonably needed.
As stated in the basis for relief for the existing NRC approved Relief Request VR-8 and VR-9, which employ check valve disassembly frequencies of once per 6 years, the'echanical condition of these valves has been found to be excellent when disassembled.
The successful full-flowtesting conducted during the 1995 refueling outage validated this excellent mechanical condition.
Since these valves only experience flow during testing and do not experience flow during any normal system-operational configuration, check valve degradation and w'ear.is minimal.
J IP 1 ~
P I
Because of the system design of Ginna Station, these check valves do not function as part of the'HR system nor are they employed during RHR system operation as they are in other nuclear power plant system designs.
Licensees who test their SI check valves at a frequency less than once every three refueling outages typically employ system designs where these check valves are utilized for RCS cooling using the RHR system which subjects these check valves to significantly larger amounts of degradation and wear.
3.2 Pro osed Alternate Testin These valves will be part-stroke exercised each refueling outage using actual SI flow into the RCS.
Full-stroke exercising of 867A and 867B will be performed at a frequency of once every three refueling outages.
3.3 Evaluation Relief is requested from the 3-month frequency for the full-stroke and backflow exercising test required by ASHE Section XI, IWV-3521, which states:
"Check valves shall be exercised at least once every three months, except as provided by IWV-3522."
IWV-3522 states that valves that cannot be exercised during plant 'operation shall be specially identified by the owner and shall be full-stroke exercised during cold shutdown.
The category A/C valves 867A and B open to provide a flow path from the SI accumulators or 'the SI pumps to the RCS cold leg during 'certain accidents.,
The valves are normally closed.
In the closed position, the valves function as RCS pressure isolation valves.
Full or part-stroke exercising these valves quarterly during power operation is not practicable because, the accumulators or the SI pumps are not capable of overcoming normal operating RCS pressure.
These check valves cannot be full-or part-stroke exercise tested by establishing SI pump flow and/or discharging the accumulators into the 'RCS during cold shutdowns because of risk associated with low-temperature overpressurization of the RCS.
For 867A and B, Relief Request VR-9 Revision I provides for part-stroke exercise quarterly and full-stroke exercise every three refueling outages.
This is an improvement. over the testing interval proposed in Relief Request VR-9, which the staff approved in an SE dated October 20, 1992.
Relief Request VR-9 provided for valve disassembly at a longer interval of every 6 years.
The proposal to flow test the valves is also an improvement since the staff considers valve disassembly and inspection to be a maintenance procedure that is not equivalent to exercising produced by fluid flow.
The licensee states that, to perform the test, the plant must be maintained in an off-normal condition with a risk for thermal shock of the accumulator nozzles and for nitrogen injection and possible entrainment in the RCS and that the performance of this test also involves added personnel radiological exposure.
The licensee indicates that this test method requires extensive planning and setup and substantially impacts the refueling outage schedule at the start of the shutdown.
- Further, the licensee states that these valves have only experienced flow du> ing testing such that degradation and wear are
minimal.
The mechanical condition of the valves was found to be excellent when disassembled as part of, the commitment made in the previously approved Relief Request VR-9.
The mechanical condition of the valves'nternals has been found to be excellent after 20 years of operation because these valves experience minimal use and are not subject to significant amount of degradation or wear.
- Further, the full-stroke exercising every three refueling outages proposed in VR-9 Revision 1 is an improvement over valve disassembly every
-6 years (specified in VR-9) that had been approved by the staff.
Therefore, VR-9 Revision 1 is authorized based on a finding that the proposed alternative provides an acceptable level of quality and safety.
3.4 Conclusion The proposed alternative is authorized pursuant to Section 50.55a(a)(3)(i),
based on the determination that the proposal provides an acceptable level of quality and safety.
4.0 CONCLUSION
The proposed alternatives in Relief Requests VR-8 Revision 1 and VR-9 Revision 1 are authorized pursuant to Section 50.55a(a)(3)(i),
based on, the determination that the proposals provide an acceptable level of quality and safety.-
Principal Contributor:
K. Dempsey Date:
April 9, 1997
a 4 ~l A
\\