ML20217L883
| ML20217L883 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/21/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20217L863 | List: |
| References | |
| NUDOCS 9910270092 | |
| Download: ML20217L883 (7) | |
Text
I J
- U U'%
.p*
4 UNITED STATES
{
j NUCLEAR REGULATORY COMMISSION g
g WASHINGTON, D.C. 20555-0001 f
i
%, * * * *
- SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTf RELATED TO THE THIRD 10-YEAR INSERVICE TESTING PROGRAM RELIEF REQUESTS VERMONT YANKEE N'JCLEAR POWER STATION DOCKET NO. 50-271 l
1
1.0 INTRODUCTION
The Code of Federa/ Regulations,10 CFR 50.5Sa, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1,2, and 3 pumps and
. valves be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (the Code) and applicable addenda, except where alternatives have been authorized or relief has been requested by the licensee and granted by the Commission pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (t)(6)(i) of 10 CFR 50.55a. In proposing alternatives or requesting relief, the licensee must demonstrate that: (1) the proposed alternatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual 4
Jdifficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for its facility, Section 50.55a authorizes the Commission to approvo alternatives and to r; rant relief from ASME Code requirements upon making the necessary findings. NRC i
guideace contained in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable
!nearvice Testing Programs," provides alternatives to the Code requirements whian Ere acceptable. Further guidance is given in GL 89-04, Supplement 1, and NUREC 14&,
" Guidelines for Inservice Testing at Nuclear Power Plants.
I Title 10 of the Code of Federa/ Regulations, Section 50.55a(f)(4)(N) states in part, that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and l
l l
addenda that are incorporated by reference in paragraph (b) of that section, subject to Commission approval.
In its letter'of September 21,1999, Vermont Yankee Nuclear Power Corporation, licensee for the Vermont Yankee Nuclear Power Station, submitted two relief requests for the third 10-year interval inservice testing program for pumps and valves. The third 10-year interval began on j
September 1,1993, and ends on August 31, ?003. The program was developed in accordance with the requirements of the 1989 Edition of the ASME Code which references the ASME Code for Operations and Maintenance of Nuclear Power Plants (OM Code) Part 1, Part 6, and Part 10 (OM-1, OM-6, and OM-10), for IST of safety and relief devices, pumps, and valves.
The NRC's findings with respect to authorizing alternatives and granting or denying the IST program relief requests are given below.
9910270092 991021 PDR ADOCK 05000271 P
l 4
l e'
l l
2 l
2.0 VALVE RELIEF REQUEST l
2.1 Ralief Request RR V17, Revision 0 I
.The licensee requests relief from the testing requirements of OM-10 paragraph 4.3.2.4(c). The Code requires that each check valve be disassembled every refueling outage. The licensee proposes to disassemble and inspect, or non-intrusively test, one of the two service water j
system loop header discharge check valves every refueling outage.
2.1.1 Licensee's Basis for Requesting Relief.
I The licensee states i
Relief is requested on the basis that OMa-1988, Part 10, paragraph 4.3.2.4(c) permits 1
disassembly every refueling outage to verify operability of check valves. NUREG 1482 and Generic Letter 89-04, Position 2 permit the use of a saraple disassembly and inspection plan when the hcensee determines it is burdensome to disassemble and l
inspect all applicable valves each refueling outage. Additional ly, NUREG 1482,4.1.2 l
permits the use of non-intrusive techniques using a sample program. However, since the issuance of the NUREG recommendation, the NRC staff determined that the legal basis for approving the deviation from Code requirements may not be accomplished by j
referencing the NUREG. The deviation may only be authorized as an alternative to the regulations pursuant to 10 CFR 50.55a(a)(3)(ii) or as a specified exemption to 10 CFR 50.12.
j i
During refueling outages extensive maintenance is performed on all Service Water components in the loop scheduled to be out of service while relying on the operab!e loop j
to supply needed loads. It is burdensome to drain portions of both Service Water Loops during each refueling outage to affect component disassembly of only one valve.
1 2.1.2 Alte.rnative Testing i
The licensee proposes:
l 1
l OMa 1988, Part 10, Paragraph 4.3.2.4(c) permits disassembly every refueling outage to l
verify operabilty of check valves. NUREG 1482 and GL 89-04, Position 2 permit the use of a sample disassembly and inspection plan when the licensee determines it is l
burdensome to disassemble and inspect all applicable valves each refueling outage.
Additionally, NUREG 1482, paragraph 4.1.2 permits the use of non-intrusive techniques
{
using a sample program.
Partial flow testing of these valves is satisfied quarterly. Disassembly and inspection or l
use of non-intrusive techniques will be used to satisfy forward and reverse flow testing.
I Use of either method wi'l be performed using a sampling program during refueling outages. A sampling program is justified due to the extent of system isolation and drain-down required to perform check valve disassembly combined with the need to keep certain [ Emergency Core Cooling systems (ECCS)] and the diesel generators available during refueling outages. Regarding non-intrusive testing, NUREG 1482 specifies that l
i I
l ;,
3 j.
the extensive effort to set up test equipment and the adverse impact on system operation provide sufficient justification to defer the test to a refueling outage.
' Specifically, one check valve will be disassembled and inspected or non intrusively tested every refueling outage with the other check valve being disassembled and i
inspected or non-intrusively tested the following outage. During the disassembly, the internals of the valve will be verified to ise structurally sound (no loose or corroded parts), if the disassembled valve is not capable of achieving full stroke when exercised or there is binding or failure of the vah.aternals, the other valve will also be disassembled, inspected, and manually exercised during the same refuel [ing) outage.
Regarding non-intrusive testing, if problems are found with the sample valve that are determined to affect the operational readiness of the valve, the other valve must be tested using non-intrusive techniques during the same outage.
2.1.3 Evaluation The valves for which relief is requested, V70-43A and V70-43B, are 8-inch swing check valves l
In the service water system. These check valves have a safety function in the open direction to provide cooling water to various ECCS room area coolers during normal plant operation and to the standby einergency diesel generator jacket water, lube oil and after-coolers when the diesel generator is in service. The valves have a safety' function in the closed direction to prevent reverse flow during the service water alternate cooling mode of operation. The Code, OM 10 paragraph 4.3.2, requires that these check valves be exe cised nominally every 3 months. As an alternative to demonstrating valve obturator movement, the Code allows disassembly every i
refueling outage to determine operability of the sa!ves (OM 10 paragraph 4.3.2.4(c)). The licensee proposes to' disassemble and inspect, or non-intrusively test, one of the two valves every refueling outage. The valve to be tested will alternate every refueling outage.
l The staff's Position 2 of GL 89-04 allows for the employment of a sample disassembly and inspection plan for groups of identical v' lves in similar applications. The sample disassembly a
- and inspection plan involves grouping similar valves and testing one valve in each group during each refueling outage. Guidelines for this plan are stated in Appendix A of NUREG 1482. The j
sampling technique requires that each valve in the group be the same design and have the j
same service conditions including valve orien9 tion. Additionally, at each disassembly the licensee must verify that the disassembled va ve is capable of full-stroking and that the internals j
of the valve are structurally sound. Also, if the disassembly is to verify the full stroke capabilhy i
of the valve, the disc should be manually exercised.
A different valve of each group is required to be disassembled, inspected, and manually full-stroke exercised at each successive refueling outage, until the entire group has been tested. If
- the disassembled valve is not capable of being full-stroke exercised or there is binding or failure J
of valve internals, the remaining valves in that group must also be disassembled, inspected and l
manually full-stroke exercised during the same outage. Once this is complete, the sequence of 1
disassembly must be repeated.
)
l The 1995 ASME OM Code, paragraph ISTC 4.5.4(c) allows for a sample disassembly
~I examination program to be used to verify valve obturator movement. The sample disassembly I
..e j
l i
i 4
I examination program shall group check valves of similar design, application, and service l
condition and require a periodic examination of one valve from each group.
The licensee's proposed alternative is consistent with paragraph ISTC 4.5.4(c) and Position 2 of
)
(
s 2.1.4 - Conclusion The proposed alternative to the requirements of OM-10 paragraph 4.3.2.4(c) is approved f
pursuant to 10 CFR 50.55a(f)(4)(iv). This alternative meets the requirements of the 1995 OM
]
Code paragraph ISTC.4.5.4(c) which has been incorporated by reference into 10 CFR 50.55a (64 FR 51370).
2.2 Relief Request RR-V18, Revision 0 -
i The licensee requests relief from the testing requirements of OM-10 paragraph 4.3.2.4(c). "he Code requires that each check valve be disassembled every refueling outage. The licensee proposes to implement a sample disassembly and inspection program for 10 service water system vacuum breaker check valves.
2.2.1 Licensee's Basis for Requesting Relief The licensee states-Relief is requested on the basis that OMa-1988, paragraph 4.3.2.4(c) permits
. disassembly every refuelitig outage to verify operability of check valves. NUREG 1482 and Generic Letter 89-04, Pcsition 2 permit the use of a sample disassembly and
]
inspection plan when the licensee determines it is burdensome to disassemble and i
inspect all applicable valves each refueling outage. Additionally, NUREG 1482,4.1.2 permits the use of non-intrusive techniques using a sample program. Hc mver, since the issuance of the NUREG recommendatien, the NRC staff determined toat the legal basis for approving the deviation may only be authorized as an alternative to the regulations pursuant to 10 CFR 50.55a(a)(3)(ii) or as a specific exemption to 10 CFR 50.12.
During refueling outages axtensive maintenance is perforrrad on all Service Water components in the loop scheduled to be out of service while relying on the operable loop to supply needed loads. It is burdensome to drain portions of both Service Water Loops during each refueling outage to affect a limited amount of component disassemblies.
1 2.2.2 Alternative Testing LThe licensee proposes:
OMa-1988, Part 10, Paragraph 4.3.2.4(c) permits disassembly every refueling outage to
. verify operability of check valves. NUREG 1482 and GL 89-04, Position 2 permit the use of a sample disassembly and inspection plan when the licensee determines it is burdensome to disassemble and inspect all applicable valves each refueling outage, i
p>
i.
5.
l l
Disassembly and inspection will be used to satisfy forward and reverse flow testing.
Based on the large grouping of valve pairs and the alternating refueling outage basis for scheduling individual service water subsystem maintenance actions, disassemblies will i
be performed using a sampling program during refueling outages. Specifically, three pairs of valves (6 valves total) will be disassembled, inspected, and full-stroke exercised during one refueling outage with the other two pairs (4 valves total) being disassembled, inspected, and full-stroke exercised the following refueling outage. During the I
disassembly, the disk will be manually exercised and the internals of the valve will be l
. verified to be structurally sound (no loose or corroded parts). If a disassembled valve is j
not capable of achieving full stroke when exercised or there is binding or failure of a valve's internals, all other vacuum breaker check valves in both groups will be disassembisd, inspected, and manually full-stroke exercised during the same refueling outage. Use of non-intrusive techniques was considered for this application and determined to be impractical given the valve design and system application. Partial valve stroking with flow is not practical following reassembly. Quality disassembly, reassembly and inspection techniques provide sufficient confidence that the valves will perform their intended function when challenged.
2.2.3 Evaluation-The valves for which relief is requested are the service water system vacuum breaker check valves. These valves have a safety function in the open direction to eliminate vacuum in the service water system that is po. died to occur following a station blackout or an Appendix R fire. The valves have a safety function in the closed direction to maintain the service water j
system pressure boundary.' ihe Code, OM 10 paragraph 4.3.2, eauires that the check valves i
be exercised nominally every 3 months. As an alternative to demonstrating valve obturator movement, the Code allows disassembly cvery refueling outage to determine operability of the valves (OM-10 paragraph 4.3.2.4(c)). The licensee proposes to disassemble, inspect, and full-stroko exercise three pairs of valves (six valves total) one refueling outage with the other two pairs (four valves total) disassembled, inspected, and full-stroka exercised during the following refueling' outage.
The staff's Position 2 of GL 89-04 allows for the employment of a sample disassembly and inspection plan for groups of identical valves in similar applications. The sample disassembly and inspection plan involves grouping similar valves and testing one valve in each group during each refueling outage. The licensee proposes to disassemble, inspect, and full-stroke exercise three pairs of valves (six valves total) one refueling outage with the other two pairs (four valves total) disassembled, inspected, and full-stroke exercised during the following refueling outage.
Guidelines for this plan are stated in Appendix A of NUREG-1482. The sampling technique requires that each valve in the group be the same design and have Se same service conditions
. Including valve orientation. Additionally, at each disassembly the licensee must verify that the disassembled valve is capable of full-sttoking and that the internals of the valve are structurally sound. Also, if the disassembly is to verify the full-stroke capability of the valve, the disc should be manually exercised.
A different valve of each group is required to be disassembled, inspected, and manually full-stroke exercised at each successive refueling outage, until the entire group has been tested. Il the disassembled valve is not capable of being full-stroke exercised or there is binding or failure
I
~.,... ',
p-
[
6-t
'of valve internals, the remaining valves in that group must also be disassembled, inspected, and manually full-stroke exercised during the same outage. Once this is complete, the sequence of disassembly must be repeated.
The 1995 ASME OM Code, paragraph ISTC 4.5.4(c) allows for a sample disassembly
. examination program to be used to verify valve obturator movement. Tne sample disassembly fexamination program shall group check valves of similar design, application, and service l-condition and require a periodic examination of one valve from each group.
The licensee's proposed alternative is consistent with paragraph ISTC 4.5.4(c) and Position 2 of
~GL 89-04.
2.2.4 Conclusion -
f The proposed alternative to the requirements of OM 10 paragraph 4.3.2.4(c) is approved pursuant to 10 CFR 50.55a(f)(4)(iv). This alternative meets the requirements of the 1995 OM Code paragraph ISTC 4.5.4(c) which has been incorporated by reference into 10 CFR 50.55a
-(64 FR 51370).
3.0 ' CONCLUSION The proposed alternatives to the Code requirements described in RR-V17 and RR V18 are approved pursuant to 10 CFR 50.55a(f)(4)(iv).
Principal Contributor: M. Kotzalas Date: OctoberL21, 1999 0
l L
I
,s-1 DATED: ' October 21, 1999 SAFETY EVALUATION OF THE INSERVICE TESTING PROGRAM FOR PUMPS AND VALVES, THIRD INTERVAL PLAN, REQUEST FOR ALTERNATIVE TESTING, VERMONT YANKEE NUCLEAR POWER STATION (TAC NOS. MA6502 AND MA6503)
DISTRIBUTION Docket File PUBLIC E. Adensam(EGA1)
J. Clifford R. Croteau PDl-2 r/f T. Clark M. Kotzalas D. Terao
)
OGC G. Hill (2)
C. Anderson, RI M. Tschiltz j
]
4 l
u-
_