ML20235L129
| ML20235L129 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/17/1986 |
| From: | Gibson A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Eisenshut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20235A995 | List: |
| References | |
| NUDOCS 8902270379 | |
| Download: ML20235L129 (3) | |
Text
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?AICRITYRouting MAR 17 BBS h_, m!Eb 2
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f llhg-MEMORANDUM FOR:
Darrell G. Eisenhut, Deputy Director, Office of Nuclear Reactor Regulation FROM:
Albert F. Gibson, Director, Division of Reactor Safety
SUBJECT:
REQUEST FOR INTERPRETATION AND RESOLUTION OF TECHNICAL 1
SPECIFICATION REQUIREMENT PERTAINING TO SAFETY-RELATED PIPE SUPPORTS Duke Power Company (DPC) has recently experienced problems with safety-related pipe supports at the Catawba plant. On January 3, 1986, four damaged pipe supports were discovered on the auxiliary feedwater system while the plant was at power.
These supports were attached to the wall and ceiling using concrete expansion anchors. The anchors had pulled loose and were not supporting the piping system.
The cause of the problem was suspected to be a water hammer, and not improperly installed expansion anchors.
Since pipe hangers and restraints are not specifically addressed in Technical Specifications (TSs), the corrective action when these components are discovered damaged needs clarification.
DPC has written an interpretation based on the snubber TS for their use. The interpretation states the following:
"In order for a system to be considered OPERABLE, ALL SAFETY RELATED HANGERS / SUPPORTS / RUPTURE RESTRAINTS must be OPERABLE.
If a SAFETY RELATED hanger / support / rupture restraint becomes INOPERABLE due to damage and there is no apparent damage to the pipe or equipment.or the hanger / support / rupture restraint is removed for maintenance, then tfie associated system (s) must be declared INOPERABLE if not repaired / replaced i
J within 72-hours."
If the determination on operability cannot be made within 72-hours, the system is declared inoperable at the end of the 72-hour period and the appropriate ACTION statement for that system is followed.
In the case discussed above, DPC determined the damaged supports rendered the system inoperable from a seismic criteria only.
Repair of the damaged supports was not completed within the 72-hours. Therefore, at the end of the 72-hour action period, the auxiliary feedwater system was declared inoperable and the l
CONTACT:
J. Lenahan FTS 242-4190 l
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Darrell G. Eisenhut 2
ACTION statement for that system was followed.
This statement required the auxiliary feedwater system to be restored to OPERABLE status within 72-hours, or
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go to hot standby in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and HOT SHUTDOWN within the following six hours.
licensee was able to replace the damaged hangers within the second action period, a'nd thus, the auxiliary feedwater system was restored to OPERABLE STATUS without l
having to shut down.
l Region II inspectors questioned the validity of DPC's TS interpretation and its l
implementation.
Clarification is requested.
j l
These issues have raised two questions which are as follows:
1.
If a support is installed to resist dynamic loadings, is it permissible to use the ACTION statement of the snubber TS when the support is found to not comply with the design criteria? That is, if the support is found to be damaged, or out of tolerance (excessive gap, incorrect angle, etc.), and the piping system is not damaged does the licensee have 72-hours to evaluate to determine operability of the support system? This interpretation has been used by Region II. However, it appears to conflict with a previous inter-pretation issued by NRR, in a memorandum to C. E. Norelius, Region III, from D. G. Eisenhut, NRR dated January 29, 1985,
Subject:
Request for Interpre-tation and Resolution of Several Issues at LaSalle County Station in Connec-tion with Snubbers and Mechanical Supports. This memorandum states:
"Since a mechanical restraint is used to support a system during its normal operation, the failure of a mechanical restraint would render the supported system into an inoperable status immediately when discov-ered and the Technical Specification Action Statement for that system should be implemented at that time."
Since all mechanical restraints are not normally required to support a system during normal operation, and many are installed to resist seismic loads only, the interpretation covers only a part of the question. One difficulty is that a detailed engineering evaluation is normally to deter-i mine if a damaged support is required to support system during its normal operation. Therefore, we request reconsideration of the matter.
If it is determined that the 72-hour snubber action statement is proper, then the STS should be revised to reflect this position.
If the licensee is required to declare a system inoperable whenever a damaged seismic support is discov-ered, and enter the ACTION statement for that system, what is the purpose of the snubber action statement?
2.
Is it permissible to use the time limits imposed in two ACTION statements consecutively when the ACTION statement in one TS refers 'to another? For example, the ACTION statement for the snubbers TS states:
"With one or more snubbers inoperable, within 72-hours replace or restore the inoperable snubber (s) to OPERABLE status and perform an engineering evaluation per Specification 4.7.9.c on the supported component or declare the supported system inoperable and follow the appropriate ACTION statement for that system."
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PAR 17 1986 Darrell G. Eisenhut 3
l ACTION statements for the individual systems vary from one to 72-hours to restore system operability. The snubber TS allows 72-hours to determine operability, or correct the problem.
If this can't be accomplished, the licensee is directed to follow the appropriate ACTIONS for that affected system. This is embodied in DPC's interpretation.
Clarification on this position is requested. Note that the ACTION statements in earlier revisions of the snubber STS for both PWRs and BWRs did not refer to appropriate ACTION statements for the affected system; but, instead required inoperable snubbers to be restored to operable status within 72-hours, or, if this could not be accomplished to be at least HOT SHUTDOWN within The next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The current STS allows a variable time depending on the affected system.
In the earlier revision the times are additive.
We would appreciate an early response and would consider proposing an Infonnation Notice describing the clarification and interpretation for all licensees to j
4 ensure uniform, proper handling of damaged pipe support and restraints.
If additional information is required, please contact F. Jape (FTS 242-4182) or J.Lenahan(FTS 242-4190).
15, Albert F. Gibson cc:
S. D. Ebneter, RI
, C. Paperiello, RIII E. Johnson, RIV D. F. Kirsch, RV R. Kiessel, IE bec:
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MEMORANDUM TO:
G. C. Wright, Chief, Reactor Projects i
Section 2C l
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FROM:
M.
J.
Jordan, Senior Resident Inspector LaSalle Nuclear Station
SUBJECT:
TECHNICAL SPECIFICATIONS ON SYSTEM OPERABILITY FOR SNUBBER TESTING During the week of February 24, 1986 I became aware of a potential problem with the method the licensee was using to maintain system operability during snubber testing.
Technical Specification (T.S.) 3.7.9 states that snubbers are to be operable on systems required to be operable depending on the mode of the reactor.
The Action Statement for this Technical Specification states when one or more snubbers are inoperable within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, replace or restore inoperable snubbers to operable status and perform an engineering evaluation or declare the attached system inoperable.
The licensee was using the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Action Statement to allow him to remove and return snubbers for required operable systems to accomplish the 18 month snubber testing and was not worrying about system operability.
He felt that the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> was established as a low probabilistic time that a seismic event would happen and, therefore, removal and replacement of snubbers on required systems did not effect operability of the system until the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> were up.
I felt the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> was a reasonable time to allow the utility to l
evaluate the af f ects of finding a snubber damaged while walking through the plant bef ore having to declare a system inoperable.
Using the utility's interpretation, the utility had planned on removing snubbers from the Unit 2 common systems (hydrogen recombiners and ventilation connection to SBGT) and not worry about their ef f ect as long as they were replaced within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Unit 2 was at 100% power.
I expressed my concerns over operability of these systems with snubbers removed, and told them they should do an engineering analysis to determine how many snubbers could be removed before. operability was effected, prior to removal of any snubbers on systems that they were considering operable.
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Mr.
G.
Wright 2
2/28/86 The licensee felt that the analysis would be to costly because, depending on the mode th'e plant was in, every safety system would eventually need to be analyzed f or snubber removal.
On February 27, 1986 I contacted NRR for some assistance on what would be expected from the licensee.
NRR felt that since there are so many raubbers in the system that removal of one or two snubbers from each analyzed subsystem would be alright.
An analyzed subsystem is where an entire system (i. e.
hydrogen recombiner) is broken down into several subsystems or sections that have been seismically analyzed separately.
One or two snubber removals from each subsystem on required operational systems is the method the licensee is progressing to complete the 18 month required testing.
I have a problem with this method of testing in that during an outage in the future if the fuel is not off loaded, then several systems would be required to be operable; this is not' the case for the present Unit 1 outage.
Using the NRR interpretation, the utility could take off one or two snubbers from each analyzed subsystem for several required operational systems at the same time and not know if the systems were opera 61e or survive a seismic event.
An example would be to take one or two snubbers off each analyzed subsystem f or all ECCS Systems.
Using the present interpretation, this could be done and yet without some analysis to backup the allowed removal of the snubbers, the ECCS Systems may be inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and then in the next 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> other sets of snubbers are removed which could make the systems inoperable again and so on and so on.
I requested that NRR provide an interpretation as to what, if any, restrictions the licensee needs to do to accomplish the 18 month surveillance.
Can a utility remove one or two snubbers from a seismically analyzed subsystem from several required operation reactor systems and backup systems at the same time and not have to worry about operability criteria?
Should the utility be forced to declare systems inoperable to remove snubbers unless they have an analysis which would allow them to remove snubbers and consider the system still operable?
Why would one or two snvaber removals be acceptable?
A utility could reduce the total number of snubbers to a minimal amount and one or two removed may make the system inoperable.
I would appreciate any assistance you can provide to resolve this issue.
M.
J.
Jordan Senior Resident Inspector, LaSalle Nuclear Plant
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