ML20058L693
| ML20058L693 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/08/1993 |
| From: | Collins S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cottle W HOUSTON LIGHTING & POWER CO. |
| References | |
| TAC-M86339, NUDOCS 9312170145 | |
| Download: ML20058L693 (4) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
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AR LINGTON, TE XAS 760114064 DEC 8 1993 I
Dockets: 50-498 50-499 Licenses: NPF-76 NPF-80 Houston Lighting & Power Company ATTN: William T. Cottle, Group Vice President, Nuclear P.O. Box 289 Wadsworth, Texas 77483 l
SUBJECT:
TASK INTERFACE-AGREEMENTi INTERPRETATION OF REPORTING l
REQUIREMENTS - 93TIA006 (TAC NO. M86339)
The purpose of this. letter is to provide for your.information a copy.of the guidance recently issued by the Office of Nuclear Reactor Regulation 'in their Memorandum of November 2, 1993, to Region IV (see enclosed). This guidance was provided in response to a Region IV request for interpretation of; reporting requirements related to'aultiple failures of. safety-related i
components that are identified during the performance of surveillance. testing.-
We plan to implement this guidance during out future inspections at your _
l facilities. Should you have questions regarding this matter, pleue contact i
Tom Westerman of my staff at 817-860-8145.
l a
trector Division of Reactor Safety.
Enclosure:
(as noted) cc w/ enclosure:
Houston Lighting & Power Company i
ATIN: James J. Sheppard, General Manager Nuclear Licensing j
P.O. Box 289 Wadsworth, Texas 77483 I
i City of Austin Electric Utility Department ATIN:
J. C. Lanier/M. B. Lee 721 Barton Springs Road Austin, Texas 78704 i
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J. L. Milhoan Resident Inspector l
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RIV File Project Engineer (DRP/A)
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R. Bachmann, OGC, MS: 15-B-18 Section Chief (DRP/TSS)
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Houston' Lighting & Power Company 1 City Public Service Board ATTN:
K. J. Fiedler/M. T. Hardt P.O. Box 1771 i
San Antonio, Texas 78296 Newman & Holtzinger,.-P. C.
ATTN: Jack R. Newman, Esq.
1615 L Street, NW Washington, D.C.
20036 Central Power and Light Company 4
ATTN:
G. E. Vaughn/T. M. Puckett
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P.O. Box 2121 Corpus Christi, Texas 78403 INPO Records Center 700 Galleria Parkway Atlanta, Georgia 30339-5957 Mr. Joseph M._ Hendrie 50 Bellport La :e Be11 port, New York 11713 Bureau of Radiation Control State of Texas 1100 West 49th Street Austin, Texas 78756 Judge, Matagorda County Matagorda County Courthouse 1700 Seventh Street Bay City, Texas 77414 Licensing Representative Houston Lighting & Power Company.
Suite 610 Three Metro Center Bethesda, Maryland 20814 Houston Lighting & Power Company-ATTN: Rufus S. Scott, Associate G9neral Counsel P.O. Box 61%7 Houston, Tens 77208
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. UNITED STATES:
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NUCLEAR REGULATORY _ COMMISSION f
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November 2, 1993 MEMORANDUM FOR:
Samuel J. Collins,-Director" l
Division of Reactor Safety Region'IV.
FROM:
Elinor G. Adensam, Assistant Director '
j Division of Reactor. Projects-III/IV/V'
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j for Regions.IV and V a
Office of Nuclear Reactor Regulation
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SUBJECT:
. TASK INTERFACE AGREEMENT:' INTERPRETATION _0F REPORTING =
1 REQUIREMENTS - 93TIA006=(TAC NO. M86339)f 3
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In response to your request. dated April 13, 1993, we have reviewed the-l available guidanc6 associated with the; reporting requirements related to multiple failures of, safety-related components that: are, identified during the j
performance. of; surveillance procedures. "The; specific examples cited in:youri D
questions regarded the outage surveillances related to primary or? secondary
'l safety relief valves and the discovery that the,as-found setpoints'were:
outside the allowable technical' specification setpointqtolerances.1 Please4 note that the Public Document Room (PDR).has been included on the" distribution <
t for this response.
^
j Licensees were stated to havejpresented interpretations'.of the reporting rules, (10 CFR 50.72/50.73) and the related guidance-provided in NURFG-1022,~which H
z supported the conclusion that the discovery of safety valve setpoint drift was.
j not reportable. Specifically,. question -2.3 of NUREG-1022, L Supplement 1,:- had >
been used to argue that the condition was notireportable,. becauseithe _ _
condition could be assumed to have occurred at the time of discovery. :Anotheri-i argument presented by licensees was stated toiinvolve analyses or> evaluations-
'i which determinad that the degraded setpoints.did notiresultzin the-plant; l
operating outside its design basis..and therefore: supported a conclusionLthat' the condition was not' reportable.
A review of 50.72 and 50.73: identifies. several reporting criteria which mights be relevant to the discovery of. safety valves outside.the.setpoint; tolerances; given in the Technical Specifications. ;These criteria.and a discussion of-their applicability is_provided in Enclosure 1.
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The assessment can be. summarized.as'follows:-
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- The use of question 2.31to'NUREG-1022,. Supplement'1,--is not appropriate; L
.to justify a decision to not. report many conditions:found during:
refueling outage s'urveillances. Other g'uidance;inL Supplement.:1 is clear.
that if conditions are discovered during..'an. outage, buti are believed toi have existed tduring. operation, they_.are reportable i so' long 'as any applicable threshold for reporting;is reached.
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l Samuel J. Collins November 2, 1993
- A licensee may determine that a condition such as safety valve setpoint drift, does not constitute operation outside the design basis of the plant, and therefore not report such events in accordance with those criteria in 50.72 and 50.73.
However, as discussed below, the condition may be reportable as a result of other criteria.
- 50.73(a)(2)(vii) is deemed the most relevant criterion for the reporting of primary or secondary safety valves found to be outside the acceptable setpoint tolerance.
This is due to the fact that this criterion is based on the train or channel level and does not require the loss of a safety function but only the inoperability of multiple channels of a safety system.
Some latitude might be given in light of the number of secondary safety valves; but, for most instances of setpoint drift, this criterion would result in the conditions being reportable.
1
- Note that we currently expect to include guidance along these lines in the forthcoming Revision I to NUREG-1022; if so, that specific guidance should be consulted in the future in determining reportability.
Elinor G. Adensam, Assistant Director for Regions IV and V Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Criteria cc w/ enclosure:
W. Hodges, Region I A. Gibson, Region II G. Grant, Region III K. Perkins, Region V
ENCLOSURE ASSESSMENT OF VARIOUS REPORTINC REQUIREMENTS FOR APPLICABILITY TO PRIMARY OR SECONDARY SAFETY VAliES FOUND OUTSIDE TECHNICAL SPECIFICATION ACCEPTABLE SETPOINT TOLERANCE BAND 50.72(b)(1)(ii)
Any event or condition during operation that results in the 50.73(a)(2)(ii) condition of the nuclear power plant, including its principal safety barriers, being seriously degraded; or results in the nuclear power plant being:
(A)
In an unanalyzed condition that significantly compromises plant safety; (B)
In a condition that is outsida the design basis of the plant; or (C)
In a condition not covered by the plant's operating and emergency procedures.
Discussion:
The applicability of these criteria is determined by an evaluation of the situation by the licensee. Upon determining that the setpoints were outside the allowable range of the technical specifications, the licensee would be expected to follow the required actions of the technical specifications and assess the plant condition in regards to equipment operability and required corrective actions.
Guidance related to the evaluation of degraded and nonconforming conditions is provided by Generic Letter 91-18. As stated in the second draft of NUREG-1022, Revision 1, it is expected that licensees may use engineering judgement and experience in determining whether a condition meets these reporting criteria. The ability of a licensee to justify that a given condition is neither unanalyzed nor outside the design basis is dependent on the as-found condition of the equipment and the degree of analyses performed.
50.72(b)(2)(i)
Any event, found while the reactor is shut down, that, had it been found while the reactor was in operation, would have resulted in the nuclear power plant, including its principal safety barriers, being seriously degraded or being in an unanalyzed condition that significantly compromises plant safety.
Discussion:
The arguments are very similar to those above and again.can support either a reportable or non-reportable conclusion based on the licensee's assessment of the significance of the condition. However, this criterion was intended to capture potential problems which might be discovered only during refueling outage surveillances.
Question 7.10 in NUREG-1022, Supplement 1, is considered relevant guidance in regard to the reportability of equipment found to be inoperable during outage surveillances.
. Question 2.3 of NUREG-1022, Supplement 1, and the second draft of NUREG-1022, Revision 1, state that failures should be assumed to occur at the time of discovery unless there is firm evidence to believe otherwise.
It seems appropriate to classify setpoint drift as a mechanism which would occur some time (usually indeterminable) during the period between calibration and subsequent surveillance unless some factor, such as an extended outage or testing conditions, could be identified as a likely cause.
If testing conditions or other causes are identified such that reporting is deemed unnecessary, the licensee would still be expected, under other programs and regulatory requirements, to evaluate the adequacy of the surveillance program to ensure that the activity is ensuring the operability of the safety valves or other components.
A voluntary report may still be useful as a means of distributing the information related to the problem and its cause to the industry.
Please note that although question 2.3 may be deemed an insufficient reason to determine safety valve drift is not reportable, the licensee may determine that the significance (see above) of the condition does not satisfy the reporting threshold.
50.72(b)(2)(iii) Any event or condition that alone could have prevented the 50.73(a)(2)(v) fulfillment of a safety function of structures or systems that are needed to:
(A)
Shut down the reactor and maintain it in a safe shutdown condition, (B)
Remove residual heat, (C)
Control the release of radioactive material, or (D)
Mitigate the consequences of an accident.
Discussion:
The second draft of NUREG-1022, Revision 1, provides safety valve drift as an example of a common mode problem which may.
be reportable under this criterion. The example was added to the case described in Information Notice 85-27 which dealt with multiple inoperable control rods.
Although certain occurrences of multiple safety valve drift problems should be determined to be reportable under this criterion, it should not be assumed that all cases of one or more safety valves exceeding the technical specification tolerance band need be reportable in accordance with this criterion. As in the previously discussed reporting criteria, the licensee's engineering judgement should determine if the condition could have prevented the fulfillment of a safety function.
Candidates for reporting 1
include those cases in which the setpoints of multiple safety valves could have resulted in exceeding the associated system's design pressure.
If experience or engineering judgement can reasonably estimate the maximum
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a drift which might occur and. determine that'the safety function would.be maintained, the licensee ~can determine that the condition. is not reportable.
f Although discussed in the various drafts and revisions of.
1 NUREG-1022, it-warrants repeating that:the primary motivation behind' evaluating plant conditions such as safety""
i valve drift should be to ensure safety and only~ secondarily.
to determine reportability.
If engineering assessments identify a problem and determine _ _that plant equipment was not and reasonably could.not be rendered inoperable by.a.
phenomenon 1such as'setpoint drift, the licensee can!then
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also justify a determination that.the condition is not' i
reportable..Volunthry reports are appreciated.if the-licensee feels'the information might be helpful to others.
1 The staff should,~ as.always,- be cautious' in recommending that a licensee make a' " voluntary" report.
l 50.73(a)(2)(vi)
Events covered in paragraph (a)(2)(v) of:this section may:
include one or more procedural errors, equipment failures,;
and/or discovery of. design, analysis; fabrication, construction, and/or procedural inadequacies. !However...
U individual component failures need not be reported, pursuant to this paragraph if redundant equipment.in the-same-system j
was operable and available to' perform the required safety '
i function.
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I Discussion:
(See above) l 50.73(a)(2)(vii) Any event where a single cause or condition: caused at least i
one independent train or channel.to become' inoperable zin multiple systems or.two independentitrainsL or channels to-become inoperable in a single system designed to::
(A)
Shut down the reactor and maintain it in a safe
.j shutdown condition,
.i (B) Remove residual heat, (C) Control the release of radioactive material, or -
(D) Mitigate the consequences of an accident.
Discussion:
This criterion may be the'most relevant ~to the specific.
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example of safety valves found.outside the technical 4
specification tolerance band..As stated in the second draft ~
of HUREG-1022, Revision.1, the reporting threshold for.this?
part of 10 CFR 50.73 is lower'than for other partsisince;it:
is at the train or channel level rather than the-system and function levels. Valves found outside1the-technicali,
specification setpoint' tolerance band.can reasonably'be:
1 considered-to have been inoperable-during operation unless a -
d licensee determines that testing:is not representative of l
conditions during operation (see-item 50.72(b)(2)(1)). :Thi_s I
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criterion was developed with general consideration given to the normal two train. design level of redundancy. Given that i
most plants can satisfy pressure relief requirements with 1
j several main steam safety valves unavailable, a rigid interpretation of this criterion regarding_ the secondary
)
safety valves (i.e., any case with more than one safety valve outside the tolerance band) may be overly.
1 conservative. However, the licensees are considered to have the weakest argument if they determine that this. criterion is not applicable, and therefore the condition is not reportable, when finding multiple safety valves outside the i
acceptable range.
50.73(a)(2)(i.8) Any operation or condition prohibited by the plant's technical specifications.
Discussion:
Available guidance regarding operability and technical-specification requirements generally have licensees enter i'
the allowed outage time and associated action statements t'
i upon discovery of equipment inoperability unless a definite time of inoperability can be established. Technical:
specifications are considered satisfied provided the allowed outage time and associated action statements are satisfied.
i Therefore, provided that licensees restore compliance prior to returning to power operation, reporting of safety valve drift in accordance with this criterion would not be necessary. However, it is expected that upon identification of a problem such as. safety valve setpoint drift,' licensees should take actions to prevent recurrence or pursue a change j
in the technical specification requirements (such as j
increasing the acceptable tolerance range of the setpoints)..
4 If a licensee determines, through industry experience, infomation from a vendor, or self assessments, that a component may be inoperable during operation, appropriate actions should be taken in accordance with the technical specifications (reduce power or shutdown). This reporting criterion may be applicable if a licensee fails to satisfy the required action or can determine that a limiting i
condition of operation.had not been satisfied for. longer i
than the allowed outage time following a specific cause for a component becoming inoperable.
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