ML20204B492
| ML20204B492 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/20/1987 |
| From: | Nauman D SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Chilk S NRC OFFICE OF THE SECRETARY (SECY) |
| References | |
| 86-24496, NUDOCS 8703250075 | |
| Download: ML20204B492 (8) | |
Text
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10 CFR 50 App. J.
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Mr. Samuel J. Chilk Secretary of'the Commission U.S. Nuclear Regulatory Commission Washington,DC}0555-Attn: Docke' ting and' Servicing Branch
Subject:
. Virgil C. Summer NucJear Statiori Operating License No. NPF-12 Docket No. 50-395
, Request for Comments on Proposed Revision to Appendix J, 10CFR50 Leakage Rate Testing.of Containments of Light-Water-Cooled Nuclear Power Plants FR Doc 86-24496
Dear Sir:
In the above referenced Federal Register Notice, the Commission, requested comments on the subject of Leakage Rate Testing of Containments.
This letter is being submitted in response to that request.
As members of the Atomic Industrial Forum (AIF), we have reviewed and subscribe to the comments provided by the AIF Subcommittee on Operation and Maintenance.
In addition, South Carolina Electric & Gas Company (SCE&G) would like to submit the attached comments for your consideration.
SCE&G supports the Commission's commitment to clarify the existing Appendix J.-
requirements. However, there are issues in the proposed revision to Appendix J that appear unduly burdensome.
Responses addressing the issues identified'*in i
the " Invitation to Comment" section in the subject Federal Register Notice are l
provided in Attachment I.
Included within these responses are comments regarding the broader base considerations addressed elsewhere in the subject Federal Register Notice.
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We appreciate the opportunity to comment at this time.
Should you require additional information, please contact us at your convenience.
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Mr.~ Samuel J.'Chilk March 20. 1987 Page 2
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Attachment I to Mr. Samuel J. Chilk Letter March 20, 1987 Page 1 of 6 (1)
The extent to which these positions in the proposed rule are already in use Those items generally in use at present are identified in the proposed Appendix J IIIA (1), (2), (5), (6), (9), and VA.
Many utilities are unable to use ANSI /ANS 56.8 in its entirety due to inherent conflicts'with the current Appendix J requirements.
(2)
The extent to which those in use, and those not in use but proposed, are desirable Major advantages are found in:
I a) having additional and more precise definitions, b) the reduced duration of testing, c) use of the mass point technique to compute Type A leakage rate, d) reduction of the excessive leakage isolation provisions during Type A testing, e) the provision of approved alternative leakage test program, f) airlock test extensions where no openings have occurred during a-6 month interval since last successful test, g) and the possible alternative to continue under the current requirements.
Negative aspects of the proposed Appendix J include:
a) the provision for increased local testing incurring increased downtime and radiation exposure, b) more frequent reporting as in the case of, failed Type B and C
- tests, c) more detailed and stringent requirements for reporting, i.e., to prevent recurrence (having an allowed leakage rate suggests some recurrence under normal operating conditions),
d)
The potential for changes to Technical Specifications and existing programs currently underway with possible system modifications requiring additional outage time.
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Attachment I to Mr. Samuel J. Chilk Letter March 20, 1987 Page 2 of 6 4
(3)
Whether there continues to be a further need for this regulation l
Where the stringent leaktightness of containment is required to be maintained, regulatory guidance will be needed in defining inspection programs and acceptance criteria.
The requirements should be ste.ted l
clearly and remain flexible so as to facilitate licensee compliance.
Further investigation into the need for stringent requirements should l
be continued with considerations given to NUREG/CR-4330, Vol. 2, June 1
1986:
assessments, beginning with the Reactor bfety "Probabilistic risk Study, WASH-1400 (NRC 1975), have shown that containment leakage (at, l
or slightly above the design leakage rate) is a relatively minor contributor to overall nuclear reactor risk."
l (4)
Estimates of the costs and benefits of this proposed revision, as a whole and ofits separate provisions In addition to the comments in (3) above, it would be prudent to add that, with the extensive testing and reporting requirements, and the foreseeable possibility of increased outage time and increased radiation exposure, the relevance of NUREG/CR-4330, Vol. 2 June 1986, should be considered at this time.
-1 (5)
Whether present operating plards or plants under review should be given the opportunity to continue to meet the current Appendix J provisions if the proposedrule becomes effective Licensees should have the option of continued operation under the existing program which is adequate and generally understood by licensees and contractor personnel.
No imposition of this Rule should be required without 10CFR50.109 having been addressed.
In view of NUREG/CR-4330. Vol. 2, June 1986, it would be contradictory to require implementation of the additional requirements at this time without consideration of the~Backfit Rule.
(6)
If the existing rule orits proposed revision were completely voluntary, how many licensees would adopt either version in its entirety and why It is difficult to answer this question knowing that further rev'iew of the issue has been planned.
The choice to continue a testing program-under the existing criteria cod 1d be a " locked in" situation whereby a utility may not be allowed to opt for less stringent criteria that could result from further NRC studies.
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Attachment I to Mr. Samu21 J. Chilk Letter March 20, 1987 Page 3 of 6 (7)
Whether (a) all or gart of the proposed Appendix 1 revisions would constitute a "backfit under the definition of that term in the Commissions BackRt Rule, and (b) there are parts of the rule which do not constitute backfits, but which.would aid the staff, licensees, or both Despite obvious advantages to parts of the proposed rulexa's in (2),
some of the new provisions may precip'itate individual utilities opposing the proposed rule due to the backfit nature of specific requirements involving changes to systems,
- software, Technical Specification or procedures.
(8)
Since the blRC is planning a broader, more comprehensive review of containment functional and testing requirements {p the next year or two, whether it is then still worthwhile to go forward with this prope. sed revision as an interim updating of the existing regulation Based on the need for upgraded standards, and consideration given to the issues discussed in (5) and (7), the worthiness of the proposed revision is questionable. While the need for more concise definitions and interpretations may exist, these have been accdmplished in i
publication of the proposed Appendix J, "The scope of this revision to Appendix J is limited to corrections and clarifications, and excludes new criteria."
However, additional regulatory requirements are included.
The clarification of the existing regulations could be accomplished without the additional regulatory burden.
In so much as ANSI N45-4 is outdated and new standards would be an asset to the
- program, direct reference predisposes incorporation and any endorsement of new standards should be done through a companion regulatory guide, not the Code.
However, increased conflicts between regulations and current procedures would result.
i (9)
The advisability of referencing the testing standard (ANSI /ANS 56.8)in the Regulatory Guide (MS 021-5) Instead ofin the text ofAppendix1 It.would allow more flexibility to both the NRC and the licensees to reference the testing standard in the Regulatory Guide.
This allows changes to the standard without requiring periodic revision to the regulations.
In addition, the comment is appropriate that there are i
j existing conflicts between ANSI /ANS 56.8 as well as exceptions.
For example, proposed Appendix J states that "the interval between subsequent periodic A test must not exceed four years" whereas the ANSI standard has "at intervals not to exceed five years."
The supportive statements described in (3) from NUREG/CR-4330', Vol.
2, June 1986, and the Draft Regulatory Guide (MS 021-5) which addresses the, regulatory position with respect to Type A Test Frequency as being "a. practical and logical interpretation of the end, of the test interval" indicate that five years is a considerably less burdensome interval with respect to testing frequency.
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Attachment I to Mr. Samuel J. Chilk Letter March 20, 1987 k' -
Page 4 of 6 (10)
The value of coIIecting data from the "as found" condition of valves and seals and the need for acceptance criteria for this condition
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The value of such a program would be outweighed by the disadvantages
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of additional down time.
Type B and C testing is labor-intensive and
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commands critical resources.
Preventative maintenance (PM) programs would be equal to or. better than' continually testing.
PM would identify problem areas which subsequently may require teisting and documentation for futare reference."
Data collection other than mandatory testing of com'ponents should not be a requirement.
Certain repairs and replacements incorporated in the PM program should not require pretesting, i.e., changing valves, or repairs made in which no disturbance of the seal has occurred.
(11)
Whether the technical specification limits on allowable containment leakage should be relaxed and if so, to what extent and why, or if not why not The limits on allowable leakage should be relaxed.
This has been previously indicated in reference to NUREG/CR-4330. Vol. 2, June 1986.
Recognizing the extreme conservatism entailed in the original criteria, the extent to which that criteria is relaxed should be based on valid analyses using up to date information.
(12)
What risk-Important factors influence containment performance under severe accident conditions, to what degree these factors are considered in the current containment testing requirements, and what approaches should be considered in addressing factors notpresently covered Again, reference to NUREG/CR-4330, Vol. 2, June 1986, which a'ddresses this to some extent in Section 2.0, " Risk and Cost Impact for Nuclear Reactor Containment Leaktightness."
Gross failure of containment due to rupture or failure of an isolation function appear to be the dominant risk factors.
The variety of regu4 tory coverage with respect to design, operation, inspection and testing is a broad. issue involving many technical aspects being studied throughout the industry.
(13)~
What other approaches to validating containment Integrity could be used that might provide detection of leakage paths as soon as they occur, whether the would result in any adjustments to the Appendix 1 test program an why No practical alternative exists beyond routine testing and preventative maintenance.
Continuous leakage monitoring, however unfeasible, could be a partial solution, but given that the design and operation have met the current regulatory criteria, it would be impractical to backfit.
' Attachment I to Mr. Samual J. Chilk Letter March 20, 1987 i
Page 5 of 6 (14)
What effect " Leak-before-break" assumption could have on the leakage breaks in alping systems resulting in a test program based o_ous comple test program. Current accident assumptions use instantane n pneumatic testing oV ventec, drained IInes. " Leak-before-break" assumptions presume that pipes will fail more gradually, leaking rather than Instantly emptying
" Leak-before-break" would be a le Since the risk factor of containment leak M,Js conservative approach.
te has been described as relatively minor, it would be appropriate to take a less conservative approach, which would ultimately increase the allowable limits.,
^
How to effectively adlust Type A test results to reflect individefal Type B and (15)
C test results obtained from inspections, repairs, adjustments, or replacements of penetrations and valves for the years in between Type A tests All Type B and Cperformed during same outage as a Type A test,hs) or a.
performed during a specified time period (nominally 12 mont prior to Type A test, be factored into the determination of a Type A test "as found" condition.
b.
If a particular penetration or valve falls two consecutive Type B or C tests, the frequency of testing that penetration ntust be Increased until two satisfactory B or C tests are obtained at the nominal test frequency. Attention to focus on correcting component degradation, no matter when tested, and the "as found Type A test would reflect the actualcondition of the overallcontainment boundary.
c.
Increases or decreases in Type B or C "as found" test Iesults (over the previous "as left" Type B or C test results) shall be added to or substituted from the previous "as left" Type A test result.
I.
If this sum exceeds 0.75 La but is less than 1.0 La, take measures to reduce sum to no more than 0.75 La. This is not 1,
reportable.
li.
If this sum exceeds 1.0 La, take measures to reduce sum to no more than 0.75 La. Thisis a reportable condition.
ill.
The existing requirements that the sum of all Type B and C tests be no greater than 0.6 La shallremain in effect.
l It would not be economical to schedule outages for the sole purpose of either CILRT (Type A) or LLRT (Type 8 and C).
Most probable schedules would entail LLRTs at each refueling and (unless a five year interval is granted) every other refueling for CILRTs.
It would be more appropriate to allow that current Type B and C test results be factored into Type A tests results providing that a higher leakage rateisallowedcommensuratewiththeanalysisfoundinNUREG/CR-f330, i
i Vol. 2, June 1986.
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Attachment I to Mr. Samuel J. Chilk Letter March 20, 1987 Page 6 of 6 Type B and C tests which fail criteria must be reported to the NRC within 30 days.
If Type A tests fail the criteria. reports are due ^
within 90 days.
Should Type A test failures be subjected to Type B and C test failures, reporting would be redundant. All reports should be as in the existing Appendix J, on a 90 day schedule.. Redundancy is again indicated in. Corrective Action reporting.
Relatively frequent low pressure' checks should not be considered once a plant has begun operation. Appendix J testing should be sufficient.
The trend would be to disagree with any added containment integrity verifications which exceed the present ultraconservative' requirements.
Required increased frequency of testing should be attendant only when failures are caused by the same feature.
Repairs. and corrective action followed by successful testing should preclude the increased frequency tests. The limits for Type B and C tests should be 0;75 La, as it is for Type A tests.
The same "as found" criteria should apply to Type B and C tests, i.e., if sum exceeds 1.0 1.a. reportable; if sum less than 0.75 La, extend test frequency; and if greater than 0.75 La but less than 1.0 La, repairs should be warranted Cut no reportable j
condition should exist.
l There is very little guidance in the rule for incorporating Type B and C leakage in the "as found" Type A.
The NRC requires any Type B or C j
"as.found" leakage tested up to 12 months. prior to the Type A be added to the Type A "as found."
It is possible to fail the "as found" ILRT before it is ever done if a Type C valve fails within the 12 months pFior to the Type A test.
l Adding "as found" results from B or C tests to a previous Type A "as
- left" result should not be considered unless higher leak rates are allowed.
This could cause Type-A test failures well after the fact.
Results of' any Type A test should reflect the sum of as left Type B and C results.
There is a need for further clarification of the rule for incorporating Type B.and C tests, but this should be applicable to concurrent testina.
Whether the Commission should continue its attempts to apply the Backfit Rule to all rulemaking, or whether the Rule should be revoked as it applies to rulemaking activityperse.
The Backfit Rule should not be revoked since its application to the rulemaking process is of utmost concern to the regulated community.
The Commission.should continue to apply the Backfit Rule to all rulemaking including the " substantial increase" provision.
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