ML20031F104
| ML20031F104 | |
| Person / Time | |
|---|---|
| Issue date: | 02/23/1977 |
| From: | Cheng C, Shao L Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A640 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8110190189 | |
| Download: ML20031F104 (6) | |
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UNITED STATES
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NUCl. EAR REGULATORY COMMisslON WASHINGTON, D. C. 20555
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FEB 2 31977
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MEMORANDUM FOR:
Technology, D0RD. G. Eisenhut, Assistant Director fo FROM:
t.. C. Shao, Chief, Engineering Branch, DDR C. Y. Cheng, Engineering Branch, D0R
SUBJECT:
TRIP REPORT - ASME CODE COMMITTEE On January 19-20, 1977, we attended the meetings of the AstE Subgroup on Water Cool Systems and the Subcommittee on Nuc Inservice Inspection held in San Diego, California.
of areas of particular interest to the NRC are attached. Highlights Three items deserve a special attention.
position on the acce An official NRC Summer 1976 Addenda,ptability of Section XI Winter 1975 and and process pipe welds, and the hydrostatic test press Class 2 and 3 components should be established soon.
I promised to present our official positions on the first two We have issues at the next Comittee meeting here in ethesda.
. C. Shao, Chief Engineering Branch Division of Operating Reactors C. y c.c C. Y. Cheng Engineering Branch Division of Operating Reactors
Enclosures:
As Stated V. Stello Jr., D0R M. Kehnemu,yi, SD M. Hum,povs DSS W. Pota l
J. P. Knight, DSS DSS L. Frank, SD S. S. Pawlicki DSS W. F. Anderson,, SD W. Hazelton, DDR V. Seyfrit IE R. Stuart D0R G. W. Reinmuth, IE EB Members R. J. Bosnak, DSS i
J. B. Henderson, IE 110190189 910827 DR FOIA m
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ASME code Committee:
Subgroup on Water Cooled Systems (SC-XI)
Date of Meeting:
January m.
19, 1977
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NRC Staff Member:
L. C. Shao g?W Meeting Attended and Reported By:
L. C. Shao and C. Y. Cheng 1
The following areas of interest to the NRC were discussed:
1.
Proposed Revisions to the System Pressure tests and Visual Examinations Requirements for Class 1, 2 and 3 Components (ISI 76-10)
The proposed revisions amplify considerably the existing code requirements and clearly define the extent of visual examination
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required during the system pressure tests.
After extensive discussion, the latest draft was passed with one negative vote cast by the NRC representative.
Our primary concern is changes i
of the hydrostatic test pressure from 1.25 x system design pressure i
(Po) for Class 2 and from 1.1 x PD for. Class 3 to 1.1 x system pressure for which overpressure protection is provided.
This system pressure is defined as the pressure setting of safety or relief valves provided within the boundary of the system to be tested.
We believe that the proposed test pressure is too low, especially since the hydrotest is also required after repairs or replacements of a component in the system.
Although we recognize that the intent of the Sec. XI hydrotest is not the sarre as that of Sec. III, we believe that a higher test pressure n necessary at least for the required hydrotest after repairs or replacements.
posed an alternative hydrostatic test pressure of 1.25xPTherefore, th D for both Class 2 and 3 components.
This proposal was defeated.
An official NRC position should be established before the March Main Committee to resolve this issue.
i 2.
Proposed Revisions to IWA 2120 (ISI-76-35) regarding the duties of the inspector during hydrotest was also discussed and passed with some minor revisions.
However, as it stands now, there is an inconsistency in the duties of the inspector with regard to hydrotest.
The code now requires that a system leakage test be performed after repairs or replacements for Class 1 systems and a hydrostatic test be conducted for Class 2 and 3 systems.
Since the revised requirements clearly state that an inspector shall witness or otherwise verify the hydrotest and~only has to assure himself that a system leakage test has been perfonned, it results in a situation that pressure test after repairs or replacements for Class 1 systems needs not be witnessed by an inspector whereas for. Class 2 and 3 systems, it might have to be witnessed by an inspector.
This inconsistency will be referred to and resolved by the Working i
Group on Pepairs and Replacements.
3.
Inspection of Containment Penetration.and Process Pipe Welds Enclosed in Guard Pipes - The inspectability of these full I
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O. Hedden indicated that the
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conclusion from his Working Group on NDE is that because of
--J the limited diametrical clearance, the majority of these ptocess pipe welds enclosed in guard pipes are not practically inspectable in spite of an augmented volumetric inservice inspection requirements imposed by the NRC (SRP Section 3.6.2).
He also challenged the NRC position requiring the licensee to provide inspection ports in guard pipes to permit the required examination of circumferential pipe welds.
He argued whether we are com-promising the overall integrity of the guard pipe just for the sake of inspection or perhaps we dr, not really need a guard Pipe at all.
A reevaluation of this position is necessary.
The Subgroup is expecting a response from us at the next meeting.
4.
Proposed Draft of Subsection IWF Covering Component Supports (ISI-76-33) -
Draft 6 of the proposed new subsection covering inservice inspection and testing requirements for component supports (e.g. shock absorters, snubbers, etc.) was handed out for review.
Citing the recent experience in operating plants, the NRC representatives made an extensive comments on the scope of examination, exemption criteria, preservice requirements, additional examination require-ments, operability test for snubbers, etc.
A new draft will be prepared for consideration at the next Subgroup meeting.
5.
Asymmetric Reactor Vessel (RV) Loading - S. Bush brought to the Subgroup attention the recent issue concerning the effects of certain asymetric transient loads on the RV support members due to a postulated reactor coolant pipe rupture imediately adjacent to the RV.
For operating plants, since the effects of these transient loads were probably underestimated during the design stage, a re-analysis of the effects of these asymmetric loads on the vessel supports integrity for operating PWRs is necessary.
However, a detailed analysis of this problem will definitely be time consuming and expensive.
So far two PWR ownersgroups (CE this p)roblem.have been formed to look into all possible solutions to and W Westinghouse evnersgroup has proposed an alternative approach of augmented inservice inspection (doubling the existing code i
requirements) of their nonle-to-piping welds to reduce the probability of pipe rupture.
The proposed alternative solution has not been accepted by the NRC and the primary concern is the reliability of the proposed remote refracted longitudinal UT (RL-UT) examination of bi-metallic or tri-metallic welds.
In view of the difficulties experienced in the conventional shear wave UT examination of austenitic stainless steel welds, it will not be easy to demonstrate that RL-UT can reliably detect the 1
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Nevertheless, he recommended that an expanded program to further refine the proposed technique and generate more convincing data a,.....
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could reduce or eliminate the skepticism concerning the reliability o.f RL-UT. g e also advised the Subgroup that a high priority H
be placed on developing a reliable inspection technique to
' examine these welds.
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ASME Code Committee: Subconnittee on Nuclear Inservice Inspection e" -
Date of iieeting: January 20, 1977 i
NRC Staff Member:
W. F. Iederson i
Meetin~g Attended and Reporte-By:
L. C. Shao and C. Y. Cheng The following areas of interex to the NRC were discussed.
1.
Proposed Acceptance Standards for Radiographically Detennined Round Indications (ISI-76-33, Code Case 1805) - The draft code case proposes that if indications found~in welds during Sec.
XI preservice inspection can be identified as pre-existing isolated or random rounded indications as shown in Sec. III radiographs, then the Sec. III radiographic acceptance standards for porosity may be applied instead of the Sec. XI acceptance standards for planar indications. This code case previously l
received a negative ballot cast by the NRC representative at j
the last October's Main Comittee meeting and was sent back to Subcommittee for reconsideration at the last December meeting.
At tnat meeting the NRC representative proposed that the code
, case be referred to WG on Standards for review because at the same t'ime WG on Standards was considering to reinstate into the code the rules governing characterization of random, aligned or clustered porosity in welds.
This motion was defeated.
At this meeting, the NRC representative also informed the committee that we are in the process of drafting a regulatory guide to provide additional requirements for flaw characterization and we feel that the solution to this porosity problem may be the augmented inservice inspection approach.
O. Hedden indicated that prelim-inary calculations showed that most of Sec. III porosities can meet the acceptance standards for planar indications and thus the NRC objection that the rounded indication could associate I
with a crack could be acconnodated by treating the sizes of random or isolated rounded indications permitted by Sec. III as that for planar indications.
If this is true, there will be no need for such a code case.
A study of the two acceptance standards before the next meeting appears to be necessary.
2.
Proposed Revisions to Table IWB-2500. Exa ination Categories (ISI-76-46) - The proposed revisions intend to bring the extent of' examination requirements for Categor *ss B-D (Full Penetration Welds of Nozzles in Vessels) and B-F (Pressure Retaining Dissimilar Metal Welds) for Class 1 components to be in line with that for Class 2 components. The changes would limit the examination of reactor vessel full penetration nozzle welds, and dissimilar metal welds after the first inspection interval to only those nozzles that are its terminal ends of the piping runs selected for examination in Category B-J.
The examination w<
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y 2-performed during the first inspection interval shall include 100% of each nozzle-to-vessel weld and the associated dissimilar m_^^-
metal welds. The current NRC endorsed code addenda require that jg, -s.~
the examinations performed during each inspection interval shall cover the circumference of 100% of these welds. This proposal was passed by the Subconmittee with one negative vote cast by the NRC representative. The basis of our objection is similar l
to our reason of not cleanly endorsing the 1975 Winter and 1976 Sunmer addenda.
Because of the importance of these welds to the safety of the reactor, we are not sure that we can justify the further reduction in the extent of the existing cxamination
, requirements. An official NRC position concerning revisions contained in these two addenda should be established as soon as possible.
3.
Proposed Revisions of IWV-Inservice Testing of Valves (ISI-76-48) -
W. Osborne reported that because of an enormous number of valve tests required in a plant, his Subgroup is in the process of revising the scope of inservice valve testing requirements to only those valves. performing safety-related functions.
S. Bush cautioned that same isolation valves located between low and high pressure systems mAy not be performing safety functions but its failure may damage other valves performing safety-related functions. Subcommittee concurred with this proposed change l
in scope.
We recommend that the highest priority be placed on establishing a position on which valves should be inservice tested and make this position known to the committee soon.
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