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2 Energy Technology Engineering Center k
Rocketdyne Division Rockwell international Corpo.ation Rockwell International Canoga Park, Ca orn a 9 (818)700-8200 Operated for U.S. Departrnent of Energy April 8, 1986 In reply refer to 86ETEC-DRF-0610 Mr. Vincent S. Noonan U. S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Review of Issue Specific Action Plan V.d of Comanche Peak Review Team Program Plan, Revision 3
Dear Mr. Noonan:
Enclosed are the results of ETEC's review of the subject Action Plan of Revision 3 of the Comanche Peak Review Team (CPRT) relating to unauthorized i
" plug welds" in ASME pipe supports and base plates and in AISC cable tray supports for the Comanche Peak Steam Electric Station (CPSES).
The review found that the methodology of the Action Plan V.d was generally acceptable but that the confidence level of the proposed sampling plans was less than that described in Appendix D of the Program Plan.
(The inspection technique was not fully effective). Accordingly Texas Utilities Electric Company (TUEC) is requested to modify their sampling plans and/or perform bounding analyses to achieve the Appendix D confidence level, and/or provide assurance that the ability of the pipe supports, base plates, and cable tray supports to perform their intended function has not been compromised.
Additionally, the review found that details of the proposed third party overview of TUEC engineering evaluation of uncontrolled plug welds were i adequately described.
During this review of the Action Plan, the confidence level of the sampling plans proposed by the CPRT was discussed with Dan Lurie of NRR.
It is -
anticipated that further discussions with Dan Lurie will be required to assess the confidence levels of modifications proposed in the future by the CPRT as a result of the enclosed review comments.
A preliminary draft of the enclosure was sent by Federal Express to Dr. Stou-Nien Hou on April 4, 1986. Questions related to this transmittal should be.
directed to E. G. Thompson at FTS 983-5018.
i Sincerely your.s, hNk
. W. Poucher, Programs Manager Energy Technology Engineering Center
Enclosure:
as noted c 1 };C, j '
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i Rockwell International Mr. Vincent S. Noonan U. S. Nuclear Regulatory Commission 86ETEC-DRF-0610 April 8,'1986
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cc w/o encl:
L. Shao, NRC Res Dr. S. Hou, NRC, NRR L. Ruth, NRC, NRR G. Mizuno, NRC, OELD i
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Enclosure to-86ETEC-DRF-0610 Page 1 SECTION IV-2.4 - STAFF EVALUATION OF CONSTRUCTION ADEQUACY PLAN 2.
4.1 INTRODUCTION
(Cont.)
Item V.d: Plug Welds The TRT (Technical Review Team) investigated allegations that incorrectly located bolt holes in base plates, pipe supports, and cable tray supports were " plug welded" without authorization, with undocumented weld filler metal and without Quality Control (QC)
- inspection. The TRT concluded that the repair of misdrilled holes by welding was not prohibited by the appropriate editions of the applicable Codes.
The TRT review of Brown-& Root specifications established that misdrilled holes were *egarded as' base material defects and were required to be dispositioned by Nonconformance Report (NCR) action or engineering evalution.
The TRT concluded that the identification of undocumented " plug welds" and the difficulty in detecting them raised a generic concern as to the potential existance of an unknown number of unauthorized " plug welds" of questionable quality.
Potentially. defective welds in highly stressed areas could have safety significance.
The TR7 required that the Applicant modify a plan of action already proposed to Nuclea'r Regulatory Commission (NRC) Region IV with respect to specific items or perform a bounding analysis toEassess the generic effects of undocumented " plug welds" on the ability of pipe supports, base plates and cable tray supports, to perform their intended functions.
2.4.2 CPRT APPROACH (Cont.)
Item V.d: Plug Welds Section ~4.1 of Issue Specific Action Plan (ISAP) V.d dciines the-folicwing two Comanche Peak Review Team (CPRT) Action Plan objectives:
2 1.
Confirmation of-the presence or absence of undocumented " plug welds" in American Society of Mechanical Engineers (ASME) pipe supports and base plates and assessment of the significance of any plug welds found.
2.
Assessment of the quality of cable tray supports containing' undocumented plug welds.
These objectives were to be accomplished by a combination of third party (Engineering Research Corp. FERC]) sample -inspections a.od third party overview of TVEC engineering' evaluations. The sample inspections were to be used to characterize the frequency of occurrence and location of plug welds to be j-evaluated; and the engir.eering evaluations were to be used to assess the significance of uncontrolled plug welds identified during the inspections.
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.i Enclosure to 86ETEC-DRF-0610 Page 2 Relative to the first of the above stated objectives, two random samples of ASME Code pipe supports and base plates were to be inspected. One sample was to be drawn from the Unit 1 and Common Areas population and the second from the Unit 2 population.
The use of two samples was stated to be based not on any expected difference between the two populations but on the intent to increase the inspection coverage in anticipation of a low frequency of
-occurrence of unauthorized or undocumented plug welds. Sampling was to be consistent with Appendix D of the Action Plan for a minimum sample size of 60 and a detection number of zero. However, the confidence level achievable by this sampling inspection was stated to be less than that described in Appendix D of the Action Plan (The Action Plan recognized that based on the results of test inspections of painted mockup supports containing plug welds, the inspection technique would only detect about 85% of unauthorized or undocumented plug welds. ERC field inspectors to be utilized in the s =pling inspections were to be selected based on their performance in detecting plug welds in the mockups.)
Unauthorized, plug welds identified in ASME Code pipe supports and base plates were to be identified in NCRs and engineering evaluations performed to determine the effects of these welds on the structural integrity of the affected supports and base plates.
If no undocumented plug welds were found in the samples inspected, it was proposed that it be concluded that there is. reasonable assurance that the structural integrity of the pipe supports and base plates had not been degraded by the presence of unauthorized plug welds.
Further, if all unauthorized or undocumented welds found were determined by inspection or engineering evaluation not to affect the quality of the affected pipe supports or base plates, it was proposed that the need for additional inspection be assessed based on the observed trends in the sampling inspection. However, if one or more supports or base plates were found to lack structural integrity due to unauthorized or undocumented plug welds it was proposed that the sample size be expanded, stratified sampling be utilized, or a 100% inspection be performed.
Additionally, a third party review of the existing QC inspection and documentation procedures was to be conducted and changes reccmmended as,
necessary.
With respect to the second of the above stated objectives, two random samples of cable tray supports were to be. inspected. The populations for these samples were to be similar to those for the pipe support and base plate samples.
In other respects, the steps. involved in the CPRT Action Plan to achieve this second objective pertaining to cable tray supports were to parallel those previously described relating to pipe supports and base plates.
Additionally, third party reviews were to be conducted-of: 1) Design Change Authorization (DCA) 5347 and 2) the history of the pro *grammatic procedures for QC documentation relating to plug welds. These reviews were stated to be intended to: 1) ascertain if a sufficient basis for the DCA existed at the time of issuance and 2) assess compliance of the documentation with the Quality Assurance (QA) program and Final Safety Analysis Report (FSAR) i
Enclosure to 86ETEC-DRF-0610 Page 3
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licensing commitments, respectively.
Furthermore, third party reviews of the results of the sample inspections were-to be conducted to assess the root cause and possible generic implications of unauthorized and undocumented plug welds in cable tray supports.
2.4.3 STAFF EVALUATION Based on its review of Action Plan ISAP V.d of the CPRT Program Plan relating to unauthorized and undocumented plug welds in ASME pipe supports and base plates, and American Institute of Steel Construction (AISC) cable tray supports, the staff found that the plan as currently proposed was unacceptable for the following reasons:
1.
The confidence level'of the proposed sampling plans was not in conformance with that described in Appendix D of the Program Plan.
These plans should be modified such that the achieved confidence levels are in accordance with these specified in Appendix D of the Program Plan. Justification of the confidence levels, including the effects of the lack of a fully effective inspection method for the detection of painted plug welds, will be required.
2.
If the confidence levels of Appendix D of the Program Plan cannot be achieved by sampling inspections,100% reinspection, and/or bounding analysis should be performed by Texas Utilities Electric Company (TUEC) to assess the effects of uncontrolled plug welds on the ability of either pipe supports and base plates, or cable tray supports, whichever is applicable, to serve ~their intended function.
3.
Details of the third party overview of TUEC engineering evaluations of uncontrolled plug welds identified during the sampling inspections were not provided in the Action Plan.
4.
During the March 1985 TUEC/NRC meeting to discuss the CPRT Program Plan, the TRT stated that volumetric examination of unauthorized plug welds found should be made to determine if the quality of unauthorized plug welds was the same as that of-authorized plug welds.
If differences in quality are found, assessments of these differences between unauthorized and authorized plug welds will be required..The Program Plan does not address this volumetric examination.
5.
The procedure for QC documentation of plug welds, discussed in Section 4.1.4 of ISAP V.d should be identified as Brown and Root (B&R) Procedure QI-QP-11.10-2.
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Enclosure to 86-ETEC-DRF-0610
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2.4 CONCLUSION
S Based on its evaluation of ISAP V.d of the CPRT Program Plan, the Staff concluded that the methodology of the ISAP was generally acceptable. However, the Staff found that the confidence level of the proposed sampling plans was less than that described in Appendix D-of the Program Plan.
(The inspection technique was not fully effective).
Accordingly TUEC is requested to modify their sampling plans and/or perform. bounding analyses to achieve the Appendix D' confidence level and/or provide assurance that the ability of the pipe supports, base plates, and cable tray supports to perform their intended function has not been compromised. Additionally, the review found that details of the proposed third party overview of TUEC engineering evaluation of uncontrolled plug welds were not adequately described.
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