ML20151Z073
| ML20151Z073 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/18/1987 |
| From: | Lewis J, Rose J, Shevlin E TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20151Z000 | List: |
| References | |
| WP-32-BFN, WP-32-BFN-R, WP-32-BFN-R00, NUDOCS 8808290156 | |
| Download: ML20151Z073 (12) | |
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(1 WELDING PROJECT EMPLOYEE CONCERN EVALUATION REPORT ADE00ACY OF STRUCTURAL SUPPORT WELDS AT BROWNS FERRY NUCLEAR PLANT PREPARED BY__
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WP-32-BFN Revision 0 WELDING EBOJECT EMPLOYEE CONCERN
SUMMARY
SHEIT ADE0VACY OF STRUCTUR$1_ SUPPORT WELDS AT BROWNS PERRY NUCLEAR PLANT I.
SCOPE OF EVALUATION This report addresses one employee concern dealing with the adequacy of structural support welds in safety related systems at Browns Ferry Nuclear Plant (BFN). Orie issue evolved from the concern.
The adequacy of many welds and hangers is questionable.
The process followed today with regard to welding and weld inspection is more detailed. Original welds would not pass current requirements.
Text of the concern is provided in the technical report (WP-32-BFN) under Attachment 1.
II ANALYSIS OF ISSUE ADDRESSED BY CONCERN The concern is factual, in that prior to the issue of Browns Ferry Standard Practice 6.2 on June 29, 1983, some structural support welds were not included in a documented quality inspection program.
Reinspection of structural supports at BFN revealed a number of deficiencies. While most of these deficiencies relate to size, length and location of welds, many of the supports also have one or more welds with rejectable discontinuities.
Analysis of the reinspection results indicates that most of the support groups are suitable for service.
It is possible that a statement of suitability for service of instrument piping supports will not be supportable without some rework.
complete details of the evaluation of this issue may be found in WP-32-BFN, paragraph III.
III. COLLECTIVE SIGNIFICANCE In that further evaluation of the support welds is necessary, the collective significance of this issue has not been determined.
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l WP-32-BFN Revision 0 IV.
R00'; CA"SE(3)
The reason for the question ra.lating to the adequacy of the support welds at Browns Ferry is that some of the weids do not meet the acceptance criteria of AWS D1.0.
These welds had not been previously identified due to the TVA decision to exclude them from the Quality Inspection Program.
V.
CORRgCTIVt ACfION It is retegnized that analysis of the id F'epection data generally supports a conclusion of suitability for secelce of support welds.
The selection of items for inspection i.as based on engineering bias rather than recognized statistical methods.
The reinspection yielded a number of rejectable weld discontinuities. Also, prior to mid 1983, some support welds were not included in a documented quality inspection program.
The results of this evaluation do.not fully support a conclus!on that the subject welds are adequate.
In order to draw such j
a conclusion, additional weld evaluation data is needed.
Action to prevent recurrence is not required, in that Standard Practice 6.2, and later Site Director Standard Practice 13.1 related welding at BEN under an inspection program. place all safety This program has been in effect since mid 1983.
VI.
REINSPECTION REQUIRED Yes.
VII. ISS'!T CLOSURE t, a.
VIII. ATTAtW4ENTS 3
Evaluation Report WP-32-BFN, Revision 0.
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WELDING PROJECT EMPLOYEE CONCERN EVLALUATION REPORT ADEOUACY OF STRUCTURAL SUPPORT WELDS AT BROWNS FERRY NUCLEAR PLANT I.
SCOPE OF EVALUATION This report addresses one employee concern.
Text of the concern is provided under Attachment 1.
The implementing procedure history for Browns Ferry Nuclear Plant (BFN) was reviewed. The BFN Phase I and draft Phase II Reports and the Weld Project draf t reports add;essing welder qualification, inspector qualification, and inspection practices wer'e reviewed. Additionally, a selection of the Phase II reinspection packages for structural supports was reviewed. The findings presented herein are based on the above noted documents and discussions with cognizant TVA Engineering, Maintenance, and Quality Assurance personnel.
II.
ISSUE ADDRESSED BY CONCERN The subject concern questions the adequacy of the support welds at BFN, and states that the original welds would not meet today's standards.
Also stated is that the process followed today with regard to welding and weld inspection is more detailed.
III. ANALYSIS OF ISSUS ADDRESSED BY CONCERNS The concern is factual, in that some of the support welds do not meet the visual acceptance criteria required by the original' installation i
specification. Whether or not this is a problem requires engineering i
evaluation. Also, relative to supports, the process (program) is now l
clearly defined, where prior to mid-1983 some support welds were not subject to the controls of tha Quality Inspection Program.
Field construction on BFN units 1 and 2 began in September 1966.
It should be noted that construction of BFN was largely completed prior to the TVA commitment to 10 CFR 50, Appendix B, in July 1972.
I l
l A review of the procedure history of BFN indicates that prior to mid-1983, quality inspection of some structural support welding was.not i
mandated by the Quality Assuranco Program. This was substantiated by discussion with several cognizant TVA personnel.
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For initial construction, an engineering decision was made that, for other than integral attachment welds to pressure boundaries, structural support welding would not be included under the Quality Inspection Program.
Rather, these supports were to be fabricated and erected in accordance with recognized national codes and standards, using design drawings and/or prudent engineering judgment Support construction was monitored on a surveillance basis by the field engineering force.
These surveillances principally considered design and lecation.
They did not specifically address quality of welding.
They were not required to'be documented.
This method of direct application of nationally recognized codes, i.e.,
AWS Dl.0-1966, combined with engineering surveillance to monitor and assess the adequacy of the installation process was ar, extension of the proven methods used in the fossil construction program.
These mathods formed the base from which the nuclear construction program evolved, and were considered adequate at the beginning of the nuclear era.
There were some attempts at proceduralizing and programmatically addressing the issue of support welds.
They were, however, limited in scope.
In January 1970, Construction Procedure BF-30, Welding Cable Tray Hangers to Structural Steel, was issued.
engineer to inspect "all welds."
This procedure required the to the attachment of the support to the structural steel.Tlie procedure, however p No instruction for performing the inspections was outlined, ar.C no acceptance criteria was given.
In November 1972, Construction Procedure BF-68 replaced BF-30.
This new procedure was limited to the attachment of cable tray supports to structural steel.
The acceptance criteria did not address size, length, or location of the welds.
Construction Procedure BF-47, Quality Assurance Program for Principal Piping Systems and Documentation, Revision 4, vas issued in September 1973.
This procedure included Standard Test No. 2, Hanger and Restraint Inspection for Piping Systems.
Standard Test No. 2 applied to the principal piping systems "that require hangers and restraints to a specific design as given by drawings and specifications."
This test required inspection for weld size only, and only for the weld which attached the support to the building steel.
In July 1974, Standard Test No. 2 was revised to include weld contour, reinforcement, and defects.
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Discussion with cognizant TVA parsonnel and essssech of design criteria indicated that many small bore piping, tubing, HVAC, and electrical supports were fabricated and erected with no detail design drawings.
Many of these systems were field-routed.
Installation requirements for hanger features were conveyed to Construction through Detailed Design Criteria for various field-routed small bore piping and tubing.
These Detailed Design Criteria documents provided the applicable design
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detalle for each feature.
This information was used by Field Engineering to perform the detailed design of the supports and determine the support spacing.
j A review of 60 Weld Project Phaso.I reinspection packages revealed that in 23 cases, a detail design drawing for the support could not be located. This observation supports the premise that the initial designs were done by Fleid Engineering personnel. Additionally, there were twelve instances where the assembly detail was shown, but insufficient or no welding details were shown.
These practices continued through construction and operation until mid-1983.
In June 1983, Standard Practice 6.2, Quality Control of Welding I
Activities, was issued.
This procedure at 2.0 states in part, "This standard practice shall apply to all welding activities at BFN."
Discussion with cognizant Maintenance and Quality Assurance personnel revealed that SP ( 2 encompassed all safety-related welding, including structural supports. SP 6.2 was superseded by Site Director Standard Practice (SDSP) 13.1, Quality Control of Welding, for all work instructions approved on or af ter November 17, 1986. The scope of SDSP 13.1 is identical to that of SP 6.2.
In that each of these standard practicos at 6.1.5 make the quality control inspections and verifications contained therein an.datory "for all CSSC and safety related permanent plant structures and components,"
it can be concluded that with the issue of Standard Practice 6.2, structural support welding for all safety-related support populatione came under the Quality Assurance Program.
Discussion with cognizant DNE (Weld Project) personnel revealed that the Welding Project Phase II reinspection of structural supports was an engineering-blased sample representative of welding performed over the life of the plant. These inspections included groups of large bore, small bore, instrument pipe and tubing supports, conduit and cable tray supports, HVAC duct supports and electrical equipment, and instrument supports.
Preliminary results of the weld reinspection indicate that the discrepancies identified were largely configurational, i.e., weld size, length, and location.
It was noted, however, that some of the supports also had rejectable discontinuities in one or more welds.
Engineering analysis of these results has thus far shown that, with the exception of instrument piping supports, the identified discrepancies are not design significant, i.e., the support wolds are suitable for service.
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The suitability for service of the instrument piping supports is being evaluated, and has not been established to date.
The Phase II reinspection treated structural welding, including supports, as one group.
of support was reinspected.As a result, only a small number of each type In that rejectable discontinuities were identified on several supports, the selection of items for inspection was not statistically based, and that prior to 1983 some support welds were not inspected under the auspices of a defined Quality Assurance program by QC Inspectors, the overall adequacy of the support welds has not been established.
In discussion with Division of Nuclear Engineering personnel, it was observed that a number of walkdown evaluations are in various stages of planning and implementation at BFN.
some degree, address structural supports.All of these walkdowns will, to Collectively, they will address each of the support groups. These programs were reviewed to determine the extent to which they.might address the quality of support welds, thus providing additional assurance that all of the welds are adequate.
Review of five of the programs and discussion with cognizant engineers revealed that these programs are intended for design reconciliation and seismic qualification of various systems.
Of approximately twenty-one walkdowns, none is planned to address welding other than weld size, length and location.
It was determined that these programs, as currently planned, do not provide the desired additional assurance that the issue raised by the employee concern is fully satisfied.
They could meet this objective with some modification.
Alternatively, other meth;ds could be developed to provide this additional assurance.
i IV.
COLLECTIVE SIGNIFICANCE i
r In that further evaluation of the support welds is necessary, the collective significance of this issue has not been determined.
V.
ROOT CAUSE(S)
The reason for the question relating to the adequacy of the support welds at Browns Ferry is that some of the welds do not meet the acceptance criteria of AWS Dl.0.
These welds'had not been previously l
identified due to the TVA decision to exclude them from the Quality Inspection program.
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VI.
CORRECTIVE ACTION It is recognized that analysis of the reinspection data generally supports a conclusion of suitability for service of support welds. The selection of items for inspection was based on engineering-bias rather than recognized statistical methods.
The reinspection yioided a number of rejectable weld discontinuities.
Also, prior to mid-1983, some support welds were not included in a documented quality inspection program.
The results of this evaluation do not fully support a conclusion that the subject welds are adequate.
In order to draw such a conclusion, additional weld evaluation data is needed.
Action to prevent recurrence is not required, in that Standard Practice 6.2, and later Site Director Standard Practice 13.1 place all safety-related welding at BFN under an inspection program.
This program has been in effect since mid-1983.
VII.
ATTACHMENTS 1.
Text of concern.
2.
Correc6ive Action Tracking Document WP-32-BFN-01.
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WELDING PROJECT EMPLOYEE CONCERN EVALUATION REPORT ATTACHMENT 1 TEXT OF EMPLOYEE CONCERNS Evaluation Report WP-32-BFN addresses one employee concern. The text of the concern is shown on the following page.
BFN-85-019-001.
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REFERENC.
- ECPS132J-ECPS132C TENNESS.
ALLEY AUTHORITY FREQUENCY
- REQUEST ONP - ISSS - RNM OFFICE br NUCLEAR POWER
- 1 EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS) k... TIME - 11:56:
CATEGORY: HE NON QA/QC HELDING EMPLOYEE CONCERN INFORMATION BY CATEGORY / SUBCATEGORY RUN DATE - 03/I4/
HP - 32 NELDS DO NOT SATISFY ACCEPTANCE CRITERIA S
H 1 REPORT APPL SUB R PLT 2 SAF RELATED HISTORICAL CONCERN REF. SECTI CONCERN NUMBER CAT CAT D LOC BF BL SQ HB REPORT ORIGIN CONCERN DESCRIPTION SUBCAT - 3.
CAT
- 1:
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BFN-85-DI9-00IO1 HE 50632 N BFN 1Y N N N NSRS DURING AN EXIT INTERVIEH THE CI EXPR 2 SS NA NA NA ESSED HIS CONCERN THAT MANY HELDS AN D HANGERS ARE QUESTIONABLE HITH RESP ECT TO THEIR ADEQUACY. THE PROCESS FOLLOWED TODAY HITH REGARD TO HELDIN G AND HELD INSPECTION IS MORE DETAIL ED AND THAT ORIGINAL HELDS IN QUESTI
'"S ON HOULD NOT PASS CURRENT REQUIREMEN
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TS.
- 1 CONCERNS FOR CATEGORY HE HP - 32 CONCERNS ARE GROUPED BY LAST 2 DIGITS OF SUBCATEGORY NUMBER.
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ECSP CORRECTIVE ACTION TRACKING DOCUMENT (CATD) l-INITIATION 1.
Imediate Corrective Action Required:
l l Yes l_X l No
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2.
Stop Work Recomended: ,l l Yes l X l No 3.
CATD No.
50132-01 r 4.
INITIATION DATE 7/17/87 5.
RESPONSIBLE ORGANIZATION: Browns Ferry 6.
PROBLEM DESCRIPTION:
l_X l QR l l NQR Additional engineering valuation of support welds at BFN is needed.
See attachment.
/ 1 / ATTACHMENTS m
7.
PROPOSED BY NAME: Ed Shevlin /
DATE:_ 7-/7-8 '/
8.
CONCURRENCE: CEC H:
DATE:
9.
APPROVAL: ECTC PROCRAM MG,R:
DATE:
CORRECTIVE ACTION 10.
PROPOSED CORRECTIVE ACTION PLAN:
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/ ATTACHMENTS 11.
PROPOSED BY: DIRECTOR /HCR:
DATE:
12.
CONCURRENCE: CEC-H:
DATE:
SRP:
DATE:
ECTC PROGRAM HCR:
DATE:
V_ERIPICATION AND CLOSEOUT 13.
Approved corrective actions have been verified as satisfactorily impicmented.
j SIGNATURE TITLE DATE 1
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, CATD 50132-01
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ATTACHMENT 1*
PROBLEM DESCRIPTION ll It is recognized that analysis of the reinspection data generally supports a conclusion of suitability for service of suppo'rt welds. The seicetion of items for inspection was based on engineering bias rather than recognized statistical methods. The reinspection yielded a number of rejectable weld discontinuities. Also, prior to mid 1983, some support welds were not included in a documented quality. inspection program.. The results of this evaluation do not fully support a conclusion that the subject welds are adequate. In order to draw such a conclusion, additional weld evaluation data is needed.
Act.lon to prevent recurrence is not required, in that Standard Practice 6.2, and later Site Director Standard Practice 13.1 place all safety related welding at BFN under an inspection program. This program has been in effect since mid 1983.
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