ML20150C805
| ML20150C805 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803220322 | |
| Download: ML20150C805 (3) | |
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- o UNITED STATES E
NUCLEAR REGULATORY COMMISSION g
i W ASHINGTON, D. C. 20666 4,
,o SE000YAH NUCLEAR POWER PLANT, UNITS 1 AND 2 SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERN I
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ELEMENT REPORT 222.3(B), "DRAWINGS CO NOT ALWAYS SHOW WELD SIZE" I.
SUBJECT Category:
Engineering (20000)
Subcategory:
Pipe Support Weld Design (22200)
Element:
Crawings Do Not Always Show Weld Size (22203)
The basis for Element Report 222.3(B), Revision 1, dated December 31, 1986 is Employee Concerns EX-85-061-004 and OE-GMS-8 which state:
EX-85-061-004:
l "Drawings do not always show complete details, i.e.
specific weld size.
Construction concern. Ci has an additional detail."
OE-CMS-8:
"Two areas regarding design methods for pipe supports are not receiving proper consideration:
effect of baseplate flexibility on anchor loads; snd detailing methods for welds."
These concerns were evaluated by TVA as potentially nuclear safety-related and potentially applicable to Sequoyah (generic).
II.
SLWARY OF ISSUES The issues defined by TVA are that pipe support drawings do not always show all details, particu?arly wold sizes and welds arc not detailed properly on pin support drawings.
The effect of base plate flexibility on anchor bolt design is discusseo in construction subcategory 10400.
Ill. EVALUATION TVA personnel determined that the concerns about incompleto details and welds not being detailed properly on pipe support drawings are valid, However, an inspection of 34 supports selected by randem sanpling, showed that the installations were adequate for their intended acplications and that there are not any safety implications resultico frca these concern?.
Sequoyah Nuclear Plant has comitted to a program pian for converting to configuration control drawings to correct the problem of incomplete details on design drawings.
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. To evaluate the validity of the concerns, 34 pipe sueport drawings were selected for review. These supports were randomly selected from eleven different single phase and two phase systems and consideration was given to including different support designs such as rigid frames and snubbers.
Each support drawing was examined for welti f;mbols, bill of materials, dimensional inforration, clarity.. reference notes, and detailing methods.
TVA found 16 support drawings to be complete in every major aspect.
The other 18 support drawings had a total of 27 discrepancies which ierified the employee concerns:
l weld size missing 5
weld not specified 6
weld detail incorrect or unclear 6
drawing detail incorrect or missing 10 Sequoyah performed a physical examination of four of the supports where the weld was not specified or the weld size was missing.
In all cases a weld was found and TVA verified their adequacy by calculation.
In Phase II of the welding review program, TVA inspected welds on 50 structures at Sequoyah, and 16% of the pipe support component welds were found to have deficiencies such as drawings not specifying welds, weld size not specified, and welds nct found on structure.
These deficiencies were evaluated by TVA and accepted as adequate for the design loads.
In another inspection performed by NRC of 32 pipe supports (50-327/328/86-33),
i it was observed that some welds were not shown on drawings and in other instances, the welding information shown on the drawings was inadeouate or incorrect.
The welds in question were inspected by TVA and detcrmined to be adequate for their application.
Seouoyah concluded that there was inacequate control of the processing of field change requests and the reporting of configuration deviations.
In addition, a systematic overall configuration control program was not in place. As a result of the above report, Seouoyah comitted to a program plan to convert to configuration control drawings to correct the problem of incomplete details on design drawings.
Secuoyah also comitted to reconciling the 'as-designed' and 'as-constructed' drawings so that there l
will be a sing]e set of plant drawings.
IV. CONCLUSION i
The NRC staff believes that the TVA investigation of the concerns was adequate, and their resolution of the concerns as described in Elermnt Report 222.3(B), Revision 1 is acceptable.
TVt. has admitted that the concerns are valid in that the Sequoyah pipe support drawings do not always specify welds or show weld si:e, but physical examination of
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l supports and subsequent calculations have shown in all cases that the welds are adequate for the application.
In addition TVA has committed to a program concerning the control of drawing change requests and the reporting of configuration deviations. Further implementation of TVA comitments involving welding infotination. for supports will be monitored J
by the NRC through inspections and audits.
Contact:
P. Cortland M28734 i
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