IR 05000275/1982039
| ML20028C871 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/30/1982 |
| From: | Burdoin J, Elin J, Zwetzig G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML20028C863 | List: |
| References | |
| 50-275-82-39, 50-323-82-17, NUDOCS 8301140250 | |
| Download: ML20028C871 (6) | |
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U. S., NUCLEAR FIGUIATORY CCh!MISSIO;I
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REGION V
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' Report No.
50-275/82-39 50-323/82-17 Docket No.
50-275, 50-323 License No.
DPR-76. CPPR-69. Safeguards Group Licensee:
Pacific Gas and Electric Company P. O. Box 7442 San Francisco, California 94120 Facility Na=e: Diablo Canyon Units 1 and 2
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Inspection at: Diablo Canyon Site, San Luis Obispo County, California Inspection condtete.
November 29,through December 17, 1982 12.lJeffz'
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Inspectors:
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Ek, ~ Reactor Inspector Date Signed n/30/sw J.(/Elin, Reactor Inspector Ddte Signed
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Date Signed Ap' roved by f-/2.
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p N1'tlT,"Criief{ Engineering Programs Section date S4gned
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Date Signed
,,. Summary:
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Inspections during period of November 29 - December 17, 1982 (Report Nos. 50-275/82-39 and 50-323/82-17)
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Areas Inspected: Announced inspections by regional based inspectors of construction and modification activities including: a site tour; licensee actions on previously identified items; modifications to annulus structural steel, and electrical raceway and pipe supports resulting from the verification
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program; and QC surveillances of onsite contractors.
The inspection involved 49 inspection hours by two inspectors.
Results: No items of noncompliance or deviations were identified.
83d1140250 821230 PDR ADOCK 05000275 G
PDR RV Form 219 (2)
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2.
Site Tour A-tour was made of the Unit 2 auxiliary ' building and containment.
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- The post LOCA sampling cabinet located in the penetration area was found to have" thick' deposits of dust on terminal blocks and other equipment located in the cabi' net. This condition was identified to
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' the licensee. _The licensee had cleaned the panel and area prior to the completion of-the inspection.
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V Equipment areas inspected in the auxiliary ~ building were: RHR pump
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rooms, charging pump rooms, component cooling wat'er pump rooms,
= containment spray pump rooms, safety injection pump. rooms, and the auxiliary feedwater. pump rooms.
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Areas inspected in-the containment included reactor coolant pump 2-2 and the containment. sump.
No items'of noncompliance or deviations were identified.
3.
Licensee Actions on Previously Identified Item.
e (Closed) Unresolved Item (50-323/82-13/01):
Rupture-Restraint Weldments, Unit 2
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a.
Item of Concern The licensee had previously accepted weld reinforcement in excess of that allowed ~ by the AWS Code and by Pullman specifica-tion ESD-243 for welds on the Unit 2 main feedwater pipe rupture restraints _.
The following eight full penetration welds were involved: FW-36, FW-37, FW-38,' FW-39, FW-40A, FW-40B, FW-43A, and FW443B.
The rupture restraint structure'is made up of a 1-1/2" thick steel plate which spans the space between the two 2-7/16" thick flanges on a column. The weldments in question are single bevel type where the 1-1/2" plate " TEES" into the 2-7/16" flang-The excess weld reinforcement ranges from.1/32" to 1/8" aoove.the 1/8" reinforcement allowed by the AWS Code.
b.
Background Excess _ weld reinforcement may cause excessive stress concentra-tions~at the junction of the base metal and weld metal due to the abrupt change of direction of the surfaces involved (i.e.,
the steep contact angle of the reinforcement with respect to the surface of the base material).
Fatigue cracking is frequently associated with stress concentrations. The practice of grinding off excess reinforcement without altering the contact angle does not reduce the stress concentrations.
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c.
Justification The licensee's justification for accepting the excess weld reinforcements is as follows:
The 1979 edition of the "American Welding Society Structural Welding Code-Steel" (AWS D1.1) is being used as the fabrication code for the repair of rupture restraints at the Diablo Canyon Power Plant.
Paragraph 3.6.2 of this code establishes require-ments for the maximum reinforcement on groove welds. The standard acceptance criteria for the welds are also discussed in the "Connentary on Structural Welding Code" (AWS D1.2).
In the case of repair to' rupture restraints, which are non-standard structures, the design requirements of AWS D1.1 have been applied. Paragraph 1.1 of the " Commentary on Structural Welding Code" (AWS D1.2) statesi
"1.1 Application: The. Structural Welding Code, hereinafter referred to as the Code, provides welding requirements for the construction:of steel structures.
It is intended to be complementary with any' general code or specification for design and construction of steel structures.
This Code was specifically written for use in the construction of; buildings, bridges, or tubular structures, but its provisions are generally applicable to any steel structure.
When using the Code for other structures, owners, architects, and engineers should recognize that not all of its provisions may be applicable or suitable to their particular structure...."
PG&E believes that grinding the weld reinforcement back to the 1/8 inch required for standard structures would provide no benefit since the existence of the additional reinforcement is not detrimental to the structural integrity of the members.
In the case of weldments thicker than 1 inch PG&E has used the reinforcement requirement stated in ASME Section III, Part NB.
This code allows larger weld reinforcements for thicker welds.
The PG&E acceptance criteria discussed above appear acceptable because:
(1). The acceptance criteria meet the fabrication code for structures and vessels which are subject to more severe service than the rupture restaints.
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.(2). The rupture' restraint weldments are not subjectLto
._ fatigue or cyclic loading which causes.the stress intensi-
, 'fication effects of a stress-raiser to be of technical concern.
s (3). AWS DI.1;and DI.2 ~ allow the use of alternate acceptance criteria for non-standard structures such as the rupture restraints.
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d.
Findings
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The inspector examined Lin detail the eight weldments in the field and reviewed the Quality Control (QC) records for each.
of these welds. The welds, which join materials 1-1/2 inch-
-and 2-7/16 inch thick, are massive welds. The contact angles
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of the welds where stress raisers develop were examined and did not appear to be excessively abrupt. The QC' records demonstrated that all of the welds had been' examined by the NDE processes of magnetic particle testing and ultrasonic.
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testing' and were found acceptable.
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Conclusion
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Because:
1) exceptions to the' code are allowed for non-standard structures when" authorized by the owner, architect or engineer 2) the field examination of the welds and review of the records verified.the soundness of the welds; 3) the removal by grinding of excess reinforcement would not significantly affect stress. concentrations; and 4) the small contact angles -
of the eight welds it is' concluded that the variations allowed
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by the licensee in the subject weld reinforcements appear to be acceptable.
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4.
Modifications Resulting from the Verification Program-Unit I a.
Annulus Structural Steel Strengthening (50-275/82-35/01)
Initial modifications'to strengthen the structural steel in the annulus area of Unit 1 containaent were inspected.. The following completed modifications were inspected in the field,
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and the QC records were examined:
DCl-E-C-3114 Rev. 1 1)
Detail 4 at elevation 117', Columns 3, 4 and 6 2)
Detai1 7/8 at elevation 117', Columns 1, 2 and 4 3)
Detail 21 at elevation 106', Column 11 (stiffener plates only)
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Detail 30 at elevation 106', Column 12 These modifications appeared to comply with design detail requirements.
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b.
Piping Modifications The following modifications of the Component Cooling Water Piping to the reactor coolant pump upper bearing cooler were examined in the field, and the QC records were examined:
DC1-E-F-3232 Supply Piping, RCP-3 DC1-E-P-3233 Return Piping, RCP-2 DC1-E-P-3242 Return Piping, RCP-1 DC1-E-P-3246 Return Piping, RCP-4 DC1-E-P-3249 Return Piping, RCP-3 These modifications appeared to comply with design detail requirements.
c.
Electrical Raceway Modifications (50-275/82-35/02)
Miscellaneous modifcations to seven Electrical Raceway Supports performed under order DC1-EE-1301 and replacement of 3/4" conduit (K-3886) with 1" conduit performed under order DC1-EE-0695, Rev. 34, were inspected in the field. The QC record documentation for these modifications were also examined.
These modifications appear to comply with the design detail requirements.
d.
Pipe Support and Restraint Systems, Unit 1 Modifications to the following pipe supports located in the auxiliary building and containment were examined to determine by visual examination, whether the pipe supports met the requirements specified by the licensee's drawings, procedures, and installation specifications (ESD-223).
4-16SL 56S-118R 72-7R 92-108R 5-15R-57S-24V 72-11R 11-64SL 58S-IV 73-32V 13-20SL 58S-4V 85S-21V 13-35SL 58S-6V 85S-31V 55S-134R 66-14R 92-53R These modifications appear to comply with the design detail requirements.
No items of noncompliance or deviations were identifie <
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15.
- QC Surveillance of Onsit'e Contractors
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An 'examinati.on of Jhe licensee's heneral construction 'QC department's:
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. surveillanc'e' reports of the onsite contractors was initiated during this period.
Review of. surveillance reports for the electrical
. contractor (H. P. Foley;Co.),will be continued during a future inspection (50-275/82-39/01).
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Management Inter' view ~
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Meetings were held with the licensee representatives (identified-iii
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Paragraph 1) on' December 3 and 17,1982 to discuss the scope.and
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-findings of the inspections.
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