ML20209E052
| ML20209E052 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/05/1985 |
| From: | Bosnak R Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17083B484 | List:
|
| References | |
| FOIA-86-197 NUDOCS 8503140514 | |
| Download: ML20209E052 (5) | |
Text
a ur UNITED STATES
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8 NUCLEAR REGULATORY COMMISSION
,h WASHIP81T3N, D. C. 20555 i
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MAR 5 1965
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DOCKFT NO.: 50-323 HEMORANDUM FOR: Thomas M. Novak, Assistant Director for Licensing Division of Licensing FROM:
Robert J. Bosnak, Acting Assistant Director Components and Structures Engineering Division of Engineering
SUBJECT:
EVALUATION OF ALLEGATIONS ON DIABLO CANYON UNITS 1 AND 2 The flechanical Engineering Branch has evaluated the following assigned allegations, shown in the enclosure.
316 899 1092 These allegations are classified as D, per G. Knighton's memo of November 30, 1984...The enclosure also includes one unnumbered allegation, specific to Unit 2.
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Robect J. Bosnak, Acting Assistant Director Components and Structures Engineering Division of Engineering s
Enclosure:
As stated cc:
F. A erny, DE
- 7. Schierling, DL M. Ley, DL T. Sullivan, DE K. Manoly, RI CONTACT:
M. Hartzman, MEB:DE, x28445 C
h?To3/ Vocty[ff) h
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l ENCLOSURE Task:
Allegation or Concern No.
316 C
ATS No:
BN No:
Characterization:
A.Bechtel official approved the seismic review calculations en masse over several days without studying and properly reviewing the work.
Implied Significance to Plant Design, Construction, or Operation Possible design errors not discovered through independent checking and review may lead to overestimation of piping support load ca,rrying capacities.
Assessment of Safety Significance All computer based piping support designs and qualifications performed by PG&E site personnel were reevaluated by the San Francisco office. The concern of safety was addressed under the overall requirements of License Condition 2.C(11), Item 1.
Staff Position The resolution of this concern is addressed implicitly through the findings which are. fully described in SSER 25, Section 1.
This allegation is therefore considered resolved.
Action Required
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None g
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Task:
Allegation or Concern No. 899 ATS No:
BN No:
Characterization PG&E says they use more sophisticated techniques for more detailed analysis to show that pipe and supports are acceptable but the subsequent calculation which passed the support was less sophisticated.
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Implied Significance to Plant Design, Construction, or Operation Use of less sophisticated techniques may in some instances lead to overestimation of the load carrying capacities of piping supports.
Assessment of Safety Significance All computer based piping support designs and qualifications performed by PG&E site personnel were. reevaluated by the San Francisco office. The concern of safety was addressed under the overall requirements of. License Q.ondition 2.C(11), Item 1.
Staff Position The resolution of this issue is addressed implicitly through the findings which are fully described in SSER 25, Section 1.
This allegation is therefore considered resolved.
Action Required <k None.
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Task:
Allegation or Concern No.
1092 ATS No:
BN No:
Characterization Not all loads are considered in the calculation of small bore piping analysis (See SSER 26, Pg. E-5).
Implied Significance to Plant Design, Construction, or Operation Piping support load carrying capacity may be overestimated if not all relevant piping loads are considered in the support design and. qualification.
Assessment of Safety Significance All computer based support design and qualifications performed by PG&E site personnel were reevaluated by.the San Francisco office. The reevaluation was audited by an NRC-task group; the audit included checking if all relevant ~
loads had been included in the small bore support quhrification.
Staff Position The resolution of this concern is addressed implicitly through the findings which are fully described in SSER 25, Section 1.
This allegation is therefore considered resolved.
Action Required None.
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Task:
Allegation or Concern No.
ATS No:
BN No:
Characterization The procedure used by Bechtel, San Francisco for calculating shear stresses in welds is not conservative when compared to the procedure used by Bechtel, Gaithersburg(EPD).
For Diablo Canyon Unit 2 pipe support design Bechtel, EPD uses the procsdure-by Bechtel, SF.
Implied Significance to Plant Design, Construction, or Operation Weld load capacity may be overestimated because of incorrect specification of weld shear. areas.
Assessment of Safety Significance This concern was add'ressed by the staff during the audits in SF of selected pipe support qualification calculations.
In those cases where shear stress contribution appeared significant the staff requested further evaluation of weld stresses. All members were found to be acceptable per the applicable.
codes and project standards.
In addi$ ion, Bechtel EPD performed an evalua-tion of welds in a 5% sample of supports assigned to EPD by both procedures, which indicated that the majority of cases had an increase in weld stress of less than 5% and allowable stresses were not exceeded.
Staff Position
<g The methodology used by Bechtel for evaluation of weld stresses is acceptable and in accordance with current industrial practice. This allegation is therefore considered resolved.
Action Required
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None.
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