ML20063N855
| ML20063N855 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 09/20/1982 |
| From: | Root R WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Sternberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO1-82-0568, GO1-82-568, NUDOCS 8210070311 | |
| Download: ML20063N855 (3) | |
Text
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Docket nos. 50-460/513 i
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50.55(e) Report T-
~:0 Washington Public Power Supply System '.
P.O. Box 968 3000 George Washington Way Richland, Washington 99352 (509)3}2 5000 Docket Nos. 50-460 and 50-5,
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Septetber 20, 1982
/c G01-82-0568 Nuclear Regulatory Comm.ssion Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Attention:
Mr. D. M. Sternberg Chief, Reactor Construction Proj6 cts Branch No. 1
Subject:
PROJECTS 1 & 4 REPORTABLE CONDITION LUMPED MASS PIPE STRESS ANALYSIS LOADS
References:
1)
Telecon CR Edwards, Supply System to J. Ekhart, Region V Nuclear Regulatory Commission, dated January 14, 1982.
2)
Letter G01-82-0064, Supply System to NRC, dated 3/5/82, same subject.
Reference two (2) informed your office of a reportable deficiency under 10CFR50.55(e) concerning the use of lumped mass loads in the performance of pipe stress analysis.
Attachment "A" to this letter contains an updated description of the defi-ciency and the actions being taken by the Project to verify the safety signif-icance of the deficiency. Based on discovery of one case where ASME Code allowables were exceeded, we are submitting Attachment "A" as an interim report. At this time, it is not possible to provide a final completion date for the subject design analysis verifications. Therefore, the Supply System will continue to provide your office with interim status reports on a semi-annual basis.
If you hay questions or desire further information, please advise.
R. W. Root Acting Program Director, WNP-1/4 Attachment RWR:mb cc:
V. Stello, Director of Inspection, NRC A. Toth, NRC J.D. Batemen, UE&C 895 L.P. Laspa, Bechtel 861 V. Mani, UE&C 897 G. Valentenyi, UE&C, PA 08U6
[ 1-
! S210070311 820920 PDR ADOCK 05000460 i
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ATTACHMENT A WNP-1/4 DOCKET NOS. 50-460 AND 50-513 REPORTABLE CONDITION 10CFR50.55(e)
LUMPED MASS LOADING ON PIPING SYSTEM ANALYSIS BACKGROUND During a recent peer review conducted at the UE&C home office by th2 Supply System relative to the design of piping systems, it was determined that not all piping analyses had been performed in accordance with approved UE&C procedures.
In particular, it was determined that the use of lumped mass loads was not, in all cases, applied in accordance with the applicable procedure.
In one case, a lumped mass load was not applied at a change of direction in accordance with the applicable procedure which resulted in the ASME Code allowables being exceeded.
DESCRIPTION OF THE DEFICIENCY The currently aproved UE&C procedure for performing pipe stress analysis requires that between every two (2) supports and at a change of direction a lumped mass load is to be applied.
Contrary to the procedure requirement, not all pipe stress analyses were performed in this manner. UE&C Engineering has stated that for the case between two supports, the deviations were conscious decisions made by the Engineer, however, no record of the assumption or the rationale to support the decision has been documented.
The calculations in question had been checked and signed off by an independent second party.
Under the current checking system, there is no specific requirement for the checker to verify the details of the dynamic modeling of the lumped mass loads.
Verification of the model by the checker would have indicated whether or not lumped mass loads were accurately applied to the system.
SAFETY IMPLICATIONS The selected pipe stress analyses originally examined by the Supply System during the peer review and identified as not being consistent with the procedure have been reanalyzed by UE&C Engineering to include the lumped mass criteria.
It was confirmed that these as-designed systems were adequate, without any modification.
However, the reanalysis did confirm that piping stresses and support loads did increase in some of the reanalyzed systems, thus causing a degree of uncertainty as to whether design allowable limits will be maintained in all cases.
Stress margins exists for piping and pipe support designs.
The potential increases in niping stresses and pipe support loads were not expected to impact design adequacy.
However, as noted above, the case involving failure to place a lumped mass load at a change of direction, did result in piping stresses that exceeded the ASME Code allowables at one node. This case may be isolated, but a random sample investigation cannot conclusively eliminate the potential for an isolated case; therefore, corrective actions will be taken as described below.
CORRECTIVE ACTION The Supply System has identified the aforementioned discrepant conditions on Quality Finding Report (QFR) 99-1257 which was issued to UE&C on February 25, 1982. The recommended corrective action documented in the QFR assigned UE&C the task of reviewing all piping system analyses to identify which piping sys-tens deviate from the criteria for assignment of lumped masses.
Where dis-crepancies are noted, a reanalysis will be performed unless the mass changes are considered to be trivial. Resolution of trivial mass changes may be by
(
parametric studies if design margins are demonstrated to be adequate.
Further, the details of any parametric studies used as justification for reported analysis results must be made available to the Supply System for ev aluation.
The QFR also addresses the procedural inadequacy of the current " checking" program and requires upgrading of the procedure and further training of per-sonnel to attain compliance with ANSI N45.2.11.
STATUS The Supply System has reviewed UE&C's responses to the QFR but is unable to determine the extent of corrective actions necessary until additional design analysis data is gathered.
Due to the delay in WNP-1 construction and related manpower deficiencies the schedule for completion of the corrective actions cannot be provided. Therefore we will continue to provide interim status reports on a semiannual basis.
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