ML20211B819
| ML20211B819 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Diablo Canyon |
| Issue date: | 03/05/1982 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20209B155 | List:
|
| References | |
| FOIA-86-151 NUDOCS 8610210158 | |
| Download: ML20211B819 (1) | |
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UNITED STATES
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f Docket No.: 50-275 MEMORANDUM FOR: Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation FROM:
Robert L. Tedesco, Assistant Director for I.icensing Division of Licensing
SUBJECT:
PROPOSED BOARD NOTIFICATION - TRIP REPORT (2/22-26/82)
REGARDING SEISMIC DESIGN VERIFICATION PROGRAM I recomend that the enclosed Board Notification be transmitted to the Comission.
O'-W Robert L. Tedesco, Assistant Director for Licensing Division of Licensing 8610210158 860930 j
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l Docket No.: 50275 HEMORANDUM FOR: Chaiman Palladino Comissioner Gilinsky Comissioner Bradford Comissioner Aheame Comissioner Roberts FROM:
Darrell G. Eisenhut, Director Division of Licensing Office of Nu, clear Reactor Regulation
SUBJECT:
INFORMATION' ITEM - TRIP REPORT (2/22-26/82) REGARDING SEISMIC DESI,GN VERIFICATION (B0ARD NOTIFICATION 82-23)
In~accordance with present NRC procedures regarding Board Notifications, the enclosed trip report (2/22-26/82) by K. Herring and J. Fair regarding the Diablo Canyon Seismic Design Verification Program is provided to the Comission for infonnation. This material is relevant to the safety issue on seismic design adequacy of the Diablo Canyon Unit 1, which is currently before the Comission for consideration.
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Darrell'arrG. Eisenhut, Director e
Division of Licensing Office of Nuclear Reactor Regulation
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MAR 3 1982 MEMORANDUM FOR: Frank Miraglia, Chief Licensing Branch No. 3 Division of Licensing, NRR f
FROM:
Kenneth S. Herring Systematic Evaluation Program Branch Divison of Licensing, NRR John R. Fair Engineering & Technical Support Branch Divison of Engineering and Quality Assurance, NRR
SUBJECT:
DIABLO CANYON SEISMIC VERIFICATION PROGRAM INSPECTIONS - FEBRUARY 22 - 26, 1982 As a part of Region V's ongoing acti.vities to keep abreast of the current Diablo Canyon seismic verification program, we conducted unannounced inspections at the R. L. Cloud offices on February 22 and 23,1982, and at the PG&E, offices on February 24, 1982.
In addition, a walk-down of cer-tain aspects of the Diablo Canyon design was conducted at the plant on February 25 and 26,1982, to gain a better understanding of issues identi-fied during the meetings at the R. L. Cloud and PG&E offices. Our observa-tions and reconinendations are discussed below.
R. L. Cloud Inspection
- 1) Piping and Supports The piping analysis procedures, signed on 2/22/82, were reviewed.
The procedures were based on criteria presented in Section 8.2 of the Hosgri Report with additional criteria for overlap (NUREG/CR-1980),
decoupling (piping diameter ratio >4) and small diameter piping con-nected to large pipe (either (1) large pipe response in the span where the attachment point is located is greater than 20Hz or (2) the large line displacement (1/16 inch). The procedures did not include the load combination or stress allowable criteria.
Two of the R. L. Cloud employees performing piping analyses were inter-viewed. These employees were familiar with the piping analysis proced-ures and criteria.
Approved support evaluation procedures were not available at the time of the inspection. The support friequency calculations were available but they had not been approved at the time of the inspection. The re-sults of these calculations showed 19 of the 20 supports met the PG&E criteria for frequency as reported in the R. L. Cloud progress report dated January 9,1982. Review of the calculations showed that snubber 4
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' flexibilities had not been included in the computations. Cloud employees stated that these calculations had not been approved and the snubber flexibilities wo01d be included in the final calcula-tions.
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- 2) Equipment Calculation Review' J
The only completed, checked and approved calculation packages in any area were those for the Main Annunciator Cabinet located in the Cable Spreading Room and the Diesel Generator Fuel Oil Priming Tank. Review of these calculations indicated the following.
i a) Main Annunciator Cabinet - In the calculation of the cabinet response,1) 12 ga. sheet metal side panels ( 25" x 85") were i
treated as simple beans without verification of the appropriate-ness of this assumption, 2) angle structural members were treated as simple beams without appropriate consideration..of torsion, and
- 3) the locations of the centroids of the angles IWre computed er-roneously. The last error was found to be due to an error in the handbook used for calculations, however, it appeared that insuf-ficient consideration was given to the applicability of handbook formulas and the basic assumptions ingrained in handbook and simple beam formula formulations. Dr. Cloud agreed that the calcuation I
should be redone. He further indicated that this calculation, in addition to 3 others, had been performed by EDAC under a previous, since cancelled, subcontract. These other calculations were found to be inappropriate by Cloud personnel and were being redone. The cabinet calculation was not checked in as much detail as the other 3 since it indicated that an.E01 was to be generated. Therefore, he felt that this was an isolated occurance of an approval of an erroneous calculation.
b) Diesel Fuel Oil Priming Tank - No oby'ous errors were detected in the review of this calculation. However, insufficient attention was given in the evaluation of the concrete anchor bolts used for the supports. This appeared to be due to the low magnitude of the calculated seismic responses, however, we indicated to Cloud that these should be appropriately evaluated in all future calculations.
Given that an error was found in 1 of the 2 completed equipment calcula-tions reviewed, it is reconnended that the NRC staff review additional com-pleted equipment calculationt to determine whether or not this is an t
isolated case.
In addition, it was observed that procedures for perform-ing the analyses of all items in the Cloud verification effort have not yet been finalized by Cloud.
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PG&E Inspection
- 1) PG8E and Blume Civil Engine'ering Related Calculations Several topics related to the calculations performed by the PG&E and Blume Civil Engineering personnel were discussed. These discussions are described
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a) Containment Polar Crane - Discussions similar to those which took place on January 29, 1982, between Mr. Herring and PG8E and Blume personnel were reported.
Since that first discussion, PG&E had no new information relative to this issue and indicated that they intended to pursue it fu rther.
(See Trip Report K. Herring to F. Miraglia, February 3,1982.)~
b) Containment Internal Structure Response Above Elevation 140' - The steam generator and pressurizer enclosures which extend about 40 feet above the operating deck (el.140') were not modeled in the containment -
structural model. Therefore, floor spectra at eil.140' were used for the design of piping and equipment attached above el.140' and coupled to these enclosures. The effects of the enclosure flexibility are be-ing evaluated. They indicated that affected items include Main Steam and Containment Spray piping, and the safety and power operated relief valves. The analysis of the Containment Polar Crane in the parked and locked position (at the tops of the steam generator enclosures) is also affected since the flexibility of these enclosures was not considered in Blume's analyses of this crane.
c) Containment Pipeway This steel frame structure, attached to the containment shell exterior, was initially assumed rigid.
It appears that this assumption is not valid and the effects of its flexibility are being investigated. PG&E indicated that items affected include the Main Steam, Main Feedwater and Auxiliary Feedwater piping, and the Main Steam Isolation Valves.
d) Main Annunciator Cabinet - PG&E is analyzing the cabinet flexibility l
in light of Cloud's finding that it was not rigid as assumed initially.
They indicated that their prelimiary calculations were demonstrating that the cabinet was rigid. However, the PG&E personnel performing the anal-yses were not aware of the connection details for the doors, internal member and cabinet supports to substantiate the validity of the assump-tions made in their analyses.
e) Containment Exhaust Vent Structure Flexibility - Blume initially deter-mined (November,1970) that the exhaust vent had a natural frequency of 50 Hz and notified PG&E of this fact.
In December,1970, Blume determined that the 50 Hz was in error and that the frequency was 2 Hz.
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4-However, they never notified PG&E of this change. Hosgri evaluations done by PG8E relied upon the 50 Hz frequency and determined that the vent would remain elastic. ~PG&E' stated that with a 2,Hz natural fre-quency, recent evaluations indicate that modifications are required for the vent to remain elastic under the Hosgri criteria and they are evaluating the feasibility of a non-linear analysis to demonstrate
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acceptability without modification.
l f) Annulus Spectra Revisions - Three revisions to the containment annulus spectra have occurred since the initial discovery of the I
annulus problem. The first accounted for appropriate orientation, and the second acccunted for appropriate mass and stiffness distri-butions. PG8E indicated that the latest revision has been necessitiated by biume discovering (in a recent internal Blume de-
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sign audit) that the upper vertical massess of the internal struc-ture in'the initial Hosgri analyses inappropriately included such items as the Steam Generator, Reactor end Reactor Coolant Pumps.
i In addition, the two masses of the internal structure were trans-posed in the recent evaluations.
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Given these and previously identified problems relating to the analyses performed by Blume, PG&E stated that they were currently formulating a program to, be instituted by Blume to check the adequacy of Blume's past analyses and to identify appropriate final analyses results. We indicated that we concurred with the need for such a program.
- 2) PG8E Piping Design and Construction Recent R. L. Cloud progress ~ reports have identified several as-built descrepancies during piping walk-downs. One issue identified was valve operator orientation. Correct measurements of valve operator orien-tations apparently were not made during the IE Bulletin 79-14 walk-downs.
PG&E currently plans to walk-down all piping to record correct valve orientations.
According to PG8E the majority of the as-built dimensional descrepancies identified by Cloud were errors in drafting and not in the analyses.
PG&E stated that the original piping drawings that were marked-up during the field as-built walk-downs were used by the piping analysts. These drawings were then sent to the drafting department to develop the final i sometrics. These drawings were not treated as record drawings and therefore, were not subject to stringent quality control procedures.
PG&E currently plans to upgrade the drawing controls on the piping iso,
metric drawings and they also plan to perform a sample of 17 walk-downs to the IEB 79-14 criteria. This effort will require further NRC review when PG8E conpletes the current evaluations on all open items.
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- 3) Ongoing PG8E Investigations In addition to the work described above, PG&E is in the process of instituting strong project management control of the in-house seismic reverification effort. Since PGAE has initiated and is initiating
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several additicaal internal programs to address the concerns identified by Cloud and themselves, it is recomended that the NRC staff meet with t
PG8E to discuss the adequacy of these programs and to address the open items identified to date. Special attention should be given to assuring that the resolution of problems is approached in an orderly fashion.
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Site Visit Observations On our site visit, we' inspected the containment exhaust vent, the steam gen-
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erator and pressurizer enclosures, and the Main Annunciator Ca' binet. Our observations are presented below.
1)- Containment Exhaust Vent From a visual inspection of this structure, it appeared obvious that the natural frequencies were substantially lower than the 50 Hz calculated initially by.Blume, and used by PG8E in its Hosgri evaluation of this structure.
- 2) Steam Generator and Pressurizer Enclosures From a visual inspection of these structures, the potential for further amplification of motion dove el.140' appeared obvious, especially con-sidering the connection of the Polar Crane to the steam generator enclo-u res.
- 3) Main Annunciator Panel From a visual inspection of this panel, it was observed that:
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a) The conception of this cabinet ingrained in the Cloud analyses was more representative of the physical configuration than that i
ingrained in recent PG&E evaluations.
b) The analysis performed recently by PG8E contained several as-j sumptions which were not representative of the physical situation.
l c) Several loose and missing bolts were obvious.
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4 Based upon the above cbservat19ns.and the previous discussions of the problems in these areas, it appears that many of these problems could,
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i have been avoided if analysts had been required to walkdown these structures.
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y Summary of Status of Design Verification on Diablo Canyon, Unit 1 1.
Sumary of Initial Review with Applicant A low power 1.icense was issued by NRC for low power operation on September 22, 1981. On October 9,1981 a meeting was held with the Pacific Gas & Electric Company (PG&E) and its consultants Drs. Blume and Dr. Cloud to discuss the discovery of an error in the seismic analysis of the piping systems within the annulus area of Unit 1 containment. PG&E stated at this meeting that it was their view that this error would affect only a limited area of the plant. PG&E stated that they were reviewing all affected piping systems within the containment annulus and have identified where certain piping support modifications are requied. Moreover, PG&E has hired a consultant, R. L. Cloud Associates, Inc., to perform an independent audit review of all safety related systems to determine whether the error is limited to a small area of the plant or whether the error is indicative of larger problems.
Foliowup meetings on this matter were held with the Pacific Gas
& Electric Company on October 9. October 14, November 3,1981 and on February 13, 1982.
2.
Low Power License Design Verification Prerequisites By Comission Order (CLI 81-30) dated November 19,1981 PG&E's low power license, issued September 22, 1981, was suspended and the applicant was requested to provide the following information in order to make a finding on the lifting of the suspension:
,(a ) An evaluation of all seismic service-related contracts prior to June 1978; (b)
Infomation and results of an independent design verification program; (c) A technical report that fully assesses the basic cause and significance of all design errors; (d) PG&E's conclusions on the effectiveness of the design verification program; and (e) A schedule for completion of any modifications to Diablo Canyon, Unit 1.
PG&E submitted its proposed reverification program in response to the Comission Order on December 4,1981. A meeting was held on February 17, 1982 with representatives of Governor Brown and Joint Intervenors to solicit their coments on the above cited PG&E submittal. The staff issued its evaluation, dated March 1,1982, of PG&E December 4,1981 submittal.
Furthemore, the staff briefed the Comission on March 4,1982 of its findings.
In sumary, the staff found PG&E program, with staff recomended modifications, satisfied the requirements of the Comission Order.
The Comissioners accepted the staff's findings and directed all parties to submit, within one week, a list of proposed independent auditors.
3.
Full Power License Design Verification Prerequisites By NRC letter dated November 19, 1981 we requested that PG&E provide the following information prior to proceeding beyond 5% of rated power. This information would be used in developing the full power requirements. -
3.1 For All Non-Seismic Service - Related Contracts Prior to June'1978 (a) The results of an independent design verification program of all safety-related activities perfonned prior to June 1,1978 under all non-seismic service contracts utilized in the design process for safety-related structures, systems and components.
(b) A technical report.that fully assesses the basic cause of all design errors identified by this program, the significance of design errors found, their impact on facility design.
(c) PG&E's conclusions on the effectiveness of this design verification program in assuring the adequacy of facility design.
(d) A schedule for completing any modifications to the facility that are required as a result of this program. For modifications that PG&E proposes not completing prior to operations above 5% power, the bases for proceeding should be provided.
3.2 For PG&E Internal Design Activities (a) The results of an independnet design verification program of PGLE internal design activities performed on Diablo Canyon Unit I related to the development of the design of a suitable sample of safety-related structures, systems or components.
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(b) A technical report that fully assesses the basic cause of all design errors identified by this program, the significance of design errors found, and their impact of facility design.
(c) PG&E's conclusions on the effectiveness of this design verification program in assuring the adequacy of facility l
design.
(d) A schedule for completing any modifications to the facility that are required as a result of this program.
For modifications that PG&E proposes not completing prior to operations above 5% power, the bases for proceeding should be provided.
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3-I 3.3 For All Service-Related Contracts Post-January 1,1978 (a) The results of an independent design verification program of a suitable sample of the activities performed on Diablo Canyon Unit 1 by each service-related contractor that were completed subsequent to January 1, 1978 related to the development of the design of safety-related structures, systems and components.
(b) A technical report that fully assesses the basic cause of all design errors identified by this program, the significance of design errors found, and their impact on facility design.
(c) PG&E's conclusions on the effectiveness of this design verification program in assuring the adequayc of facility design.
(d) A schedule for completing any modifications to the facility that are required as a result of this program.
For modifications that PG&E proposes not completing prior to operations above 5% power, the bases for proceeding should be provided.
3.4* Qualifications of Companies proposed to Conduct Independent Reviews A description and discussion of the corporate qualifications of the company or companies that PG&E would propose to carry out the various independent design verification programs discussed in 1 through 3 above, including information that demonstrates the independence of these companies.
4.
Certification of Conformance to Application Regarding Design and Construction.
None.
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