ML20209C293
| ML20209C293 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/21/1983 |
| From: | Knight J Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16340C148 | List:
|
| References | |
| FOIA-86-151 NUDOCS 8307250669 | |
| Download: ML20209C293 (121) | |
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JUL 11 MEMORANDUM FOR:
Assistant Director Division of Lir sing I
FROM:
James P. Knight, Assistant Director for Components ar.d Str9ctons Engineering Division of Engineering
SUBJECT:
CSE INPUT FOR SUPPLEMENT TO SAFETY EVALUATION REFORT ON DESIGN VERIFICMION PROGPM - DIABLO CANYON N!JCLEAP.
POWER PLANT, UNIT 1 Plant Name: Diablo Canyon Nuclear Pcwcr Plant, Unit 1 Applicant: Pacific Gas & Electric Licensing Stage: License Suspended and Currently under Review Docket Number: 50-275 Responsible Branch:
LB-3, H. Schierl'in'g, LPM Status: Review Continuing t
Enclosed is the draft CSE incut to the subject SSER, S9ction 4.0, Seismic Design Verification. The review was perfor:r.ed by the CSE stcff and its consultant, Brookhaven National Laboratory, based on the Phase I Final Reports submitted by the Otablo Canyon Project (DCP) and by Teledyne Engineering Services (TES), the Program Manager of Independent Desiga Verification Program (IDVP), and attendance of the many technical interchange meetings held by the DCP and the IDVP.
The enclosure includes inputs from the Structura; ard Geotechnical Engineering Branch (SGEB), the Mechanical Engineering Branch (MEB), cnd the Equipment QualificationBranch(EQB). Section 4.5.1 was prepare;I by Baned Jagannath of the SGEB, Sections 4.3, 4.4 and 5,3 were prepared by Mark Martzman of the MEB, Sections 4.5.2 and 4.5.3 ucre prepared by Arnold Lee of the EQB, ar.d the remaining sections were prepared by ilarold Dolk of the SGES.
W4 If James P. Kn at[ Assistant e: tor for Com patints & Structyres Engineering Division of Engineering
Enclosure:
As stated cc: See page 2 q.vnw%&
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e SUFFLEMENT TO SAFETY EVALUATION REPORT l
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'QESIGN VERIFICATION PROGRAM i
DIABLO CANY'ON UNIT 1 4. 'O Seismic Design verif-ication i
i 4.1 Introduction 4
Following the diagram error reported by PG8E on September 28, 1981 as
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previcusly discussed in Sections 1.0 and 2.0 of this SSER, a reverification prograr. for the design adequacy of structures, systems
.and components was initiated by the Diablo Canyon-project (DCP). The licensee engaged URS/ John A. Blume & Associates, Engineers, the original seismic design service contractor, to conduct an independent internal review of its liosgri-related civil-structural analysis and design work.
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In the meantime, the Independent Design Verification Program (IDVP) was established in response to the Consission Order (CL1-81-30) which l
required performance "of an independent design verification of all safety-related activities perfonned prior to June 1,1978 under all i
seismic-related service contracts utilized in the design process for safety-related structures, systems, and components." Furthermore, the a
L staff engaged Brookhaven National Laboratory (BNL) as,its own consultant to independently assess in detail the design adequacy of selected structures and piping systems and to provide an independent assessment j.
of the' efforts undertaken by the DCP and the IDVP.
BNL personnel.
participated in most of the technical meetings and assisted the staff in i
reviewing the Phase I Final Report submitted by the DCP and the Interim Technical Reports (ITRs) and the Phase I Final Report issued by the IDVP. This section provides a summary description of the scope,
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criteria, and methodology involved in each of these efforts.
4.1.1 PG8E Irdeoendent Internal Review PG4E's independent internal review project connonly referred to as the l
Blume Internal Review (BIR) was conducted by URS/ John A. Blume &
Associate, Engineers (URS/Blume). The scope of the BIR project included only structures or structural components of the Diablo Canyon Nuclear Power Plant (DC.VP) that were analyzed and/or designed by URS/Blume.
l The effect of possible response spectrum variations on equipment and j
piping analyses was not within the scope of this work.
The original objectives of the BIR project were to establish either that the work done met the revised seismic criteria based on the postulated Hosgri fault effects or that, with the application of appropriate judgments that were censonant with good engineering practice, the results of the work could be reconciled with the revised criteria and with as-built structures and structural components. However, when Bechtel Power Corporation was engaged to assume responsibility of Project Ccmplation Manager for the DCNPP, the emphasis of the BIR Proje~t ws.; shifted frem identifying and evaluating discrepancies to c
primarily identifying discrepancies and identifying areas where the review was to be completed by the DCP Internal Technical Program (ITP).
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4 The basic review was ccnducted by URS/Blume personnel who are experienced in seismic analysis but who had littia or oc involvement in the analysis ~or design of the specific structure or structural components reviewed.
Evaluation of reviewer corsnents and resolution of the concerns implied by them was performed by URS/Blume personnel who were familiar with the analyses and structures. When some implicai; ion of uncertainty in the seisnic capacity of a structure or structural component was found, it was identified, described in detaib and b cught to the attention of Pacific Gas and Electric Company (PG8E), along with an evaluation of its impact, and recommended ccrrective actions.
The results of this review was published in a report entitled "Blume Internal Review (BIR):
Independent Internal Review of TNi Work Doie By URS/Blume Engineers en the Diablo Canyon Nuclear Power Flant", dated September, 1982. A total of 150 review coments were made. The.
majority of them was categorized as QA comments involving classification and augmentation of calculation files, or verification of computer programs.
In terms of impact on DCNPP seismic performance, 108 items were determined to have none or insignificant ' impact while the impact of the remaining items were lef t to be detemined by the ITP and the IOVF.
4.1.2 Independent Design Verification Program (IDVP)
The IDVP managed by Teledyne Engineering Services (TES) was divided into two phases. Whereas the Phase I program censidered the response of safety-related structures, systems and components to the postulated I
I Hosgri 7.5M earthquake and evaluated the msults relative to the licensing criteria applicaole to that event, the Phase II prcgram considered non-Hosgri seismic conditions with associated loadings and other aspects of safety systems and. analyses relative to the criteria of the license application. Sections 4.2 through 4.7 will address only the seismic-related activittes performed under Phase I and II programs.
As stated in previous sections, the objsctive of the IDVP was to conduct an independent and in-depth review of all safety-related activities performed prior to June 1,1978 by P2&E and its : seismic service-related contractors. On a statistical sampling basis, the review would determine the adequacy of the DCNPP seismic design for all safety-related structures, systems, and components or identify errors which led to inaccurate results or violations of desigt criteria.
Ic general, the IDVP cffort involved in the following tasks.
1.
Establish an initial sample of. original work subject to verification.
2.
Establish the organizations participating in the original work (DesignChain).
3.
Perform a QA audit nd review of the applicable organizations.
't 4.
Perform a preliminary evaluation of the initial sample.
C.
Feoort ihitial concerns resulting from steps 3 and 4 abose.
G.
Ferfor-n additional varificttion to resolve the specific initial concerns with.mspect to criteria of the License Application and report the resolution.
7.
8ased o'n steps 1-6, iderttify any additiora1 samples which cust be considerett and additional verification requireo for evaluattor, of any Generic :oncerns.
6.
For the subjects identified in step 7, repeat step: 4 7.
9.
Identify all aspcets which require DCr efforts, iceluding
' ccrre::ti te at: tion, and refer then to t:1e CCP.
- 10. Verify the CC? corrective action taken in direct response to the IDVP.
Task 7 has lost much of its significance tnring the course of this program sin e the CCP initiated the ITP which provided a mechanf sm for evaluation of i;he majority cf tha generic concerns.nd essentially climinated tue need for additional sGapling.
The a:ceptance criteria used in the IDVP review were tncss appfoved in the FSAR and its a'ncr.dments. The seismiO irputs consisting of ground cesign respa.1se spectra and corr:!sponding acceleration time histories ostulated 7.5M Hosgri earthqucke (Hosgri), Double developed for the p(DDE), and Des 1gn EE.rthquake (DE) were used in the Design Eartnquake 13'lP evaluation. The bases for the HOSG*AI, DDE, ar.d DE.were previcusly approved t,y the \\SLB and ASLAB and were therefore excluded from the IDVP review.
In perforriing tne IDVP, the methodology and acceptance criteria used in th! evaluation were given in Section 5.4 of Apperidix 0 to the IDVP i
report entitled "Diablo tanyon Nuclear Power Plant - Unit 1, Phase 1 Pr'agram Management Plan" submittej by 725, dated March 29, 1982.
l As of Jer.e,1983, a tatal of 321 Errors ar,1 Open Itiam Reports (EDI) ar.d 49 Interim Techr.ical Reports (ITR' were issued. Among the 321 EDIs, 250 were resolved ar.d Progr3r.Resciution Reports were filed. These E01s dho ITR$ wil) be ioentified and addraued in the evaluation of individual bt.11dirgs, systems ard ccmpcnents given in tht following sections.
4.1.3 Jndeoendent "tuoi_es Perfomed by Brookhaver. National Laboratory _
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At the staff':s request, BNL initis11] undertook the task to perform vertical seitmic analis1: for the Unit I containment annulus structure and te nr.alyze two pi' ping syt,tems with PG8r. designation numbers AA-26 I
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and 6-11 located in the contair. ment anr.ulus area of the DCNPP. The objectives of this effort were tc evaluate the adequacy of the original n
PGSE structural and piping model and the computational techniques j
employed. Several discrepancies in the areas cf mass calculations, nedel assusiptions, ur.d response spectrum smoothing techniques were found. The results were published in NUREG/CR-2834 entitled "Ir. dependent Seismic Evaluation of the Diablo Canyon Unit 1 Containment AnmJlus Structure and Selected Piping Systems", dated August,1982.
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As it became apparent frei the results of this study that serious i
discrepancias existed in the PG&E analysis. BNL was requested to expand I
its study to include the following additional independent analyses es described in SECY-82-414.
1.
Independent horizontal seismic analysis for the annulus structure, l
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Seismic and :, tress analysis of one buried diesel oil tank, and
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Ind; pendent analyses for two additional piping problems
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(une of Westinghouse scope a.1d one cf FG8E scope).
f Thate areas were chosen to provide the ste.ff with confinnetory information in areas that either were not included in the DCP corrective i
action program at the time or to complete the previous BNL analyses efforts.
The results of the horizontel analysi'; of the containment ennulus j
structure were presented in a public meeting or. February 15, 1933 and i
submitted to the staff in a letter from Dr. M. Reich of BNL dated May 17, 1983.
It was concluded from thirstudy that the flexibility and the i
torsienal respcnse of the annulus structure were important to the j
response calculations but were ignored in the original FGSE's analysis.
i The results of the burited diesel oil tank study were presented in two pablic meetings on June 17 and.lulv 6, 1983 ard were re @ rted to the staff in a letter frosi Dr. M. Reicli of BNL dated July 18, 1993.
It was found that the original PG6E's model used by Harding ard Lawson l
Associates (HLA) to perform the analysis for tha buried tanks was
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incdequate.
It led to substantially reductions in results.
I Tne analyses for ths two additional piping problems went limited to the computhtien cf natural frequencies and mode shapes. There were generally good 6greement betNeen the values ootained from the BNL analyscs arid these from the origiral ?G6E analyses. The results of this study waro reportsd to the. staff in letter from Dr. M. Reicn of 8NL j
dated April 11, 1983.
j Details of each of tnese analyses will be further discussed in Section 4.6.
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'O 5-4.1,4 The DCP Internal Technical Program The DCP cn its own initiative engaged in a corrective action effort referred to as Interna'l Technical Program'(ITP). The primary objectives of the ITP as stated by the DCP were to (1) provide an additional design review effort to assure the overall adequacy of the analyses and design of the plant; (2) develop data and information in support of the IDVP; (3) respond to IDVP open items and findings; and (4) implement design modifications or other corrective actions arising from the IDVP and the ITP. The secpe of the ITP was expanded from an initial sampling approach to a comprehensive design review of the plants safety-related structures, systems, and components. Except otherwise noted and justified tha criteria and the dynamic analysis procedures and methods utilized by the ITP were taken fran the FSAR nnd its amendments and were described in SER Section 3.7 and Supplements 7 and 3 to the SER. To date, modifications have taken place in the ccntainment annulus structure, fuel handling building, intake structures and in some other areas. The modifications will be further addressed in the evaluation of individual buildings, systems, and components given in the following secticns.
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4.2.1 Containment Annulus Structure 4.2.1.1 Introduction The annulus structure is a Design Class I Structure located within the containment between the crane and the containment shell.
It is attached directly to the crane wall which provides lateral support and the containment floor, but is not connected to other parts of the containment. The annulus is a welded and bolted structural steel frame extending from elevation 91 feet (top of, base slab) to 140 feet.
Radial and tangential beams of the annulus structure support piping, equipment, and walkways. The three lowest floor levels (elevations 101 feet, 106 feet, and 117 feet) are structural steel, while the floor at elevation 140 feet is a composite concrete and steel deck with a nonmoment-resistir.g connection to the top of the crane wall.
Some of the beam-to-column connections at the lower elevations are moment resisting.
Radial beam to crane wall connections are bolted.
The primary sources of the data used by the staff in its evaluation are listed below.
1.
The IDVP Diaolo Canyon Nuclear Power Plant - Unit 1 Final Report.
2.
The Pacific Gas and Electric Company Phase I Final Report Design Verification Program.
3.
Technical interchange meetings between the IDVP and PG&E as documented in the staff trip reports.
4.
Brookhaven National Laboratory independent evaluations as doucmented in the NUREG/CR-2834 report as well as related letter reports.
4.2.1.2 PG&E Previous Seismic Analysis Originally, PG&E utilized a five-frame dynamic model for the vertical an'alysis of the annulus.
The 18 radial frames of the structure were condensed into 07/14/83 1
DIABLO CANYON SER 4.2.1
I i
e-9 5 frames which represented the area halfway between each of the 5 fan coolers located on the concrete floor at elevation 140 feet. The tangential beams between the 18 individual frames were not represented in the' dynamic model.
The crane wall was modeled as a rigid member so the five frames were essentially independent and uncoupled.
After the " diagram error" was uncovered, the five-frame model analysis was revised. The revised PG&E model, also referred to as the 1981/1982 URS/8lume model, included corrected mass data, increased' nodes ontheradialeiements,andmorerealisticrepresentationsofthestructural connections.
4.2.1.3 Brookhaven Analysis The NRC engaged the services of Brookhaven National Laboratories (BNL) to perform an independent seismic analysis of the annulus structure. The BNL vertical seismic analysis utilized a three-dimensional model and time-history dynamic analysis techniques.
The model included most of the structural steel members, therefore, many local modes of vibration were computed.
The tangen-tial beams were found to respond to the earthquake excitation and affected the floor response spectra.
NRC (Denton) letter to TES (Cooper) of July 1, 1982 requested TES to review the validity of the enclosed BNL report and the specific concerns raised therein part of the Phase I verification effort.
BNL also performed a three-dimensional time-history analysis for horizontal excitation. The crane wall, which is more flexible in the horizontal direc-i tion, was included in this model.
The results of this analysis were presented to the IDVP at a meeting on February 15, 1963 and documented in a letter from l
l Dr. M. Reich of BNL to the staff dated May 17, 1983. This analysis showed that i
the flexibility of the annulus steel is important for the horizontal response.
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The spectral acceleration at the crane wall was much lower than those on the steel portion of the annulus.
The study also showed that input in one direc-l tion produced a significant response in the other direction.
This response is produced by the torsion in the annulus steel frame.
As a result the Project l
initiated a frequency study of the annulus for horizontal response and deter-mined that modifications were required.
These modifications were necessary l
to stiffen the structure.so that the floor response spectra would be nearer to the floor response spectra used for piping and equipment qualification.
07/14/83 2
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4.2.1.4 IDVP Review The IDVP performed a field walkdown inspection of the annulus structure to verify the as-built condition. kheIDVPreviewedthe 1981/1982 URS/Blume five-frame model, also known as the PG&E analysis and the BNL three-dimensional model used to analyze vertical excitation.
The review of the PG&E model resulted in two areas of concern.
1.
The frame consolidation meth'od used to obtain the equivalent radial beam flexural rigidity properties.
2.
The PG&E model does not consider the possible effects of the tangential beam flexibility on local response spectra.
The IDVP concluded that:
1.
The frame consolidation does not adequately represent the structure at elevations 101 and 106 feet.
2.
The IDVP studies' included simple one and two degrees-of-freedom lumped mass models which confirmed that the tangential beam flexibility is an important factnr in the response spectra generation.
The IDVP have not completed their verification efforts. The results and conclusion will be reported in ITR 50 which was scheduled for a draft release i
i on November 5, 1982.
This document has not been submitted to the staff.
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The following conclus. ions were presented in the IOVP final report, l
1.
There are no significant differences in the computed masses and member j
joints between the 1981/1982 URS/Blume analyses and BNL (Model B) analysis.
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The joint characteristics in the Blume analysis realistically represent the as-built configuration.
07/14/83 3
DIA8LO CANYON SER 4.2.1
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The spectra seccthing technique applied by PG&E is consistent with th'e DCNPP Ifeensing criteria.
1 Three EDIs were issued specifically against the annulus structure (3006, 3007, and 3008).
These E0Is were combined with E0I 1014 which was defined to track verification of DCP corrective actio on the containment structure A
including the annulus.
4.2.1.5 Verification of DCP Corrective Actions The DCP has implemented an extensive corrective action program and the annulus structure has been reanalyzed to account for the concerns raised in EDIs 3006 and 3007. The OCP-conducted its evaluation of the criteria implementation and qualification analyses through the' Internal Technical Program.(ITP).
The DCP reviewed the as-built drawings to ensure accuracy of input to the analyses t
and made modifications as necessary, as stated in the PG&E Phase I Final i
Report.
The DCP methodology included all essential. steps of the qualification process.
The OCP supplied a calculation index which documented the qualification anal-yses and computer files of record and served as the basis for selection of the IOVP sample of OCP qualification analyses.
The IOVP design review included assessments of the completeness, applicability, and consistency of the DCP review and reanalysis methodology.
The DCP sample files chosen for review were:
1.
Vertical seismic analysis of radial frame #6.
2.
Vertical seismic analysis of radial frame #14.
3.
Horizontal frequency analysis of elevation 101 feet.
4.
Horizontal frequency analysis of elevation 117 feet.
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01ABLO CANYON SER 4.2.1
I The IDVP plans to sample additional files relative to member evaluation when such files are,available.
No E01s have been issued for the annulus with regard to the DCP Corrective Action Program.
The IDVP verification program is not yet complete.
Pending completion of ongoing efforts, the IDVP considers the following aspects of the DCP work to be unresolved issues:
1.
Whether the horizontal floor response spectra developed for the annulus properly reflects the dynamic charac'teristics of the interior structure.
2.
Whether the physical modifications in progress to stiffen the annulus for horizontal excitation will ensure compliance with the proposed criterion that the minimum frequency be 20 Hz.
The IDVP intends to formulate a final conclusion as to the qualification of the annulus structure and its conformance to licensing criteria when all analyses have been evaluated by the IDVP.
This evaluation and conclusions will be reported in ITR 51.
- 4. 2.1,6 DCP Work 4.2.1.6.1 Seismic Model The seismic analysis,and design of the containment and internals were reviewed to assure that the models used previously in the Hosgri, DE, and DDE analyses represent the as-built conditions.
Based on this review, new model properties for the annulus structure were developed and this structure was reanalyzed. As a result of this reanalysis, new response spectra for the annulus structure were developed.
The vertical responses for the Hosgri event was determined by a time-history, modal superposition analysis of lumpad-mass models of individual radial frames with single-degree-of-freedom oscillators to model the response of tangential 07/14/83 5
DIABLO CANYON SER 4.2.1 e
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Coupled models incorporating both the concrete internal structure and the steel annulus structure were used. Masses for the internal concrete are lumped at elevations 140 and 114 ft.
The crane wall serves as a common support for the individual frames, each frame carrying its proportion of the load of a' fan ~ cooler at elevation 140 ft and of various pipes at lower J
levels.
The vertical response for DE and DDE earthquake accelerations for the platforms
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was taken as 2/3 of the ZPA values from the horizontal ground motion spectra.
The response of the annulus structure to horizontal input was reviewed by using analytical models of each' main elevation. The natural frequencies of each elevation were evaluated and compared with the 20-Hz proposed criterion.
If any of these frequencies had been below 20 Hz, appropriate modifications would have been made to increase these frequencies to above 20 Hz.
No additional acceleration response spectra were generated for structural models with fundamental frequencies above 20 Hz.
The horizontal acceleration response spectra developed in a separate analysis of the internal concrete structure are considered applicable for the horizontal analyses of subsystems attached to the various annulus steel elevations.
4.2.1.6.2 Member Evaluation The annulus structure was modeled for equivalent static structural evaluation using the STRUDL computer program.
Each main elevation is modeled as a braced frame continuous structure based on the as-built conditions determined by field inspection. The models of each section are loaded with the pipe, equipment, gravity loads, and the appropriate seismic factors.
The frames are then statically analyzed for displacement, stresses, and forces.
Special emphasis is placed on evaluation of the " frame members and connections for the effects of torsional and lateral loads introduced by the piping systems.
The average yield strength of steel, not to exceed 70% of the corresponding ultimate strength and the average 28-or 60-day concrete cylinder strength of the in place materials, is used in lieu of the specified minimum properties for load combinations including Hosgri seismic.
For load combinations involving 07/14/83 6
DIABLO CANYON SER 4.2.1 i
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DE and DDE, the specified minimum material properties are used.
Normal working stresses without.the customary 1/3 increase for seismic loads are used when the load combinations include DE' For load combinations which include Hosgri or DDE, the working stresses applicable to the operating condition are
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increased by a factor of 1.7.
i The reverification program for the annulus structure shows that the structure withstands all applied loads and loading combinations, and remains within the design limits after modification.
4.2.1.7 Staff Evaluation i
4.2.1.7.1 IDVP Work The IDVP performed field walkdowns of the annulus structure, reviewed the 1981/1982 URS/Blume five frame model, reviewed the Brookhaven analysis, and performed simple one and two degree-of-freedom lumped mass models to confi,rm tangential beam flexibility. As part of the verification of the corrective action work of the DCP, the IDVP selectively reviewed four analysis files. The IDVP has not completed their review of the DCP corrective work as of July 13,.
1983.
Additional review is planned by the IDVP and the final conclusion will be contained in forthcoming ITRs 50 and 51.
The staff finds that the IDVP reviews of the PG&E original analysis and the subsequent analyses by various parties have been professional and well executed.
These reviews have led to modifications of the steel structure in order to retain the qualification of the various equipment attached to or supported by the annulus structure.
It is noted, however, that while the use of free hand averaging of peaks and valleys was previously acceptable by the staff, the smoothed curve should be a reasonable average but not a lower bound. Also, the use of it should be limited to frequencies away from structural frequencies (peaks of the curve). The review is not yet complete.
The staff feels that if the reviews of the remainder of the annulus structure analysis and physical modifications are of the same caliber as the past reviews, then the annulus structure would be acceptable.
However, the staff will have to review ITRs 50 and 51 before a conclusion can be reached.
07/14/83 7
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4.2.1.7.2 DCP Work 4
The DCP review consisted of reviewing the previous seismic models for as-built conditions.
Modifications were made to the frame models to incorporate the effects of the tangential beams for the vertical direction.
The entire floor was modeled for the horizontal direction and the resulting frequencies and mode shapes were used to evaluate the structure against a 20-Hz minimum frequency for individual members. When a member fell below the 20 Hz cut-off frequency, the member was modified to produce a frequency of at least 20 Hz.
The members in each floor were evaluated for the various loads that would be imposed on them using the load combinations from the FSAR.
The DCP concludes the annulus structure can withstand all applied loads and load combinations.
It is noted, however, that a frequency of 20 Hz should not be considered as a frequency in the rigid range without verification.
The Newmark Hosgri spectra approach to ZPA at 33 Hz.
It is the staff's position that the use of 20 Hz and the cut-off frequency for generation of floor response spectra should be verified and/or justified.
The staff finds the DCP reverification to be extensive and professionally executed. With the exception noted above, the results should lead to the acceptance of the annulus steel structure if the program was carried out properly.
The review of the IDVP will verify the accuracy of the DCP program.
The staff will reach its conclusion after the review of the IDVP ITRs 50 and 51.
4.2.1.8 Conclusion The review of the IDVP is not complete at this time.
Additional informatio.n will be submitted at a later date.
The staff considers the 20 Hz cut-off frequency for generation of floor response spectra as an open issue and
~
requests that the IDVP reviews verifications and/or justifications provided by the Project and include the results of review in its future reports.
Upon receiving and reviewing the information described above, the staff can then formulate its final conclusion at that time.
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4.2.2 Containment' Interior Structure 4.2.2.1 Introduction The containment interior structure consists of three major components, the crane wall, reactor cavity wall, and fuel transfer canal. The 106 foot outside. diameter crane wall is 3 feet thick, and it extends vertically from the base slab at elevation 91 feet to the operating floor at elevation 140 feet. The polar crane is supported on the crane wall at elevation 140 feet. The wall also serves as a support for the annulus platforms interior platforms, and floor slabs. The area inside the c~rane wall houses the steam generators, the recirculation pumps, the pressurizer and related equipment. This area acts as a barrier to missiles and jet impingement forces produced by postulated pipe rupture.
The crane wall also helps to support the ends of the fuel transfer canal, the steam generator shield walls, and other structures above elevation 140 ft.
The reactor cavity wall, which is at the center of the containwent building, encloses and supports the reactor vessel. This circular concrete wall has an outside diameter of 34 ft., varies in thickness from 3.5 to 8.5 ft, and extends from the base mat at elevation 91 ft to the top of the floor slab of the fuel transfer canal at elevation 114 ft.
The fuel transfer canal is a reinforced concrete box with an open top, supported at the ends by projections from the circular crane wall and at the center by the reactor cavity wall. The interior surface of the canal is lined with stainless steel plate. The canal holds borated water during refueling and fuel transfer operations. The fuel transfer canal interfaces with the fuel transfer tube at the containment wall l
The primary source of data used by the staff in its evaluation are listed below.
1.
The IDVP Diablo Canyon Nuclear Power Plant-Unit 1 Final Report.
2.
The Pacific Gas and Electric Company Phase 1 Final Report Design i
Verification Program.
3.
Technical interchange meetings between the IDVP and PG&E as documented in the staff trip reports.
4.2.2.2 IDVP Review l
The IDVP verification consisted of examining samples of the DCP verification analysis. The details of this analysis is discussed in Section 4.2.3 of this SER.
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The DCP supplied a calculation index which documented the qualification analyses and computer files of record and served as the basis for selection of the IDVP sample of DCP qualification analyses.
The IDVP had a number of open technical meetings with the DCP to discuss the DCP methodology, criteria and analytical results. Major topics in these meetings included the polar crane evaluation and the interior structure floor response spectra generation.
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The IDVP selected a sample of the DCP qualification analyses to assess conformance to licensing criteria, accuracy of calculations, and the essential steps of the qualification process. A design review checklist was developed by the IDVP to ensure that all necessary items were examined and documented.
In addition to the checklist, the IDVP design _
review included assessments of the completeness, applicability, and consistency of the DCP review and reanalysis methodology.
l The IDVP chose the following areas of the containment interior structure for review.
1.
Reactor cavity wall member evaluation considering compartment pressure, reactor vessel seismic loads, etc.
2.
Reactor ring support evaluation 3.
Polar crane-dynamic solution and member evaluation. This includes evaluation of the main crane components such as bridge girder, crane legs, guide struts, and rail capacity.
i OneE01(1009) was issued by the IDVP as a result of this verification.
The E01 dealt with non availability of floor response spectra above the
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elevation 140 feet floor. Since the DCP was reanalyzing the containment, this E0I was combined into E01 1014 for tracking purposes.
No additional E0I's were issued by the IDVP as a result of their review to date.
The verification program intended to be conducted by the IDVP is not yet complete. Based upon the efforts performed to June' 25,1983, the IDVP considers the following aspects of the DCP work to be acceptable and to satisfy the licensing criteria:
1.
The analyses of the containment structure reflected as-built conditions with conservative assumptions incorporated into the analyses. Pressure and temperature were properly applied.
2.
Numerical accuracy of the calculations sampled was satisfactory.
Minor discrepancies were noted in such areas as determination of section properties, but had no significant impact on results.
3.
Analysis and qualification of the reactor cavity wall.
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- The verification effort of the IDVP is not complete however the IDVP considers the following item to be unresolved.
1.
Calculation of interior structure horizontal floor resiponse spectra.
The final conclusions as to the qualification of the containment interior structure and polar crane will be reported by the IDVP in ITR
- 54. This ITR is scheduled for release of a draft for inhouse comments i
on July 15, 1983. Submittal to 'the staff is not scheduled.
~ DCP Evaluation 4.2.3 The horizontal model of the containment for DE and DDE is an axisy' metric finite element model which includes the exterior'shell, l
internal structure, base slab, and rock mass. The exterict shell and the internal structure are coupled by the base slab and the foundation rock elements and thus the model is used for both structures. The vertical DE and DDE vertical analysis was a static analysis using 2/3 of the zero period acceleration of the horizontal ground response spectra.
The horizontal model for the Hosgri event was the same model used for the DE and DDE analysis except a fixed base was used.
In addition, two lumped-mass models are used for torsional response due to geometric and accidental eccentricity. The two models are fixed base and correspond to 5 and 7% accidental. eccentricity, respectively.
The vertical model of the containment internal structure is a lumped mass coupled model including both the concrete internal structure and the annulus steel frames which correspond to the locations of the five fan coolers at elevation 140 ft. The concrete internal structure is l
represented by one leg of each frame. The concrete mass of the interior is lumped at elevations 114 and 140 ft. The steel frames have a comon support at the crane wall and each carries the mass of one fan cooler at elevation 140 ft, plus any additional attached masses at the various i
elevations. This model was d4Yaloped during the original Hosgri l
evaluation, and is used for determining responses in the concrete portion of the internal structure.
The dynamic analyses for the DE and DDE horizontal model used input motion at the model rock boundaries that produced the required response spectra at the rock / base slab interface. The input motion for the Hosgri models both horizontal and vertical was applied directly to the base of the model.
l Dynamic analyses using time-history, modal superposition techniques were performed. These analyses were then used to produce floor spectra for piping and equipment evaluation as well as to supply moments and forces for the structural design. Structural damping values of 2 and 5% in the DE and DDE analyses, respectively, and 7% damping for the foundation rock was used in both analyses. A cut off frequency of 20 Hz was used for all spectra.
containment interior '
For the Hosgri evaluation, structural damping of 7% was used. The horizontal-torsional models account for the actual geometric eccentricity plus an accidental eccentricity equal to either 5 or 7% of the building dimension.' The horizontal motion due to torsional response is combined with the purely horizontal motion on the absolute sum basis for the 5% eccentricity case, and by the SRSS sum for the 7%
eccentricity case. The 5% eccentricity case is found to govern at all radii from the structure centerline.
The vertical response was computed using the coupled internal concrete plus annulus model. There was no amplification for the concrete portion of the structure. A cutoff frequency of 33 Hz is used for all spectra.
The following specific areas are identified and verified:
1.
" Weights of th'e structure and equipment are recalculated based on as-built conditions. The recalculated weights agree well with those used in the analysis.
2.
Section properties and stiffnesses of the models are compared with as-built conditions.
3.
As-built support conditions of major equipment are reviewed to verify that the equipment weights are correctly apportioned in the vertical and horizontal models.
4.
The as-built configuration is reviewed to verify the fixity conditions within the vertical model of the internal structure.
5.
The internal structure above the operating deck at elevation 150 ft is modeled separately and analyzed using the time-history obtained from the primary model analysis.
The DCP performed a comprehensive review of the overall design of the internal concrete structure.
In addition to the dead, live, and seismic loads, the design loads also include loads from the postulated LOCA.
These consist of compartment pressurization, pipe rupture and equipment support sections, jet impingement loads, and missile loads.
1.
Reactor Cavity Wall l
The DDE seismic loads were found to govern over the Hosgri values.
The structure was found to be adequate for the load combinations.
2.
Reactor Support Ring The reactor vessel imparts vertical (downward only) and horizontal loads on the reactor support ring at four locations. The steel support ring and the concrete portion of the cavity well that supports the ring was checked for abnormal loading conditions. The structure was found to be adequate for these loads.
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Other major sections of the internal concrete structure, including the circular crane wall and fuel transfer canal, floor slab at elevation 140, ft, steam generator shield walls, and walls around the pressurizer, were.
included in the review. The results of these reviews indicate no structural elements were above the allowable stress values.
4.2.2.4 Staff Evaluation 4.2.2.4.1 IbVPReview The verification work of the IDVP consisted of a review of selected samples of the DCP evaluation. The results of this review as documented in the IDVP Final Report indicates that the DCP verification effort is on track. However,the results of the IDVP review have not been made avail.able. They staff will be documented in ITR 54 which does not have a scheduled release data. The staff will fully evaluate the IDVP efforts as it becores available.
4.2.2.4.2 DCP Verification The verification analysis by the DCP incorporated an apparently full reanalysis of the containment interior structure including recalculation of seismic loads. Member evaluation were made using the load combinations specified in the FSAR. The staff will render its findings -
on the DCP verification after the IDVP ITR 54 has been reviewed.
4.2.2.5 Conclusion The staff will formulate a conclusion on the containment interior structure verification upon reviewing the IDVP report in the form of ITR 54.
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1 4.2.3 Diablo Canyon - Containment Exterior Shell 4.2.3.1 Introduction The Containment exterior shell consists of a reinforced concrete cylinder,142 feet high, capped with a reinforced concrete hemispherical dome. The cylinder wall is 3 feet 8 inches thick and the dome is 2 feet-8 inches thick. Both have an inside diameter of 140 feet. The base of the containment is a reinforced concrete circular slab 153 feet in diameter and 14 feet 6 inches thick. The inside of the dome, cylinder and base slab is lined with a leaktight membrane of welded steel plate.
The Tiner is 3/81'nch thick on the cylinder wall and dome, with the exception of a 3/4 inch thick liner plate near the bottom of the cylinder wall and 1/4 inch thickness on the base slab. There is a 2 feet thick concrete floor slab on top of the 1/4 inch thick liner plate.
The basemat is poured directly against the underlying rock foundation.
The piping and electrical connections between equipeent inside the containment structure and other parts of the plant are made through leaktight containment penetrations. Other penetrations are the 18 feet 6 inch diameter equipment hatch, the 9 feet 7 inch diameter personnel hatch, the 5 feet 6 inch diameter emergency personnel hatch and the fuel transfer tube.
The primary sources of the data used by the staff in its evaluation are listed below.
- 1. The IDVP Diablo Canyon Nuclear r2wer Plant - Unit 1 Final Report.
- 2. The Pacific Gas. and Electric Company Phase I Final Report Design Verification Program.
- 3. Technical interchange meetings between the IDVP and PG8E as documented in the staff trip reports.
4.2.3.2 IDVP Work The IDVP verification of. the Containment exterior shell consisted of examining, on a sampling basis, analyses for seismic and certain non-seismic loads. The seismic loads were the DE, DDE and Hosgri events while the non-seismic loads were pressure, temperature, pipe reaction, jet impingement, missile, dead and live loads. The details of the IDVP verification will be reported in ITR-54. This report was not available as of July 10; 1983.
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For the containment exterior structure the DCP reviewed and accepted the original seismic analyses. The DCP then used these results and perfonned member evaluation calculations. The DCP perfonned reanaylsis of the equipment hatch region and the base slab /shell junction, as well as the base slab.. The DCP provided the IDVP with a calculation index which documented the qualification analyses and computer files.of record and served as the basis for selection of the IDVP sample of the DCP qualification analyses.
The IDVP conducted a number of technical interchange meetings with the DCP to discuss the DCP methodology, criteria and analytical results.
Major topics at these meetings included, among other containment topics, the qualification of the external shell including the equipment hatch and the shell/ base junction. The IDVP selected a sample of the DCP quali.fication analyses to assess conformance to licensing criteria, accuracy of calculations and the essential steps of the qualification process. The IDVP review included assessments of the completeness, applicability and consistency of the DCP review and reanalysis methodology.
The sample files chosen by the IDVP for review were:
- 1. Seismic analysis (Hosgri) and member evaluation for the containment shell considered as an axisymmetric structure.
- 2. A sample of the computer run results for a specific load combination.
- 3. Base slab /shell junction member evaluation of adjacent slab and shell elements, steel meridional soldier beams, rebar, etc.
No E01's were issued as a result of the review of the DCP verification work, however the IDVP issued one E01 against-the contaiment exterior as a result of their initial investigation at the beginning of the IDVP effort. This E0I (1014) is classified as Error Class A or B.
The E0I is still open as it has been combined with several other E0I's that pertain to the entire containment structure.
The verification program by the IDVP is not complete as of June 25, 1983.
However, the IDVP considered the following aspects of the DCP work to be acceptable and to satisfy the licensing criteria.
- 1. The analyses of the containment structure reflected as-built conditions with conservative assumptions incorporated into the analyses.
Pressure and temperature loadings were properly applied.
- 2. Numerical accuracy of the calculations sampled was
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satisfactory. Minor discrepancies were noted in such areas as determination of section properties, but had no significant impact on results.
- 3. Analysis and qualification of containment exterior shell under various load combinations, as given in the FSAR and Hosgri report, except in the vicinity of the equipment hatch.
The IDVP considers the following aspects of the DCP work to be unresolved issues at this time.
- 1. Analysis and qualification of the-containment shell in the vicinity of the equipment hatch.
4.2.3.3 DCP Work The DCP reviewed the previous Hosgri, DE and DDE seismic models to assure the models represented the as-built conditions. Based on this review, new model properties of the annulus structure were developed and used for reanalysis. The previous Hosgri seismic model was a fixed base finite element model of the entire containment. This model contained i
the exterior shell and the interior structure of the containment but were uncoupled. The seismic model used for the DE and DDE analysis was also a finite element model but included the base rock. This model couples the exterior shell and the interior structure through the base slab and the foundation rock elements and thus was used for the analysis of both the structures. The model for the Hosgri evaluation considered l-5 and 7% accidental eccentricity. These models satisfied the licensing criteria as contained in the FSAR.
l The seismic loads in combination with other loads as specified in the L
FSAR load combination equations were used as the input to a concrete anaylsis program to determine the local structural forces. Six typical representative sections were selected for review. These sections represented the dome, upper transition zone between the dome and cylindrical wall, the spring line, the mid-height of the cylindrical wall and the bottom of the cylindrical wall. The calculated stresses in the liner plate, rebars and concrete were tabulated and compared to the allowables. The stresses were determined to be within the allowable limits.
The connection between the containment exterior shell and the base slab was evaluated. The connection was designed to allow free relative i
rotation in any meridional plane while resisting meridional membrane forces and transverse shear. The evaluation of various structural elements in this region was performed by an axisymmetric finite-element model.
. An approximate hand calculation of the equipwent hatch region indicated
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the need for additional analysis. A horizontal 90 degree sector by 60
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-4 feet high section of the shell was modeled. The model was symmetric about the hatch center line both horizontally and vertically. The loads considered consisted of the dead load, internal pressure, thermal gradient and two components of the horizontal seismic forces in combination with the vertical. Stresses were obtained as selected points for comparison and isostress plots were obtained to show the stress variations around the hatch opening. Local yielding was observed in relative small areas of the steel plates around the opening for factored load combinations. The computed stresses closely matched the values obtained from measurements made during the structural integrity tests.
The verification of the liner plate system consisted of the development of allowable loads for attachment threaded studs to qualify the mechanical or piping system. The load transfer mechanism fran the external mechanical loads through the liner plate to the concrete stud system was developed to ensure the transfer of all loads into the concrete shell with all elements remajning elastic while maintaining a leaktight boundry.
The DCP analysis verification process identified and verified the following specific areas.
- 1. Weights of the structure and equipment are recalculated based on as-built conditions.
- 2. Section properties and stiffnesses of the models are compared with as-built conditions.-
- 3. The as-built support conditions of major equipment are reviewed to verify that the equipment weights are correctly apportioned in the vertical ahd horizontal models.
The results of the DCP for the containment exterior shell analysis are as follows:
1.
The calculated stresses in the global containment exterior mcdel for the liner plate, rebars and concrete are within allowables.and, therefore, acceptable.
2.
The calculated stresses in the area of rhe exterior shell and base mat connection are less than allowables, therefore, acceptable.
3.
Local yielding was observed in relative small areas of the equipment hatch hexagonal plate adjacent to the penetration sleeve for the factored load combinations. Local yielding is allowed in Part 2 of the AISC. The equipment hatch is, therefore, acceptable.
4.2.3.4 Staff Evaluation _
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The staff agrees that a sample of the DCP work is sufficient for the IDVP to evaluate the DCP work.
It is noted, however, that the design code for containment penetrations accepted in the original licensing documents was the ASME,Section III code as indicated in Table 3.2-4 of the FSAR.
In addition the IDVP should evaluate the justification for the local yielding of the steel plates around the opening. The staff will perform further evaluation of the IDVP effort when ITR 54 bacomes available. cannot' offer further evaluation of the IDVP effort.
4.2.3.4.2 DCP Work The DCP verification work consisted of a review of the models for reflection of as-built conditions, comparison of analytical results and assessments, of the calculated stresses against allowables. The containment shell was evaluated in several places for the global modal, the shell base mat junction and the shell area around the equipment hatch.-
The staff agrees that the procedures used thus far should lead to qualification of the shell but the use of AISC ccde for containment 4
penetration analysis and local yielding of steel plates should be justified.
4.2.3.5 Conclusion The staff will formulate its conclusion regarding the acceptance of the containment exterior shell after the review of the forthcoming IDVP ITR-54 is completed.
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- s 4.2.4 Diablo Canyon - Auxiliary Building-4.2.4.1 Introduction The Auxiliary Building is a reinforced concrete shear wall structure with a steel. framed enclosure over the fuel ' handling area. The fuel handling building is discussed in section 4.2.5.
The building is essentially the shape of the letter "T" with the ster. oriented in the East-West direction and the top of the T oriented in the North-South direction. The containments for Unit 1 and Unit 2 are located on either side of the stem. The building is approximately 500 feet North-South by 230 feet East-West and 90 feet high. The steel frame portion over the fuel handling area is 48 feet tall. The building is founded on the underlying rock and soil material at three different levels. The stem of the T is founded on bedrock at elevation 55 feet. The area between the stem to outside the spent fuel pool is founded on competent rock at n
elevation 82 feet. The area outside the spent fuel pool is founded on compacted soil at elevation 97 feet. The interior. of the structure contains many shear walls that do not form a consistent pattern throughout the height of the structure. The building contains major horizontal floor slabs at 6 different elevations.
The primary scurces of data used by the staff in its evaluation of the verification of the Auxiliary Building are listed below.
1.
IDVP evaluation documented in their Interim Technical Report (ITR) No. 6.
2.
IDVP Diablo Canyon Nuclear Power Plant - Unit 1 Final Report.
3.
The Pacific Gas and Electric Company Phase I Final Report Design Verification Program.
4.
Technical interchange meetings between the IDVP and PG8E as documented in the staff trip reports.
4.2.4.2 IDVP Work-The results o'f the IDVP review of the Auxiliary Building is dccumented in ITR 6 and the IDVP final report. The auxiliary Building was choser, by the IDVP as the initial structures sample for the following reasons.
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The building contains the largest amount of safe shutdown piping, equipment and components.
i 2.
The building itself supports the Fuel Handling Building and the Control Room.
3.
The building is structurally complex with both concrete shear walls and steel framing.
4.
There was a controversy between PG8E and URS/Blume regarding masses in the seismic model of the building during the 1977 analysis.
The scope of the IDVP review, as outlined in ITR 6 is as follows.
1.
Review the URS/Blume horizontal models for the seismic analysis of the auxiliary and fuel handling buildings.
2.
Calculate and compare the building properties for the horizontal models.
3.
Calculate and compare natural frequencies and mode of vibration for the horizontal models.
The IDVP review of the Auxiliary Building seismic analysis revealed that, although the structure had been modified between 1971 and 1977 the same model was used for three sets of analyses in 1971, 1977 and 1979. -
The 1977 analysis nad omitted the soil spring in the N-S direction model. This oversight was corrected in the 1979 analysis. The IDVP used the same model (6 lumped masses on a cantilever beam) as in the original analysis but recalculated the model properties based on the drawings that existed in the PG8E files. Changes were made to model properties in the area of the fuel handling building to reflect the modifications made to the steel structure.
As a result of the IDVP analysis the following concerns were identified.
I 1.
The methodology used to calculate the bending moments of inertia in the design analysis was different from that used in the independent analysis. The resulting bending moments of inertia differ by more than the 15% trigger level used by the IDVP. The effect of this difference on important building periods is from 6% to 15%.
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(fuel handling building stiffness, torsional rigidity of member 2, and centers of mass) l and discrepancies between field and analyzed conditions suggest that design control measures were inadequate.
3.
Differences in the calculated value's for soil springs were reported which have not been reconciled.
Sensitivity studies indicate that the effects of variation of this parameter on important building periods is from 6% to 12%.
A total of 16 E0I's were issued by the IDVP against the Auxiliary Building. Six of the E0I's were for the Fuel Handling Building and will be addressed in se~ction 4.2.5 of this report. Only one of the remaining ten E01's was classified as error A or B, E0I 1097. The E0I had to co with the non-availability of the floor response spectra for the Fan / Machine room above elevation 163 feet. Since the DCP was completely reanalyzing the Auxiliary Building the E01 was combined with several others and will be closed upon the IDVP review of the DCP reanalysis.
4.2.4.3 DCP Work The DCP reanalyzed the Auxiliary Building for the Hosgri event as well l
as the DE and DDE. The geometry of the models used to describe the seismic response of the 1:uxiliary Building are the same as that used for the original seismic analyses. The model was the lumped mass type utilizing six concentrated masses. However, the parameters of the model which described the structure were redefined during the reanalyses to reflect the building as-built conditions. The model possesses displacement and rotation degrees of freedom at each node point for the horizontal direction while only the vertical displacement is retained as a degree of freedom for the vertical model. ' Soil springs are used in.
the horizontal models to represent soil / structure interaction effects for those portions of the structure which are not founded on rock, In response to the staff and its consultants concern regarding the ficar slab flexibility the slabs in the building were surveyed using a thickness and span criteria to determine the natural frecuency. This survey resulted in findings that 12 of the slabs were fle'xible in the i
vertical direction (frequency less than 33 Hz). Detailed finite element models of these slabs using plate elements was made and a time history analysis of the individual slabs were perfonned to generate response spectra at critical locations in the slab. The time history input to the slab model was the output from the closest point in the six mass lumped parameter asdel of the entire building. Significant spectral amplifications were found in these slabs.
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'A structural evaluation of the slabs and walls for significant loadings was made. The loadings considered were the seismic, dead aed live loads. Original criteria of acceptance was taken from the ACI Code 318-63 and SEAOC code 1974 for slabs and walls respectively.
For the current evaluation new criteria for shear walls was developed and used.
This criteria is contained in Appendix 2a of the DCP final report.
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This criteria. considers the following three pcssible failure inodes: (1) exceedance of the shear friction allowable, (2) exceedance of the 8
diagonal shear cracking allowable or (3) the exceedance of the flexural reinforcing stress allowable. Out of plane loads are not combined with the in-plane loads if the out of plane loads are less than 85% of the in-plane capacity.
Loads are distributed from the six mass model to the floor slabs based on the rigid diaphragm assumption. The loads from the walls above the diaphragm (floor slabs), the inertial loading in the slab and the loads in the walls below the slab must be in equilibrium. These loads in turn are used to calculate the shears and moments in the slabs. The shear i
forces in the walls are detennined by the relative stiffnesses of the
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walls in a particular floo'r.
l All of the slabs and walls are found to be acceptable by the DCP. The l
1 slabs were found to have factors of safety of 1.0 to 1.4 for the DE,1.4 to 2.2 for the DDE and 1.1 to 2.0 for the Hosgri earthquake. The j
acceptance criteria was the ACI 318-63 code. The factors of safety for the walls were found to be 2.1 to 3.0 for the DE, 1.8 to_2.8 for the DDE and 1.1 to 1.9 for the Hosgri earthquake. The acceptance criteria was i
the ACI 318-77 code with modifications as descrived in Appendix 2a to
- t the DCP Phase I Final Report.
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The horizontal load capacity of the floor slabs was shown to have a value greater than the demand of the following capacity / demand ratio of 1.04 as a Jow to 3.4 as a high except for one section which had a ratio of 0.45. This ratio indicates that for the loads calculated, the slab i
is 'overstressed in this area. The DCP cited the assumption of rigid diaphragm behavior for the seismic model and simultaneous occurrence of
~aximum forces due to translation and torsion at each level. The m
rationale for acceptance by the DCP is the maximum forces do not occur i
at the same instant in time and the structure is capable of redistritsuting the loads to less heavily loaded sections since the 4
structure is ductile and the demand on the entire section is less than the total section capacity.
l During technical interchange meetings between the IDVP, DCP and the NRC staff several concerns were raised regarding the analysis of the 4
Auxiliary Building. Concern has been expressed over the appropriateness i
of the six mass model used to represent the structure in the seismic analysis.
In particular, the model is based on the assumption that the floor slabs (diaphragns) are rigid in their own plane (the horizontal l
direction) as compared with the walls stiffness in the horizontal direction. The DCP has verbally reported on sieveral studies directed at this issue in technical interchange meetings between the IDVP and DCP.
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In one of tilese studies, a three stick mocal was' generated which ine10ded floor slab flexibility in the vicinity of tne spent fuel pool.
Yte DCP performed a parametric study with the slab flexibility varied
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from rigid thru actual to zero. The results of this DCP study indicated that the f1cer slab flerib511ty did rot htve a significant effect on the structural re3 pense. A second study reported by the DCP involved a complex three dimensional inodel cf the AuAlliary Building using plate elements to describe the floor slabs and inter: connecting walls. The stated purpo1e of this model was to chtain a better distribution of the floor loedings between the yarious floor slebs.
Another 16pic discussed at' many of tha technical interchange meetings was the soil springs used to model the ccnr.setien of the bili 1 ding foundatica to the soil et Sleyation 169 f(et. Questions had arisen regarding the soil properties used to evaluate the springs that were used ~1n the general nedels. The GCF had performed parametric studies that fndicated the respense of the building to the earthquake was not significantly effected by varifticus In these springs for a range of possi.blo values. Ths IDVP en,tha other hand had a' Iso performed parametri: studies for the same probleo which led to results that contradicteo the results of the DCP.
4
_taff Evaluation 4.2.4.4 S
4.2.4.4 1 IDfP Muri The timited ingspendent seismic analysis by the IOVP pointed out several areas of con:ern abnut the PG5E Nc6gri scispic analysis. The results of tna.lDVP analysis was 4cccmented in ITR No. 6 This report was evaluated by the stsff and an sudit cf the backgrcund material was conducted on October 27 and 28,1982. Tne staff generally agreed with e
the analysis but a couple 6f a ee.s were found to b; questionable. The staff fcund that:
(1) The usa of horizontal half spats soil spring formulation
' to compute the soil spri~ngs for the embedment effects was insppropriate.
(2) The method of. incorporating the shear valls inte the moment of inertia talculations was not consistent with the assumptions of the seismic mode).
(3) The soil d3ta used in the anciysis should be verified.
The results of the IDVP evaluation of the DCP reanalysis is not yst J
available.
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4.2.4.4.2 DCP Work The staff finds that the seismic analysis re-evaluation of the Auxiliary Building by the DCP was in general well done and should produce reliable results. The parametric studies presented at the technical interchange meetings, although not formally documented, gave insight into the sensitivity of the various parameters used in the seismic analysis.
The acceptance criteria used by the staff to evaluate the work of the DCP is contained in the F5AR and the Hosgri amendment to the FSAR.
The staff finds the following areas need to be resolved:
(1) The seismic model used by the DCP to predict the structural loads and produce the floor response spectra to be of the generally accepted type for normal seismic analysis.
However, the model has many simplifications and inherent assumpticos. One assumption is that the floor slabs are rigid as compared to the walls.
If floor slab flexibilities are to be used as justification for-accepting an overstress condition then these flexibilities should be incorporated intc the dynamic model used to predict the structural loadings or show the flexibilities to be unimportant.
(2) The use of different versions of the ACI 318 code for evaluation of the floor slabs and walls is not appropriate.
The versions ACI 318-63 and ACI 318-77 are not the versions committed in the Hosgri evaluation criteria outlined in the FSAR. The use of the different versions of the code and the modifications to the 1977 cede as described in Appendix 2a to l
the DCP Phase I Final Peport should be justified by the DCP and evaluated by the IDilP.
(3) The discrepancy between the IDVP and the DCP sensitivity study of the soil spring influence on the seismic response should be reconciled, Also the values of the soil properties should be resolved.
4.2.4.5 Conclusion l
The staff concludes that the investigations by the IDVP were sufficient to illuminate deficiencies in the qualification of the Auxiliary i
Building.
The IDVP. evaluation cf the DCP reverification analysis is not available at this time for staff review and coinnent. However, based on the in-formation presented by the DCP in the PG8E Design Verification Program Phase I final Report, the staff has listed three concerns that should be
,eddressed before the Auxiliary Building is considered acceptable. The l
staff also requires that the DCP formally documents all the parametric l
studies perfonned and used to demonstrate the adequacy of its l
assuir.pticns on slab flexibility and the soil springs.
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N 4.2.5 Diablo Canyon - Fuel Handlino Building 4.2.5.1 Introduction The Fuel Handling Building is a seismic Class I steel f.rsined structure supported on the eastern portion of the Auxiitary Bailding et the elevation 140 feet floor slab. Th6 steel frame supports a fee'l bandling bridge crane (capacity of 125 tens), ar. auxiliary crane (caoacity 'cf 125 tons) and houses areas related to the fuel pool. The steel frtne measures 366 feet long by 58 feet wide and 48 feet high. The steel structure is the mill building type with cross braced columns in the north-south direction and moment resistant frames in the east-west direction. A portion of the end frames are a'nchered on top of a 24 feet high concrete wall comon with the exhaust fare rcoms in the Auxiliary Building. The roof is a trussed and cross braced diaphragm covered 'with metal decking and built up roofing.
Since the structure is de ignated as seismic Class I it must be cualified for all seismic events. Therefore, the structure f.s evaluated for the DE, CDE, and Hosgri events in combir5ation with other loadings as required by the FSAR comitments.
The primary source of the data used by the staff in its evaluaticn are listed beltwt 1.
The IDVP evt.luation as documented in their Interie Technical Report (ITR) No. 6.
2.
The IDVP Diab'Ic Canyon Nuclear Fower Plant - Unit 1 Final Report.
3.
The Pacific Gas and Electric Corcany Phase I Final Report Design Verification Prcgram.
4.
Technical interchange meetings between the ID M and 'PG5E as occumented in the staff trip reports.
4.2.5.2 IDVP Wark e
The IDVP verification of tne Fuel Handling Building consisted of DCP analysis for both the seismic and examining on a"strnpling basis the. loped a design review checklist of the l
non-seismic loads, The IDVP deve items to be examined and dccument.ed the results. The review included assessments of the completeness, apolicability, and consistency of the I
j DCP review and reantlysis nethodology. T1e IDVP performed hand calculations where necessaty to assess the effects af various DCP ass m ptions and calculations. The IDVP did not perfom a separate analysis of the fuel Handling Suil6ing.
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. 4 The sc7.ples reviewed by the IDVP were:
1.
Methedr;1cgy end procedums used it; t.1e for,nralatiori of the dynamic and eq'.iivahnt static foodels.
P, Geometry ano m6nder properties used in the models.
3.
f?ca vibratlon enaiysis of tne dynamic models to detzrmine dynamic characteristics, 4.
Tisw hir. tor,y analyses (5tsgrl) of the dynamic mo;iels wnich produced respnse spectra a?d pr6vided c:celerations for use in t1e equivalent static M del ir.cluaing the input tilne history from elevation 140 feet of tne auxiliary htlid?ng..
ii. Eva'luaCon cf the nodal occelarations used to determitte equivalent static loads.
6.
Computatior of loads for the Equivalent static an:alysis and a sampia of the computer ruf.s fot a Static analysis iosd case.
7.
Comparison of selected member leads with niellter allcwable loads for the postula'ted Hosgri ever.t, The IDVP sElecttd sam 91e covered approxiteately 50'4 cf the structural dyeamic analyses, trie static enalysis and memter evoluction. Th.e crane l
was not included ir the dynamic shalysis simple. The IDVP did not l
review the pre;iairacy static model the DCP used in the Intlysis te l
determine the mcdification requirtsnents. No E01's were issue ( for the l
Fuel Handling Bui;oin.) with ecoard to the DCP corrcctive action orogram.
l Six E0I's wtre (ssued cs a result of the original IDVP evaluation cf the Fuel Handling Buildtng. Five EDI's were classified as 6rrer class A.
All of the E0I's pertcin tc differences MEtwebn thf design drawings a~d
?he as-built configuration, Fcur of the E01's were combineo fr.t6 the remaining E0I 1092 and will be chsad by the IDVP fir.nl verification of the assbuilt structure.
l l
Tne verification progra:r. conducted by the IDVP is noi. complete as of I
July 7, 1933. However, the IOVP considers some portions 'af tha DCP work accept 3ble and satisfies the licensing criteria. Th6se portions are listed below. The 1DVP will formulate their final ccnclusiprs when the i
l DCP. modifications and !0VP fielo walktwns for verificaticns of ?.be ts-built t;onditiors against designs are completa.
The IDVP report will be issued as ITR 57.
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The IDVP finds the following iteins acceptable at this time.
j 1.
Omission of an allewance for accidental eccentricity in the Fuel Handling Building because the torsional effects are-
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accounted for in the auxiliary building rr.sponse at elev& tion 140 feet.
2.
The. ranges of crene locations and assessment of their effects upon results.
3.
The dynamic models used in the Fuel Hatidling Building evaluation.
4.
Response spectra generatior).
~5.
Equivalent static loads detamined from the dynamic acceleration profiles.
6.
Qualification of members and connections.
l 4.2.5,3 DCP Work The DCP perfonned a complete seismic analysis of the Fuel Handling Suilding and crane using the critaria contained in Section 3.0 of the l
FSAR for DE shd DDE loads. The evaluation for the Hosgri event used the criteria co'ntained in Sections 4.1 and 4.3 of the Hosgri Report.
t 1he OCP did a preliminary review of the Fuel Handling Building which consisted of a. field investigation of as-built conditions, review of the app!icable criteria and a simpitfied analysis of selected portions of the structure. This review indicated the previous analyses had not produced conserystive results. Given this condition the DCP developed i
more cetailed models and performed a structural evaluation.
i Three finite element models were used to perfom the analyses of the Fuel Hendling Building, Each of the models is made up of three dimensional beam / truss elements having up to six degrees of freedom per joint. The materials used for the Hosgri analyses are based on as-built inatsrial prope.rties. The computer solutions for each of the models was obtained utir.g the STARDYNE computer prcgram.
The first iedel was a complete model of the entire structure and was t
used to perfom static analyses. Staticloads(e.g.,craneloads)are input directly to this model to obtain meneer loads. Equivalent i
l fnertial loads were input to this model to obtain seismic induced member stresses.
The magnitude of the inertial loadings was obtained from the detailed dynamic analyses perfonned with the second and third models.
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4 The second and third models were generated to perfom the seismic response calculations. One of these, models the end six bays of the 18 bay structure while the other.models the middle six bays of the structure.
For each of these models the dynamic degrees of freedom (DDOF) were specified and a time history analysis of the seismic response of the structure was performed. About 20 DDOF were used for the horizontal analyses while 31 DDOF were.specified for the vertical analyses. The input time history is obtained as the output from the seismic analysis of the Auxiliary Building at the elevation 140 feet
. level. Several analyses were perfomed for the Auxiliary Building with varying ec,centricities. The time history having the largest content at the frequ~ency ranges of interest to the Fuel Handling Building is selected for these analyses. Output fr6c these analyses consists of floor response spectra at locations of interest and global accelerations which were used to. generate the equivalent inertial loading to be applied to the first model so that member seismic forces could be determined.
The results of this analysis indicated certain structural modifications were needed in order to meet the acceptance criteria contained in the FSAR. After the modifications were designed the structural models were modified to reflect the structural changes and the analysis redone. The members were then either re-evaluated or it was shown that the member j
loads decreased as a result of the design modification. All members i
were shown to satisfy the acceptance criteria. The modifications i
generally involved the stiffening of most bracing systems and i
strengthening of connections to meet the acceptance criteria when larger loads were applied.
i e
i During the technical interchange meetings between the IDVP, DCP and the Auxiliary Building analysis as' sed regarding the use of output from the NRC staff, concerns were expres input to the base of the Fuel Handling Building. The output from the Auxiliary Building analyses consists of a translation component plus the rotational component times the distance from the center of rotation of the Auxiliary Building to the point of application on the Fuel Handling Building. Uncertainties exist because of the large dimensions' of each of the structures. The DCP reported, based on parametric studies, that their treatment of this l
program was adequate. These studies are not contained in the DCP Phase I report.
4.2.5.4 Staff Evaluation i
l 4.2.5.4.1 IDVP Work The IDVP sampling of the Fuel Handling Building was sufficient to uncover inconsistencies in the structural analysis-and execution of the design. Although the IDVP did not perform an independent design analysis the hand calculations were sufficient to highlight areas of concern. The field verification of the design against the as-built structure was sufficient to show deficiencies in the structure as i
evidenced in the interim technical reports and IDVP Final Report.
4
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- The verification work of the IDVP is not complete as yet in the Fuel Handling Building as. modifications and minor reanalysis is still in progress by the DCP. The IDVP is currently reviewing the DCP calculation o
packages and will publish an ' Interim Technical Report 57 when this review work is finished and the field verification is completed.
j l
4.2.5.4.2 DCP Work I
The re-evaluation work'by the DCP consisted of a complete analysis of the existing Fuel Handling Building structure. The re-evalu included field verification of the existing structural confi.ationguration, generating a detailed computer model of the structure, perfoming a dynamic and static analysis and performing member evaluations.
If modifications were determined to be necessary these modifications were made and the structure re-evaluated with the computer model changed to refle~ct these modifications. This procedure is judged sufficient to yield acceptable results.
The staff finds that the following items need to be addressed by the DCP as they reflect on the quality of the results of the Fuel Handling Building analysis.
1.
The use of the translational and torsional response of the i
Auxiliary Building as input to the base of the Fuel Handling Building must be documented more completely in the Phase I 1
report.
If parametric studies are available to demonstrate the validity of the DCP approach they should be included in l
the report.
J 2.
The tbtal number of degrees of freedom contained in the dynamic models were reduced to 20 to 30 degrees of freedom prior to performing the dynamic analyses. Some recent studies have indicated that this dynamic reduction often results in serious errors particularly with regard to member loads. The particular set of dynamic degrees of freedom selected for the models should be justified.
4 l
4.2.5.5 Ccnclusion The staff concludes that the investigations by the IDVP were sufficient to highlight the important areas of concern about the structure qualification and produce satisfactory results thus far, except for the omission of an allowance for accidental eccentricity. The applicability of the Auxiliary Building elevation 140 feet floor slab motions input to-the Fuel Handling Building model omitting the accidental torsion should i
be shown thru the use cf parametric studies and evaluated by the IDVP.
l The use of a degree of freedom reduction procedure may not be appropriate and may lead to erroneous member forces in the structure.
i It should be shown by the DCP and evaluated by the IDVP that the use of this reduction method yields correct results.
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1 4.2.6 Diablo Canyon - Intake Structure 4.2.6.1 Introduction The Intake Stiructure is a seismic Class II reinforced concrete structure which housed the seismic Class I Auxiliary Salt Water (ASW) pumps.
Since the structure houses Class I equipment the Class II structure must retain its integrity during a seismic event so that the function of the i
Class I equipment will not be impaired.
The Intake Structure has plan dimensions of approximately 240 feet in the North-South direction and is parallel to the seaward face of the structure and 100 feet in the East-West direction. The strutture is l
backfilled on three sides and open to the water on the fourth. The top deck of the structure is at elevation'-31.5 feet. ~Two ASW pump room concrete ventilation towers and coaxial pipes (snorkels) extend from the top deck to an elevation 49.4 feet. The snorkel pipes provide ventila-i tion to the ASW pump compartment. The top deck is an 18 inch thick slab, with openings provided for equipment removal. The pump deck floor is at elevation -2.1 feet and supports the four main circulating water pumps and the four ASW pumps. The ASW pumps are located in the ventilated watertight compartments.
The primary source of the data used by the staff in its evaluation of the verification of the Intake Structure are listed below.
1.
IDVP Diablo. Canyon Nuclear Power Plant - Unit 1 Final Report.
2.
The Pacific Gas and Electric Company Phase I Final Report Design j
Verification. Program.
l 3.
Technical interchange meetings between the IDVP and PG8E as i
documented in the staff trip reports.
l 4.
Review of detailed DCP engineering calculations of the ventilation l
structure modifications.
The work associated with the soil properties investigations are addressed in Section 4.5 of this SSER.
4.2.6.2 IDVP Work The IDVP verification consisted of field inspections to ensure confromance between design drawings and as-built conditions and review of the PG&E original design calculations for the DE, DDE, and Hosgri i
events. The IDVP did not perfonn separate analyses such as generation of dynamic.models and computing individual member stresses.
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The specific samples chosen by the IDVP for review represent approximately one-third of the DCP qualification analysis and were:
1.
The Hosgri and DE mathematical models. This included generation of response spectra and member loads. The DE model was also used to determine the DDE response spectra.
2.
Member evaluation for the beams, columns, walls and slabs'.
Structural stability was also reviewed with respect to sliding, overturning and soil bearing pressure.
3.
The ventilation structure and snorkels which are part of the ASW seismic Class I system.
During the initial. review three E01's were issued by the IDVP which app 1 fed to the intake structure.
EDI 1022 was error Class A/B and two were not classif.ied. All three were combined together into EDI 1022 which is still open. The E0I's applied to as-build configuration of the crane, discrepancy between the Hosgri report and Blume May 1979 report and the use of inappropriate floor response spectra for the ASW pump seismic input. The verification the IDVP conducted is ' considered complete and the IDVP considers the DCP work as acceptable.
The IDVP will report the results of the DCP corrective action in ITR 58.
Specifically, the IDVP accepts the following:
1.
Qualification analyses reflected the as-built conditions.
2.
Criteria were properly applied. The 10 percent amplification of horizontal response to account for accidental eccentricity was conservative with respect to floor response spectra.
It was not conservative with respect to certain structural members; however, the capacity of these members was sufficient to satisfy properly amplified demands.
3.
Use of fixed base model for the DE/DDE event and the Hosgri event is acceptable.
4.
The dynamic models used were satisfactory.
5.
The response spectra generated were satisfactory.
6.
Structural ~ members including walls and slabs were qualified for the Hosgri event.
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4 7.
The flow straighteners possessed adequate strength using the ductility criteria specified. Walls and Flabs were qualified without the use of ductility considerations.
P 8.
Vent shaft system was shown to be adequate.
On the basis of the above IDVP statements, arrived at.by reviewing the DCP qualification analyses, the IDVP considers the intake structure to be qualified *and meet licensing requirements. However, the sliding, overturning and soil bearing pressure calculations are still under review. The soil review will be addressed in Section 4.5 of this SSER.
4.2.6.3 DCP Work
'In order to address some NRC non-verification concerns about wave forces, from a degraded breakwater, PG8E constructed a three dimensional physical scale model of the cooling water intake basin, intake structure and a hypothetically damaged breakwater to examine the effects of these Wave forces on the structure and its operation. As a result of these scale models tests it became necessary to modify the ventilation system for the ASW pumps to prevent ingestion of water into the pump chambers.
No significant slam pressures were noted from these tests 3nt either the curtain wall or the floor of the pump compartment, provided that the top deck slab was modified. These modifications were a non-structural fillet between the front curtain wall and the underside of the top slab and modification to the forebay access manhole to prevent air leakage.
These modifications will be verified by the IOVP. The DCP also performed the following investigations.
1.
Verify that the spectra generated for the DE, DDE and Hosgri events are adequate for the design of the Class I ASW equipment.
2.
Verify that a gantry crane failure would not impair the Class I ASW systems.
For the seismic studies, two types of analyses were performed to evaluate the structural response of the Intake Structure. These were a time history linear analyses to obtain support point response spectra for the ASW equipment and a model analysis of the structure to determine the structural responses to the earthquake.
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4 4-The gantry crane analysis used the as-built drawings as the basis to generate the seismic mathematical model. The analysis considered the crane in the operating pcsition for both the loaded and unloaded cases.
The crane could not affect the ASW pump systems in the parked position.
l The analysis showed the crane is stable and the members and joint stresses were withir. Allowables.
4.2'.6.4 Staff Evaluation 4.2.6.4.1 IDVP Work t
The IDVP work consisted of field verificatiorrof the as-built structural configuration against the design drawings, a review of the PGSE original calculations and a review of the DCP verification calculations of the ventilation modifications. The initial review by the IDVP revealed the inappropriate use of the floor response spectra for the input motion of the ASW pumps. Tne subsequent review of the DCP evaluation showed the response at the ASW pumps had been correctly determined.
The staff finds the IDVP review adequate to determine the acceptability of the DCP evaluation. The conclusion is based on the material presented in the IDVP Final Report and reinforced by the staff review of the DCP ASW pump ventilation structure modification calculations. The question of the sliding, overturning and soil bearing properties is addressed in Section 4.5 of this SSER.
4.2.6.4.2 DCP Work-The DCP work consisted of a review of the seismic models used for the Hosgri evaluation, modified as necessary to reflect the as-built
- configuration, and the modifications to the ASW pump chambers ventilation system. New response spectra for the ASW pump support were calculated and an evaluation of the structure was perfonned. The assessments of the structure stability against sliding, overturning and foundation bearing capacity are addressed in Section 4.5 of this SSER.
l The staff finds the DCP evaluation of the structural portion of the l
Intake Structure to be acceptable. This conclusion is based on the findings of the IDVP, a review of the material presented in the PG8E I
Design Verification Program Phase I Final Report and an audit of the
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ventilation structure calculations.
4.2.6.5 Conclusion Based en the material presented in the final reports of.both the IDVP and the DCP and the staff audit of the DCP calcualtions of the modifications to the ASW pump chambers ventilation structure the staff finds the structural evaluation of the intake structure acceptable. The questions concerning the sliding, overturning and soil bearing pressures are addressed in Section 4.5 of this SSER.
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4.2.7 Diablo Canyon - Outdoor Water Storage Tanks 4.2.7.1 Introduction The Outdoor Water Storage Tanks (0WST)(consist of four types of tanks:
(1) the refueling water storage tank, 2) firewater / transfer storage tank, (3) condensate tank and (4) primary water storage tank. The tanks are located outside the fuel handling building.
There are two tanks of
~
each type, one to service each unit of the plant except for the firewater / transfer tank. Only one firewater / transfer tank is provided.
The tanks are made of.a steel dome top and a steel cylinder which is anchored to a concrete base. The steel shell and dome have been covered with a reinforced concrete shell. The concrete shell provides protection against the external hazards such as tornado missiles. The firewater /
transfer tank is constructed the same except it is a coaxial tank with the inner cylindrical tank being the firewater tank and the outer portion being the transfer tank. The' inner and outer steel cylinders are connected by a common steel dome roof. All of the tanks are supported on concrete fill down to bedrock and are anchored to the foundation with rock anchors.
The primary sources of the data used by the staff in its evaluation are listed below.
1.
The IDVP evaluation as documented in their Interim Technical Reports (ITR) No. 16 2.-
The IDVP Diablo Canyon Nuclear Power Plant - Unit 1 Final Report.
3.
The Pacific Gas and Electric Compar.y Phase I Final Report Design Verification Program.
4.
Technical interchange meetings between the IDVP and PG8E as documented in the staff trip reports.
4.2.7.2 IDVP Work The IDVP verification of the Outdoor Storage Tanks consisted of selecting one of the tanks verified by the DCP and reviewing this analysis work. The tank selected was the refueling water storage tank (Seismic Class I). The IDVP examined the DCP qualification analyses for all seismic and non-seismic loads. The seismic loads are the DE, DDE and Hosgri events and the associated fluid dynamic forces. The non-seismic loads are pipe reaction, hydrostatic and dead loads.
The IDVP design review included assessments of the completeness, applicability and consistency of the DCP review and reanalysis methodology. Hand calculations were performed by the IDVP, where necessary, to assess the effect of various DCP assumptions and
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2-calculations. Tne conformance with the licensing criteria, the accuracy of calculations and qualification process were also assessed. The i
refueling tank was chosen as the sample tank because it contained modifications for the Hosgri evaluation. Topics reviewed were:
- 1. Conformance of analyses to as-built condition
- 2. Formul,ation of dynamic models
- 3. Consideration of flui' forces under seismic excitation d
- 4. Structural stability - sliding, overturning and soil bearing pressure.
The verification program conducted by the IDVP is con 11dered complete l
and the conclusions the IDVP reached are:
- 1. The qualification analysis was found to be acceptable.
- 2. The dynamic; analyses and results are acceptable.
- 3. Sliding, overturn'ing and soil bearing pressure factors of safety are acceptable.
As a result' of R. L. Cloud's preliminary investigations two E0I's were issued. The subject of these E01's were the transmittal of design information between PG8E and URS/Blume, the subcontractor who performed the analysis. These E0I's are now satisfactorily resolved with ~the verification of the Outdoor Water Storage Tanks by the DCP and reviewed by the IDVP. The IDVP considers the Outdoor Water Storage Tanks to be qualified and to meet the licensing requirements.
4.2.7.3 DCP Work The 3 verification work consisted of performing independent hand calculations for the refueling water storage tank only for the Hosgri event. The results of the hand calculations were compared to the original finite-element analysis for the tanks described in the Hosgri Report. Minor discrepancies were identified between the as-built structural configuration and the original seismic finite-elerent arialysis. Hand calculations were perfomed and the results were compared to the original analysis to assess the significance the differences these variations made on the final results. The effects were minimal and the computed stresses were less than the allowable limits. The tanks were also reviewed for the DE and DDE by perfoming hand calculations using the original Hosgri finite-element analysis as a basis. The computed stresses were less than the allowables. The factor of safety against overturning and sliding for the foundation was computed by the DCP as 1.60. The uplift on the rock anchors was within the allowable capacity of the anchors.
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4.2.7.4 Staff Evaluation 4.2.7.4.1 IDVP Work The IDVP work consisted of reviewing the work of the DCP and performing hand calculations where necessary to assess the effects of various DCP assumptions and calculations. The DCP work reviewed was the comparison of the analyses to as-built conditions, formulation of dynamic models, method of fluid force consideration and structural stability. The IDVP found the analysis of the DCP to be acceptable. The two E0I's issued by R. L. Cloud as a result of the work performed before the DCP evaluation were closed. The E0I's related to the use of correct design information for the Hosgri evaluation.
The staff agrees' with the results of the IDVP structural evaluation of the tanks. However the questions about soil properties raised by the staff in the review of ITR 16 have not been resolved. These items are discussed in section 4.5. of this SSER.
4.2.7.4.2 DCP Work The DCP work consisted of a review of the original analysis for the refueling water storage tank and a limited analysis of the firewater and transfer tank vault opening area. The validity of the original finite-element analysis was confirmed using. hand calculations and iomparing the results to the original analysis. The comparison shows that the hand calculations produced sometimes higher forces and sometires lower forces. However, the forces predicted by either method were less than the capacity of the tank at the particular section being investigated. Some minor discrepancies were identified between the as-built structural configuration and the original seismic finite-element model but were shown to be of minor consequence.
The staff finds the DCP evaluation to be of good quality and would lead to valid conclusions. The staff finds the DCP analysis acceptable.
4.2.7.5 Conclusion Based on the information presented in the Final Reports of both the IDVP and PG8E,the staff concludes that the outdoor water storage storage tanks are acceptable and meet the licensing requirements except for the questions about the soil properties that are address in Section 4.5. of this SSER.
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f 4.3 Piping and Piping Supports 4.3.1 Large Bore Piping and Supports 4.3.1.1 Large Bore Piping The Diablo Canyon Project (DCP) reviewed all Design Class i large diameter piping, except for that analyzed by Westinghouse. Large diameter piping is defined as that having a diameter of 2 1/2 inches or i
greater. Pip 4ng previously analyzed by Westinghouse, which includes the reactor. coolant loop piping, was not reanalyzed by Westinghouse unless there was a revision in input data.
The reanalysis of all large bore piping was performed subject to the criteria described in Section 3.7 and 3.9 of the Diablo Canyon FSAR and Section 8 of the Hosgri Report. These criteria were not changed for purposes of this reanalysis.
For Class 1 piping the load combinations and allowable stresses were used with the applicable piping code, ANSI B31.1-1973 Summer Addenda.
The DCP evaluated pipe stresses resulting from pressure, deadweight, thermal. DE, DDE, and Hosgri events.
For evaluation of the stresses resulting from the Hosgri event, the load combination consisted of pressure, dead weight, and Hosgri seismic loading. Where applicable, hydrodynamic loading has also.been included in the analyses.
Seismic dynamic analyses were performed by the response spectrum modal superposition method, as described in the FSAR. This method uses enveloped horizontal and vertical acceleration building spectra to develop the model loading. Two separate analyses are performed for a given piping structure, consisting of the spectra in the vertical direction and each horizontal direction. The loads from both analyses i
are then enveloped and introduced in the code stress and compared to the applicable stress criterion. Seismic anchor motion resulting from differential building motion or flexible equipment motion was not included in the Hosgri reevaluation, per Hosgri criteria, but was considered for the DE event only.
9 All lines were also reviewed to confirm that the thermal analysis considered the modes of operation defined in the applicable Diablo Canyon Design Criteria Memorandum. Thermal loads were also combined with sustained loads and DE seismic anchor levels to evaluate the resulting stresses per ANSI B31.1.
1Property "ANSI code" (as page type) with input value "ANSI B31.1.</br></br>1" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. For the static and dynamic analysis the piping was reevaluated using as-built configurations as input. These configurations were determined by an onsite walk-down and recording of data such as type and location of supports on the relevant isometric drawings. These drawings were used to develop the models used in the computer analyses.
For the seismic analyses the Blume and Newmark relevant spectra were enveloped.
i However the final PGE Phase 1 report does not indicate which spectra is being used, as the seismic review of a number of buildings is still
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t ongoing, as-per PGE status report of June 24, 1983. These seismic reviews are still open Error and Open Items identified by the IDVP.
The PGE piping reanalysis was done using the Bechtel computer program ME101. The Westinghouse reanalysis was done using the program WESTDYN.
Both programs were accepted by the MEB for their capability to perfom seismic analysis using envelope spectrum modal superposition analysis.
l The output of.the piping analyses included pipe stresses, support loads, equipment loads and valve accelerations.
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4.3.1.2 Large Bore Piping Supports Supports for s'afety related large bore piping were reviewed by the DCP and modified, if necessary, to assure compliance with' the previously accepted criteria listed in the Hosgri Report. This included a review of the design, methodology and documentation. New supports which were added to maintain piping stresses within the piping allowables were also designed to satisfy the same criteria as the existing supports. All supports were required to be designed with a natural frequency of at least 20.Hz in the restrained direction.
[
. Loads resulting from thermal, dead load hydraulic loads and seismic 1
loading were used to review pipe supports. For Hosgri analysis the load combination consisted of dead load plus Hosgri inertia and anchor movement loads. For concrete expansion anchors this combination was augmented by loads resulting from restrained themal expansion. For load combinations including DE and DDE, the load combinations included dead load, hydraulic loads (due to fast valve closure or relief valve thrust) and loads due to restrained thermal expansion and differential
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l
' seismic anchor movement.
l Depending on the Code interface boundary, either ANSI B31.1 or AISC criteria were used as stress and load criteria, previously specified and accepted in the Hosgri report. For qualification of supports by testing the ASME BPV Code, Subsection NF rules for qualification by testing were used where appropriate.
For standard component supports, such as snubbers, springs, rods, etc., the load capacity data sheets or manufacturers reconsnended values were used for allowable loads. For concrete expansion anchors, the allowable loads are those which were developed to comply with the requirements of I&E Bulletin 79-02.
4.3.1.3 Results of the Review and Reanalysis The results of the piping review and reanalysis are shown in two extensive tables: one for piping and supports required for fuel loading. For each piping system the results consist of the following:
1.
maximum stress ratio-maximum actual stress divided by the allowable stress.
2.
allowable stress corresponding to the load case with the maximum stress ratio.
3.
load case with the highest stress ratio 4.
pipe modification, such as rerouting 5.
number of pipe supports i. _. _,.
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3-6.
number of supports modifi' cations 7.
building or structure in/pn which the piping is located. The containment annulus structure is considered as a part of containment and is not listed separately. The fuel handling building is included as a part of the auxiliary building.
In some cases the piping stress analyses are based on preliminary input such as spectra and building displacements, as stated above. PG&E has indicated that controls are in place to assure reconcilation of these analyses and resultant designs with the final input data. These cases are not listed in the tables.-
l Piping and supports required for fuel loading are summarized in Table 2.2.1-3.
A total of 88 piping analyses, or problems, were performed.
Of these 54 were in the Auxiliary / Turbine building, 33 in the Containment building and one in the yard. All stress ratios were. less than one i.e. below allowable.
In most of the analyses the thermal load condition caused the maximum stress ratio. This was probably as a result of the additional stiffening of the piping system which was added to withstand the ~ seismic loading. There were a total of 6 pipe modification which consisted mostly of rerouting or the addition of reinforcing pads at branch connection points. There are 2253 supports in these piping analyses of which 1473 were added or modified in some manner. The most frequent type of modification consisted in the addition ~ of a support or a change in support type. Other types of modification consisted of additions of bracing members, changes in structural shape or other minor changes. No breakdown is shown in this Table by type of modification, nor is the stress or load ratio for the highest loaded support reported.
Piping and supports not required for fuel loading are listed in Table 2.2.1-4.
A total of 171 analyses were performed of which 69 were in the containment b1dg. Again in most of the analyses the thermal load condition caused the maximum stress ratio; all stress ratios were again calculated less than one. There were 10 pipe modifications consisting mainly of rerouting. There are 2303 supports of which 1410 were modified in some manner.
4.3.1.4 Independent Design Verification Program (IDVP) Effort 4.3.1.4.1 Initial Effort The IDVP performed an analysis and review of an initial sample of large bore piping. This analyses was performed by Robert L. Cloud and Associates (RLCA) and reported in the Interim Technical Report (ITR)
- 12.
The initial sample consisted of 10 piping models which were taken from various plant safety related systems.
To obtain a representative sample RLCA reviewed Table 8.3 of the Hosgri report. The general plant walkdown and drawing reviews the ten initial piping samples were chosen considering the location, system, class, intersystem connections, types of valves, and groups which performed the design analysis.
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'. The RLCA effort for the initial sample consisted of the following major tasks:
Field verification and comparison to design isometrics Development of a computer model of each model and an in-dependent Hosgri seismic analysis Comparison of results to the stress or load criteria and to the results of the design analysis Follow-up analysis to reconcile differences, where possible, between the independent verification' analyses and the design analyses i
RLCA field verified each sample problem, starting with the design drawings prepared in response to the NRC I&E Bulletin 79-14. The 2
information which was field verified included: pipe size, location, concentratedweights(valves, flanges,etc.), insulation, vent / drain lines, valves (e.g.,operatororientation), supports (location, type, orientation) and connected equipment.
Based on the design isometrics and the field verification results, RLCA developed a computer program piping model for each sample. Particular consideration was given to modeling boundary conditions and intermediate supports (e.g., whether terminal equipment was rigid or flexible, l
supports were active or inactive (large gaps or one-way supports)), and i
modeling concentrated masses, including centers of gravity of such components as remote operated valves. Once.the model geometry and t
piping properties were formulated, seismic and deadweight loads were defined for each piping sample.
I For, seismic analysis:
Hosgri response acceleration spectra were assembled based on i
.. pipe size and attachment locations.
The damping ratios used were 3% for piping with a nominal diameter greater than 12 inches and 2% for piping with a nominal diameter less than or equal to 12 inches.
The dynamic analysis was performed by the envelope response spectrum method using the NRC verified computer program ADLPIPE.
Two separate analyses were performed in which the dynamic response for each analysis was calculated based on one horizontal plus one vertical input spectra. The response on a modal level from each direction was added by absolute sum.
All modal responses were then combined by SRSS to obtain the final 2-D response. The total response was enveloped from the two separate analyses, one with North-South Horizontal and Vertical Spectra, the other with East-West Horizontal and Vertical Spectra.
The dynamic response considered the greater of either 10 modes or all modes less than 33 Hz, the rigid cutoff frequency.
In addition to seismic loads, sustained loads consi. sting of deadweight and pressure loadings were also evaluated and combined with seismic.
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RLCA compared the results of their independent analyses to both the Hosgri licensing criteria allowables and to the design analyses results.
the Hosgri criteria for piping are based on Equation 12 of ANSI B31.lb-1973. For the comparison of Hosgri stress between the verification analyses and the design analysis (based on the citied 4
equation), RLCA selected the five locations of highest combined stresses or locations where the combined stress exceeded 70% of the allowable.- A comparison of. pipe support loads, nozzle loads, and valve accelerations for the verification and design analyses was also perfonned.
In cases where comparisons of seismic stress or seismic support load results between the verification and design analyses exceeded the 15%
acceptance criteria, RLCA examined the differences through follow-up analyses. The follow-up analyses consisted of making the verification model.,more and more identical to the design model until seismic stresses, loads, and accelerations met or approached the 15% criteria, or until the differences were explainable.
The initial sample effort on large bore piping led to the issuance of 73 E01 (Error /Open Item) files. These were resolved-as follows:
4 Findings (ER/A,ER/AB.ER/B): 7
. Combined with findings:
8 Observations (ER/C, ER/D, PPR/DEV): 41 l
Closed items:
18 Based on these resolutions, RLCA identified eight generic concerns:
I 1.
The PGandE 79-14 design isometrics in several cases do not I
completely reflect the "as-b~uilt" conditions. As a result, the design analyses differed from the "as-built" piping configurations.
2.
The documentation and modeling of remote operated valves in several cases did not reflect the "as-built" conditions.
l 3.
The modeling of attached equipment as in-line components or as I
terminal points, in several cases did not adequately consider l
equipment flexibilities and support conditions.
4.
The design analysis response spectra, in several cases, did not envelope the Hosgri response spectra.
In addition. Hosgri response spectra were not identified for several plant locations / elevations from which Design Class 1 piping is supported.
5.
The tributary pipe mass assigned to support locations in the design analyses in certain cases were not considered in calculating support loads.
6.
Pipe and component (e.g. flanges) weights in the design analyses in i
several cases differed from the vendor supplied values.
'i i
i 7.
In several cases, the design analyses did not consider branch lines and analysis over lap with adjacent systems in an adequate manner.
8.
In several cases, the valve accelerations and equipment nozzle loads exceeded their respective allowable values.
In addition to the eight generic concerns, one specific RLCA concern related to the modeling of standard fittings, such as swage fittings and tees.
In several cases, equivalent pipe properties were not used.
Based on the findings in this initial piping sample the DCP initiated a plan for corrective action of computer analyzed piping which included a complete walkdown and a review of all design analyses. Deficiencies were to be corrected by additional qualification and verification. The IDVP verification program for the PGandE corrective action which is described below was initiated to provide assurance that the above concerns have been addressed.
4.3.1.4.2 Additional Effort Upon completion of the initial sample, RLCA reviewed an additional sample of five more models as specified in ITR-1. These models were selected from piping categories not represented in the initial sample.
The additional models were selected to determine if all concerns ~with computer analyzed piping were identified for inclusion in the DCP Corrective Action Program.
ITR-17 reported the RLCA review of the IDVP additional sample for large bore piping. The additional sample consisted of five piping analyses which were selected considering the following categories of piping not included in the initial sample.
l 1.
Piping connected to primary loop piping analyzed by others.
2.
Computer analyzed field run piping 3.
Design Class 1 subclasses not included in initial sample RLCA used the same analytical procedures and evaluation criteria in the additional sample as were used in the initial sample except follow-up analysis was'not performed where differences in results could be attributed to significant differences in geometry or analytical modeling.
The additional sample of large bore piping led to four E01 Files:
Finding (ER/A,ER/AB,ER/B):
1 Con 61ned with Findings:
2 Observation (ER/C,ER/D,PPR/DEV):
None Closed Item:
1 The ER/A41nding was issued because the RLCA verification analysis showed stresses exceeding the allowable for small attached vent and drain lines and the existence of two supports which were deadweight (4
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e 7-supports only (capable of resisting gravity but not two-way seismic motion).
A generic concern was also reported in ITR 17 in that in several cases, the design analysis did not apply the appropriate stress intensification factors in determining pipe stresses, particularly at socket welded connections.
4.3.1,.4.3 Verification of DCP Activities under the Corrective Action Program - Large Bore Piping and Supports A.
Large bore piping The IDVP reviewed a new sample of 18 DCP piping analyses chosen from the category of computer analyzed piping. This sample was chosen based on the definition of the verification of DCP activities in ITR's 8 and 35.
l The selected piping samples were chosen to include various combinations of concerns idqntified in the initial review phase, and to provide assurance that these concerns were incorporated and resolved in the DCP Corrective Action Program.
The IDVP performed its review by examining, through checklists, the DCP calculation packages and computer outputs. Model geometries for 12 of the analyses were field walked to ensure conformance between design drawings and as-built econfigurations. The checklists were used to verify that critical items concerning criteria, methodology,' and results were adequately checked and documented in the IDVP review process.' The IDVP review process included asse'ssments of the competeness, applicability and consistency of the DCP review and analyses.
In some cases, the IDVP performed alternate calculations to review the DCP calculations.
As a result of this review four new E01's were issued as follows:
EDI 1126 addresses the SIF discrepancy for intermediate butt welds and the omission of a SIF of 1.9 at valve / elbow interfaces. This item has been incorporated into the DCP final review checklist for review of potential impacts on all DCP analyses. E01's 1133, 1135, 1137 address discrepancies in valve modeling and weights. These E0I's have been combined to form a generic concern with valve modeling. This item has also been incorporated into the DCP final review checklist for review of 4
potential impacts on all DCP analyses.
The verification program conducted by the IDVP is not yet complete.
Based upon the efforts performed to June 25, 1983, the IDVP considers i
i the following aspects of the DCP work to be acceptable and to satisfy the licensing criteria:
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The DCP reanalysis of all original' work and the development of the DCP final review checklist is an appropriate program for qualification of all DCP analyses.
Qualification analyses in general reflect the as-built conditions.
Overall modeling methods were found acceptable, except for application of stress intensification factors (SIF) and valve-
-modeling as noted above.
Loadings.used in the DCP analyses were found acceptable. Loading data were found properly controlled and applied by the DCP.
Internal documentation was found to be in sufficient detail to allow the verification of transfer of data. Computer files and descriptions were indexed.
i Stress analyses were found acceptable for all reviewed analyses except two, which contained unique discrepancies and were reanalyzed by.the DCP.
Numerical accuracy of the calculations sampled was adequate.
In summary, the IDVP has concluded that DCP is following established procedures and licensing criteria, and is meeting the latest loading criteria and operating modes. The concerns on stress intensification factors and valve modeling were determined to be generic concerns.
These generic concerns are being resolved by the inclusion of specific checks in the DCP final review checklist. Certain valve models and SIFs will be reviewed by the IDVP after they have passed the DCP final review. None of the specific concerns that led to these two generic concerns caused an exceedance of the licensing criteria. The DCP Corrective Action Program for Design Class 1 large bore piping adequately covers all essential steps required to obtain proper i
qualification of the piping.
The IDVP considers the following aspects of the DCP work to be unresolved issues at this time: E0Is 1126, 1133, 1135, and 1137.
The IDVP intends to formulate a final conclusion as to the qualification l
of large bore piping and its conformance to licensing criteria when the IDVP verification is completed. The complete results of this verification will be reported in ITR 59.
I B.
Large Bore Piping Supports The IDVP verificatbn of the DCP Corrective Action Program for large bore pipe supports is defined in ITRs -8 and -35.
The IDVP review consisted of an examination of qualification of each pipe support for all seismic and non-seismic loads.
Seismic loads are the DE, DDE, and Hosgri events, while non-seismic loads are deadload, thermal accident, friction, fast valve closure, and relief valve opening thrust.
The IDVP has stated that all Design Class 1 large bore piping supports 1
were reviewed by the DCP to assure compliance with design criteria, as j
contained in the FSAR and Hosgr'1 report.
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_9 The IDVP selected a sample of the support design analyses to verify conformance to the DCP criteria and accuracy of calculation. The samples were selected on the basis of the following considerations:
supports associated with the large bore piping sample a review of the DCP General Pipe Support Status log to determine revision status. This log listed approximately 6000 to 7000 supports.
representation of various sup(port types,) pipe sizes, plant locations and organizations consultants perfonning design analyses.
i The IDVP selected a total of 22 support analyses for review. The support types were as follows:
5 snubbers i
6 spring hangers 6 anchors 7 rigid supports Design reviews of these analyses were performed to verify the following aspects of the design analysis:
i I
Validity and completeness of design inputs Compliance with design procedure and criteria Validity of design assumptions 2
Validity of analysis conclusions Approximately 70 percent of the support sample was field verified to confirm the as-built condition.
The IDVP perfonned an analysis package and pipe support review to evaluate the completeness of all pertinent design input data, output results, and associated documentation. Alternate calculations were performed where necessary, to assess the effects of various DCP j
assumptions and to confinn calculations.
Three EDIs were issued based on these reviews:
t E01 1122 was issued to note that the design analysis for one pipe support does not address support frequencies in the unrestrained direction as required by the DCP criteria. The DCP has revised this analysis to address frequencies in the unrestrained directions. This i
revision remains to be verified by the IDVP.
It is, however, not considered a generic concern since support frequency requirements were not included in the licensing criteria.
E0I 1129 notes that errors were made in calculating the weld stress for weld between pipe lug and supporting steel on a support. This item has been classified as an error Class C.
This E01 does not represent a
- generic concern.
E01 1131 notes that the design analysis for two supports do not evaluate 1
the shear lugs and attachment welds, as required in the DCP Corrective Action Program. The DCP has revised these analyses to include the shear i
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lugs and attachment welds. The IDVP review of the revised DCP calculations shows these stresses to be small. This EDI has been classified as a deviation.
The verification program conducted by the IDVP is not yet complete.
Based upon the efforts perfomed to June 25, 1983, the IDVP considers the following aspects of the DCP work to be acceptable and to satisfy the licensing. criteria.
~
Support drawings are satisfactory.
Loads and load combinations used in the pipe support analyses are i
correct.
j Pipe support frequencies are satisfactory (except as noted in E01 1122).
Pipe support stress analyses are satisfactory. (except as noted in EDI 1129).
j Attachments welded to the pipe are frequently not evaluated in the DCP analysis. Except as noted in the E0I 1131, they were found to be, satisfactory from IDVP calculations.
l Standard component supports such as' spring hangers, snubbers, and pipe clamps are satisfactory.
Pipe support analyses were generally perfomed in accordance with-the design procedures.
i The IDVP intends to formulate a final conclusion as to the qualification of and its conformance to licensing criteria when all analyses have been evaluated by the IDVP. This activity will be reported in ITR-60, i
4.3.1.4.4 Staff Review The staff of the Mechanical Engineering Branch and their consultant, the Brookhaven National Laboratory (BNL), reviewed the two ITR's, and attended a meeting with RLCA to obtain clarification on a numhr of i
topics addressed in this effort, and to resolve concerns raised in this review.
The following major concerns were noted and resolved:
1.
The comparison of support and nozzle loads calculated by RLCA and i
PGE show very large and significant differences. Furthemore, no comparison with allowable loads or stresses were presented. RLCA i
stated that the design and analysis of large bore supports would be reviewed separately as part of the IDVP verification effort of the DCP Corrective Action Program, and that this concern would be addressed during that review.
2.
The assumption of a heat exchanger as a rigid anchor even though its natural frequency was determined lower than the rigid anchor l
frequency criterion (20 Hz) RLCA indicated that this was done to determine sources of differences between RLCA and PGE calculations.
l Heat exchangers were verified separately.
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The staff evaluated the-analytical and modeling methodology used by RLCA in the verification analyses and concluded that correct and acceptable approaches had been used to determine various inconsistencies and errors in the PG&E designs and analysis of piping and equipment. They also stated that follow-up efforts on the initial verification will concentrate on verifying that PGE has correctly addressed the stated concerns.
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The IDVP has submitted a preliminary report on its verification of the l
DCP Corrective Action Program. This report indicates that the concerns r
raised in ITRs 12 and 17 are being addressed in this program. The final results of this verification will be reported in ITRs 59 and 60.
4.3.1.5 Brookhaven National Laboratory (BNL) Effort The BNL performed an independent verification of two PGE piping systems j
which are located in the annulus structure. The systems were chosen from the safety injection RCS (PGE problem 6-11) and from the component 1
4A-26)g water supply system to the reactor coolant pumps (PGE problem coolin l
The two systems were analyzed under the load combination which included Hosgri magnitude response spectra. The horizontal spectra were taken i
from the Blume responsc spectra while the vertical spectra were determined from the BNL evaluation of the modeling and seismic response of the annulus structure.
Two types of seismic analysis were performed, one using the envelope of i
the response spectra (unifonn support motion) and the other using the i
individual support response spect~ra (independent support motion). Other i
. loading applied to the systems consisted of pressure, dead weight and 1
differential seismic anchor movements.
I i
The results for the stresses indicate that for PGE problem 6-11 the calculated stresses are below the specified allowables except for one point where the stress is insignificant 1y above the allowable. For PGE problem 4A-26 all stresses are below the allowable.
For PGE problem 4A-26 all stresses are below the allowable. Support and allowable support loads were not evaluated.
l The results of this evaluation indicate that with appropriate response l
spectra this sample of piping systems satisfies the Hosgri stress l
criteria, even though these systems were originally designed to l
different response spectra.
Further details on the BNL effort is described in NUREG/CR 2834.
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4.3.1.6 Safety Evaluation The Staff has reviewed and evaluated the submittals by the DC Design Verification Program and the Independent Desrign Verification Program on
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1arge bore piping and supports.
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Based on the piping verification effort reported by the IDVP in ITRs 12 and 17, the DC Program has reevaluated and reanalyzed all Design Class 1 large bore piping and supports designed by PGE for Diablo Canyon Unit 1.
The results of this reevaluation resulted in a small number of piping changes, but a very substantial number of changes, additions and modifications of supports, i
The IDVP verification effort determined that in some of the sample analyses significant differences existed between the PGE and RLCA calculations for pipe stresses, support. loads and nozzle loads and valve accelerations. The primary causes for these differences appear to be inconsistencies between the design drawings and the as-built geometries, and incorrect specification of building spectra. These include incorrect valve orientations, missing valve supports, or differences in support location..Another cause for stress differences was attributed to incorrect use by PGE of stress intensification factors.
The results of the DCP reevaluation were summarized in tabular form which showed that all reviewed piping systems satisfied the corresponding stress allowables. However, as stated in Section 4.3.1.1 -
the table did not indicate a stress or load comparison for the supports.
We believe this to be a deficiency of the presentation.
Presumably since all upports were reviewed and qualified for satisfaction of licensing criteria this information must be available. We recommend that as part of the verification of the DCP Corrective Action Program, the IDVP verify and report that all supports of the reviewed piping satisfy the required allowable loads or stresses, as applicable. We consider this to be an open issue and will report its resolution in a supplement to this SSER.
The results of the reevaluation of piping required for fuel loading indicate that the loading combination which casued the highest stress ratios and support modifications was that which included thermal effects. We recommend that the IDVP perform an independent evaluation and verification of a sample of piping where this condition was significant, and that this be reported as part of the IDVP verification of the DCP Corrective Action Program. In view of the significant differences in support and nozzle loads reported in ITRs 12 and 17, we recommend that the IDVP repeat the calculations for these piping systems with the present support configuration and the current loading, and verify that the stresses and support satisfy all corresponding design criteria.
The IDVP has also reported the results of its verification of the Corrective Action Program for large bore piping and supports. Although this effort is as yet incomplete, our review indicates that the IDVP has performed an acceptable review, evaluation and verification of work performed by the DCP Corrective Action Program. They have concluded that, based on this review and the modification implemented by DC to satisfy the IDVP concerns, the DCNPP-1 large bore piping and supports satisfy the requirements of the licensing criteria.
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The completed verification by IDVP of the DCP Corrective Action Program
- on large bore piping and supports will be reported in ITRs 59 and 60.
The staff review of these ITRs will be reported in a supplement to this ;
SER.
We consider the extensive effort conducted by the DCP for qualification of the large bore piping, and the IDVP effort of review and verification of the DCP Corrective Action Program acceptable to satisfy the requirements for restoration of the low power license, Step 1, and to conduct criticality and low power testing, Step 2.
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g 4.3.2 Small Bore Piping and Supports 4.3.2.1.1 Small Bore piaji"9.
The DCF report stated that all Design Class 1 small bore piping was reviewed for compliance with the original design criteria. Small bore ~
t piping was defined by PGE as less than or equal to 2 in in diameter cominsi pipe size. This piping was designed mostly by the use of 3
i spacing criteria, and by dynamic analysis.
Two types of reviews were perfomed: a generic review and a sampling i
review.
l The generic approach was applied to those analyses or designs for which previous reviews indicated generic issues with a potential for physical modification to maintain compliance with licensing connitments. The following issues were included in this review:
p i
1.
Computer seismically analyzed piping and associated themal f
analysis.
2.
Valve qualification l
3.
Seismic and thennal piping anchor movement (SAM, TAM) 4 4
Design class change boundaries i
5.
Hot piping designed by spacing criteria
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The sampling approach was applied to those designs where modifications were not anticipated to maintain qualification, and to address design censiderations not included in the generic review. These design considerations included:
1.
As-built piping accuracy
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2.
Revised seismic spectra l
3.
Concentrated masses 4
Effects of pipe insulation weight 5.
Spans which exceed spacing criteria 6.
Anchor and equipment loads 7.
Equipment and building seismic and themal anchor movement i
l 8.
Themal analyses 9.
Integral valve bypass
- 10. Vents and drains r
For either review, the piping was qualified by span criteria or by j
l computer analysis.
I The span criteria used for qualification is described in Section 3.7 of l
l the FSAR and Section 8.0 of the Hosgri Report. This methodology was developed to assure compliance with stress criteria for non-analyzed piping and supports, and to provide data for qualification of associated r
equipment. These criteria were also revised to include the effect of i
insulation weight and spectra' revisions.
The methodology for computer analyses, including dynamic and static analyses was the same as that used for the design of large bore piping.
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Piping code stress equations and allowable stress criteria were also the same as those for large bore piping.
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Generic Review All piping for which dynamic saismic analysis was performed was revi6wed
.and qualified using the same methodology cutliried for 1Jtrge bore piping.
As built-walkdowns were performed and the 4ynamic analyses were reviewed to assure ccepliance with the. criteria. Thermal analyses associatsd with these seismic analyses were also reviewed.
Each active ' dive requir,ed to bring the plant to safe shutdown following a seismic event was checked to assure that the.acceleratic1s ir,duced by the pipirg syster satisfies vender allowable values.
In addition, inactive remotely operated vahes were also checked for acceleration.s.
Whers the valve is located within piping qualified by spar. tables, the l
valve was rigidly supported.
The boutidaries between safety-related and nonsafety-related piping were a
revitwed for all locations. The objective of t';is review was to assure
. protection of the safety-related side of the. code boundary.
Oual1fication of these boundaries was obtained by providing either an anchor (equipment, large pipe, pipe support anchcr) ser two restraints in - '
each lateral direction on the Design C10ss 2 cide and one in toe &yial i
direction on either the Class 1 or. Class 2 side.. The supports ca the Design Class 2 side weresqualified as Class I supports.
Piping designed by spacing criteria, with maximum operating thsperatures greater than tne spacing criteria method limitations, was identified and qualified to maximum operating teroperature conditions, Computer thenr31 analysis was applied when manual calculation was considered to bc inappropriate.
^
Sample Review The sampling review addressed 20 pipelines, and included a minimura of five cunfigurations or conditions for the issues of effect of pipe insulation. revised seismic spectra, concentrated masses, overspans, anchor and equipment loads, pipe as-built ccnfigurations, and building and equipment seismic and thermal anchor movement. Computer analysis was used to show oualification if necessary.
A randem sample of 13 (approximately 10%) computer themal analyses on small bore piping was reviewed to confinn that qualification by existing computer thermal anelyses is satisfactory. The sarre methodology as outlined for large bore piping was used.
Results of the paview and Reanalysis A suarary of the review of all piping previously seismically analyzed by coaputer, and oiping previously themally analyzed by computer with temperatures greater than 165'F or 200'F for carbon and stainless steel, respectively, was presented in tabular fom. All piping in this category was reanalyzed by computer analysis. The table of results also j
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4 include the results of the reviews of piping which were qualified using span criteria.
The suntdry shows that approximately 1550 pfping spans were analyzed.
Of these 84% were found to be acceptable as-built. One-and-one half (1
))% showed conditions of seismic overstress due to the removal of supports to cchieve the original thermal qualification.
Six-and-one-half (61)% showed an overstress condition due to a lack of flexibility jn accormodating thermal movements and equipmer.t SAM / TAM.
Eight (8)% showed conditions requirir.g support modifications resulting free the generic qualificaticn of code boundaries and valves. Certain c61culaticns were based on information which require confirmation and may car.se the calculaticns to be revised.
The review.of el) valves requirir.g seismic qualification has resulted in 19 support v;odifications. The generic review of piping affected by seismic and thermal anchcr movements of attached large bore piping was i
addressed by conducting worst case analyses. No piping modifications j
were found to be necessary; however, support modifications were required to facilitate themal 6re:ho. movements. All hot piping was analyzed by r
computer which ensures resciution of this is, sue on a generic basis. No t
. support modifications were required for SAM conside~ rations.
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Hping where Design Class 1/2 interfaces 6ccur was reanalyzed by corouter or span criteria. The r.wiew ir,41cated that no piping rc:fificatiens were required.
The results of the review cf all hot piping, i.e., normal operating teseratures of greater than 165'F for stainless steel and 200*F for carben steel, which was initially' designed by spacing criteria, indicate
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that Support ecdifications were required to obtain qualification of piping in this category. As a result, the sample approach was abandoned. All piping problems in thic category were reanalyzed. All piping in tne sample review was shown to be qualified as-built.
i However, three analysis consi.ierations addressed by the sample review were found by other reviews to require an expanaed review. The three i
areas are SAM / TAM, concentrated mass effects, and equipment qualificatien for piping loads. Eight vent lines off the feedwater and main steam lines adjacent to the steam generators were found to require i
modification due to the large seismic and thermal movements of the steam l
generators.
le addition, one pipe support on each RHR pump required I
modification due to the SAM and TAM of the pumps. Therefore, the equipmert SAM / TAM sample was expanded to include equipment where the poter.tial for hign seismig acd thermal displacements exists. Equipment l
such as the reactor coolant pumps, steam generators, pressurizer, and residual heat removal pumps were included in the review. All piping associated with such equipment was reviewed and qualified.
Design Class I piping attached to certain equipment, which was not I
originally specified as Design Class 1. was also found to exert loads t
a r
i 1
t
-4 beyond equipment capacity. This equipment was recently seismically qualified for the Hosgri event, but has not been reviewed under the CCP.
PG&E stated that all such equipment will be reviewed and qualified as appropriate.
4.3.2.1.2 Small Bore pioing Supports t
The DCP verification of Design Class I small bore pipe supports used the same approach as was us.ed for the verification of the small b6re piping described in 4.3.2.1.1 The generic review of these supports included a comprehensive r.sview of the following items:
1.
S.tandard support details 2.
Leads. from seismic and thermal piping ancncr movement 3.
Code boundary interfaces 4
Lug stress and ~1ocal lug effects on pipe stress.
s Sampling methods were used to assure qualification of supports where the items above did not require addressing, and to address design considerations not included in the generic review. The sampling procest was expected to confirm that these design considerations did not cause small bore support modificaticns.
If this was not the case, then further review was performed.
The sample review included the following:
1.
As-built pipir.g accuracy 2.
Revised spectra 3.
Concentrated masses 4.
Effect of pipe insulation weight S.
Spans exceeding spacing criteria 6.
Equipment and building anchor movemer.t 7.
Therral loads The locations of Design Class 1/ Design Class 2 (safety and non-safety) pipe interfaces, load combinations, and allowable stress criteria are the same as for large bore pipe supports. Small bore supports are also required to have a natural frequency of 20 Hz or greater in the restrained direction.
Methodology for Generic Review l
All standard support details were reviewed and recalculated as necessary to identify the maximum permissible 1 cad. Consideration of revised Hosgri spectra was included in this review.
If the supporting capability was reduced below acceptable limits, the affected supports were identified and corrected. Supports that provide the first restraint in each direction on a branch pipe attached to a larger 6
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diameter pipe were reviewed to assure compliacca with stress criteria e
including the effect of the large pipe seisr.ic and thermal ancho.
movement.
1 t.ikewise, those supports that serve to isolate Design Class 2 fror Clau F
1 piping were reviewed to assure qualification to Oesign Class I support desi5n criteria.
i Analyses.areimingperformed,basedonthemaximumallowablepiotscan i
for lug support configur6tions, to detennine a maximive acceleration i
allowable to raintain the pipe lug and local pipe within stress limits.
The results of these enalyses will identify areas of the plant where specific review of lug designs is necessary or it will demonstrate that lbgs are acceptable at all plar.t locaticns.
MethoSoloav for the Sample Review A sample review of the supports located on lines sub;jected to i
l temparatures of 360*F o greater was perfomed to demonstrate that isupports designed by span criteria for seismic loads cnly are conservative when compared to the actuel computer analyzed therma 7 plus seismic loads. Ten isometric drawings selected at random were used for
{
the sample.
The qualification of pipe supports for the cunulative effect of overspans pipe insulation weight, revised spectra, concentrated assses, pipe as-built configuration, and equipment and building ancher novement considerations is demonstrated by qualificatica to established acceptanr.3 criterit of all supports associated with the corresponding i
small bore pipe sample.
j Results of the Review and peana_1vsig s
The results of the geteric and saople reviews and res91 ting support modification are preser.ted in the section showing the small bore piping review results. A total of 1150 Ana11 bore supports have teen modified.
Gfthese,60%wererequiredtomeetrevisedDesignClass1DesignClass 4
2 interface criteria and 21% were required as a result of the large bore piping review. The remaining 19% tesulted from the generic and sample reviews. Specifically, revised specification of code boundaries resulted in 682 support modifications while revised seismic ar.4 thennal piping anchor movements resulted in 32 pin support modifications The generic reviews of piping previously computer analyzed, and hot piping, resulted in 121 support modifications. Detarmination of the load capacity of the standard small bore supports resulted in 49 support 1
i modifications.
3
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l The samp*q review of pipe supports previously designed by spin criteria, subjected to thermal loads indicates that all supports meet the revised l
span criteria. t.1kewise the sample review of randomly selected pipe supports indicated that no support modifications were necessary.
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4 The sample review to chek lug local stress has not been completed as yet. The current review ir. dica?. cts thct no suppo p modifications are necessary.
i 4~.3.2.2 Indeoendeq Desttyarig,catbn Proormn (IDi'P) Effort The IOVP rewiewed the adequacy ccd appitettien of the span rvles used i
for qualifying small Port. piping.
hits review was perferned by Robert L. Cloud and Associates (Rt.CA) aM reported in the Interim Technical Recert(ITRF30.
L i
Small bore pliaing is usually defit.c3 as piping less than or equal to two inches nominal diameter.
It has been gevral i.idatry practice to support piping of DMs } ire using instriktion files for placement of supports,-known as.' span rules", which are intanded to assure a 4
conservative design in lieu of maru detailed computer analysis.
4:
for Diablo Canyon Unit Il, span rule,s were also a@lf ed to Design Class 1 F ping in the renge of 2.6 tn 4 indes nombi pipa site (i1PS) in i
d.iameter. The Hosgri report al.to permitted qualification of 6 inch t
pipes by spo rule.$. TAerefore for purposes of review the. IDVP expandec the definittor, af 5vall bare piping to inclyh any Design C; ass 1 piping i
qualified cHy thru the use of span rules.
4 The DC Desfgn (ferification progrso defined small bore pipino as piping less than or apal to two indes @S $n diameter. TMrefMh, for the i
purpose of 101F verificaths of DCP corrective action re!.'sW to small bore piping and suppt,rts th's more rMtricted and custc. nary definition j
was.cdopted.
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4.3.2.2.1 Verifica?.ionJf an initial Pjqing Sarge, 7.4e ID;'P perforted se initial review of s Sanple cf small bore piping.
This review included 9e s election of the rimpM, generic verification
(-
of the span rules, tM fiefd verification of cpan rule implementation.
y
. The IDVP selected a s.emple of two set.s of piping for the in;tial review.
L he set wcs used to verify the sp,,n r/ilet gerorically and the second set l
wa3 used ta var.lfy the impleamntation c# the toan ruies.
l The wt used to verify the span rules steerir.c)1y was selected t
cons?dering the foliewinty paraseters/ ripe Sh p, asterial, i
Paramettrs were chosen temperetures, presswes, tad naturcl free!ueny@.timum design strgins and to mflect Loth these likely to caiacide AtS tt'ose ec.st ccamonly eaticyed throughoW. tM pict. This saeple l
consisted of fotr hypcGatical piping c nff. pre,0!cs s.
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Tne set, ned ta verify span rule inolementat4n Consisted of thret.
7ergths of pipirg, each obcut 150 feet in ler.ith. Complex pipie,q l
cer.figurttfons tunt were not specifically M$ressed !n the span rules i
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N (i.e., situations resolved by engineering judgement) were not included within this set. That portion of the review was deferred to the IDVP verification of DCP corrective action.
The IDVP generic verification of span rules, applied to the first set, considered the following load cases: pressure, deadweight, and Hosgri earthquake. Spectra were prepared and a stress analysis was perfonned for all load cases. The load cases were combined as specified in the Hosgri Report and the resulting stresses were compared *to the licensing criteria. The effect of welded attachments to the piping was also considered as part of this review.
The field verification of the second set addressed the following:
o Conformance of Plant "as-built" configurations to span rule requirements o
Documentation of support types and locations o
Reasonableness of IDVP analysis assumptions within the generic review of span rules described above as to lug details, insulation thickness, and other items.
The result of the verification of PGandE span rules is that the IDVP has determined that pipe stress for small bore piping supported with PGandE span rules meets the licensing criteria for Hosgri conditions.
The result of the field verification of span rule implementation was the conclusion that, for the sample, all piping was installed in'accordance with the span rules. Although pipe routing and support design configurations were observed that were not specifically permitted within the span rules, it is recognized 'that span rules cannot anticipate every possible configuration and that such rules must be implemented by engineers capable of exercising good engineering judgement. The IDVP deferred the review of specific instances where engineering judgement was necessary to the verification of DCP corrective action.
Ten Error or Open Item Reports (E0Is) were issued by the IDVP as a result of the initial review and were classified as follows:
Finding (CR/A;ER/AB;ER/B):
1098 Combined with Findings:
1058, 1059 Observations (ER/C;ER/D;PPR;DEV):
1043, 1045, 1046 Closed Items:
1024, 1044, 1047, 1048 Except for E01's, 1058 and 1059 all E0I's were issued to note differences between the field condition and design drawings. All these were closed as deviations when further review indicated the correct 4
quantities or dimensions were used in the design analyses. E01 1058 was 1
issued to note the possible exceedance of allowable stresses for certain lug stresses. E0I 1059 was issued to note three discrepancies: 1)the l
PG&E report shows certain pipe stresses above allowables, and some i
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i frequencies below 15 Hz, 2) the preliminary (1969) Blume report does not address span conservatism as implied in the Hosgri report, and 3) the span tables do not address insulation weight of 6 inch piping. This error was ultimately combined with E011098 as a class A/B error.
Although the span rules generally satisfied the licensing criteria, the 3
following generic concerns were noted:
The span' rules do not address insulated pipe.
o o
The span rules do not limit the areas where ses11 bore piping is installed and may not satisfy licensing criteria for hi,gh seismic response areas.
o The Hosgri report allows the design of 6 inch pipe by the span rules, but these rules do not address 6 inch pipe.
o The fundamental frequency for some span rule configurations are less than 16 Hz.
o For 3 and 4 inch pipe, the span rules do not limit the unsupported distance from a change of direction containing a axially restrained run of pipe.
o A demonstration of the conservatism of the span rule approach was not presented in the Blume Report, as implied in the Hosgri Report.
In addition, the use of engineering judgement, the verification of maximum vertical and horizontal spans and the field marking of hangers were items also noted.
These concerns were reported to DCP which comitted to address them as part of the DCP corrective action program. The IDVP has selected to verify that these concerns have been addressed and implemented thru the IDVP verification of the DCP corr'ective action program.
4.3.2.2.2 IDVP Verification of the DCP Corrective Action Program for Small Bore Piping and Supports The IDVP verification of DCP corrective action on small bore piping and supports is defined in ITRs 8 and 35.
a.
Small Bore Piping The IDVP verification effort consisted of examining the qualification of small bore piping for all seismic and nonseismic loads.
The IDVP performed design reviews for the DCP analyses selected. A design review checklist was developed for the IDVP review of computer analyzed piping to ensure that all necessary items were examined and documented in a standard format. These checklists cover all essential areas of review from modeling/ Coding accuracy of piping and valves, application of stress evaluation, to qualification of valve acceleration and nozzle loads.
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Also, the IDVP. performed a certain amount of field verification of the
.sagle computer analyzed piping to assess the adequacy for the piping walkdown isometric drawings that served as a basis for the computer
.model input.
The IDVP performed design reviews on the application of the span rules calculations. These span rules are listed in DCP Design Criteria Memorandum M40. The IDVP reviews of these calculations included the following items:
o Seismic spans and corresponding accelerations o
Thermal flexibility (SAM and TAM) o Code break requirements o
Support of eccentric masses (valves with operators) o Support loads o
Pipe stresses o
Use of engineering judgement In addition to the above types of reviews, the IDVP performed a more general review of the span rules. The areas of special interest and review included the following:
o Scope of applicability 1
o Frequency of seismic spans o
Thermal rules o
Spectral acceleration factors In all the above areas, alternate calculations were performed by the i
IDVP to assess the effects of various DCP assumptions and calculations where necessary.
~
The IDVP sample of DCP qualification analyses was selected to ensure conformance to criteria and accuracy of calculations. The sample selected was chosen to assess the essential steps of the qualification process. Specifically, groups of files chosen for review were as follows:
o Five samples out of a total of 81 computer analyses. The IDVP selections focused on a combination of the review issued with
' emphasis on piping in high seismic locitions and with high temperature operating modes.
o Four samples out of a total of 115 span rule calculation files In addition, the DCP span rules were reviewed by the IDVP for i
methodology and applicability.
No E01s have been issued to date concerning this review of small bore
- piping,
c The verification program intended to be conducted by the IDVP is not yet complete. Based upon the efforts performed to June 25, 1983, the IDVP considers the,following aspects of the DCP work to be acceptable:
Computer Analyzed Piping o
The computer analyzed piping reviewed by the IDVP adequately represented the worst cases for the issues / design considerations detemined by generic and sampling reviews.
o Piping walkdown isometric drawings reflected as-built conditions.
o Stress intensification factors were adequately input.
o Piping and valves were adequately modeled.
o Seismic analyses used appropriate spectra input.
o Themal operating conditions were input correctly.
o Piping and valves met stress and acceleration allowables.
o Numerical accuracy of the calculations sampled was adequate.
Applicationofspanrules(DCM-40)
Valves with eccent'ric operators were properly supported, when o
required (onee.ase).
o Temperatures and SAM / TAM dis' placements were properly determined.
o Seismic spans were in accordance with DCM M-40 or were qualified by additional DCP calculations, o
Sufficient piping overlap was considered for code break (between safety and non safety piping) requirements.
SpanRuleMethodology(DCM-40) o DCM-40 span rules may be applied anywhere in the plant as long as spectral acceleration factors are correctly selected and used.
Methodology is acceptable and the spectra reviews are continuing.
o Support spacing is established such that frequencies for uniform straight pipe spans are approximately 15 Hz. Rules and space reduction factors are provided to evaluate other spans.
b.
Small Bore Piping Supports A design review checklist was developed for the IDVP review of small bore piping supports to ensure,that all necessary items were examined 8
e.
b2 and documented. Checklist observations were further expanded with connents where clarification or more detailed consideration was appropriate.
In addition to the checklist, the IDVP design review included assessments of the completeness, applicability, and consistency l;
of the DCP review and reanalysis methodology.
The IDVP perfomed an analysis package and pipe support review to evaluate the completeness of all pertinent design input data, output-E results and associated documentation.
l Alternate calculations were perfomed by the IDVP, where necessary, to 4
assess the effects of various DCP assumptions and to confirm calculations.
j The IDVP selected a sample of 12 DCP small bore pipe support analyses to 1
ensure conformance to DCP criteria and accuracy of calculations. The selection process included the following:
o The DCP list of small bore supports that comprised the full DCP review sample (approximately 210 supports) was reviewed by the IDVP.
o Supports were selected to represent various support types, pipe sizes, plant locations, and organizations (consultants) perfoming design analyses.
o In general, the selected supports were associated with piping that was part of the IDVP small bore piping sample, o
Several supports were select'ed as a result of IDVP field verification activities for piping samples.
No E0!s have been issued as of this date.
l The IDVP verification program is not yet complete. Based upon the C
efforts performed to June 25, 1983, the IDVP considers the following i
aspects of the DCP work to be acceptable:
o The small bore pipe supports analyzed by the DCP adequately l
represent the worst cases for the issues / design considerations detemined by their generic and sampling reviews.
o Support drawings are satisfactory.
o Pipe support drawings and infomation used in the analyses reflect the as-built conditions.
o Loads and load combinations used in the pipe support analyses are 1
correct.
o Standard component supports such as spring hangers, snubbers, and pipe clamps are satisfactory.
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o Four analyses meet criteris.
4.3.2.3 Safety Evaluation The staff has reviewed and evaluated the'submittals by the DCP Design Verification Program and the Independent Design Verification Program (IDVP) on small bore piping and supports.
'~
The DCP has conducted an extensive review and has stated that this piping and its supports satisfy the criteria under which DC Unit I was initially licensed. This was determined thru an extensive reevaluation and verification of the piping designs and as-built configurations, which led to a considerable number of support modifications. The nature of these modifications was not described in the DCP report.
The OdP report is unclear as to the actual extent of the review. The scope of the review states that all Design Class 1 small bore piping was reviewed for compliance with the original design criteria. However there is no clear indicac.;.4 that the piping reviewed under the generic review and the piping reviewed under the sample review comprise the total small bore piping.
In addition, from the sense in which the report is written it appears that the evaluation has as yet not been completed.
The IDVP has reviewed the revised span rules and verified their implementation in design and construction. A number of concerns were identified which have apparently been resolved. This was reported in the IDVP verification of DCP corrective action program. However, the IDVP verification program has as yet not been completed. The IDVP has stated that a final conclusion on the qu'alification of small bore piping and supports and its conformance to licensing criteria will be reported when 8
all analyses have been evaluated by the IDVP. The IDVP has not indicated where the final conclusior.s will be reported. However, specific details on these analyses and the resolution of concerns are required for the Staff to reach a satisfactory conclusion on the qualification of the small bore piping and supports. The resolution of these concerns will be reported in a Supplement to this SER.
Until the Staff reviews and reports the final results of the IDVP verification of-the DCP corrective action program, the small bore piping and supports can be considered qualified for fuel loading, Step I, and initial criticality and low power testing, Step II.
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g 4.4 Equipment and Supports 4.4.1 Mechanical Equipment and Supports 4.4.1.1 Diablo Canyon Project The Diablo Canyon Project (DCP) has reviewed all Design Class 1 plant equipment listed in Mechanical Equipment and Component Section of Table 3.2-4 of the FSAR, and Tables 7-5, 7-5A, 7-6 of the Hosgri report, to identify equipment required for seismic qualification. Mechanical equipment includes valves, pumps, heat exchangerr. and tanks.
Qualification to DE, DDE, and Hosgri is required for all equipment except for the equipment of the gaseous radwaste system,- which is required to be qualified to DE only.
The specific load combinations and allowable stresses used for qualification of equipment are those listed in FSAR Section 3.9 and Hosgri report Tables 7.1 and 7.2.
The load combination for Hosgri seismi'c loading consists of dead load, pressure, operating loads and nozzle loads. The spectra used for checking seismic qualification were l
taken from Design Criteria Memoranda DCM-C-17, C-25 and C-30.
The 1
damping values which were used in the reanalysis were taken from Tabie 3.7 of the FSAR.
The DCP seismic qualification for all equipment was performed as follows:
(1) The spectra used for qualification were compared with the current controlled spectra, using appropriate damping values.
For Hosgri spectra, the. envelope of the Blume and Newmark horizontal spectral curves were used.
(2) Seismic spectra applicable for each component were systematically reviewed in a controlled fashion each time revised spectra were issued, to determine whether or not equipment seismic calculations needed to be revised. An evaluation and comparison was made with previous qualifying spectra, and reanalysis and modification were performed where necessary.
All of the equipment analyses were reviewed and updated or reanalyzed to assure equipment structural integrity and, if required, functional capability. The review. checked for correct seismic, gravitational, operating, and nozzle loadings. Where functional capability was required, clearances between rotating and static components were checked against deflections to assure that contact would not occur.
Field inspections were conducted to confirm a.s-built details.
The equipment was checked by one of the following methods.
If the minimum resonant frequency classifies the equipment as being in the flexible range, dynamic finite-element modeling was used. The computer programs used were ME210, BSAP and ICES STRUDL II, which are verified computer programs.
If the equipment is in the rigid range, the seismic loadings were static loads associated with the spectra zero-period accelerations. The finite element models were also used for the static loading cases where the
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% complex nature of the equipment necessitated a detailed model.
For simple equipment such as a fuel oil filter, a hand calculation was considered adequate.
The portable diesel fire pump was qualified by testing on a shake table.
The loading during testing exceeded the envelope of the Hosgri and DDE spectra. The containment hydrogen purge system supply and exhaust blowers were qualified by drop testing to "g" lev'els well above the appropriate " spectra curves.
Nozzle loads were factored into the analyses as they became available in the course of the Phase I piping program.
If the nozzle loads exceeded the allowable loads on the equipment, then either the calculated loads were reduced by more refined analytical techniques, or the piping system was modified to reduce the loads and/or the equipment was modified to accept the nozzle'lcads.
The'results of the DCP mechanical equipment review are listed in Table 2.3.1-1 of the DCP Report. Each analysis is stated to have demonstrated that the equipment is qualified to perform its safety function without modification, for the controlling spectra and load combination.
However, this Table also shows that the following equipment is not qualified for the nozzle loads:
1.
Boric acid tank 2.
CCW Heat exchanger 3.
Diesel generator 5.
Diesel transfer filter 6.
Waste gas compressor DCP anticipates that this equipment or support may be modified, or that the calculated loads will be reduced by further analysis.
In addition, t
field verification of some component configurations has as yet not been completed, such as ventilation system water supply and exhaust blowers and motors, ASW pump and motor and the containment fan cooler box.
Finally, since not all final spectra have been issued some of the calculations may have to be revised to assure that the affected equipment is qualified.
4.4.1.2 Independent Design Verification Program (IDVP) Effort The mechanical equipment and supports which the IDVP verified for seismic adequacy consisted of samples of tanks, valves, pumps and heat exchangers. The verification was performed for the IDVP by Robert L.
Cloud and Associates (RLCA).
[
For all equipment the IDVP performed an independent analysis of a sample of each item, a field verification of the selected equipment and a i
comparison of the installed configuration and dimensions against both the DC design drawings and design calculations. The IDVP used standard j
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.t dynamic analysis and stress analysis methods in performing their independent calculations. Both conventional hand calculations and 1
standard, bench-marked computer programs and solutions were employed in this effort. The verification analysis included an evaluation of not only the equipment itself, but the equipment support including anchorage. The Hosgri loading combinations and structural criteria used in the independent evaluation were taken from the Hosgri Report.
The results 6f the independent analyses and evaluations were compared to both the governing criteria and the design analysis results. The IDVP issued an ITR on each category of equipment describing the analysis-procedures and assumptions used, the *results and comparison of results, E01s, generic concerns, and conclusions.
Summaries of these are presented below.
The IDVP initial sample calculations did result in identification of certain deficiencies which warranted additional verification. The initial sample findings and recommended additional verification for each category of structures, systems and equipment are described in ITR-1.
For the mechanical equipment sample, additional verification was performed for pumps. The extent and results of the additional verification effort for this equipment is also discussed below.
In additicn to equipment specific. concerns, the IDVP identified generic concerns related to the control and use of the correct seismic spectra.
~
The.IDVP was verified that the DCP has addressed these Hosgri spectra.
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concerns in their corrective action program.
The IDVP also reported the verification of non-Hosgri aspects of mechanical equipment as defined by.ITR-35.
It stated that the DCP has reviewed all Design Class.I (or IE) mechanical equipment. The IDVP Phase II sample of mechanical equipment included a tank, heat exchanger, valve, fan, compressor, pump, and mechanical filter.
The verification emphasized differences from the Hosgri qualifications, particularly when the non-Hosgri qualifications are controlling. The following general technical areas were considered:
o Establishment of correct design criteria o Establishment of scope and responsibilities o Est'ablishment of correct design inputs (including defined loadings) o Reasonableness of assumptions o Applicability of analysis methods o Applicability of ccmputer programs o Consistency of results' based on reviewer judgement and/or simplified methods o Completeness of qualification o -Satisfaction of design criteria Overall analytical modeling techniques and methodology were evaluated on the basis of consistency with the as-built condition.
Selected details
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and dimensions in the qualification analyses were field verified on a sample basis to assure that required modifications were made.
4.4.1.2.1 Tanks The tank initial sample consisted of the boric acid, starting air receiver, and the diesel generator oil priming tanks. The verification effort included a field verification of physical dimensions, independent seismic and structural analyses, and a comparison of independent and design analysis results. This effort is reported in ITR-3.
For each tank RLCA performed th'e following:
o verified the tank's physical dimensions in the field o modeled the tank as a series of beams and lumped masses to determine the stiffness and the natural frequency o determined seismic acceleration using the natural frequency together with the applicable Hosgri response spectra o calculated forces and moments at key areas using the equivalent static method o computed stresses and loads at key areas such as nozzle attachments, anchor bolts, etc.
o compared the computed stresses and loads to allowable stresses and loads as designated by the licensing criteria For the boric acid tank, model based on the stiffness properties of the tank and skirt was used to derive the response of the tank-fluid system which was compared with the design analysis frequency results. The largest stresses at the anchor bolt and skirt were computed and compared to the allowable stress criteria. All the independently calculated loads and stresses were shown to be below the corresponding allowable values. Because of differences in analytical techniques, the design analysis results could not be directly compared with the independent analysis results. However, both approaches were considered to be applicable and the resulting stresses were found to be very low.
For the starting air receiver vertical tank the equivalent static method was used to calculate tank seismic forces and loads. A computer analysis was used to determine the local pressure discontinuity stresses at the support skirt to tank juncture.
The following key areas of the tank were evaluated:
o Base plate o Anchor bolt o Stand ring baseplate weld g
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o Tank wall o Stand ring to head juncture o Skirt The comparison of the computed stresses with the allowable stresses did not indicate any overstress or overload condition.
l Except for the different analytical techniques used, and conservative
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damping values considered in the design analysis, a comparison of the design and verification analysis revealed no gross differences in the i
results.
For the diesel generating oil priming tank, the frequency and the applicable seismic acceleration were determined using the stiffness values of the tank supporting structure and the attached level indicator. Loads and stresses on component parts were obtained by applying the acceleration values.
Stresses were computed at the following key areas and compared to the allowable. stress:
o Pipe and attachment weld at the base of the stand o Anchor bolts o Upper supports o level indicator In addition, the buckling load was calculated for the upper support.
The stresses independently computed were well below the allowable stresses (or loads).
I Different analytical techniques were used for the verification and design analysis of the oil priming tank and minor discrepancies in the design analysis were noted.
The stress values determined for the selected areas were much lower than those of the design analysis.
A discrepancy in the level indicator stresses was a result of RLCA's conservative calculations and the difference in the level indicator weight.
Seven E0I Files (one on boric ucid tank, two on starting air receiver tank, and four on oil priming tank) were issued and were resolved as follows:
Findings (ER/A,ER/AB,ER/B):
None Observations (ER/C, ER/D, PPR/DEV):
1011, 1017, 1030,.1053 Closed Items:
1012, 1015, 1054 Since no findings were issued, this initial sample of tanks constitutes the entire Hesgri sample on mechanical tanks.
Consequently, no additienal sarpling.or verification was required or performed.
4 D 4.4.1.2.2 Valves a
The following valves were identified as the initial sample:
o Auxiliary.Feedwater Valve (FCV-95) o'MainSteamIsolationValve(FCV-41)
Valve FCV-95 is motor operated and is physically located in the auxiliary bdilding. Valve FCV-41 is air operated and is located on the pipeway outside'of the containment building.
Results of the RLCA review of the initial valve sample were reported in ITR-37. The review methodology included independent calculations and field verification of design input quantities.
In addition, the IDVP performed field verification of physica1' modifications resulting from the initial sample review. Applications of loading combinations and structural design criteria were based on the Hosgri report. The stress limits are specified in the Hosgri report Table 7.1.
The IDVP effort consisted of the following-o The equipment physical dimensions and other design data were obtained from drawings and field measurements, o Analytical models were developed for frequency, stress, and deflection analysis.
o Seismic accelerations in combination with other loads were -
applied to the analytical models to calcu~ late the seismic response of the valves, o Calculated stresses were compared to the Hosgri structural criteria, and deflection clearances were evaluated.
o Results of the verification analysis were compared with the PGandE design analyses. Differences were evaluated for significance.
In general, RLCA used more rigorous and' detailed analytical techniques than PGandE used. This, combined with the diversity in conservatism of assumptions, loadings, and boundary conditions, in many cases accounted i
for differences in the results. in excess of the 15% criteria. 'In all cases, the calculated stresses were within the allowable values for both '
the verification analysis and the design analysis.
Five E0I files were issued and were resolved as follows:
l Finding (ER/A, ER/AB, ER/B):
None Observation (ER/C, ER/D, PPR/DEV):
950 Closed Items:
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The one observation, E0I File 950, was the result of a discrepancy in stiffener plate thickness determined from the field verification.
Although the IDVP did not' consider physical modifications of FCV-95 to be necessary to satisfy criteria, the DCP modified the valve by replacing a 3/8" thick plate with a plate of the i" design thickness.
The IDVP verified this modification.
No additiona.1 sampling or verification of valves was required.
4'.4.1.2.3 Pumps The following pumps were identified as the initial sample:
Turbine-Driven Auxiliary Feedwater Pump (TAFP) o o Auxiliary. Salt Water Pump (ASW)
'o ComponentCoolingWaterPump(CCW)
The AFW and CCW pumps are physically located in the auxiliary building.
The ASW pump is located in the intake structure.
Based on the initial sample verification results, additional verification was performed on the following pumps:
i o Fuel Oil Transfer Pump (FOT) o Motor-Driven Auxiliary Feedwater Pump (MAFW)
~~~
The results of the RLCA review of the initial pump sample were reported in ITR-32. The review methodology included independent calculations and field ' verification of design input quantities. Applications of loading combinations and structural design criteria were based on tne Hosgri report. Stress limits for pumps are specified in Table 7-1 for active pumps and in Table 7-2 for pump supports of the report.
~
The RLCA effort consisted of the following:
o The equipment physical dimensions and other design data were
. obtained from drawings and field measurements.
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o Analytical models were developed for frequency, stress and deflection analysis, The Hosgri response spectra'in combination with other loads were o
applied to the analytical models to calculate seismic response of the pump.
o Calculated stresses were compared to the Hosgri structural criteria and deflection clearances were evaluated.
o Results of the verification analysis were compared with the PGandE design analyses. Differences were evaluated for significance.
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than PGandE.
This, combined with the diversity in conservatism of assumptions, loadings and boundary conditiens in many cases accounted for differences in results in excess of the 15% criteria.
In all cases the calculated stresses were within the allowable values for both the verification analysis and the design analysis.
The IDVP issued the following six E0I Files:
Finding (ER/A, ER/AB. ER/B):
1022 Observations (ER/C, ER/D, PRR/ DEV):
1020, 1072, 1073, 1114 Closed Item:
1113 None of these files required action involving a physical modification.
E0I 1022 was issued in connection with' response spectra input to the ASW pump", and was redefined to track the DCP seismic reevaluation of the Intake Structure. E0Is 1073 and 1114 were also issued in connection with the ASW pump. The Error C classific~ation of 1073 originated from the improper application of dynamic response calculation methods.
E0I 1114 reflected failure to consider the pump as a partially submerged structure when evaluating-seismic response. These errors did not impact i
the acceptability of the specific pumps. However, they did result in required additional verification.
i This additional verification was performed for the sample previously identified. The _ specific objective of this verification was to address certain calculational deficiencies identified by E01s 1073 and 1114 The review of the additional Hosgri pump sample confirmed that the design analyses of these pumps did not contain these deficiencies.
4.4.1.2.4 Heat Exchangers The initial sample consisted of the component cooling water heat exchanger, the only heat exchanger analyzed by PGandE and/or its seismic
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service-related contractors for Hosgri qualification. The verification effort included a field verification of the support configuration, independent seismic and structural analyses, and a comparison of independent and design analysis results.
The independent analysis and review of the initial sample of heat exchangers is summarized in ITR-43. The RLCA effort consisted of the following:
o The heat exchanger's dimensions and support configurations in i
the field were verified.
o A model in considerable detail for the verification analysis was developed.
o An integrated analysis considering all combinations of loads to evaluate all key areas of the heat exchanger was performed.
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The IDVP listed a number of deficiencies of the design analysis procedures used by PGE. Major deficiencies were:
o The as-built support configuration was not used to generate i
seismic loads.
o Nozzle loads were not included in the evaluation of the entire support structure and shell.
o The effect of the additional load produced by the constraint of attached piping during heat exchanger seismic inertial movement
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was not considered in the evaluation.
Generally, the verification and design analyses used different approaches to analyze the heat exchanger. The verification analysis calculated shell stresses due to actual combined seismic, dead weight, pressure, and nozzle loads and compared these stresses to the allowables. The design analysis calculated shell stresses as a function of the seismic acceleration plus pressure and dead weight loads. These stresses were set equal to the allowables to determine the maximum seismic capability of the shell.
Because different approaches were used in the verification and design analyses, they yielded different results which could not.be directly compared. Both an& lyses, however, detennined that the heat exchanger shell stresses were below the allowables for Hosgri loading conditions.
Based on the verification results three E0I Files were established, and were classified as follows:
Finding (ER/A, E/AB, ER/B):
None Observations (ER/C, ER/D, PPR/DEV): 978, 1088, 1099 Closed Item:
None Since the component cooling water heat exchanger was the only heat exchanger in the IDVP scope required for Hosgri qualification and the verification results showed that all stresses were below the allowable values, no additional verification or sampling was considered necessary.
4.4.1.3 Staff Evaluation The staff reviewed the IDVP final report and the ITRs issued by RLCA on which it is based, on the topics listed in 4.4.1.3 thru 4.4.1.6.
Following is an evaluation on this effort.
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4,4.1.3.1 Tanks The technical data presented in ITR-3, Tanks, was not sufficient to~
I define either the tanks being considered nor the methods used in their
. verification. On the basis of the report alone a judgement could not be made of the adequacy of the verification effort. An audit was therefore perforwed by the staff of the work on which the ITR is based. The results of the audit indicated that in most cases the RLCA evaluations were more comprehensive than the PG&E design calculations, i.e., RLCA computed stresses at more locations or considered more design features than did PG&E in their original design calculations.
However, the tanks were originally designed to a version of Section VIII of the ASME Boiler and Pressure Vessel Code which prior to the Hosgri Report did not require as comprehensive an analysis as the one perfprued by RLCA. _ RLCA followed current engineering practice in performing this review.
The staff finds, after the ITR review and the audit, that the evaluation procedures and methodology used by RLCA to be acceptable. The evaluation, although based on simplified seismic models, hand calculations and limited computer analysis, are in general more comprehensive than the original design calculations. Additionally the calculations are supported by field verifications of the tank configuration and good quality control of the evaluation basis. We therefore find that the verification effort by the IDVP of the PG&E design analysis of tanks acceptable.
I 4.4.1.3.2 Valves The procedures described by RLCA in performing the independent analysis and verification of valves in ITR-37 are acceptable and would be expected to reveal any deficiencies in the PG&E design analysis reviewed. The information provided in the report is insufficient to allow any judgement of the correctness of the RLCA models or analysis results. However, audits of other RLCA analyses have indicated proper application of analytical and modeling principles.
4 This ITR addresses the verification of valve extended structures only.
THe Mosgri-report specifies loading combination and stress allowables for active valves and pumps and their supports in Tables 7-1 and 7-2.
For the nozzles, the extrene fiber stress in the piping at the
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nozzle-pipe interface is required to be smaller than the yield stress under the combined loading. For the valves in this report it is unknown if this condition is satisfied in the piping system of which they are a part.
After additional communication with RLCA, they indicated that this concern will be addressed and reported-in the verification of Diablo Canyon Corrective Action Program.
Subject to this commitment, we find i
the verification by the IDVP described in this ITR acceptable.'
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4.4.1.3.1 Tanks The technical data presented in ITR-3, Tanks, was not sufficient to define either the tanks being considered nor the methods used in their verification. On the basis of the report alone a judgement could not be made of the adequacy of the verification effort. An audit was therefore performed by the staff of the work on which the ITR is based. The results of the audit indicated that in most cases the RLCA evaluations were more comprehensive than the PG&E design calculations, i.e., RLCA computed stresses at more locations or considered more design features than did PG&E in their original design calculations.
However, the tanks were originally designed to a version of Section VIII of the ASME Boiler and Pressure Vessel Code which prior to the Hosgri Report did not require as comprehensive an analysis as the one performed by RLCA. RLCA followed current engineering practice in performing this review.
The staff finds, after the ITR review and the audit, that the evaluation procedures and methodology used by RLCA to be acceptable. The evaluation, although based on simplified seismic models, hand calculations and limited computer analysis, are in general more comprehensive than the original design calculations. Additionally the calculations are supported by field verifications of the tank configuration and good quality control of the evaluation basis. We therefore find that the verification effort by the IDVP of the PG&E design analysis of tanks acceptable.
4.4.1.3.2 Valves The procedures described by RLCA in performing the independent analysis and verification of valves in ITR-37 are acceptable and would be expected to reveal any deficiencies in the PG&E design analysis reviewed. The information provided in the report is insufficient to allow any judgement of the correctness of the RLCA models or analysis results. However, audits of other RLCA analyses have indicated proper application of analytical and modeling principles.
This ITR addresses the verification of valve extended structures only.
THe Hosgri report specifies loading combination and stress allowables for active valves and pumps and their supports in Tables 7-1 and 7-2.
i For the nozzles, the extreme fiber stress in the piping at the nozzle-pipe interface is required to be smaller than the yield stress under the combined loading.
For the valves in this report it is unknown if this condition is satisfied in the piping system of which they are a part.
After additional communication with RLCA, they indicated that this concern will be addressed and reported in the verification of Diablo Canyon Corrective Action Program. Subject to this commitment, we find the verification by the IDVP described in this ITR acceptable.
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4.4.1.3.3 Pumps Tne procedures followed by RLCA in performing the independent analysis and verification of pumps in ITR-32 are acceptable and did reveal deficiencies in the PG&E design analyses. For the most pr.rt, the models used by RLCA were designed to provide conservative results and were apparently as sophisticated as the models u. sed in the design analyses.
All reported stresses were found to be below the allowables and therefore the pumps evaluated appear to meet the licensing criteria.
However, for the auxiliary salt water pump, no results were presented for either the pump impeller shaft stresses and deflections, or impeller shaft bearing loads, if any.
In addition, no discharge head nozzle 4
l stresses were reported, nor compared to an allowable stress. However, in further communication with RLCA they stated that they performed a follow-up evaluat. ion of these items, and that the highest calculated
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stresses and loads were considerably below the allowable stresses. We therefore find the verification by the IDVP of the PGE design analysis of pumps described in this ITR acceptable.
4.4.1.3.4 Heat Exchangers The RLCA review and verification analysis of the component ' cooling water heat exchanger in ITR-43 seems both detailed and comprehensive. The models used appear to be more sophisticated and complete than the models used in the original design analyses. All reported stresses and loads were found to satisfy the allowables.
Certain items needed clarification on the basis and method of calculation. This clarification was provided by RLCA thru further communication, and found acceptable. The verification effort by the IDVP of the PGE design analysis of the CCW heat exchanger described in this ITR is therefore acceptable.
- 4.4.1.4 IDVP Verification of DCP Corrective Action Program Activities The IDVP verification of DCP work on mechanical equipment is defined by ITRs -8 anu -35.
The IDVP verification of the DCP work includes all aspects described in Section 4.4.2 of which the following were emphasized:
o Verification of the PGandE review methodology to assure that the correct spectra were checked by PGandE against qualification analyses.
o Completeness of qualification.
The IDVP performed a design review for the DCP reanalysis. A checklist was developed which covered all required criteria items, and critical analytical procedures, and ensured completeness of the IDVP review.
In addition to the checklist, the IDVP review included assessments of the completeness, applicability, consistency, and adequacy of the DCP review
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methodology was deemed not totally appropriate, alternate calculations were carried out by the IDVP to verify the conclusions of the D.CP reanalysis.
The DCP Corrective Action Program for equipment consisted of a review of the seismic qualification qualification, implemented by checking the i
latest seismic qualification data against those used for the i
qualification of equipment. This check used the latest response spectra for the DE, DDE, and Hosgri event. Whenever changes to the response spectra required requalification of the equipment, the equipment was requalified by analysis or testing.
4.4.1.4.1 Tanks The CCW surge tank was selected as the IDVP verification sample of the DCP imp 1'ementation. The CCW surge tank is a Design Class I tank and is located atop the auxiliary building at elevation 163 feet. This tank is classified and built to ASME Section VIII (Rules for Construction of Pressure Vessels). This is one of five mechanical tanks reviewed by the DCP. Of the five, three were verified for Hosgri loadings as part of the initial sample. Of the two remaining tanks, only the CCW surge tank was required to be evaluated for both DE and DDE loadings.
The IDVP issued E0I 1136 which notes that the DCP analysis for the CCW surge tank calculated bolt shear stress allowables that did not conform to established DCP criteria and the ASME code. However, the bolt stresses remain below the correct allowable values. The DCP analysis l
also did not consider internal pressure induced stress in the tank for
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the evaluation of tank stresses at-the nozzle. Tank stresses would exceed the specified allowable stress if pressure was considered using the same values and procedures as the DCP analysis. How3Y8r, it Was determined that the DCP reanalysis was very conservative and the actual pressure stresses were negligible. Thus, actual total stresses were below criteria.
The IDVP verification program for tanks is not yet complete. Based upon the efforts performed to June 25, 1983, the IDVP considers the following i
aspects of the DCP work to be acceptable and to satisfy the licensing l
criteria:
o The seismic spectra utilized by the DCP for tanks reflects 'the current spectra.
o The mathematical modeling used in the reanalysis was considered to be acceptable.
o All established DCP criteria are considered to have been adequately met.
The items identified in E0I 1136 are considered to be random analytical discrepancies.
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- The DCP Corrective Action Program for Valves is closely tied to the OCP efforts for piping. Certain valves were selected by the DCP for reanalysis to determine valve natural frequencies and allowable accelerations. These valves had been originally qualified by seismic service-related contractors to PGandE. Only motor-operated valves with eccentric masses were reanalyzed. The allowable acceleration results were then us'ed by piping to determine if modifications to the valve or pipe supporting structure were required.
An e.lectro-hydraulic valve was selected as the IDVP verification sample.
The valve is a Design Class I level control valve located on the pipeway structure outside the containment building.
It is one of the 6 different types of yalves analyzed as part of the DCP's ITP. This type of valve was selected for the IDVP review sample because a similar valve had caused an overstress condition in the pipe line in one of the IDVP initial sample piping analyses (Reference E0I 1069).
In addition, the actuator motor on these valves had been replaced.
Actual piping accelerations as well as any additional valve support 1
bracing were not included in this portion of the review because the results of this DCP reanalysis are to be used as criteria for the piping system qualification.
No E0I's have been issued in this review area to date.
The IDVP verification program for valves is not yet complete. Based upon the efforts performed to June 25,1983, the IDVP considers the following aspects of the DCP work to be acceptable and to satisfy the 4
licensing criteria.
. o The methods and results of the reanalysis comply with the established DCP criteria.
~~
o Mathematical modeling of the valve adequately represents the structure of the valve.
o Critical areas were examined.
4.4.1.4:3 Pumas Two identical fire pumps located in the Unit 1 Auxiliary Building at elevation 115 feet were selected as the IDVP verification sample. The fire pumps.are Design Class I equipment.
i This pump is one of eight pumps reviewed by the DCP. Of these eight, one was qualified by shake table testing and is thus excluded from the sampling of reviewed / reanalyzed pumps. Five of the remaining seven
._ pumps were included in the IDVP initial sample and additional verification work. Thus, with the IDVP review of the fire pump, six of I
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The IDVP verification program for pumps is not yet complete. Based upon the efforts performed to June 25, 1983, the IDVP considers the following aspects of the DCP work to be acceptable:
o Operability..as defined by rotating element clearances and interferences, was adequately demonstrated.
o The seismic spectra' utilized by the DCP for pumps reflects the-current spectra.
o The mathematical modeling used in the reanalysis was judged to be acceptable for the fire pump.
o With the exception of the item ider,tified in the next paragraph all established DCP criteria are judged to have been adequately met.
4 The IDVP has determined that the flanges en purps require reevaluation.
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This aspect of the DCP work ~fs therefore considered an unresolved concern at this time.
4.4.1.4.4 Heat Exchangers The CCW pump lube oil cooler 'was selected as the IDVP verification sample of the DCP's ITP activities for heat exchangers. One lube oil cooler is mounted with each of the three CCW pumps located in the
. auxiliary building at elevation 73 feet. The CCW pump lube oil coolers are Design Class I Equipment. This cooler, or heat exchanger, is one of two heat exchangers reviewed by the DCP. The other was the CCW heat exchanger, which was in the IDVP initial sample.
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One E0I file, 1130, was established which was resolved as a deviation.
The IDVP verification program for heat exchangers is not yet complete.
Based upon the efforts performed to June 25, 1983, the IDVP considers the following aspects of the DCP work to be acceptable:
o Seismic spectra utilized in the reanalysis were the current spectra.
o The methods and results of the reanalysis reviewed comply with the established DCP criteria.
i o Mathematical modeling adequately represented the cooler j
structure.
o Because all DCP reviewed heat exchangers are included in the IDVP, all such heat exchangers have been verified as complying with criteria.
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The IDVP verification program for heat exchangers is not yet complete.
Based upon the efforts performed to June 25, 1983, the IDVP considers the following aspects of the DCP work to be acceptable:
o Seismic spectra utilized in the. reanalysis were the current spectra.
o The. methods and results of the reanalysis reviewed comply with the established DCP criteria.
o Mathematical mcdeling adequately represented the cooler structure.
o Because all DCP reviewed heat exchangers are included in the IDVP, all.such heat exchangers have been verified as ccmplying with criteria.
The IDVP intends to' formulate a final conclusfon as to the qualification of a?1 mechanical equipment and its conformance to licensing criteria when all IDVP verification work in this' area is ccmplete. This will be reported in ITR-67. A review and evaluaticr. of this ITR will be reported in a supplement to this SSER.
4.4.1.5 Safety Evaluation The staff has reviewed and evaluated the submittals by the DCP Design Verification Program and the Independent Design Verification Program on mechanical equipment and supports.
The DCP has conducted an extensive review of the Design Class 1 mechanical equipment previously qualified to DE DDE, and Hosgri seismic loading. The review was perforned using currently accepted design methodology and the load combinations specified in the FSAR and the Hosgri report. Acceptance criteria for qualification were also those
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specified in the FSAR and the Hosgri report.
Equipment and supports were evaluated concurrently.
The DCP reported the results of their review in Table 2.3.1-1 of the DCP submittal. Each analysis was stated to have demonstrated that the equipment is qualified to perform its intended safety function.
However, the same table shows that in six equipment items the calculated nozzle loads exceeded the allowable' nozzle loads.
In addition, some component configurations have as yet not been verified nor all final spectra issued. DCP has indicated that some of this equipment or the supports may have to be reanalyzed or modified to accommodate the nozzle criteria or the final seismic spectra. We conclude that not all mechanical equipment is as yet seismically qualified to perform their f
intended safety function.
The IDVP perforred an extensive independent analyses of a sample of each major equipment category. They used standard and acceptable dynamic i
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analysis and stress analysis methods in performing their calculations on the equipment, equipment supports and anchorages.
Field verification of the selected equipment was also performed and compared with the
. installed configuration and DC desigr, drawings. Results of the calculations were compared to the design calculations and the design criteria listed in the Hosgri report, and published in a number of ITRs (3,37,32,43).
Based on their initial sample calculations the IDVP identified certain deficiencies which warranted additional verification, and generic concerns related to the control and use of correct seismic spectra.
The IDVP has also reported their verificaticn of DCP activities in the DCP Corrective Action Program. They are presently reviewing the DCP efforts to assure that the concerns stated by IDVP in their initial and l
subsequent independent verification are being addressed in the DCP Corrective Action Program. They have concluded that based on the current verification effort no major deficiencies in the DCP Corrective Action Program have been uncovered and that based on their independent evaluation of a sample of equipment, the equipment at DCNPP-1 appears to meet the established design criteria. This effort is, however, as yet inccmplete.
The completed verification effort by the IDVP of the DCP Corrective Action Program on mechanical equipment will be reported in ITR-67. The staff review of this ITR will be reported in a supplement to this SER.
We consider the effort conducted by the DCP for qualification of mechanical equipment, and the IDVP effort of review and verification of the DCP Corrective Action Program, acceptable to satisfy the requirements for restoration of the low power license, Step 1, and to conduct criticality and low power testing, Step 2.
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2.1 INTRODUCTION
s The HVAC system provides ventilation, heating and cooling to safety related systems. The HVAC. system must withstand the effects of the DE, DDE and Hosgri events and the systems are therefore designated seismic Class I.
The HVAC system is associated with the following systems..-
- 1. Forced draft shutter
- 2. Diesel-generator ccmpartment ductwork
- 3. Auxil'iary saltwater compartment ventilation
- 4. 4-ky switchgear ventilation
- 5. DC 480-volt switchgear ventilation J5. Auxiliary building-fuel handling building l
- 7. Control rocm ventilation and pressurization sy; tem.
The HVAC system is comprised of compressors, fans, dampers, filters, heaters, ductwork, registers' and duffusers, cortrollers, valves, po'sition indicators, motors, thermostats and control panels.
The primary sources of data used by the staff in its evaluation are listed below.
- 1. The IDVP Diablo Canyon Nuclear Power Plant-Unit-1---
Final Report.
-2. The Pacific Gas and Electric Company Phase I Final Report Design Verification Program.
~~
4.4.2.2 IDVP REVIEW The verification efforts of the IDVP consisted of reviewin.] two samples of the PG8E Diablo Canyon Project (DCP) verification of all the Design Class I HVAC equipment. These samples consisted of:
- 1. Supply fan S-1
- 2. Ccmpressor CP-35 4
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auxiliary building at elevation 154 feet 6 inches. The fan sample was selected en a random basis with a bias toward larger units. The compressors chosen were the only ones evaluated by the DCP.
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For both samples the IDVP performed a design review of the DCP reanalysis. This design review included assessments on the completeness, applicability, consistency and adequacy of the DCP review and reanalysis methods. Where descrepancies were noted, or methods deemed not totally appropriate, alternate IDVP calculations were made to verify the conclusions of the DCP reanalysis.
The verification program intended to be conducted by the IDVP is not yet complete as of June 25, 1983. However, the IDVP has issued two E0I's (1125 and 1127) as a result of the verification work done as of June 25, 1983.
E01 1125 dealt with use of incorrect spectra for vertical a'ccelerations for the compressor. The E0I was classified as error class C.
Later analyses using the corrected spectra showed no overstress condition prevailed, therefore, the E01 was closed.
E0I 1127 was issued due to two concerns over modeling techniques used in the evaluation of the fans. The concerns were resolved as being not significant based on the IDVP analysis. The item was therefore closed.
Based on the efforts performed as of June 25, 1983, the IDVP considers the following aspects of the DCP verification work to be acceptable and satisfies the licensing criteria.
- 1. The mathematical modeling of the structure was found to be adequate.
- 2. Applicaticn and satisfaction of established DCP criteria were found to be adequate.
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- 3. A concern did exist over the proper control and application of seismic spectra, an issuue which was related to work done in the initial sample.
The IDVP intends to formulate a final conclusion as to the qualification of the DCP verification program and conformance to licensing criteria when its review is complete.
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The DCP verification of the HVAC Equipment consisted of a review of the newest seismic qualification data against data used for the qualification of the equipment. The specific precadure used by the DCP was the following,
- 1. Compiled area drawings that documented safety-related HVAC equipment locations.
- 2. Listing all equipment within this area and documenting the inethod of qualification to applicable seismic spectra.
- 3. Reviewing the method'of qualification and qualifying any equipment that was nct qualified to seismic criteria.
- a. If spectra did not change for a particular location it was documented and no action taken.
- b. If the spectra affecting certain items were not identical to the previous qualifying spectra, a compariscn and evaluation were made.
However, if the spectra did not affect the seismic, qualification of the item, the reason was documented and a copy was placed in the system file.
- c. If the spectra affected the seismic qualification of a component, an analysis or test is performed and is issued. The documentation is updated.
- d. A redesign is performed and the equipment is modified, as required.
The DCP compiled a list of the equipment and components of the Class I HVAC systems. They were reviewed for seismic qualification in accordance with the current spectra defined in PG&E's DCM C-17 (Hosgri), -
C-25 (DE) and C-30 (DDE). They were also reviewed against the acceptance criteria for seismically qualifying these items.
Where the most current spectra exceeded the conditions under which the component was previously analyzed, a new analysis was initiated. The results of the analysis either confirmed qualification of the component or identified a physical modification. Where anaysis was not appropriate, equipment testing was used to demonstrate the designed performance under the qualifying seismic conditions.
9
HVAC Equipment 4.4.2.4 STAFF EVAlt% TION 4.4.2.4.1 IDVP REVIEW The IDVP review consisted of selectins tyr semples cut sf P6 fact a.c.c 4 compressors. The compesser was selected tim verification cated on concerns from the initial sample, The fan vs selected on a raMon basis with a bias toward physict.U y 3crger uM ts. The reviet of the IDVP to this point has steun that %e KVAC equ4mt was ettscetv modeled and the DCP criteria sppRsation was fen;nd to he sequ1%
Yhe IDVP review is not complete es yet ud the IDVP will provide. ttw fina?
conclusion on ITR no. 67. The ITR H scheduled to be rtbased ost farly 14, 1983, The staff will fully evaluate-the 10YF redev when K h completea and the final report is provb9d to the start.
4.4.2.4.:' OCP REVIEW The DCP review of the equipment consisted of U faeiea of tM otWS seis:nic qualification data a<3aint deta used fee the origim!
qualificatioc. This check wts performP.d using rat Uatsst rr tDo; spectra for the DE, DDE and Hngri we.nts. Ro chtnges to tw 7wseu spectra required requalification 4:f tLt Gepipaent.s 'shts vM dgM ty analysis er testing. The verf f hietien prtges af the It@ f 3 rya yet complete.
The Staff will corclet$ it's eva\\uxttM 4en Cht ID? w completed their verification.
l 4.4.2.5 CCNCLUSIDN The final report on the IDVP redM is not nadccM 0: Un t'o.4 n d m staff conclusions en the revias t pm sit E l
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4.4,2.1 ISTRe?)GION The elettferi rac3x4y support system contains appray,1mately 460 stendard detiqus v90 in the Glable Cibnyon Mant. There are more than 21,000 safety-class electrical racewty supp;rts in Unit 1, Each design has been gestica11y qualified te carcy a certain r: umber of cables / trays afn to be installp6 in particular areEr of tha plant. Tha support tocat$ons M based on tilovable spea criteils. The supports are i
constructed'oricarily M holted assetelies of cold-formed steel channel section atW 3 paced at 8 feet 6 inches or hss. They support cable tren and conMt on writs ed beneath f1cce clats in most of the WG&d aren throughoc the plant.
The Phase I review of the ac.W tr)O1 racemys tes ta ud upon a sample,of,20 raceway supports and the 9erification af DCP corractid acth was based an a second sample 9f N racessy stmpirt.<.
Class i instrui4nt igMfm 'l tubing cQntaiMng a fluid which runs W4% a transducer jo the system being mnnitored and a display device 3? 9 e p tte locat9en. The taking is small in diameter, typically 1/4 1cc pd cJnposed of steQilers ned or copper. The tubing supports are EcWIN dds of standRd cdd-forend femDers, WMed together or
?.senMeh With T.tacdard Mtaner devices. The insjority of Class I Ntructat t.:t$cg and suppce.A ust&tec with Class ! safetyerelated 1c3%wntation is Hjthin 9te co');tairiment structure. Tnere are also
$4Dhted ?ystems is teth tr.B Mxi?iary and tyrbine buildings. These 973toneer, seestng lin$ supdy preisurized fluid signals to the Class 1 30 m eentation.,
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TXt. pr?rry scatreat cY 4ta u*ed by the P.aff in its evaluatico are l
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7he fiVP Stibio Cp3kn t!:1 car Fmr Plant-Unit 1 Fnal Report.
2.
' t.$ Facific 6es ed Electric f.cmpany Phase I Final Report Design l
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3.
ICW fcertr) Technics *: Re % rt 7 " Electrical Raceway Supports" 4.4.3.2 iCYP PEVIEk I
4.4.3.2.1 Etf.CTRICAL RACf3AYS The IDVP review of the electrfgai faceeeys irIluded the following items for verification of the initial sampia.
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Evaluation of design criteria / methodology 2.
Determination of applicable Hosgri response spectra 3.
Sample selection 4.
Documentation of actual sample configuration at the plant.
The IDVP used a number of PG8E dccuments such as preliminary criteria memoranda, qualification analyses and drawings to evaluate the design criteria /methodol.ogy. The Hosgri report was reviewed for applicable response spectra at the sample raceway support locations. Following the response spectra review the IDVP selected a sample of 20 electrical raceway supports at various elevations and locations in each of the four safety related structures. The sample was selected on the basis of the jud@ ment of the IDVP as to which supports would have the least margin of safety.
Supports with long cantilever arms, relatively large supported mass, and long raceway. spans were typically selected.
Once this sample was selected the IDVP documented the as-built configuration by making physical measurements in the field.
The IDVP identified five concerns that relate to the design.
criteria / methodology and are listed below.
1.
Longitudinal support for conduits was not specifie.d in any' installation drawing and was not checked by PG&E in the qualification analysis.
2.
Raceway stresses calculated for the largest design span may exceed allowables.
3.
Joint fatigue and local joint flexibility may result in more flexiMe supports that are characterized by higher seismic response.
l l
4 Flexibility of adjacent supports may change the effective load distribution of the support being examined, resulting in higher seismic response of individual supports.
5.
The design methodology did not consider the coupling of support and raceway in determining natural frequency.
The following four additional concerns were raised as a result of 4
physical measurements taken at the plant.
1.
Sample 3 was installed with larger members than were specified in the original design drawings, i
2.
Sample 4 has an additional one inch conduit attached to the support which exceeded the specified maximum support capability.
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3.
Sample 15 was secured to a wall with a less conservative anchor bolt configuration than specified on the design drawings.
4.
Sample 20 was installed in an area not specifically authorized by the design drawing.
Seven E01's'were opened as a result of the. review (983, 1026, 910, 930, 1010,1093gnd1097). Two were classified as error Class A or A/B or 8 and three a re not classified.
EDI's 910, 930 and 1010 were combined with 983 fur tracking purposes. E0I 1026 was redesignated to cover the DCP turbine building review and E0I 1093 and 1097 relate to the auxiliary budding. The auxiliary building is evaluated in Section 4.2.4 of tnis SER.
The E0! 983 will be used to track the DCP activities in response to the ITR 7 recommendations that the OCP:
'1.
Modify design criteria and methodology used to seismically qualify electrical raceway supports.
2.
Define Hosgri response spectra inputs for all electrical raceway supports.
3.
Establish and implement a prcgram to ensure that raceway supports conform to design iristallation criteria.
4.4.3.2.2 IDVP VERIFICATION OF ELtCTRICAL RACEWAYS Th'e IDVP verification of the DCP corrective action plan is not complete as yet. The IDVP w'ill-provide a detailed description of the precess and results in ITR 64 which is' scheduled for release on July 22, 1983 as a draft for internal IDVP release and review. No date is scheduled for release for staff review.
The IDVP has provided some information in. the Final Report and this inform & tion was used by the staff t0 assess the status and direction of the IDVP efforts.
- The DCP corrective action program included a physical survey and l
documetitation of the location of each electrical raceway support, l
characterized by support type, generic qualificatikon of support types using worst-case seismic response spectra and alternative qualification of support types using worst-case "as-built" information for each individual support within such support category.
The scope of the IDVP review of the DCP corrective action program included the following categories of Class IE electrical raceway and i
raceway support anlayses:
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1.
Transverse and vertical support qualifications.
2.
Longitudinal support qualification.
3.
Conduit span qualification.
4 EDI resolutions For Category I and 2 the iDVP selected a sample of analyses as the basis for design reviews. Categories 3 and 4 were each centained in.a single calculation package and was reviewed completely by the IDVP. The IDVP review process includes review of the methodology and criteria, design review of the qualification analyses, and field verification of as-built configurations used as input to the analyses.
~
The IDVP verification of the transverse and vertical, and the longitudinal qualifications were accomplished through field verification of site conditions and design review of the qualification analyses. The design reviews were performed using technical checklists developed to reflect procedures and criteria documented in PG8E's design control manual DCM C-15, Revision 3.
For the conduit span calculations and E0I resolutions, the IDVP design reviewef the calculations using checklists developed specifically for each type of calculation and field verified a sample of'the as-built information used as input to the analyses.
The IDVP sample for the transvarse and vertical qualifications were chosen as representative of a variety of configurations, locations, leading conditions and analysis type. The IDVP selected 17 analyses from approximately 460 support types analyses.
The cable tray and conduit span qualification consisted of a review of the complete scope of the DCP analysis.
~
The longitudinal qualification consisted of a total of 5 samples of the cable tray and conduit analyses for runs in various locations, An additional sample will be taken to verify analyses performed by a consultant of the DCP.
The censultant's analyses were not complete when the IDVP made its preliminary sample. The DCP has performed a dynamic analyses for longitudinal motion and will be reviewed by the IDVP.
No EDI's have been issued as a result of the IDVP review of the DCP corrective acticn program es of the date of the Final Report.
The verification program intended to be conducted by the IDVP is not complete at this time. The results of the verification will be documented in ITR 64 Raceways and Supports scheduled for draft release internal to the IDCP of July 22, 1983. The staff has not had access to the documents. The IDVP considered the following aspects of the DCP work to be acceptable based on the IDYF efforts up to June 25, 1983.
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Field verification of a sample of the supports showed a satisfactory correlation with the drawings.
2.
Nine analyses followed procedures and were accurate within a satisfactory tolerance.
4.4.3.2.2 INSTRUMENT TU8ING AND SUPPORT The instrument tubing and support were not part of the initial IDVP Phase I program but were added later. The IDVP, therefore, did not define an initial sample nor make any review. The IDVP verification scope is verification of all Class I instrument tubing and tubing supports located in areas of the containment annulus structure which are 4
affected by the revised response spectra. The DCP program is based on 88 tubing supports.in' specific areas of the containment annulus structure and generic qualification of tubing spans on a plant wide basis, using worst case assumptions concerning Hosgri response spectra.
The methodology adopted by the IDVP for review of the DCP program included review of the completeness, applicability and consistency of the procedures and criteria implemented in the DCP design _ review of the six qualification analysis packages, and field verification of the input to the qualification analyses.
The IDVP review of the DCP plan implementation was based on-a 100 percent sample of the DCP program for instrument tubing and supports.
The DCP program implementation is contained in six qualification analysis packages which make up the IDVP scope for design review.
One of the six packages contains the generic tubing span qualifications.
The remaining five contain tubing support qualifications based on a DCP walkdown to identify controlling or specific worst case configurations in specific areas of the annulus structure,
~
The basic criterion utilized by the DCP to qualify instrument tubibg supports is to ensure that the supports are rigid. Rigidity is based on a minimum frequency of 33 Hertz. Those supports found not to be rigid I
were qualified by stress analyses utilizing criteria established fot pipe supports (DCM M-9). To qualify the' tubing, a worst case analysis was performed to show that, regardless of resonance, the tubing spans using the original support spacing do not experience stresses exceeding allowables.
EDI 1123 was issued due to the use of incorrect member' properties for a particular support type. The member properties were different from both the DCP documented as-built information'that which was confirmed by IDVP field verified. The E0I is unresolved as of the Final Report date.
The IDVP verification program is not yet complete. The results of the IDVP program will be reported in ITR 66. The scheduled release date for inhouse IDVP review is June 30, 1983. No date is scheduled for release to the staff.
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Based on the IDVP review as of June.25, 1983, the IDVP considers the following aspects of the DCP program to be acceptable.
1.
Four DCP qualification analyses have been verified to be sufficient and in conformance with licensing requirements.
2.
The DCP provided sufficient and accurate "as-built" survey document? tion supporting DCP qualification analyses for 12 support types.
4.4.3.3 QCP REVICW 4.4.3.3.1 ELECTRICAL RACEWAYS The DCP review of the electrical raceway consisted of assuring that the methods used previously in the DDE and Hosgri a.nalyses adequately represent the as-built conditions. This review included checking the weights of cables, trays, and conduits and the structural adequacy of the supports. The review indicated that come of the weights used in the original design were less than actual weight, therefore, tray and conduit supports were reanalyzed. The reanalysis of the electrical raceway supports also considered the effects of any structural response spectra. changes.
t The horizontal response acceler6 tion is taken as the greater of the two building responses due to either the east-west or the north-south ground motien ccmbined, by absolute sum, with the corresponding torstenal response. The damping value for cable tray systems and conduit systems used in these evaluations was 7%. The horizontal component of seismic load either transverse of longitudinal to the raceways that results in the highest stress en the member ynder consideration was combined, by absolute sum, with the stresses or forces due to dead load and vertical seis.mic load.
The specifications used to review the design of the steel members are the AISI " Specifications for Design of Cold-Formed Steel Structural 4
Members" and Part I of the AISC " Specifications for the Design, i
Fabrication, and Erection of Structural Steel for ' Buildings" appklicable l
to hot-rolled members. The allowable stress given in the AISC specifications was increased by 60%. The s)lcwable in AISI was i
l, increased, so that the margin of safety against yielding 1.0 or greatar with the allowance for local yielding at ccanections.
l Allowable leads on Unistrut bolts were taken as (90% of the zanufacturar's recomneeded citimate values. The alluwable leads on cocerete sxpansion anchors were taken as twice the working load permitted on PG4E Engineering Standard. The capacities in this standard represent 'a safety factor of 3.0 or above, based on test values pyblished by the Pittsburgh Testing l_
Laboratory and Phillips Drill Company, as wS11 as PG8E tests perforced at the plant site. The acceptanca limit on fillet welds on celd-formed steel me:rbers was 60; greater than the allowable given in 3ection 4.2.1 l
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Members". Unbraced ceiling mounted joints made of engle fitting were
,f' 5cing checked against rotation and low cycle fatigue.
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'6 In the transverse direction, the seismic loads used in the evaluation of the supports were based on the frequency of the cable tray < supports.
The mass considered acting at the support was the mass of the support itself and the tributary mass of the supported trays.
Each suppdrt was evaluated for the generic condition representing a worst case condition. This condition was determined by considering the variations in the location within the plant, ' sizes an,d numbers of raceway trays, signs of trays, support dimensions and bracing locations.
Any type of support that could not be qualified for its generic case 1
was investigated in'the plant to determine the worst as-built conditions usirig the field location of the support, dimensions of the support, bracing configuration, sizes and locations of raceways in the support, span lengths, and raceway identification numbers so that actual weights
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of raceways were determined. Using this information, static analyses were again performed for each support of that type in the same mannner as for the generic case, except that in this case as-built parameters were used, including the frequency of the as-built to determine the i
accelerations.
The cable trays were provided with longitudinal sesimic bracen The evaluation of these braces was similar to the transverse analyses.
i Design :::cdifications were prepared for supports that could not be qualified based on as-built conditions.
Field modifications were carrie;f out in the plant for the support.s affected.
The conduit supports were analyzed in the same manner as the cable tray supports for the transverse direction. The conduit supports do not have _
L the longitudinal bracing that wac provided in the cable tray system.
To quantify the longitudinal resistance of the electrical conduit system, a program was initiated to select and analyze those systems most susceptible to worst case longitudinal loading. All Class IE conduit runs were documented for their as-built conditions. Those runs that were vulneraole to longitudinal loading were identified and analyzed as systems.
Sixteen of the most heavily loaded and longitudinally flexible runs were selected for dynamic analyses. These represented the limiting cases that had little or no apparent longitudinal supports.
Finite-element models of the selected conduit runs wcre then developed.
Dynamic analyses of each of these runs werc parf:rmed to determine the response behavior and to calculate the loads resultiN from dioor responso spectra. These loads were then used to evaluated the safety factor associated with critical components of the supports, j
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A simplified but more conservative procedure was developed to evaluate the remaining runs identified for analyses. Those runs whose first mode of vibration in the longitudinal direction had a frequency less than 33Hz were stiffened by the addition of longitudinal braces to reach at least 33 Hz. The total sesimic load in any conduit run was calculated using equivalent static analysis and the zero period acceleration (ZPA) of the appropriate floor response spectra. This load was distributed among the supports proportionally to their longitudinal stiffness. The loads on each support were used to evaluate the safety factors associated with critical components of the supports.
If the results of the simplified analysis were too conservative, the conduit run was dynamically analyzed. Design modifications were'~ prepared for the supports that exceeded the acceptance criteria. Field modifications were carried out in the plant for supports affected.
The modifications required to date for raceway supports were limited to adding a simple bracing made of 1-3/4 in. X 1-3/4 in, angle iron, or additional welding around angle fittings, so that support members could develop additional moment capacity.
4.4.3.3.2 INSTRUMENT TUBING AND SUPPORT The review of safety-related instrumentation tubing and tubing supports consists of checking the rigidity of tubing and supports for the Hosgri event. A field walkdown was performed to determine the enveloping or supports that had the longest cantilevar or the heaviest loads and resulted in 88 support configurations. The natural frequency was determined and compared to 33nz, the criteria for rigidity.
If the support frequency was larger than 33Hz no further review was necessary.
If the structural frequency was less than 33Hz the supports were analyzed.
If the supports were found to be inadequate they were modified as necessary arid reviewed to determine the implication on supports outside the sample.
Two tubing supports were found to be inadequate. These supports were modified and reviewed for generic implications. A walkdown of the entire plant did not identify any other supports with the two deficiencies.
The original instrument tubing was supported to maintain a tubing frequency of at least 20 Hz. The tubing was evaltJated for this frequency and none were found to exceed allowable
- stresses.
4.4.3.4 STAFF EVALUATION 4.4.3.4.1 IDVP VERIFICATION The IDVP review of the raceway supports consisted of independent initial review of a sample of 20 raceway supports and verifying the DCP verification by reviewing an additional sample of 20 supports. The IDVP initial review discovered inadequacies in the construction and issued
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E01's, accordingly. The E01's have been combined to reduce the amount of items outstanding but the tracking of PG8E activities was maintained.
The activities of the IDVP are not complete and the results will e documented in ITR 64. The staff finds the IDVP efforts in the area of the electrical raceway, instrument tubing supports are adequate and should lead to an acceptable conclusion. The staff will review the results of the IDVP verification when the ITR 64 is issued and formulate its conclusion.
4.4.3.4.1 DCP REVIEW The DCP. review of the electrical raceway and instrument tubing and supports seems to be leading to a satisfactory conclusion and qualification.
~
The report, as filed, does not address the qualifications of the cable trays themselves nor how the flexibility of the cable trays interact with the supports. This subject should be addressed.
4.4.
3.5 CONCLUSION
The verification of the DCP' review has not been completed by the IDVP.
The staff cannot formulate a conclusion on the adequacy of the lectrical raceways and instrument tubing and supports until the IDVP has filed its
-final report.
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4.5 Other Seismic Design Verification Topics 4.5.1 Soils and Foundations 4.5.1.1 Introduction RFR performed guality assurance (QA) review of PG&E and their seismic service-related contractors which included the firm of Harding Lawson Associates Inc.,
(HLA). The QA review revealed that HLA did not implement a QA program for the DCNPP soils work performed for the Hosgri qualification analyses prior to June 1978. HLA's geotechnical work included:
intake structure, outdoor water storage tanks,_ buried diesel fuel oil tanks and connecting lines, and buried auxiliary saltwater piping. As a result of the QA review, RLCA and their consultant, Abendruh, Inc., formulated and carried out a review of HLA's soils work.
In this section the term RLCA represents the TES/RLCA team which carried out the geotechnical portion of the IDVP.
RLCA selected the following topics and samples of HLA's soils work for an independent design verification.
- 1. Outdoor Water Storage Tanks (0WST) lithology of rock bearing capacity
- 2. Intake Structure lithology and properties of backfill material bearing capacity lateral pressures sliding resistance RLCA reported their findings in a series of Interim Technical Reports (ITRs) and in a final report on the IDVP (Reference 10). ITR #16 presents results of RLCA's review of the OWST and ITRs #13, 39 and 40 present the results of RLCA's review i
of the Intake structure (Referenace 1, 3, 5, and 7 respectively). RLCA also 07/20/83 1
DIABLO CANYON SEC 4.5
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f5' evaluated the effect of lack of QA on HLA's soils work and independently veri-fied HLA's work for Hosgri qualification analyses.
This SSER is based on the documents referenced.
4.5.1.2 Outdoor Water Storace Tanks (0WST1 The OWSTs are situated on the east side of the auxiliary / fuel handling building
~
and are approximately 40 ft in diameter and 50 ft. high. These steel tanks were originally founded on a compacted fill placed over the bedrock.
Following the Hosgri evaluation in 1978, the compacted fill under these tanks was replaced with concrete and the steel tanks were encased in concrete. ITR #16 presents RLCA's review of HLA's geotech.11 cal work for the OWSTs and includes review of lithology of rock and allowable bearing capacity of the bedrock.
Reference 2 presents staff's evaluation of ITR #16.
4.5.1.2.~1 Lithology of the Rock The geotechnical investigations for the OWSTs performed by HLA in 1973 and 1978 'includedi. borings, laboratory tests on recovered samples and geophysical tests in the borings.
RLCA reviewed information in HLA's reports on the bed-rock depth (bedrock profile), description of the bedrock and strength proper-ties of the bedrock.
4.5.1.2.1.1 Verification of the Bedrock Depth i
RLCA verified the location of borings and the depth to bedrock by comparing information from HLA's field logs, HLA's reports and PG&E's drawings.
l' RLCA's verification revealed a discrepancy in the location of two borings. These were addressed in E0I 1101 and E0I 1100 reports and were classified as 'Devia-tions' (Class O error). The errors were as a result of. incorrect description of structures used as landmark-references in locating the borings.
The RLCA recti-fied this error and the location of the borings now shown in the HLA reports, l'
HLA field logs and PG&E drawings are consistent and correct.
07/20/83 2
DIABLO CAN)0N SEC 4.5 l
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4 The discrepancies in both the location of borings and depth to the bedrock are minor and within variations normally encountr. red in field explorations. The staff agrees with RLC-A's conclusion that HLA's determination of depth to the
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bedrock at OWSTs was' based on consistent set of data and is acceptable.
4.5.1.2.1.2 Verification of Bedrock Description and Strength Parameters RLCA compared the description of the bedrock in HLA's report, in HLA's field logs, and in reports by others on previous investigations (Blume studies 1968) 1969) at this site. RLCA concluded that the description of the bedrock as presented in the HLA's report was consistent with the description given in HLA's field logs and Blume reports.
-Ttte' bedrock is moderately weathered, hard, fine to medium grained sandstone and occasionalsilt$ tone.
HLA assigned strength parameters of 4 ksf for cohesion and 35* for angle of internal friction for the sandstone.- RLCA reviewed the results of two confined compression tests by HLA on samples of moderately to deeply weathered sandstone.
RLCA plotted one test data along with the HLA recommended strength parrmeters.
These two matched very well.
RLCA concluded that the HLA assigned strength parameters were therefore acceptable.
ITR #16 does not present the value of the modulus of elasticity used by HLA in their analysis.
RLCA calculated the modulus of elasticity for the bedrock using data from the geophysical survey performed in general vicinity of the OWSTs and assigned the lowest computed value 500 ksi to the bedrock.
RLCA concluded that the modulus of elasticity (500 ksi) was acceptable for the bedrock in the OWST
(
area.
Although the data base is minimal, the staff judges that the recommended strength parameters are reasonable and are within values generally quoted in the literature for Sandstone. The staff agrees with the RLCA's conclusion.
0 07/20/83 3
DIABLO CANYON SEC 4.5
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4.5.1.2.2 Bearina Capacity HLA recommended an allowable bearing pressure of 80 ksf for the OWSTs. RLCA independently evaluated the ultimate bearing capacity and concluded that the 80 ksf allowable bearing pressure recommended by HLA for the OWSTs foundation was acceptable.
The staff agrees with RLCA's conclusion.
HLA did not estimate the settlement of OWSTs. RLCA calculated the settlement to be 0.5 in for a maximum bearing pressure of 80 ksf and concluded that the com-puted maximum settlement was not detrimental to the structure.
The staff agrees with RLCA's conclusion.
Evaluation of dynamic loading conditions was not part of HLA's soils work and hence was not selected for review by RLCA.
4.5.1.3 Intake Structure The intake structure is a~ reinforced concrete building founded on a grout mudmat that was poured directly over the bedrock.
Three sides of the structure are backfilled to plant grade. The fourth side (west) of the structure has no back-fill and has openings to admit sea wat,er to the intake pumps.
Several years.
after (in 1978) the intake structure was constructed HLA drilled borings in.
the backfill material down to the top of bedrock and performed a geophysical t
survey in these borings to obtain data for the Hosgri evaluation of the DCNPP.
RLCA's review of HLA's work for the intake structure is reported in ITRs 13, 39, and 40.
ITR #13 (Reference 3) reports on lithology and properties of the backfill material.
ITR #39 (Reference 5) reports on the strength and bearing capacity of the rock and the lateral pressures on the walls of the intake structure.
ITR #40 (Reference 7) reports on the sliding resistance of the intake structure.
References 4, 6, and 8 present staff's evaluation of ITRs 13, 39, and 40 respectively.
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07/20/83 4
DIABLO CANYON SEC 4.5
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4.5.1.3.1 Lithology of the Backfill Material j
4.5.1.3.1.1 Determination of Depth to Bedrock RLCA verified the bedrock depth by comparing information from HLA's field logs HLA's reports and PG&E's drawings (1978 investigations).
The boring loca'tions shown i.n the above three sets of data matched reasonably well except for the location of hole no. 3.
The error, offset indicated as west rather than east, was attributed to a typing error on plate 1 of HLA's report.
E0I 1094 documented this error and classified it as Class D, Devia-tion er,ror.
This er.ror was corrected.
This comparison verified that the bed-rock depth.used in HLA's soils report and subsequent work is appropriate.
The staff agrees with RLCA's conclusion.
4.5.1.3.1.2 Properties of Backfill Material RLCA verified HLA's definition of backfill material properties as follows.
1.
RLCA independently calculated soil parameters using actual laboratory test data originally reported by HLA. The test results reported by HLA agreed with the values independently calculated by RLCA.
2.
For the backfill samples the soil classifications assigned by the geologist on the field logs were compared with the soil classifications assigned to the same samples by the soils laboratory technician.
The field classifica-J tion and laboratory classification were in general agreement. The classi-fication by the laboratory technician was again verified by RLCA on the basis of laboratory test results. This procedure verified the soil classi-fications given in HLA's soils report.
3.
The reported unconfined compressive strength and corresponding field blow count data for the test samples were compared with the strength and blow count values from published literature.
The comparison verified that the strength of the backfill material mentioned in HLA's soil report was of 07/20/83 5
DIABLO CANYON SEC 4.5
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.the same order of magnitude as that published in the literature for soils of comparable blowcount resistance.
Based on the above comparisons RLCA concluded that HLA's definition of the pro-perties of the backfill material is acceptable.
The staff agrees with RLCA on the soils data but finds the scope of verification lacking because it did not define the stratigraphy and numerical values of the properties of the backfill paterial.
RLC4 plans to revise ITR #13.
4.5.1.3.2 Bearina Capacity 4.5.2.3.2.1 Strenath of the Bedrock HLA inspected the foundation excavation for the intake structure in 1972 and their inspection memo describts the bedrock as moderately hard, moderately strong tuff and shale with minor weathering. All the borings at the intake structure were drilled only to the top of the bedrock.
In the absence of any. data on the bedrock at the intake structure, HLA used data from a 1968 investigation.
Two unconsolidated undrained shear strength (UU) tests were performed by HLA on samples of tuff recovered from borings drilled for*the intake line.
Both of these tests were conducted at the same confining pressure and yielded compar -
able results.
For the bedrock at the intake structure HLA assigned strength parameters ' f 3 ksf for cohesion and 30' for angle of internal friction.
o By comparing ft1 formation from HLA's field l'ogs, HLA's report and PG&E drawings for the 1968 study RLCA verified rock data such as:
location of borings, grade elevation, bedrock depth and description of rock samples.
The. data was con,-
sistent, except that the location of borings No. 18 through 22 were shown along the " Discharge line" in HLA report whereas they were actually along the " Intake line." To validate the HLA-assigned rock strength parameters for the intake struc-I ture,~RLCA compared them with the strength parameters recommended by HLA for the bedrock at the turbine building and at the OWST (c = 4 ksf, 0 = 35*, see Figure No. 4 in ITR #39).
RLCA compared the compressive strength measured (15 ksf) in tests with the compressive strength quoted (76 ksf) in the literature for tuff and stated that the strength values from HLA tests can be considered as a low-a I
07/20/83 6
DIABLO CANYON SEC 4.5
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Ap' bound value for the overall strength of the bedrock at the intake structure.
RLCA concluded that the HLA-assigned strength parameters are reasonab.le and acceptable for the bedrock at the intake structure.
Although the data base is minimal the staff is of the opinion that the assh>ned rock strength parameters at the intake structure are within the values generally quoted in the literature for similar rock and are reasonable and acceptable.
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4.5.1.3.2.2 Bearina Capacity and Settlement HLA recommended an allowable bearing capacity of 33 ksf for the bedrock.
RLCA computed the ultimate bearing capacity of the bedrock by assigning several sets of possible strength parameters for the bedrock and demonstrated the conservatism in HLA's recommendation.
They concluded that HLA's recommendation is conserva-tive and acceptable.
HLA did not estimate the settlement of the intake structure.
RLCA assigned a Young's modulus (500 ksi) and Poisson's ratio (0.39) for the bedrock, both obtained from the geophysical tests performed for the OWST.
RLCA estimated that a load of 33 ksf uniform bearing pressure would result in 0.75 in. of settlement.
Also, a differential load of 23 ksf will cause a 0.5 in. of differential settlement.
RLCA concluded that the HLA's recommendation of 33 ksf allowable bearing pressure for the bedrock under the intake structure is accept-able for rock strength and settlement considerations.
i l
During the technical audit meeting at RLCA's office (R.eference 11), the staff was informed by RLCA representatives that the maximum static bearing pressure under the intake structure is 10.16 ksf and,there is a local maximum bearing pressure l
of 26 ksf, under a pier.
Considering that the actual bearing pressures are low the staff concludes that bearing capacity and settlement are satisfactory for the intake structure. The staff also concurs with RLCA's conclusion on the bearing capacity recommendation by HLA.
4 D
07/20/83 7
DIABLO CANYON SEC.4.5 n v
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4.5.1.3.3 Lateral Pressures
~
The intake structure is backfilled along three sides and the fourth side (west side) is open to admit sea water to the intake pumps.
The bottom of the mat foundation is approximately 49 ft below the grade along the three backfilled sides and 7 ft below grade along the open side.
The soil backfill along three sides is approximately 36 ft high on top of the bedrock and the bottom of the foundation is embedded approximately 13 ft below the top of the bedrock. On the west side there is no soil backfill and the foundati'n is embedded 7 ft o
'below the top of bedrock.
For the backfill material, HLA assigned strength parameters of 35* for angle
~
of internal friction and zero for cohesion.
HLA calculated the lateral earth and water pressures on the east wall due to both static and dynamic (Ho,sgri SSE) loading conditons.
The structure is postulated.to slide westerly and hence lateral pressures'on the east wall of the. intake strcture were computed.
For the static loading condition, the lateral earth pressure was computed for the
~
at-rest earth condition. For the dynamic loading condition, the lateral earth pressure increment was computed for the dynamic active soil condition using a simplified method recommended by Seed-Whitman (Reference 9).
This computed ~~
dynamic active earth pressure was multiplied by 3 to compensate for the sim-plified assumptions in the analyses.
HLA also computed the lateral water j
pressure for both static and dynamic loading conditions. HLA combined water and earth lateral pressures for both static and dynamic loading conditions to obtain the total lateral force on the wall.
1
)
RLCA verified HLA's work by independently calculating the lateral pressures on the intake structure wall. For the backfill material, RLCA assigned strength parameters of 45' for angle of internal friction and zero for cohesion. For the static loading condition, the lateral earth pressure was computed for the active earth condition. For the dynamic loading condition, the lateral earth pressure increment was computed using Mononobe-Okabe method as modified by Seed-Whitman (Reference 9).
RLCA assumed the dynamic active earth pressure increment had a distribution with depth similar to that used for braced excavations in order to obtain the lateral earth pressure on a rigid wall.
RLCA also computed the i
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l 07/20/83 8
DIABLO CANYON SEC 4.5
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lateral water pressure for both static and dynamic loading conditions.
Water and earth lateral pressures for both static and dynamic loading conditions were combined to obtain the total lateral force on the wall. The total lateral force computed by RLCA was within 10 percent of the lateral force computed by HLA.
RLCA therefore concluded that HLA's determination of the lateral pressures on the wall is acceptable to IDVP.
RLCA's report (ITR #39) does not present a justification for the simplified assumptions in the analyses, the sensitivity of the estimated lateral forces to those assumptions, and the conservatism in the analyses.
In the absence of this information the staff considers this ITR to be incomplete. The staff con-ducted,a technical audit of the background materials referenced in ITR #39 (Reference 11).
Reference 6 presents staff's evaluation of ITR #39.
Section 3.3 of Reference 6 presents detailed comments by the staff on HLA's and RLCA's estimation of lateral pressures.
As a result of the above RLCA has agreed to revise ITR #39 to address the staff concerns.
The staff will review the re-vised ITR and report their findings in a future report.
4.5.1.1.3.
Sliding Resistance Figure 3 and 4 of ITR #40 show the foundation configuration for the intake structure.
The potential for westerly sliding of the intake structure was investigated by HLA.
The sliding surface and sliding resistance factors along this surface were postulated by HLA.
The resistance consists of the shear strength of the rock, the coefficient of friction between the concrete founda-tion and the rock, and the passive resistance of the rock at the western end of the structure. HLA used a shear strength value of 3 ksf for rock, ar; angle of friction of 30 degrees between the foundation and bedrock, and a passive resistanc'e of twice the rock shear strength.
RLCA verified the postulated sliding surface and resistance factors used by HLA, and RLCA concluded that HLA's recommendations were acceptable.
The shear strength parameters used in the analysis are based on limited data, but the staff believes that they are reasonable and agrees with their use.
- RLCA, however did not evaluate the total lateral force, total resistance to sliding I
1 07/20/83 9
DIABLO CANYON SEC 4.5 1
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and the resulting of the factor of safety against sliding.
This information is vital in assessing the margin of safety against sliding and for this reason the staff considers ITR #40 to be incomplete.
Reference 8 presents the staff's evaluation of ITR #40.
RLCA has agreed to revise ITR #40 to address the above concerns.
The staff will review the revised ITR and report their findings in a future report.
~
4.5.1.4 Conclusions The NRC staff has reviewed the IDVP Final Report and ITRs #13, 16, 39 and 40 prepared by RLCA for IDVP of the DCNPP and conclude the following.
HLA did not enforce a QA program in their Hosgri qualification work for the DCNPP prior to June 1978. QA review by RFR resulted in E0Is of Class D, Deviation errors which have been rectified.
These errors do _
not have any significant bearing on the design and/or safety of the structures.
The geotechnical data available for the 0WST and intake structure is minimal. The design strength parameters were assigned by HLA based on available test data and engineering judgment.
Both RLCA, and the NRC Staff concurs with the HLA on the reasonableness of the assigned strength parameters.
The staff agrees with RLCA's conclusion that HLA's work for the static loading condition of the Outdoor Water Storage Tanks is acceptable.
RLCA is revising ITR's 13, 39 and 40, for the intake structure.
The l
staff will perform evaluation of the revised reports when they become available.
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07/20/83 10 DIABLO CANYON SEC 4.5
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References 1.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils-Outdoor Water Storage Tanks, Revision 0, ITR #16, by Robert L. Cloud Associates, Inc., December 8, 1982.
i 2.
Report Evaluation by NRC Staff
" Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils-Outdoor Water Storage Tanks, Revision 0, ITR #16, by Robert L. Cloud Associates, Inc..
December 8, 1982," May 27, 1983.
3.
' Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verifi-cation Program, Soils - Intake Structure, Revision 0,~ ITR #13, by Robert L.
Cloud Associates Inc., November 5, 1982.
4.
Report Evaluation by NRC Staff
" Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils - Intake Structure, Revision 0, ITR #13, by Robert L. Cloud Associates, Inc., November 5, 1982,"
May 23, 1983.
5.
Interim Technical Report, Diablo Canyon, Unit 1, Independent Design Veri-l fication Program, Soils-Intake Structure Bearing Capacity and Lateral Earth Pressure, Revision 0, ITR #39 by Robert L. Cloud Associates, Inc.,
February 25, 1983.
6.
Report Evaluation by NRC Staff
" Interim Technical Report, Diablo Canyon,
[
Unit 1, Independent Design Verification Program, Soils-Intake Structure i
Bearing Capacity and Lateral Earth Pressure, Revision 0, ITR #39, by Robert L. Cloud Associates, Inc., February 25, 1983," July 13, 1983.
t 7.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Design Verification Program, Soils Report - Intake Struture Sliding Resistance, ITR #40, Revision 0, by Robert L. Cloud Associates Inc., March 9, 1983.
i 8
07/20/83 11 DIABLO CANYON SEC 4.5
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A,s 8.
Report Evaluation by NRC Staff
" Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils Report - Intake Structure Sliding Resistance, ITR #40, Revision 0, by Robert L. Cloud Associates, Inc., March 9, 1983," July 7, 1983.
9.
Seed, H. B. and Whitman, R. V., " Design of Earth Retaining Structures for Dynamic Loads," ASCE Speciality Conference on Lateral Stresses and Earth RetainingIStructures,1970.
l 4
10.
Final Report - Independent Design Verification Program, Diablo Canyon Nuclear Power Plant Unit 1, by Teledyne Engineering Services, May 31, 1963.
11.
Memo from B. Jagannath, GES/SGEB, to G. Lear, SGEB,
Subject:
" Audit of Geotechnical Aspects of Diablo Canyon, Unit 1, Independent Design Verification Program - June 8-10, 1983,"- dated July 11, 1983.
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07/20/83 12 DIABLO CANYON SEC 4.5
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4.5.2 Shake Table Testing 4.5.2.1 Introduction PG&E employed testing for certain Class IE electrical equipment and instrumen-tation subject to this design verification.
For Hosgri qualification, the cri-teria used are in conformance with IEEE 344-1975, Recommended Practice for Seismic Qualification of Class IE Equipment for Nuclear Power Generating Sta-,,
-tior.s and Regulatory Guide 1.100, Seismic Qualification of Electrical Equipment for Nuclear Power Plants, August 1977.
To obtain a representative sample for design verification, RLCA reviewed the list of Class IE el'ectrical equipment and instrumentation qualified by shake table testing.
Seven groups of items, tested at Wyle Labs, were chosen as the i
sample according to equivalent physical locations to facilitate definition of the required test.
RLCA reviewed the initial sample in two segments.
The first and major segment was the verification of Wyle grouping and seismic
'~
inputs for Class IE electrical equipment, which were reported in ITR-4.
The second segment was the design verification of shake table test mountings used in testing Class IE electrical equipment.
This verification was reported in ITR-44.
Detailed staff review of ITR-4 and ITR-44 are also contained in Appendix 4.5A and Appendix 4.5B respectively.
4.5.2.2 Verification of Initial Sample:
Grouping and Seismic Inputs The RLCA review of the Wyle grouping and testing sequence is summarized as follows:
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07/20/83 2
DIABLO CANYON SSER 1 d
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'sN (1) Reviewed the test procedure Wyle used to test each of the seven groups of Class IE electrical equipment and instrumentation.
(2) Verified the location of the electrical equipment and instrumentation included in the seven groups.
(3) Developed " worst case" response spectra for each group.
These spectra l
provided'the highest seismic accelerations associated with the location of the group.
(4) Made two response spectra comparisons.
The RLCA worst case response spectra (worst case spectra) was compared to the Wyle test response spectra (test spectra).
The Wyle target response spectra (target spectra) was compared to the test spectra.
The RLCA worst case spectra were generated for two time histories (Blume and Newmark) according to building, floor location, elevation, type, and damping.
The types of spectra were both vertical and horizontal.
The horizontal spectra consisted of effects of East-West translation, North-South translation, East-West torsion, and North-South torsion.
The RLCA worst case horizontal response spectra were developed by' adding torsional effects to the transla-tional spectra.
The test response spectra must envelop the required response spectra by at least 10%.
Both the RLCA worst case spectra and Wyle target specta were developed to represent the required response spectra.
I Four E01 reports, 1005, 1007, 1011, and 1049 were issued by RLCA as a result i
6 i
of design verification.
E0I's 1005, 1007 and 1049 were later closed and E0I
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1013 was resolved as a Class B Error.
The E0I 1013 was subsequently downgraded j
and the. equipment was demonstrated to be qualified.
The resolution of these E0I's were found to be acceptable by the staff.
The staff also concurred RLCA's recommendation in that the correctness of target response spectra specified for all items shake table tested by PG&E e
07/20/83 3
DIABLO CANYON SSER 1 E
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and seismic serv 1ce-related contractors be subjected to additional verification.
RLCA recommended the following four specific actions.
(1) Confirm field locations of all equipment (2) Select the applicable Hosgri response spectra (3) Develop the worst case response spectra (4) Compare the worst case response spectra to the target response spectra specified in the testing procedures.
4.5.223 Verification of Initial Sample of Shake Table Test Mountings For shake table testing, the test mountings were intended to simulate the in-service condition.
For testing convenience, some equipment was mounted to the shake table through an interposing fixture which was intended to simulate the dynamic and structural characteristics of the in-service mounting.
Test procedures and test reports were examined to determine the mounting configura-tions and fixtures'(if any) used for the test of each item of equipment. Where the test mountings were identical to the inservice mountings, they were judged to meet criteria.
l For equipment with test mountings not identical to in-service configurations2 each test mounting was evaluated to determine if it adequately represented the dynamic and structural behavior of the in-service configuration.
Of the 31 electrical equipment items tested, 25 were found to meet criteria.
One was classified as an error, and one was excluded from review as being non-Class IE.
The remaining four items (mountings of the main annunciator typewriter, battery charger cabinet, and the snap-lock limit switch) were not reviewed because they have been ratested or replaced by the DCP and should therefore be reviewed as part of DCP activities.
07/20/83 4
DIABLO CANYON SSER 1
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.I Two E01 reports were issued by RLCA:
E0I 1119 was classified as a Class C j
Error because the documentation of the test mounting configuration was not 1
sufficient to allow an evaluation of the structural adequacy of the in-service mountings.
This mounting was then qualified by DCP analysis, which was verified by the IDVP.
E0I 1118 was classified as a Deviation.
The staff concurs with the above IDVP verification.
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4.5.2.4 Veriftcation of DCP Activities i
The IDVP verification of DCP work on shake table testing is documented in ITRs-8 and -35 and in response to IDVP concerns developed during verification for the initial sample.
The results of'the verification will be reported in ITR-67.
The staff evaluation will be made when ITR-57 is issued.
The DCP Internal Technical Program (ITP) of seismic qualification is conducted by checking the latest response spectra for the DE, DDE, and Hosgri event against data used for equipment qualification.
Whenever changes to the response spectra required requalification of the equipment, the equipment was requalified by analysis or testing.
Equipment identified for review comprised that asso-ciated with the engineering safety systems designed by PG&E (reference) PG&E Phase I Final Report, Section 2.3).
DCP reviewed the validity of the previous seismic qualifications of equipment against current spectra.
If the qualifying test response spectra did not completely envelop the current required response spectra, an attempt was made to qualify the equipment by analysis.
Otherwise, equipment nodifications would be performed.and the equipment would be retested.
f The sample selected by the IDVP for verification of the DCP's ITP for shake f
table tested equipment consists of the portable fire pump and radiation mor:itor RE-14A, both are Design Class I equipment.
i f
The portable fire pump represents the only shake cable tasted mechanical equip-i
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ment.
Radiation monitor RE-14A, on the other hahd, represents one of approxi-i mately 27 catggories of tested equipment within the electrical equipment and l
9 I
07/20/83 5
DIABLO CANYON SSER 1
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's s'i instrumentation scope.
For both sample items, the IDVP performed design reviews and tes't reviews of the qualification documentation.
No E0Is have been issued to date for this review area.
The verification progre.m intended to be conducted by the IDVP is not yet complete. The sthff agrees with the IDVP's conclusion that, based upon the ef forts -perfor~ ed tc June 25, 1983, the following aspects of the DCP work'are m
acceptable and satisfy the licensing criteria.
(1) Applicable criteria have been identified and applied for shake table testing.
(2) Functional capability requirements have been specified and met.
(3) Mounting of the ' test specimens were either representative of the installed condition or were adequately evaluated.
4.5.2.5 Conclusion Based on the staff review of the design verification performed to date by PG&E and IDVP, it is concluded that for the sample of equipment items and their countings selected, the seismic qualification using shake table testing is ade-quately performed and therefore acceptable.
The staff agrees with the IDVP
~
findings and ccncurs in the recomme.ndations as stated in Section 4.5.2.2 for i
additi6nci verification for correctness of target respcnse spectra specified for all items shake table tested by FG&E and seismic service-related contractors.
The final staff conclusion on the overall adequacy of the shake table testing will be made when the IDVP verification of DCP work in this area is completed.
4.5.3 Seismic Qualification Interface - Westinghouse Main Control Board (MCB) 4.5.3.1 Introduction The Diablo Canyon Unit 1 MCB was procured for FG&E by Westinghouse (W) in accordance with an equipment specification issued in 1971.
W specification 07/20/83 6
DIABLO CANYON SSER 1 w-4
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s required that the MCB should be qualified to Ig horizontal and 0.5g vertical with stresses within allowable limits, and for 2g horizontal and lg vertical stresses should not exceed the yield point. MCB was supplied by Reliance, and Reliance used a private consultant to qualify the MCB by analysis.
This is the original analysis which predicted the lowest natural frequency of the MCB to be above 70 Hz based on a simple analytical model used.
Stresses were analyzed and s,hown to be well within allowabi'e range.
The axial load in one of the bracing members slightly exceeded the allowable load, and the report recommended Addition of two bracing members to each end frame.
The next phase of reevaluation was caused by the need to evaluate the adequacy of the MCB to the Hosgri earthquake in 1977.
The revised seismic input at the base of the MCB produced 1.55g norizontal and 0.81g vertical; this is the original Hosgri input. These values are lower than the original qualification level of 2g horizontal and lg vertical; thus the MCB was acceptable under 1977 Hosgri evaluation.
The final phase of the MCB qualification developed when the independent design verification program generated new floor response spectra for the auxiliary building.
These new floor response spectra, referred to as current Hosgri spectra, indicate higher values of zero period acceleration (IPA) for the ver-t[caldirection1A5gasopposedtothequalificationlevelZPAof1.0g.
It
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was during this final evaluation process that the MCB was modeled using field measurements and results of in-situ tests.
In-situ tests pointed out the existence of natural frequencies between 15 to 28 Hz, much below 71 Hz - the, value of the lowest natural frequency calculated in the original qualification report.
Because of the severity of the current Hosgri spectra at the base of the MCB in the 15 to 33 Hz range, W has chosen to retest selected devices that are attached to the MCB. W has also proposed modification of the MCB.
4.5.3.2 Evaluation The original analysis modeled the MCB as a uniform cantilever beam restrained at the base by the floor.
It appears that the MCB behaves as a horizontal beam supported by rigid cantilever frames; and this type of behavior yielded the lower natural frequencies.
The mcdification proposed is to add plates and channels on top of the MCB in order to strengthen the beam property of the MCS 07/20/83 7
DIABLO CANYON SSER 1 a
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. yielding higher natura) frequencies, if wiM requotMd ts -n.fru UM tv;A Heg loads in bracing members of the modif f td IQ See %11v criiMM ! cads wit.x adequate margins.
The floor spectra enveloping the DDE and current sc;2rf resctet were uccd go generate device location spectra by transient ans j7:s, The =ts41cer **iu tested on a shake table at the maximum expected 11tv1.
Sott aedificKlice.a.
such as strengthening of device mounts and resh~ai6ts.sre er.;es '.rd.
Ite seismic qualification of the auto / manual station wAs cciently ccmpleted te shake table testing which the f4RC staff witnessed; is'l et/=f 2,=vfie trat5rzg 13 complete. Other non-Class IE devices are being analyzed P.
atructu.*cl y
i ntegr.i ty.
Also, modifications to the mounting of $6ce non clacs 'LS <.ovicas are anticipated.
4.5.3.3 Conclusion Based on the review of the characterization of the seismic input ta O.%9 WC0 and the input to the devices located inside the MCB, review of the <ste!1ed medal of the MCB and correlation of the model properties with rstolfs of in-situ dynamic testing, attention paid to supportt and restrzinic to U*ah Class 1E and non-Class 1E devices w(thin the MCB, the staff concludre i.64; Westinghouse has performed a thorou0h investigation of the qualit) cat $6n program for the MCB, and that with the completion of all pecposed modif!ca-tions, the MCB should perform satisfactorily.
Staff acceptar.ce of tbc FCS is contingent upon written confirmation of completion of all madifications to 166 MCB including the devices with the complete qualification documentation 50s.9g l
available at a central location for staff audit.
07/20/83 8
DIABLO CANYON SSER 1 i
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f 5,3 Additional Verification Generic Concerns E.3.4 Jet Imoingenlent Effects of Postulated Pipe Ruptures Irside s
containment TM IDVP reported in its Phase I DC Quality Assurance Audit and Review Pr69r3m that specific PG&E documentatien concerning the analysis of jet r
impingement effects on components inside containment as specified in FSAR Sartion 3.6,' could noc be located. Based on this review, the IDVP issad W 7002, classified as an A/B error.
$bioeconProjectEffort la response to E0I 7002 the DCP established a program to perform a fc:6.1. analysis for. jet impingement inside containment. The purpose of 4
the DCP jet impingement analysis is to ensure that, following postulated high-energy pipe breaks inside containment, the plant can be placed in a safe shutdown condition, the consequences of the accident can be ritigate.1, and site beundary radiation exposure limits are not exceeded.
The jet impingement analysis consisted of the identification of all high-energy break locations inside containment; definition of the zone of influence in which postulated jets can cause damage; identification i
of safety-related structures, systems and components within the zone of influence; ar.d performance of safety evaluations to ensure that safety-related structures, systems, and components required to function following the postulated break are available.
i The analysis for comparents is essentially complete, and the need for codifications has been identified in only one area. The modifications will be minor, and will be either the addition of pipe restraints in the 3
area or the relocation of a few components. Modifications, if any, with respect to structures and piping systems have not yet been identified.
Independent Design Verification Program Effort The IDVP Phase 11 Program Management Plan requires that a verification t
sample be censidered in cases where pertinent documentation is not available. The IDVP selected for this sample the verification of a samole of,the DCP documentation of the jet impingement reanalysis. This t
3 verificatien was defined in ITR-34.
3 The-sample review by the IDVP was performed by the Stone and k'ebster l
Engineering Co. (SWEC).
It cceprised a> review of the DCP analysis precedure MEP-1 " Engineering Procedure for the Analysis of Jet Imp ogement Effects Inside Containment," and the DCM M-65 " Jet n
Ir:p nc,er,ent Analysis Criteria for Inside Containment"; a verification of i
the DCP implementation of the procedure, including a field walkdown; and l
review of jet-target interactions safety evaluation.
l l
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by Ro% rt L. Cloud and Associates (RLCA).
No infortnation is as yet available on the IDVP verification of the DCP review of rupture restraints inside containmant.
Ruhturerestraintsareprovidedtorestrainhighenergypipeofoneinch diameter or more. The postulated pipe break locations are detennined on the basis of the stress effects due to pressure, deadweight, thermal expansion, fluid transtents and DE during nonnal upset and test ~
conditions. High energy pipe is defined in the Diablo Canyon FSAR as pipe have a service temperature and design pressure exceeding 200 degrees Fahrenheit and 275 psig.
The DCP has conducted its evaluation of rupture restraint criteria implementation and qualification analyses through an Internal Technical Program (ITP). The purpose of the DCP evaluation was to demonstrate the adequa'cy of the as-built rupture restraints designed by Nuclear Service Coiporatinn (NSC), presently known as Ouadrex.
Tre nCP methodology was based on the selection o'f a representative sMe according to restraint configurations and piping systems. The sample was selected by grouping all the restraints specified in NSC'.s Structural Evaluation Report by configuration (30 groups) and then selecting the restraints that appear to be the critical cases.
Approximately 25 percent to 40 percent of the restraints in each group were selected for evaluation. The selection was based on member size, applied pipe rupture load, design margins, and engineering judgement.
6 For each restraint substructure selected, the corresponding U-Bolt / rod assemblies were identified and evaluated.
In addition, the DCP rethodology required evaluation of the remaining restraints in a group if a modification was required to a restraint within a specific group.
The following items were included in the DCP review:
o Comparison of as-built drawings with design drawings o
Generic studies related to the NSC Reports o
Design load verification o
Verification of the adequacy of design and construction of:
- Restraint substructure (frames)
- Building attachments (base plates and anchor bolts)
- U-Bolts / rod beams and gaps
- Restraint weldments
- Building elements (e.g., walls, columns) o Testing program for U-Bolt anchorages and couplings The DCP review calculations were tabulated on a calculation index log which grouped calculations by category: generic, U-Solt/ rod beam, substructure, and specific weld evaluation.
The IDVP selected a sample of the DCP qualification analyses to ensure conformance to criteria and accuracy of calculations. The sample was chosen to assess the essential steps of the qualification process.
-~m
s The analysis procedure was reviewed to:
o ensure that it provided the basis for a documented jet impingement
.. program o
Met the licensing commitments in FSAR Section 3.6 o
Described, a comprehensive jet impingement review program A field walkdown verified the implementation of the DCP procedure.
In addition, utilizing the DCP jet impingement revie'w results for a sample of high-energy lines, the IDVP verified the jet-target interactions of each postulated line break, and is reviewing the safety effects of each on.s'afety-related equipment.
As a result of the IDVP verification, four items of possible concern were identified and are reported in E01 8065. These items pertain to jet impingement effects on safety related piping, supports and conduit.
The DCP will perfonn a safety evaluation to resolve these items.
Safety Evaluation The effort on jet impingement effects by DCP and SWEC has as yet not been corrpleted. The approach considered by the IDVP appears to be technically adequate. However, insufficient information has been provided in the IDVP Final Report to permit a fi6a1 assessment by the Staff concerning the adequacy of the DCP corrective action or the quality of the IDVP review. This is therefore considered to be an open issue whose resolution will be reported in a supplement to this SER.
The IDVP will report a sunrnary of their findings in ITR-48. The review of this ITR will be included in the resolution of the safety issue.
We find that the DCP has not as yet satisfactorily demonstrated, nor the IDVP verified, that possible jet impingement loads were considered in the design and qualification of safety related piping and equipment inside containment. This is therefore considered an open safety issue, whose resolution will be reported in a supplement to this SER. We therefore consider the efforts by DCP and IDVP reported so far i
acceptable only for satisfaction of the requirements for Step 1, restoration of the low power license.
5.3.7 Rupture Restraints a.
IDVP Verification of the DCP Corrective Action Program The IDVP verification of the DCP Corrective Action Program for rupture restraints consists in examining the qualification of rupture restraint designs for pipe rupture loadings. The IDVP review includes field inspection to ensure conformance of design drawings to as-built conditions for selected DCP calculations.
For restraints outside containment this activity is outlined in ITR-35 and is being performed j
l
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