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UNITEb STATES f
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NUCLEAR REGULATORY COMMISSION i
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E WASHINGTON. D. C. 20655 s
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g-y JUL 2 S E63 MEMORANDUM FOR:
R. Vollmer Director, Division of Engineering-R. Mattson, Director, Division of Systems Integration J. Martin, Regicnal Administrator, Region V J. Taylor. Director, Division of Quality Assurance, Safeguards, Inspection Program IE E. Christenbury Hearing Division, Director & Chief Counsel FROM:
D. G. Eisenhut, Director, Division of Licensing, NRR
SUBJECT:
REVIEW OF DIABLO CANYON SER SUPPLEMENT ON VERIFICATION EFFORT Attached is the draft SER (Supplement 18) for the Diablo Canyon verification effort. The Comission's overall schedule for SEP issuarce, review by the parties, meetings, etc. identified August 5 (next Friday) as the latest issue date for the Supplement. We request that you review the draft and provide us with your coments by noon Monday, August 1.
Any later coments most likely cannot be incorporated in the issued version.
At this time there are a number of items, mainly in Section 4, where PG&E has comitted to some follow-up action (e.g. update FSAR, revise drawings).
We do not consider them open. items but will list them in the report.
cN There are also t.enty open items in the SER. Section 4 contains two open
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issues related to E0I S010 and E0I 8047.
In Section 3,18 cpen issues have been identified; they have been sunnarized in the attachment to this memo.
For each open issue, the sponsoring Division is requested to indicate whether resolution of the issue is a prerequisite to a staff recomendation supporting reinstatement of the license. Your bases should be technical in nature, as l
the Comission's Order recognizes that certain items can be resolved following t
l reinstatement.
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o Darrell G'. Eisenhut Director Division of Licensing l
Office of Nuclear Reactor Regulation
Enclosures:
As Stated l
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The review by the Diablo Canyon Project resulted in many modifications to the structure.
The bulk of the modifications were in the annulus structural steel structure where beams and connections were stiffened to raise,the natural frequency so that the original qualification of equip-ment piping was valid and the fuel handling building where members were added to the bracing in the roof structure.
The IDVP verification effort consisted of verifying the as-built structure against design drawings, reviewing the design calculations, making independent calculations where necessarf, revieqing the DCP calculations and verifying the field modifications.
The staff' finds the organization and execution of these tasks to be in keeping with good engineering professionalism and the exercising of sound engineering judgment.
The DCP review effort consisted of verifying the as-built configuration of the structure against the design drawings, reanalyzing the plant and comparing the results with the Hosgri, DE and DDE evaluations. Tne results of the calculations and parametric studies were revieweo by the IDVP.
In general, the staff finds that the 10VP ver.ification if followed to a
closure should lead to the conclusion the plant is currently built in conformance to the licensing criteria or idnetify areas where it is not in conformance.
Although the IDVP review is not yet complete, and the final report has been published, the staff finds the following items to be of concern; 1.
Averaging of the floor response spectra peaks and valleys should reflect a true average and not a lower bound as found in some cases.
The use of averaged spectra should be limited to frequencies away from the structural frecuencies.
2.
The use of a 20 Hz cut off frequency as the criteria for defining rigidity of structural members should be verified and/or justified.
3.
The use of the AISC code in evaluating the equipment hatch area in the containment shell is in violation of the FSAR comittment to use the ASME Code Section III.
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The use of a matherratical-model, with its inher6nt assumptions, to produce seismic loads in'a structure and the use of another model with different assufrptions to. analyze the structural rembers is not consistent and justification should te provided.
5, The evaluation of the Auxiliary Building used two different versions of the ACI 318 code and a modification to the codes contained in Appendix 2A of the DCP final report. The use of the-different. versions and the modification should be evaluated by the IDVP.
6.
The discrepancy between the IDVP and the DCF on the influence of the soil springs used in the Auxiliary Building seismic model should be resolved and documented.
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The use of dynamic degrees'of freeoom reduction methods for the seismic modelt should be evaluated to show that'no serious errors have been introduced into the member loads.
8.
The use of the translation and torsional response of the Auxiliary Building as input to the fuel handling building'and the neglectin'g of accidental torsion in the seismic model should be justified and any parametric studies should be provided and documented.
9.
It should be verified that all supports of the reviewed piping satisfy the required allowable. loads 'or stresses because of the number of support modification.
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- 10. The IDVP should repeat the calculations for the piping systems
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analyzed -in ITR's 12 and 17 with the present support configurations l
and the current loading, and verify that the piping, equipment and supports satisfy all correspending design criteria.
In addition-
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the IDVP should also verify the analysis of a specific piping e
system subjected to load combinations which include thermal loads.
- 11. The IDVP should provide the results and resolutions of IDVP concerns relative to the qualification of small bore piping and
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- 12. The extreme fiber stress in the valve nozzles to pipe interface has t
not been specifically addressed in any of the piping systems. This i
i subject should be addressed as part of the IDVP verification of the DCP corrective action plan.
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- 13. All of the mechanical equipment has not been requalified as shown in Table 2.3.1-1 of the DCP Final Report.
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- 14. 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 all safety related piping and equipment inside containment.
15.
The DCP has not as yet satisfcctorily reviewed nor the IDVP verified, that the rupture restraints outside and inside containment have been properly designed and installed to provide protection against postulated ruptures in high pressure piping.
- 16. The total lateral' force, total resistance.to sliding and the factor of safety against sliding of. the intake structure.has not been fully evaluated. 'This information will have to be provided before the stability of the intake structure can be verified.
.17.
The buried diesel fuel tanks need to be investigated more fully.
The modeling method of the fluid inside the tank was inappro-priately modeled and various levels of fluid were not considered.
The representation of the surrounding soil did not incorporate the most critical section. The tanks should be evaluated correcting the above deficiencies in the current,models.
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