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c SEP 2 tyy Docket Nos.: 50-275/323 MEMORANDUM FOR: John F. Stols, Chief, Light Water Reactors Branch No. 1. DPM FROM:
R. J. Bosnak, Chief, Mechanical Engineering Branch, DSS
SUBJECT:
SEISMIC REEVALUATION OF DIABIA CANYON SITE, UNITS 1 & 2 Plant Name Diablo Canyon Site, Units 1 & 2 Licensing Stage: FSAR Docket Noe 50-275/323 Responsible Branch & Project Managers LWR-1, D. Allison Responsible SS Branch & Teehnie=1 Reviewers MEB, P. Y. Chen and E. Sullivan Description of Response Preliminary Questions on Amandment No. 50 to Operating License.
Review Status: Awaiting information.
The Mechanical Engineering Branch, DSS', has reviewed the Amendment 50 to the subject FSAR. This amenAmant consists of a report entitled " Seismic Evaluation for Postulated 7.5 M Hoegri Earthquake." Adequate responses to the enclosed request for additional information are required before we can complete our evaluation.
About four weeks before our seismic audit, we will send you a list of items which we would like to have the applicant address during our audit.
R. J. Bosnak, Chief Hechanical Engineering Branch Division of Systems S4fety cct R. J. Hattson, DSS DISTRIBUTION:
J. P. Knight, DSS Docket File 50-275/323 D. Ross, DSS NRR Reading File R. Tedesco, DSS DSS MEB Reading File T. Novak, DSS V. Benaroya, DSS
- 1. Sihweil, DSS H. J. Brammer, DSS D. Allison, DSS 772210377 E. Sullivan, DSS 8600M0186 G60 ant P. Y. Chen, DSS PDR FOIA HOUGH 96-T11 P DI' A
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l 110.0 MECHANICAL ENGINEERING BRANCH 110.1 In assessing the design adequacy of piping, other pressure retaining components and their supports, the combination of loads due to Hosgri earthquake and the loss of coolant accident (LOCA) has to be considered. In the subject report, however, this effect was not considered. Submit the results of your analysis which consider the effects of combining the normal operating loads, the earthquake loads, and the LOCA loads. Explain and justify the method for load combination.
110.2 The definition of " rigid piping" defined in Section 2.2.3.3 is not consistent with that defined in Section 2.2.3.5.
Clarify the definition used and provide the basis.
110.3 The definition of " Rigid Equipment" as given in Section 2.2.3.3 is not consistent with the definition used in the IEEE standard-344, 1971 or 1975.
1.
Provide a listing of mechanical and electrical equipment having any natural frequencies in either the vertical n90$4@
direction or either of the two horizontal directions less than 33 Hz which were considered to be rigid. Note that the mechanical and electrical equipment stated here should not be limited to only those presented in Chapters 7 and 10.
2.
List the natural frequencies of the equipment in 1 and their corresponding directions.
3.
Demonstrate that the equipment listed meets the qualifi-cation requirements of the IEEE Standard-344, 1975.
110.4 In Section 2.3.4, it was mentioned that seismic capability of some of the equipment was determined by impact testing (drop hammer), centrifugal test, and engineering judgement.
Identify all such equipment and demonstrate that the qual-ification method is adequate for the Hosgri earthquake.
110.5 In relation to the material presently contained in Amendment 50, provide supplementary information to demonstrate that all seismic Design Class I Systems and components and those Design Class II and III components, which are either necessary for cold shutdown or are safety related, are qualified for the Hosgri earthquake.
110.6 In Table 5-2 of the Amendment 50 to the FSAR, 3.6 S was h
used for faulted condition stress limits for Class A piping.
- ovide the rationale and justification for the inac of
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- h 110.7 In view of the steam generator problems (e.g., denting of
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tubes and cracking of tube supports) recently occurring in the Westinghouse supplied nuclear power plants, what measures have PC & E as! Westinghouse taken to minimize the possibility of these problems occurring in the steam gener-ators used in Diablo Canyon Units 1 & 2.
The mathematical model of the reactor laternals used for 110.8 seismic analysis was different from that for the loss of coolant accident (LOCA) analysis (specifically referring to the core barrel upper support condition). Justify the ade-quacy of each of these two different mathematical models for the same structure.
110.9 Section 7.4.2 states that the flexible supports under the diesels were removed to satisfy seismic requirements. Demon-strate that the current design has adequately considered vibration resulting from diesel operation.
110.10 In Section 7.4.4, it was stated in page 7-14 that, as part of the Hosgri evaluation, a vibration test was conducted to determine the lowest natural frequency of the Component Cooling M
Water Heat Exchangers. Present the test, test results and
, analysis results in a more complete fashion.
110.11 Demonstrate that the main steam safety valves are seismically i
qualified for the Hosgri earthquake.
110.12 Amendment 50 to the FSAR indicates that certain types of piping have been supported by the use of seismic restraint spacing criteria.
(1) Provide verification of the adequacy of the piping and supports designed using the original spacing criteria by submitting the results of sample computer analyses of actual plant piping with multiple supports between physical pipe anchors, subjected to the Hosgri earthquake excitation. These sample analyses should include elbow and tees for which the spacing criteria on page 2-11 of Amendment 50 was applied.
s (2) Provide similar calculations as in (1) but using the actual stiffness of the supports which have a first mode natural frequency of about 20 Hz.
110.13 Recent field experience has indicated that defective snubbers have been found in nuclear power plants which would result in both the failure of these snubbers to restrain the attached I
piping or equipment during a dynamic transient event and the locking of snubbers during plant normal operation. The following information on the subiect of single active snubber failure should be submitted:
- 1) PG & E should provide the results of analyses performed
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v 110-3 to determine the maximum response which would result from the single active failure of any snubber (including those used in tanden) in a system. Dynamic and thermal expansion analyses of several systems should be conducted and should include for example the Reactor Coolant Loop with snubbers attached to the primary equipment, Main Steam Line inside containment, and portions of the RHE and Auxiliary Feed Water Systems.
- 2) PG & E chould evaluate the ability of a maintenance and inspection program to reduce the probability of single active failure of a given snubber to an acceptable level, 110.14 In Section 10.3.21, it was stated that Unit 1 safeguard relay panelboard was tested by Wyle Laboratories and Unit 2 panelboard was tested at the vendor's plant. It was noted that the test inputs used for Unit 2 panelboard were quite different from those for Unit 1.
Explain the differences in structural characteristics of these two panelboards, if any, and the reason for using the different inputs. Demonstrate that the Unit 1 panelboard is qualified for the Hosgri earthquake.
ggHmp3 110.15 The topical report (WCAP 8941, Feb.1977), " Seismic Qualifica-tion of the Rotary Relay for use in the Trojan and Diablo Canyon Auxiliary Safeguards Cabinets", has not been reviewed by the NRC Staff. Submit the report in time for review before the scheduled seismic audit.
110.16 Verify that the following Westinghouse topical reports as referenced in Amendment 50 are applicable for use in Diablo Canyon Units 1 & 2, under the Hosgri earthquake excitation (final spectra):
WCAP 8021 WCAP 8674 (WCAP 8673)
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