ML20210T267
| ML20210T267 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 09/30/1986 |
| From: | Colburn T Office of Nuclear Reactor Regulation |
| To: | Fay C WISCONSIN ELECTRIC POWER CO. |
| References | |
| NUDOCS 8610080354 | |
| Download: ML20210T267 (6) | |
Text
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SEP 3 01986 Docket Nos. 50-266 and 50-301 Mr. C. W. Fay, Vice President Nuclear Power Department Wisconsin Electric Power Company 231 W. Michigan Street, Room 308 Milwaukee, Wisconsin 53201
Dear Mr. Fay:
SUBJECT:
USE OF ENERGY ABSORBERS AS REPLACEMENT FOR SNUBBERS AT THE POINT BEACH NUCLEAR PLANT By letter dated September 3,1986 you responded to the staff's July 15, 1986 request for additional information on the above subject. As discussed with members of your staff, we have scheduled a meeting on October 17, 1986 in Room P-110 of the Phillips Building, Bethesda, Maryland to review your September 3,1986 responses.. Our contractor, Brookhaven National Laboratory, will have representatives in attendance at the meeting. We understand that your contractor, Bechtel Power Corporation, will also have representatives attending in addition to members of your staff.
Enclosed is a request for additional information that we wish to discuss at the meeting. Many of the questions are identical or similar to those already transmitted in our July 15, 1986 letter. They are enclosed here for completeness as there may be some followup discussion on these issues at the October 17, 1986 meeting. A draft set of these questions has been previously transmitted to Mr. Krause of your staff. Our formal meeting notice will be issued separately.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents, therefore, OMB clearance is not required under P.L.96-511.
If you have any questions please call me at (301) 492-9787.
Sincerely, Timothy G.
olburn, Project Manager Project Directorate #1 Division of PWR Licensing-A
Enclosure:
Request for Additional Information cc's:
See Next Page Office:
PM/ PAD #1 $uP PAD #1 Surname: TColburn/tg G
vt-Date:
09/p/86 09 Aid /86 mo188!ABt83lk P
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Mr. C. W. Fay Point Beach Nuclear Plant Wisconsin Electric Power Company Units 1 and 2 cc:
Mr. Bruce Churchill, Esq.
_Shaw, Pittman, Potts and Trowbridge 2300 N. Street, N.W.
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Washington, DC 20037 Mr. James J. Zach, Manager Point Beach Nuclear Plant Wisconsin Electric Power Company 6610 Nuclear Road Two Rivers, Wisconsin 54241 Mr. Gordon Blaha Town Chairman Town of Two Creeks Route 3 Two Rivers, Wisconsin 54241 Chairman Public Service Commission of Wisconsin Hills Farms State Office Building Madison, Wisconsin 53702 Regional Administrator, Region III U.S. Nuclear Regulatory Commission Office of Executive Director for Operations 799 Roosevelt Road Glen Ellyn, Illinois 60137 Resident Inspector's Office U.S. Nuclear Regulatory Commission 6612 Nuclear Road Two Rivers, Wisconsin 54241
r REQUEST FOR ADDITIONAL INFORMATION ON INSTALLATION OF ENERGY ABSORBERS IN PLACE OF SNUBBERS FOR POINT BEACH NUCLEAR PLANT, UNIT 1&2
REFERENCES:
1.
Wisconsin Electric Letter VPNPD-86-207, C. W. Fay to H. R. Denton,
" Dockets 50-266 and 50-301, Energy Absorbers as Replacements of Snubbers for Seismic Support of Nuclear Piping Systems, Point Beach Nuclear Plant, Units 1 and 2",
dated May 13, 1986, 2.
" Reanalysis of Main Steam Line Outside Containment with Energy Absorbers as Replacements for Hydraulic Snubbers for the Point Beach Nuclear Plant", prepared by Bechtel Power Corporation (Enclosure 1 to Ref. 1).
3.
M. Z. Khlafallah and H. M. Lee, " Technical Basis for the Use of Energy Absorbers as Supports of Nuclear Power Plant Piping Systems", Bechtel Power Corporation, January, 1985 (Enclosure 2 to Ref. 1).
4.
M. Z. Khlafallah and H. M. Lee, " Technical Basis for the Use of Energy Absorbers as Supports of Nuclear Power Plant Piping Systems," (Proprietary Version), Bechtel Power Corporation, January, 1983.
QUESTIONS:
Analytical Methodology 1.
Provide step by step description regarding application of the analytical methodology to the sample problem in Reference 2.
Provide detailed input information (geometry, material properties, loads, etc.) and all calculations required for each step in the process from snubber removal and energy absorber (EA) installation to final evaluation.
2.
Provide additional information on the method for extrapolating design response spectra curves to higher damping values including the method used to generate the response factor curves in Fig. 6.2. of Reference 4.
3.
Describe the methods that are used to analyze other dynamic loads such as normal vibration and water hammer.
4 Section 6.4 of Reference 4, states that EA's may yield under thermal expansion conditions.
Can they also yield under dead weight conditions?
Will the nonlinear stiffness characteristics be modeled for the piping static load cases?
5.
Define the stress-strain and hysteresis curves used to define the EA properties. Are these curves best estimate, upper bound or lower bound?
Are they based on specific EA material tests?
6.
In computing piping system frequencies, is the effect of damping included? Can this be significant for large values of damping?
7.
Since damping is highly dependent on the accurate calculation of dynamic displacements at EA locations, will additional safety factors be included to address uncertainties in material properties and modeling techniques?
Fatigue Considerations 8.
Considering the wide scatter of test data normally observed in developing fatigue curves, why is a safety factor of only 1.5 considered sufficient for the design fatigue curves? The ASME code Appendix I fatigue curves use a minimum safety factor of 20 on cycles.
9.
Will normal operating vibration loads be considered in the fatigue evaluation of EA's?
- 10. Section 1.2 states that the EA's allow piping systems to accommodate higher than design earthquake loads.
In light of the low safety factor on fatigue, how can this be justified?
Damping 11.
Equivalent viscous damping factors calculated by equation 5-4 of Reference 4 are based on a steady state sinusoidal motion assumption.
Justify the application of these equivalent damping factors to transient loads.
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- 13. How is damping due to EA plastic dcformation combined with pipitig material damping?
14.
How do changes in the hysteresis curves due to cyclic thermal loads affect EA damping?
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Design Considerations
- 15. Will high temperature piping affect the operating temperature of EA's?
If so, are EA material properties affected?
- 16. Will EA's be exposed to long term radiation which could affect their material properties?
- 17. Since snubber removal will change the dynamic characteristics of the piping systems, will each system be monitored for changes in normal operating vibrations?
- 18. Can multidirectional loads be transmitted through EA's.
If so, how are the off direction loads considered in the analysis?
- 19. Since a piping system with EA's can be expected to have larger seismic displacements than one with snubbers, will potential interactions with adjacent equipment and structures be checked?
__Reaulatory Guide 1.84 Requirements
- 20. Provide a list of piping systems in the plant in which the EA's will be used.
Test Correlations
- 21. Section 4.5(b) of Reference 4 demonstrates the need to calibrate the frequency and damping parameters of the piping model to achieve accurate results. -Will the calibration be applied on a production basis? If not, provide justification.
22.
Figures 5.5 and 5.9 show that linear analysis can underpredict response.
How will this potential underprediction be accounted for in production runs? Do the sample problems represent worse cases or can more significant underprediction be possible?
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