ML20236X771
| ML20236X771 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/06/1998 |
| From: | Thadani M NRC (Affiliation Not Assigned) |
| To: | Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| TAC-M99465, TAC-M99466, NUDOCS 9808100247 | |
| Download: ML20236X771 (5) | |
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August 6, 1998
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Mr. Garrett D. Edwards Director-Licensing, MC 62A-1 PECO Energy Company Nuclear Group Headquarters Correspondence Control Desk P.O. Box 195 Wayne, PA 19087 4195
Dear Mr. Edwards:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION (RAl) REGARDING FLOOR RESPONSE SPECTRA FOR REPLACEMENT RECIRCULATION PIPING SYSTEMS, PEACH BOTTOM ATOMIC POWER STATION (PBAPS), UNITS 2 AND 3 (TAC NOS. M99465 AND M99466)
Dear Mr. Edwards:
During a telecon on February 22,1998, the Nuclear Regulatory Comrnission (NRC) sta#
discussed with the PECO Energy Company's (the licensee) sta# an issue related to the seismic adequacy of Peach Bottom Atomic Power Station (PBAPs), Units 2 and 3, replacement recirculation piping. During the telecon, the NRC staff requested adddional information, and the licensee indicated that it would provide its response in a followup telecon. The licensee subsequently informed the NRC Project Manager that the NRC staff should provide the licensee with an RAI, so that it can provide the information that is responsive to the NRC staff's needs.
Accordingly, the staff hans prepared the enclosed RAI for the licensee's response. The staff requests that the licensee provide its response to the enclosed RAI within 45 days from the receipt of this letter.
Should you have any questions regarding this request, please contact me on (301) 415-1476.
Sincerely, Mcb C. Thadani, Senior Project Manager Project Directorate 1-2 Division of Reactor Projects -I/ll Office of Nuclear Reactor Regulation Docket Nos. 50-277 and 50-278
Enclosure:
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WASHINGTON, D.C. 30sewcot August 6, 1998 Mr. Garrett D. Edwards Director-Licensing, MC 62A-1 l
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Nuclear Group Headquarters Correspondence Control Desk P.O. Box 195 Wayne, PA 19087-0195 Duar Mr. Edwards:
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SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION (RAl) REGARDING FLOOR RESPONSE SPECTRA FOR REPLACEMENT RECIRCULATION PIPING SYSTEMS, PEACH BOTTOM ATOMIC POWER STATION (PBAPri LINITS 2 i
AND 3 (TAC NOS. M99465 AND M99466)
Dear Mr. Edwards:
During a telecon on February 22,1998, the Nuclear Regulatory Commission (NRC) staff discussed with the PECO Energy Company's (the licensee) staff an issue related to the seismic adequacy of Peach Bottom Atomic Power Station (PBAPs), Units 2 and 3, replacement recirculation piping. During the telecon, the NRC staff requested additionalinformation, and the I
licensee indicated that it would provide its response in a followup telecon. The licensee subsequently informed the NRC Project Manager that the NRC staff should provide the licensee with an RAI, so that it can provide the information that is responsive to the NRC staff's needs.
Accordingly, the staff has prepared the enclosed RAI for the licensee's response. The staff requests that the licensee provide its response to the enclosed RAI within 45 days from the receipt of this letter.
Should you have any questions regarding this request, please contact me on (301) 415-1476.
Sincerely, N
Mohan C. Thadani, Senior Project Manager Project Directorate 1-2 Division of Reactor Projects - t/ll Office of Nuclear Reactor Regulation Oocket Nos. 50-277 and 50-278
Enclosure:
RAI cc w/ encl: See next page l
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4 Mr. Garrett D. Edwards PECO Energy Company Peach Dottom Atomic Power Station, Units 2 and 3 cc:
J. W. Durham, Sr., Esquire Sr. V.P. & General Counsel Chief-Division of Nuclear Safety PA Dept. of PECO Energy Company Environmental Resources 2301 Market Street, S26-1 P.O. Box 8469 Philadelphia, PA 19101 Harrisburg, PA 17105-8469 PECO Energy Company ATTN: Mr. T. N. Mitchell, Vice President Board of Supervisors Peach Bottom Atomic Power Station 1848 Lay Road Peach Bottom Township R.D.#1 Delta, PA 17314 Delta, PA 17314 PECO Energy Company ATTN: Regulatory Engineer, A4 SS Public Service Commission of Maryland Engineering Division Peach Bottom Atomic Power Station 1848 Lay Road Chief Engineer 6 St. Paul Centre Delta, PA 17314 Baltimore, MD 21202-6806 Resident inspector Mr. Richard McLean U.S. Nuclear Reguls. tory Commission Power Plant and Environmental Peach Bottom Atomic Power Station Review Division P.O. Box 399 Department of Natural Resources Delta, PA 17314 B-3, Tawes State Office Building Annapolis, MD 21401 Regional Administrator, Region i U.S. Nuclear Regulatory Commission Dr. Judith Johnsrud 475 Allendale Road National Energy Committee King of Prussia, PA 19406 Sierra Club 433 Orlando Avenue Mr. Roland Fletcher State College, PA 16803 Department of Environment 201 West Preston Street Manager-Financial Control & Co-Owner Baltimore, MD 21201 Affairs Public Service Electric and Gas A. F. Kirby,111 Company L
Extemal Operations - Nuclear P.O. Box 236 Delmarva Power & Light Company Hancocks Bridge, NJ 00038-0236 P.O. Box 231 Wilmington, DE 19899 Manager-Peach Bottom Licensing PECO Energy Company PECO Energy Company Nuclear Group Headquarters Plant Manager Correspondence Control Desk Peach Bottom Atomic Power Station P.O. Box No.195 1848 Lay Road Wayne, PA 19087-0195 Delta, PA 17314 l
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REQUEST FOR ADDITIONAL INFORMATION REGARDING DEVELOPMENT OF THE FLOOR RESPONSE SPECTRA REPLACEMENT RECIRCULATION PlPING SYSTEM PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3 l
t Modified Housner ground response spectra (GRS) with a Zero Period Acceleration (ZPA) of l
0.12g are the bconsing design basis GRS for the Safe Shutdown Earthquake (SSE) at Peach i
Bottom, Units 2 and 3 as described in the Updated Final Safety Analysis Report (UFSAR).
PECO Energy Company (the licensee) indicated in the report (Reference 1) that the piping analysis results exceeded the ASME Code allowables when the licensing design basis GRS with
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0.5 percent of critical damping were used as input applied at the base of the structure.
l Consequently, the hcensee reanalyzed the piping responses using the Regulatory Guide (RG) 1.60 GRS with ASME Code Case N-411 damping to demonstrate the adequacy of the piping integrity under an SSE condition. However, the report (Reference 1) submitted for soview regarding the development of floor response spectra (FRS) for the seismic analysis does not contain sufficient technical information. The licensee is requested to provide responses to the following questions:
- 1. Reference 1 indicates that a single set of artificial time histories (two horizontal and one vertical components) were developed from the RG 1.60 GRS. Demonstrate the adequacy of the artificial time history including the extent of conformance to the target power spectral 4
density (PSD) function of the artificial time history. Provide the actual and target PSDs.
- 2. Is the developed time history applied directly at the base of the structure (Mass point 41 in Figure E1 of Reference 1)? Indicate whether any deconvolution technique is used to reduce the amplitude of the SSE from the ground surface to the base of the structure.
- 3. Provide the time history input data applied at the base of the structure in ASCll format on a
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3.5-inch diskette.
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- 4. You indicate in Reference 1 that the calculated stresses exceeded the ASME Code allowables when a time history, generated using the GESSAR method, was used. Therefore, you regenerated a new time history using the SCOTH method.
a) Explain the difference between the GESSAR and SCOTH methods.
b) Demonstrate the validity of the SCOTH method.
- 5. With respect to the development of the FRS, provide the following:
l a) Indicate whether you accounted for any soil-structure interactions.
l b) Indicate whether you applied the vertical time history at the base of the structure, l
c) It appears that you made one assumption that the structure is rigid, thereby, there is no f
amplification at higher elevation due to the vertical seismic motion. You assumed that the f
vertical spectrum applied at the base of the structure is the same as the FRS at any elevation. Based on the structural model provided in Reference 1, the staff does not agree with your assumption. Provide detailed technicaljustifications for your assumption.
d) What was the structural damping value used?
e) Provide generated time histories for the Mass points (41,39,37,34,42,29,27,43,51, 45,58,44,1,12,9,24,47,48 and 49) in Figure Ei of Reference 1 in ASCil fony,at on a 3.5-inch diskette and hard copies of their corresponding FRS.
ENCLOSURE
- 6. The structural model (Figure E1 of Reference 1) used for the piping analysis is different to the structural model (Figure 1 of Reference 2) used for PECO's shroud repair analysis. In the structural model (Reference 1), some of the horizontal masses are lumped on the vedical stick model, thereby reducing the vertical and eccentncdy effects. The structural model for the shroud repair analysis (Reference 2) appears to be more realistic. Explain the reasons for using the different structural model in the piping analysis and demonstrate that the model of Reference 1 is as appropriate as the model of Reference 2.
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References:
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- 1. " Peach Bottom 2 & 3 - Recirculation Piping Reanalysis, Uniform Support Motion, Seismic Response Spectra Based on Regulatory Guide 1.60 Free-Field Earthquake and ASME Code Case N-411 Damping," NEDC-32790, DRF B33-00293, Section 15, Class 2, GE Nuclear Energy, October 1997.
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- 2. " Shroud Mechanical Repair Program: Peach Bottom Units 2 & 3 - Seismic analysis "
l GENE-77160-0994, DRF B13-01732, Rev. 2, Class Ill, GE Nuclear Energy, June,1995.
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