ML18051A837
| ML18051A837 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 04/03/1984 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0820, RTR-NUREG-820, TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8404060231 | |
| Download: ML18051A837 (4) | |
Text
consumers Power company General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-0550 April 3, 1984 Dennis M Crutchfield, Chief Operating Reactor Branch No 5 Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - SEISMIC DESIGN CONSIDERATIONS, SEP TOPIC III-6 (NUREG-0820, SECTION 4.10)
In a letter to Consumers Power Company dated September 6, 1983, the NRC requested that further evaluation be performed on specific seismic design issues.
These items were summarized in Section 2.4 of the "Integrated Plant Safety Assessment Report Supplement," dated November 7, 1983.
The items of Section 2.4 of the supplement are listed below, followed by Consumers Power Company's response.
Item 1 The licensee should either reevaluate the seismic issues using the site-specific spectrum as the input ground motion or demonstrate that there is enough margin inherent in the equipment design to make up the difference between the site-specific spectrum and the 0.2 g Housner ground response spectrum used by the licensee.
Response To Item 1 The principal seismic and geological considerations required for nuclear power plant design are governed by 10 CFR 100, Appendix A.
The criteria set forth in 10 CFR 100, Appendix A, can be met by using either; (1) the site-specific spectra or, (2) the guidelines of Regulatory Guide 1.60.
The independent evaluation made in NVREG/CR-1833, "Seis~ic Review of the Palisades Nuclear Power Plant as part of the Systematic Evaluation Program," dated January 19, 1981, showed that the floor response sp~ctra developed originally, based upon modified-Taft spectra, for use in the Palisades Plant equipment qualification, did not deviate from the NUREG/CR-1833 curves significantly.
Specifically, current acceptance criteria (NUREG/CR-0098, "Development of Criteria for Seismic Review of Selected Nuclear Power Plants"), permit higher damping values and the spectra in general have lower peak responses.
OC0484-0002AA-NL02 8404060231 840403 PDR ADOCK 05000255 p
~MCrutchfield 9 Chief Palisades Plant SEP TOPIC III-6 April 3, 1984 Response To Item 1 (Continued) 2 Subsequent efforts made by Consumers Power Company in response to the open issues listed in Enclosure 2 of NUREG/CR-1833 showed that the essential mechanical equipment, which qualified under the original Palisades response spectra, meets the current criteria of NUREG/CR-0098.
Item 2 The licensee should either show that the effect of the additional amplification of the equipment response (resulting from out-of-plane vibration of floors and walls) is negligible or demonstrate that the equipment can withstand the additional seismic loads without affecting its structural loads.
Response To Item 2 Even though floor flexibility was not considered in the original seismic analysis, floor flexibility is not expected to have a great effect for the heavily loaded reinforced concrete slabs which have relatively higher damping values (NUREG/CR-0098).
Sample evaluation of the plant equipment (see Item 1), based upon Palisades original floor response spectra and the method stipulated in the FSAR, indicates that the concern over out-of-plane amplification is not warranted.
For a heavy reinforced concrete bearing wall, with high in-plane force, the out-of-plane amplification is also negligible.
Item 3 The license should submit evaluation results for control room panels C-llA and C-126 and switchgear lD.
Response To Item 3 The structural evaluation of panel C-126 was performed for Consumers Power Company by Stevenson & Associates.
The evaluation, "Seismic Structural -
Integrity Evaluation of Panels C-125, C-126, and C-106 at Palisades Nuclear Power Plant," considered the structural capacity of the load carrying elements of the panels and the capacity of the base anchorage.
A static equivalent analysis was performed using 1.5 times the peak of the original Palisades 5% damped response spectra at elevation 625' -0 of the Auxiliary Building for the Design Basis Earthquake (DBE).
The resulting accelerations are 2.76g horizontal and 0.3g vertical.
The vertical acceleration includes an amplification factor to account for floor flexibility.
Two load combinations were considered:
OC0484-0002AA-NL02
DMCrutchfield, Chief Palisades Plant SEP TOPIC III-6 April 3, 1984 Response To Item 3 (Continued)
- 1.
D + L +
- 2.
D + L +
D L
SHX SHY sv 3
SHX + SV SHY + SV Dead Load Live Load Horizontal DBE in the x-direction Horizontal DBE in the y-direction Vertical DBE The acceptance criteria is based on 1.6 times the AISC or AISI Code allowable stresses.
Results of the analysis indicate that all the structural components above the base meet the requirements of the acceptance criteria for the postulated DBE.
The base anchorage of panels C-126 and C-106 were found to be inadequate.
Design modifications have been prepared and installation is scheduled for the 1985 Refueling Outage.
The anchorage of subcomponents (internal electrical devices) within control panel C-126 were evaluated for their ability to withstand the Palisades design basis earthquake.
A static equivalent analysis was performed using 1.5 times the peak of the original Palisades 5% damped response spectra at elevation 625'-0 of the Auxiliary Building for the design basis earthquake.
The accelera-tions used in the anchorage analysis are:
- 1.
Horizontal out-of-plane -
4.47g
- 2.
Horizontal in-plane - 2.76g.
- 3.
Vertical - 0.63g The horizontal out-of-plane acceleration includes a participation factor of.;;~
to account for increased displacement due to accelerated load which results ln an increased applied force and the vertical acceleration includes an amplifica-tion factor of 1.3 to account for floor flexibility.
The load combinations and acceptance criteria are the same as used for the structural integrity evaluation of C-126.
Results of the analysis indicate that all the subcomponent anchor systems meet the requirements of the acceptance criteria for the postulated design bases earthquake with the safety factor of 1.1 or greater except for two Fischer Porter chart recorders.
For these two instruments stiffness and frequency calculations were made which resulted in the anchorage surviving the DBE with a safety factor of two.
OC0484-0002AA-NL02
I I
DMCrutchfield, Chief Palisades Plant SEP TOPIC III-6 April 3, 1984 Response To Item 3 (Continued) 4 Panel C-llA was recently installed in the Palisades control room.
A dynamic analysis of the cabinet structure was performed by Analytical Engineering Associates, Inc.
The analysis, "Seismic Structural Analysis of As-Built Control Panel C-llA Palisades Power Plant", utilizes a finite element computer model composed of beam and plate elements.
The computer run demonstrates the first mode resonant frequency is 18.2 hertz which places the panel response in the rigid range.
The resulting accelerations, obtained from the Palisades 0.5% damped response spectra elevation 625'-0 for safe shutdown earthquake, are 0.5g horizontal and 0.14g vertical.
Cabinet structure element loads, including base anchors, were combined using square root sum of the squares for the three directions.
Stresses were calculated and compared with 90% of the material yield stresses.
All elements were found to have a safety factor of 1.1 or greater for safe shutdown earth-quake.
Item 6 The licensee should develop a plan and schedule to implement the generic cable tray evaluation guidelines developed by the SEP Owners Group.
Response To Item 6 Seismic evaluation of electrical raceway systems is in progress.
A definite plan and schedule will be submitted 30 days after receipt of the plant specific Safety Evaluation Report, as stated in our letter dated December 29, 1983.
Item 4, "Qualification of Control Panel C-33," and Item 5, "Vertical Component of Acceleration Used for Evaluation of Internal Device Anchorage of MCC 1 and 2," are undergoing further evaluation.
The evaluation of Items 4 and 5 will be completed after NRC review of Items 1 and 2 above, since the results of the NRC review will affect the evaluation of Items 4 and 5.
Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC0484-0002AA-NL02