ML17306B276
| ML17306B276 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/09/1993 |
| From: | Trammell C Office of Nuclear Reactor Regulation |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| GL-88-20, TAC-M83654, TAC-M83655, TAC-M83656, NUDOCS 9302120138 | |
| Download: ML17306B276 (17) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 February 9,
1993 Docket Nos.
50-528, 50-529 and 50-530 Hr. William F.
Conway Executive Vice President, Nuclear Arizona Public Service Company Post Office Box 53999
- Phoenix, Arizona 85072-3999
SUBJECT:
NRC REVIEW RESPONSE TO SUPPLEMENTAL RESPONSE TO GENERIC LETTER 88-20, SUPPLEMENT 4, PALO VERDE NUCLEAR GENERATING STATION (TAC NOS.
- M83654, H83655, AND H83656)
Dear Hr. Conway:
By letter dated December 26, 1991, Arizona Public Service Company (APS) requested that the review level earthquake (RLE) for Palo Verde Nuclear Generating Station (Palo Verde) be changed from 0.5g to 0.3g stating that, based on its own study, the seismic hazard for Palo Verde can be shown to be consistent with the seismic hazards for 0.3g sites east of the Rocky Mountains.
In a letter dated June 17, 1992, the NRC staff concluded that the information provided by APS was not adequate to justify the reduction in RLE, and noted that further pursuit of this request would require a relatively large number of additional studies in order to capture a range of opinions in the earth science community.
Since December
- 1991, APS has performed additional seismic hazard analyses.
In a letter dated August 4,
- 1992, APS submitted a supplemental seismic hazard analysis and requested additional review.
APS also requested to delay the submittal date for the seismic portion of the individual plant examination of external events (IPEEE) to June 1995.
The NRC staff has reviewed these additional materials and concluded that the IPEEE submittal date can be delayed to June 1995 as requested; but the request for a reduction of the RLE at Palo Verde from 0.5g to 0.3g can not be approved at this time because the information provided is not adeouate to justify such a reduction.
Lacking additional information the NRC staff concludes that the original position, 0.5g RLE for Palo Verde site, should be maintained.
If APS desires to pursue this request further, the NRC staff requests that additional questions and seismic hazard sensitivity studies, as outlined in the enclosure, be provided for staff review.
APS should be warned at this time that the results of those studies may show that the seismic hazard at Palo Verde to be higher than what was presented in the August 4, 1992 submittal.
The NRC staff wants to emphasize again that a 0.5g RLE does not represent a threshold for vulnerability; a 0.5g RLE was selected to help APS determine which potentially important components,
- systems, and structures associated with potential functional sequences and functional failures should be reported to the NRC in the IPEEE submittal.
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Mr. William F.
Conway February 9,
1993 As you are aware, we have scheduled a meeting to be held on Tuesday, February 16,
- 1993, 9:00 am until 12 noon, to discuss the request for additional information and establish a schedule for a response.
The meeting will be held in room 2F21 of the One White Flint North building.
This request for information affects fewer than 10 respondents.
Therefore, it is not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact us should you have any questions regarding this request.
Sincerely,
@Charles M. Trammell, Sr. Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Request for Additional Information cc w/enclosure:
See next page
Hr. William F.
Conway February 9,
1993 As you are
- aware, we have scheduled a meeting to be held on Tuesday, February 16,
- 1993, 9:00 am until 12 noon, to discuss the request for additional, information and establish a schedule for a response.
The meeting will be held in room 2F21 of the One White Flint North building.
ll This request for information affects fewer than 10 respondents.
Therefore, it is not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact us should you have any questions regarding this request.
Enclosure:
Request for Additional Information cc w/enclosure:
See next page DISTRIBUTION:
Sincerely, Original signed by:
Linh N. Tran for:
Charles M. Trammell, Sr. Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
", Docket File JRoe DFotser
- OGC, (15B18)
- KPerkins, RV NRC 5, Local PDRs HVirgilio CTrammell
- ACRS, (10) (P315)
PDV Reading File TQuay LTran PDV Plant File DATE F93 OFC PDV/LA NAME DFoste PDV PH LTran N 8-0 93 PDV PH CTrammell Nc 93 PDV/D TQuay 93 OFFICIAL RECORD COPY DOCUMENT NAME:
PV83654.LTR 1
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Hr. William F.
Conway Arizona Public Service Company Palo Verde CC:
Nancy C. Loftin, Esq.
Corporate Secretary 8 Counsel Arizona Public Service Company P. 0.
Box 53999, Mail Station 9068
- Phoenix, Arizona 85072-3999 James A. Beoletto, Esq.
Southern California Edison Company P. 0.
Box 800
- Rosemead, California 91770 Senior Resident Inspector U.S. Nuclear Regulatory Commission HC-03 Box 293-NR
- Buckeye, Arizona 85326 Regional Administrator, Region V
U. S. Nuclear Regulatory Commission 1450 Maria Lane Suite 210 Walnut Creek, California 94596 Hr. Charles B. Brinkman, Hanager Washington Nuclear Operations ABB Combustion Engineering Nuclear Power 12300 Twinbrook Parkway, Suite 330 Rockville, Maryland 20852 Hr. William A. Wright, Acting Director Arizona Radiation Regulatory Agency 4814 South 40 Street
- Phoenix, Arizona 85040 Chairman Haricopa County Board of Supervisors 111 South Third Avenue Phoenix, Arizona 85003 Jack R.
- Newman, Esq.
Newman
& Holtzinger, P.C.
1615 L Street, N.W., Suite 1000 Washington, D.C.
20036 Curtis Hoskins Executive Vice President and Chief Operating Officer Palo Verde Services 2025 N. 3rd Street, Suite 220
- Phoenix, Arizona 85004 Roy P.
Lessey, Jr.,
Esq.
Bradley W. Jones, Esq.
Arkin, Gump, Strauss, Hauer and Feld El Paso Electric Company 1333 New Hampshire Ave., Suite 400 Washington, D.C.
20036
Enclosure ADDITIONAL QUESTIONS AND RECOMMENDED SENSITIVITY STUDIES BASED ON REVIEW OF PALO VERDE'S SUPPLEMENTAL RESPONSE TO GENERIC LETTER 88-20, SUPPLEMENT 4 BACKGROUND In December 1991, Arizona Public Service Company (APC) requested (Ref.
- 1) that the review level earthquake (RLE) for Palo Verde Nuclear Generating Station (PVNGS) be changed from 0.5g to 0.3g stating that, based on its own study, the seismic hazard for PVNGS can be shown to be consistent with the seismic hazards for 0.3g sites east of the Rocky Mountains.
The staff reviewed the
. information provided by APS and concluded that the information was not adequate to justify the reduction in RLE, and noted that further pursuit of this request would require a relatively 1argq number of additional studies in order to capture a range of opinions in the earth science community (Ref. 2).
APS has done additional seismic hazard analyses since December 1991 and submitted a supplemental seismic hazard analysis (Ref. 3) in August 1992 and requested additional review.
REVIEW OF SUPPLEMENTAL SEISMIC HAZARD ANALYSIS The NRC staff has reviewed these additional materials and concluded that they are not adequate to justify the reduction in RLE for Palo Verde site from 0.5g to 0.3g.
If APS wishes to pursue this request further, the NRC staff requests that APS address the following questions and perform additional seismic hazard sensitivity studies.
These will enable the staff to assess the validity of the arguments put forth by APS.
I.
questions 1.
What frequency ranges were used to evaluate ground motion and soil amplification (Ref. 3, Supplemental Report, p.ii, 1-3)?
It is stated that frequency content of ground motions in the western and eastern U.S.
is different.
2.
What is the reason for using DuBois et al.
as a default catalog (Ref. 3, Supplemental
- Report, p.4-1)?
Some of the other references are more recent.
3.
What indication is there that the Stokoe measurements at Treasure Island (the damping and modulus-reduction curves for the clay layers) are valid at Palo Verde (Ref. 3, Supplemental
- Report, p.5-11)?
4.
Should values other than logarithmic mean be considered (Ref. 3, Supplemental Report, p.5-15, 5-16)?
II.
Sensitivit Studies 1.
Seismic Zonation In the staff's review (Ref. 2) of the original probabilistic seismic hazard
- study, submitted by the licensee (Ref. I), the staff stated that the seismic zonation used in the hazard analysis was not considered to be adequate.
(The seismic source zones exclude higher seismicity to the southwest and northeast.)
The supplemental hazard analysis submitted by the licensee on August 4, 1992 (Ref. 3), did not consider any additional seismic zonation.
We have consulted studies published by the U.S. Geological Survey (USGS) and other investigators and we conclude that there are enough differences in expert opinion, with respect to the seismicity and zonation of the Palo Verde site region, to warrant additional sensitivity studies.
To ascertain the sensitivity of the seismic hazard to variations in seismic zonation and activity rates, we request that the licensee do an additional calculation using the zonation and activity rates specified in Table I and Figure I and include in this calculation the faults identified by the Geomatrix team together with their activity rates (Ref. 3, Supplemental
- Report, Table 4-2).
2.
Seismic Wave Attenuation The supplemental study incorporated ground motion models proposed by K.
Campbell and W. Joyner and D. Boore.
These models are inappropriate in the form presented because they were derived from southern California (deep soil) ground motion records and do not reflect the seismic attenuation expected in southern Arizona.
During a telephone conversation, Dr. Campbell said that he had recently revised his model and that of Joyner and Boore in an effort to simulate the southern Arizona geologic characteristics.
Dr. Campbell believes that the resulting modified Campbell and modified Joyner and Boore ground motion models are more appropriate for the Palo Verde site, assuming a soil depth to basement rock of 250 m.
Also the revised (supplemental) study utilizes the same ground motion model weighting scheme as the original study did.
The staff recommends that a sensitivity analysis be performed using the modified Campbell model, the modified Joyner and Boore model, and the HcGuire model with equal weights applied to all the models.
3.
Soil characteristics The supplemental study (Ref. 3) uses the modulus reduction and damping curves developed by Seed and Idriss and a "Standard Soil Profile."
The staff recommends that a sensitivity study be performed using the range of shear degradation models shown in Figure 2 and that it assesses the influence of using the upper range and lower range of the soil profiles shown in the supplemental report (Ref. 3, Supplemental
- Report, Figure 2-2).
4.
Comparison with Selected Sites in the Eastern United States In the original probabilistic seismic hazard study submitted by the licensee (Ref. I),
a comparison of the seismic hazard results with 'a selected site in the Eastern United States (Pilgrim) was provided (Ref. I, Sec. 6.1).
- However, this comparison was deleted in the Supplemental Report (Ref. 3).
It is important that such a comparison, to compare the seismic hazard results obtained for PVNGS to results obtained for sites in the Central and Eastern United States (CEUS),
be provided for staff review.
This comparison should use the results obtained from the above sensitivity studies which will enable
the staff to verify that the site seismic hazard, in terms of frequencies and amplitudes of interest, is indeed similar to that at sites in the CEUS.
REFERENCES 2.
3.
Letter from W. F.
Conway of Arizona Public Service Co. to NRC,
Subject:
Response
to Generic Letter 88-20, Suppl.
4, "Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities," dated December 26, 1991.
Letter from C. H. Thompson of NRC to W. F.
Conway of Arizona Public Service Co.,
Subject:
Review of Response to Generic Letter 88-20, Suppl.
4, "Individual Plant Examination of External Events - Palo Verde Nuclear Generating Station," dated June 17, 1992 Letter from W. F.
Conway of Arizona Public Service Co. to NRC,
Subject:
Supplemental
Response
to Generic Letter 88-20, Suppl.
4, "Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities, Pursuant to 10 CFR 50.54(f)," dated August 4, 1992
Enclosure 1
Table 1
Seismicity Parameters for the Palo Verde Site Recommended by NRC Type Zone Zone Zone No.
Source Z1 Zone 1 Z2 Zone 2 Z3 Zone 3 Range of Act. Rates
- 0.00854.01 6 0.7K' .110 0.031 0-0.0670 Range of b-values 0.67%.75 0.80-1.20 0.704.85 Range of Max. Mags.
5.0-5.5 6.5-8.0 5.5-6.0 Activityrates shown are annual rates of M> 5 for each source.
Z3 PALO VER S
E Z1 11BW 114W ~112W 110W Figure 1.
Seismic Source Zones (350 km radius) for the PALO VERDE Site recommended by NRC
2.0 X00 C) 0.8 0.6 SHEAR i%OUI.US RATIO fOR SANDS GENER IX 2%%
150' H
50' H
c 150Hc 50'.4 0.2 SEED-IORISS $70 IORISS 2000 0
30 DAMPING RATIO FOR SANDS 20 CJ IUJ a4J CA X%
10 SEED-IDRISS 70 IDRISS 90 OKO%TRIX }900 OcKc 50 50cHc 150 150cHc300 300cH 0.000 t 0.001 0.01
- 0. i 1.0 SINGLE RttPLITUOK SHERR STRAIN (N) 10 FIGURE 2. SHEAR DEGRADATIONMODELS FOR SANDS
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