ML20141P097
| ML20141P097 | |
| Person / Time | |
|---|---|
| Issue date: | 02/18/1986 |
| From: | Knapp M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Higginbotham L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-58 NUDOCS 8603180554 | |
| Download: ML20141P097 (4) | |
Text
.
WM Record File WM Project 5f' DISTRIBUTION us us Docket No-WMGT r/f EHawkins,URFq j
NMSS r/f MHaisfield FEB 181986 REBrwning BJagnnath WM.,'", "- ~"m' c "o' Distribution-j MBell DGillen
~
~f
___ J0 Bunting JGreeves
-- d-MRKnapp MBlackford
((ejup b WI.1,6pSS)_
JValdes & r/f M
MEMORANDUM FOR:
Leo Higginbotham, Chief WMLU FROM:
Malcolm R. Knapp, Chief WMGT
SUBJECT:
REVIEW 0F " SUPPLEMENTAL SEISMIC STUDIES PERFORMED IN SUPPORT OF THE REMEDIAL ACTION PLAN AT THE SHIPROCK TAILINGS SITE," TAR # WM_86002.
The Geotechnical Branch has completed its review of the subiect document. The review was coordinated by Jose Valdes (geology) with input from Michael Blackford (seismology).
The conclusion of the DOE document reviewed is that:
"It is... recommended that the seismic design parameters employed during pile design not be modified or reevaluated at this time." Whereas the validity of this conclusion ultimately depends on engineering considerations, our review of the geotechnical aspects of the issue leads us to conclude that the proposed maximum credible earthquake of magnitude 5.7 for the Shiprock site is not justified and therefore not acceptable. Our reasons for this conclusion are the following:
- 1) Table 1 of Algermissen et al. (1982) indicates that the maximum magnitude for the Colorado Plateau (Algermissen's source zone no. 16) should be 6.1.
Using Algermissen's relationship for magnitude as a function of intensity, M =
1.3 + 0.6I, a magnitude 6.1 would be the equivalent of Modified Mercalli Intensity 8fI = 8.
This is near or slightly above the maximum intensity observedwithi8theColoradoPlateauduringitsbriefhistoricalperiod.
It would not be overly conservative to assume a somewhat higher magnitude value since the period of performance is significantly longer than the historical period.
- 2) In its assessment of the seismic hazard of two potential sites for the disposal of high-level radioactive waste in the Paradox Basin of the Colorado Plateau, the DOE (1984) identified structures capable of generatinq earthquakes with magnitudes as high as 6.5.
The presence of such structures within the plateau, and the fact that surface ruptures or other geomorphic manifestations of earthquakes in the 6.0 to 6.5 magnitude range may be muted by a few decades to a few centuries of erosion, gives rise to the possibility that such an earthquake may have occurred despite the lack of any existing structural deformations.
8603180554 860210 PDR WASTE WM-58 PDR
)FC :WMGT
- WMGT
- WMGT
- WMGT 4AME :JValdes;mt :M81ackford
- PSJustus
- MRKnapp
) ATE :86/02/
- 86/02/
- 86/02/
- 86/02/
4 I
l l
WM-58/JV/2/11/86/SHP
-2 l
l
- 3) Preliminary estimates of the MCE by the DOE / TAC for other uranium mill tailings sites in in the vicinity of the Shiprock site are given as 6.2 (R.
l Weeks of Sergent, Hauskins & Beckwith, 1986, personal communication).
l l
Based on the above information, we consider that a value of 6.2 for the magnitude of the maximum credible earthquake for the Shiprock site is justified and would be reasonable and acceptable, i
'The peak horizontal acceleration resulting at the site from a 6.2 magnitude eartnquake occurring at a distance of 15 km is 0.21 g (using Campbell, 1981, 84th percentile values in accordance to criteria in NRC's UMTRAP Standard Review Plan).
Engineering considerations would determine how the seismic coefficient derived from this number compares with the present 0.13 g design j
acceleration for the pile.
It should be noted that the DOE document endorses the use of mean maximum acceleration values in rock derivei from Schnable and Seed (1973) but does not provide a adequate rationale for the doption of a mean maximum acceleration value of 0.13 g as for the Shiprock site.
Figure 5 of. Schnable and Seed (1973) indicates that an earthquake of magnitude i 7 yields a mean maximum acceleration value in rock of 0.13 g at a ofstance of approximately 25 kilometers. The DOE document does not just fy why this distance was chosen to l
detcrmine the acceleration for the site. A: 15 kilometers, which is the l
site-to-source distance recommended by NRC in the UMTRAP SRP for " floating earthquakes," the mean value for the acce'eration from Schnable and Seed would be about 0.21 g.
i In regard to the characterization of geologic structures in the region of the site, we find that, although the investigations undertaken precede the L
formulation of NRC's UMTRAP SRP and DOE's Technical Approach Document (TAD),
DOE's studies are commensurate with the criteria stipulated in the SRP and are therefore' acceptable. We would like to note, however, that the information in the Supplemental Seismic Studies document itself was inadequate to enable us to reach this determination as it lacks supporting documentation on the details l
and scope of the investigations undertaken. Our findings, therefore, rely on additional information supplied by the DOE / TAC during the course of the review.
l This information, now on file in the Document Control Center, consists of the l
following:
a) Comprehensive NOAA Earthquake Data File for the Colorado Plateau.
b) Province boundary map.
e l'
l l
DFC :WMGT
- WMGT
- WMGT
- WMGT
$ME:JValdes;mt :MBlackford :PSJustus
- MRKnapp
[ ATE:86/02/
- 86/02/
- 86/02/
- 86/02/
I
WM-58/JV/2/11/86/SHP c) Notes and discussion of the observations made during aerial reconnaissance, field investigations, and photogeologic interpretations.
d) Clarification of the numbered references associated with fault listings, e) Clarification of the specifications of the Landsat imagery used for photointerpretation (multispectral scanner, band 4).
In regard to item (a) specifically, it should be emphasized that NRC reviewers need to have reasonable assurance that the scope and nature of the investigations undertaken by DOE are adequate to support a particular finding.
Supporting information is particularly important when negative conclusions are presented regarding the presence of capable faults in the region of investigation. To this end, detailed notes of the field observations made (from aerial or ground reconnaissance, photogeologic interpretations, etc.)
with dates, names of the investigators, locations examined, geologic descriptions of formations present, etc., should be compiled. The notes should be written so as to be interpretable by other geologists.
Selected field notes and other supporting information that DOE considers important and illustrative should accompany the primary document sent to NRC for review. Additional supporting information should be retained and made available to NRC on request.
In the future, NRC reviews of UMTRAP documents could be expedited and facilitated if the types of information deficiencies encountered in this review were remedied.
As a final comment, in regard to item (e), we would like to note that the use of Landsat multispectral scanner (MSS) bands 6 and 7, rather than hand 4, is considered preferable for obtaining structural geologic information (Carter, 1976).
It is recommended that DOE use MSS band 6 or 7 imagery in performing geologic characterization at other UMTRAP sites.
If you have any questions regarding our review, please contact Philip Justus.
S/
Malcolm R. Knapp, Chief Geotechnical Branch Division of Waste Management, NMSS l
)FC :WMGT
- WMGT
- WMGT
- WMGT WAME :JValdes;mt :MBlackford :PSJustus
- MRKnapp MTE :86/02/
- 86/02/
- 86/02/
- 86/02/
WM-58/JV/2/11/86/SHP REFERENCES CITED Algermissen, S.T., D.M. Perkins, P.C. Thenhaus, S.L. Hanson, and B.L. Bender, 1982, "Probabilistic Estimates of Maximum Acceleration and Velocity of Rock in the Contiguous United States," U.S. Geological Survey Open-File Report 82 1033, Washington, D.C.
Campbell, K.W.,1981, "Near-Source Attenuation of Peak Horizontal Acceleration," Bulletin of the Seismological Society of America, vol. 71,
- p. 2039-2070.
Carter, W.D., 1976, " Structural Geology and Mineral-Resources Inventory of the Andes Mountains, South America," in Williams, R.S., Jr. and W.D. Carter (eds.) "ERTS-1, A New Window on Oiir Planet," U.S. Geological Survey Professional Paper 929, p. 92-98.
Schabel, P. and H.B. Seed, 1973, " Accelerations in Rocks for Earthquakes in the Western United States," Seismological Society of America Bulletin, vol. 63, p. 501-516.
U.S. Department of Energy,1984, " Draft Environmental Assessment-Davis Canyon Site, Utah (D0E/RW-0010)," Washington, D.C., p. 6-108.
>____:...........:.....%...___.::W.MG'
)FC :WMGT
- WMGT
- WMGT
__I IAME :JValdes;mt :MBlackford :PSJ 1
- MRKnapp
.....:....__...__:..._____....:_..... y......:....__......:......__.....________...:.__________
) ATE :86/02/lf
- 86/02/lg
- 86/02/l/
- 86/02/l7