ML20236P769
| ML20236P769 | |
| Person / Time | |
|---|---|
| Issue date: | 07/13/1987 |
| From: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | James Anderson ENERGY, DEPT. OF |
| References | |
| REF-WM-86 NUDOCS 8708130029 | |
| Download: ML20236P769 (5) | |
Text
gy yte LL-0B/MH/87/07/08/1-WM Record Fife WM Project FE N 1 h 1981 Docket No. /
909
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James R. Anderson, Project Manager Bl@u%_
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Uranium Mill Tailings Project _0ffice U.S. Department of Energy
' Albuquerque Operations Office Neh d io M '23dSF L
P.O. Box 5400
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. Albuquerque, NM 87115
Dear Mr. Anderson:
Enclosed are a few additional NRC staff comments on the Slick Rock draft Remedial Action Plan. These comments deal with seismology aspects of the design. We do not consider that comments 2, 3 and 4 will impact the design of the site. Mowever, we do not have the basis to confirm the conclusions that are being reached in the cited sections of the DRAP. -In addition, the technical approaches being used in the Slick Rock DRAP are likely being used at other' sites, which may affect the decision at these sites. Therefore, your consideration of these comments would definitely improve the quality of this and future RAP's.
If you have any questions regarding these commerts, please contact Mike Fliegel at (FTS) 427-4500.
Sincerely, S
Paul H. Lohaus, Acting Chief
.0perations Branch Division of Low-Level Waste Management and Decommissioning Office of Nuclear Material Safety and Safeguards
Enclosure:
Additional Slick Rock DEA /dRAP comments DISTRIBUTION:
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T SLICK ROCK, C0 DRAP COM4ENTS' UMTRA DOCUMENT REVIEW FORM SECTION 1 Site: Slick Rock, C0 Date: June 1987
' Document: DRAP Cormnentor: NRC Staff Geology / Seismology Coment:
1 Page: 0-112 Although Fault Group 1A includes mapped faults up to five km long within one km of the site area, the DRAP asserts that the faults are not capable.
Kirkham and Rogers (1981), however, consider the faults in this area to be potentially active Neogene faults. Use of Bonilla's equation as shown on Page D-104 of this DRAP results in a maximum earthquake magnitude of 6.5 at the site for a 5 km-long fault. The 84th percentile Campbell (1981) acceleration for a magnitude 6.5 earthquake would be 0.79, which is much. higher than the 0.21g used for design purposes at Slick Rock. The RAP should be revised to demonstrate that faults in Group 1A are not capable Neogene faults or to reassess the design seismic acceleration.
References:
Kirkham, R.M., and W.P. Rogers,1981, Earthquake Potential in Colorado, a Preliminary Evaluation, Colorado Geological Survey, Bulletin No. 43.
Campbell, K. W. 1981.
"Near-Source Attenuation of Peak Horizontal Acceleration," Bulletin of the Seismological Society of America, Vol. 71, pp. 2039-2070.
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l SLICK ROCK, C0 DRAP COMMENTS 2-UMTRA DOCUMENT REVIEW FORM q
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Site: Slick Rock, C0 Date: June 1987 Document: DRAP Commentor: NRC Staff Geology / Seismology Comment:
2 Page: D-102 This page states in paragraph 3 that "...the probability of occurrence of a magnitudeg.5eventwithinanynine-mile (15-km)radiuswithintheregionis 0.06 x 10~. The recurrence interval of an ME earthquake within any nine-mile (15-km) radius is thus 166,700 years." The bases for the calculated earthquake probability and recurrence interval are not clearly stated and cannot be verified by NRC staff based on the infonnation given. Calculation of earthquake recurrence interval is important with respect to selecting the seismologic design basis for the stabilized tailings embankment. The RAP should be revised to provide the detailed calculations used to determine the recurrence of the ME earthquake for the Slick Rock area.
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i SLICK ROCK, C0 DRAP COMMENTS
-3 UMTRA DOCUMENT REVIEW FORM
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1 SECTION 1 Site: Slick Rock, C0 Date: June 1987 Document: DRAP Commentor: NRC Staff Geology / Seismology Comment:
3 Page:
D-104 This page indicates that the threshold magnitude that would result in the propagation of a fault rupture to the earth's surface in a tectonic pinte interior can be determined by setting fault rupture length equal to zer i in the Bonilla, et al., equation and solving for the magnitude. Such a process is in error mathematically because the equation requires taking the log of the fault rupture length and taking the log of zero is a undefined number. The process is also in error because the assumption of a zero, or very small, surface rupture length is an insupportable extrapolation of the Bonilla, et al., data. The RAP should be revised to justify the assumption of a zero, or very small, surface rupture length and to demonstrate that this assumption provides conservative estimates of the potential for surface rupture of a fault in the Slick Rock area.
Reference:
Bonilla et al. (M. G. Bonilla, R. K. Mark, and J. J. Lienkaemper),1984,
" Statistical Relations Among Earthquake Magnitude, Surface Rupture Length and Surface Fault Displacement," Bulletin _of the Seismological Society of America, Vol. 74. No. 6, pp. 2379-2411.
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SLICK ROCK, C0 DRAP COMMENTS _.,
UMTRA DOCUMENT REVIEW FORM i
SECTION 1 Site: Slick _ Rock, C0 Date: June 1987 Document: DRAP l
Cormentor: NRC Staff Geology / Seismology Comment:
4 Page: D-104 This page makes the following statement: "The probability of occurrence of the FE'(FloatingEarthquake)withinthening-mile (15km)radiusofanysiteduring probability figure (2.25 x 10~3)5 x 10
, or less than one percent." appears to be off by a facto the 1000-year design life is 2 2 This The RAP should be revised to correct the FE probability during the 1000-year
- design life of the tailings embankment and to describe the calculations used to estimate this probability.
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