ML20138B092
| ML20138B092 | |
| Person / Time | |
|---|---|
| Issue date: | 11/21/1985 |
| From: | Jagannath B NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Rager R JACOBS ENGINEERING GROUP, INC. |
| References | |
| REF-WM-39 NUDOCS 8512120206 | |
| Download: ML20138B092 (6) | |
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//m.37 NOV 21125 MBe11 30/11/ZG/55 JGreeves MTokar BJagannath MNataraja Palackford Ron Rager, Geotechnical Manager JValdes Jacobs Engineering Group, Inc.
PJustus 5301 Central Avenue, Suite 1700 HMiller Albuquerque, NM 87108 MXnapp LHigginbotham
Dear Ron,
SWastler w/ encl.
In accordance with your request of October 18, 1985, the final draft of the seismic studies portion of the DOE's UMTRA Design Manual has been reviewed by the NRC team members of the Technical Discussion Group II. Review comments and a marked copy are attached to this memo.
Please call any of the NRC members of the team if you would like to discuss our review coments.
Sincerely, Banad Jagannath, Project Manager Engineering Branch Division of Waste Management, NMSS
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1 NRC REVIEW COMMENTS ON SEISMIC STUDIES SECTION OF DOE'S UMTRAP DESIGN MANUAL Section 1.0, Page 1, Paragraph 1 It is stated that geologic studies provide an initial set of earthquake design parareters that includes "an on-site peak horizontal ground accelera', ion value." It should be stated clearly that this acceleration is considered to be the nonamplified peak horizontal acceleration described in section 2, p. 2.
Section 2, Page 3, Bullet 5 Within the context of the definition of " acceleration," the qualifier " design" is not explained. An explanation of the relation of design acceleration to the design earthquake would be appropriate here.
Section 3.0, Page 5, Bullet 1 It is stated that the pertinent data to be acquired and interpreted to define seismotectonic hazards at a site "...will include existing maps which delineate capable faults and bedrock faults of any age..." As " capable fault" and
" bedrock fault" are not mutually exclusive terms, the meaning and intent of this statement could be made clearer by replacing " capable faults and bedrock faults" with the term " faults."
Section 3.0, Page 5, Bullet 3.
It is stated that a 200 kilometer radius was selected as the radius for investigations of seismicity so that any seismic event which could have caused detectable on-site ground motion will be included in the compiled record.
Since seismic events more distant than 200 kilometers from the site can cause detectable on-site ground motion, it is suggested that this statement be clarified by including some minimum threshold ground motion for events beyond 200 kilometers so as to limit the compilation to earthquakes that can significantly affect the site.
It is also stated in this bullet-item that "all earthquake data files, epicentral listings from ctate-maintained seismic nets, and available microseismic data will be obtained and evaluated." The term " state-maintained" is unclear, or at least limiting, in the consideration of available seismic j
2 data. A more general phrase (such as: "To the extent practicable, all federal and state, as well as privately or commercially available earthquake data bases
...") could be used to describe those data bases expected to be obtained and evaluated. Also, care should be taken in using the term " microseismic" so that there will be no confusion as to whether the user is referring to microearthquakes or microseisms.
Section 3.0, Page 6, Bullet 4.
It is stated that the seismic records for provinces within 200 km of the site will be analyzed "and the maximum recorded earthquake for each province will be identified." We would like to emphasize that it is the maximum recorded earthquake not associated with a known tectonic structure that is of concern in determining the largest floating earthquake for a given province.
It is also stated in this bullet-item that:
"For outlying provinces, the credible earthquake will also be identified." The meaning of the term
" credible earthquake" needs to be stated.
Section 3.0, Page 6, Bullet 5.
It is stated that, in plottina all photogeologic lineaments or geomorphic features indicative of an active seismic setting, " specific attention will be paid to actlye fault or bedrock fault traces identified by previous investigators." As " active fault" (which has various meanings) and " bedrock fault" are not mutually exclusive terms, the intent and meaning of this statement could be made clearer by replacing " active fault or bedrock fault traces" with simply " fault traces."
Section'3.0, Pages 6-7, Bullet 6.
In this and other parts of the document the term "ticating earthquake" is used rather ambiguously and inconsistently.
In referring to the maximum floating earthquake within a given
)rovince, it would be advisable to use the term
" largest floating earthquace." The term " controlling floating earthquake" (as used in section 3, page 7, bullet 7) should be consistently and explicitly used in referring to that floating earthquake which, from amongst all-the largest floating earthqua'<es for different provinces, yields the largest on-site peak horizontal ground acceleration. Explicit use of these terms, rather than merely
" floating earthquake," would help clarify ambiguities in meaning.
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3 It is stated, with regard to determining "the magnitude of the [ largest]
floating earthquake within each province," that its magnitude "will not be less than the largest event not associated with a known structure." Thus, as i
suggested by NRC at the September 27th Group II meeting, the term " largest recorded event" has been changed to' read " largest event." NRC would like to further elaborate on its rationale for suggesting this change.
Specifying the use of " recorded" earthquakes would exclude from consideration any paleoseismological data that may indicate prehistoric seismic activity, of inferable intensity, not associated with an established tectonic structure.
Obermeir and others -(1985), for example, have found that late Quaternary sand 4
blows in the area of Charleston, South Carolina, indicate at least two prehistoric earthquakes with shaking severities comparable to the recorded 1886 event. To the extent that they may be available or reasonably obtainable, paleoseismological data may thus permit the extension of the existing seismic record and allow for a more accurate determination of the magnitude of the largest floating earthquake in a given province.
Section 3, Page 7, Bullet 7.
It can be implied from this bullet-item that the " design acceleration" is necessarily equivalent to that associated with the controlling floating earthquake. This implication arises from the statements that:
"All fault 4
systems which could be [not?] produce accelerations in excess of the
[ controlling] floating earthquake value will be further analyzed. Any faults which appear capable of producing the design acceleration will be subject to the actions discussed...."
In order to avoid this implication, the phrase " accelerations in excess of the
[ controlling] floating earthquake value," should simply be repeated in the last sentence in place of "the design acceleration."
Section 3.0, Pages 7-8, Bullet 8.
It is stated in regard to fault studies that:
"For the critical faults, suitable geomorphic techniques will be applied to determine whether they are capable." NCR reconnends that the term " critical faults" be eliminated from i
this and other statements in the text. Though it is apparent, within the context of the document, that the term refers to faults that may cause accelerations at the site equal to or greater than that produced by the controlling floating earthquake, confusion or misuse may arise if the term is
- used out of context.
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4 Section 4.1, Page 9, last paragraph.
Reference to potential hazard of earthquake induced damage may be interpreted as requiring a detailed hazard / risk evaluation prior to deciding on the method of estimating the attenuation / amplification of the acceleration at the site.
Revise the paragraph, as suggested below, to avoid reference to the hazard / risk analysis:
" Adjustment for attenuation / amplification of acceleration through the soil may be estimated using curves developed by Seed and Idriss (1982).
If the factor of safety is less than 1.0, then a detailed site amplification analysis may be warranted to estimate the surface acceleration used in the seismic design."
5 REFERENCE CITED Obermeier, S.F., G.S. Gregory, R.E. Weems, R.L. Gelinas and M. Rubin, 1985,
" Geologic Evidence for Recurrent Moderate to Large Earthquakes Near Charleston, South Carolina," Science, vol. 227, p. 408-411.
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