Impact of seismicity on the stability of an underground repository

Conference · Wed Dec 01 04:00:00 EST 1982

OSTI ID:6612344

Rasmussen, N H; Rohay, A C

The effects of seismicity on an underground nuclear-waste repository are different from those normally associated with a surface nuclear facility. Vibratory damage to underground openings appears to result from peak ground velocities in excess of 25 to 100 cm/sec, depending on rock type and support structures. Although vibratory loading may be an important design consideration for the operational life of a repository (less than or equal to 100 years), rupture of the host rock or shaft seals is the primary concern for the period of postclosure repository performance assessment (approx. 10,000 years). The possible impact of seismic events on an underground repository is illustrated by means of a graph constructed using relationships between peak ground velocity, earthquake magnitude, and hypocentral distance. The possibility of a fault rupturing a repository is modeled using Brune's circular fault model and superimposed on the graph. The vibratory-damage thresholds are not exceeded unless the seismic event is sufficiently close that fault intersection of the repository is possible. Although these cases correspond to relatively large fault radii, the fault displacements are less than 1 cm and the average stress drops are of the order of one bar. At hypocentral distances approximately equal to the fault radii, the peak ground velocities imply peak shear stresses that are comparable to the stress drops of the earthquakes (1 to 100 bars), consistent with the Brune model. Recurrence curves are considered in conjunction with the random probability of earthquake occurrence within specific hemispherical volumes in order to determine the annual probability of occurrence of various magnitude earthquakes within the volume. For b-values of 1.25, the possibility of exceeding the damage threshold is enarly independent of magnitude.

• Research Organization: Rockwell International Corp., Richland, WA (USA). Energy Systems Group
• DOE Contract Number: AC06-77RL01030
• OSTI ID: 6612344
• Report Number(s): RHO-BW-SA-269-P; CONF-821221-1; ON: DE83004676
• Country of Publication: United States
• Language: English

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