The 23 August 2011 M w (moment magnitude) 5.7 ± 0.1, Mineral, Virginia, earthquake was the largest and most damaging in the central and eastern United States since the 1886 M w 6.8–7.0, Charleston, South Carolina, earthquake. Seismic data indicate that the earthquake rupture occurred on a southeast-dipping reverse fault and consisted of three subevents that progressed northeastward and updip. U.S. Geological Survey (USGS) “Did You Feel It?” intensity reports from across the eastern United States and southeastern Canada, rockfalls triggered at distances to 245 km, and regional groundwater-level changes are all consistent with efficient propagation of high-frequency seismic waves (~1 Hz and higher) in eastern North America due to low attenuation. Reported damage included cracked or shifted foundations and broken walls or chimneys, notably in unreinforced masonry, and indicated intensities up to VIII in the epicentral area based on USGS “Did You Feel It?” reports. The earthquake triggered the first automatic shutdown of a U.S. nuclear power plant, located ~23 km northeast of the main shock epicenter. Although shaking exceeded the plant’s design basis earthquake, the actual damage to safety-related structures, systems, and components was superficial. Damage to relatively tall masonry structures 130 km to the northeast in Washington, D.C., was consistent with source directivity, soft-soil ground-motion amplification, and anisotropic wave propagation with lower attenuation parallel to the northeast-trending Appalachian tectonic fabric. The earthquake and aftershocks occurred in crystalline rocks within Paleozoic thrust sheets of the Chopawamsic terrane. The main shock and majority of aftershocks delineated the newly named Quail fault zone in the subsurface, and shallow aftershocks defined outlying faults. The earthquake induced minor liquefaction sand boils, but notably there was no evidence of a surface fault rupture. Recurrence intervals, and evidence for larger earthquakes in the Quaternary in this area, remain important unknowns. This event, along with similar events during historical time, is a reminder that earthquakes of similar or larger magnitude pose a real hazard in eastern North America.

The 2011 Mineral, Virginia, earthquake is one of the larger recorded seismic events occurring east of the Rocky Mountains since seismic instrumentation was first deployed. The operation of the North Anna nuclear power station (NANPS), located ~22 km northeast of the epicenter, was affected by the earthquake vibration. This moderate event caused the first incident in which a commercial U.S. nuclear power plant experienced a safe shutdown as a result of earthquake ground motion. Post-earthquake investigations confirmed that important safety-related structures, systems, and components (SSCs) at the NANPS did not have any detectable damage. Damage at the NANPS consisted of cracking and spalling of some of the non-safety-related ancillary structures, and the plant was restarted after three months of intensive inspections and reviews. Response spectra developed from the recorded ground motion at the NANPS showed a modest exceedance of the plant seismic design levels for safety-related SSCs, but these SSCs were not damaged and maintained their functionality. The NANPS performance, in combination with other global examples, shows that nuclear power plants have been able to function safely even when earthquake ground motions exceeded the design levels of the SSCs. In this paper we describe the observed earthquake effects at the NANPS and discuss the original geologic and seismic characterization of the plant site. We also discuss the impacts of other earthquakes on the performance of various nuclear power plants, and previous and current seismic hazard and risk evaluations for U.S. nuclear power plants.

Abstract The Finnish power companies TVO and FPH currently operate four nuclear reactors, two each at the Olkiluoto and Loviisa sites. Both companies are responsible for the safe management of nuclear wastes. The underground repository program for low- and intermediate-level waste was commissioned in the late 1970s. From the start, the design basis has been geological disposal, the safety of which rests on natural and engineered barriers. The disposal system should isolate the waste for a few hundred years. During this time, the radiotoxicity of the waste will decline significantly. The critical radionuclides are 14 C, 239 Pu/ 240 Pu, 59 Ni, 90 Sr, and 137 Cs. The Olkiluoto site consists mainly of micaceous gneiss intercalated with sparsely fractured tonalite. A tonalitic portion of the site was chosen for more detailed characterization. The Loviisa site consists entirely of Rapakivi granite, which is coarse grained and porphyritic. The repository layout was in both cases constrained by the local geology. At Olkiluoto, the shape of the tonalitic body bounded by fracture zones led to a vertical silo-type concept 60–100 m below the surface. At Loviisa, the subhorizontal fracture zones above the planned disposal depth favored horizontal drifts 120 m below the surface. Thorough safety assessments were conducted during the licensing process. The Olkiluoto repository was built between 1988 and 1992, and the Loviisa repository was built between 1993 and 1997. Operation of Olkiluoto was commissioned in 1992, and Loviisa was commissioned in 1998. In the future, the repositories will also be used for disposal of waste when the nuclear power plants are decommissioned.

Abstract Geological disposal has been the basis for the Swedish program for disposal of radioactive waste since its beginning in the mid-1970s. Two underground facilities have been in operation since the late 1980s. The construction of the final repository for short-lived, low- and intermediate-level waste, SFR (Swedish final repository for radioactive operational waste), started in 1983, and it was put into operation in 1988. The facility is located 50 m below the sea, close to the Forsmark nuclear power plant, where the sea has a depth of ∼5 m. Low-level waste is placed in four rock vaults, each of which has a length of 160 m. Intermediate-level waste is stored in a concrete silo that has a height of 50 m and an inner diameter of 26 m. The disposal vaults are connected to the surface by two parallel access tunnels. The total disposal capacity is 63,000 m 3 , of which about one-half is currently in use. An expansion of the SFR is planned to accommodate radioactive waste from the decommissioning of the nation's power plants. Construction of the interim storage facility for spent nuclear fuel, Clab, started in 1980, and the facility was put into operation in 1985. The facility is located at the Oskarshamn nuclear power plant. The fuel assemblies are stored in water pools located in two 120-m-long rock chambers. The roof of the rock chambers is ∼30 m below the ground surface. Construction of a second storage vault has recently been completed. The Äspö Hard Rock Laboratory is an underground facility for developing and testing characterization methods and the different components of a system for deep geological disposal under realistic repository conditions. The facility reaches a depth of 460 m below the surface. After 5 yr of construction, it was put into operation in 1995. The licensing, construction, and operation of these facilities have provided valuable experience that is being used for the site characterization and design work currently in progress for the deep geological repository for spent nuclear fuel. The spent nuclear fuel will be disposed of in a repository located at depths between 400 and 700 m. The disposal concept is based on isolation of the spent fuel in copper canisters surrounded by a buffer of highly compacted bentonite placed in a borehole in granitic rock. Site investigations are currently in progress at two potential sites. This project is a major geoscientific undertaking that is planned to be completed in 2009 with the selection of one of the sites for the deep repository.