Given the increasing evidence that fracking is a cause of earthquakes and given the continuing problems associated with Fukushima nuclear facilities in Japan directly related to earthquakes, and given the great public concern throughout Europe after the Chernobyl disaster:
Following the unexpected seismic tremors at the first shale gas well in the UK, at Preese Hall near Blackpool in 2011, the Department of Energy & Climate Change (DECC) suspended all fracking operations for shale gas pending an investigation of the causes of these tremors and the scope for mitigation of seismic risks in any future operations of this type.
Following a thorough review, in December 2012 DECC announced new controls to mitigate the risks of undesirable seismic activity (Ref 1). Under these controls, operators are required to review the available information on faults in the area and to monitor background seismicity before operations commence. Once fracking commences, real time seismic monitoring is to be used to operate a traffic-light warning protocol under which operations will be halted and pressures immediately reduced should a seismic event greater than a pre-defined threshold be detected. This threshold is set well below the level of vibration that could be felt at the surface by an individual. The protocol would then enable a review of the possible causes of the event and allow further steps to be taken to prevent the occurrence of larger events. Further details about fracking, including induced seismicity, can be found at Ref 2.
Modern UK nuclear facilities are designed to be resilient to earthquakes up to a severity that would only be exceeded once in 10,000 years. Older facilities have been assessed against this standard and modified where necessary to ensure that any consequences are within acceptable limits. Earth tremors associated with fracking processes under the controls outlined above are much smaller than this and are therefore not of concern for nuclear facilities.
Licensees are required to consider the effect of nearby industrial facilities and demonstrate that any associated risks to the nuclear facility are included within the nuclear facility risk assessment (safety case). This includes risks from fracking activities. Any such risk assessment takes into account the distance of the operations from the site on a case-by-case basis and hence there are no pre-prescribed distance limits associated with UK nuclear sites and stores for fracking or any other activity. Licensees are required to maintain a watching brief on activities outside of their control to ensure that any new or changed activity is enveloped by their safety case.