Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

382 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 K E Y W O R D S safety analysis, post-glacial faulting, seismicity, spent fuel repository (1) Swedish Radiation Safety Authority, 17116 Stockholm, Sweden, Pettersson *Email: Carl-Henrik.Pettersson@ssm.se Carl-Henrik Pettersson (1) LICENSE REVIEW OF A SPENT FUEL REPOSITORY – ASSESSMENT OF LONG-TERM SEISMIC STABILITY A B S T R A C T As part of the licensing process for a spent nuclear fuel repository the Swedish Radiation Safety Authority (SSM) has reviewed the long-term safety analysis of the KBS-3 repository system proposed by the Swedish Nuclear Fuel and Waste Management Co. (SKB). Assessment of the past, present and future seismicity for the candidate site for a disposal facility for spent nuclear fuel is an integral part of the safety analysis. The spatial and temporal variations of the seismic activity in Sweden have been an ongoing debate since the discovery of glacially- induced faulting that occurred during the deglaciation of the Weichselian ice sheet. And for the last three decades, several claims have been made that the sedimentary stratigraphy recording the deglacial history shows an abundance of seismic events of considerable magnitudes. SSM’s review needs to address these claims, as well as SKB’s assessment of present and future seismicity. The objective of this paper is to describe the planning and execution of SSM’s review of the candidate site long term stability in order to discuss lessons learnt that can be applied to the review of other safety cases for a sensitive facility such as a spent nuclear fuel repository. I N T R O D U C T I O N In 2018, the Swedish Radiation Safety Authority (SSM) published its review (SSM 2018:07) of the Swedish Nuclear Fuel and Waste Management Company (SKB) license application for construction and operation of a spent nuclear fuel repository at Forsmark close to the Baltic coast of central Sweden (figure 1). The license application is based on the KBS- 3 concept that isolates the spent nuclear fuel by encapsulating it in copper canisters surrounded by bentonite clay in deposition holes drilled from tunnels at 450 m below ground in granitic rock (SKB, 2011). One important external event that can affect the repository systems ability to contain and isolate the spent nuclear fuel from the biosphere is mechanical failure