Safety

The most important factor in final disposal of spent nuclear fuel is the safety of the solution. Final disposal must not pose a threat to people or environment.

 

Only Safe Final Disposal Is Feasible

Long-term safety of the solution is essential when it comes to final disposal of spent nuclear fuel. Long-term safety refers to the safety of final disposal after the operation of the final disposal facility has been terminated and the repository has been closed.

 

Safety is ensured by relentless research and development work. Research helps in determining if the conditions inside the bedrock are suitable for final disposal and in estimating the impact of final disposal on safety. The principal purpose in development work is to ensure that the canister and the sealing seam of the cover will last for the required time and that the bentonite and the filling material will function as expected.

 

The safety of final disposal is also assessed during the various stages of the licensing procedure. At the stage when the decision-in-principle is being made, the Radiation and Nuclear Safety Authority conducts a preliminary safety assessment. Later, at the construction licence stage, the Radiation and Nuclear Safety Authority assesses the safety of the planned final disposal facility and repository; and at the operating licence phase it assesses the safety of the constructed final disposal facility. Only a final disposal solution declared safe by the Radiation and Nuclear Safety Authority can proceed through the licensing procedure.

 

Multiple Barriers Prevent the Release of Any Radioactive Substance to the Biotic Environment

Long-term safety is based on the multiple barriers principle. Radioactive substances are contained in several barriers that support each other, yet are as independent from each other as possible, so that the failure of one barrier will not endanger the overall functioning of the isolation. These barriers include the ceramic state of the fuel, the canister made of copper and cast iron, the barrier bentonite, the tunnel filling material, and the bedrock.

 

The Safety Case Demonstrates the Safety Even During Sequences of Unlikely Events

The suitability of the Olkiluoto bedrock for the final disposal and the functioning of the technical solution is demonstrated with a so-called safety case. The safety case consists of a group of separate reports presenting the starting points of the safety assessment, the models and initial data used, the assessment methods, the assessment results, and related insecurities and conclusions of the safety inspections and their reliability. The safety case will be enclosed with the construction licence application to be submitted in 2012.