9.5.1 Example Sodium Fast Reactor (ESFR) case study

The PR&PP methodology was developed and tested with the help of an example design. This was the Example Sodium Fast Reactor (ESFR). The design is described in detail in GenIV International Forum (2011a) and consists of four 300 MWe sodium reactors and associated fuel-processing facilities. It is based on the integral fast reactor design that was in development in the 1990s. While this section of the SMR Handbook is focused on iPWRs, the lessons learned from the use of the PR&PP methodology on other reactor concepts are sufficiently generic that they can mostly apply to iPWRs as well. The basic element in common is that the analysis would be performed on a novel reactor concept that is still in the design phase.

Basic lessons learned from the Case Study GenIV International Forum (2011a) included the following:

• Each PR&PP evaluation should start with a qualitative analysis allowing scoping of the assumed threats and identification of targets, system elements, etc.

• Detailed guidance for qualitative analyses should be included in the methodology.

• Access to proper technical expertise on the system design as well as on safeguards and physical protection measures is essential for a PR&PP evaluation.

• The use of formal expert elicitation techniques can ensure accountability and traceability of the results and consistency in the analysis.

• Qualitative analysis offers valuable results, even at the preliminary design level.

• Greater standardization of the methodology and its use is needed.

In addition, during the evaluation process the analyst must frequently introduce assumptions about details of the system design which are not yet available at early design stages: for example, the delay time that a door or portal might generate for a PP adversary. As the study progressed, the PR&PP working group realized that when these assumptions are documented, they can provide the basis for establishing functional requirements and design bases documentation for a system at the conceptual design stage. By documenting these assumptions as design bases information, the detailed design of the SMR can be assured of producing a design that is consistent with the PR&PP performance predicted in the initial conceptual design evaluation (or, if the assumptions cannot be realized in detailed design, the original PR&PP evaluations must be modified appropriately).