Current NRC regulations were developed based on traditional large NPP LWR designs. Current requirements related to the human role in the plant deal primarily with avoiding human error and improving human reliability in normal and abnormal operational conditions. This includes requirements for control room staffing, criteria for evaluation of HSIs, and conducting HFE activities in the power plant. Some provision is currently made for new designs, for example for minimum staffing of the NPP, as described in the Code of Federal Regulations, 10 CFR 50.54. However, most new reactor designs, and particularly SMR designs, differ substantially from traditional designs in a number of aspects, including size and number of reactors, inherent passive safety systems, fuel type and coolant type. These differences present unique issues in terms of licensing and regulation.

Although current NRC guidance provides a general framework for conducting design-specific reviews, the review of control room and HSI designs as well as staffing plans and potential exemption requests is expected to be challenging for SMR designs. This is because of the differences between the new reactor designs and previously licensed reactor designs and also because of a lack of research and design data to provide an adequate technical basis for decisions. Initial evaluation conducted by the NRC has identified a number of differences between SMR and other advanced reactor design and operating philosophies and the designs for larger reactors currently licensed or being evaluated for licensing. These differences include the following:

• SMRs may require different operator tasks. The task requirements will include operating multiple units in different modes of operation. A major challenge will be to identify tasks that may be omitted and those that could substantially affect operator workload.

• Very limited operational experience will be available to use as a resource, especially if these designs are FOAK. The use and observation of simulator activities will be important to verify the task analyses and staffing plans. Parallels in other industries may be useful, if they exist.

• Integration challenges exist in defining not only tasks required for operating the unit, but also for interacting with other on-site maintenance and support organisations for multiple units.

• The skill set for control room operators, especially those required to manage more than one product, may require a different distribution of qualifications (e. g. more senior reactor operators fewer reactor operators, or even a new class of personnel).

• For some advanced SMR designs, operators will face the challenge of supervising the operation of additional units as they are placed on-line. As the number of modules increases, the demands on the operators will change, and potentially the number of operators required for safe operation (that is, multiple staffing plans may be needed to address the addition of more units during the construction period or subsequent operating periods).

These challenges indicate that HSIs and their selection and deployment cannot be considered in isolation of the tasks and environments associated with them. It has to be an integral part of the HFE process, which, in turn, has to be integrated with the rest of the design organisation’s engineering processes.

The licensing issues related to SMRs are covered elsewhere in this Handbook, but for the human factors engineer it is essential to find an early resolution of regulatory issues regarding the use of new HSIs. Early resolution will enable designers to incorporate appropriate changes during the development of their concepts of operation, designs, task analyse, and staffing plans before submitting a design review or licence application. It will also support the NRC staff’s review of the design and license applications.