14.3.1 Development of advanced ICHMI

ICHMIs represent enabling technologies that can strongly impact reactor operations, performance, and safety. The A-SMRs as well as the LW-SMRs of the future will employ digital ICHMI systems. This fact coupled with a new paradigm of operating multi-modular units that may be used to produce electric power and process heat present new challenges. The ICHMI area potentially offers opportunities to offset the reduction in ‘economy-of-scale’ savings that come with the current large LWR central station plants where construction and operational costs are distributed over a larger number of megawatts of power in terms of design electrical rating (construction) as well for power production (operational). The following discussion on ICMHI R&D efforts under the ART program is drawn heavily from Wood [2, 3].

The ART ICHMI research area is defined by and structured based upon three principal drivers:

• unique operation and process characteristics;

• affordability — lower capital costs; and

• enhanced functionality.

Figure 14.1 illustrates and summarizes key technology issues that need to be examined and understood for each of these three drivers.

• Unique operation and process characteristics: SMRs in general have different process measurement needs from the current fleet of large LWRs. For A-SMRs using coolants (e. g., gas, liquid salt, liquid metals) other than water that will operate at higher temperatures, the process measurement instrumentation needs to be both chemically compatible with the coolant as well as tolerant of the higher temperature. Correspondingly, diagnostic measurements will differ for these A-SMRs. The unique, operational characteristics of most SMR designs are derived from the dynamic behavior of each general reactor class, e. g., gas-cooled, liquid metal-cooled, and differences in plant configurations. All SMR concepts will likely involve passive process systems to enhance safety. Thus, the impact of these passive systems on operability and plant performance needs to be evaluated to ensure proper consideration in control and safety requirements. Plant configurations that involve shared plant systems or resources among units, or integrated, reconfigurable balance-of-plant systems for multiple co-generation products require examination. Some SMR concepts involve sharing resources and systems among units to further reduce the up-front costs. This degree of sharing among units or modules for the purposes of reducing cost can range from minor support or auxiliary systems (emergency coolant tanks, control stations, backup electrical power, etc.) to major primary or secondary systems (e. g., turbine-generators coupled with two or more units). There may be significant dynamic coupling effects that must be taken into account within the operational controls for the plant depending on the extent of the sharing.

• Affordability — lower capital costs: ICHMI costs typically do not scale with the size of the reactor thus making them a larger cost element for SMRs in general than for large light — water reactors (LWRs). Consequently, using advanced technology effectively can help

reduce initial costs for example by minimizing cable runs and consolidating functions in highly reliable systems. Certain innovative technologies may also provide some benefit in reducing the fabrication, installation and inspection costs, financing costs, and operations and maintenance (O&M) costs. The most significant controllable contributor to day-to-day costs arises from O&M activities, which are heavily dependent on staffing size and plant availability.

• Enhanced functionality: Through application of advanced control schemes and predictive maintenance capabilities, one can minimize impacts in terms of reliability where multiple units or modules are employed. Advanced techniques for condition monitoring and reduction in reactor/system challenges via control system architectures can provide additional benefits. For those A-SMRs being used for both electric power production as well as process heat for hydrogen production or petrochemical processing where the demand for electric power and the process heat may vary, an advanced control system and integrated process diagnostics will be required. Multi-unit control with significant system integration and reconfigurable product streams has not been undertaken before. Obviously, these potentially new applications have significant implications for A-SMR system designs, construction, licensing, regulation, and operation.

Current ICHMI research areas are listed in Table 14.1, including a brief summary

of the scope for each research area.