The three major challenges for SMR deployment are as follows.

1.2.2.1 Sufficient reduction of financial risk

The investor-perceived financial risk arises from three key factors:

• NRC licensing requirements which could affect the capital as well as operating cost of these SMRs regarding plant staffing, security requirements, insurance and licensing fees, and decommissioning funding;

• the validity of the expected learning curve to reduce capital costs through factory manufacture;

• the more typical nuclear construction concerns, such as:

о construction and commercial operation schedule delay due to regulatory related delays,

о construction cost overrun due to constructor inexperience such as the current EPR Finnish and French construction activities and unforeseen mandated design enhancements such as those arising from the Fukushima accident, and о loss of investment due to operational and maintenance cost escalation or occurrence of a severe reactor accident.

All reactors are equally designed to a top level set of regulatory requirements, which however are not fully harmonized internationally. In the US these requirements have been made much more explicit for water-cooled reactors, since among the other coolants only the Fort St. Vrain helium-cooled reactor received a US Nuclear Regulatory Commission (NRC) (commercial) operating license. The explicit existing definition of water-cooled reactor regulatory requirements is a major benefit to light — water reactor (LWR) SMRs in comparatively assessing the licensability of other SMR coolant types. However, even for LWR SMRs the following factors significant to regulatory acceptance will need to be resolved:

• the reactor control strategy leading to reduction in the number of required operators;

• the reactivity control issues related to the desired long duration of the irradiation cycle to be accomplished by some designs without the use of soluble poisons;

• definition of the mechanistic source term for fission product release in a severe accident; and

• multi-module interactions.

Finally, LWR plant vendors are assuming that their designs will be accepted in a timely manner by the regulator. They base their optimism on the contention that their designs employ proven, current licensed concepts using proven components and systems configurations at power levels sufficiently low to allow the enhanced use of passive safety features which have already been reviewed and approved for the larger Generation Ш+ advanced light-water reactor (ALWRs). This assumption, even if proven correct, needs to reflect regulatory acceptance of at least some of the factors noted above cast in a manner yielding economic benefit to the SMR.

For SMRs using non-traditional coolants such as helium, sodium, lead-bismuth, or molten salts, the regulatory challenge is more difficult since the NRC staff lack familiarity with these reactor designs. Additionally, given the still largely prescriptive nature of light-water-based regulations in the US, the licensing process is not amenable to the newer more innovative designs. There have been calls for using a technology-neutral licensing process to license these new reactor concepts such that the inherent design features can be recognized by the regulator. The development of such a process is underway but is proceeding very slowly.