The Flexblue SMR concept is one of the most recent and more unique entries into the commercial SMR competition. Based substantially on submarine experience, the SMR is intended to be operated on the sea floor at a depth between 50 and 100 m. The 50 m upper limit isolates the plant from surface storm effects while the 100 m lower limit protects against excessive pressure on the 14 m diameter by 146 m long outer hull. The 160 MWe SMR can be deployed in multi-unit ‘farms’ that are remotely operated from a coastal command and control facility. A heavy lift cargo ship transports the module to and from its operating site. Refueling is expected to occur every two or three years, at which time it will be returned to a central facility for refueling and maintenance. Later versions of the transport ship may allow for refueling at the site of deployment. Major overhauls of the module are expected every 10 years. At the end of the module’s life, expected to be 60 years, the module is transported to a decommissioning facility for final disposal.

The ocean environment greatly simplifies traditional safety aspects of the design. The ocean water provides an assured ultimate heat sink and an additional barrier to fission products in the case of an accident. The passive safety systems ensure that

the module can survive an unlimited time without operator action or power following an accident. Key parameters and a representative graphic for the Flexblue design are given in Figure 2.4. [4]