Description of the generic fluoride-cooled high-temperature reactor (gFHR)

Contact: Dr. Mustafa Jaradat (INL), [email protected]

Sponsor: Dr. Steve Bajorek (NRC)

Model summarized, documented, and uploaded by Dr. Mustafa Jaradat and Dr. Samuel Walker

Model link: Griffin-Pronghorn Steady-State Model

The gFHR is a pre-conceptual design of a fluoride salt cooled high temperature reactor based on material publish by Kairos Power (Satvat et al., 2021). The geometry is shown in Figure 1.

Figure 1: gFHR conceptual design from (Ortensi et al., 2023).

The main gFHR reactor specifications are shown in Table 1. This design relies on a multipass strategy in which the pebbles are discharged at the top of the active core and then reintroduced uniformly at the bottom of the core. The pebbles are buoyant and float toward the top of the core. The pebbles undergo an average of eight passes before they are discharged. The recirculation, evaluation, and disposal tasks are performed by the pebble handling and storage system (PHSS). During the evaluation task, the PHSS determines if the pebble has achieved the desired design burnup, at which point it is either discharged or recirculated back to the bottom of the core. Note that the average residence time in the original journal article (Satvat et al., 2021) was approximated between 490 and 550 effective full power days (EFPD).

This benchmark uses a single pebble design or type. The pebble specifications are shown in Table 2. The pebble includes a spherical lower density center graphite core for buoyancy, followed by a spherical shell that contains the TRISO particles and an outer spherical graphite shell.

The TRISO design specifications are included in Table 3. These specifications are based on the oxycarbide fuel testing from the Advanced Gas Reactor development and qualification program (AGR) AGR-2 irradiation campaign (EPRI, 2020) with the carbon content set to the upper limit of the AGR testing envelope.