Probabilistic Risk Assessment for Small Modular Nuclear Reactors Co-located with Integrated Energy System

Small modular nuclear reactors (SMNR) are being considered as dedicated thermal and electrical
energy for many industrial processes. The Department of Energy (DOE)’s integrated energy system
(IES) program supports the initial investigation of hazard analyses for co-located SMNRs and industrial
facilities such as oil and synthetic fuel refineries, methanol plants, and pulp and paper
mills. Comprehensive hazards identification and analyses, including accidentology, failure modes
and effects analysis, were performed to identify and analyze the external hazards presented by the SMNR’s customer
on the co-located SMNR. A publicly available probabilistic risk assessment
(PRA) model was developed for a modular high temperature gas-cooled modular reactor (mHTGR)
in the Idaho National Laboratory (INL) developed PRA software Systems Analysis Programs for
Hands-on Integrated Reliability Evaluations (SAPHIRE1
) based on the 1987 design from DOE. The mHTGR is one
of the SMNR designs that has a higher operating temperature than light water reactors (LWR) (up to 750ºC). The
higher temperature of the steam supply from mHTGR compared
with that of LWRs is advantageous for use in many industrial facilities. For instance, hydrogen can
be more efficiently produced via high temperature steam electrolysis (HTSE). The DOE’s light
water reactor sustainability program (LWRS) supported a conceptual design of a heat extraction
system (HES) connected between a LWR and HTSE. This HES conceptual design is borrowed for
the integration of an mHTGR and HTSE given a specific condition and assumption. This research demonstrates the
impacts of the failure of the HES on the mHTGR PRA outputs with and without consideration of the piping
components. The outcome of this research serves as the foundation for
(1) insights on the safe distance siting between the mHTGR and industrial applications, and (2) PRA
data for use in regulatory support of licensing acceptance for an SMNR site co-located with an industrial facility.