Generic Heat Pipe Microreactor (gHPMR) Model Reactor Description

The generic Heat Pipe Microreactor (gHPMR) Model is based on ™ Westinghouse Electric Company's eVinci microreactor design. The ™ eVinci design has potential for autonomous operation, is intended for factory fabrication, and has a lifetime of 10 years, after which the entire reactor would be returned to the factory for either refueling or storage Clark et al. (2020).

Fuel, moderator, and heat pipes are arranged in a hexagonal lattice. The hexagonal core sits in steel monolith (graphite in Ortensi et al. (2024)). The monolithic microreactor concept utilizes a monolithic metal structure to support the fuel assemblies and evaporator sections of the heat pipes. Control drums are embedded inside the radial reflector sections. A central rod is used to start up and shut down the reactor. Sodium is utilized as the heat pipe working fluid. Heat pipes protrude from both ends of the core, allowing for two primary heat exchangers (only one in Ortensi et al. (2024)), one at each end of the monolith.

Below are the design specifications for the gHPMR model.

Table 1: Design specifications for the gHPMR model, from Ortensi et al. (2024).

General Design Specifications	Value
Thermal Power	15 MW(th)
Core Height	1.8 m
Core Height (Active)	1.6 m
Reflector Height	0.2 m
Core Radius	1.4 m
Canister Radius	1.468 m
Fuel Enrichment	10 w / o
Number of Heat Pipes	876
Number of Fuel Assemblies Types	2
Number of Standard Fuel Assemblies	114
Number of Control Rod Fuel Assemblies	13
Fuel Assembly Pitch	17.368 cm
Pin Pitch	2.782 cm
Fuel Compact Hole Radius	0.95 cm
Heat Pipe Hold Radius	1.07 cm
Number of Control Drums	12
Control Drum Diameter	28.1979 cm
Control Drum B $var element = document.getElementById("moose-equation-9a85ce0c-fc5d-449f-9c3b-afff78083421");katex.render("{_4}", element, {displayMode:false,throwOnError:false});$ C Layer Thickness	2.7984 cm
Control Drum B $var element = document.getElementById("moose-equation-358c870b-c235-4ac6-b708-88f4b615a936");katex.render("{_4}", element, {displayMode:false,throwOnError:false});$ C Angular Extension	120 $var element = document.getElementById("moose-equation-914db5be-b241-42dc-8658-d1dbe2ecd1b7");katex.render("^{\\circ}", element, {displayMode:false,throwOnError:false});$

Heat Pipe Specifications	Value
Working Fluid	Sodium
Wick Material	SS 316
Cladding Material	SS 316
Evaporator Length	1.8 m
Adiabatic Length	0.4 m
Condenser Length	1.8 m
Outer Cladding Radius	0.0105 m
Inner Cladding Radius	0.0097 m
Outer Wick Radius	0.0090 m
Inner Wick Radius	0.0080 m
Wick Porosity	0.7
Wick Permeability	2E-9 m $var element = document.getElementById("moose-equation-ae0739d2-8d91-4cb2-b436-e21e8f8ccce7");katex.render("^{2}", element, {displayMode:false,throwOnError:false});$
Pore Radius	1E-9 m
Wick Fill	100% overfill by volume at 500 K

Compact and TRISO Specifications	Value
Compact Fueled Zone Radius	0.875 cm
Compact Non-Fueled Zone Radius	0.9 cm
Compact Packing Fraction	40%
UCO Kernel Radius	0.02125 cm
Buffer Radius	0.03125 cm
Inner PyC Radius	0.03525 cm
SiC Radius	0.03875 cm
Outer PyC Radius	0.04275 cm

Operating Conditions	Value
Average Temperature	1073.15 K
Condenser Convection Temperature	523.15 K
Condenser Convection heat transfer coefficient	312.4 W/(m $var element = document.getElementById("moose-equation-68f766ec-04c6-4fef-852a-6e3725708af3");katex.render("^{2}", element, {displayMode:false,throwOnError:false});$ - K)

References

Andrew Clark, Bradley A. Beeny, Kenneth C. Wagner, and David L. Luxat. Technical and licensing considerations for micro-reactors. Technical Report SAND2020-4609, Sandia National Laboratory, 4 2020.

@techreport{eVinci,
    author = "Clark, Andrew and Beeny, Bradley A. and Wagner, Kenneth C. and Luxat, David L.",
    institution = "Sandia National Laboratory",
    title = "Technical and Licensing Considerations for Micro-Reactors",
    year = "2020",
    month = "4",
    number = "SAND2020-4609"
}

Javier Ortensi, Mustafa K. Jaradat, Joshua Hansel, and Stefano Terlizzi. The monolithic heat pipe microreactor reference plant model. Technical Report INL/RPT-24-77914, Idaho National Laboratory, 4 2024.

@techreport{gHPMR_main,
    author = "Ortensi, Javier and Jaradat, Mustafa K. and Hansel, Joshua and Terlizzi, Stefano",
    institution = "Idaho National Laboratory",
    title = "The Monolithic Heat Pipe Microreactor Reference Plant Model",
    year = "2024",
    month = "4",
    number = "INL/RPT-24-77914"
}

References