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‣ Balance of Plant elimination – Successfully completed “go/no-go” feasibility milestones – Retired technological risks with TRL=5 independently verified‣ Demonstrations via high-fidelity simulations and sub-scale helium closed-loop

simulator testing ‣ Transportable via shipping container (any site)

– after operation, spent-power modules shipped in shielded ISO Conex ‣ Integral, decoupled, power conversion system ‣ Securing funding to build full-scale system

CompressorStandard ISO container dimensions

Coupled Core

22MWt EFPY≥8 η > 40%

Direct-drive Compressor Independent of Power Turbine

Sealed fuel-cartridge and heat exchanger

High-speed generator

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The HOLOS Team brings a group of trusted DoD and DOE partners to deliver to a working prototype for all applications:

• Parsons: systems integrator and solution provider of FOAK nuclear facilities to DOE, infrastructure partner to NASA, and developer of $100M+ annually of DoD prototypes

• Honeywell: world’s leading manufacturer of Auxiliary Power Units (APU) deploying advanced small turbomachinery (e.g., Abrams M-1 tank), as well as systems & materials for space applications

• Siemens: global manufacturer, digital solutions and leading innovator in industrializing additive manufacturing for power and digital twins end-to-end systems

• HolosGen-F&A Technologies: technology specialist & designer of tailored-application microreactors, and innovative pioneer of highly integrated miniaturized power conversion sys

• ANL: DOE lab validation partner of HOLOS technology, engaged under the DOE ARPA-E MEITNER Program, performed and published results of high-fidelity neutronics & thermal-hydraulic modeling

• INL/NRIC: DOE lab sponsoring the National Reactor Innovation Center (NRIC) that will provide a testbed for nuclear prototype testing of novel small modular and microreactors

• ORNL: DOE lab specializing in SMR designs and codes development for variable load, high-efficiency turbomachinery components

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MOTOR AXIALCOMPRESSOR RECUPERATOR FC-HEX TURBOGENERATOR

SUPPLEMENTALCOMPRESSOR

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PHYSOR 2020: Transition to a Scalable Nuclear Future Cambridge, United Kingdom, March 29th-April 2nd, 2020

DESIGN OPTIMIZATION OF THE HOLOS-QUAD MICRO-REACTOR CONCEPT

N. E. Stauff1*, C. H. Lee1, A. Wells2, C. Filippone2

1 Argonne National Laboratory

9700 S. Cass Avenue Argonne, IL 60439, USA

2 HolosGen LLC Manassas Park, Virginia, USA

* nstauff@anl.gov

ABSTRACT

The Holos-Quad micro-reactor concept is proposed by HolosGen LLC to generate 22 MWt with a lifetime of approximately 8 effective full power years (EFPYs) for civilian applications. The design is based on a very innovative high-temperature gas-cooled reactor concept using four Subcritical Power Modules (SPMs) that fit into one commercial 40-foot transport ISO container. A rigorous design approach was employed in order to ensure that all input parameters were fully investigated and the best solutions possible were considered. The first step of this approach consisted of properly defining the Holos-Quad design problem by identifying the design objectives, the operational constraints, and the input parameters. In the second step, a sensitivity analysis was performed to enable a preliminary investigation of the input parameters to identify the correlations among input and output variables. Finally, the design optimization was performed in the third step, employing a genetic algorithm to effectively explore the highly constrained input parameters and find global optimal solutions. The multi-objective optimization identified various core solutions that would be optimum solutions for different types of applications. For applications where economics matters less and the ease of transportation matters more, a core weight of ~15 tons could achieve a lifetime of ~3.5 EFPYs. For applications where economics matters more and the ease of transportation matters less, a lifetime of 8.3 EFPYs could be achieved with a total core weight of ~26.7 tons.

KEYWORDS: micro-reactor, design optimization, HTGR

1. INTRODUCTION Micro nuclear reactors are being developed for different applications such as deployment in harsh locations, long-term electricity supply to remote areas, emergency power in response to a natural disaster, etc. For rapid deployment to locations where the external power grid is weak or inexistent and access to operation personnel is limited, a very small reactor in terms of power rate and physical size is favorable. A power rate less than 20 MWe with all components manufactured, assembled and tested at a factory are preferred, altogether with a high level of passive safety and an autonomous reactor control system. In this context, HolosGen LLC is developing the Holos-Quad micro-reactor concept, a very innovative high-temperature gas-cooled reactor concept using four Subcritical Power Modules (SPMs) that fit into one commercial 40-foot transport ISO container, to generate 22 MWt with a lifetime of at least 8 effective full power years (EFPYs) for electricity production to support civilian applications. Under the ARPA-E MEITNER program initiated in FY2019, the Argonne National Laboratory (ANL) design team has been contributing to the core

Core Design of the Holos-Quad Micro Reactor

Nicolas E. Stauff,* Changho Lee,* Ling Zou,* and Claudio Filippone†

* Nuclear Science and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA † HolosGen LLC, Manassas Park, VA, USA

nstauff@anl.gov

INTRODUCTION The Holos-Quad micro-reactor concept is proposed by

HolosGen LLC to generate 22 MWt (Mega Watt thermal) with a lifetime of approximately 8 effective full power years (EFPYs) [1]. The design is based on a very innovative high-temperature gas-cooled reactor concept using four Subcritical Power Modules (SPMs), each containing its own power conversion system executing a closed-loop Brayton cycle. The full system is designed to fit into one commercial 40-foot transport ISO container for ease of transportation.

The Holos-Quad core design is being advanced in collaboration with the Argonne National Laboratory under an ARPA-E MEITNER award. Initial core description was published in [2]. Additional optimizations of the core design were adopted since then. The objective of this paper is to provide an up-to-date description of the Holos-Quad core.

The design process of the Holos-Quad employed rigorous approach based on multi-criteria optimization to ensure that a very large spectrum of potential solutions was searched to down-select the best one [3]. High-fidelity simulations based on various computation codes were also used to confirm the performance obtained [4]. The neutronics design analysis of the Holos-Quad was completed and its latest core configuration is described in this paper.

CORE DESCRIPTION

The Holos-Quad is a high-temperature gas-cooled

reactor (HTGR) concept generating 22 MWt and designed to fully fit into one 40-foot transport ISO container. It uses TRISO fuel distributed in graphite hexagonal blocks and cooled with 7 MPa-pressured helium gas with core inlet/outlet temperature of 590/850 oC to enable thermal efficiency of the Brayton cycle of approximately 45% to produce approximately 10MWe (Mega Watt Electric) [5].

The Holos-Quad reactor core is formed by four independent SPMs to facilitate independent transportation of each SPMs in a shielded container. Each SPM contains

its own closed-loop, gas Brayton cycle with a turbine, compressor, inter-cooler and rejection heat exchanger, converting 5.5 MW thermal power into electricity. In one configuration of the Holos-Quad design [2] the SPMs are moved to control the reactivity of the core. The configuration of the Holos-Quad shown in Fig. 1 and utilized in this analysis employs fixed SPMs that are separated by a central reflector made of beryllium oxide that integrates the shutdown mechanisms in the form of absorbent rods, as shown in Fig. 2. Each SPM is wrapped inside a sealed shell to prevent outside air from interacting with graphite at a high temperature while limiting neutronic penalty. The full core cross-section fits inside 2.34×2.34 meter ISO container, and the total core active length is 3.7m, including 10cm-thick BeO axial reflectors on both ends of the driver fuel region.

In this configuration, the coupled Holos-Quad core contains 55 hexagonal graphite assemblies, surrounded by the BeO reflector. Each assembly contains 45 fuel blocks, 9 blocks of lumped burnable poisons, and 27 coolant channels (see Fig. 2). The fuel blocks contain TRISO-UCO fuel with HALEU at 19.95at% enrichment, and 40% packing fraction. Lumped burnable poisons use particles of B4C with packing fractions axially (6 regions per assembly), and radially (3 radial groups of assemblies) optimized to flatten the power of the core and minimize reactivity swing. High-pressure helium circulates in the coolant channels to transfer nuclear-generated heat to the power conversion cycle. Helium-coolant is contained inside a coolant sleeve technology to enable using an unpressurized SPM shell. The coolant sleeve technology eliminates erosion of graphite assemblies while enabling high coolant velocity and adding another containment barrier separating the fuel from the coolant.

Two reactivity control systems were selected using enriched B4C absorbing material. Eight rotating drums located in the radial reflector region to control the core power, and two independent sets of shutdown rods located along the central reflector region and outside of the SPMs shell.

‣ Comparative economic models, HolosGen Vs CSU Vs ANL <10% discrepancy‣ Discussions with Puerto Rico stakeholders via ARUP

Aspen Holos

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‣ Completed Q9‣ Advice: Identify opportunities for technical support from the Design Team and the

Resource Team as early as possible in your project

2018 2021