The technology of micro heat pipe cooled reactor: A review

The Baseline Values and Assumptions Document (BVAD) provides analysts, modelers, and other life support researchers with a common set of values and assumptions which can be used as a baseline in their studies. This baseline, in turn, provides a common point of origin from which many studies in the community may depart, making research results easier to compare and providing researchers with reasonable values to assume for areas outside their experience. With the ability to accurately compare different technologies' performance for the same function, managers will be able to make better decisions regarding technology development.

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Life Support Baseline Values and Assumptions Document

The Heatpipe Power System (HPS) is a near-term, low-cost, space fission power system that has been under development at Los Alamos National Laboratory (LANL) for 5 years. The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably. The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing. If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out inexpensively and quickly and thorough testing of the actual flight unit can be performed—which is a major benefit to reliability. Over the past 4 years, LANL has conducted three HPS proof-of-concept technology demonstrations—each has been highly successful. The Heatpipe-Operated Mars Exploration Reactor (HOMER) is a derivative of the HPS designed especially for producing electricity on the surface of Mars. The key attributes of the HOMER are described in this paper, as well as a 20-kWe point design, system scalability, and the current technology status.

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The heatpipe-operated Mars Exploration Reactor (HOMER)

Ambitious solar system exploration missions in the near future will require robust power sources in the range of 10 to 200 kWe. Fission systems are well suited to provide safe, reliable, and economic power within this range. The Heatpipe Power System (HPS) is one possible approach for producing near-term, low-cost, space fission power. The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably. The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing. If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out quickly and inexpensively, and thorough testing of the actual flight unit can be performed—which is a major benefit to reliability. Over the past 4 years, three small HPS proof-of-concept technology demonstrations have been conducted, and each has been highly successful. The Safe Affordable Fission En...

Design and analysis of the SAFE-400 space fission reactor

This paper reviews the smallness, modularity and reactor-design aspects of emerging small modular reactors (SMRs). It is shown that small (whether in physical size or power level) reactors are not new, but offer economic and flexibility advantages that allow their use in a variety of applications. The different definitions of modularity are reviewed, including modularity in design, process intensification, manufacturing and construction. It is shown that these forms of modularity when applied to SMRs have some advantages, but also have some challenges that need to be addressed if their full potential is to be realized. Even if these forms of modularity are not fully utilized, the lower power ( ≤ 300 MW electrical) of SMRs allows the formation of larger power plants by incremental addition of reactor units, in the so-called scale modularity. The paper reviews the unique features of emerging SMR designs, and compares them to those of the early era of nuclear power. It is shown that while many modern SMR designs incorporate well-proven features that were tested and proven in early reactors. others introduce aspects of Generation IV reactors, in terms of inherent and/or passive safety. Given the promise of SMRs as means to reduce greenhouse gas emissions and their ability to supply reliable and base-load power, the licensing of such reactors by national regulators will provide a boost to their acceptability and adaptability as a player in combating climate change.

Emerging small modular nuclear power reactors: A critical review

An important niche for nuclear energy is the need for power at remote locations removed from a reliable electrical grid. Nuclear energy has potential applications at strategic defense locations, theaters of battle, remote communities, and emergency locations. With proper safeguards, a 1 to 10-MWe (megawatt electric) mobile reactor system could provide robust, self-contained, and long-term power in any environment. Heat pipe-cooled fast-spectrum nuclear reactors have been identified as a candidate for these applications. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than “traditional” reactors. The goal of this project was to develop a scalable conceptual design for a compact reactor and to identify scaling issues for compact heat pipe cooled reactors in general. Toward this goal two detailed concepts were developed, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials and a power level of about 5 MWe. A series of more qualitative advanced designs were developed (with less detail) that show power levels can be pushed to approximately 30 MWe.

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Design of megawatt power level heat pipe reactors

A mobile heat pipe cooled fast nuclear reactor may be configured for transportation to remote locations and may be able to provide 0.5 to 2 megawatts of power. The mobile heat pipe cooled fast reactor may contain a plurality of heat pipes that are proximate to a plurality of fuel pins inside the reactor. The plurality of heat pipes may extend out of the reactor. The reactor may be configured to be placed in a standard shipping container, and may further be configured to be contained within a cask and attached to a skid for easier transportation.

Mobile heat pipe cooled fast reactor system

The next generation of robotic missions to Mars will most likely require robust power sources in the range of 3 to 20 kWe Fission systems are well suited to provide safe, reliable, and economic power within this range The goal of this study is to design a compact, low-mass fission system that meets Mars-surface power requirements, while maintaining a high level of safety and reliability at a relatively low cost The Heatpipe Power System (HPS) is one possible approach for producing near-term, low-cost, space fission power The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out quickly and inexpensively, and thorough testing of the actual flight unit can be performed—which is a major benefit to reliability Over the past 4 years, three small HPS proof-of-concept technology demonstrations have been conducted, and each has been highly successful The Heatpipe-Operated Mars Exploration Reactor (HOMER) is a derivative of the HPS designed especially for producing power on the surface of Mars The HOMER-15 is a 15-kWt reactor that couples with a 3-kWe Stirling engine power system The reactor contains stainless-steel (SS)-clad uranium nitride (UN) fuel pins that are structurally and thermally bonded to SS/sodium heatpipes Fission energy is conducted from the fuel pins to the heatpipes, which then carry the heat to the Stirling engine This paper describes the attributes, specifications, and performance of a 15-kWt HOMER reactor

Design of a heatpipe-cooled Mars-surface fission reactor

A Mars surface power system configuration with an output power of 3 kWe and a system mass of 775 kg is described. It consists of a heatpipe-cooled reactor with UN fuel coupled to a Stirling engine with a fixed conical radiator driven by loop heat pipes. Key to achieving this low mass is the use of a highly radiation-resistant multiplexer for monitoring and controlling the reactor, as well as radiation resistant generators and motors. Also key is the judicious placement of shields to prevent radiation scattered from the Martian surface and air from damaging the reactor controls. Several alternate configurations also are briefly looked at, including a moderated reactor with UZrH fuel and a reactor using 233U instead of 235U. The moderated reactor system has essentially the same mass as the baseline unmoderated UN system and yields the same radiation shielding requirements. The 233U reactor is significantly smaller and yields a system mass about 228 kg lighter than with 235U, but part of this weight reduction is due to the use of removable neutron absorbers to assure subcriticality with water immersion, as opposed to permanently placed absorbers.

Small fission power systems for Mars

Interest continues to increase in using fission reactors to power robotic missions to Mars within the next decade, as well as manned missions in the future. This paper evaluates the use of the Heatpipe Power System (HPS) for these missions (the paper focuses on the reactor core, and does not significantly evaluate power conversion and shielding possibilities). The HPS is a safe, simple reactor that is designed to have a low development time and cost. Previously, most HPS designs have used refractory metals to allow high-temperature operation (for increased power conversion efficiency) and higher thermal conductivity. For use on Mars, a stainless-steel or super-alloy system may be required in order to avoid corrosion. As a result, Los Alamos National Laboratory (LANL) has begun a program to evaluate and test a stainless-steel HPS core. This paper will describe some analysis of potential non-refractory HPS designs, as well as work that is currently underway to build a full-scale unfueled HPS core. Resistance heated testing will be used to evaluate the thermal performance of the core under a wide variety of conditions; including the simulated Martian atmosphere. Analytical and experimental results thus far indicate that the HPS is very well suited for Martian applications. A near-term, low-cost, low-risk design is proposed for a Mars Outpost application that could provide 40 kWt, and thus 2 kWe with 5% efficient thermoelectrics. A higher power core, 350 kWt, is proposed as a potential surface power source for a manned Mars mission that could provide up to 100 kWe, depending on the efficiency of the power conversion system.

Robert S. Reid

Papers

Design of megawatt power level heat pipe reactors

Mobile heat pipe cooled fast reactor system

Design of a heatpipe-cooled Mars-surface fission reactor

Small fission power systems for Mars

The Heatpipe Power System (HPS) for Mars outpose and manned Mars missions