Advanced Reactor Development and Technology
Heavy Liquid Metal Reactor Development
Argonne has traditionally been the foremost institute in the US for development of technologies for
advanced nuclear power systems. The Heavy Liquid Metal Coolant (HLMC) reactor research initiative currently
underway is one element of ongoing efforts at Argonne to address reactor technologies that can fulfill
the requirements for nuclear power to be viable as an important energy resource for the 21st century,
both for domestic (U.S.) and international utilization. In this effort, reactor concepts are being
developed and evaluated in relation to proposed specific applications. One such concept is intended
to be a low-cost contender for commercial electricity production. The approach is to achieve capital
operating cost savings through extreme measures of simplifying the system: i.e., by providing a robust
system with minimal maintenance needs, providing a small, modular pool-type configuration that lends
itself to the economy of factory fabrication and overland transportation, and providing an extremely
long-life core design which eliminates fuel shuffling and partial reloads and requires refueling outages
only at very long intervals (~ 15 years). The reactor system is required to be exportable to developing
countries, and so the approach includes measures for proliferation resistance. The system described
(STAR-LM) is sized for the export market at 300-400 MWt; however, plant power can be varied for greater
needs by coupling multiple modules as was the approach for the PRISM reactor concept. In the particular
concept that is pursued, the design approach is limited to that which offers the possibility to achieve
deployment in an early time frame.
Small reactors using lead-bismuth eutectic (55 wt% Bi-45 wt% Pb; Tmelt = 125 C; Tboil = 1670 C) as a primary coolant were developed in Russia and successfully operated for many years. Lead-bismuth eutectic (LBE) does not react exothermically or vigorously with water or steam; it does not burn when exposed to air. This enables a radical simplification and cost savings for fast reactors through elimination of the need for an intermediate coolant system.
The Secure Transportable Autonomous Reactor (STAR) project addresses the needs of developing countries and independent power producers for small, multi-purpose energy systems, which operate nearly autonomously for very long term. The STAR-LM variant described here is a 300 to 400 MWt class modular, factory-fabricated, overland transportable, autonomous load following, and passively safe natural convection reactor concept that takes advantage of the intrinsic benefits of a fast neutron spectrum core utilizing high thermal conductivity nitride fuel and natural circulation heat transport using lead-bismuth eutectic coolant. STAR-LM has the potential of meeting all of the Generation IV goals. The fast spectrum converter reactor achieves long-term sustainability with a realistic 15-year ultralong core refueling interval for minimization of the radioactive waste stream, proliferation resistance, and high capacity. Steam generator modules are placed directly into the primary heat transport circuit and produce superheated steam. Natural convection heat transport at all power levels eliminates the need for main coolant pumps further contributing to cost competitiveness. Seismic isolation eliminates concerns about seismic and sloshing-related loads in the pool configuration.
The reactor module is functionally a "flow-thru fuel cartridge" that affords no access to any core materials. It is inserted into the larger coolant module vessel and is removable for replacement at the end of the 15-year core life. The used reactor module would be transported off of the site to a secure Regional Fuel Cycle Support Center for reprocessing under international oversight.
Autonomous load following, that is the ability of the reactor core power to adjust itself to match the heat removal, is a consequence of the fast core with its strong reactivity feedbacks. Power changes occur solely due to the effects of physical phenomena alone without operation of control rods or any inherent reactivity feedback from control rods induced by temperature variations.
Even end-of-spectrum postulated events such as loss-of-heat sink with failure to scram are terminated passively by inherent core power shutdown, and the reactor afterheat is passively rejected to the atmospheric air inexhaustible heat sink by guard vessel exterior cooling. The simplifications realistically contribute to reliable operation and economic competitiveness. Traditional benefits of liquid metal coolants (compact system design, low system pressure, and separate coolant and working fluids) are also preserved.
Reactor concept development has achieved 400 MWt power in a small module size based on preserving key criteria for: a) full spectrum of modes of module transport from factory to site (including rail transport); b) 100+% natural circulation heat transport; c) ultralong core cartridge lifetime; d) production of superheated steam for enhanced cycle efficiency; and e) coolant and cladding peak temperatures well within the existing (mainly Russian) database for LBE coolant and ferritic steel core materials.
To summarize, the STAR-LM concept of a small, transportable, economical, proliferation resistant reactor design appears to be achievable using existing technologies. The basic concept has now been developed. Iteration with core designers is continuing to optimize the design. Additional thermohydraulics analysis and control strategy studies are under way to further the concept development. The use of advanced energy conversion systems for a STAR-LM-based plant is also being investigated, with the aim of increasing the electricity conversion efficiency or producing alternative energy products such as hydrogen.
In the Press
Argonne’s David Wade: On the development of small modular reactors
from Nuclear News (Aug., 2004) [ PDF (514KB)]
Last Modified: Wed, September 15, 2010 6:54 PM