What I found so interesting about it, is the "burn wave" idea: it relates to another topic I have been interested in the past, that of the so-called geo-reactor (see http://www.nuclearplanet.com )
I was surprised to find that these old links, stored away in the memory of my computer, are still not broken
Completely Automated Nuclear Reactors for Long-Term Operation II: Toward A Concept-Level Point-Design Of A High-Temperature, Gas-Cooled Central Power Station System
UCRL-JC-122708 Pt 2 PREPRINT
Muriel Y. 'Yuki' Ishikawa
Stanford University, Stanford, CA 94305-6010
Roderick Hyde and John Nuckolls
University of California Lawrence Livermore National Laboratory, Livermore, CA 94551-0808
This paper was prepared for invited presentation at the plenary session of the 1996 International Conference on Emerging Nuclear Energy Systems (ICENES'96), Obninsk, Russian Federation 24-28 June 1996, and is the full version, an abbreviated form of which will appear in the conference proceedings.
Our current reference-design reactor contains a cylindrical core comprised of a small nuclear ignitor and a much larger nuclear burnwave-propagating region. The latter contains natural thorium or (possibly depleted) uranium fuel, and functions on the general principle of fast breeding. The entire core is surrounded by a neutron reflector and a radiation shield. Uniform temperature throughout the core is maintained by a large multiplicity of thermostating modules which, through the action of simple automatic controls transporting isotopically-enriched lithium when the local material temperature rises into the regime corresponding to a coolant-gas-temperature design-value of ~1000 K, depress the local neutron flux and thereby reduce the local power production. Triply-redundant primary means of transporting heat up to the generating station are provided, and entirely independent, triply-redundant energy-dumping means are included in this design to passively transport afterheat out of the core in the event of a loss-of-coolant accident or after the end-of-operational-life.
Such a reactor must be a breeder, for reasons of efficient nuclear fuel utilization and of minimization of requirements for isotopic enrichment. It must be a fast breeder because the high absorption cross-section of fission products for thermal neutrons does not permit the utilization of more than about 1% of thorium (or of the more abundant uranium isotope, U238, in uranium-fueled versions), without removal of fission products.
At the commencement of the reactor's operational life, the centrally-positioned nuclear ignitor module is driven critical by one-time removal of neutronic poison and, through concurrent nuclear fission and high-gain breeding actions, commences to launch a nuclear deflagration wave into the adjacent unenriched fuel. This wave first diverges radially from the centrally positioned, on-axis nuclear ignitor until portions of it reach the outer edge of the cylindrical fuel mass, where it is resolved into two oppositely-directed, axially-propagating waves. One such wave moves toward each of the two ends of the cylindrical core at a (exceedingly low peak) speed determined at all times by the instantaneous thermal power demand on the reactor (and upper-bounded by the leisurely beta-decay of Pa233, the rate-limiting step in Th232-U233 breeding).
Fuel moderately enriched in fissile material is generated behind each of the two wave-fronts. These two increasing masses of enriched fuel then continue to burn, until fission product accumulation and fertile isotopic depletion (at a 50% core-averaged fuel burn-up) finally drives the core's neutronic reactivity negative. Figure 5 illustrates typical conditions ahead of, within, and behind this pair of nuclear deflagration waves, and Appendix B discusses core nucleonics in more detail.