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The busyness of the nuclear fuel supply chain
Ken Petersenpresident@ans.org
With all that is happening in the industry these days, the nuclear fuel supply chain is still a hot topic. The Russian assault in Ukraine continues to upend the “where” and “how” of attaining nuclear fuel—and it has also motivated U.S. legislators to act.
Two years into the Russian war with Ukraine, things are different. The Inflation Reduction Act was passed in 2022, authorizing $700 million in funding to support production of high-assay low-enriched uranium in the United States. Meanwhile, the Department of Energy this January issued a $500 million request for proposals to stimulate new HALEU production. The Emergency National Security Supplemental Appropriations Act of 2024 includes $2.7 billion in funding for new uranium enrichment production. This funding was diverted from the Civil Nuclear Credits program and will only be released if there is a ban on importing Russian uranium into the United States—which could happen by the time this column is published, as legislation that bans Russian uranium has passed the House as of this writing and is headed for the Senate. Also being considered is legislation that would sanction Russian uranium. Alternatively, the Biden-Harris administration may choose to ban Russian uranium without legislation in order to obtain access to the $2.7 billion in funding.
M. M. R. Williams
Nuclear Science and Engineering | Volume 143 | Number 1 | January 2003 | Pages 1-18
Technical Paper | doi.org/10.13182/NSE03-A2314
Articles are hosted by Taylor and Francis Online.
A model of neutron multiplication for aggregates of randomly placed fissile spheres with random material properties in a background medium is presented in terms of the transport equation. Two distinct problems are examined: (1) small spheres in an infinite bulk medium in which the total cross section in the spheres and bulk medium are the same and (2) small spheres in a void or purely absorbing medium but with different total cross sections in sphere and medium. In both cases we consider criticality in which there are random material properties of the spheres and random positions in the container. The random sphere problem is studied statistically by calculating the multiplication factor for many thousands of cases with different positions and material properties and, from the results, constructing a probability distribution function for the multiplication factor. Some of the results are also calculated using diffusion theory and therefore we are able to give guidance on the likely errors caused by diffusion theory in this type of problem.Although the problems are restricted to the one speed approximation, they may be applicable to fast neutron problems and we apply the work to spheres composed of random proportions of 235U and 238U. The work also has some bearing on the physical behaviour of pebble bed reactors which are of current interest, and in the storage of fissile waste. We have also discussed some of the underlying statistical problems associated with random arrays of spheres in a uniform lattice. In formulating our problem, we use the collision probability technique and as a by-product derive some new inter-lump collision probabilities for two spheres.