ORNL-5388 - the Molten Salt Energy Technologies Web Site

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would be quite difficult and would require increasing technological sophistication; how-
ever, adding centrifuges would require only that the same device be duplicated as many
times as necessary. Increasing the tails assay would require more feed material.
Finally, in considering the potential circumvention of the isotopic barrier, it is
important to anticipate the enrichment technologies that could exist in 20 to 25 years -
the time when the denatured fuel cycle could be deployed. Technologically advanced
countries already have the necessary technological base to design and construct centri-
fuges, and many presently developing countries may have acquired the technology base by
that time. Countries with a primitive technology are unlikely to use this route, since
even with the financial assets and technically competent personnel they would have the
difficult task of developing the requisite support facilities. Other potential isotope
separation techniques are under development in many countries. Laser isotope separation
(LIS), plasma techniques, aerodynamic methods, chemical techniques, and electromagnetic
separation methods currently show varying degrees of promise.
these methods is discussed in Appendix A.
The current status of
It is impossible to predict the ultimate
success or failure of these alternative methods, and hence the isotopic separation
capability which might exist in 25 years is even more difficult to estimate. Current
estimates for the U.S. development program in LIS and plasma methods suggest that it will
be at least ten years before such methods could be operative on a working industrial
I basis, even with a highly sophisticated R&O effort.
7.1.2. Gamma-Radiation Barrier of Fresh Fuel
The production of 233U results in the concomitant production of a small but radio-
actively significant q2antity of 232U through the 232Th(n,2n) reaction [and the 230Th(n,y)
reaction if 230Th i s present in the thorium].
daughter products, the gama activity of the 233U-containing fuels increases, thus providing
a radiation barrier much more intense than is found in other fresh fuels.
could be employed to remove the 23211 decay products, such a procedure would provide a relatively
low radioactivity for only 10-20 days, since further decay of the 232U present in the fuel
would provide a new population of 228Th and its daughters, the activity of which would con-
tinue to increase in intensity for several years.
As the 232U decays through 228Th and its
While chemical processing
The concentration of 232U in the recycle fuel is usually characterized as so many
parts per million (ppm) of 2sU in total uranium. Due to the threshold nature of the
232Th(n,2n) reaction, the 232u concentration varies with the neutron spectrum of the
reactor in which it is produced. It also varies with the amount of recycle. For 12%
23% denatured fuel, the 232U concentration (in ppm U) ranges from 250 ppm for LWR-
produced 233U to a maximum of 1600 ppm for certain LMFER-derived denatured fuels (see
Section 3.1.3).
the 232U concentration would be approximately 8000 ppm, and thus the material would be
highly radioactive.
If the latter material were enriched to produce weapons-grade material,