In the conversion chain of 232Th to 233U, 233Pa is formed as an intermediate, which has a relatively longer half-life (~27 days) as compared to 239Np (2.35 days) in the uranium fuel cycle thereby requiring longer cooling time of at least one year for completing the decay of 233Pa to 233U.
http://indico.cern.ch/getFile.py/access?contribId=11&sessionId=3&resId=1&materialId=slides&confId=222140 If this is not done, the breeding ratio takes a major hit. If this is done, at the end of the year, we have the world’s best pure bomb material with little U232 protection. No thorium reactor designer will include this step in their design. The best way to go is to use fusion as a neutron source. The fusion reactor designers always fail to mention that they depend on thorium to increase their Q by a factor of 20. https://lasers.llnl.gov/about/missions/energy_for_the_future/life/ For example, Laser Inertial Fusion Energy (LIFE) project for the National Ignition Facility (NIF) effort is not mentioned in the propaganda articles that support NIF. They must use thorium pellets to increase their Q. The guy who heads that project is a con man because if the greens knew that his life reactor used thorium, they would be greatly disturbed. A fusion thorium hybrid as in LIFE was the way to go because the U232 levels from 14Mev neutrons are very large. Bomb potential is very small, but not now. Having recently found out now using cold fusion, U232 can be effectively removed from U233 making even fusion produced U233 bomb capable. This is why thorium has been removed from my agenda. On Mon, Jan 6, 2014 at 10:07 PM, <[email protected]> wrote: > In reply to Axil Axil's message of Mon, 6 Jan 2014 19:34:06 -0500: > Hi, > >The neutron budget in the thorium fuel cycle is very weak. At best with > >proliferation sensitive fuel reprocessing, the breeding ratio is 1.06 to > >1.14, but in reality it gets no greater than 1.06 to make the thorium fuel > >cycle proliferation safe. > > > > > > > >To make thorium a breeder we need to add U235 and/or Pu239 to get the > >breeding ratio high enough to burn Np237. That is why Np237 is removed, to > >save neutrons. > > It seems I was wrong about 237Np anyway. Upon checking I find that the > radiative > capture cross section for thermal neutrons is 164 barns, while the fission > cross > section is only millibarns. It is (strangely?) 238Np that is fissile. > > > > > >If we burn Np237, we must add more U235 on Pu239 to get the neutron budget > >over one. > > Understandable given the high capture cross section. > > > > >Thorium is usually tied to an ADS or Fusion neutron generator because of > >its weak breeding ratio. > [snip] > ...surely this is only initially necessary? I was under the impression > that 233U > actually produced fractionally more neutrons that 235U, implying that once > enough had been produced, you could enrich with 233U rather than 235U or > Pu. > Or is this a long term losing proposition, i.e. you can never breed enough > to > keep the process going? > > BTW, what does the "we" imply? ;) > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/project.html > >
