----- Original Message ----- From: "Terry Blanton"
If I understand you, I can make a potbellied stove out of a chunk of uranium ore and a controllable neutron source. :-)
Hmm...How much reactor grade heavy water do you have on hand to fill it with?
Here is an overly simplified explanation of the 'secret' to the efficiency of the HWHR, and to its main deficiency, which keeps it from being used today for power.
Normal fission gives about 2.4 new neutrons for every fission neutron. With Nautral U, you immediatlely loose half of these to abosrobtion by other 238U atoms, and if you are not using heavy water or graphite as a moderator you CANNOT go critical, no matter how much fuel you have, as there are too many losses to keep the Keff over 1.
However...Uranium is a most remarkable element in that despite it being twice as dense as lead, mas o menos, it can still be turned into either a gas (molecular hexafloride gas) or even **dissolved** in water, as a nitrate. When dissolved in heavy water, where each uranium nitrate molecule is surrounded by several hundred deuterium nuclei within a few angstoms, something amazing happens on a fission reaction. Normally, of course you get two fission fragments and the 2.4 free (and fast) neutrons, but in a solution all 4.4 of these particles, moving at extremely high intial velocity can interact with the hundred or so deutrerium nuclei (they are now 'targets') withing the first nanometer and knock loose another neutron. This has the effect of raising the 2.4 free neutrons to [blip]. Athough I cannot disclose this secret number, let's just say that when low enrichment of even natural U is nitrated in such a reactor that you can still get near a Keff of .99 within your pot-belly-sized stove size factor, which is quite remarkable, if you think about the implications. But let's not go there.
The reason that this reactor cannot be used for power is that the reactivity is so great, that if you ever allow it to approach the critical regime, the moderator boils off, almost instantly and quenches the reaction. So inhernetly it cannot get hot and still oeprate. But...hello... we can still find a way to turn that lemon into lemonade !
The totally neglected use of the HWHR (heretofore) is solely as a small and efficient subcritical neutron multiplyer - always keeping the power level relativley low and the device cool, so that boiling does not occur. Our only purpose is to replace a billion dollar accelerator with a few half million dollar pot belly stoves.
Can you get enough neutrons out of Putterman's dilithium and maintain a safe Kaysubef?
Yes, but you probably wouldn't use that anyway, as it is unproven. There are plenty of commercial sources available now that will reliably give you several thousand neuts per sec to start off the linked and staged series of HWHR multipliers. Ironically, the biggest market for small neutron generators is in oil exploration.
Jones
