Robin van Spaandonk wrote:
In reply to Edmund Storms's message of Wed, 28 May 2008 21:13:05 -0600:
Hi Ed,
Vortex is bouncing my posts again, could you forward this for me?
[snip]
Robin,
If this energy is produced by a nuclear reaction, then neutrons and
gamma are produced.
It clearly is a nuclear reaction, because "moderator" implies neutrons.
The Hydrogen (Deuterium?) atoms serve as a moderator, because protons have
almost the same mass as neutrons, which means that when a fast neutron hits a
proton, the neutron "stops", and the proton absorbs almost all of the energy,
which it then rapidly loses through ionization of the surrounding atoms.
IOW a single collision can be enough to thermalize a neutron. This *may* mean
that little neutron shielding is required, particularly if the outer shielding
is rich in protons, and contains no fissionable material (e.g. plastic).
This reactor is no different from normal reactors. It produces neutrons
and gamma. The only thing that makes it less dangerous is its small
size. Nevertheless, it is considerable source of radiation that needs to
be kept under observation and control. The size is similar to a ship
reactor, but such reactors are designed to be observed and serviced. The
proposed reactor is to be buried, out of sight and out of mind.
This requires significant shielding. In addition,
the "core" would be too active to dig up in five years and haul away for
reprocessing, at least right away.
Of course the whole thing is dug up, but the core is still very
radioactive. This can only be protected by significant shielding, which
adds to the weight and cost. Imagine the political problems of
transporting a potentially active reactor that contains massive amounts
of radioactive material.
It isn't the "core" that gets dug up, it's the entire reactor, shielding
included. The gammas would be shielded by burying the thing underground. If the
reactor output can be varied, then it can probably also be "turned off", which
would kill off the prompt gammas, though there would still be the gamma output
from the daughter nuclides to deal with after shutdown. This could indeed make
transport tricky.
In addition, the electric conversion
equipment would have to be contained in the shielded structure to avoid
releasing radioactive materials.
Not necessarily. One would just need the first level heat exchanger to be
internal, so that the fluid exiting the reactor never actually comes in contact
with the fuel.
But what transports the heat within the reactor? Water can not be used
because a leak would be catastrophic. Helium or hydrogen might work, as
you note, but it would have to be pumped, requiring equipment that could
never be serviced while being exposed to intense radiation. I suggest,
too many engineering problems exist in this design to make it economic
as a nuclear reactor. That is why I expected this to be a chemical
source of energy. Perhaps, as Jones suspected, this is only a dream
being used as a method to extract money from the uneducated.
I called the company and talked to a phone-answering person who said
someone would get back to me. Heard nothing yet.
Regards,
Ed
This means the energy conversion
process needs to be completely automatic. While I agree, the hydride
would make the nuclear reaction fail-safe, it does not solve the
significant engineering problems the design would have. UH6 is not used
in conventional nuclear reactors in spite of the fail safe nature
because it is very reactive to water and air.
Perhaps they use Helium cooling.
The danger is too great
when water cooling is used. One has to ask how the cooling is
accomplished on this design?
Good question. Note however that they still don't have regulatory approval.
Perhaps for the very reasons you state.
[snip]
Regards,
Robin van Spaandonk
The shrub is a plant.
