As Henry pointed out, the big issue is operating temperature. Heating air
for a jet engine cycle is one thing but heating hydrogen hot enough to make
a space rocket efficient enough to be practical was really on the bleeding
edge of material science at the time and probably is today. The Nerva
engines were a solid-state core with the exception of the rotating
beryllium/boron reflector/absorber scheme used to control neutron flux. A
key feature of the MSR design is that the fuel and coolant are effectively
the same working fluid. Pumping it into the core subjects it to a geometry
that is favorable for criticality. As soon as it leaves the core in the high
L to D plumbing, it becomes sub-critical again. This is an elegant design
feature for many applications as well as a safety feature if designed
properly. If the reactor and particularly all of the biological shielding
didn't weigh so much, it would have been the ticket for the proposed air
breathing jet engine cycles. The USAF just had to have a nuclear bomber so
they plowed on despite all the obvious silliness of the whole concept.
Rocket engine reactors did manage to achieve some impressive power densities
and compact designs during their development. I'm not aware of any
intentionally designed systems achieved that kind of performance. The
Russian RD-0410 managed to tweak out a bit more power by a clever core
design and the addition of a small amount of heptane to the hydrogen in the
cycle to prevent the core from eating itself. Again, by being able to run
hotter and in less space.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
<http://www.cesaronitech.com/> http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> On Behalf
Of George Herbert
Sent: Friday, July 12, 2019 3:43 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: MSR reactors.
I'm moderately familiar with them, but most recently from the
nonproliferation risks side of things. I hadn't been thinking about space
propulsion, but that's a good thing to consider sometimes...
Considering it, just idly thought up idea of MHD pump fountaining liquid
fuel into a gas flow might avoid some of the issues that the other liquid
approaches suffered, where they were trying to flow gas up through the
centrifugally contained liquid fuel.
Not sure what downsides might be.
On Fri, Jul 12, 2019 at 11:44 AM Anthony Cesaroni <anthony@xxxxxxxxxxx
<mailto:anthony@xxxxxxxxxxx> > wrote:
