Nuclear Thermal-Electric Rockets

Perhaps a bit off topic but how much extra mass would it add to have a small parasitic closed loop power generator on the same hot core using maybe 1 percent total thermal energy to power the crew compartment when the craft isnt thrusting and doesn't have the main turbine spun up? Does it make more sense to have a seperate RTG to keep the lights on in the crew module?

matterbeam . Wilco. Lemme take a look. There was "stuff" about MITEE but I haven't looked at that concept for a long while...which is ironic because on my to-do-list is exactly re-looking at NTER. My boss challenged me on that some time ago.

My initial reactions are (NOT FINAL and only from a quick scan):
-Overall I really like it.
-All of the material in all of these "low tech" (I have to laugh here) NTR concepts (including CoaDE's model) are at ludicrously high temperatures. I recommend folks remind themselves about that alot. At least...when I talk about using stuff like is in CoaDE's cores at the temperatures that CoaDE uses them my material science people laugh at me. They tell me that I've forgotten things like the fact that many of the materials in question will be so malleable that they will no longer be structural.
-That you're overly harsh on bimodal. I persist in thinking that it's the best way (at current tech levels...possibly getting even better with higher tech levels) to achieve mission-specific Isp optimization. You say that all of the systems show compromised performance but what each of Stan's studies actually show is significant advantages over single moded systems in the cases studied.  Real practitioners in this area are quite actively interested in bi and trimodal systems to this day. The current NTP programs aren't starting with them because they're much more complex to design and build.
-Need to go back and read my MITEE notes to give detailed feedback.
-Additional issue with thermophotovoltaic - Not sure anyone knows how they'll behave in a neutron environment associated with a fission system. If they're like regular PV the answer is likely "poorly".

Bonus extra fun (not a comment on your blog) on liquid or vapor core designs = for fun go to a nuclear space propulsion conference and listen to a talk on liquid or gas core reactor. In the Q&A simply ask "what happens when you turn it off?" I got a good laugh from the presenter an audience. There's ALOT of HARD operational questions associated with those higher performance fission designs. Not saying don't use them...just saying that you might run into something like the Russians reportedly ran into with their liquid metal cooled Alfa submarine reactors. Sweet performance it's impossible to turn it back on if you ever shut it down completely.

-I think that your comparison understates the magnitude of the difficulties involved between chemical rockets and LCR/GCR by a good bit.
-The Alfas were lead-bismuth cooled. Wikipedia is fairly complete on this and you'll get a little on the trouble the Soviets and Russians had on maintaining them.
-Yet the second nuclear submarine the States built (SSN-575 USS SEAWOLF) was sodium cooled.

Uh, no?

Gas core might be relatively crazy idea, but it was relatively well researched with relatively detailed engineering done (it would doubtlessly face hundreds more "just engineering issue"s, but still).
With fusion we don't even know how to break even with the reaction other than either piling up stellar mass worth of fusile or hitting fusile with a nuclear explosion in just the right way.