I wonder how much advancement has occurred since the early 1970s, when the NERVA fission rocket motor was fired-up on a test stand on Earth. We have learned a lot since then, so I am wondering if Lockheed Martin is just dusting off the NERVA rocket motor, or redesigning the whole thing.
As for the orbit and the statement that it will not reenter for a period "long enough to ensure that all of its nuclear fuel is spent when it comes down," that is
not the real issue. Unfissioned uranium getting vaporized in the atmosphere is not as big a problem as the products of the uranium that did fission getting vaporized in the atmosphere. So, what they need to talk about is the amount of radioactivity in the fission products, not the unfissioned fuel. See
https://en.wikipedia.org/wiki/Nuclear_fission_product , which says " the total radioactivity of a mixture of pure fission products decreases rapidly for the first several hundred years (controlled by the short-lived products) before stabilizing at a low level that changes little for hundreds of thousands of years (controlled by the seven long-lived products)."
So, the real issue is how much of what nuclear fission product isotopes are going to be released into the atmosphere. There are a lot of different elements in fission waste, some of which are highly bioactive. And, they are not "all gone" after a half-life, some is left for a long time - half of what was left after the previous half-life will still be around after the next half-life.
Or, worse, what if this rocket motor holds together during reentry, and we end up with all of that "nuclear waste" landing in a big lump somewhere?
I would like to see an engineered waste control plan for this thing before we launch it.
Facebook
Twitter
Instagram