Re: social impacts — definitely something that this particular study did not look at, at all. As a National Academy of Sciences study from 1986 on the Medical Implications of Nuclear War noted:

"Perhaps the most serious shortcoming we have found in the works cited above is the lack of social science input. Except for Katz (1982), economic projections are made without even a passing reference to behavioral and institutional considerations. One thing is clear. A nuclear exchange of the magnitude reported in these studies would cause a rapid collapse of the nation's social and economic infrastructure. The speed with which a new system could be erected is an open question, and one which may never be answered."

For psychological impacts, I'm not sure there are great ways to know. There are studies (notably those by Robert Jay Lifton) that looked at the impact of the atomic bombings on the psychology of Hiroshima and Nagasaki survivors (and were important for the development of PTSD as a diagnostic category). But of course Hiroshima and Nagasaki, as horrible as they were, are quite localized compared to the total destruction contemplated in these later war scenarios, and were studied at a time in which the US Occupation had taken over the job of stabilizing postwar Japan, charting paths forward, and so on. And they were also attacks on a people who were already in a context of being bombed, as a nation. Would any results there be comparable or generalizable to Cold War (or later) Americans who suddenly found their world destroyed over the course of a matter of hours? I don't know. I don't know if it's possible to know. In fact, I'd rather keep on NOT knowing...

But I will be writing something on the "survivors would envy the dead"/"I'd rather go out in the flash" trope. My sense, as a historian, is that on average the will to survive is pretty strong, even in the face of unimaginable loss. People tend to underestimate it when it is posed in the abstract, or as a hypothetical, and are more resilient in practice, after the immediate shock of change has passed.

The US did put a lot of work into "continuity of government" plans, so that the core federal government could hypothetically survive such an attack. How well that would work, and of what good it would be, I don't know. I have always thought the idea of Congress hiding out in its bunker, nominally pretending to be important and relevant to a ruined nation, somewhat grim and unlikely.