I agree with BJ. Luthor was a rotten snake all his life and he wanted to be prepared for anything.
Lois is almost playing this too cute. She's coming to rely on her partner's special abilities, and that might get her to take a chance or two she wouldn't have taken had she thought Clark was an ordinary man. Of course, this changes everything from here on out, doesn't it? How will she convince Clark that her feelings are for him and not for Superman? Will she pretend to be stunned when he tells her? And wouldn't that be just as dishonest as him not telling her before he asks her to marry him?
This situation solves some problems and reveals others. In the interest of fairness, she should probably tell him that she knows the secret before he embarrasses himself completely. And she should do it before she leads him on romantically, too. No sense making this any harder than it has to be.
Oh, the A-plot is fantastic, Nan. I'm ready to find out what's supposed to happen with the EMP satellites and how Superman is going to stop the blast.
There is actually some empirical evidence of what an EMP would do.
This site describes the probable worst-case scenario resulting from a nuclear blast over America, and it mentions a nuclear test over Johnson Island in the South Pacific in June 1962 which damaged electronics in Hawaii, a thousand miles away. That blast wasn't supposed to have that result, either. Surprise!
When's the next chapter coming up?
Should be fun to watch, either way!