Some good books on nuclear reactors (some of these are out of print):
V.M. Chernousenko, Chernobyl: Insights from the Inside. A very good (if not well organized) description of the Chernobyl accident.
Paul R. Josephson, Red Atom. History of the Soviet atomic energy program.
Kenneth Lish, Nuclear Power Plant Systems and Equipment. Chapter 3 is all about the type of reactor that’s currently going pear-shaped in Japan; there are other chapters on seismic safety and emergency cooling that are also apropos.
Richard Rhodes, The Making of the Atomic Bomb. Highly recommended summary of (ahem) applied nuclear technology; really a great read, with a lot of good background material on the physics.