This is a complex subject that I don’t know enough about. But it’s still probably a good time to mention some statements from the international community regarding attacks on peaceful nuclear facilities.
One of the more salient is paragraph 75 of the 2010 NPT RevCon final document:
bq. The Conference considers that attacks or threats of attack on *nuclear facilities devoted to peaceful purposes* jeopardize nuclear safety, have dangerous political, economic and environmental implications and raise serious concerns regarding the application of international law on the use of force in such cases, which could warrant appropriate action in accordance with the provisions of the Charter of the United Nations. The Conference notes that a majority of States parties have suggested a legally binding instrument be considered in this regard.
Notably, the 2000 RevCon “final document”:http://www.un.org/disarmament/WMD/Nuclear/2000-NPT/pdf/FD-Part1and2.pdf said much the same thing.
It’s also worth mentioning IAEA “GC (XXXIV)/RES/533”:http://www.iaea.org/About/Policy/GC/GC34/GC34Resolutions/English/gc34res-533_en.pdf, which the IAEA General Conference adopted in 1990. The resolution stated that
bq. an armed attack or a threat of armed attack on a *safeguarded nuclear facility, in operation or under construction*, would create a situation in which the United Nations Security Council would have to act immediately in accordance with the provisions of the United Nations Charter;
I find the distinction between a “safeguarded nuclear facility” in the IAEA resolution and “nuclear facilities devoted to peaceful purposes” in the RevCon documents to be an interesting one. I need to learn more about the history there…
The seminal work on this subject is Bennett Ramberg’s 1980 book, “Nuclear Power Plants as Weapons for the Enemy: An Unrecognized Peril” – http://books.google.com/books?id=1TlOBHDKqLgC&pg=PR29&lpg=PR29&dq=bennett+ramberg+nuclear+attack&source=bl&ots=g0vIsf49Bs&sig=l_WCw8qqGRhYfggjV4RiGxHZ9NA&hl=en&sa=X&ei=mruFT7ONI8zzggf5hIHuBw&ved=0CDEQ6AEwAg#v=onepage&q=bennett%20ramberg%20nuclear%20attack&f=false.