Impressive and heartfelt.

(Director Bigelow) piles up one nerve-racking crisis after another, interspersed with moments of ethereal, almost otherworldly beauty.

There is one surprise in the movie, a decision having nothing to do with the reactor, that depends entirely on the ability of the characters to act convincingly under enormous pressure; casting stars of roughly equal weight helps it to work.

The movie gradually works its way, with quiet intelligence and apparent conviction, until there's no turning from it. An hour in, and we're on that boat.

Bigelow gives this film edge, tension and something you aren't expecting: a woman's touch for teasing out the buried emotion beneath those stoic surfaces.