That's not actually the water glowing....it's the Chernenko effect from fuel that has been involved in the reaction at power operations.
(new fuel emits mostly alpha). Once it has been placed into service and irradiated, (the fuel is changed out in thirds, currently at 18 to 24 month cycles), it emits beta and a screamer load of gamma. the fuel bundles glow blue after this time.
Interesting side note: if you ever see the "pot" (reactor) glowing blue after ist's emptied, it means there's been "failed" (damaged) fuel and the lower elevations in the building will be all "crapped up" (contaminated). Does NOT make for a happy work environment.
How do I know? Let's just say I once got closely acquainted with a particle of Cobalt60, but "got rid of it" a few days later...Now, I wonder if the guy who pumped my septic system had a nuclear material handler license? [:D]
EDITED TO ADD: The above describes operations in a commercial nuclear generating station, not a naval vessel.