[Tango589]

I've found the key to repairing faulty reactors is to surface the boat, SCRAM the faulty reactor if required, close all vents apart from the reactor room (in the misc. systems panel), purge the ventilation (removing radiation from the reactor room without spreading it round the boat) until the radiation reaches an acceptable level, get a strong engineer suited and booted with a toolbox, gloves, gas mask and radiation suit and set him to work. Hopefully with the reduced radiation levels, he won't absorb too much before the work is done.