Hi Mary,
While it seems a bit of a setback, your husband's symptoms should subside over the next few weeks.
I had SRT (admittedly only 20 fractions) two years ago and I regained control of my bladder relatively quickly. I do however still occasionally get the sudden urge to pee, but I manage this quite easily by clenching my pelvic floor for a few seconds until the urge goes. Half an hour later I'll go to the toilet as normal.
Hopefully this goes some way to reassure you.
Kev.