Unaffected by the radiation of a nuclear explosion

Triskel held up a hand, his auspex scanner in the other. He was glaring at it, his mouth a tight line. ‘Not safe to open the hatch, ma’am. Radiation levels in the red.’
‘Since the other options are get caught by the t’au or just wait to die, I’m afraid we don’t have a choice, Tris.’
‘You need not venture out,’ said one of the Space Marines, his voice so unnaturally deep and resonant compared to Triskel’s and Copley’s. He gestured to his brothers. ‘We will be unharmed. It is we who shall effect the repairs.’

Shadowbreaker