Wayne O'Donnell was a stoker in the engine room of HMNZS Canterbury in August 1973 when it witnessed a nuclear test at Mururoa Atoll.
Now aged 60, the Hastings businessman has cancerous lumps on the back, shoulder and top of his head but it's the health of his descendants that worries him.
"Within 30 seconds of the blast we were allowed on deck to observe the cloud.
"We saw the cloud - it was an obvious nuclear blast cloud. It was like a mushroom with the stalk.
"After the detonation burst, we zig-zagged and, because of the French miscalculating where the cloud was going, we ended up sailing through it twice.