Mururoa’s silent witnesses
Forty-six years ago today Gisborne man Tony Coutts was a “10-foot tall and bulletproof” 19-year-old when he sailed on HMNZS Otago for the nuclear bomb test zone at Mururoa.
France had conducted atmospheric nuclear tests at Mururoa, an atoll 1250 kilometres south-east of Tahiti, since 1966.
Sent under orders from the Government to protest the atmospheric testing of nuclear weapons by the French, the Otago sailed out on June 28, 1973.
Mr Coutts and a few other Gisborne and East Coast men were among the 242 crewmen told by Prime Minister Norman Kirk their mission would “ensure that the eyes of the world are riveted on Mururoa”.
They were to be “silent witness(es) with the power to bring alive the conscience of the world”.
Prior to departure the ship’s company was offered the chance to opt out of sailing with the Otago — 22 took up the offer, 10 for personal reasons and 12 for family reasons.
No officers or specialist tradesmen opted out, including Mr Coutts, who was a radio technician on the ship.
The ship’s crew undertook NBCD (nuclear, biological, and chemical defence) exercises every day.
As Otago approached the territorial limits, crew saw a balloon with the nuclear trigger device slung beneath it. Otago released wind-direction balloons which were tracked by fire-control radar to measure patterns of fallout.
“We had personal indicators hung around our necks 24 hours a day. The indicators were to detect radioactivity in the air,” says Mr Coutts.
Before the nuclear device was detonated the entire crew of the Otago — apart from navigation officer Commander Tyrrell, the yeoman of signals and two reporters equipped with anti-flash gear and dark goggles while posted on the bridge — were sent below decks.
At 8am the next day the French detonated a device suspended by balloon 2000 feet above the atoll. The device was not a nuclear bomb but a nuclear trigger — a fission bomb that causes atomic and chemical reactions that increase the yield of the hydrogen bomb.
“Otago was 21.5 miles west of the detonation,” says an online Navy Museum document.
“The flash was intense enough that the crew inside the ship’s citadel saw it come through the ventilation system. The yield was estimated to be 5.4 kilotons.”
“We were all closed up when the bomb went off,” said Mr Coutts. “It was only a triggering device. The ship didn’t shudder or anything. Two or three minutes later we were allowed back on deck to take pictures.”
The mushroom cloud was in full bloom.
The sensors Mr Coutts helped install on parts of the Otago such as the mast, bridge and quarterdeck did not detect any radiation and the vessel was not affected by any fallout or other contamination from the explosion.
“Those of us on the Otago were upwind from the explosion. We were replaced by the Canterbury. When the bomb went off they were downwind.”
Otago’s crew, however drank desalinated seawater. The water was distilled but the process did not filter out radioactive contamination.
Results from the crew’s personal indicators and meters had been lost since the tests, said Mr Coutts.
“When we got back from Mururoa, at the airport Dave Bain and I were on the plane. My mother picked us up from the airport. The press wanted a story but my mother told them in no uncertain terms to go away.”