Radioactive waste in Lyttelton Harbour remains unchecked
“Radio-active waste dumped at sea” read a headline in The Press in 1963.
The story had been shuffled back to page 12 as it was, according to a science history expert, not entirely out of place to dump radioactive material off the coast of New Zealand.
At times just 18 metres below the surface, radioactive waste from 70 years ago still sits encased in concrete, steel drums and a wooden box, on the ocean floors around Lyttelton Harbour or the Cook Strait.
There are more than 13 recorded incidents of radioactive material being dumped into the ocean in the country’s history, with everything from contaminated medical equipment to radium ending up at the bottom of the sea.
The sites, however, are unmonitored, with one government agency saying they’re not considered hazardous to human or marine life.
Victoria University of Wellington Science in Society professor Rebecca Priestley, who wrote the book on Aotearoa’s history with nuclear science, explains that while the country never had nuclear power, radioactive isotopes were used elsewhere.
In the 1950s and early 1960s contaminated medical equipment such as hardware, glassware, cotton wool and boxes used to store radioactive material ended up in Lyttelton Heads, in water 18m deep.
These were stored in drums, barrels and a wooden box, a 1999 report by the International Atomic Energy Agency showed.
Between 1961 and 1976 there were a further 13 disposals of radioactive waste into the ocean, split between two locations off the coast of Wellington. While these disposals also involved contaminated equipment, this time radioactive sources were dumped too.
Caesium 137, cobalt 60, radium 226, strontium 90 and americium 241 were encased in concrete and sent to the sea floor.
For the most part the disposals were done by boat, but during one instance the material was dropped out of an aircraft by Cape Palliser.
Priestley said the National Radiation Library, which dumped the material, had to consult first with the maritime authority to find a suitable location.
The radioactive isotopes were sealed in a protective capsule, before being embedded in concrete within 20-litre steel drums, she said.
“It was absolutely the done thing for awhile.”
It wasn’t seen as controversial as the waste New Zealand dumped was nothing compared to what was happening in the Northern Hemisphere, she said, in countries with nuclear power industries.
Attitudes didn’t start to shift until around 1972, when there was a global convention to protect the marine environment from human activities, Priestley said.
The ‘Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter’, known in short as the “London Convention’, prohibited the dumping of high level radioactive waste in the ocean.
“It still permitted low level radioactive waste to be dumped – but now special permits were required, and there were specific monitoring requirements.”
Only one dumping happened in New Zealand after these rules were adopted, in 1976, when a special dumping permit was obtained.
The rules changed again in 1983, when everyone who signed the original London Convention agreed to stop dumping even low level radioactive waste in the ocean.
Since then, Priestley said, waste has been stored in the National Radiation Laboratory in Christchurch.
A Ministry of Health spokesperson said they had monitored levels of radiation in New Zealand and the Pacific since 1960, but that it was unrelated to the dumping of radioactive waste from New Zealand sources.
“It is intended to monitor for elevated radiation levels following nuclear weapons testing in the pacific.”
New Zealand’s disposals were in line with actions taken by similar countries at the time, they said.
“Any material leaking from the packages would quickly fall below the background levels from natural occurrence and nuclear fallout from weapons testing.”
Now, radioactive waste is kept at the National Store – the details of which are not made public for security reasons, the spokesperson said.
The details they could release were that the amount of waste generated had remained steady for the past few decades and that there is still sufficient space in it.
Every year the health ministry and ESR take seawater samples from Lyttelton Harbour and look for the presence of artificial nuclides – an indicator for the presence of radioactive waste.
In the 2022/2023 report, no artificial gamma emitters were detected, the report showed.
In 1976 the United States transported 101 packages of soil, contaminated by a nuclear power plant, through Lyttelton from Antarctica.