The British Government offered to help New Zealand build a small nuclear reactor, declassified government papers reveal.
The papers show New Zealand began exploring the possibility of building a small graphite pile reactor in the mid 1940s, as one of a series of nuclear plants being built by Commonwealth countries.
Canada and Australia were considering large-scale plants for energy generation, but New Zealand was more interested in a smaller facility to generate isotopes for medical, industrial and scientific purposes.
New Zealand was considered to have largely untapped sources of hydro-electricity, which would render a nuclear power plant unnecessary for at least 20 years.
Because of the short half-life of many useful radioactive isotopes they could not be shipped to New Zealand, hence having a small reactor in the country was considered desirable.
The Department of Scientific and Industrial Research was an enthusiastic proponent of the scheme and a report from DSIR founding secretary Ernest Marsden to Secretary of the Cabinet Foss Shanahan extolled the virtues.
"New Zealand is coming of age and must be prepared to take a part in everything that is worthy in progress of civilisation," Dr Marsden wrote.
Charles Watson Munro, a leading New Zealand nuclear scientist who worked at Chalk River, Canada, and at Harwell, England, from 1944 to 1948 and was about to return home, said a small graphite pile would enable New Zealand, at a comparatively small cost, to have available the nucleus for an atomic research project.
The pile would also supply an ample supply of radioactive material for industrial and agricultural purposes.
However, Prime Minister Peter Fraser was far from convinced. In a memo to his deputy, Walter Nash, and Cabinet minister Terence McCoombs, Fraser wrote that "the only justification I can see for this would be in regard to the preparation of certain radioactive elements used for medical treatment".
With no sources of uranium in New Zealand - although the papers reveal the Government also approved prospecting for the element - radioactive material for the pile would have had to be imported from Canada or Britain.
The New Zealand Government wrote to British Prime Minister Clement Attlee in 1948 asking whether it was regarded as being in the Commonwealth's interest for a reactor to be built here.
"I am glad to assure you that in my opinion there would be an advantage to the Commonwealth in the development by the New Zealand Government in this project," Mr Attlee wrote to Mr Fraser.
Britain, Mr Attlee added, would be happy to offer its assistance.
That letter is the final document in the file, leaving the question of why the reactor never went ahead hanging tantalisingly unanswered.
Today, all New Zealand's radioactive material is imported, either from Britain or from the Lucas Heights reactor in Sydney.
The Institute of Geological and Nuclear Sciences owns and operates the isotope centre in Lower Hutt, which provides a wide range of isotope-based services.