Why hasn't New Zealand's uranium supply ever been commercially mined?

Source: Seven Sharp

It's a little-known fact that New Zealand has a supply of uranium, an ore mineral which is used for nuclear power plants and nuclear weapons.

With the high price of uranium and various prospector rushes on it throughout the decades since it was first discovered in New Zealand, the question arises as to why haven't we exploited this resource?

TVNZ1's Seven Sharp reporter Julian Lee headed off to the South Island's Tasman region in search of mineral riches.

He discovered there is uranium there, but not in big enough doses to make extracting it commercially viable.