It's a trip over 50 years in the making. Two New Zealand frigates were sent to the Pacific to observe and protest French nuclear testing at Mururoa Atoll in 1973, exposing 500 sailors to radiation. On the way back one of those vessels, the HMNZS Canterbury, was invited to Rarotongo, but the ship's captain decided to head home instead. Now, 19 veterans from the tests are finally heading to the Cook Islands for one last tour of duty together. Jimm…