A friend of mine was killed in the accident so I followed events closely. I spoke to an ex NAPO engineer (also now dead, unfortunately) who was there at the time and he confirmed the story. I believe it occured in 1988.
There is evidence of this, and far more damning occurances attributed to the same person in the minutes and statements of the BoI. I was following it at the time and am not sure if they are still available online. I will search and get back to you.
I don't know if the statements are still there, but this is the site
Australian Government, Department of Defence