A complement of 140 men is too much for a merchant vessel, so she should be a naval one, not too big; maybe a corvette or some kind of aux. vessel.
Maybe a Flower Class of the "French" series, used as target for Bikini experiment?
I thought the Marshall Islands tests were conducted on US ships ( with
one captured Japanese warship ), some 90 ships, all told; and the
morality ( or rather the lack of it ) in keeping men in the area, and
even worse to make them return to contaminated ships is one
of the most appalling incidents in history. Sorry, I know this is a
quiz, but man's inhumanity towards his fellow needs to be revised
Anyway Ronnie .... is this the right area for us to be looking??