> was a “nukie” when he enlisted. Dumb as a box of rocks
Not sure what time period this took place, but if you're referring to the US Navy Nukes, then about ~20 years ago Nukes needed a high ASVAB score 95+ (top 5% of test takers) I think it's a bit lower now--and there are other test they can combine scores with--since they all leave for high paying jobs after their enlistment ends. The standard now may not be what it was for simply being a Nuke; but to also be a Submariner (volunteer position), he would have also had to learn all of the submarine systems (mechanical, electrical, navigation, weapons, safety etc) and then a board of senior submariners decide if he was proficient enough to serve on a submarine. You may be being a little harsh calling your BIL "Dumb as a box of rocks", if he accomplished all that.
Not sure what time period this took place, but if you're referring to the US Navy Nukes, then about ~20 years ago Nukes needed a high ASVAB score 95+ (top 5% of test takers) I think it's a bit lower now--and there are other test they can combine scores with--since they all leave for high paying jobs after their enlistment ends. The standard now may not be what it was for simply being a Nuke; but to also be a Submariner (volunteer position), he would have also had to learn all of the submarine systems (mechanical, electrical, navigation, weapons, safety etc) and then a board of senior submariners decide if he was proficient enough to serve on a submarine. You may be being a little harsh calling your BIL "Dumb as a box of rocks", if he accomplished all that.