What happens to older nuclear weapons when they are upgraded?

[rogerl]

Since nukes are being upgraded every so often, what happens to the older version?

 

[Astronuc]

Since nukes are being upgraded every so often, what happens to the older version?

What kind of nukes - nuclear weapons or nuclear reactors?

 

[rogerl]

What kind of nukes - nuclear weapons or nuclear reactors?

The uranium and plutonium. Older ones have lower yield equal to twice of say Hiroshima explosive power. New nukes have 50 times the power. So what did they do with the older 1 kiloton uranium.. throw it away or recycle it to create 10 kiloton uranium?

 

[Astronuc]

The uranium and plutonium. Older ones have lower yield equal to twice of say Hiroshima explosive power. New nukes have 50 times the power. So what did they do with the older 1 kiloton uranium. throw it away or recycle it to create 10 kiloton uranium?

As far as I know, the old U was down-blended (enrichment reduced) and the material used as fuel in reactors. The US is planning to do the same with the older Pu pits in stock. Russia has a similar program.

http://www.world-nuclear-news.org/WR_Slow_progress_towards_US_use_of_MOX_2102111.html