...he built a small nuclear REACTOR
in the shed...
The Big Bang Theory Season 1, Episode 4
Luckily for you,
this is not a nuclear REACTOR.
The Big Bang Theory Season 1, Episode 16
It was already targeted
to poke around a nuclear REACTOR in Siberia.
The Big Bang Theory Season 2, Episode 7
...and tried to build
a nuclear REACTOR in the tool shed.
The Big Bang Theory Season 8, Episode 23