Conversation so far:
Did Mike Gravel have problem with Nuclear bomb ?
he then made a personal appeal to President Nixon to stop the test.
What were his reasons for opposing  it ?
he said the risk of the test was not worth taking.
Did he have problem with the Cold War ?
1971, Gravel sponsored a bill to impose a moratorium on nuclear power plant construction.
Did they pass the Bill ?
CANNOTANSWER.

Question: What else did he do to stop the nuclear plant ?
Self-contained rewrite: What else did Mike Gravel do to stop the nuclear plant besides sponsoring a bill?