question: When did the reactor that has a rated power of 945 MW and ended construction on May 10, 1978 close?
answer: SELECT close_of_reactor FROM table_name_13 WHERE rated_power = "945 mw" AND finish_construction = "may 10, 1978"
context: CREATE TABLE table_name_13 (close_of_reactor VARCHAR, rated_power VARCHAR, finish_construction VARCHAR)