Nuclear Test, Nuclear Bomb Test, Nuclear Testing
noun
A nucleus experiment (実験) is a nuclear test.
かくじっけん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
予算の都合上、核実験への臨時スタッフの採用は増やせない。
Budget-wise, we are unable to increase our temporary staff for nuclear testing.