This is the 6456th most frequent Russian word.
ядерные
"Nuclear."
In this sentence, 'ядерные' is an adjective describing 'research,' indicating that they pertain to nuclear studies or phenomena.
Ядерные исследования играют важную роль в науке.
Nuclear research plays an important role in science.
Here, 'ядерные' is used to qualify 'technologies,' showing they are related to nuclear energy or applications.
Правительство обсуждает ядерные технологии для энергетики.
The government is discussing nuclear technologies for energy purposes.
In this case, 'ядерные' describes 'reactions,' indicating processes involving atomic nuclei, such as fusion in stars.