76454
The plutonium-238 used in these RTGs has a half-life of 87.74 years , in contrast to the 24,110 year half-life of plutonium-239 used in nuclear weapons and reactors .
 half-life
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
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Text: {0} 
Answer:
 half-life