Evaluation of chronometers in plutonium age determination for nuclear forensics: What if the ‘Pu/U clocks’ do not match?

This article discusses the age dating results of plutonium/uranium chronometers with a focus on the consequences for age plutonium determination when the basic assumptions of the methodology are not fully met: Incomplete removal of the daughter nuclides at the production date and uranium contamination of plutonium samples. In addition to the 238Pu/234U, 239Pu/235U and 240Pu/236U, the 242Pu/238U chronometer is discussed. The 242Pu/238U radiochronometer has only scarcely been used, due to its high sensitivity to residual uranium. However, it can be a very useful indicator for uranium contamination of aged plutonium samples.