Local and global trace plutonium contributions in fast breeder legacy soils

Area of Science:

• Environmental Science
• Nuclear Chemistry
• Radiochemistry

Background:

• Trace plutonium in the environment originates from both local and global anthropogenic sources.
• Fast-breeder reactors produce plutonium with a distinct isotopic signature, characterized by a reduced 240Pu yield.

Purpose of the Study:

• To estimate the local and global contributions of plutonium in soil at a former fast-breeder reactor site.
• To utilize plutonium isotopic ratios for forensic insights into site-specific activities and inform clean-up strategies.

Main Methods:

• Analysis of plutonium concentration and isotopic ratios (240Pu/239Pu) in soil samples.
• Comparison of on-site plutonium levels with those at undisturbed, distant sites.

Main Results:

• Local and global 239Pu contributions were estimated at 34% ± 1% and 66% ± 3%, respectively.
• Site-derived plutonium exhibited an anomalously low 240Pu/239Pu ratio (0.05 ± 0.04), indicative of fast-neutron breeding.
• Plutonium concentrations were consistent with global fallout levels at undisturbed sites, suggesting localized contamination.

Conclusions:

• Trace plutonium analysis provides valuable forensic information for understanding past activities at nuclear sites.
• The methodology can effectively inform environmental remediation and clean-up strategies for nuclear legacies, particularly from fast-breeder reactors.