Plutonium signatures in refractory fallout support a Chernobyl nuclear jet hypothesis

Measurements of refractory and volatile components in soils from Northern England confirm 244Pu/239Pu consistent with the global average but refractory 240Pu/239Pu significantly higher but consistent with Chernobyl fallout, i.e., 0.390 ± 0.006. Refractory formation suggests temperatures > 3000°C, consistent with atmospheric injection by nuclear-driven explosions rather than by steam or hydrogen. Volatile 240Pu/239Pu is consistent with the global average, 0.181 ± 0.002, and hence lower-temperature formation in the chemical explosions and subsequent fire. This hypothesis is supported by 239Pu fission and capture cross-section enhancement due to the S-wave resonance at ~ 0.3 eV. A further calibration with a 240Pu standard is recommended to substantiate these observations.