In the PUREX process some zirconium, technetium, and other elements are extracted by the tributyl phosphate. Due to the radiation induced degradation of tributyl phosphate the first cycle organic phase is always contaminated with ruthenium (later extracted by dibutyl hydrogen phosphate). Because the very short-lived radioisotopes and the relatively long-lived caesium isotopes are either absent or in low concentrations the shape of the dose rate vs. time graph is different from Chernobyl both for short times and long times after the accident.
In the context of the PUREX process, tributyl phosphate plays a crucial role in extracting zirconium, technetium, and other elements. However, radiation damage to tributyl phosphate leads to contamination with ruthenium, which is later removed by dibutyl hydrogen phosphate. The differing levels of radioactive isotopes result in a unique dose rate vs. time graph compared to Chernobyl for both immediate and prolonged periods following the accident.