It is a common belief that radioactive decay rates are unchanged by external conditions, despite many examples of small shifts (particularly involving external pressure and K-capture decays) being well documented and understood. However, Fabio Cardone of the Institute per lo Studio dei Materiali Nanostrutturati in Rome and colleagues have shown a dramatic increase – by a factor of 10,000 – in the decay rate of thorium-228 in water as a result of ultrasonic cavitation. Exactly what the physics is and whether or not this sort of effect can be scaled up into a technology for nuclear waste treatment remain open issues.

Further reading

F Cardone, R Mignani and A Petrucci 2009 Phys. Lett. A 373 1956.