85 Kr, a 10-year half-life krypton isotope, is currently released from reprocessing plants to the atmosphere. There will probably be no urgent need in terms of radiation dose to the local population to retain 83 Kr. However, in view of a worldwide accumulation of 8S Kr in the atmosphere, krypton recovery from reprocessing plants is required or will be required in the near future.

The krypton disposal problem is characterized by the fact that there is no easy way of converting it into a nongaseous form stable at ambient temperature. There are interesting experiments in progress to fix krypton in zeolites by adsorption under high pressure. In England a pilot plant for krypton implantation in metals is under construction. Never­theless, the containment technique presently envisaged for technical use is pressurization in steel bottles.

There are a number of problems in developing efficient krypton-removal processes. The great portion of xenon present in the noble gas fraction tends to solidify at the krypton condensation temperature and to block the equipment. Small fractions of krypton adsorbed in the pretreatment steps may be lost from the main krypton streams. A mechanical problem is presented by the need to exchange steel bottles for krypton collection without significant leakage.

The annual amount of krypton from a 1400 MT/year reprocessing plant is about 500 kg with a 85 Kr activity of about 2 X 107 Ci. This corresponds to 50 standard bottles at 175 atm pressure with a surface dose rate of 400 rem/h. The temperature may be as high as 150°C. The krypton bottles are to be stored in an engineered facility with dry cooling.

There is some consideration of ultimately disposing of these bottles into the sea. This may be well justified because of the relatively short half-life, the low radiotoxicity, and the chemical inertness of 85 Kr. It may even reduce the 85 Kr hazard in comparison with surface storage of high-pressure bottles. At present, however, the London Convention on sea disposal of radioactive waste permits only disposal of solid waste.