Speaker
Prof.
Jukka Lehto
(Laboratory of Radiochemistry, University of Helsinki, Finland)
Description
Two inorganic ion exchangers manufactured by Fortum company, Finland, and developed in collaboration with the Laboratory of Radiochemistry, University of Helsinki, have been selected for the radionuclide removal in a new purification system of Energy Solutions, USA, to be commissioned at the Fukushima power plant in 2012. The system will purify approximately 200,000 m3 of highly contaminated effluents obtained due to pumping of sea water into damaged reactors after tsunami had destroyed controlled water circulation in the reactors. The two ion exchangers are CsTreat® for radioactive cesium removal and SrTreat® for radioactive strontium removal. The former is based on a transition metal hexacyanoferrate and the latter on a sodium titanate. These unique ion exchange materials are produced as granules suitable for column use.
CsTreat® and SrTreat® have been utilised in several industrial radionuclide removal processes during the last twenty years [1]. CsTreat® has been in use at Loviisa NPP since 1991 for the decontamination of high-salt (ca. 200 g/L NaNO3/KNO3) evaporator concentrates and about 1,600,000 litres have been purified with only 230 liters of CsTreat® material with a decontamination factor over thousand [2]. Most recent application of CsTreat® took place in the decommissioning of Dounreay Fast Reactors in the UK [3].
The selectivities of CsTreat® and SrTreat® are much higher than that of common organic resins or other radionuclide-selective inorganic materials. For example, the selectivity coefficient of CsTreat® over sodium (kCs/Na) is 1,500,000, which is four orders of magnitude higher than for zeolites and two orders of magnitude higher than for a silicotitanates [4], both of which have been used in the Fukushima waste effluent treatment. As processing capacity for trace level radionuclide removal is mostly governed by the selectivity, CsTreat® can offer superior performance compared to other Cs-selective materials.
REFERENCES
1. J. Lehto and R. Harjula: Selective Separation of Radionuclides from Nuclear Waste Solutions with Inorganic Ion Exchangers, Radiochim. Acta, 86(1999)65.
2. E. Tusa, Successful Cesium Removal Campaign at the Loviisa NPP, Finland, Proceedings of Waste Management 2011, Tucson, AZ, February 27 – March 3, 2011.
3. N.McLean, Disposal of Bulk Sodium Coolant from the Prototype Fast Reactor at the UKAEA Dounreay Site, Scotland, The 10th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM) , September 4-8, 2005, Scottish Exhibition & Conference Centre, Glasgow, Scotland.
4. E. Tusa, R. Harjula and J. Lehto, Use of novel highly selective ion exchange media for minimizing the waste arisings from different NPP and other liquids, Proceedings of Waste Management 2003, Tucson, AZ, February 23-27, 2003
Primary author
Prof.
Jukka Lehto
(Laboratory of Radiochemistry, University of Helsinki, Finland)
Co-authors
Mr
Esko Tusa
(Fortum, Finland)
Dr
Heikki Leinonen
(Carrum Oy, Finland)
Dr
Risto Harjula
(Laboratory of Radiochemistry, University of Helsinki, Finland)
