[en] A new radionuclide generator system has been developed and demonstrated for the production of ²¹²Bi from ²²⁴Ra/²¹²Pb and for ⁹⁰Y from ⁹⁰Sr. The new concept, called a Multicolumn Selectivity Inversion Generator, involves the selective retention of the desired daughter radionuclide from a solution of the parent or parents by a primary separation column followed by stripping the daughter radionuclide from the primary column, and immediately without feed adjustment, passing the daughter through a secondary separation (guard) column that retains the parents while the daughter elutes unrestrained. The new generator system minimises the effects of radiation damage to the support material permitting the reliable production of nuclides of high chemical and radionuclidic purity. (author)