During my time in the zone, I never found out about the exact form of activity run in the Jupiter factory after the nuclear disaster in 1986. Before the disaster, the Jupiter factory was a manufacturer of tape recorders, but unlike almost all other places in Pripyat, Jupiter wasn't permanently abandoned after the disaster. As most of the information concerning this factory remain classified, I do not know when the new group of personnel first occupied the premises of this complex, but their work proceeded till 1996.
The secret activities have puzzled me ever since out visit there on the 25th of May this year, as I became aware of the not obvious to find laboratories still full of chemicals, of which some are highly radioactive, and special storage cases for radioactive substances. Today I found out, thanks to Alexandr Rybak, technical director of Pripyat.com that the Jupiter factory became the site for unoffical radiology laboratories dedicated to testing different decontamination techniques and dozimetric equipment.
There have been many theories about the operations in the Jupiter factory after 1986; some of them may be more sensible than others, but currently there seem to be no way to find out the absolute truth.