A NEW METHOD FOR MEASUREMENT OF BI-210 ON GLASS SHEETS, TO ESTIMATE RETROSPECTIVE RADON EXPOSURE

In 1992 a living area was discovered in Hungary where the radon exhala tion rate was extremely high. One of the questions asked was whether t his level of concentration has existed for a long time. Because radon daughters are continuously embedded on the surface of glass sheets by alpha recoil, it means that old glass sheets can 'remember' past radon concentration levels via long-lived decay products. Traditionally Po- 210 (daughter of Bi-210) surface activity concentration is measured wi th an ionisation chamber or solid state nuclear track detectors (SSNTD ). A new and fast radiochemical method has been developed to investiga te surface beta activity concentration of Bi-210, The new method was c hecked by comparing it with SSNTD. It is concluded that the radon conc entrations in the radon prone area where the glass samples were analys ed have not changed by more than a factor of two over the last 8-55 ye ars.