PROFICIENCY TEST OF THE SSDL-ININ-MEXICO FOR THE CALIBRATION OF WELL-TYPE CHAMBERS WITH HDR 192IR SOURCES USING TWO DIFFERENT DOSIMETRY CODES OF PRACTICE FOR THE DETERMINATION OF REFERENCE AIR KERMA RATE KR.

The results of the comparison between SSDL-ININ and SSDL-CPHR (pilot laboratory) demonstrates the competence of the SSDL-ININ for the performance of the KR in 192Ir. The RININ/CHPR ratio for the calibration coefficients is 0.989 ± 0.005. The comparison uses three SI-HDR 1000-Plus as transfer chambers, series: A02423, A941755 and A973052. CPHR used a secondary standard PTW 3304 chamber, s/n 154, calibrated at PTB and ININ employed a secondary standard SI-90008 s/n A963391, calibrated at NPL. To determine KR, the SSDL-CPHR used the IAEA TEC-DOC-1274 and the SSDL-ININ used the IPEM (UK) code of practice. The latter uses a correction factor by source's geometry, ksg. The results show that both codes are equivalent; however, for the use of well chambers in the highlands or in locations with reduced atmospheric pressure, it is needed to apply an additional factor k'P, or, to design a well chamber with air-equivalent walls for the application of the conventional kPT.