Measurement of Ho-166 specific activity under nuclear decay data

Project Description

Each participant will develop new primary activity standards of Ho-166 and will measure the decay data of their new primary activity standards of Ho-166 using nuclear spectrometry.

Final Report 2022-10-20

The comparison has been completed and results are available in the KCDB.

Progress Report 2022-01-22

CMI, LNE-LNHB and NPL standardised the 166Ho solutions using primary activity measurements techniques. ENEA standardised the solution by a relative method using an ionization chamber calibrated later by a primary technique using another 166Ho solution provided by another manufacturer. The results reported by the participants were analysed and evaluated using the power-moderated mean method. All reported results would be accepted by the method for the KCRV, however, the value reported by ENEA was not included in the KCRV because it was not coming from the primary measurement method. The KCRV of this comparison is determined to 1 December 2017 00:00 UTC using the 166Ho half-life of (26.809 ± 0.014) h. The Draft B is ready (21 Jan 2022) and is going to be provided to CCRI(II) for review.

Progress Report 2020-02-20

NPL, CEA and CMI already submitted the results. ENEA needed an additional Ho-166 solution to confirm original measurements (which were not performed with a primary standardisation method and therefore the uncertainty is higher), but it had long-lasting problems with ordering and delivering a new Ho-166 solution. Eventually, ENEA decided to produce Ho-166 in TRIGA reactor close to Rome. Ho-166 solution was finally produced at the end of October 2019 (an amount of about 750 MBq in 15 mL of Ho-166 in liquid form, with the same chemical composition provided on December 2017 by CMI) and subsequently used for confirmation measurements. ENEA has analysed the recorded data between December 2019 and February 2020. ENEA's final results should be delivered shortly. When CMI gets the confirmation that ENEA finalised the reporting form, CMI will collect the participants results and start to work on the report to conclude the comparison.