Changes to the UK National Primary Standards of Air Kerma and Absorbed Dose Incorporating ICRU Report 90 Recommendations

Changes to the UK national primary standards of air kerma and absorbed dose will take effect from 1st of September 2019. The changes are due to (i) the UK adoption of the recommendations of the International Commission on Radiation Units and Measurements Report No. 90 and (ii) the recent introduction of new or re-evaluated primary standards as part of NPL's ongoing programme of research and development. This report summarises the total changes to the primary standards and the resulting effect on the calibration coefficients of secondary standard ionisation chambers calibrated at NPL.