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The development of a 222Rn-in-water standard at NPL.

Dean, J C J; Kolkowski, P*; Woods, M J (1997) The development of a 222Rn-in-water standard at NPL. NPL Report. CIRM 5

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Abstract

The design and characterisation of a unit for dispensing 226Ra-free aqueous solutions of 222Rn, with activity concentrations traceable to UK national standards of radioactivity, is described. The unit consists of a polyethylene-encapsulated 226Ra solution immersed in distilled water enclosed within a metal accumulation chamber fitted with a central bellows. The accumulation chamber has metering valves at both ends and is attached to a motor-driven mechanism which serves to contract and expand the bellows. The solution is dispensed via a needle positioned beneath the lower valve. The unit, operated by a Microprocessor Control Unit (MCU), is characterised in terms of the activity concentration of 222Rn dispensed when a specified operating procedure is followed. The unit has been intercompared with a similar system held at the National Institute of Standards and Technology (NIST), Gaithersburg, USA.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CIRM 5
Subjects: Ionising Radiation
Ionising Radiation > Radioactivity
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/707

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