Release of 3H and 14C during sampling and speciation in activated concrete

Characterisation of contaminated and activated decommissioning waste require sampling of the studied material for the analysis of different radionuclides. The volatility of 3H and 14C can lead to the loss of the analytes in sampling of solid materials since most often at least some heat is involved in the sampling technique. Especially 3H can be lost in cases when it is present as tritiated water (HTO) due to the evaporation of water even at low temperatures. Therefore, in this study, the 3H and 14C speciations are discussed. Consequently, a drilling sampling technique was developed in order to capture the released 3H and 14C in absorption solutions and measured using liquid scintillation counting. The sampling technique was tested on an activated concrete core. The collected samples were analysed for 3H and 14C (activity concentration and speciation) using a thermal oxidation technique. The results showed that a significant amount of 3H was released during sampling even though the majority of 3H was strongly bound in the activated concrete. The studied activated concrete did not contain measurable amount of 14C and therefore speciation studies were not possible.

Synthesis of the JHPS International Symposium on Tritiated Water

As the decommissioning of Fukushima Daiichi nuclear power plant (NPP) progresses, the issue of how to deal with tritiated water has been attracting attention, both domestically and internationally. This article summarises the live discussion at the International Symposium on Tritiated Water, which was held by the Japan Health Physics Society (JHPS) in June 2020. Two issues – the scientific safety of tritiated water and social consensus building – were covered in the live discussion. The importance of further disclosure and dissemination of information based on steady monitoring was highlighted. It was also pointed out that scientific knowledge and scientific research data are merely the bottom line to achieve social consensus. Through the discussions, it was recognised that the role of JHPS is not only to look at the technical issues of safety, but also to look at social issues from the point of view of radiation protection, and to support the solution of these issues.

Phosphorus Transport in a Lowland Stream Derived from a Tracer Test with 32P

Small streams in urbanized rural areas receive loads of P from various, often episodic, sources. This paper addresses, through a tracer test with 32P, retention and transport of a pulse input of phosphorus in a 2.6 km long stretch of a channelized second-order lowland stream. Tritiated water was introduced alongside the 32P-labelled ortophosphate in order to isolate the influence of the hydrodynamic factors on P behavior. Tracer concentrations in unfiltered water samples were measured by liquid scintillation counting. Four in-stream and five hyporheic breakthrough curves were collected at four points along the stream, two of which encompass a beaver dam impoundment. The overall retention efficiency of 32P along the studied reach was 46%. The transient storage transport model OTIS-P provided reasonable fits for in-stream breakthrough curves (BTCs) but failed at reproducing the hyporheic BTCs. The overall small effect of transient storage on solute transport was higher in the stretch with a more pronounced surface storage. Transient storage and phosphorus retention were not enhanced in the beaver dam impoundment.