Transport of Sellafield-Derived ¹⁴C from the Irish Sea through the North Channel

Abstract

ABSTRACT. Since the early 1950s, the Sellafield nuclear fuel reprocessing plant in Northwest England has released radiocarbon into the Irish Sea in a mainly inorganic form as part of its authorized liquid effluent discharge. In contrast to the trend in which the activities of most radionuclides in the Sellafield liquid effluent have decreased substantially, 14 C discharges have increased since 1994-95. This has largely been due to a policy change favoring marine discharges over atmospheric discharges. 14 C is radiologically important due to its long half life, mobility in the environment, and propensity for entering the food chain. Current models for radionuclide dispersal in the Irish Sea are based on a reversible equilibrium distribution coefficient (k d ), an approach which has been shown to be inadequate for 14 C. Development of predictive models for the fate of Sellafield-derived 14 C requires a thorough understanding of the biogeochemical fluxes between different carbon reservoirs and the processes controlling the net flux of 14 C out of the Irish Sea, through the North Channel. In this study, both an empirical and a halving time approach indicate that close to 100% of the 14 C that is discharged from Sellafield is dispersed beyond the Irish Sea on a time-scale of months in the form of DIC, with little transfer to the PIC, POC, and DOC fractions, indicating that the "dilute and disperse" mechanism is operating satisfactorily. This is consistent with previous research that indicated little transfer of 14 C to Irish Sea sediments. While significant 14 C enhancements have been observed in the biota of the Irish Sea, this observation is not necessarily in conflict with either of the above as the total biomass has to be taken into account in any calculations of 14 C retention within the Irish Sea.

Radiocarbon behaviour in seawater and the brown algae Fucus serratus in the vicinity of the COGEMA La Hague spent fuel reprocessing plant (Goury)—France

“…Although these results are preliminary (a single measurement in POC), it can be noted that this situation has already been observed by other authors Wolstenholme et al, 1998;Megens, 2000;Gulliver et al, 2001). Fig.…”

Sellafield-Derived Anthropogenic 14C in the Marine Intertidal Environment of the NE Irish Sea

“…Where DOC analysis was carried out, the water samples were poisoned with mercuric chloride and stored in the dark at 4 °C prior to analysis. The 4 biogeochemical fractions (PIC, POC, DIC, and DOC) were analyzed according to the methods of Gulliver et al (2001) and Wolstenholme (1999).…”

Temporal Trend in the Transfer of Sellafield-Derived 14C into Different Size Fractions of the Carbonate Component of NE Irish Sea Sediment

“…Thus, its behavior cannot be described by a sorption coefficient (K d ). Ultimately, a Figure 3 137 Cs and 14 C aquatic discharges from Sellafield (1952Sellafield ( -2012 proportion of the 14 C is deposited either directly or indirectly, as organic carbon or carbonates, into a mixed-age sediment pool Cook et al 1995Cook et al , 2004bWolstenholme et al 1998;Gulliver et al 2001;MacKenzie et al 2004). 14 C contributes only 4.2% to the current total dose rate received by critical consumer groups of marine fish and shellfish from the Cumbrian coast; nevertheless, due to its long half-life (5730 yr), ready entry into the food chain, and high environmental mobility, the aqueous 14 C discharges from Sellafield are the major contributor to the collective dose commitment to UK and European populations from the entire nuclear industry (BNFL 2002).…”