Retrospective Search for Evidence of the 1957 Windscale Fire in NE Ireland Using ¹²⁹I and Other Long-Lived Nuclides

Abstract

The accident at Windscale in October 1957 resulted in the release to the atmosphere of a large quantity of radioactivity. The presented work is a retrospective search for evidence of contamination from the accident in the northeastern region of Ireland. A lake yielding a high-resolution sedimentary record was identified near the northeast coast of Ireland. This site was used to reconstruct the history of radionuclide input to the region, based on the analysis of a set of cores extracted from the lake. A chronology for sediment accumulation within the lake was established using radioisotopic dating techniques (including 270Pb). High-resolution gamma and alpha spectrometry techniques were used to quantify concentrations of 137Cs, 239,240Pu and 241Am, all of which were released during the accident. The primary radioactive component of the release was 131I (T1/2 = 8 days), but this short-lived isotope has long since decayed. However, 129I (T1/2 = 1.57 x 10(7) years) was also released during the accident, and in a known ratio to 131I. Recent advances in accelerator mass spectrometry now make it feasible to measure 129I at ultra-trace level and thereby retrospectively reconstruct 131I deposition. Clearly resolved concentration profiles for 137Cs, 239,240Pu and 241Am in the lake cores reflect known historical fallout trends. The data suggest that any contamination from the Windscale fire that might have reached this catchment has been overwritten by input from the testing of nuclear weapons in the atmosphere. A time-series for 129I in lake sediment shows that concentrations in recent sediments are approximately 10 times greater than concentrations recorded in strata corresponding to the period of maximum fallout of other radionuclides from atmospheric testing of nuclear weapons (1964). These recent increases in 129I are attributed to increased emissions from the nuclear industry. The study yields no evidence of any enhancement in radioisotope concentrations, over and above global fallout, in strata dated to 1957, and we conclude that contamination from the Windscale fire had negligible impact on the northeastern region of Ireland.

Tracing anthropogenic nuclear activity with 129I in lake sediment

“…Comparison of our 129 I data with those pattern found in sediment from Lake Ballywillan (Gallagher et al, 2005), for the period 1950e1995, and the profile in the Fiescherhorn glacier (Reithmeier et al, 2006), for the period 1970e 2002, shows rather different patterns (Fig. 6).…”

“…However, we see this downward migration of 129 I to have insignificant effects on the huge fallout related signals obtained in the sediment. (Gallagher et al, 2005), (b) ice from Fiescherhorn glacier, Switzerland (Reithmeier et al, 2006) and (c) this study.…”

“…This potential has recently been explored in sediments from Lake Ballywillan in NE Ireland, in order to trace 129 I released by the Windscale (presently the Sellafield facility) accident in 1957, which was associated with a relatively large scale release of radioactive smoke from a fire within the graphite-moderated reactor (Gallagher et al, 2005). However, releases from National Institute for Standards and Technology (NIST).…”

Pre- and post-Chernobyl accident levels of 129I and 137Cs in the Southern Baltic Sea by brown seaweed Fucus vesiculosus

“…129 I has also been produced anthropogenically during the last 60 years during fission processes associated with civil and military nuclear activities and accidents, such as the Chernobyl accident (April 26th, 1986). An estimated 50e150 kg of 129 I was released to the atmosphere during the main period (1945e1964) of nuclear weapons testing (Raisbeck et al, 1995;Wagner et al, 1996) and a further w6 kg were released due to the Chernobyl accident (Gallagher et al, 2005). However, the main sources of anthropogenic 129 I are nuclear fuel reprocessing plants (La Hague-France and SellafieldEngland, see Fig.…”

Analysis of ¹²⁹I and its Application as Environmental Tracer

“…Analysis of the sediment core can be used to retrieve deposits/events in the past. The distributions of 129 I in marine sediment cores collected in Kattegat [54] and in lake sediment collected from Sweden [41,55] and UK [56] have been reported. Fig.…”