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A retrospective search for evidence of the 1957 Windscale fire in NE Ireland using 129I
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
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2005 (English)In: Environmental Science and Technology, ISSN 0013-936X, Vol. 39, no 9, 2927-2935 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2005. Vol. 39, no 9, 2927-2935 p.
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-92489OAI: oai:DiVA.org:uu-92489DiVA: diva2:165591
Available from: 2004-12-20 Created: 2004-12-20 Last updated: 2009-10-02Bibliographically approved
In thesis
1. Accelerator Mass Spectrometry of 36Cl and 129I: Analytical Aspects and Applications
Open this publication in new window or tab >>Accelerator Mass Spectrometry of 36Cl and 129I: Analytical Aspects and Applications
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two long-lived halogen radionuclides (36Cl, T1/2 = 301 kyr, and 129I, T1/2 = 15.7 Myr) have been studied by means of Accelerator Mass Spectrometry (AMS) at the Uppsala Tandem Laboratory.

The 36Cl measurements in natural samples using a medium-sized tandem accelerator (~1 MeV/amu) have been considered. A gas-filled magnetic spectrometer (GFM) was proposed for the separation of 36Cl from its isobar, 36S. Semi-empirical Monte-Carlo ion optical calculations were conducted to define optimal conditions for separating 36Cl and 36S. A 180° GFM was constructed and installed at the dedicated AMS beam line.

129I has been measured in waters from the Arctic and North Atlantic Oceans. Most of the 129I currently present in the Earth's surface environment can be traced back to liquid and gaseous releases from the nuclear reprocessing facilities at Sellafield (UK) and La Hague (France). The anthropogenic 129I inventory in the central Arctic Ocean was found to increase proportionally to the integrated 129I releases from these reprocessing facilities. The interaction and origin of water masses in the region have been clearly distinguished with the help of 129I labeling. Predictions based on a compartment model calculation showed that the Atlantic Ocean and deep Arctic Ocean are the major sinks for the reprocessed 129I.

The variability in 129I concentration measured in seawater along a transect from the Baltic Sea to the North Atlantic suggests strong enrichment in the Skagerrak–Kattegat basin. The 129I inventory in the Baltic and Bothnian Seas is equal to ~0.3% of the total liquid releases from the reprocessing facilities.

A lake sediment core sampled in northeastern Ireland was analyzed for 129I to study the history of the Sellafield releases, in particular the nuclear accident of 1957. High 129I concentration was observed corresponding to 1990 and later, while no indication of the accident was found.

The results of this thesis research clearly demonstrate the uniqueness and future potential of

129I as a tracer of processes in both marine and continental archives.

81 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1
Environmental technology, Accelerator Mass Spectrometry, iodine-129, chlorine-36, gas-filled magnet, radioactive tracer, Arctic Ocean, Nordic Seas, North Atlantic, thermohaline circulation, Sellafield, La Hague, Miljöteknik
National Category
Other Environmental Engineering
urn:nbn:se:uu:diva-4725 (URN)91-554-6124-7 (ISBN)
Public defence
2005-01-21, Häggsalen, The Ångström Laboratory, Lägerhyddsv. 1, Uppsala, 10:15 (English)
Available from: 2004-12-20 Created: 2004-12-20 Last updated: 2009-03-26Bibliographically approved

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