Radiocarbon Impact on a Nearby Tree of a Light-Water VVER-Type Nuclear Power Plant, Paks, Hungary

R Janovics,I Barnabás,Z Kern,L Wacker,M Molnár,D Güttler

doi:10.1017/s0033822200057982

Abstract

Tree-ring series were collected for radiocarbon analyses from the vicinity of Paks nuclear power plant (NPP) and a background area (Dunaföldvár) for a 10-yr period (2000–2009). Samples of holocellulose were prepared from the wood and converted to graphite for accelerator mass spectrometry (AMS) 14C measurement using the MICADAS at ETH Zürich. The 14C concentration data from these tree rings was compared to the background tree rings for each year. The global decreasing trend of atmospheric 14C activity concentration was observed in the annual tree rings both in the background area and in the area of the NPP. As an average of the past 10 yr, the excess 14C emitted by the pressurized-water reactor (PWR) NPP to the atmosphere shows only a slight systematic excess (∼6′) 14C in the annual rings. The highest 14C excess was 13′ (in 2006); however, years with the same 14C level as the background were quite frequent in the tree-ring series.

Highlights

Trees intake carbon mostly from atmospheric CO2 uptake via photosynthesis
Samples of holocellulose were prepared from the wood and converted to graphite for accelerator mass spectrometry (AMS) 14C measurement using the MICADAS at ETH Zürich
The 14C concentrations of tree rings sampled near Paks nuclear power plant (NPP) exceed those from the background station in most cases; this difference is small

Summary

Introduction

Trees intake carbon mostly from atmospheric CO2 uptake via photosynthesis. The actual radiocarbon isotope ratio of the surrounding air is preserved in their organic materials (Levin et al 1985). Changes in the atmospheric 14C activity concentration are preserved in the cellulose of tree rings (Tans et al 1979; Otlet et al 1989; Isogai et al 2002; Mazeika et al 2008). 14C emitted during the operation of nuclear facilities may increase the 14C content of the local atmosphere. The Paks nuclear power plant (NPP) has been operating with VVER-440/213 type reactors since 1987. VVER-type nuclear power plants emit 14C in the form of CO2 and hydrocarbons. Several atmospheric 14C samplers have been installed to monitor the air around the NPP and Interim Spent Fuel Storage Facility (ISFSF). There was a serious third-level incident (INES-3, on the basis of International Nuclear and Radiological Event Scale [INES]) on 10 April 2003 in Unit 2 of the Paks NPP. The aim of our research is to determine whether the effect of the incident can be detected in the nearby vegetation during normal operation intervals and after the malfunction period in 2003

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Conclusion