Annual Variations of ¹⁴C Concentration in the Tree Rings in the Vicinity of Ignalina Nuclear Power Plant

Abstract

In this paper we analyze the radiocarbon (14C) concentration changes over the whole operational period of the Ignalina Nuclear Power Plant (INPP) including the post-shutdown decommissioning. Environmental samples from the vicinity of the INPP and a rural area as background of pine tree rings were analyzed with the single stage accelerator mass spectrometer (SSAMS). The analysis shows the local influence of the INPP from 3 to 7 pMC. The whole time span from 1983 to 2015 is divided into three periods representing the early and late operational and post-shutdown stages of the INPP with different 14C profiles in analyzed samples. The influence of the maintenance of the INPP and radioactive waste management activities are indicated and discussed.

Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania

“…Until 2000, the trend of 14 C specific activity in DIC [ 29 ] coincided with the corresponding year radiocarbon measurement in tree rings, sampled from the P . sylvestris trees in the vicinity of the INPP (see Fig 3 ) [ 27 ].…”

“…However, from 1995 to 1999, the RRA in both factions increased by 540 ± 63 y. In 1998–1999, an increase in 14 C specific activity (up to 10 pMC) was also observed in the tree samples from the vicinity of the INPP [ 27 ] ( Fig 2 ). Enhanced maintenance activities are characteristic for the period 1998–2003.…”

“…Pinus sylvestris (Linnaeus, 1753) ring measurements (samples were collected at a distance of a few kilometers from the INPP) showed an increase in 14 C concentrations by 3–6 pMC during the first 14 years of operation (1983–1997) when no maintenance works of the reactors were needed [ 26 – 28 ]. During the operational period of 1998–2003, increased 14 C specific activity values up to 6–14 pMC coincided with the replacement events of the zirconium alloy tubes of the fuel channels in both units of the INPP [ 27 ]. During the replacement procedure, the reactor graphite stack cavity is opened, and additional 14 CO 2 is expected to be released to the ventilation system of the plant.…”

“…This new information on 14 C excess in the aquatic environment is supplemented by previous measurements of tree rings obtained from P . sylvestris trees in the INPP vicinity and background areas [ 27 ], as well as radiocarbon analysis of DIC [ 29 ].…”

Tracing Carbon Isotope Variations in Lake Sediments Caused by Environmental Factors During the Past Century: A Case Study of Lake Tapeliai, Lithuania

“…RRA 8033 × ln pMC T pMC A ; where pMC A and pMC T is 14 C activity in the aquatic and terrestrial samples of the same period, respectively. As pMC T , we used atmospheric 14 C activity data from OxCal v4.2.4 (Bronk Ramsey 2009;Bronk Ramsey et al 2013) and for the last 20 years 14 C activity data in Scots pine (Pinus sylvestris L.) tree rings, from Ežerinskis et al (2018).…”