Sellafield waste radionuclides in Irish sea intertidal and salt marsh sediments
Sellafield waste radionuclides in Irish sea intertidal and salt marsh sediments
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爱尔兰海潮间带和盐沼沉积物中的塞拉菲尔德废物放射性核素
DOI：
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发表时间：
1993
影响因子：
4.2
通讯作者：
R. Scott
中科院分区：
文献类型：
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作者：
A. B. Mackenzie;R. Scott
到1990年，英格兰西北部塞拉菲尔德核燃料后处理厂排放的低水平液体放射性废物产生了约3×1016Bq的137Cs、6.8×1014Bq的239、240 Pu和8.9×1014Bq的241 Am。239、240 Pu和241 Am的大部分和137Cs的约10%被保留在排泄点附近的细小海洋沉积物中。从1970年代中期到1990年，每年从塞拉菲尔德排放的放射性核素的数量减少了两个数量级，但在此期间，估计临界群体的内部和外部照射减少了不到一个数量级。这表明，在减少排放期间，环境中先前释放的放射性核素继续对临界群体照射作出贡献，并突出了了解控制放射性核素环境分布的过程的必要性。在这方面，受污染的海洋沉积物的再分布可能具有重大意义，特别是如果它导致放射性核素向潮间带地区运输，那里与人类人口接触的可能性相对较大。从若干来源整理了放射性核素浓度和活度比的时间和空间趋势数据，以表明向潮间带地区供应放射性核素的主要机制是受污染的海洋沉积物的再分配。考虑了这种供应机制对临界群体辐射暴露趋势的影响。
Low level liquid radioactive waste discharges from the Sellafield nuclear fuel reprocessing plant in north west England had generated environmental inventories of about 3 × 1016 Bq of137Cs, 6.8 × 1014 Bq of239,240Pu and 8.9 × 1014 Bq of241Am by 1990. Most of the239,240Pu and241Am and about 10% of the137Cs has been retained in a deposit of fine marine sediment close to the discharge point. The quantities of radionuclides discharged annually from Sellafield decreased by two orders of magnitude from the mid-1970s to 1990 but estimated critical group internal and external exposure decreased by less than one order of magnitude over this period. This indicates that during the period of reduced discharges, radionuclides already in the environment from previous releases continued to contribute to the critical group exposure and highlights the need to understand processes controlling the environmental distribution of the radionuclides.Redistribution of the contaminated marine sediment is potentially of major significance in this context, in particular if it results in transport of radionuclides to intertidal areas, where contact with the human population is relatively likely.A review is presented of published work relating to Sellafield waste radionuclides in Irish Sea sediments. Data on temporal and spatial trends in radionuclide concentrations and activity ratios are collated from a number of sources to show that the dominant mechanism of radionuclide supply to intertidal areas is by redistribution of the contaminated marine sediment. The implications of this mechanism of supply for trends in critical group radiation exposure are considered.