Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.
J Radiol Prot. 2021 Jun 1;41(2). doi: 10.1088/1361-6498/abf902.
This paper reports on a detailed investigation into the disposal procedures and records from the operational period (1960-1968) of the Little Forest Legacy Site (LFLS) in eastern Australia. The aims of the paper are firstly, to highlight the priority issues which are relevant to the radiological assessment of the LFLS, and secondly, to present key lessons that may help to guide future investigations of the records at similar sites. Particular effort was put into assessing the various types of relevant documents and the relationships between them. A specific objective of this work was to evaluate an inventory of the wastes which was reported shortly after the time of disposals. A major finding of the study is that the original actinide inventory for LFLS relied solely on estimates from a limited number of specific records known as 'Scrap Disposal Reports' (SDRs). For example, the estimated amount of plutonium disposed at the LFLS was based on only seven SDR records. Given that there are approximately 50000 buried items, it is possible that other Pu-contaminated items could make a significant additional contribution to the amount of Pu present at the site. For some waste components (e.g. beryllium) the documentation shows that rough estimates of disposal quantities were made, based on the number of disposed Be-contaminated items in each trench. The use of such approximations casts some doubt on the accuracy of the previous inventory of wastes at the site. In addition, the early summaries of radionuclide disposals, which categorized radionuclides into groups according to their radiological hazard, contained significant underestimates of the radionuclide inventory in the most hazardous category (referred to at the time as 'Group I' radionuclides). This was mainly due to the omission of the Pu (which had been recorded on the SDRs) from the Group I inventory, but was also in part because the Group I radionuclide content of disposed sludge drums (from a wastewater treatment plant) was not taken into account for most of the disposal period. Establishing the disposal history and radionuclide inventory at legacy sites is an important pre-requisite to evaluating their radiological impact and developing management options. The detailed investigation of the LFLS records shows the importance of understanding the operational practices of the period and the derivation of the original inventories. These insights should help guide future efforts to better understand disposal histories and inventories at LFLS and elsewhere.
本文报告了对澳大利亚东部小森林遗产遗址（LFLS）运营期间（1960-1968 年）的处置程序和记录进行的详细调查。本文的目的首先是强调与 LFLS 放射性评估相关的优先问题，其次是提出可能有助于指导类似遗址记录未来调查的关键经验教训。特别努力评估了各种类型的相关文件及其之间的关系。这项工作的一个具体目标是评估处置后不久报告的废物清单。该研究的一个主要发现是，LFLS 的原始锕系元素清单仅依赖于有限数量的特定记录，即“废料处置报告”（SDR）的估计。例如，LFLS 处置的钚估计量仅基于七个 SDR 记录。鉴于有大约 50000 个掩埋物品，其他可能含有 Pu 的物品可能会对现场 Pu 的含量产生重大的额外贡献。对于某些废物成分（例如铍），文件表明，根据每个沟渠中处理的受 Be 污染物品的数量，对处理数量进行了粗略估计。这种近似值的使用对现场废物的先前清单的准确性产生了一些怀疑。此外，根据放射性危害对放射性核素进行分类的早期放射性核素处置摘要，对最危险类别（当时称为“第一组”放射性核素）的放射性核素清单存在重大低估。这主要是由于 Pu（已记录在 SDR 上）未包含在第一组清单中，但部分原因是在处置期间的大部分时间里，未考虑到来自废水处理厂的处置污泥桶的第一组放射性核素含量。在评估其放射性影响并制定管理方案之前，确定遗留场址的处置历史和放射性核素清单是一个重要的前提条件。对 LFLS 记录的详细调查表明，了解该时期的作业实践和原始清单的推导非常重要。这些见解应该有助于指导未来的努力，以更好地了解 LFLS 和其他地方的处置历史和清单。
