Framework and regulatory guidance to perform safety assesments for mining and mine remediation activities

Abstract

This study provided the opportunity to apply the source-receptor-pathway method of solving challenges. The source being the initiation point of the challenge; the pathway, being the routes towards the receptor; and the receptor, being the end point or result of the study. Potential solutions are reverted back to the pathway to be trailed to optimise the effect on the receptor. This study attends primarily to two challenges. These challenges were identified by the National Nuclear Regulator (NNR). The challenges prevent the optimised protection of the members of the public in the natural occurring radioactive material (NORM) industry. The first being the quantification of the effects of authorised release of liquid and gaseous effluents from on-site operations to off-site locations. New national and international information are considered to enhance the efficiency of methods and criteria applied to optimise the safety of the public. Therefore, it is required to periodically review and improve the acceptance criteria and assessment methodology applied to produce results. The second operational challenge addressed in this study is the remediation of existing exposure scenarios, such as land radiologically contaminated as a result of historical unregulated actions. Current regulations only make provision for the management of regulated actions. Secondly, because of the nature of the situation, special release criteria needed to be developed to manage these sites, which exceed current generic radiation safety criteria without allowing undue risks to members of the public. The situations for which resolutions are required differ from the current regulated situations. Therefore, a methodology, acceptable to the National Nuclear Regulator, in terms of compliance with the applied principles, was developed as a guide to provide insight in the acceptability of a methodology. In both situations, public safety assessments and remediation, there are several other systematic hinges in the framework that must be managed before the challenges are adequately dealt with. The first hinge is the legislation that allows the operator to perform specific actions within specified boundaries. To change national legislation is a mammoth task, which is not dealt with in this context. This study, to be effective, needed to demonstrate the inadequacies in existing legislation and what can be done to improve it. The needs identified in this study are now included in proposed new regulations, as it co-insides with a NNR process of updating national standards to be published when processed and approved. The second hinge in the framework, is all the internal processes at the National Nuclear Regulator that needed to be improved. These processes, include amongst others, development of a remediation framework, development of acceptance criteria, development of authorisation procedures and the development of a review guide for staff of the NNR, etc. In conclusion, this study improved and made available the following: - a revised methodology for the determination of the dose to members of the public from radioactive effluents (gaseous and liquid) released into the public domain from planned activities; - a new methodology for the determination of the dose to members of the public from existing exposure situations; - criteria for the release of land on existing exposure situations, after remediation from regulatory control; - the development of a process for the authorisation of existing exposure situations; - improvement of national regulations on the management of the dose to the public; - the development of national regulations to manage existing exposure situations; - tested methodologies, from scenarios compiled, to demonstrate that the assessment methodologies developed, can be effectively applied in practice; and - a guide document, to be used by the regulator for the review of a safety assessment on the dose to the public, for planned and existing exposure situations, submitted to the regulator for approval. In addition to the issues addressed in this study, several other challenges, which require further attention, were identified. Some of these issues are as follow: - the release of legacy sites from regulatory control may require restrictions on future land use; it could, under specific conditions, be impossible to release land that has been remediated to the 0.5 Bq/g exclusion levels, because the modelled doses may exceed 20 mSv/a, especially where Ra-226 is a contaminant; and - the proposed new regulations address the build-up of radio nuclides in the environment and the ingrowth of progeny, but it is not explicit on the time frames to which provisions for safety should be made; - plant species to be suitable for commercial or economically viable phytoextraction for radioactively contaminated soils should be further investigated for South African conditions