This article presents a method for assessing the radionuclide surface contamination density (SCD) on open sites and in premises of a radiation hazardous facility based on measurements of the ambient dose equivalent rate (ADER). The method is intended for use at the initial stage of the assessment of the radiation environment at facilities. The assessed SCD at a given location on the surface can differ from the directly measured SCD at that location, since sources located on the surface and distributed by the depth contribute to the ADER value. The method makes it possible to estimate SCD with reasonable accuracy without increasing the number of measurements, and thus avoid additional occupational exposure and the use of additional resources. SCD and ADER as spatial variables have different support of measurement data. For ADER, measured at a height of 1 m, the support of measurement data can be taken to be a circle in the centre of which a gamma-ray detector is located, with a radius of several tens of meters. In contrast, SCD has the support of measurement data, close to the overall dimensions of the beta detector (100 cm2). To solve the problem of SCD calculation on the basis of ADER measurements, the method of conversion coefficients (MCC) is usually applied, based on the use of conversion factors; however, this method provides an adequate estimate only under conditions of an SCD with low gradient over the surface. The method proposed in this article is applicable for an arbitrary distribution of SCD, and designed to deal with heterogeneous contamination patterns. The developed method is based on the numerical solution of the Fredholm equation of the first kind. The measurement data always contain an error, therefore, the task of the SCD calculation is an ill-posed problem, and the Tikhonov regularisation method (ridge regression) was used to solve it. The article presents the method developed and examples of use. Validation of the method was performed using 38 measurements of the radioactive contamination from 137Cs in soil. It is shown that the method proposed in the article demonstrates a significant superiority in comparison with the MCC method, because it allows more accurate localisation of areas contaminated with radionuclides and is applicable for an arbitrary distribution of SCD.

Andreeva Bay in northwest Russia hosts one of the former coastal technical bases of the Northern Fleet. Currently, this base is designated as the Andreeva Bay branch of Northwest Center for Radioactive Waste Management (SevRAO) and is a site of temporary storage (STS) for spent nuclear fuel (SNF) and other radiological waste generated during the operation and decommissioning of nuclear submarines and ships. According to an integrated expert evaluation, this site is the most dangerous nuclear facility in northwest Russia. Environmental rehabilitation of the site is currently in progress and is supported by strong international collaboration. This paper describes how the optimization principle (ALARA) has been adopted during the planning of remediation work at the Andreeva Bay STS and how Russian-Norwegian collaboration greatly contributed to ensuring the development and maintenance of a high level safety culture during this process. More specifically, this paper describes how integration of a system, specifically designed for improving the radiological safety of workers during the remediation work at Andreeva Bay, was developed in Russia. It also outlines the 3D radiological simulation and virtual reality based systems developed in Norway that have greatly facilitated effective implementation of the ALARA principle, through supporting radiological characterisation, work planning and optimization, decision making, communication between teams and with the authorities and training of field operators.

In the 1960s two technical bases for the Northern Fleet were created in the Russian northwest at Andreeva Bay in the Kola Peninsula and Gremikha village on the coast of the Barents Sea. They maintained nuclear submarines, receiving and storing radioactive waste and spent nuclear fuel. No further waste was received after 1985, and the technical bases have since been re-categorised as temporary storage sites. The handling of these materials to put them into a safe condition is especially hazardous because of their degraded state. This paper describes regulatory activities which have been carried out to support the supervision of radiological protection during recovery of waste and spent fuel, and to support regulatory decisions on overall site remediation. The work described includes: an assessment of the radiation situation on-site; the development of necessary additional regulatory rules and standards for radiation protection assurance for workers and the public during remediation; and the completion of an initial threat assessment to identify regulatory priorities. Detailed consideration of measures for the control of radiation exposure of workers and radiation exposure of the public during and after operations and emergency preparedness and response are complete and provided in sister papers. The continuing requirements for regulatory activities relevant to the development and implementation of on-going and future remediation activities are also outlined. The Norwegian Radiation Protection Authority supports the work, as part of the Norwegian Government's plan of action to promote improvements in radiation protection and nuclear safety in northwest Russia.

The site of temporary storage of spent nuclear fuel and radioactive waste, situated at Andreeva Bay in Northwest Russia, was developed in the 1960s, and it has carried out receipt and storage of fresh and spent nuclear fuel, and solid and liquid radioactive waste generated during the operation of nuclear submarines and nuclear-powered icebreakers. The site is now operated as the western branch of the Federal State Unitary Enterprise, SevRAO. In the course of operation over several decades, the containment barriers in the Spent Nuclear Fuel and Radioactive Waste storage facilities partially lost their containment effectiveness, so workshop facilities and parts of the site became contaminated with radioactive substances. This paper describes work being undertaken to provide an updated regulatory basis for the protection of workers during especially hazardous remediation activities, necessary because of the unusual radiation conditions at the site. It describes the results of recent survey work carried out by the Burnasyan Federal Medical Biophysical Centre, within a programme of regulatory cooperation between the Norwegian Radiation Protection Authority and the Federal Medical-Biological Agency of Russia. The survey work and subsequent analyses have contributed to the development of special regulations setting out radiological protection requirements for operations planned at the site. Within these requirements, and taking account of a variety of other factors, a continuing need arises for the implementation of optimisation of remediation at Andreeva Bay.

Abstract-The International Commission on Radiological Protection (ICRP) described its approach to the protection of the environment and how it should be applied in Publication 124. The report expanded on the Commission's objectives for environmental protection, and how the Derived Consideration Reference Levels (DCRLs) apply within different exposure situations. DCRLs relate radiation effects to doses over and above their normal local background radiation levels, and consider different potential pathways of exposure for animals and plants. This paper will describe how the DCRLs may be used within existing exposure situations to better understand the potential impacts on animals and plants. In these circumstances, the Commission recommends that the aim be to reduce exposures to levels that are within the DCRL bands (or even below, depending upon the potential cost/benefits), but with full consideration of the radiological and non-radiological consequences of doing so. Using examples, this paper will demonstrate how this may be achieved in practice, bearing in mind the potential exposure of humans, animals and plants during and following any remediation attempted.

The Coastal Technical Base (CTB) №569 at Andreeva Bay was established in the early 1960s and intended for the refueling of nuclear submarine reactors and temporary storage of spent nuclear fuel (SNF) and radioactive waste (RW). In 2001, the base was transferred to the Russian Ministry for Atomic Energy and the site remediation began. The paper describes in detail the radiation situation change at the technical site in Andreeva Bay from 2002–2016, the period of preparation for the most critical phase of remedial work: removal of spent fuel assemblies. The analysis of aggregated indicators and data mining were used. The article suggests the best number and location of checkpoints needed to ensure sufficient accuracy of the radiation situation description. The fractal properties of the radiation field are studied using the Hurst index. The relationship between checkpoints was assessed using the method of searching for checkpoint communities. The decrease in the integral of the ambient dose equivalent rate (ADER) at the technical site was evaluated by the method of time series decomposition. Three components of time series were identified: trend, seasonal and residual. The trend of the ADER integral over the technical site is a monotonic decreasing function, where the initial and final values differ tenfold. Taking into account that 137Cs dominates the radiation situation on-site, it is clear that the ADER due to the radionuclide decay will have decreased by 1.4 times. It is estimated that only a small proportion of 137Cs has migrated off-site. Therefore, approximately a sevenfold decrease in dose rate is mainly due to remediation activities of personnel. During the year, the seasonal component varies the ADER integral by a factor of two, due to snowfall. The residual component reflects the uncertainty of the ADER integral calculation and phases of active SNF and RW management. The methods developed are used to support the optimization of remediation work as well as regulatory supervision of occupational radiation protection.

In compliance with the fundamentals of the government's policy in the field of nuclear and radiation safety approved by the President of the Russian Federation, Russia has developed a national program for decommissioning of its nuclear legacy. Under this program, the State Atomic Energy Corporation 'Rosatom' is carrying out remediation of a Site for Temporary Storage of spent nuclear fuel (SNF) and radioactive waste (RW) at Andreeva Bay located in Northwest Russia. The short term plan includes implementation of the most critical stage of remediation, which involves the recovery of SNF from what have historically been poorly maintained storage facilities. SNF and RW are stored in non-standard conditions in tanks designed in some cases for other purposes. It is planned to transport recovered SNF to PA 'Mayak' in the southern Urals. This article analyses the current state of the radiation safety supervision of workers and the public in terms of the regulatory preparedness to implement effective supervision of radiation safety during radiation-hazardous operations. It presents the results of long-term radiation monitoring, which serve as informative indicators of the effectiveness of the site remediation and describes the evolving radiation situation. The state of radiation protection and health care service support for emergency preparedness is characterized by the need to further study the issues of the regulator-operator interactions to prevent and mitigate consequences of a radiological accident at the facility. Having in mind the continuing intensification of practical management activities related to SNF and RW in the whole of northwest Russia, it is reasonable to coordinate the activities of the supervision bodies within a strategic master plan. Arrangements for this master plan are discussed, including a proposed programme of actions to enhance the regulatory supervision in order to support accelerated mitigation of threats related to the nuclear legacy in the area.

In the 1960s, two technical bases of the Northern Fleet were created in Northwest Russia, at Andreeva Bay in the Kola Peninsula and Gremikha village on the coast of the Barents Sea. They maintained nuclear submarines, performing receipt and storage of radioactive waste and spent nuclear fuel, and are now designated sites of temporary storage (STSs). An analysis of the radiation situation at these sites demonstrates that substantial long-term remediation work will be required after the removal of the waste and spent nuclear fuel. Regulatory guidance is under development to support this work. Having in mind modern approaches to guaranteeing radiation safety, the primary regulatory focus is on a justification of dose constraints for determining acceptable residual contamination which might lead to exposure to workers and the public. For these sites, four principal options for remediation have been considered-renovation, conversion, conservation and liquidation. This paper describes a system of recommended dose constraints and derived control levels formulated for each option. The unconditional guarantee of long-term radioecological protection provides the basis for criteria development. Non-exceedance of these dose constraints and control levels implies compliance with radiological protection objectives related to the residual contamination. Dose reduction below proposed dose constraint values must also be carried out according to the optimisation principle. The developed criteria relate to the condition of the facilities and the STS areas after the termination of remediation activities. The proposed criteria for renovation, conversion, conservation and liquidation are entirely within the dose limits adopted in Russia for the management of man-made radiation sources, and are consistent with ICRP recommendations and national practice in other countries. The proposed criteria for STS remediation and new industrial (non-radiation-hazardous) facilities and buildings on the remedied sites had, until now, no analogues in the Russian system of regulation of radiation-hygienic standardisation. The proposals made here may serve as a basis for corresponding standards at other sites.