4.1 Radiation protection optimization (ALARA) – is a constituent of the program directed to achievement and keeping of acceptable safe conditions of activity.
Radiation protection must be a component of overall program for safe work conditions assurance.
4.2 An optimization principle must be applied at all stages both of the manufacturing process arrangement and of the radiation facility operation: from design stage, in the course of operation and up to termination of the facility decommissioning and waste disposal.
4.3 ALARA technique involves:
• generation of conditions for opening and implementation of each worker potentials (knowledge, skills, experience);
• justified selection and preliminary planning of actions, implementation of which improves safety;
• preparedness for work implementation;
• analysis and evaluation of operations performed, account of experience gained.
4.4 Subjects of optimization (keeping at reasonably achievable low level) are:
• dosimetric costs of workers (individual and collective doses) under priority of individual doses;
• activity of discharges/effluents;
• specific activity and total amount of RW generated.
5 Guidance for the optimization principle introduction
5.1 To manage development and taking actions for optimization principle implementation, ALARA group is arranging at SevRAO facility No.1 (based on the current radiation safety division) under the chief engineer presidency.
5.2 ALARA group considers issues of radiation hazardous operation arrangement, including:
• ways of the personnel involvement into work planning;
• preparedness for work under radiation hazardous conditions;
• control of protective/preventive measures;
• analysis and evaluation of results obtained, account of the experience gained.
6 Introduction of the optimization principle
6.1 Work planning
6.1.1 When planning radiation hazardous operations, different options of their performance shall be considered. Options accompanied with the least dose costs are top priority. At that, a variant of the operation performance connected with the least individual occupational doses is preferable.
6.1.2 Such options of work performance must also have advantage, which ensure minimum discharges
6.2 Pre-starting procedure
6.2.1 In the course of pre-starting procedure, the preliminary analysis is carried out of experience gained in similar operations to identify actions aimed at limitation of occupational doses.
6.2.2 Selection is made of optimum numerical and personal strength of the team to the operation performance. Optimum number of persons in the team is minimum number of workers, able to perform the operation within the particular period.
6.2.3 Means are specified for communication between members of the team, and for interaction with work leaders, and with dosimetry division responsible for dose monitoring in the course of work.
6.2.4 Pre-starting procedure includes the personnel exercises with the purpose of training safe skills of working operation. As necessary, exercises are performed using training apparatuses. Qualified and educated personnel are able to accomplish the same work within a shorter period and with lower dose costs. Each worker must be interested in dose cost reduction.
6.2.5 Optimal ergonomic tools and instruments are selected, including gripping devices, manipulators, computer-aided installations etc.
Before the beginning of work, radiation survey of an assumed workplace is carried out.
6.2.6 Subdivision of the site into some special areas is performed. Such places are indicated in the map, which are characterized by the highest external gamma dose rate, where time of the personnel staying is limited. Places characterized by the lowest external gamma dose rate are indicated in a special manner, to show areas for the personnel staying, as possible (for example, when performing pre-starting operations, or in free time etc.). The personnel routes are indicated across the site to restrict external exposure.
6.2.7 Protective (preventive) actions are taken:
• set protective screens and floor-mats;
• equipment with additional ventilation and exhausts;
• dust pressing;
• application of film coatings.
6.2.8 Correct workplace arrangement helps to dose cost reduction in the course of work. It is reached by means of qualitative and fast performance of:
• selection of optimal PPE, assuring the required protection coefficient, and not affecting work conditions, at the same time;
• sufficient illumination;
• normal microclimate;
• absence of mechanical difficulties.
In case of necessity, special instructions shall be developed of safe work implementation.
6.2.9 Authorized doses, permissible work duration, reference levels of radiation factors are calculated and the dose warrant/permission is made.
This permission indicates:
• name of the operation;
• data of the operation performance;
• place of the operation performance;
• reference levels of radiation factors (external gamma dose rate and activity concentration of beta-aerosols, etc.);
• authorized individual effective and equivalent doses;
• work duration (maximum time of staying at the particular area);
• individual and collective PPE applied;
• listing of safety measures and radiation protection instructions, requirements of which are necessary for observance in the course of work.
The needed extent of radiation monitoring is identified, including emergency monitoring.
6.2.10 Before the beginning of work under radiation hazardous conditions, the personnel are subjected to obligatory medical examination.
6.3 Work implementation
6.3.1 Operations, mentioned in the warrant/permission are performed accompanied with the dosimetrist, who carries out the required radiation monitoring. Moreover, the personnel implement self-monitoring using personal dosimeters, which also measure external gamma dose rate. The established thresholds of excess reference level alarm are set in these dosimeters.
6.3.2. In the course of work, two-way communication must be provided between operator and the work leader, as well as between operator and accompanied dosimetrist.
6.4 Analysis and evaluation of the results
6.4.1 After termination of work, the results are to be analyzed. The obtained doses (both individual and collective) are compared with the predicted (authorized) values.
If authorized levels are exceeded, the reasons are ascertained to avoid similar events in future.
6.4.2 Effectiveness is evaluated of completed measures aimed at reduction of dose costs. A brief report is made containing conclusions and recommendations useful for arrangement similar operations in future.
6.5 Involvement of the personnel into implementation of the optimization principle
6.5.1 The conditions must be arranged, when the personnel deliberately select such ways, methods and work organization, which promotes achievement of the highest results (regarding quality and safety) under minimum time costs for work implementation.
6.5.2 The personnel, on its own, must take measures and methods of protection against ionizing radiations, such as:
• protection by distance;
• protection by time;
• correct application of all type PPE;
• using computerized and automated apparatus, facilities and equipment.
ALARA committee in cooperation with the administration must develop a system of stimulation of work implementation under dose cost minimization accompanied with exactingness and compulsion (presence of the work leaders at radiation hazardous operation performance, periodic and unscheduled inspections, control implemented by the radiation safety division)