Development of the Nation-Wide Dosimetric Monitoring Network in Ukraine

Transcription

1 Development of the Nation-Wide Dosimetric Monitoring Network in Ukraine V.Chumak 1, A.Boguslavskaya 2, A.Musijachenko 1 1 Scientific Center for Radiation Medicine AMS Ukraine, Melnikova, 53, Kiev, Ukraine chumak@leed1.kiev.ua 2 Ministry of Health, 01021, Grushevsky str. 7, Kiev, Ukraine Abstract. Development of the nation-wide network for monitoring and registration of individual doses is being in progress in Ukraine. The need for urgent action is caused by the fact, that despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralized dose accounting system in Ukraine, existing dosimetry services operate obsolete manual TLD readers and no methodological unity is observed by the dosimetry services. Presently the mixed dosimetric monitoring is practiced in Ukraine. Nuclear power plants and some major nuclear facilities have their own dosimetry services responsible for dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by territorial dosimetry laboratories affiliated to sanitary and epidemiology supervision bodies. In total these services cover about 38,000 occupationally exposed workers, including 5,500 in medicine, 16,400 employees of five nuclear power plants and about 16,000 workers dealing with other sources of occupational exposure (industry, research, military). It is prescribed by the governmental decree that three-level united state system assigned to covering all aspects of efficient dosimetric monitoring should be established. The tasks of the system, in particular, are: securing methodical unity of individual dosimetric monitoring; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programs; development and support of information infrastructure for logging, storage and access to data on individual dosimetric monitoring, in particular - keeping the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. In its development, the national system will be guided by international experience and will be established according to the best practices and in agreement with the EURADOS network of excellence concept. 1. Introduction One of the main components at realization of the all-round monitoring of ionizing radiations at action of radiation and radioactive material is the individual dosimetry monitoring of workers and population. Dosimetric monitoring allows addressing the problems related to maintenance of the proved policy of radiating safety of people. To such problems concern: carrying out of an estimation of an actual irradiation of people for an establishment of conformity to working specifications of radiating safety; estimation and development of optimum operational procedures on the basis of the analysis of results of monitoring; showing information on working conditions at workplaces and influence of change of modes of operation on radiological working conditions; showing of the information for an estimation of doses in case of irradiation due to radiation accident; informing personnel about conditions of irradiation and search of ways of decrease doses of an irradiation; acknowledgement of the rational organization of practice.

2 In many countries positive experience of realization of individual dosimetry monitoring is accumulated. In the USA governmental (Department of Energy) and commercial services of an personal dosimetric monitoring operate. All such services pass accreditation according to DOELAP (DOE Laboratory Accreditation Program) or NVLAP (National Voluntary Laboratory Accreditation Program) requirements, supported by NIST (National Institute of Standards and Technology). Keeping records of individual dose measurements is realized in two independent systems: DOE Radiation Exposure Monitoring System (REMS) personnel of Department of Energy enterprises and NRC Radiation Exposure Information and Reporting System (REIRS) data of workers of license-holder the Commission of the nucleus regulation of the USA In Canada, as from 1951 acts National Dosimetry Service (NDS) at Ministry of health. National Dose Registry (NDR) operates at Ministry of health and includes rows about doses regardless of departmental subservience: NDS, commercial dosimetry services, nuclear power company or uranium mill. NDR contains dose records for about 550 thousand professional workers as from The Current individual monitoring covers 130 thousand professional workers. In European countries good deal of effort is allocated by EURADOS to harmonization of dosimetric monitoring in European countries. Major attention is allocated to the national dosimetry registry operation and European systems of data exchange, the efficient quality assurance programs. Examples of dosimetry registries are shown in Table 1 Table 1. Examples of dosimetry registrears Registry name Country Amount persons on account NRC Radiation Exposure Information and Reporting Systems USA DOE Radiation Exposure Monitoring System USA National Registry for Radiation Workers Great Britain National Dose Registry (NDR) Canada Personal Radiation Monitoring Service (PRMS) Australia Current status of dosimetric monitoring in Ukraine In Ukraine the number of individuals exposed occupationally, medically or by residence in the areas with technogenically enhanced levels of radiation is scoring tens of thousands. Unfortunately, individual dosimetry is performed by uncoordinated laboratories, using obsolete equipment and practicing

3 inadequate measurement techniques, there is no centralized infrastructure for concentration and dissemination of information on individual doses. Aforesaid calls for elaboration of the nationwide System for management and coordination of dosimetric monitoring as well as deep modernization of existing dosimetry services. Presently Ukraine has mixed system for dosimetric monitoring. Nuclear power plants and some major nuclear facilities have their own dosimetry services, which are responsible for regular dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by dosimetry laboratories affiliated to the territorial authorities for sanitary and epidemiology supervision. In Ukrainian Ministry of Health performed survey of the status of dosimetric monitoring and inventory of critical groups requiring such monitoring. Dosimetry services in Ukraine cover about 38,000 occupationally exposed workers, including 9,100 medical professionals, 16,400 employees of 5 nuclear power plants and ca.12,400 workers dealing with other sources of occupational exposure (industry, research) (Figure 1). Territorial dosimetry services operate in 13 of 24 oblasts of Ukraine, using DTU-01 manual TLD readers produced with one exception in The coverage of critical groups by dosimetric monitoring is variable and ranges from 38% to 100% depending on the oblast. Regional individual dosimetric monitoring (IDM) services are capable to conduct measurement of dose caused by high energy photons only, doses beta-, neutron and soft photons radiations remain uncontrolled. Also are not checked dose on lens of the eye and superficial (skin) doses. The raw results are not stored, thus not allowing to create legal dose records. In the majority of territorial dosimetry services the electronic systems (databases) of dose records registrations and keeping are absent. None of dosimetry services has access to the web and only few dosimetry laboratories have access to ; none of services transmit their results to the central authorities electronically. Personnel of nuclear power plants NPP (about 16,400 workers) is monitored by their own dosimetry services achieving absolute coverage of the main staff and temporary workers. IDM instrumentation and coverage are shown in Table 2. Instrumentation used for monitoring of nuclear workers is different: Chernobyl NPP operates new Harshaw 8800 TLD systems, semi-automated TLD system AKIDK-101 (Russia) is used in Ryvne NPP; personnel of three other NPP is monitored using manual TLD readers KDT-02M. Each of five NPP has its own data environment. However, the software and data formats are not compatible, hampering thus data flow even within the same Atomic Energy Company to which four operational NPPs belong. There is also no unity in the dose assessment methodology, in particular dosimetric monitoring services do not assess effective dose, providing readouts in terms of dose equivalent instead.

4 Nuclear industry (43%) Industry 3676 (10%) Rivne NPP 3002 (8%) Khmelnitsky NPP 2000 (5%) Medicine 9100 (24%) Zaporizhzhya NPP 4980 (13%) South Ukrainian NPP 2520 (7%) Chernobyl NPP 3900 (10%) Other 107 (19%) Research and education 1473 (4%) FIG.1. Structure of Ukraine Dosimetry services coverage Table 2. Nuclear power plants dosimetry services Nuclear power plant Instrumentation Year of installation Number of dosimeters IDM covered persons Chernobyl NPP Нarshaw South Ukrainian NPP КДТ-02М Zaporizhzhya NPP КДТ-02М Rivne NPP АКІДК Khmelnitsky NPP КДТ-02М Dosimetric monitoring of medical personnel is mainly performed by the single service - Central laboratory of radiation hygiene of medical personnel affiliated to the Grigoriev Institute of Medical Radiology AMS Ukraine in Kharkiv. Totally, 5,500 medical staff members are monitored by this service on quarterly basis using obsolete manual TLD readers DTU Elaboration of the united system According to the national guidelines for development of the united System for monitoring and registration of individual doses, it is planned to develop three-level national network covering all population, which is exposed occupationally or due to residence in the areas with technologically enhanced level of exposure

5 The System is intended to cover all aspects of efficient dosimetric monitoring, in particular - provision of methodical unity of individual dosimetric monitoring, scientific and methodological guidance of individual dosimetric control, procurement of common technical policy regarding nomenclature and operation of instrumentation, implementation of quality assurance programs, development and support of common information infrastructure intended for logging, storage and access to data on individual dosimetric monitoring as well as keeping the national registry of individual doses, training and certification of personnel engaged in the System of individual dosimetric monitoring. Three levels of the System (Figure 2, Table 3) have different goals and responsibilities. Table 3. Tasks of the Levels of the united System Level 1 Level Central IDM lab, dosimetry registry and coordination centre Level 2 Regional IDM services Level 3 (a) well equipped dosimetry laboratories of the NPPs Level 3 (b) territorial sanitary and epidemiology stations Level 3 (c) independent services after proper accreditation Tasks Development of the guidelines in the area of dosimetric monitoring and data handling; provision of methodological support for operation of the System; development and implementation of the unified technical policy; development of the information infrastructure; analysis and dissemination of data regarding the results of dosimetric monitoring; training and quality assurance for the local dosimetric monitoring facilities. Maintain regional dosimetry registries; concentrate the results of dosimetric monitoring performed in the region of their responsibility by all dosimetry services incorporated into the System; take over routing dosimetric monitoring in respective territories (later, when laboratories of the second level will equipped with modern equipment). Routine dosimetric monitoring of the personnel; dosimetry database management and keeping raw data of dose measurement; transfer of the results of dosimetric monitoring to the State dosimetry registry. Distribution and collection of dosimeters, which are issued by the laboratories of the first and second levels; supervision of the usage of dosimeters; feedback to end users transfer of the results of monitoring to persons and management; maintaining of the local level of the State dosimetry registry. Dosimetric monitoring on commercial basis following methodological guidance provided by the first level of the System; keeping of the raw data of dose measurement; transfer of the results of dosimetric monitoring to the State dosimetry registry.

6 FIG. 2. Structure and operation flowchart of the unified state System for monitoring and registration of individual doses of population The process of development of the System will have several stages. At the first stage information infrastructure of the System should be established and measures will be taken for harmonization of the measurement techniques. At the second stage well equipped central laboratory will be established eliminating inefficient small dosimetry services. At the third stage regional laboratories (Level 2) will be established and equipped with modern instrumentation. Realization of such system of the individual dosimetry monitoring requires involving significant financial and material resource, conducting of organizational, research and scientifically-methodical works. Therefore, for the quick starting of the System in Ukraine, it is proposed to build two-level system, according to the scheme showing on Fig.3. Such two-level system will solve several of the priority problems, as given in Tabl.4

7 FIG. 3. Structure and operation flowchart of the project of 2-level base System for monitoring and registration of individual doses of population 4. United System realization today The main priorities of elaboration of the United System today are creation of the scientific-methodical center of individual dosimetry monitoring, analysis of a conditions of material and methodical bases, and accreditation programs for the third level laboratories, development of a detailed plan of measures on creation of territorial system of individual dosimetry monitoring, elaboration of technical specifications for upgrading dosimetry laboratories. Elaboration of the three-level System in Ukraine is being conducted at slow pace due to severe lack of funds, needed for development of the mechanism for enforcement of radiation safety and radiation protection of the population of the Ukraine via adequate dosimetric monitoring and dose registration. However, according to recent decision of the National commission of radiation protection of Ukraine from November 28, 2003, it is recommended to develop and approve the Statute of the Methodological centre - Central dosimetry register as the key components of the United System for monitoring and registration of individual doses in Ukraine. At the moment, main expectations of the fast promotion of the proposed plan are associated with the international help, in particular incorporation of this activity into the on-going IAEA national project UKR/9/021 Strengthening Infrastructure for Nuclear and Radiation Safety.

8 Table 4. Tasks of the 2-level base System Level Tasks Level 1 Central IDM lab, dosimetry registry and coordination centre, Development of the guidelines in the area of dosimetric monitoring and data handling; provision of methodological support for operation of the System; development and implementation of the unified technical policy; development and maintenance of the State dosimetry registry; development and maintenance of the information infrastructure; analysis and dissemination of data regarding the results of dosimetric monitoring; training and quality assurance for the local dosimetric monitoring facilities; routine dosimetric monitoring. Central laboratory of radiation hygiene of medical personel affiliated to the Grigoriev Institute of Medical Radiology AMS Ukraine in Kharkiv, Routine dosimetric monitoring of the medical personnel; provision of methodological support for operation of the System, dosimetry database management and keeping raw data of dose measurement; transfer of the results of dosimetric monitoring to the State dosimetry registry. NPPs dosimetry services laboratories,) Routine dosimetric monitoring of the personnel; dosimetry database management and keeping raw data of dose measurement; transfer of the results of dosimetric monitoring to the State dosimetry registry. Level 2 Regional IDM services Dosimetric monitoring basis following methodological guidance provided by the first level of the System, maintain regional dosimetry databases; keeping of the raw data of dose measurement; transfer of the results of dosimetric monitoring to the State dosimetry registry; distribution and collection of dosimeters, which are issued by the laboratories of the first levels; supervision of the usage of dosimeters; feedback to end users transfer of the results of monitoring to persons and management.

9 5.Conclusions Current inadequate status of dosimetric monitoring infrastructure in Ukraine demands an urgent elaboration of the united state system for monitoring and recording of individual doses. The proposed plan would allows to bring dosimetry infrastructure in Ukraine to the modern state which would be compatible with existing and future European and international radiation protection networks. Unitary structure of Ukraine, strong administrative command and good communications between regions of the country are positive factors in favour of efficient implementation of the proposed plan. Deficiencies are associated with limited funding of this effort.