|Year : 2012 | Volume
| Issue : 1 | Page : 17-21
Occupational exposures in industrial application of radiation during 1999-2008
Suresh Shantaram Sanaye, Sujatha Baburajan, Suresh Ganpat Pawar, Shailesh Krishna Nalawade, Balvindar Kaur Sapra
Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India
|Date of Web Publication||6-May-2013|
Suresh Shantaram Sanaye
Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085, Maharashtra
Source of Support: None, Conflict of Interest: None
Radiation sources are used in various industrial applications like industrial radiography, industrial irradiation, industrial fluoroscopy, nucleonic gauges, well logging etc.. Gamma, beta X-ray as well as neutron sources are used for various applications. Number of radiation workers in this field has increased over the years. Due to operating conditions prevailing during the exposure as well as the strength of the sources used in some of the applications, radiation protection plays an important role in this field. Analysis of doses received by radiation workers in industry provides information on trends of doses as well as adequateness of radiation protection practices followed in this sector. In India, National Occupational Dose Registry System (NODRS) of Radiological Physics and Advisory Division (RPAD), Bhabha Atomic Research Centre (BARC) maintains personnel dose information of monitored radiation workers in the country. Analysis of occupational dose data of industrial radiation workers for last 10 years, i.e., 1999-2008 has been presented in this paper. It is observed that even though there is an increase in monitored radiation workers, percentage of persons receiving radiation exposure has come down during this period. There is also a decrease in the average annual dose as well as the collective dose. Further analysis of sub-categories shows that industrial radiography operations are the main contributor for collective dose (about 77%) followed by well logging and industrial X-ray operations (about 8% each). Thus, in addition to industrial radiography, attention is also to be given to operations in these areas.
Keywords: Dose registry, industrial radiography, occupational exposure, personnel monitoring
|How to cite this article:|
Sanaye SS, Baburajan S, Pawar SG, Nalawade SK, Sapra BK. Occupational exposures in industrial application of radiation during 1999-2008. Radiat Prot Environ 2012;35:17-21
|How to cite this URL:|
Sanaye SS, Baburajan S, Pawar SG, Nalawade SK, Sapra BK. Occupational exposures in industrial application of radiation during 1999-2008. Radiat Prot Environ [serial online] 2012 [cited 2021 Apr 13];35:17-21. Available from: https://www.rpe.org.in/text.asp?2012/35/1/17/111405
| Introduction|| |
Application of radiation in industry, medicine and research sector has increased significantly over the years. In industry radiation, sources are used in applications such as industrial irradiation, industrial radiography, industrial fluoroscopy, luminizing, nucleonic gauges, well logging. In industrial radiography, which is a non-destructive testing technique, sealed sources of radioactive material or X-ray generating machines as well as linear accelerators are used for taking radiographs to detect (flaws in metal structures and welding seals) defects in pipes, walls and variety of structures. In well logging, gamma or neutron sources are used to determine elemental composition of soil at depth generally for mineral, oil or gas exploration. In nucleonic gauges, gamma or neutron sources are used to monitor the flow of liquid, measure and control the thickness of metals, films, papers and plastic as well as to monitor density of material. In fluoroscopic applications, X-rays are used to determine content and composition of materials. Most of the applications in industrial irradiation are the sterilization of medical and pharmaceutical products, preservation of foodstuffs, polymer synthesis and modifications, and the eradication of insect infestation. High dose gamma or electron-beam facilities are used for this purpose. Luminizing is one of the oldest industrial uses of ionizing radiation. In this alpha or beta emitters were mixed with a phosphor such as zinc sulphide and then painted on dials, such as watch faces or airplane instrumentation. Presently, they are used in exit signs and map illuminations.
Since the strength of the source used is generally high in some of the industrial applications as well as the operating conditions prevailing during the exposure, radiological protection plays an important role in this sector. Analysis of dose data of radiation workers in industry provides some insight into trends in occupational exposures received by industrial radiation workers (Currivan et al., 2001;  Colgan et al., 2008  ). This helps in providing information on adequateness of radiation protection practices followed in the industry. Availability of such data is also a requirement of some international bodies (UNSCEAR Report, 2008  ) for arriving at worldwide trend in such applications.
Occupational exposures of monitored radiation workers in the country are maintained and updated by National Occupational Dose Registry System (NODRS) of RPAD, BARC (Sanaye et al., 2010  ). This paper presents the trends in occupational exposure received by radiation workers in the industry during past 10 years (1999-2008).
| Materials and Methods|| |
Personnel monitoring of radiation workers in India is carried out using CaSO 4 : Dy based thermo luminescent dosimeters (TLD). External dose due to X, gamma and beta radiations are monitored using this TLD. Three private labs accredited by BARC are carrying out TLD personnel monitoring services to radiation workers from Non-DAE institutions. All radiation workers are first registered with NODRS of RPAD, BARC (Sanaye et al., 2010  ). The accredited labs issue TLD badges to registered radiation workers, receive the used TLD badges after the monitoring period, process the dosimeters and generate the dose reports. The labs then send this dose data of monitored radiation workers to NODRS. Monitoring of radiation workers for neutrons is carried out by Neutron Monitoring Group of RPAD, BARC using CR-39 Solid State Nuclear Track Detector (SSNTD). The neutron dose data received from this group is updated to respective records in NODRS. The registry maintains and updates the dose as well as personal data of all monitored radiation workers in the country. Approval from Atomic Energy Regulatory Board (AERB) is required for registration of new institution and/or new radiation workers from industry.
The TLD system has minimum reporting dose (MRD) of 0.10 mSv for gamma radiation, 0.50 mSv for beta radiation and 0.05 mSv for X-rays (Sneha et al., 2010  ). For neutrons, MRD is 0.20 mSv. All doses that exceed the level of 10 mSv in a monitoring period are always investigated. The result of the investigation is the dose assigned to the wearer. The dose record is accordingly amended after receiving final recommendation from the Investigation Committee. The database, therefore, includes only actual doses received by the radiation workers.
The database of NODRS contains personal as well as dose data of all monitored radiation workers. It regularly provides annual-cum-five year dose history of its radiation workers to each active institution. It also carries out analysis of doses received by the radiation workers and the results are provided to different authorities. Such type of analysis helps in confirming that radiation safety standards and dose limits stipulated by regulatory authorities are strictly followed. It also gives information on whether the work practices followed are safe or not.
| Results and Discussion|| |
The doses received by radiation workers from industry during last 10 years (i.e., 1999-2008) have been analyzed and presented in this paper.
Monitored and exposed radiation workers
The occupational radiation workers in industry have gradually increased over the years. There were about 7,200 radiation workers monitored during 2008 as against 5,300 during 1999 showing an increase of about 35% in 10 years. The number of institutions using radiation for industrial applications also increased from 555 to 622 during this period. Even though there is an increase in the number of monitored radiation workers, percentage of exposed persons, receiving the measurable dose (i.e., occupational doses ≥ MRD), has come down from 50% to 56% in first 4 years to 30-40% in last 4 years. The trend of monitored and exposed persons receiving the measurable dose is shown in [Figure 1].
|Figure 1: Number of monitored radiation workers as well as those who received occupational doses ≥ minimum reporting dose in industry|
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Distribution of collective dose
The collective dose during this period shows steady decreasing trend from 5.5 to 2.5 person.Sv upto year 2006. Thereafter, an increasing trend is seen upto 4 person. Sv in 2008. The collective doses during 1999-2008 are shown in [Figure 2]. During this period, percentage of monitored persons who received doses in the range: 0.05-1 mSv is 31%, 1-5 mSv is 9.2%, 5-10 mSv is 1.7%, 10-20 mSv is 0.9%, 20-30 mSv is 0.2% and > 30 mSv is 0.2%. Remaining persons (56.8%) received zero doses. Similar statistics, only for the radiation workers who received the exposures, is shown in [Figure 3]. The pie-chart indicates the percentage of exposed persons in that range.
|Figure 3: Distribution of exposed radiation workers in different dose ranges|
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Average annual dose
The average annual dose shows overall decreasing trend from 0.99 mSv to 0.44 mSv. Average annual dose of exposed persons was within 1.28-2.25 mSv during this period as shown in [Figure 4]. Most of the monitored radiation workers are within the annual limit, only about 0.2% exceeded the annual limit of 30 mSv. This decreasing trend in average annual doses is due to advancement in technology, improvement in radiation protection practices as well as better regulatory control.
Analysis of industrial sub-category
Further analysis for industrial sub-categories was carried out to evaluate the trends in these subcategories in monitored persons, exposed persons, collective dose, and average annual dose of monitored as well as exposed persons. The number of radiation workers monitored as well as exposed are highest in industrial radiography in comparison to the rest of the sub-categories [Figure 5] and [Figure 6]. It is observed that 77% of the collective dose is contributed by industrial radiography, 8% each by well logging and industrial X-rays, and remaining by others [Figure 7]. Collective doses for different intervals are shown in [Figure 8].
|Figure 5: Number of monitored radiation workers in industrial sub-categories|
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|Figure 8: Distribution of doses in different intervals for various industrial sub-categories|
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The average annual doses for monitored as well as exposed persons from industrial sub-categories are shown in [Figure 9] and [Figure 10]. The average annual dose in industrial radiography is highest compared to rest of the industrial sub-categories, and it was in the range of 0.52-1.27 mSv. However, in case of the average annual dose of exposed persons, the dose values for industrial radiography and industrial X-rays are comparable and were in the range of 0.94-2.76 mSv.
|Figure 9: Average annual dose of monitored workers from industrial sub-categories|
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|Figure 10: Average annual dose of exposed workers from industrial sub-categories|
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| Conclusion|| |
Analysis of occupational exposures in industrial application during 1999-2008 shows a gradual increase in the occupational radiation workers. The number of person monitored as well as exposed are highest in industrial radiography compared to other sub-categories. Major contribution to collective dose is also from industrial radiography followed by industrial X-rays and well logging. Occupational exposures of most of the monitored industrial radiation workers are well below the annual dose limit. Overall decreasing trend in average annual doses indicates improvement in radiation protection practices as well as better regulatory control.
From the analysis, it is clear that in addition to industrial radiography, more attention is also to be given to operations in the area of industrial X-rays as well as well logging to further reduce the occupational exposures.
| References|| |
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|3.||Sources and Effects of Ionizing Radiation, United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR 2008, Report to the General Assembly with Scientific Annexes, Volume I, 223, Annex B. Exposures of the public and workers from various sources of radiation. United Nations, New York, 2010. |
|4.||Sanaye SS, Meena RH, Baburajan S, Pawar SG, Sapra BK, Mayya YS. Networked national occupational dose registry system. Radiat Protec Environ 2010;33:167-70. |
|5.||Sneha C, Pradhan SM, Adtani MM. Study of minimum detection limit of TLD personnel monitoring system in India. Radiat Prot Dosimetry 2010;141:168-72. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]