Radioisotope Applications in Industry

Besides electricity generation the other objectives of the Atomic Energy Programme in India is development and promotion of applications of radioisotopes and radiation technology in all major fields of human endeavor. One major area of industrial applications of radioisotopes is their use as sealed radioactive sources and as radioactive tracers for troubleshooting, process control and process vessel design modification. These applications are mostly
• on-line,
• non-destructive and
• non-invasive.

The use of these techniques is growing steadily as more and more potential problems are identified and are widely used in oil, gas, chemical, petrochemical, steel, mining, paper, mineral and automobile industries.
In India, Board of Radiation and Isotope Technology (BRIT), Department of Atomic Energy supplies radioisotope products and radiation equipment while the Radiochemistry and Isotope Group, Bhabha Atomic Research Centre undertakes R&D programmes for advanced applications and offers professional service.

India is the Thematic Sector Lead Country for Industry Sector for IAEA/RCA programmes since 2001. The main projects under the industrial sector deals with;
• Non-destructive Testing
• Radiotracer and Sealed source applications for industrial troubleshooting and process optimization.
• Nucleonic Control systems
• Radiation processing applications for material modification and environmental pollution remediation.

Sealed Source Applications

In sealed source applications, the radioisotope remains permanently sealed within the source capsule and makes no contact either with the plant or the process material. Radiation from the source is directed at the item of interest and by analyzing the modified radiation pattern, either in transmitted or in scattered beam, conclusions are drawn about the internals of the test material. Due to their greater penetrating power, gamma and neutron sources are most useful in problem - solving applications. The major areas in which radioisotopes are used in sealed form are:
•Non-destructive testing of castings and welding and other industrial products by gamma radiography technique.
• Industrial computed tomography
• Gamma scanning of industrial process columns
• Nucleonic gauges for level control of liquids and other materials in closed columns, thickness, density and composition measurement, soil moisture and density gauges, well logging tools for oil well exploration studies and mining industries.
• Radiation processing for material modification and environmental pollution remediation.

Non –destructive [Radiography] Testing
192Ir and 60Co are the two most widely used gamma radiography sources in industries. 170Tm, 75Se and 137Cs are also used in a limited manner. Isotope radiography have many advantages over X-ray machines such as portability, freedom from electric power requirement and possibility of use of tiny isotope sources in otherwise inaccessible areas of an industrial system. Radiography is a mandatory requirement for inspection of welds and castings in many areas of industrial activity.
Realizing the importance of isotope radiography in industrial NDT, BARC took steps to provide a complete package including sources, exposure devices and training programmes.

• Training courses at Levels 1, 2 and 3 are provided to radiography personnel as per the procedure prescribed by the International Standards Organization (ISO – 9712) and the Bureau of Indian Standards (BIS – 13,805).
• Over 7,200 people have so far been trained in about 15 centres in the country and licensed to practice isotope radiography.
• About half of them are employed abroad, including in countries like America and Canada.
• 500 organizations/industrial plants using about 1100 exposure devises for industrial radiography. Out of these, about 350 organizations offer commercial service and others have in-house applications.
  

Lead shielded radiography camera with Ir-192 source

Fig . 1 & 2 Radiography Testing of Concrete Structures

 

Fig.3 Radiography Testing of Aircraft Engine

Fig. 4 & 5 Radiography Testing of Small Columns           

The propagation of this technique has provided many jobs opportunities, import substitute of equipment and export of isotope radiography sources.

Computerized Tomography

Schematic diagram of Industrial Tomography Setup & Tomgraphy system with 7 Ci Cs-137 source, NaI(Tl) Scintillation detector                                                                        

Tomography is a technique that produces the image of a parameter in a plane of an object without interference from the adjacent planes. When using gamma radiation, the image represents the linear attenuation coefficients of the objects for the radiation. In computed tomography, the image plane is parallel to the beam axis and image is produced by computer techniques. Industrial computed tomography (ICT) system is a breakthrough in industrial radioisotope and radiation applications since they provide a range of cross-sectional views through materials, components and assemblies . A prototype Computed Industrial Tomography Imaging System (CITIS) has been indigenously developed using 7 curies of Cs - 137 source in the BARC. The prototype unit is capable of scanning specimens of small diameters (upto 100 mm) and of varying densities.

The pictures below, give brief information about the process tomography applications being pursued.

 

Gamma Emission Tomography 

Gamma Scanning Of Industrial Process Columns

Gamma scanning technique is a very useful non- destructive and non- invasive technique for diagnosing problems in operating columns like fractional distillation, separation, stripping etc. in petroleum, petrochemical and chemical plants. This technique was initiated in India in 1995 under a MOU with the Engineers India Ltd [EIL]. Presently, BARC and EIL offer service to industry for on-line troubleshooting and process optimization of process malfunctioning in industrial process columns such as flooding, improper distribution of liquid, missing trays, etc. BARC alone has investigated over 200 columns of different type upto 9.5 diameters. This application alone has saved several hundred millions of Rupees to Indian Industry.

The conventional techniques used to identify troubles in the column such as On-line tests like pressure drop, density and viscosity measurements and simulation studies based on mathematical models and hydraulic correlations cannot pin-point the exact location of the problem.

Gamma scanning can provide information about the following:

• Location and extent of flooding
• Presence or absence of trays and other internals
• Liquid level on trays and packed column liquid distributors
• Location and severity of entrainment
• Liquid level in down comers
• Presence of liquid weeping
• Location and density characteristics of foaming
• Position of packed beds.
• Integrity of mist eliminators.
• Liquid level in reboilers, reflux drums, etc.
• Extent of liquid maldistribution in packed beds.

Apart from troubleshooting, gamma scanning can be utilized for column optimization, extending run-time of the column, predictive maintenance and scheduling shutdown. Scanning results in conjunction with simulation studies can be used to diagnose most of the column troubles and improve the design of the columns.

In the entire exercise, the interpretation of scan data is perhaps the most important step. Scanning is normally done to identify either gross abnormalities or malfunction of column subtle in nature. Gross abnormalities could be:

• Missing trays
• Collapsed trays
• Flooding of tray or down comers
• Collapsed packed bed

 

Leak detection in Heat Exchange

 

Automated Gamma Scanning System

An automated gamma scanning system useful in harsh environmental operating conditions was developed. The prototype system was designed and developed jointly by Division of Remote Handling & Robotics (DRHR) and Isotope Applications Division (IAD), BARC. Field testing of this unit was carried out on cold tower CT-1 of unit number 2 at Heavy Water Plant (HWP), Manuguru. The tower is about 4.5 meters in diameter and 54 meters height. 60Co source of about 180 mCi strength was used output. A typical line diagram of the unit is shown here.

 

 

• Nucleonic Control Systems

Devices incorporating radioisotopes such as 60Co, 137Cs, 204Tl, 90Sr, 147Pm, 85Kr, 241Am are used in industries as level gauges, thickness, density and composition gauges, gamma scanning, radiometry and also for the measurement and monitoring of important parameters related to various types of industrial products. Devices incorporating isotopic neutron sources ( 241Am-Be) and gamma sources ( 137Cs) are used for the measurement of moisture constant and density of soil and also for oil well exploration studies. Sources used in nucleonic gauges varies from few MBq to TBq. Oil refineries, chemical plants, oil platforms and terminals, in mining and mineral extraction industries etc. are some of the major end users. There are about 5,200 nucleonic control systems in operation in India today. In the years to come, there is bound to be a great demand for large numbers of advanced nucleonic control systems. These systems are sub-divided into 2 classes;

• Based on radiation transmission through the object
• Based on radiation scattered from the specimen.

Applications based on gamma ray /beta ray radiation transmission

• As installed thickness gauges to measure thickness of deposits in pipes and vessels.
• Detection and measurement of corrosion.
• Detection of voids
• Level measurements
• Detection of water in hydrogen transmission line
• Detection of liquid interfaces.

Radiation Processing

Radiation technology is based on the use of high-energy ionization radiations, mainly gamma rays from 60 Co and high-energy electrons from electron accelerators as a source of energy in different industrial and environmental applications.

The scientific basis of radiation technology is the reactive chemical species produced by absorbed radiation resulting in changes of chemical, physical and biological properties.

Value addition to diamonds

This property of radiation from a radioactive source or an electron accelerator is effectively used in a number of processes beneficial to the common man by way of production of high technology products or for the environmental cleanup.

The radiation technology programme in India was centred around the 60Co sources. Following is the present status of various aspects of radiation technology in India.

A 60Co radiation plant for the vulcanizations of natural rubber latex has been built and commissioned for the Rubber Board of India at Kottayam, Kerala in 1992. The current activity in the plant is about 50 kCi and it can process about 1.5 tons latex per day at a dose of 15 kGy. The following radiation chemical processes are being actively practiced using a 2 MeV electron beam accelerator.

 

Radiation processed natural polymer containing hydrogel for use as burn dressing developed in India

The research activity in India is mainly focused on “Radiation Processing of Natural Polymers for health care, environmental and industrial applications” as their molecular structure offer specific binding sites having high affinity for many toxic metal ions and dyes and this can be utilized to selectively remove toxic materials from waste streams. Natural polymers such as polysaccharides possess unique characteristics such as easy availability, biocompatibility and biodegradability.

High-energy radiation technique can be effectively used for reducing molecular weight of different polymers including natural polysaccharide such as alginate and Chitosan.

For such applications, it will be beneficial to use these polymers in the crosslinked form as hydrogels. Recently, we have been successful in developing a new method for Co 60 gamma ray induced crosslinking of Chitosan in the presence of carbon tetrachloride. A booklet on Radiation processing of polysaccharides for health care applications has been edited by Dr. M. Tamada and Dr. S. Sabharwal and published for IAEA/RCA from India.

Sewage Sludge hygienisation Facility at Vadodara

A sewage sludge hygienisation irradiator with an initial loading of 100 kCi of 60Co in Vadodra city has been operating successfully for about 13 years. At maximum design source loading of 500kCi, it has the capacity to hygienise 110 m 3/d of sewage sludge at a dose of 3 kGy. This plant, integrated in an existing municipal WTP in the city can hygienise the sludge which upon drying can provide very safe organic manure that can be straightaway applied in fields as fertilizer and soil conditioner.

If blended with suitable micronutrient and other plant supplements, it can yield a value added product, which will improve the quality of soil. This is the only operating facility of its kind in the world and is providing opportunities to many scientists to study the technology being practiced.

Radioisotope Tracers

Exact information about the spatial and temporal distribution of transported material can be obtained by mixing them with trace amounts of radionuclides and “tracing” these minute amounts of radioactive substances with radiation instruments. Two factors common to most tracer applications are the high degrees of specificity and of sensitivity that can be attained.

Radiotracers have provided the chemical industry with the most versatile research tool for studying the mechanism and kinetics of chemical reactions, catalysis, adsorption and absorption, chemical exchange, solvent extraction, and polymerization, dissolution, oxidation, reduction, etc. Industries benefited from the use of radiotracers include the coal, oil, natural gas, petrochemical, cement, glass, rubber, building materials, ore processing, pulp and paper, iron and steel, non-ferrous metals, and automotive industries. The major areas where tracers are used are:

Experimental set up for flow rate measurements

Radioisotope tracers are extensively used in industry for troubleshooting in process systems and components and also for characterization of flow processes in industrial systems. Leak detection and blockage location in buried pipelines and Residence Time Distribution (RTD) in process systems are typical examples. In India, these have been used in petrochemical, chemical, steel, aluminum and cement industries.

 

Radiotracer for Inter-Well Study in Oil Fields

Leak Location in Underground Pipelines : More than 20 such investigations carried out in India

  Schematic of leak detection

 Many new investigations of complex industrial processes have been recently carried which include investigation of Fluidized Catalytic Cracking Units and Coal gasifier and validation of Computational Fluid Dyanamics [CFD] models using radiotracers.

  

Radiotracer Techniques for Investigations in Fluid Catalytic Cracking Units

• Visbreaking process in petroleum refining is used to lower the viscosity of the residues by thermal cracking the feed stock at high temperature in the furnace for longer residence times.
• • Requirements;
• • Estimation of radial and axial gas hold up by grid scanning tomography and RTD study.
• • Gas hold up measurements were carried out in fan beam mode at 3 axial locations detector positions using 50 mCi Collimated Cobalt – 60 source and Nal based detector system
• • Grid tomographic scanning w successfully employed to measure chordal holdup and build up radial profiles of gas phase in industrial scale visbreaker unit. The study helped to estimate the coking formation, the extent of back mixing and its temperature dependenc y

New Requirement based on Technology Development/Modification - Need to Modify Existing Leak Location Techniques to Save Time

Trickle Bed Reactors

Design and development of Trickle Bed Reactor for Residence time distribution study of gas and liquid phases at different operating temperatures and pressures and the associated accessories such as portable grid scanning industrial tomographic scanning system for a trickle bed reactor carried out.

 

Interaction with IAEA- RCA

BARC is the Thematic Sector Lead Country for IAEA/ RCA programmes on Industry since 2001. BARC has been providing strong support to the IAEA/RCA/UNDP projects on industrial applications of isotopes and radiation technology since 1982.

 

• Has provided experts to many countries like Algeria, Bangladesh, Korea, Jordan, Thailand, Sri Lanka, Philippines, Indonesia, Mongolia, Vietnam,
• Gamma scanning set up and a radiation counting equipment and data acquisition system have been supplied to Sri Lanka as a part of a IAEA project.
• IAEA/RCA training course on “Radiotracers and Sealed Sources in Industry” (6 Nos). At the request of IAEA
• IAEA Fellowships ( Algeria, Bangladesh, Korea, Vietnam, Sri Lanka)

Promotion of Applications of Radioisotopes: The Agencies involved

• Isotope Applications Division, BARC
• Board of Radiations and Isotope Technology (BRIT)
• Board of Research in Nuclear Sciences (BRNS), DAE
• National Association for Applications of Radioisotope and
• Radiations in Industry (NAARRI)
• Indian Nuclear Society (INS)

The facilities available

• Three nuclear reactors for production of various radioisotopes

(More than 110 DIFFERENT RADIOISOTOPES)

• Radioisotope processing laboratories to process the irradiate target material into a desired form for different applications
• Facilities for packing and safe transport of radioisotopes to user locations
• Nuclear instruments and data acquisition systems
• Softwares for data interpretation and analysis
• Trained and skilled manpower
• Health and safety supervisory bodies to look after radiation safety aspects
• Regulatory bodies for licensing and radiation protection
• Over 400 large scale investigations carried out in indian industry