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APPLICATIONS OF RADIOTRACERS AND NUCLEONIC CONTROL SYSTEMS IN

INDUSTRY AND ENVIRONMENT

BACKGROUND

Stimulated by an ever increasing demand from large production plants, many radioisotope techniques have

been evolved to provide fast and effective solutions to plant and process problems. Relevant target areas for

radioisotope applications are well defined. Though the technology is applicable across a broad industrial

spectrum, the petroleum and petrochemical industries, mineral processing and wastewater treatment sectors are identified as the most appropriate target beneficiaries of radioisotope applications: these industries are

widespread internationally and are of considerable economic and environmental importance.

Radiotracer technology is used to diagnose specific causes of inefficiency in plant or process operation. The

troubleshooting derives benefits in the form of savings associated with plant shutdown minimization and loss

prevention. While a troubleshooting project results in a “one-off” economic benefit, often realized as savings, an optimization exercise results in a permanent and ongoing increase in productivity and/or product quality,

leading in turn to a continuing increase in profit. Thus, the cost: benefit ratio from process optimization

application is likely to be considerably greater than for troubleshooting.

Nucleonic control systems (NCS) or Nucleonic gauges are nuclear instruments for measurement and analysis

based on the interaction between ionizing radiation and matter. NCS technology is by far one of the most

requested among other industrial radioisotope techniques. NCS have been widely used by various industries to improve the quality of product, optimize processes, and save energy and materials. The magnitude of the

benefit obviously varies from one application to another, but is always considerably greater than the costs of

purchasing, installing and maintaining the instrument.

Industrial process gamma tomography is being developed for the study of multiphase processes. Multiphase

reactor technology is the basis of petroleum refining, synthesis gas conversion to fuels and chemicals, bulk

commodity chemicals production, manufacture of specially chemicals and polymers, and conversion of undesired products into recyclable materials. While progress has been made in understanding fundamental

reaction mechanisms and in computing the effect of mass transfer on the reaction rate locally, the description

of the reactor scale flow pattern and mixing is in general primitive and rests on the assumption of ideal flow patterns. Radioisotope techniques help optimising multiphase reactors saving billions of US dollars annually

in world scale.

APPLICATION OF RADIOTRACER FOR OPTIMISATION AND TROUBLESHOOTING IN

PROCESS INDUSTRIES – THE RESIDENCE TIME DISTRIBUTION (RTD) APPROACH.

Residence time distribution (RTD) measured by radiotracers has become an important tool for the diagnosis of

industrial processing units (Figure below). Among the large variety of tracers, radioisotopes have very unique advantages: specificity, selectivity and low detection limit.

Principle of RTD method

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The major targets for applications of radiotracer technology are:

a. Petroleum industry

The applications of radioisotope technology are widespread throughout oil refineries worldwide and this

industry is one of the main users, and beneficiaries of the technology. Economically, the most important operating unit in a refinery is the Fluidized Catalytic Cracking Unit (FCCU), the function of which is to

upgrade the “heavy” components of the oil to gasoline. Technically, this is also the most complex unit,

involving as it does the interaction of multiple phases: solid catalyst, vaporized feedstock steam and air. Because of the construction and extreme operating conditions of FCCUs, the only effective way to diagnose

their behavior is through the application of radiotracers.

b. Petrochemical complexes

Like refineries, petrochemicals plants are generally continuously operating and technically complex. Though

radiotracers are useful in solving a wide range of problems, the economic benefits become more pronounced

the further “upstream” they are applied. This means that diagnosis of the cracking furnace, primary fractionator and gas separation chain is of the highest potential value.

c. Minerals processing This generic heading covers an enormous range of industries. Minerals processing plants, in one form or

another are to be found in practically every country in the world and in many cases they are major contributors

to national economies. Though the range of minerals which are extracted and processed is extremely wide, there are certain processes found throughout the industry, such as comminution, classification, flotation and

homogenization.

RTD modeling of grinding mills and flotation cells

d. Hydraulic detention times in wastewater treatment ponds

RTD method has proved to be a cost-effective monitoring technique, providing an insight into many areas of

water quality, sludge behavior, plant process and outfall dispersal. The results have enabled to identify areas

where substantial savings in both capital and operational expenditure can be made. Water gamma tracers such

as Na131

I, 51

Cr-(EDTA), TcO4-,

113mIn-(EDTA),…. or

113InCl3, TcO4-(SnCl2), H

198AuCl4-, … for tracing solid

phase can be used depending on the size of the pond when in situ measurement extends over hours, days or

even weeks.

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RTD investigation of a wastewater purification installation

Classical applications, such as residence time distribution (RTD) measurements for troubleshooting, have

been well mastered and the use of radiotracers has by now spread to all the branches of chemical engineering.

However, constant progress in hardware (new detectors and data acquisition systems) and software (user friendly simulation and image creation codes) allow considering new advances in the radioisotope

methodology and technology. For instance, the use of computational fluid dynamics (CFD) and gamma

computer tomography (CT) begun to appear in chemical engineering literature several years ago.

At the present time, CFD simulation constitutes an interesting tool for the visualization of flows in reactors.

Nevertheless, physical relevance of CFD calculation can be questionable especially when hydrodynamics and

physico-chemical interactions are coupled. Then, it seems natural to compare CFD models and the systemic RTD approach based on experimental results provided that this comparison could lead to the validation of

both methods. There are efforts to elaborate a combined RTD-CFD experimental-computational method for

obtaining reliable quantitative results about process insight in industrial vessels and process units to improve and optimize their design and efficiency.

Verification of the CFD simulation with tracer RTD experimental results

The number of radiotracer services for troubleshooting inspections carried out per year is in excess of tens of

thousands, worldwide. Still many radiotracer services, in particular in developing countries without nuclear

reactor, are not provided lack of timely availability of radioisotopes. Medical radionuclide generators such as 99

Mo/99m

Tc and 113

Sn/113m

In have limited applicability in industrial and environmental mediums due to their

relatively short shelf-lives and low gamma energy. In this context, the commercial development of the Ge-

68/Ga generator is of particular interest. The half-life of the parent, Ge-68, is 258 days, so that the generator may be used for more than one year. The half-life of the Ga-68 daughter is only 68 minutes, which is adequate

for many studies. The Ga-68 also has a high-energy gamma-ray of 1.08 MeV so that the tracer can be detected

from outside of operational vessels and pipes. In addition, Ga-68 is a positron emitter and may be used as a tracer for positron emission tomography.

0

0.0005

0.001

0.0015

0.002

0.0025

0 200 400 600 800 1000 1200 1400

Temps (s)

DT

S (

s-1

)

Experiment

CFD model

Systemic model

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APPLICATION OF NUCLEONIC CONTROL SYSTEMS

Simple nucleonic control systems (NCS) or nucleonic gauges first began to be used in industry over forty years ago. Since then, there has been a continuous expansion in their usage. The competition from alternative

methods shows that NCS have survived and prospered in the past because of their superiority in certain areas

to conventional methods. The success of NCS is due primarily to the ability, conferred by their unique

properties, to collect data, which cannot be obtained by other investigative techniques.

Scheme of nucleonic control system (nucleonic gauge)

Spectre of nucleonic gauges worldwide

Many NCS are now commercially available from several manufacturers. Nevertheless, significant types of

NCS are not in the realm of commercially available services. The development of supporting technologies

such as compact electronics, fast computers, high-resolution detectors, small reliable neutron tubes, and

dedicated computer modeling codes has resulted in increased technical viability and economic acceptability of NCS.

There are several ways of applying nucleonic gauges, among them: � On-line process (NCS): density, thickness, level, concentration, elemental analysis,

� Off-line process (bulk sampling): coal and mineral processing,

� In-situ (well logging) : mining for coal and minerals,

� Used in laboratory (on samples): elemental analysis, coal ash, moisture, � Portable, for site measurements: thickness, blockage, corrosion, density, moisture, etc.

To date two commercially successful on-line analyzers are the mineral slurry analysis systems and the coal ash analyzers. The accurate on-belt determination of ash in coal is required in a wide range of applications in

the coal industry, including mine grade control, raw coal monitoring, coal sorting, coal preparation plant

control, product blending, stockpile management, power station feed, and monitoring at coal shipping ports.

The economic benefit gained from improved control based on use of these instrument systems often pays for

the cost of the on-line analysis system in 3-9 months following installation.

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Online coal ash analyser based on dual energy gamma-ray transmission

Prompt gamma neutron activation analysis (PGNAA) using radioisotope neutron sources of 252Cf or 241Am-Be

is largely applied for online coal ash, mineral slurry and cement raw material analysis in modern industry. The

PGNAA cross-belt analyzer is a precise on-line multielemental analyzer for bulk materials. The PGNAA is

recently used for borehole logging as well.

PGNAA method used for borehole logging in copper mining

Some examples of nucleonic measurement and control systems

Paper Thickness Mineral Industry Coating

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Gas measurement Dust monitoring

Level gauges

Examples of nucleonic measurement systems in industry

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APPLICATIONS OF SEALED SOURCES

GAMMA SCANNING OF COLUMNS, VESSELS AND PIPES

Gamma Scanning is the best technique to carry out an internal inspection of any process equipment, without

interrupting production. A collimated beam of penetrating gamma rays is allowed to pass through the shell of

a vessel, gets modified by the vessel internals and then coms out of the other side.By measuring the intensity of the transmitted radiation, valuable information can be obtained about the densities of the materials present

inside the vessel. The higher the density of the material, the less radiation gets through; so significantly more

gamma rays are transmitted through a vapour compared to a liquid phase.

Principle of gamma scanning profile

Density scanning of distillation columns is the most commonly used application of this technique. Without

affecting processing unit, this reliable and accurate technique can be used to determine:

The liquid level on trays

• The presence or absence of internals, such as trays, demister pads, packing and distributors

• The extent and position of jet and liquid stack flooding

• The position, and the density characteristics of foaming

Gamma ray source and radiation detectors are moved simultaneously down opposite sides of the column. The

intensity is recorded at appropriate intervals and a profile of the instantaneous operating state is obtained by plotting the detector response against the column elevation. The tray structure and the liquid on the trays give

high absorption, while the presence of foam and entrainment slightly moderates the expected vapour profile.

Studies of the degree of foaming can be carried out by generating density profiles at different concentrations of antifoam additive. The scanning of pipelines for blockages or build-up is another excellent use of Gamma

Scanning because it is faster and uses lower radiation levels than conventional X-ray techniques.

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Performing gamma scanning of distillation column in petroleum refinery

LEVEL AND INTERFACE DETECTION BY NEUTRON BACKSCATTER GAUGE:

Neutron backscatter level measurement gauge can detect interfaces between solids, liquids and vapour to an

accuracy of 1”. Vessels can be almost any diameter, with wall thickness up to several inches. The detection

equipment is external to the vessel so these measurements are applicable to any process material -whether it is

toxic, corrosive, or viscous, and at any temperature or pressure. These techniques even permit calibration of installed level gauges.

Without affecting the process reliable, accurate measurement techniques can:

• Determine liquid and sludge levels in storage vessels

• Locate water/organic Interfaces

• Measure foam levels

• Determine absorption tower packing levels

• Calibrate level gauges quickly and easily

Solid/liquid and liquid/liquid interfaces are best detected using Neutron Backscatter technique. High energy or

"fast" neutrons from a radioactive source are beamed into the vessel and slowed down by collision with hydrogen atoms in the process material. A direct hit results in a slow neutron being bounced back towards the

source. By placing a slow neutron detector next to the source, these backscattered neutrons can be measured

and are directly in proportion to the concentration of hydrogen atoms adjacent to the probe. As the source and

detector move down the side of the vessel, interfaces can be detected provided they involve a change in hydrogen atom concentration.

Neutron backscatter gauge Neutron backscatter level measurement in for level and interface measurement progress on a knock-out drum

in oil storage tanks

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VISUALISATION TECHNOLOGY

Industrial process gamma tomography is recently become popular in many laboratories. Gamma Computer Tomography (GCT) technique is the most suitable for visualization of process inside the opaque multiphase

equipments. There are two gamma GCT methods:

Gamma Transmission Tomography: Gamma transmission tomographic technique is based on the assumption that there is heterogeneity of a parameter in the system under investigation. In general this parameter is the

density of the medium, for example the density of a packed bed or the concentration of a phase in a dual phase

flow. There are many geometrical arrangements of source and detector(s). The simplest of these is the parallel, or pencil beam, configuration in which a source, emitting a single pencil beam of radiation is coupled to a

radiation detector.

To obtain a single view, the source and detector (placed on opposite sides of the test specimen) are moved

parallel to one another to measure the attenuation across the specimen at a number of positions. For the next

view, the detector-source arrangement rotates about the test section and the translation is repeated. In process

engineering, gamma transmission tomographic applications consist mainly of the inspection of packed columns, bubble columns, fluidized beds and porous media.

Gamma transmission CT with 1 S – 1 D and pencil beam scanning; wood image

More complex system are also existing with 1 source – some detectors, 1 source – 1 imaging device such as a

flat panel, X-ray generator instead of radioactive source, some sources – many detectors without movement, etc… The configuration is depending upon the objectives in terms of space and time resolution.

CT system with 1

137Cs source and

32NaI(Tl) detectors (from CEA)

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CT system with flat panel (from Dürr Cie)

Gamma Emission Tomography (SPECT): To investigate flow dynamics in multiphase flows, with or without density variations, it is generally better to use radioactive tracer, labeling one phase and observing the

behavior of this phase in the flow. Measuring radiotracer gamma radiation in a tomographic configuration the

visualization of the flow patterns inside vessels becomes possible.

Gamma emission CT: 36 small NaI detectors Flow construction inside the pipe

around the pipe radiotracer Tc-99m, (from CEA- France)

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APPLICATION OF RADIOTRACER TECHNIQUES FOR INTERWELL STUDIES

Tracer applications can be found in almost any stage of the oil field development. Interwell tracer technology

(IWTT) is an important reservoir engineering tool for secondary and tertiary recovery of oil. Interwell tracer

test is also used in geothermal reservoirs to get better understanding of reservoir geology and to optimize

production and re-injection program. The main purpose of interwell tracer tests in oil and geothermal reservoirs is to monitor qualitatively and quantitatively the injected fluid connections between injection and

production wells and to map the flow field, reservoir heterogeneities and volumetric sweep (contacted

volumes) between wells.

Tracer is added into injection fluid via an injection well and observed in the surrounding production

wells.Tracer response is then used to describe the flow pattern and obtain better understanding of the reservoir. This is important knowledge in order to optimize the oil recovery. Most of the information given by

the tracer response curves cannot be obtained by means of other techniques.

Principle of tracer injection method for interwell communications

Fluid flow in most reservoirs is anisotropic. The reservoir structures are usually layered and frequently contain significant heterogeneities leading to directional variations in the extent of flow. Hence, the effective fluid

movement can be difficult to predict. Here is where tracer technology plays an important role assuming that

the movement of the tracer reflects the movement of the injected fluid.

Obviously, it is most important to assure that the properties of the tracer meet this requirement as closely as

possible: There should be a minimum amount of undesired loss or delay. The physical and geochemical

conditions of the reservoir define the constraints. As a result, tracers found to work properly in one reservoir, may not work to satisfaction in another.

Interwell tracer technology in oilfield

The efficiency of the water flooding process is highly dependent on the rock and fluid characteristics. In

general, it will be less efficient if heterogeneities are present in the reservoir, such as permeability barriers or

high permeability channels that impede an efficient volumetric sweep and thereby a good oil displacement by the injected water.

Natural production mechanisms, or primary production, contribute to extract from the reservoir about 25% of the original oil in place. This means that 75% of the existing oil remains in the pores and fissures of the rocks.

The production flow rate depends on the differential pressure between the permeable layer and the bottom of

the well, the average permeability, the layer thickness and the oil viscosity. The main natural production

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mechanisms are the expansion of the oil, water and gas and in certain cases the water influx from aquifers

connected with the reservoir.

When primary oil production decreases in a field because of a reduction in the original pressure, water is

usually injected to increase the oil production. Injected water in special wells (injection wells) forces the oil

remaining in certain layers to emerge from other wells (production wells) surrounding the injector. This technique, commonly called secondary recovery, contributes to extract up to 50% of the original oil in place.

Although this technique was firstly used in old reservoirs in which oil production had decreased, it is today a

common practice to begin the exploitation of new wells with fluid injection as a way to optimize oil recovery. For this reason, the name secondary recovery is being replaced by the more general term “Enhanced Oil

Recovery (EOR)”.

For oil reservoirs interwell tracer data are important in order to optimize the production strategy (injection

balance) in the reservoir and thereby maximize the oil recovery. In geothermal reservoirs interwell tracer tests

are used to improve the understanding of reservoir geology and to optimize production and re-injection

programs and thereby the enthalpy production from the reservoir. During the last 10-15 years there has been substantial progress on tracer technology development. This has resulted in new basic knowledge and new

technology.

Detailed analysis of the response curves obtained from interwell studies allows to:

� detect high permeability channels, barriers and fractures, � detect communications between layers,

� evaluate the fraction of the injection water reaching each production well,

� determine residence time distributions,

� indicate different stratifications in the same layer, � determine preferential flow directions in the reservoir,

� determine swept volume of the reservoir.

All this information can be used to make operational water flooding decisions in order to increase oil

production.

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APPLICATIONS OF RADIOACTIVE TRACERS IN THE REAL-TIME MEASUREMENT OF

WEAR AND CORROSION

Radioactive tracer technology has been used for many years as a tool to make highly sensitive real-time

measurements of wear and corrosion. With this technique, the material of interest is tagged with radioactive

isotopes through either direct activation (Thin layer activation- TLA) of a relatively small number of atoms in the component itself, or implantation of radioactive isotopes. As the component wears or corrodes under test,

radioactive atoms are transported from the surface in the form of wear particles or corrosion products. Wear or

corrosion is measured in real-time through either interrogation of the buildup of radioactivity in the transport fluid, or by the reduction in activity of the labeled wear component. The process involves selection of an

appropriate labeling technique, labeling of a component or components of interest, calibration, testing and

data reduction and analysis

Thin Layer Activation technique for monitoring wear and corrosion in industry

Thin Layer Activation (TLA) is a very competitive technique for non-invasive, on-line measurement of wear, erosion and corrosion. Its very high sensitivity allows low cost measurement minimizing the testing time on

testing benches for engines, weapons, tribologic machines, etc…

12 MeV protons accelerated by a tandem accelerator (or cyclotron) are fired into a steel component (coupon)

to produce the radioisotope Co-56 within the surface thin layer (230 µm). Activated radioisotope Co-56

decays back to Fe-56 emitting gamma rays. The level of radioactivity remaining provides the loss of material from the surface (wear and corrosion). The method has been applied in the car, petrochemical and pulp

industries (where corrosion is high and dangerous). When the component under investigation is too large, a

representative coupon of the same material is irradiated and then attached to the exposed surface. The

sensivity of the TLA technique is 1% of the maximum implant depth (2,3 µm in our case).

Coupon activation with Tandem accelerator Wear measurement on a car engine

Thyn Layer Activation (TLA) technique has many applications; although the majority of the work performed

has been in the automotive engine and lubricant industry, recently it has extended the application into other fields, such as hydraulic pump wear, prosthetic hip joint wear, wear in marine engines and crude oil

corrosivity.

TLA techiques was promoted and implemented to several RCA MS through the IAEA TC projects. Fig. 22

shows application of Thin Layer Activation (TLA) technique for monitoring wear and corrosion in oil pipe in

Thailand and Pakistan.

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Efficiency studies of additives in lubricant on a tribologic test bench

Thin Layer Activation (TLA) technique for monitoring wear and corrosion in oil pipe in Thailand and

Pakistan

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RADIATION TECHNOLOGIES FOR INVESTIGATION OF SEDIMENT TRANSPORT

The investigation of sediment transport in sea and rivers is crucial for civil engineering and littoral protection and management. Radioactive methods, radiotracers, natural radioactivity, sealed sources and nucleonic

gauges can help in investigating sediment dynamics providing important parameters for better designing,

maintaining and optimizing civil engineering structures and objects in these areas.

Typical sediment transport problems are:

• Littorals in many countries are subjected to erosion, and shorelines undergo long-term retreat, which

often leads to beach loss,

• For the management of sufficient water depth at ports and harbors to accommodate ship movements,

dredging operations are carried out. The selection of suitable dumping site of dredged material is very important, as dumped material should not come back into the navigation channel.

• Improper selection of a dumping site for dredging operation at harbours may cause return of dumped

material to dredged channel.

Radiotracer sediments can be produced:

• By surface deposit (for sand) or mass labelling (for mud) of a radioisotope (198

Au, 51

Cr, 181

Hf, ) on

sediments by means of chemical reactions;

• By simulation with glass crushed of the same density and granulometry, therefore having the same behaviour in water as natural sediments, but containing activable isotopes becoming radiosotopes in nuclear

reactor (198

Au, 192

Ir, 46

Sc).

The figure bellow illustrates a typical bed-load sediment transport using radiotracers injected on the sea

bottom surface.

Sketch of data acquisition System for sediment transport / pollutant tracing studies in Coastal area

Tracer technology complements more traditional methods (current metering, turbidity measurements and modelling) and is the only unequivocal method of direct assessment of sediment transport pathways. Tracers

include radiotracers and conventional tracers, mostly fluorescent tracers. Radioactive tracers are more

sensitive and provides more qualitative and quantitative parameters than conventional tracers.

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In addition to radiotracers, radiation based instruments (namely nucleonic gauges or nucleonic control and

measurement systems) can provide: • density of the sediments deposited in a channel of navigation;

• concentration of sediments circulating in suspension.

Radiotracer and sealed source techniques are very useful and often irreplaceable tools for sediment transport studies. The dynamic sedimentology, formerly descriptive science, became a branch of the mechanics of the

fluids thanks to the use of the radioactivity.

Gamma back-scattering gauge for turbidity monitoring JTD3

JTD3 is a gamma back-scattering gauge for field measurement of high concentration of sediments deposited in harbors, navigation channels, dam reservoirs and rivers. The radioactive source is Cesium-137 with activity

of 18.5 MBq (0.5 mCi) and the detector NaI(Tl) scintillator 12x24 mm. It weights 20 kg. The range of

measurement is 30-800 g/l.

JTD3 turbidity gauge; the gauge (left) and measuring vertical profiles of density of mud deposits in harbour

basins (right) or dam reservoirs

Gamma transmission gauge for turbidity monitoring of mud layer JTT4

JTT4 is a gamma transmission gauge for continuous measurement of the density and depth of mud layer in

harbor navigation channels. The gauge sits on a sledge, which is dragged by a boat. It is an indispensable

supplement to ultrasonic device (which gives only the position of the “top” of the layer and that of hard bottom). It helps optimizing dredging work. JTT4 has a

137Cs source with activity of 222 MBq (6 mCi) and a

detector of NaI (Tl) scintillator of 24 x 36 mm. The source detector clearance (where the layer of muddy water

circulates) is 20 cm. It weights 114 kg because is designed to move on the bottom of sea, river or dam. The

range of concentration measurement is 1 to 300 g/l.

JTT4 turbidity transmission gauge

SEDITRACKER G60 gamma transmission gauge

The SEDITRACKER gamma transmission gauge is designed to respond the needs to measure the sediment

concentration in natural environments. There are two operational methods:

• measuring the sediment density versus time in a fix position, • measuring the vertical profile of the sediment concentration in a fix position and nearly fix time.

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The first operational method (Eulerien) gives the sediment concentration versus time. The quantity of transported sediments in a period of time can be calculated knowing the liquid flow rate. The deposed

sediment in a dam reservoir can be estimated from monitoring the solid sediments entering and leaving the

dam. Monitoring of suspended sediment concentration is necessary for better dam management, in particular

in semi-aride zones or zones with high soil erosion. In such an operational mode the SEDITRACKER has similar function like JTD3 gauge.

The advantages of the SEDITRACKER gauge to JTT4 (gamma transmission) and JTD3 (gamma scattering) are:

- JTD3 has a moderate weight of 20 kg and moderate sensitivity; it works only for vertical profiling of density

(only one function), - JTT4 has a heavy weight of 114 kg and high sensitivity; it provides mud concentration profile that means the

nonconsolidated mud layer above the compact bottom.

- SEDITRACKER has a moderate weight and an improved sensitivity; it combines all operational functions of

JTD3 and JTT4. - SEDITRACKER is an intelligent gauge; it has in addition a very small

241Am source (1 µCi) for internal

calibration.

View of SEDITRACKER G60 in calibration process in laboratory then arriving at Kinguele dam (Gabon)

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NON-DESTRUCTIVE TESTING (NDT)

Radiation Technology and complementary techniques

NDT is the science using non-invasive techniques to determine the integrity of a material, component or

structure, or quantitatively measure some characteristic of an object. The need for NDT today is even more essential than ever before. Typical industries where NDT is largely used in routine inspection include power

generation, aerospace, transport (road, rail, sea and air), oil and gas exploration, pumping, refining and

distribution, petrochemicals, heavy mechanical fabrication, electronics and defense production, civil engineering, etc…

NDT is a tool for quality. It has played a significant role in improving product quality, safety and reliability.

NDT organization shall be subjected to a quality system to ensure the quality of services provided to the client. Most NDT end users adopted some form of a quality system in their organization, e.g. ISO 9001. The

most logical quality system applicable to NDT organization is ISO 17025. Elements in this quality system

include control of documentations, qualification and certification of personnel’s, calibration of equipment, the use of written procedures, corrective and preventive action etc. These elements must be documented in the

form of a quality manual.

- Qualification and certification of NDT personnel (ISO 9712)

- Written procedures - Equipment calibration (ISO 17025)

- Accreditation of NDT personnel (ISO17024)

Some uses of NDT methods are:

- flaw detection and evaluation

- location determination - dimensional measurements

- structure and microstructure characterization

- stress (strain) and dynamic response measurements

- material sorting and chemical composition determination

NDT methods are used at almost any stage in the production or life cycle of a component:

- to assist in product development - to screen or sort incoming materials

- to monitor, improve or control manufacturing processes

- to verify proper processing such as heat treating, - to verify proper assembly

- to inspect for in-service damage

The six most common NDT basic methods are: - visual Testing (VT)

- Liquid penetrant Testing ( PT)

- Magnetic Testing (MT) - Ultrasonic Testing (UT)

- Eddy-current Testing (ET)

- Radiographic Testing (RT) which is based mainly on gamma rays from radioactive sources or X.rays

from X-ray generators. Sometimes Beta rays can also be employed.

RT still represents the largest NDT technique in the market and is generally considered to be the reference

method for all other ‘’complementary’’ techniques. Principle of radiography techniques is given on figure below, and some typical application of NDT techniques are presented.

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Principle of radiography

NDT for nuclear power plants: assuring quality for safe operation

NDT for petroleum industry - radiography of welds

radiographic Techniques applied in industry

The introduction of powerful computers and reliable imaging technology has had significant impact on the

traditional nuclear based NDT methods. In particular, digitization of images provides economy of storage, reduced radiation hazards, efficiency of communication and increased speed of execution thus resulting in

improved productivity. Digitization allows radiographic data to be analyzed using imaging and defect

detection algorithms; images can also be accessed via network and even emailed to experts for real time

evaluation and verification.

NDT laboratories in developed countries are progressing rapidly with digitalization of NDT data. New

imaging techniques using image intensifier systems, imaging plates, flat panel detectors have increased the capacity for visualization of defects and revealed new potential for accurate evaluation.

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Digital industrial radiography has the following benefits: � reduces radiation dosage and exposures resulting in less risk to the operator and less disruption to

other operations;

� reduces radiographic inspection time, and improves productivity;

� eliminates film processing chemicals, chemicals disposal and storage costs; � digital radiographs are not degradable;

� is easily customized for field radiography in a portable package;

� allows analysis using image processing and defect detection algorithms; � storage costs are minimized as all images are stored on hard discs or optical media like CD-ROMs or

DVD-RAMs. Images can also be accessed via network and even emailed to experts for real time

verification; � reusable imaging plates mean that savings can be generated as one plate can be used many times.

I Imaging Plate (from Dürr Cie) Flat panel - DDA (from Dürr Ci

Significant cost savings due to use of DIR systems have been reported by industry. With the advancement of image intensifier systems, imaging plates, flat panel detectors and fast multimedia computers, digital

industrial radiology is finding increased applications.

Beside industrial applications, RT has also a strong interest for cultural heritage:

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« Venus de Milo’’ in Louvre Museum - France

Showing central hole and metallic inserts

Gammagraphy of statutes