Atomic Energy Authority

Atomic Energy Authority (AEA) is a Sri Lankan government body for atomic energy related services which was established in1969 under act no 19. The main purposes of the Atomic Energy Authority establishment is utilization of ionizing radiation and nuclear technology for wellbeing of human, development of the Sri Lanka and creates the policies for related area and govern them. Also AEA coordinates with International Atomic Energy Agency (IAEA) for Sri Lanka which is situated in Austria.

Services of Atomic Energy Authority

  1. Radiation Protection Service
  2. Radiological Emergency Response service
  3. Nuclear Instruments repairing and maintenance service
  4. Nuclear instrument calibration
  5. Nuclear analysis service
  6. Nondestructive Testing service
  7. Isotope Hydrology service
  8. Radiation processing service
  9. Train new human resource for nuclear science area.

AEA is subdivided into several divisions to accomplish above mentioned services and following divisions are the places that can have above services.

  1. Radiation Protection Division

Ionizing Radiation is used in medical science, industrial purposes, experimental and educational purposes for various levels. Ionizing radiation should use under the protective methods because exposing to the ionizing radiation is harmful to the human body and there should be rules and regulations to control and maintain the methodology for protection standards. Radiation Protection Division’s responsibility is certifying the radiation works are going according to the standard level. This division offer following services to the public.

  • Testing the institutions for radiation protection which are using radioactive material, radioactive sources and X-ray machines and issue the insurance for radiation protection to institutions which are maintaining the acceptable limits.
  • Advising for construction of radiation rooms and issues the permission.
  • Advising for radioactive disposals.
  • Supervision of X-ray machine export and import procedure and issues the permits and etc.
  1. General scientific division

The main duty of this division is calibration of the radiation detectors which are using to measure the radiation level of people and places. To fulfill this target they are maintaining the radiometry laboratory and it increases the quality of the service of radioactive instruments. To measure the person radiation dose levels who are engaged with radioactive duties, AEA conducts the test and use the thermo luminescence dosimeters for the testing purpose.

All the analyzing parts are conducting using the computer and information technology to maintain the quality and adherence of the test.

  1. Life Science division

The main purpose of this division is conducting the nuclear analysis in more effective way and issue results to comply with international standards. Also they have training programme for university students. To conduct above tests AEA owns a fully facilitated testing laboratory. XRF analysis, TXRF analysis, gamma spectroscopy, alpha radiation measurements are done by this laboratory.

There are several services which are offered by AEA using above mentioned tests and the services of Life science division is as follows.

  • Measure the radioactivity of foods and issues the certificates (ex: Milk powder, canned fish, etc.)
  • Measure the radioactivity in environment.
  • Identify the diseases through the bio chemical samples and check the connection to the disease.
  • Analyze the metals, alloys and their painting.
  • Study about ocean environment systems and help to protect the environment and etc.
  1. Isotope Hydrology Section

The tests are doing by analyzing the composition of hydro molecules and help to identify following things,

  1. Identifying source area of the water
  2. Analyzing the activity of ground water
  3. Identifying the relationship between surface water and ground water
  4. Identifying ground water pollutant

Here Tritium duty of water is analyzed in liquid water isotope analyzer. Also this is used to identify the leaks of the dam. This has been used to identify the water entering area of leak of Smanalawewa Dam.

National Center for Non Destructive Testing (NCNDT)

Nondestructive tests are used to test and analyze materials, components for flaws in their structure without damaging. This technology is used to identify the defects of the products. NCNDT is carrying out following services,

  • Training of NDT Personnel.
  • NDT Inspection Services.
  • Certification of NDT Personnel.
  • Industrial Training

Five basic NDT methods are commonly used to examine materials. Those are,

  1. Radiographic Testing (RT)
  2. Eddy Current Testing (ET)
  3. Ultrasonic Testing (UT)
  4. Liquid Penetrant Testing (PT)
  5. Magnetic Particle Testing (MT)

Radiographic Testing (RT)

RT test is used to detect internal discontinuities in many different materials and configurations. This method is used on wide variety of products such as forging, casting and welded joints. RT is method of inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation to penetrate various materials. The intensity of the radiation that penetrates and passes through the material is either captured by a radiation sensitive film (Film Radiography) or by a planer array of radiation sensitive sensors (Real-time Radiography).

Eddy Current Testing (ET)

Eddy current test is used to detection of surface discontinuities in products which is made from conductive materials. In eddy current testing a circular coil carrying current is placed in proximity to the test specimen. The alternating current in the coil generates changing magnetic field which interacts with test specimen and generates eddy current. Variations in the phase and magnitude of these eddy currents can be monitored using a second receiver coil, or by measuring changes to the current flowing in the primary excitation coil. Variations in the electrical conductivity or magnetic permeability of the test object, or the presence of any flaws, will cause a change in eddy current and a corresponding change in the phase and amplitude of the measured current.

Ultrasonic Testing (UT)

UT can be used to detection of internal discontinuities of materials. By using this method even small defect can be identified precisely. Also this method can be used for thickness measurement.

Liquid Penetrant Testing (PT)

Liquid penetrant inspection is a method that is used to reveal surface breaking flaws by bleed out of a colored or fluorescent dye from the flaw.  The technique is based on the ability of a liquid to be drawn into a clean surface breaking flaw by capillary action. Following steps are following in this testing.

  • Surface Preparation – Surface should be clean before the test and he surface must be free of oil, grease, water, or other contaminants that may prevent penetrant from entering flaws.
  • Penetrant Application – After the surface has been thoroughly cleaned and dried, the penetrant material is applied by spraying, brushing, or immersing the part in a penetrant bath.
  • Penetrant Dwell – The penetrant is left on the surface for a sufficient time to allow as much penetrant as possible to be drawn from or to seep into a defect.
  • Excess Penetrant Removal – Excess penetrant must be removed from the surface of the sample while removing as little penetrant as possible from defects.
  • Developer Application – A thin layer of developer is then applied to the sample to draw penetrant trapped in flaws back to the surface where it will be visible.
  • Inspection – Inspection is then performed under appropriate lighting to detect indications from any flaws which may be present.
  • Clean Surface – Clean the part surface to remove the developer from the parts

Magnetic Particle Testing (MT)

Magnetic particle testing is used to detection of surface and sub-surface discontinuities of the product which are made from ferromagnetic materials. The first step in a magnetic particle inspection is to magnetize the component that is to be inspected. If any defects on or near the surface are present, the defects will create a leakage field. After the component has been magnetized, iron particles, either in a dry or wet suspended form, are applied to the surface of the magnetized part. The particles will be attracted and cluster at the flux leakage fields, thus forming a visible indication that the inspector can detect.

Non-Destructive Testing for Concrete Structures

Nondestructive testing is used to check the quality of concrete structures. Quality and the strength of the concrete structures should be monitored without destruction. A large variety of NDT methods are available now in the testing laboratory of the NCNDT.

  • Ultrasonic Pulse Velocity Detector

Ultrasonic Pulse Velocity Machine can measure the transit time and pulse velocity, path length, perpendicular crack depth measurement and compressive strength estimation.

  • Rebound Hammer Tester

The Rebound or Schmidt Hammer Tester can analyze the uniformity and compressive strength characteristics of existing concrete structures.

  • Pull Off Tester

The full off tester can determine the adhesive strength of applied coating and the tensile strength of concrete

  • Reinforcement Detector

The reinforcement detection meter can measure the location and orientation of rebar, concrete cover and rebar diameter.

  • Impact Echo Tester

The Impact Echo tester can determine the location and extent of flaws, cracks, de-laminations, voids, honeycombing and de-bonding in plain, reinforcement concrete structures and can measure the thickness of concrete slap or plate.

  • Corrosion Detector

The corrosion analysis detector can measure corrosion potentials and resistivity conditions of the steel in concrete to measure the rate or corrosion.

Sri Lanka Gamma Center (SLGC)

This is the first multi-purpose gamma irradiation facility in Sri Lanka which is situated at Biyagama Export Processing Zone. SLGC is Designed to give activity of the radioactive source is 3000 kCi. Initial Activity of the radioactive source was 250 kCi and the Current Activity of the radioactive source is 201 kCi.

To have radioactive part, Co-60 pencils are used as the source. This radiation source must keep within a protected storage. Therefore radiation source is fully shield by a thick concrete shell. The thickness of the concrete above ground level is almost 2m. The radiation source is submerged in water in an underground storage pool and can be lifted by the source rack. Irradiation occurs when the products are exposed to the radiation source which is lifted above its storage pool.

The one of use is food and here products are entered into the chamber using conveyors. Each product circulates two times inside the chamber. At the second round product holding box is rotated to achieve same radiation levels for each product. A dosimeter is inserted in to some boxes and they are check in the dosimetric laboratory. After checking the products are exposed to the required level of radiation, quality of the process can be assured.

Gamma Processing Cycle

There are several protection schemes are available for radiation storage. Before lifting the source the operator should go inside the chamber and push series of buttons which is forcing him to observe the whole chamber. Each time entering to the chamber radiation detector should be carried and at the entrance there is a check source to check whether the meter is working correctly. And the main opening is interlocked with the source. No one can enter when the source is lifted.

Irradiation can be used for following applications,

  • Microbial decontamination of foods
  • Germination Inhibition
  • As a quarantine treatment
  • Sterilization of packaging materials
  • Extend the shelf life of the products

Sterilizing of medical products with gamma rays is one of the most important application of irradiation process. Latex gloves which are exported as un-sterile examination gloves can be exported as sterile surgical gloves, with a very high value addition and is estimated as at least by 400%. Medical supplies such as syringes, catheters, sterile dressing and saline are also sterilized. Human tissue sterilizing is also another application.

This plant can be also used for food preservation. The production and the use of methyl bromide which is widely used for fumigation of export products including spices, is being phased out and can affect the export trade. Gamma irradiation is a good alternative for that.

Benefits of gamma irradiation

  • No recontamination
  • Non toxic
  • No chemical residues
  • Easy to control process
  • Environmentally friendly
  • Low-Temperature process
  • Ability of handling just after the process

References