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7/31/2019 Report Soalan Lawatan

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1. What is a TRIGA reactor?

Reaktor TRIGA PUSPATI (RTP) the only nuclear research reactor in Malaysia. It came into

operation in 1982 and reached its first criticality on 28 June 1982. TRIGA comes from the word

Training, Research, Isotopes and General Atomics. TRIGA reactors is a class of small nuclearreactor designed and manufactured by general atomics. TRIGA is apool-type reactorthat can be

installed without a containment building, and is designed for use by scientific institutions and

universities for purposes such as undergraduate and graduate education, private commercial

research, non-destructive testing and isotope production. The TRIGA reactor uses uranium

zirconium hydride (UZrH) fuel, which has a large, prompt negative thermal coefficient of

reactivity, meaning that as the temperature of the core increases, the reactivity rapidly decreases.

The reactor was designed to effectively implement the various fields of basic nuclear science and

education. It incorporates facilities for advanced neutron and gamma radiation studies as well as

for application, including Neutron Activation Analysis (NAA), Delayed Neutron Activation

Analysis (DNA), Radioisotope Production for medical, industrial and agricultural purposes,

Neutron Radiography and Small Angle Neutron Scattering (SANS).The TRIGA reactor is another

common design (40 units). The core consists of 60-100 cylindrical fuel elements about 36 mm

diameter with aluminium cladding enclosing a mixture of uranium fuel and zirconium hydride as

moderator. It sits in a pool of water and generally uses graphite or beryllium as a reflector. This

kind of reactor can safely be pulsed to very high power levels (e.g. 25,000 MW) for fractions of a

second. Its fuel gives the TRIGA a very strong negative temperature coefficient, and the rapid

increase in power is quickly cut short by a negative reactivity effect of the hydride moderator.

2. What are the difference between the reactor for research and reactor for energy

purposes?

Reactor for research have wide range of uses including analysis and testing of materials and

production of radioisotopes. Their capabilities are applied in many fields, within the nuclear

industry as well as in fusion research, environmental science, advanced materials development,

drug design and nuclear medicine. The main purpose in research reactor is to utilize the actual
http://en.wikipedia.org/wiki/Pool-type_reactorhttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Uranium_zirconium_hydridehttp://en.wikipedia.org/wiki/Uranium_zirconium_hydridehttp://en.wikipedia.org/wiki/UZrHhttp://en.wikipedia.org/w/index.php?title=Thermal_coefficient&action=edit&redlink=1http://en.wikipedia.org/wiki/Pool-type_reactorhttp://en.wikipedia.org/wiki/Isotopehttp://en.wikipedia.org/wiki/Uranium_zirconium_hydridehttp://en.wikipedia.org/wiki/Uranium_zirconium_hydridehttp://en.wikipedia.org/wiki/UZrHhttp://en.wikipedia.org/w/index.php?title=Thermal_coefficient&action=edit&redlink=1


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neutrons produced in the core. Reactor for energy purpose such as nuclear power reactor, nuclear

reactor produces and controls the release of energy from splitting the atoms of certain elements. In

a nuclear power reactor, the energy released is used as heat to make steam to generate electricity.

In most naval reactors, steam drives a turbine directly for propulsion.

3. Prior to the fission process occurs, the thermal neutrons should be produced first. How is this

done?

A neutron of very slow speed and consequently of low energy. Their energy is of the same order as

the thermal energy of the atoms or molecules of the substance through which they are passing. For

example about 0.025 electron volts, which is equivalent to an average velocity of about 2,200

meters per second. Thermal neutrons are responsible for numerous types of nuclear reactions,

including nuclear fission. Thermal neutron can be done using neutron moderator which is a

medium that reduces the speed of fast neutrons, by turning the neutrons into thermal neutron that

capable of sustaining a nuclear chain reaction involving Uranium-235. There a few type of neutron

moderator which are regular light water type, solid graphite and heavy water. Moderation is the

process of the reduction of the initial high kinetic energy of the free neutron. The process occurs

also know as neutron slowing down process, since along with reduction of energy, the speed also

decrease. Neutron capture can occur when a neutron approaches a nucleus close enough for nuclear

forces to be effective. The neutron is captured and forms a heavier isotope of the capturing

element. When the new isotope is unstable the neutron decays into a proton (beta decay) with the

emission of an electron and of a neutrino. The neutron capture equation is


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4. What is uranium enrichment?

Uranium is a naturally-occurring radioactive element, with atomic number 92. Uranium is

commonly found in very small amounts in rocks, soil, water, plants, and animals (including

humans). Uranium is weakly radioactive and contributes to low levels of natural background

radiation in the environment. Using uranium as a fuel in the types of nuclear reactors common in

the United States requires that the uranium be enriched so that the percentage of the uranium-235

isotope is increased, typically to 3 to 5%. Uranium enrichment is an isotopic separation process

that increases the proportion of the uranium-235 isotope in relation to uranium-238 in natural

uranium. The fuel for nuclear reactors has to have a higher concentration of Uranium-235 than

exists in nature uranium one. This is because Uranium-235 is fissionable, meaning that in

Uranium-235 is required in commercial light-water reactors to centrifuge and laser separation are

used to enrich the uranium.

5. Production of energy from the chain reaction is large and continuous. How can it be

controlled and utilized?

Since the continued chain reaction of a nuclear fission reactor depends upon at least one neutron

from each fission being absorbed by another fissionable nucleus, the reaction can be controlled by

using control rods of material which absorbs neutron. Cadmium and boron are strong neutron

absorbers and are the common materials used in control rods. The control used in TRIGA Reactor


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Puspati is boron carbide. In the operation of a nuclear reactor, the fuel is put into place and then the

control rods are slowly lifted until the chain reaction just be sustained. The control rods are put

down to absorb the excess neutrons if the reaction is needed to be stop.

6. List example of isotopes used in medical physics. Show the nuclear reaction equations

involving the isotopes.

a. Iodine is used to treat cuts and scrapes on the skin as a tincture of iodine, which is a dilute

mixture of alcohol and iodine. Iodine is also used in photography and lasers (silver iodide),

in dyes, and as a nutrient added to table salt. Iodine-131 is used for a number of medical

procedures, including to monitor and trace the flow of thyroxin from the thyroid. With its

short half-life of 8 days, it is essentially gone in less than three months. Iodine-129 has no

important commercial uses.

b. Technetium is a very good corrosion inhibitor for steel, and protection can be achieved by

adding only very small amounts during production. However, this use is limited by the

Technetium radioactive nature of technetium. Technetium-99m is commonly used in

nuclear medicine as a radioactive tracer. In this application, the radionuclide is chemically

attached to a drug chosen for its tendency to collect in specific organs of the body, and the

solution is then injected into the patient. After a short time (its half-life is only 6 hours), an

image is collected with a radiosensitive detector for analysis. This technique is very useful

in identifying cancer metastases in locations distant from primary tumors.


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c. Cobalt is used as a component of several alloys, including carboloy and stellite that are

used to make very hard cutting tools. Cobalt is also used in some stainless steels. Alnico,

an alloy of aluminum, nickel, cobalt, and other metals, is used to make high-strength,

permanent magnets. Cobalt is also used in electroplating to give a hard surface that is

resistant to oxidation, and as a blue colorant in pottery enamels and glass. High-energy

gamma rays emitted during the radioactive decay of cobalt-60 can be used to detect flaws

in metal components and in brachytherapy to treat various types of cancer. (Brachytherapy

is a method of radiation treatment in which sealed sources are used to deliver a radiation

dose at a distance of up to a few centimeters by surface, intracavitary, or interstitial

application.)


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7. List of uses of gamma rays in the plant SINAGAMA. Why not alpha or beta rays?

In the plant SINAGAMA, they use gamma rays for sterilization for medical product,

Radiation Vulcanized Natural Rubber Latex, a microbial-product based company has sent

vermiculite medium and product containers for gamma irradiation, treatment of drinking

water, wastewater and industrial effluents and also in food irradiation. Gamma rays are

preferred because Gamma rays do not lose energy continuously, as do alpha and beta

particles, when passing through an absorber. As a result gamma rays are much more

penetrating than alpha or beta particles. Gamma radiation is attenuated exponentially when

it passes through a shielding material. Therefore, theoretically, gamma rays are never

completely absorbed no matter how thick the shield.

Alpha particles lose energy rapidly in any medium because of their relatively high

ionization loss and are stopped by very thin absorbing materials. A few sheets of paper or

thin aluminum foil will absorb alpha particles from alpha-emitting sources. The most

energetic alpha will travel only a few tens of mm in air. The outer layer of skin,

approximately 0.07 kg/m2 in thickness, will absorb alpha particles up to 7.5 MeV. Since

this is a dead layer of tissue, no harmful effect is produced upon the body. Therefore alpha

particles do not present a shielding problem.

Beta particles have a very small mass and one-half the magnitude of the charge of alpha

particles. So for a given energy, beta particles have a much greater velocity than alpha

particles. As a result beta particles have a lower specific energy loss, which means that

their penetration in any absorber will be much greater than that of alpha particles. The


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process by which beta particles lose energy in absorbers are similar to those for alpha

particles. However, an additional problem encountered when shielding against beta

radiation is the process whereby electromagnetic radiation(secondary X-rays), called

bremsstrahlung, are produced.

8. How electron beam can be produced?

Cathode rays also called an electron beam or e-beam are streams of electrons observed in

vacuum tubes, i.e. evacuated glass tubes that are equipped with at least two metal

electrodes to which a voltage is applied, a cathode or negative electrode and an anode or

positive electrode. Cathode rays are so named because they are emitted by the negative

electrode, or cathode, in a vacuum tube. To release electrons into the tube, they first must

be detached from the atoms of the cathode. In the early cold cathode vacuum tubes, called

Crookes tubes, this was done by using a high electrical potential between the anode and the

cathode to ionize the residual gas in the tube; the ions were accelerated by the electric field

and released electrons when they collided with the cathode. Modern vacuum tubes use

thermionic emission, in which the cathode is made of a thin wire filament which is heated

by a separate electric current passing through it. The increased random heat motion of the

filament atoms knocks electrons out of the atoms at the surface of the filament, into the

evacuated space of the tube. Electron beam, stream of electrons as from a beta generated by

heat called thermionic emission, bombardment of charged atoms or particles as secondary

electron emission, or strong electric fields called field emission. Electrons may be

collimated by holes and slits, and, because they are electrically charged, they may be

deflected, focused, and energized by electric and magnetic fields. Electron beams are used


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chiefly in research, technology, and medical therapy to produce X rays and images on

television screens, oscilloscopes, and electron microscopes. Since the electrons have a

negative charge, they are repelled by the cathode and attracted to the anode. They travel in

straight lines through the empty tube. The voltage applied between the electrodes

accelerates these low mass particles to high velocities. Cathode rays are invisible, but their

presence was first detected in early vacuum tubes when they struck the glass wall of the

tube, exciting the atoms of the glass and causing them to emit light, a glow called

fluorescence. Researchers noticed that objects placed in the tube in front of the cathode

could cast a shadow on the glowing wall, and realized that something must be travelling in

straight lines from the cathode. After the electrons reach the anode, they travel through the

anode wire to the power supply and back to the cathode, so cathode rays carry electric

current through the tube.

9. What are the characteristics of the electron beam used in the manufacturing sector,

medical, industrial, etc?

The electron beam used in the manufacturing sector, medical, industrial has energy about

2.0 MeV to 10 MeV energy. The power of electron beam is about 1.5 kW/unit to

400kW/unit. The dose rate of it is high, that is about 10kGy/second. Besides that, the

penetration of the electron beam is low, which mean it only can penetrate about

0.35cm/MeV. Therefore, it is suitable for the irradiation of this material such as plastics

films and surface coatings. Moreover, the energy utilization efficiency of electron beam is

between 10% to 90%. The electron beam has high production rate.


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10. What career in the field of radiation and nuclear physics? How to get there?

There are a lot of profession in radiation and nuclear physics field today. For examples are

medical health physicist, nuclear engineers, nuclear physicist, nuclear pharmacist, nuclear

power reactor operators, nucleation weapons health physicist and others. For who want to

focus in this career, he should have the required education level in the related field such as

degree and other higher level of education in engineering, nuclear specialty and science,

medical, physics, radiation, machines, electric and so on in Malaysia, the career in this field

is also widely found especially in field of medical and nuclear and radiation research. For

those career in the government institutions like Malaysia Nuclear Agency, ones can take

the related degree and later fill up the SPA8i form and send to the related institution

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