10. In most commercial thermal reactors the fuel is either uranium (0.7% uranium-235 ),w ith heavy water or graphite as the moderator, or uranium containing 2-4 percent of the fis with ordinary water as the moderator.>> l1. Based on the purpose, the reactor can fall into experimental (or research)reactor, pro uction reactor, power reactor, dual purpose (power and production) reactor or nuclear heati 12. According to the type of coolant and moderator, reactor can be called pressurized wat r reactor, boiling water reactor, heavy water reactor (e.g. CANDU), graphite reactor, or li quid metal cooled reactor. UNIT 7 INSTRUMENTATION<OV 1. In addition to conventional instrumentation, such as that required fir measuring temperat ures, pressures,coolant flow rates, etc, devices(sensors)for determining the neutron flux play an important role in reactor control and safety. > 2. Many instruments for the detection of nuclear radiation are dependent upon the behavio r in an electrical field of the ion-pairs formed by the ionizing particles in their passage th rou 3. Neutrons are unchanged particles and therefore cannot cause ionization directly, so they must interact with matter by means of a nuclear reactor which, in turn, will generate cha 4. The changed particles will cause ionization within a gas-filled detector and these ion pa irs will produce a voltage pulse or some mean level current when collected at the electro des of the detector.>> 5. Since the neutron flux covers a wide range(12 decades), no single instrument can prov ide a satisfactory indication of the neutron flux and hence three ranges, i.e., source range intermediate range and power range, of instrumentation are used to obtain accurate flux I evel measures. >> 6. BF3 gas generated filled detectors (proportional counter) are used in source range, com pensated ion chamber are in the intermediate range, and uncompensated ion chamber in th e power range in some nuclear power plant.>> 7. Since gamma radiation from fission and fission products in a reactor can be very inten se, the compensated ionization chambers are required in the intermediate range 8. The fission chamber is coated with a uranium compound and pulse produced by the fis sion fragments resulting from the interaction of neutrons with the uranium-235 are so larg
10. In most commercial thermal reactors the fuel is either uranium (0.7% uranium-235), w ith heavy water or graphite as the moderator, or uranium containing 2-4 percent of the fis sile isotope, with ordinary water as the moderator.>> 11. Based on the purpose, the reactor can fall into experimental (or research) reactor, prod uction reactor, power reactor, dual purpose (power and production) reactor or nuclear heati ng reactor.>> 12. According to the type of coolant and moderator, reactor can be called pressurized wat er reactor, boiling water reactor, heavy water reactor (e.g. CANDU), graphite reactor, or li quid metal cooled reactor. UNIT 7 INSTRUMENTATION<O 1. In addition to conventional instrumentation, such as that required fir measuring temperat ures, pressures, coolant flow rates, etc., devices (sensors) for determining the neutron flux play an important role in reactor control and safety.>> 2. Many instruments for the detection of nuclear radiation are dependent upon the behavio r in an electrical field of the ion-pairs formed by the ionizing particles in their passage th rough a gas.>> 3. Neutrons are unchanged particles and therefore cannot cause ionization directly, so they must interact with matter by means of a nuclear reactor which, in turn, will generate cha rged particles.>> 4. The changed particles will cause ionization within a gas-filled detector and these ion pa irs will produce a voltage pulse or some mean level current when collected at the electro des of the detector.>> 5. Since the neutron flux covers a wide range (12 decades), no single instrument can prov ide a satisfactory indication of the neutron flux and hence three ranges, i.e., source range, intermediate range and power range, of instrumentation are used to obtain accurate flux l evel measures.>> 6. BF3 gas generated filled detectors (proportional counter) are used in source range, com pensated ion chamber are in the intermediate range, and uncompensated ion chamber in th e power range in some nuclear power plant.>> 7. Since gamma radiation from fission and fission products in a reactor can be very inten se, the compensated ionization chambers are required in the intermediate range. 8. The fission chamber is coated with a uranium compound and pulse produced by the fis sion fragments resulting from the interaction of neutrons with the uranium-235 are so larg
e that there is no difficulty in discriminating even against"pile-up''pluses from gamma ra 9. Pressure, defined as force per unit area, is one of the measured and controlled properti 10. Typically application of Borden tube pressure sensors is locally mounted pump suction and discharge pressure gages. >> 11. Thermocouples are utilized as temperature sensors t core exits.>> 12. The hot and gold leg temperature detectors of Reactors Coolant System are Resistance Temperature Detectors(RTDs) unit 8 ENERGY REMOVAL 1. In practical, the maximum power level of a reactor is normally determined by the rate at which the energy(heat) can be removed.>> 2. In nuclear reactor operating at high neutron flux, such as those intended for central stat ion power or ship propulsion, the design of the core depends just as much on the heat re moval aspects as on nuclear consideration.>> 3. The term thermal-hydraulic design is commonly used to describe the effort involving th e integration of heat transfer and fluid mechanics principles to accomplish the desired rate of heat removal from the reactor fuel.>> 4. The temperature in a reactor could increase continuously until the reactor is destroyed i f the rate of heat removal were less than the rate of heat generation.>> 5. The rate of heat generation and heat removal must be proper balanced in a operating r 6. The maximum of permissible temperature must be definitely established to make sure t hat the cooling system is adequate under anticipated operating conditions.>> The temperature at any point in a reactor will be greater than that of the sink by amo unt equal to the sum of all the temperature drops along the heat-flow path.>> 8. The goal of reactor thermal-hydraulic design is to provide for the " optimum"transport of heat from the fuel to its conversion into useful energy, normally in a turbine. > 9. By"optimum"is meant a proper balance between many opposing parameters, such as coolant flow rate, temperature distribution in the core, materials, etc. >>
e that there is no difficulty in discriminating even against “pile-up” pluses from gamma ra ys.>> 9. Pressure, defined as force per unit area, is one of the measured and controlled properti es.>> 10. Typically application of Borden tube pressure sensors is locally mounted pump suction and discharge pressure gages.>> 11. Thermocouples are utilized as temperature sensors t core exits.>> 12.The hot and gold leg temperature detectors of Reactors Coolant System are Resistance Temperature Detectors (RTDs). UNIT 8 ENERGY REMOVAL 1. In practical, the maximum power level of a reactor is normally determined by the rate at which the energy (heat) can be removed.>> 2. In nuclear reactor operating at high neutron flux, such as those intended for central stat ion power or ship propulsion, the design of the core depends just as much on the heat re moval aspects as on nuclear consideration.>> 3. The term thermal-hydraulic design is commonly used to describe the effort involving th e integration of heat transfer and fluid mechanics principles to accomplish the desired rate of heat removal from the reactor fuel.>> 4. The temperature in a reactor could increase continuously until the reactor is destroyed i f the rate of heat removal were less than the rate of heat generation.>> 5. The rate of heat generation and heat removal must be proper balanced in a operating r eactor.>> 6. The maximum of permissible temperature must be definitely established to make sure t hat the cooling system is adequate under anticipated operating conditions.>> 7. The temperature at any point in a reactor will be greater than that of the sink by amo unt equal to the sum of all the temperature drops along the heat-flow path.>> 8. The goal of reactor thermal-hydraulic design is to provide for the “optimum” transport of heat from the fuel to its conversion into useful energy, normally in a turbine.>> 9. By “optimum” is meant a proper balance between many opposing parameters, such as coolant flow rate, temperature distribution in the core, materials, etc.>>
10. An important aspect of the thermal-hydraulic design is concerned with conditions that might arise from an accident. >> 11. Provision must be made in the design to accommodate deviations from normal operati ng conditions, such as following partial or complete loss in the coolant flow.> 12. Three general mechanisms are distinguished whereby heat is transferred from one point to another, namely, conduction, convection and radiation UNIT 9 REACTOR MATERIALS 1. A unique aspect of reactor environment is the presence of intense nuclear radiations of vari Ous 0 2. Mechanical properties, such as tensile strength, ductility, impart strength and creep, must be adequate for the operation conditions. <OV></OVh 3. The material must be able of being fabricated or joined, e.g., by welding, into the required 4. An important requirement for structural and cladding materia ls is that they have a smal ads orption cross section for neutrons. <oOx/08 5. The alloys in common use as cladding material are zircaloy-2 and zircaloy-4, both of which have good mechanical properties and corrosion resistance. oOx/oe 6. Ordnary water is attractive as a moderator because of its low cost, its excellent slowing wn power. <ov></ov
10. An important aspect of the thermal-hydraulic design is concerned with conditions that might arise from an accident.>> 11. Provision must be made in the design to accommodate deviations from normal operati ng conditions, such as following partial or complete loss in the coolant flow.>> 12.Three general mechanisms are distinguished whereby heat is transferred from one point to another, namely, conduction, convection and radiation. UNIT 9 REACTOR MATERIALS 1. A unique a spect of reactor environment is the presence of intense nuclear radiations of vari ous types.<O ></O > 2. Mechanical properties, such as tensile strength, ductility, impart strength and creep, must be adequate for the operation conditions.<O ></O > 3. The material must be able of being fabricated or joined, e.g., by welding, into the required shape.<O ></O > 4. An important requirement for structural and cladding materials is that th ey have a small ads orption cross section for neutrons.<O ></O > 5. The alloys in common use as cladding material are zircaloy-2 and zircaloy-4, both of which have good mechanical properties and corrosion resistance.<O ></O > 6. Ordinary water is attractive as a moderator because of its low cost, its excellent slowing-do wn power.<O ></O >