UEET 603 Introduction to Energy Engineering Spring 2010

1. UEET 603 Introduction to Energy Engineering Spring 2010 Nuclear Power

2. Nuclear Energy Nuclear energy is a way of creating heat through the fission process of atoms. Nuclear energy originates in and emanates from the fission of atomic nucleus in a chain reaction. Nuclear fission reaction is control in a nuclear rector to produce thermal energy.

3. The fission process takes place when the nucleus of a heavy atom like uranium or plutonium is split when struck by a neutron. The fissioning of the nucleus releases two or more new neutrons. It also releases energy in the form of heat. The released neutrons can then continue to split additional nucleus . - This releases even more neutrons and more nuclear energy. - The repeating of the process leads to a chain reaction.

4. Current Use of Nuclear Power All nuclear power plants convert heat into electricity using steam. The heat is created when atoms are split apart – call fission. The heat from fission reaction is used to produce steam, which is then used to turn a turbine and produce electricity using a generator. Power from nuclear fission accounts for about 19% of the nation’s total energy. Number operating nuclear power plants is 120 ?? Mostly safe, successful and well regulated No new plant has been built in last 30 years

5. Current use of Nuclear power Generation of power or electricity in stationary applications like in a nuclear power plants, propulsion of mobile system like naval vessels, especially submarines as well as several surface vessels. Since nuclear plants do not consume oxygen like conventional plants, it is quite attractive for use under sea. Also, ships powered by nuclear plants need to be refueled only after long periods of operation. Nuclear power has also been developed for the propulsion of aircraft and rockets.

6. Major concern and Obstacles Safe operation of the plant and safe handling and disposal of nuclear fuels Concern of environmentalists about the dangers of storing the radioactive byproducts of the process Cost of building a new nuclear reactor is about $10 billion each – One of the main reason for a stagnant industry. Reduction cost of other fuel like coal, natural gas and oil, make the nuclear power production less competitive. Each project has to pass through a rigorous scrutiny and check through Nuclear Regulatory Commission (NRC) before construction can begin.

7. Needs economic guarantee from the government to it seems difficult for the utility companies to start any new projects. Government recently committed $8.33 billion in loan guarantees for the construction of two new reactors at the Alvin W. Vogtle Electric Generating Plant in Georgia - Expected to which provide electricity to over a million people by next 5-6 years.

8. Atomic and Nuclear Physics Fundamental Particles The physical world is composed of various subatomic or fundamental particles. There are variety of different fundamental particle ,and scientist are still finding newer ones . However , only few of these are important in nuclear engineering: - Electrons - Proton - Neutron - Photon - Neutrino

9. Fundamental Particles Electrons: This particle has rest massof and carries a charge Mass of a particle is a function of its speed relative to the observer In giving the mass of fundamental particle, it is necessary to specify the mass at rest with respect to the observer - termed as rest mass.

10. There are two types of electrons: Negatrons or negative electrons: Carries a negative charge Normal electrons encountered in this world. Positrons or positive electrons: carries a positive charge Relatively rare in this world These two are identical except the sign of the charge

11. Electron Annihilation Process   When under circumstances, a positron collide with a negatron, the electrons disappear and two (occasionally more) photon (particles of electromagnetic radiation) are emitted. Proton   This particle has a rest mass of and carries a positive charge equal in magnitude to the charge on the electron. Protons with negative charge have also been discovered, but these particles are of no importance in nuclear engineering.

12. Neutron The mass of neutron is Slightly larger than the mass of the proton. The neutron is not a stable particle, except when it is bound into an atomic nucleus. A free neutron decays to a proton with the emission of a negative electro ( Known as )

13. Photon: Particle equivalent of electromagnetic wave. This is a particle with zero rest mass and zero charge, which travels in a vacuum at only one speed, namely the speed of light Neutrino This also a particle with zero rest mass and no electrical charge. This appears in the decay of certain nuclei. There are two types of Neutrinos: neutrinos and antineutrinos

14. Type of Power Reactor Light -Water Reactor (LWR) - Pressurized-water reactor (PWR) - Boiling water reactor (BWR) Gas Cooled Graphite moderated Reatcor - High temperature gas cooled reactor (HTGR Heavy -Water Reactor (HWR) Breeder Reactor (BR)

15. Light-Water reactor (LWR) Light water is used as a moderator as well as a coolant The water in a PWR is maintained at a high pressure in the range of 2000-2500 psi to prevent water from boiling. There are two types of light-water reactors: - Pressurized-water reactor (PWR) - Boiling-water reactor (BWR)

16. Water has excellent moderating properties as well as thermodynamic properties to produce steam. But has high vapor pressure. LWR has to be operated at high pressure. Water also absorbs neutrons to such an extent that it is not possible to fuel a LWR with natural uranium – it would not become critical. Need enriched uranium fuel. Uranium in water reactors must always be enriched to some extent.

17. High pressure water is circulated through the reactor core to pick up heat without any boiling of water. Pressurize hot water is then circulated through the steam generator where heat is transferred to a secondary water stream that enters as liquid water and exits steam. High pressure and high temperature steam is then turns turbine to produce electric power undergoing a Rankine cycle. Large PWR system uses as many as four steam generator, which produce steam at about 560 F and 900 psi. This gives an overall efficiency of 32-33 % for a PWR plant

18. Boiling Water Reactor (BWR) Water is boiled directly in the reactor vessel and produces steam to turn the turbine. Steam is produced directly inside the reactor and there is no need of a separate steam generator. Steam from the rector goes directly to the turbine to produce power. Referred to as the direct cycle.

19. More effective in removing heat from the fission react to the use of latent heat rather than using the sensible heat. Less water need to be pumped through the reactor than a PWR for the same net power output However the water become radioactive in passing through the reactor core. Since this water is utilized in the electricity producing side of the plant, all of the components of the steam utilizing system: the turbines, condensers, reheaters, pumps, piping must be shielded in a BWR Plant • The pressure in a BWR is approximate 1000 psi, about twice the pressure in a PWR. • As a results the wall of the pressure vessel for a BWR need not be as thick as it is for a PWR. • However the power density (Watt/cm^2) is smaller in a BWR than a PWR, and so overall dimension of a pressure vessel for BWR must be larger than for PWR