Pressurized Water Reactor

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1. P ressurized Water R eactor Presented by: MUHAMMAD KASHIF SAEED UZ ZAMAN SIDDEQI ZAIN UL ABIDEEN MUHAMMAD FAROOQ MUHAMMAD JAVED KHAN BASHIR AHMAD Presented to : MAAM ROOBI ZAHRA UW-17-CE-BSC-021 UW-17-CE-BSC-047 UW-17-CE-BSC-050 UW-17-CE-BSC-042 UW-17-CE-BSC-029 UW-17-CE-BSC-028

2. P ressurized Water R eactor A nuclear reactor in which the fuel is uranium oxide clad in zircaloy and the coolant and moderator is water at high pressure so that it does not boil at the operating temperature of the reactor.

3. W orking P ressurized W ater N uclear R eactor The core inside the  reactor  vessel creates heat.  Pressurized water  in the primary coolant loop carries the heat to the steam generator. The steam line directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity.

4. P urpose of the Pressurizer in a Nuclear R eactor A  Pressurizer  is a component of a pressurized water reactor . To pressurize the coolant system to a higher pressure than the boiling point of the coolant at operating temperatures, a separate pressurizing system is required. That is the  function of the pressurizer .

5. Production of E lectricity Nuclear plants, like plants that burn coal, oil and natural gas,  produce electricity  by boiling  water  into steam. ... Nuclear power plants obtain the heat needed to produce  steam through a physical process. This process, called fission, entails the splitting of atoms of uranium in a nuclear  reactor .

6. PWR Reactor D esign Coolant Light water  is used as the primary coolant in a PWR . Water enters through the bottom of the reactor's core and is heated as it flows upwards through the reactor core to a temperature of about 588 K . The water remains liquid despite the high temperature due to the high pressure in the primary coolant loop, usually around 155  bar   . In water, the  critical point  occurs at around 647 K and 22.064  M Pa .

7. Pressurizer To achieve a pressure of 155 bars the pressurizer temperature is maintained at 345 °C , which gives a sub cooling margin of 30 °C . As 345 °C is the boiling point of water at 155 bar, the liquid water is at the edge of a phase change.

8. Pumps The coolant is pumped around the primary circuit by powerful pumps .  After picking up heat as it passes through the reactor core, the primary coolant transfers heat in a steam generator to water in a lower pressure secondary circuit, evaporating the secondary coolant to saturated steam — in most designs 6.2  M Pa , 275 ° C— for use in the steam turbine. The cooled primary coolant is then returned to the reactor vessel to be heated again.

9. Moderator A  moderator  is a material used in a  nuclear reactor  to slow down the  neutrons produced from fission. By slowing the  neutrons  down the probability of a  neutron interacting with Uranium-235 nuclei is greatly increased thereby maintaining the chain reaction.

10. Fuel After enrichment, the  Uranium Dioxide  ( UO2 ) powder is fired in a high-temperature .   S intering  furnace to create hard ceramic pellets of enriched uranium dioxide . The cylindrical pellets are then clad in a corrosion-resistant zirconium metal alloy  Zircaloy  which are backfilled with helium to aid heat conduction and detect leakages.

11. Control  The reactor control rods, inserted through the reactor vessel head directly into the fuel bundles, are moved for the following reasons: To start up the reactor. To shut down the primary nuclear reactions in the reactor. To accommodate short term transients, such as changes to load on the turbine. The control rods can also be used: To compensate for  nuclear poison  inventory. To compensate for  nuclear fuel  depletion.

12. Advantages PWR reactors are very stable due to their tendency to produce less power as temperatures increase; this makes the reactor easier to operate from a stability standpoint. PWR turbine cycle loop is separate from the primary loop, so the water in the secondary loop is not contaminated by radioactive materials. PWR technology is favoured by nations seeking to develop a nuclear navy; the compact reactors fit well in nuclear submarines and other nuclear ships.

13. Disadvantages Additional high pressure components are also needed. This also increases the capital cost and complexity of a PWR power plant . The requirement to enrich fuel for PWRs also presents a serious  proliferation  risk. Because water acts as a neutron moderator, it is not possible to build a  fast neutron reactor  with a PWR design .