Term
| State the purpose and function of nuclear fuel. |
|
Definition
| Provide energy to produce heat for steam generation. |
|
|
Term
| State the number of fuel bundles in the core. |
|
Definition
|
|
Term
| State the definition of a control cell. |
|
Definition
| a control rod and the four fuel assemblies immediately surrounding it. |
|
|
Term
| Function and location of Fuel Channel |
|
Definition
| Function: Separates parallel flowpaths; provides rigidity and protects bundle from damage during transit; Guide/bearing surface for CRD blade. |
|
|
Term
| Function and location of Cladding |
|
Definition
| Contains fission products; transfers heat from fuel pellets to coolant. |
|
|
Term
| Function and location of Nose Piece |
|
Definition
| Vertical support for assemblies. Also directs coolant up through bundle. First bypass flowpath. |
|
|
Term
| Function and location of Lower Tie Plate |
|
Definition
| Stainless steel plate located at the base. Used to tie the bundle together. Nose piece directs coolant up through bundle. Holes drilled in 2 sides of Lower Tie Plate for bypass flow to cool in-core instruments. Second bypass flowpath. |
|
|
Term
| Function and location of Expansion Spring |
|
Definition
| Supplies compression loading of fuel rods. |
|
|
Term
| Function and location of Finger Springs |
|
Definition
| held in place via mating of fuel rod - lower end plugs into lower tie plate. Restricts the flow of coolant from the bundle into the area outside the channel. Third bypass flowpath. |
|
|
Term
| Function and location of Fuel Pellet |
|
Definition
| "High density UO2 (Uranium Dioxide) sintered. Retains fission gases, except from surface reactions. The pellet is the first barrier to the release of fission products to the environment. Chamfered edges. Stacked in fuel rod." |
|
|
Term
| Function and location of Interim Fuel Spacer |
|
Definition
| GE14: 8 at non-uniform intervals to lower the 2-phase pressure drop and maximize critical power performance. |
|
|
Term
| Function and location of Water Rod |
|
Definition
| Hollow with holes. Number varies according to fuel type. Serves to flatten flux across bundle. |
|
|
Term
| Function and location of Fuel Rod |
|
Definition
| Contains fission products; transfers heat from fuel pellets to coolant. 10x10 pin fuel rods make up fuel assembly. |
|
|
Term
| Discuss the 5 methods available to verify correct fuel bundle orientation. |
|
Definition
In each control cell, channel fastener assemblies adjacent in center of cell; Identification bosses on bundle handles point towards center of cell; Channel spacer buttons adjacent to each other; Bundle serial numbers on handles readable from center of cell; Cell-to-cell symmetry."
|
|
|
Term
| Predict at least one consequence of improper orientation. |
|
Definition
| "Improper orientation can lead to high peaking factors, localized fuel burnup and possibly fuel damage. " |
|
|
Term
| Define zirc hydriding - state the conditions necessary to promote zirc hydriding. |
|
Definition
| "Free Hydrogen combines chemically with zirconium to form zirconium hydride. The hydrogen comes from water and fuel rod contaminants during manufacturing (moisture in pellets, clad identification and fuel rod "atmosphere"). Hydriding will continue as long as hydrogen is available." |
|
|
Term
| Discuss one advantage of using pre-pressurized fuel. |
|
Definition
| Promotes heat transfer (thermal convection) in new fuel (therefore lower centerline temperature). |
|
|
Term
| Discuss the mechanism of Pellet Cladding Interaction (PCI) and actions taken to prevent it. |
|
Definition
result of excessive localized cladding strain. Fuel pellet expands as pellet power and age increase. Pellet expands at rate greater than clad. Pellet contacts clad and causes deformation. Clad under extreme stress deforms plastically. If sufficient deformation occurs, then clad cracks. Clad also becomes more brittle over life;
ACTIONS to control: pellet chamfering; PCIOMR (Pre-Conditioning Interim Operating Management Recommendations (Regime of clad preconditioning and slow controlled power ramps); For ""Barrier Fuel"", inner surface of clad has soft metal overlay to absorb stresses due to pellet growth. Barrier fuel reduces problems associated with pellet-clad interaction."
|
|
|
Term
| State the purpose of burnable poisons and why they are utilized. |
|
Definition
"A material, which absorbs neutrons more readily than fuel but does not produce fission as a result. |
|
|
Term
| "Per Tech Spec Section 2.0, under what conditions shall the MCPR limit be greater than or equal to 1.10?" |
|
Definition
| Steam Dome pressure greater than or equal to 785 psig and core flow greater than or equal to 10% for two loop operation |
|
|
Term
| "Per Tech Spec Section 2.0, under what conditions shall the MCPR limit be greater than or equal to 1.12?" |
|
Definition
| Steam Dome pressure greater than or equal to 785 psig and core flow greater than or equal to 10% for single loop operation |
|
|
Term
| "Per Tech Spec section 2.0, under what conditions shall core thermal power not exceed 25%?" |
|
Definition
| Steam dome pressure less than 785 psig or core flow less than 10% rated core flow. |
|
|
