Out-in refueling

The flow scheme of the out-in refueling core is described by Fig. 2.66 [9]. Among the 121 fuel assemblies, 89 inner fuel assemblies are cooled by upward flow of the coolant, while the 32 outer fuel assemblies are cooled by coolant downward flow. The core pressure is 25 MPa and the inlet coolant temperature is 280°C. Most of the inlet coolant (76.7%) is guided to the top dome and distributed to the water rods of the inner fuel assemblies (30.0% of the inlet coolant), water rods of the outer fuel assemblies (10.8% of the inlet coolant), and the fuel channels... 

When the outer core downward flow cooling is adopted for the out-in refueling core, the maximum power fuel rod may not belong to the maximum power fuel assembly. As can be seen from the radial core power distributions in Fig. 2.69 [9],... 

In addition to the tetraethyl or tetramethyl lead, both types of antiknock fluids also contained 1,2-dichloroethane and 1,2-dibromoethane (ca. 35% by weight) to react with the lead released on combustion to form lead bromide and lead chloride. These lead halides are volatile at the cylinder combustion temperatures of 800-900°C, and leave the combustion chamber with the exhaust, which prevented the buildup of lead deposits. This was also the final step in the chain of events occurring with the alkylated lead antiknock compounds, which contributed to the widespread dispersal of lead compounds to the air and soil wherever gasoline powered vehicles operated. For this reason, and the toxic exposures during refueling, the alkylated lead addition rate was reduced to not more than 0.5 g of contained lead per U.S. gallon by 1980, even for leaded gasolines [29], and was phased out in the U.S. and Canada by 1985. 

The number of fuel bundle per each fuel channel is the same, but they are surely less than 12 bundles as used in CANDU and they are not subject to daily refuelling methods. Fuel managem t patterns will be defined through bum up calculation. One third of the fuel channel will be unloaded and loaded at the end of a cycle and due to the fuel management patt defined before, out-in shuffling is undertaken. The fuel bundles in the fuel channel will look like as follows ... 

During reftielling operations the containment dome and the reactor vessel head are removed, and the cavity above the dome is filled with water. The reactor internals are lifted out in sections, and placed in the water-filled cavity. The refuelling is carried out with a conventional refuelling machine from the reactor service room. Fresh fuel is brought into the cavity from a fresh fuel storage in the reactor building, and the spent fuel is removed to an adjacent spent fuel pool at the reactor service room floor level. 

Pressure-retaining components, including the out-of-core channel extensions and the mechanical closures accessed by fueling machines in refueling the channels... 

The problems associated with carrying out the refuelling operation require a high Integrity control system for their solution. The two key criteria for such a control system are (a) safety and (b) system availability. The safety aspects cover areas such as prevention of radioactive release and plant damage whereas system availability Includes reduction of downtime and hence reduction In lost revenue due to the refuelling shutdown. 

Since refuelling can only be carried out in a depressurized state it is very expensive. Can the reactor be operated with failed fuel in the same way as an AGR may be How much refuelling would be done if a pin failed Could not failed... 

As for the fuel loading pattern, the low leakage loading pattern (LLLP) as shown in Fig. 2.73 [21] with the in-out refueling scheme of Fig. 2.74 [22] can be adopted with the outer core downward flow cooUng. When these design options are chosen, the neutron economy becomes better compared with the out-in loading patterns... 

All drivers are responsible for refueling their vehicles at the end of each shift. All other routine maintenance should be performed by maintenance-department personnel, who are also responsible for maintaining service records. If a driver believes a vehicle is in need of mechanical repair, the driver should fill out the pink repair requisition form and give it to the shift supervisor. The driver should also notify the shift supervisor verbally whether, in the driver s opinion, the vehicle must be repaired immediately or may be driven until the end of the shift. 

Fig. 1.1 A novel vision of refueling/retail station for fuel ceU-powered vehicles based on the concept of the off-board recharging of spent hydride fuel and the mechanochemical synthesis of nanostructured hydrogen storage materials in baU-miU plants. Such is not the currently accepted vision of hydrogen economy but one which may turn out to be viable alternative to onboard...

Airplane parts, and even whole airplanes, are now being fabricated out of lightweight advanced composites in order to save fuel. In 1986, the all-composite Voyager, shown in Figure 18.36, was the first plane to fly around the world without refueling. Many private jets are now fabricated out of composites. The general public may one day have its chance to fly in fuel-efficient, stress-resistant composite airplanes. In the meantime, we fly in passenger airplanes made of metal, which are still more economical to build. 

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