In-vessel transfer machine

Considerable progress has been made in the design of component handling systems. For handling core subassemblies within the main vessel, transfer arm type In-vessel Transfer Machine (IVTM) has been selected. For transporting core subassemblies towards the external storage,... 

In-vessel transfer machine (IVTM). This transfer machine is located in the reactor vessel during refueling operations and moves (1) fresh fuel and other core components from CCPs near the outside edge of the reactor vessel to positions in the reactor core and (2) SNF and other used core components from the core to the CCPs. 

Two IHXs and four EM primary pumps are suspended in the reactor vessel by the reactor closure. Primary control rod drives, ultimate shutdown rod drives, in-vessel instrumentation, and an in-vessel transfer machine (IVTM) for fuel handling are suspended from the rotatable plug in the closure [3]. The reactor closure with major equipment is shown in Figure 6.9. 

Spent fuel handling. Spent fuel is taken from the core and transferred to a tank in the lower part of an in-vessel transfer machine. This is done by a fuel handling machine of the pantograph fixed-arm type. After the fuel has been removed from the reactor vessel with an exvessel transfer machine, it is transferred through a containment equipment hatch. Later it is stored in a fuel cooling pond after sodium cleaning. 

The design of upper internal structure (UIS) and variable arm type in-vessel transfer machine (IVTM). Required are ... 

In-vessel handling is carried out using two rotatable plugs and an offset (fixed) arm type fuel handling machine (IVTM). An ultrasonic scanner is provided in order to check projection of any SA/absorber rods above the top of the core before starting in-vessel transfer operation. Additionally, strict administrative control on interlocks is to be provided. An Inclined fuel transfer machine (IFTM) is used to transfer the subassemblies from the main vessel to outside. 

An overall plan view of the FFTF reactor refueling facilities is shown in Fig. 5.2. The principal exreactor component is the closed loop ex-vessel machine (CLEM), shown in Fig. 5.3. The CLEM loads all components into the reactor vessel and removes all components from the reactor core. Fresh driver fuel and all SNF is transferred to and from the reactor in a core component pot (CCP) that can be inserted or removed through one of three fuel transfer ports in the reactor vessel top cover. The in-reactor components consist of three in-vessel handling machines (IVHMs) plus the three in-vessel storage modules. The FFTF requires three IVHMs because of closed test loops in the reactor core which interfere with direct access to the entire reactor core with one machine. 

After the reactor is shut down, the ex-vessel transfer machine (EVTM) transfers a new fuel assembly, in a sodium-filled CCP, from the EVST to the reactor through a 44.5 hatch in the reactor containment building (RCB) wall. When the new fuel assembly arrives at the reactor, it is discharged from the EVTM into a transfer position on the periphery of the reactor core in the reactor vessel. 

Reactor refueling systems. A series of systems associated with the reactor and reactor vessel are required for refueling. Outside the reactor vessel these include three fuel transfer ports, eight test position spool pieces, two floor valve ad ters and the test transfer port, and the reactor containment building cranes. Inside the reactor vessel are three in-vessel handling machines (IVHMs) and three invessel storage modules. Three IVHMs are required because of the mission of the FFTF that requires closed test loops in the reactor core which interfere with direct access to die entire core with one machine. 

Ex-vessel transfer machine (EVTM). This rail-mounted transfer cask moves core component pots (CCPs) with fresh fuel and other core components from the EVST to the reactor vessel and moves CCPs with SNF and other core components from the reactor vessel to the EVST. The CCPs are small vessels used to transfer fuel and other components in a temperature-controlled sodium environment. The EVTM is also used for fresh fuel, SNF, and other transfer operations within the reactor service building and remains in the reactor service building during reactor operations. 

Where pipe-lines are used to transfer bulk materials to remote holding vessels or filling machines it must be ensured that the material is, in fact, delivered to the intended vessel or machine. 

The core components are spent fuel assembly (SA), irradiated blanket SA and irradiated absorber SA. There are 94 core SA to be cleaned from sodium in eight months full power reactor operation. The core SA coming out of the reactor is handled by cell transfer machine. This machine picks up the core SA from the ex-vessel transfer position and keeps it in the washing vessel. The flow sheet of the SA washing is shown in Fig. 3. 

Fig. 4.3. Schematic of Fort St. Vrain refueling machine. Shown are in-vessel robotic arm over the reactor core relationship of refueling machine, reactor vessel top, and reactor core and refueling machine placing fuel element in transfer cask.

Tests on in-service inspection machines for the reactor vessel and enclosure, the primary main cooling piping and heat transfer tubes in the steam generator, were also carried out. 

Mechanical Design. Typically, each battery will have a thermal sleeve around each cell. The cells are mechanicily restrained by clamping them in a precision-machined sleeve. These sleeves can be made of either a metal such as aluminum or a composite made in a manner to provide electrical isolation, high thermal conductivity and strength. The sleeve is isolated electrically from the cell by a blanket, such as CHO-THERM which allows thermal transfer, wrapped around the cylindrical portion of the cell between the cell and sleeve. The space between the sleeves, blanket and cell is normally filled with a material such as an RTV 566 to provide better thermal transfer as well as to bond the interfaces mechanically. The sleeves are then either attached mechanically to a base plate which is the interface to the satellite structure or are attached to an interface such as extruded heat pipe assemblies which are a part of the satellite structure. The exposed surfaces of the cells are protected by a coating of Solithane or a combination of paint on the cell pressure vessel and Solithane. The desired battery voltage defines the number of cells used for the assembly. 

---