Patent Number: 
Section: description

Referring now to the drawings, it will be seen that the automated reactor pellet-loading machine (10) operates as follows. A hopper (12) is loaded with bulk nuclear reactor pellets. Since BP and APSR pellets cause no critically (critical mass) problems the hopper (12) may be manually loaded to the top. However, if fuel pellets are to be used, a 4-inch height must be observed. Thus a hopper pellet height detector (14) preset for this height is utilized. When this height is reached the detector activates an alarm warning of any further full pellet addition. The hopper (12) feeds a rotating pellet bowl (16) by a vibrating pan (18) which is operated by a start signal along line (20) to drop pellets into the rotating bowl (16) until it is shut off by a signal along line (22) from an optical switch (21). The rotating bowl (16) feeds individual spaced pellets unto a conveyor belt (26) which is mechanically connected to a set of pinch rollers (28) which pass single pellets unto an indexed pellet-loading tray (30). The pellets are counted as they enter the tray (30) by the optical counter (24). The tray (30) is shown in FIG. 2 in its initial loading position and has a plurality of corrugated rows (32) each holding approximately 20 to 21 pellets. The tray (30) is indexed to move down one row when the counter (24) reaches the correct count. The movement is sequentially done by a linear positioner (23). The counter is reset to zero and starts the next row (32) count. The counter (24) also has a cumulative counter that totals the pellets.loaded into all the rows (32) of the tray (30) until the number needed to fill a reactor rod is reached. The counter (24) now sends signal along line (25) to the pinch rollers (28) to turn off any further pellet flow from the conveyor belt (26). The tray (30) is now in the xe2x80x9cloading tray run outxe2x80x9d area (34). This same signal along line (25) is passed to the linear positioner to initiate the movement of the filled tray (30) back to its original position shown in FIG. 2 and the sliding of the pellets by the rake (36) portion into the pellet que and weighting tray (38) which is identical to the tray (30) except that it is located over a weighting device.(not shown). For BP and APSR pellets, the weighting is unnecessary and the entire tray (30) can be moved to the tray (38). As was mentioned earlier, for fuel pellets the w eight is an indication of reactivity and the pellet transfer will occur only when the desired weight or reactivity is confirmed. Thus, for fuel pellets the desired weight is inputted as a set point to a known comparator which compasses it with the predetermined set point weight to establish a control signal along line (40) to the linear positioner (36) indicating a completing of the pellet transfer to the tray (32). For BR and APSR pellets the end of the rake travel along tray (32) will establish a control signal along line (42) to the linear positioner (36) indicating same. The linear positioner then moves to the tray (38) and with the rake (36) moves the pellets to a pellet unloading tray (44) which is identical to the trays (30) and (38). When the rake (36) reaches the end of the tray (38), a control signal is established along line (46) for the linear positioner to move to tray unloading tray (44). Here the positioner (23) sequentially aligns each row (32) of the tray (44) with a tube (48) of the reactor rod until all the pellets from tray (44) are loaded into the tube. This places the tray (44) into the unloaded tray position and established a reset signal along line (50) to the positioner (23) to move the tray (44) back to its original position, to have the positioner move back to alignment with the tray (32). To avoid the potential criticality of fuel pellets reaching a height in excess of 4 inches in the hopper (12), the conveyor could be coupled to prior art fuel trays received for loading coupled to a known unloading assembly which would feed the contents of a tray to the conveyor (26) for proper count and weight in the counter (24) and the weight tray (38) of the machine (10). The control elements and hardware needed to implement this system are well known in the automatic control area and details of same have been deleted herein for the sake of conciseness and readability but are fully intended to fall within the scope of the following claims.