METHOD AND DEVICE FOR PRODUCING UNCONTAMINATED MOX FUEL RODS Russian patent published in 2007 - IPC G21C21/02 

FIELD: production of uncontaminated mixed oxide fuel rods for atomic engineering.

SUBSTANCE: proposed method involves manufacture of uncontaminated MOX fuel rods from pellets in shielding chamber. The latter is held at pressure lower than indoor atmospheric value. Pellets are charged in stacked condition into can provided in advance with first plug on one of its two ends. Various structural components, such as hold-down spring, are charged. Second plug is installed on other end of can and held in position by circular weld, in particular when it is inserted in mentioned can without clamp. Parts of mentioned can or respective rod are at least once inspected for contamination. Safety chamber is divided into certain number of adjacent compartments. Each compartment communicates with adjacent one through sealed passage for can. Some of such passages are relatively aligned to provide for can movement along its longitudinal axis. Cans being charged with pellets are introduced with their open end forward into first compartment through sealed passage or inlet opening of compartment. Cans are moved along axis between sequential compartments until their open end occurs in last compartment. In the latter can is charged with pellets and, if necessary, with various structural members other than hold-down spring through its open end. Upon completion of charging can is partially pulled out along axis to transfer its open end to preceding compartment. In the latter can is at least partially cleaned and checked for probable contamination by pellets in the course of their charging or by atmosphere of last compartment. After that cans are moved to admit their open end to next compartment. Hold-down spring is installed and second plug is fitted in open end within this compartment. Then other required operations are made in this compartment or in another one involving additional movement of can. Parts of rod contaminated in last compartments are checked for condition and potentially decontaminated, as required, in first or second compartment. Rod is removed from first compartment or is crosswise displaced to other shielding chamber through first compartment that joins shielding chambers together. The degree of contamination stepwise changes between different compartments starting from no or negligible dirt in first compartment up to heavy contamination in last one. Gas supplied to these compartments is chosen from group incorporating air, nitrogen, helium, argon, and vacuum. Pressure within compartment is varied in steps to control leakage starting from high pressure in first compartment down to lowest pressure in the last one. In addition, device is proposed for producing uncontaminated MOX fuel rods.

EFFECT: enhanced safety for personnel engaged in manufacture of mixed oxide fuel rods.

19 cl, 12 dwg