Spring lock washer for tie rod nuts.

摘要

In a nuclear fuel bundle, an improved lock washer is disclosed for permitting ease of remote removal of hex nuts on tie rods for the remote submerged disassembly of fuel bundles after use in a reactor. The improved lock washer includes two spaced apart and interconnected tie rod surrounding washer members (30,32), each having radially inwardly extending keys (40). These keys register to corresponding keyways (42) in the threaded ends (44) of the tie rods to prevent tie rod rotation and threaded disengagement from a tie plate at the other end. Each washer member is manufactured from a spring material and includes at least one and preferably two radially protruding tangs (50). These tangs are elongate and bent in an inverted U-shaped configuration, including a gradual inward slope (66) defining a gathering surface between the tie rod and bolt on one hand and the U-shaped tang on the other hand. From the end of the gathering surface, the tang extends vertically downward in a position of spring interference with one of the flat sides of the hexagonal bolt (72) holding the tie rod in place. When the tie rod washer is in place with the nut fastened, the tang prevents the bolt from turning responsive to vibration and upward force on the upper tie plate due to outflowing water and steam. In remote disassembly of the fuel bundle, the gathering surface permits the tang to be biased away from the sides of the bolt by a specialized nut-gripping socket that penetrates interstitially between the lock washer and nut and captures the nut when it is unscrewed. The lock washer because of its spring action returns to its initial shape after the socket and nut are removed.