Transfer of fuel assemblies

Apparatus for removing and/or positioning fuel assemblies of a nuclear reactor during fueling, refueling or the like, the said apparatus including a crane, the said crane having:

• (a) a line termininating in a fixture to be engaged with a fuel assembly to be removed and to be disengaged from a fuel assembly positioned by said crane,
• (b) a line drive connected to said line to drive said line, and
• (c) a traverse drive for said crane,
• load-sensing means, connected to said line, for sensing the load on said line, setpoint means for setting a high-level load setpoint, a low-level load setpoint, and a slack-line setpoint, said high-level setpoint setting an upper limit on the loading of said crane when said line is raising a fuel assembly, said low-level setpoint setting a lower limit on the loading of said crane when said line is lowering a fuel assembly, said slack-line setpoint setting a limit dependent on the loading of said crane by said line and fixture alone, means, connected to said setpoint means and responsive to said load-sensing means, for disabling said line drive when the load on the crane exceeds said high-level setpoint, means, connected to said setpoint means and responsive to said load sensing means for disabling said line drive when the load on said crane is less than the low-level setpoint, means connected to said setpoint means and responsive to said load-sensing means, for disabling said traverse drive when the load on said crane exceeds said low-level setpoint, said traverse-drive disabling means including means for locking said traverse drive in the disabled condition, once the load exceeds the low-level setpoint, so that said traverse drive is not enabled if subsequent to such disablement of the traverse drive the loading on said crane is decreased to a magnitude between the low-level setpoint and the slack-line setpoint, and means, connected to said setpoint means and responsive to said load-sensing means, for disabling said traverse-drive locking means thereby enabling said traverse drive when the loading on said crane is less than the slack-line setpoint.

Apparatus for removing and/or positioning fuel assemblies of a nuclear reactor during fueling, refueling or the like, the said apparatus including a crane, the said crane having a line terminating in a fixture to be engaged with a fuel assembly to be removed and to be disengaged from a fuel assembly positioned by said crane, a line drive, connected to said line, to drive said line, load-sensing means, connected to said line, for sensing a load on said line, setpoint means for setting a high-level load setpoint and a low-level load setpoint, said high-level setpoint setting an upper limit on the loading of said crane when said line is raising a fuel assembly, said low-level setpoint setting a lower limit on the loading of said crane when said line is lowering a fuel assembly, first means, connected to said line drive and responsive to said load-sensing means, and a said setpoint means for disabling said line drive from raising said fuel assembly when the load on said crane exceeds said high-level setpoint, second means, connected to said line drive and responsive to said load-sensing means, and to said setpoint means, for disabling said line drive when the load on said line is less than the low-level setpoint, bypass means, connected to said first means, for overriding said high-level setpoint and enabling said line drive to raise said fuel assembly notwithstanding that said high-level setpoint is exceeded, said bypass means being operable by a key which cannot be removed from the key slot unless said key is turned to the non-bypassing setting, and signaling means for signaling that said first means is bypassed.