Reactor shut-down apparatus using neutron absorbing balls

Claim 1

FOR INSTALLATION IN A NUCLEAR REACTOR FOR SHUT-DOWN THEREOF, RESTRAINT MEANS FOR RELEASABLY RESTRAINING A MULTIPLICITY OF DISCRETE BODIES THE MATERIAL OF WHICH AT LEAST INCLUDES MAGNETIC MATERIAL AND WHICH POSSESS NEUTRON ABSORBING PROPERTIES, SAID RESTRAINT MEANS COMPRISING AT LEAST ONE PAIR OF MAGNETIC POLE PIECES OF OPPOSITE POLARITY AND COMPRISING PART-CYLINDRICAL SURFACES, NON-MAGNETIC FILLETS SEPARATING ADJACENT POLE PIECES, SAID POLE PIECES AND SAID FILLETS PROVIDING IN COMBINATION A HOLLOW CYLINDRICAL PASSAGE MOST OF WHOSE WALL IS FORMED BY IS FORMED BY A SURFACE OF EACH SAID FILLET, SAID PASSAGE BEING DISPOSED WHEN IN OPERATIVE POSITION WITH ITS AXIS HAVING AT LEAST A SUBSTANTIAL VERTICAL COMPONENT AND FORMING A CONTAINER FOR SAID BODIES IN WHICH SAID BODIES ARE RESTRAINED BY MAGNETIC FORCE AGAINST MOVEMENT ALONG SAID PASSAGE, WHEREBY DEMAGNETISATION OF SAID POLE PIECES SERVES TO RELEASE SAID BODIES FOR MOVEMENT UNDER GRAVITY ALONG AND OUT OF SAID PASSAGE FOR TRANSMISSION INTO A REACTOR CORE.