Core handling in heavy water reactors

Claim 1

IN A PROCESS FOR CORE HANDLING IN A SHUT-DOWN HEAVY WATER REACTOR THE STEPS COMPRISING: DRAWING-OFF THE HEAVY WATER FROM THE CORE AND CONFINING IT IN A TANK WHILE HEAVY WATER IS BEING SPRAYED OVER THE FUEL ELEMENTS; SPRAYING LIGHT WATER OVER THE FUEL ELEMENTS THEREBY WASHING OUT THE REST OF HTE HEAVY WATER, A MIXTURE OF HEAVY WATER AND LIGHT WATER THUS OBTAINED BEING COLLECTED AND CONFINED IN A CONTAINER; FILLING THE REACTOR WITH LIGHT WATER TO A PREDETERMINED LEVEL AFTER WHICH THE REACTOR IS OPENED AND AT LEAST PART OF THE CORE IS MOVED OUT OF AND A CORE IS MOVED INTO THE REACTOR IN THE WAY USED IN LIGHT WATER REACTORS; THEN CLOSING THE REACTOR AND DRAWING OFF THE LIGHT WATER FROM THE CORE WHILE LIGHT WATER IS SPRAYED OVER THE FUEL ELEMENTS; SPRAYING HEAVY WATER OVER THE FUEL ELEMENTS THEREBY WASHING OUT THE REST OF THE LIGHT WATER, A MIXTURE OF LIGHT WATER AND HEAVY WATER THUS