Abstract: EMPLOYEE #1 WAS WORKING AS SET-UP OPERATOR IN A STERILE CORE WHERE CONRAY 30 WAS BEING PROCESSED. ON THE EVENING OF OCTOBER 7, 1986, EMPLOYEE #1 WAS CLEANING HOLD TANK #4 WHICH WAS A 6000 LITER CAPACITY STAINLESS STEEL TANK. CLEANING WAS TO BE PERFORMED ONLY FROM OUTSIDE THE TANK. EMPLOYEE #1 HAD BEEN INSTRUCTED NEVER TO ENTER A TANK. IF TANK ENTRY WAS NECESSARY, IT WAS TO BE DONE BY MAINTENANCE PERSONNEL IN ACCORDANCE WITH THE PROCEDURE FOR ENTERING TANKS AND ENCLOSED SPACES. APPARENTLY WHILE EMPLOYEE #1 WAS CLEANING THE TANK, A GASKET FELL INTO THE TANK. EMPLOYEE #1 ATTEMPTED TO RETRIEVE THE GASKET WITH A 4 FOOT LONG PIECE OF ANGLE IRON. WHEN THE ATTEMPT FAILED, EMPLOYEE #1 APPARENTLY ENTERED THE TANK TO RETRIEVE THE GASKET AND AN ANGLE IRON PIECE THAT HAD PROBABLY BEEN DROPPED. OTHER EMPLOYEES LATER FOUND EMPLOYEE #1, DEAD, IN THE BOTTOM OF THE TANK.