Four pin mounting system for nuclear reactor control rod guide tubes

摘要

A mounting system for removably mounting the lower flange of the control rod guide tube over an opening in the upper core plate of a nuclear reactor is disclosed. The system includes a pair of resilient pin members and a pair of reinforcing pin members. The resilient pin members are mounted in a passage formed through first opposing sides of the guide tube lower flange. They are resiliently receivable in first bores formed on first opposing sides of the upper core plate to permit deflection thereof when the guide tube is subject to normal shear loads. The resilient pin members bear substantially all of the normal shear load to which the guide tube is subjected. The reinforcing pin members are mounted on the second opposing side of the guide tube lower flange. They are receivable in second bores formed on the second opposing sides of the upper core plate with a clearance. The reinforcing pin members bear substantially all of the abnormal shear load that exceeds the normal shear load. The clearance between the reinforcing pin members and the second bores limits the deflection of the resilient pin members. After the resilient pin members deflect the distance limited by the clearance, the reinforcing pin members bear any additional abnormal shear loads and prevent the additional abnormal shear loads from bearing on the resilient pin members.