Shield Door Hydraulic System

These building structures are passive safety features and therefore perform passive safety functions. The only SSC whose mis-operation can directly affect the safety function of these structures is the shield door hydraulic system [a non-safety-reiated (NSR) system], which is used to lower and raise the massive shield doors connecting Rooms 108 and 109, and Room 109 and the Zone 2A canyon. Mis-opeiation of this system with the Room 109/Zone 2A shield door down and radioactive waste in Room 109, can present a radiation hazard to workers at the north end of Room 112. The Zone 2A canyon structures, including the associated shielding windows, and the Room 109 structures are the only HCF SSCs that are required to maintain their safety functions following an earthquake. 

The shield door hydraulic system controls provide a worker safety function by precluding the following unintentional door operations ... 

Administrative control of the hydraulic shield doors provides a worker safety function by 1) precluding lowering of the Room 108/109 shield door (door 2A) while the Room 101/108 shield door (door 1) is down, and 2) precluding lowering of the Room 109/Zone 2A shield door (door 3A) with workers in the Zone 2A canyon, the Zone 2A airlock, or the north end of Room 112. Keyed locks in the shield door hydraulic system control panel prevent unintended actuation of the shield doors. 

Shield Door Hydraulic System Controls Protection of HCF personnel from potentially lethal radiation exposures. HCF operators must ensure that shield door 1 is not lowered while shield door 2A is down and that shield door 3A is not lowered with workers In Zone 2A, the Zone 2A airlock, or the north end of Room 112. Administrative controls are in place to ensure adequate control of shield door operating keys. 

---