When your work is completed and you are ready to exit, return to the entrance gates and press the intercom call switch to notify the MCC. Once you have entered and closed the first gate, each person must replace his key in the appropriate slot, otherwise the Personnel Safety System will not allow the master key to be released. When the master key is released, place it in its slot, and the MCC will unlock the final gate. When you have exited the final gate, make sure it has closed and locked behind you. If circumstances dictate, request that the MCC return the hall to the beam permit state and that beam be restored. It is important to note that if you need to work in the HRS shield house during the controlled access, you must go to the control room in the MCC before the access and get a special key which allows you to arm the run/safe box located in the shield house. The run/safe box inside the shield house will drop from the operational position to the safe position as soon as the door to the shield house opens. Unless this box is rearmed with the special key, the beam cannot run.