Making a Controlled Access Into a Hall

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At times, it may be necessary for hall personnel to enter a hall to investigate or repair a problem. If this is the case, the hall notifies the MCC Control Room, so that preparations can be made to make the hall safe for entry. This process takes about 10 minutes. Prior to entry, a radiation survey must be performed (this requirement is a little different for Hall B) and then specific access procedures must be followed. These steps are detailed below.

Radiation Surveys in the Halls

Halls A and C: To ensure personnel safety, radiation surveys must be performed by RadCon personnel or a qualified Assigned Radiation Monitor (ARM) before entering Hall A or Hall C. At the discretion of the person surveying the hall, hall personnel may be allowed into the hall under escort. If this is the case, the hall personnel must remain with the escort and must not enter any area that has not been surveyed.

Hall B: Because Hall B runs such low current and induces very little radiation, they utilize a "Rapid Access System" when making Controlled accesses. This system allows Hall B personnel to check the radiation levels inside the hall from the hall's entrance. A magenta beacon is located outside of the Hall B door. If the beacon is not flashing but turns on when the test button is pressed, it is safe to enter the hall. If the beacon is flashing and does not turn off after a few minutes or fails its function test, a full survey of the hall by RadCon or an ARM is required. During a Rapid Access, certain areas of the hall must not be entered. These areas are clearly posted, and if there is a need to enter, a survey of the area must be performed. Similarly, areas on or around the beampipe must be surveyed prior to beginning any work.

The Controlled-Access Procedure

After the hall has been surveyed (or the "Rapid Access System" has been tested in Hall B) and RadCon (or the ARM) has deemed the hall safe, personnel are free to enter the hall by following the Controlled Access procedure. During a Controlled Access, the doors remain locked (using magnetic locks) and entry is controlled remotely by the Safety System Operator (SSO) in the MCC Control Room. This allows the SSO to account for each person entering or exiting the hall. For this reason and to check for proper training, the following procedure must be followed when entering or exiting a hall under Controlled Access.


  1. Proceed to the hall entrance and, using the phone located at the entrance, call ext. 7050. The SSO will unlock the outer door to the hall.
  2. Enter the access room. The first person (or a member of a group) to enter the hall must take the Master Key out of its slot and put it in the empty slot below. The SSO must release the Master Key before it can be removed. This will release the other keys.
  3. Each person entering the hall must take a key (there are 10 keys) and keep it with them at all times.
  4. Call ext. 7050. Each person must give the SSO their full name (including spelling), the key number in their possession, show their radiation badge (TLD) (the camera is located in the access room), and indicate whether or not their ODH training is up to date. If a person's ODH training is not up to date, they can be escorted into the hall--one untrained person to each trained escort.
  5. After collecting the needed information from each person entering the hall, the SSO will open the inner door to the hall


  1. To leave, proceed to the hall exit door and call ext. 7050. The SSO will open the inner door.
  2. Enter the vestibule. Each person must reinsert their key into the appropriate slot. If a person (or group) is the last to leave the hall, the Master Key must be reinserted into its slot above the other keys.
  3. Call ext. 7050. Provide the SSO with the name of each person leaving the hall.
  4. The SSO will open the outer door.

If a detector hut door in either Hall A or Hall C has been opened during the Controlled Access, the MCC Control Room must be informed so that they can re-arm the hut's run/safe box and shut the hut door.

Once the Controlled Access has been completed, the hall should inform the MCC Control Room and request a return to Beam Permit. The operators will then take the hall to Power Permit, remove the hall beam stopper, turn on the hall magnetic dipole, and cycle the dipole through hysteresis. This entire process takes about 15 minutes. The operators will then send pulsed beam to verify that the orbit has not changed.