The Van de Graaff Accelerator
The Van-de-Graaff Accelerator is a 5.5 MeV direct current positive ion accelerator used for research and training in the fields of Nuclear Science and Engineering. The particle accelerator is part of the Radiation Laboratory and operated on a full time basis.
All persons who desire to become an accelerator operator must first become familiar with its operation and potential hazards. Those individuals who plan to operate the accelerator must satisfactorily complete a training program conducted by the Accelerator Supervisor or his designee and must be approved by the Accelerator Safety Subcommittee as an accelerator operator. Any individual not authorized to operate the accelerator must work under the direct supervision of an authorized accelerator operator.
The Radiation Safety Office will conduct radiation surveys in the experimental work area to determine radiation levels and assess the overall radiological safety of the work area for all new experiments. All survey results will be maintained by the Radiation Safety Office.
The Accelerator Safety Subcommittee shall review all authorizations, changes in procedures, review of experimental work, and special accelerator related issues.
Operating Procedures and Conditions for the UMass Lowell Van-de-Graaff Accelerator
- Accelerator Start-up procedures
- Only those persons who have been authorized to operate the accelerator will have access to the key necessary to start the drive motor.
- Two persons from the accelerator staff will be in the accelerator control room, one of which shall be an accelerator operator and must remain in the accelerator control room at all times once the drive motor is engaged.
- A physical search and survey of the target and accelerator rooms will be carried out by the accelerator staff with the results reported to the accelerator operator.
- If the experiment protocol requires cooling the target with water, a visual check of the target cooling water flow will be made with the results reported to the accelerator operator.
- The basement entrance doors and the accelerator room gate interlocks will be checked (See section IV, items 1 and 2 and posted floor plans) with the results reported to the accelerator operator.
- Once all systems have been verified to be functional and the accelerator target and tank rooms verified to be free of unauthorized individuals, the accelerator operator will insert the drive motor key into the console and start up the accelerator. Upon initiation, a Klaxon horn, located in the target room and audible throughout the accelerator facility, will sound continuously for several seconds prior to starting the drive motor for accelerator startup.
- Lighted signs bearing the warning “Caution, High Radiation Area” posted over all entrances to the target room and tank room will remain on while the drive motor is energized.
- Accelerator Operations
- The accelerator console operator shall have quick access to the accelerator control room at all times.
- The console operator shall be responsible for visually monitoring and controlling access into the target room during accelerator operations.
- Entrance into the accelerator target room during accelerator operations shall conform to the procedures controlling entrance into a potential high radiation area within the accelerator facility (section c):
- Regulations Regarding Entrance to Potential High Radiation Areas within the Accelerator Facility
- Depending on the type of target used and the accelerator operating current, the Tower Room and the Target room are potentially high radiation areas during accelerator operations. Therefore the following safety procedures shall be followed by all personnel:
- Only individuals authorized by the Accelerator Safety Subcommittee shall enter the accelerator target room or tower room during acceleration operations (referred to as the HRA technician). The accelerator facility shall maintain a list of those individuals authorized for such entry.
- If access to a potentially high radiation area is desired during accelerator operations, a minimum of two accelerator personnel must be present with at least one person remaining in the accelerator control room.
- Prior to entry into these rooms, the authorized HRA technician is required to wear full radiation dosimetry including a whole body film badge and a hand/finger badge.
- The accelerator operator shall maintain constant communication with the authorized technician at all times while the person is within the target/tower room.
- Before entering the target/tower room, the HRA technician will survey the entrance area with an appropriate survey instrument to verify that the radiation fields are within expected levels.
- If radiation levels outside the entrance of the target/tower room are detected that are higher than those normally found under similar operating conditions, the HRA technician shall leave the area and alert the Radiation Safety Officer.
- While inside the target/tower room, the HRA technician will survey the working area with an appropriate survey instrument to verify that the radiation fields are within expected levels.
- If radiation levels inside the target/tower room are detected which are higher than those normally found under similar operating conditions, the HRA technician shall leave the target/tower room and alert the Radiation Safety Officer.
- After work in the room is complete, the HRA technician shall return to the control room and report to the console operator.
- Accelerator Shut-down
- The accelerator will be turned off by cutting power to the belt drive motor, thus preventing further emission of radiation, except from activated components.
- If all conditions appear normal, entrance into the accelerator target room will be made by personnel authorized by the operator.
- Any emergency condition shall be handled as outlined under the Emergency Plan.
- The cooling water will be checked.
- The drive motor key will be removed.
- Alarms and Safety Devices Incorporated in the Accelerator Complex.
- Failsafe electrical interlocks are positioned on all radiation area entrances not under the visual control of the console operator. These interlocks will automatically shut down the machine upon room access.
- The doors accessible in the control room which lead to the accelerator tank and target rooms are electro-mechanically interlocked such that, if opened during machine operations, an alarm will sound in the control room.
- The target room entrance is posted with the warning, “CAUTION, HIGH RADIATION AREA”. This sign will be lighted during accelerator operations.
- A red warning light in the target room will be lighted during operations.
- Neutron and gamma radiation levels in the target room will be monitored remotely at the accelerator console.
- Emergency shutdown switches are located in both the target room and accelerator room.
- A warning Klaxon horn will sound in the control room prior to accelerator start-up.
- Vacuum pump interlock switches will shutdown the machine if the vacuum system fails.
Under certain conditions specified by the Accelerator Safety Subcommittee, the accelerator may be operated by a single authorized individual. Under these circumstances the accelerator operator is prohibited access to the target room. Target room access during accelerator operations shall only be permitted when two or more accelerator personnel are present