Radiation safety training for controlled areas

The training below is required for unaccompanied access to accelerator areas and beamline hutches (controlled areas). It is an extension to the radition safety training for protected areas. Note that the training below is only required if access to controlled areas is needed.

1. Access to accelerator areas

Accelerator areas constitute controlled areas where radiation levels may be significant. There are four main accelerator areas at MAX IV: the linac tunnel, the short pulse facility (SPF), the 1.5 GeV ring tunnel and the 3 GeV ring tunnel. In addition, there are two smaller accelerator areas used for test purposes: the gun test room and the cavity test room.

All entry points, including concrete doors, leading into an accelerator area are marked “Kontrollerat område” (controlled area) and are equipped with switches that turn off the source of the ionizing radiation (accelerator/ring) should the door be opened during operation. Doors to accelerator areas are locked and an access card is required to unlock them. This only works if the source is off. The access card will not unlock the corresponding door if the source is on. The radiation hazard status and access status is indicated by lights above both the regular and concrete doors.

The door is unlocked by swiping the access card at the tag reader marked “IN”. If several persons enter at the same time, each person must log in separately by swiping their access card. During visits, it is sufficient if the person responsible for the group logs in.

Instructions are posted at the entrances to the accelerator areas describing how to enter and under what conditions entry is allowed. These instructions must be studied before entry.

acc_dörr_liten

The picture above shows the entrance at the start of the linac tunnel. Access is only allowed if the green light above the door is lit. The orange light flashes when a search procedure in the area behind the door is in progress and is lit when the search is complete. The red light indicates that a radiation hazard is present in the area behind the door.

In addition, lasers are utilized in some areas, such as the linac tunnel. The blue light above the door is lit when a laser hazard is present in the area behind the door.

The doors are not locked from the inside, so exiting is always possible. In the event of an emergency, it is always possible to open the door from the outside by breaking the plastic cover and using the emergency thumbturn. The accelerator/ring will turn off as soon as the door is opened, as the red switch is connected to the personnel safety system and detects an open door.

EPD

An electronic dosimeter (pictured above) must be carried within accelerator areas and is available at the entry points. The electronic dosimeters are always on and you should only check that the battery is OK, i.e. dose information is shown on the display. The dosimeter shows the accumulated dose and, after pressing its button once, the current dose rate.

During visits, it is sufficient if the person responsible for the group carries an electronic dosimeter.

Specific training is required for operating the concrete doors, as they constitute a crush hazard. Additional instructions are posted on the concrete doors. The access rules regarding logging in at an entrance and carrying an electronic dosimeter applies also when entering an accelerator area through an open concrete door.

2. Inside accelerator areas

Accelerator areas are normally segmented and passage between two adjacent segments is only allowed through the designated door.

segmented controlled area
Segmentation of an accelerator area, in this case the linac, with designated door for passage between adjacent segments.

In some cases a radiation hazard might be present on one side of a fence while access is allowed on the other side. This is indicated when the red lamp is lit above the then locked door. In the event of an emergency, it is always possible to unlock the door by pressing the black emergency door release button.

Panels are located within the accelerator areas. They contain two sirens and warning lights for laser hazard (blue, not in all areas), radiation hazard (red) and search status (orange). Some panels also have a status overview of all accelerator areas. Buttons related to the search procedure are located at the bottom of the panel, along with an emergency stop. The emergency stop shuts down all radiation and laser sources. The emergency stop also shuts down some of the insertion devices and a small number of the largest magnet power supplies.

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A panel containing warning lights, sirens, search button(s) and an emergency stop.

One of the sirens is active during the search procedure and has a long alarm period with a varying pitch. The other siren has a short alarm period with a constant pitch and is active for 30 seconds when the radiation or laser sources start.

A radiation hazard (red) and laser hazard (blue) may only be present in an area that has been searched. Thus, no one is expected to see these warning lights lit while inside an accelerator area. You must immediately exit the area and tell others to do the same should you see one of these two lights lit. Press an emergency stop on your way out and call the radiation safety team as soon as you have exited the accelerator area. This also applies should you hear the siren with the short alarm period.

In addition, the following also applies:

  • You must immediately exit the area if an electronic dosimeter alarm is triggered and tell others to do the same. Press an emergency stop on your way out and call the radiation safety team when you are out of the accelerator area. The alarm is most likely due to induced activity (see section 4).
  • The accelerator area has to be searched before the accelerator/ring can be started. The orange light flashes and the siren with the long period is active during the search procedure. You should then quickly exit the area. If this is not possible, you should press an emergency stop, which will abort the search procedure.

 

3. Exiting accelerator areas

Everyone has to swipe their access card at the “IN” tag reader before entering an accelerator area and again at the “UT” (out) tag reader upon exit. The personnel safety system keeps track of the number of people remaining in the area and the accelerator/ring cannot be started unless everyone has logged out. Additionally, the controlled areas have to be searched before the accelerator/rings is can be started. It is possible to log out at a different entry point than where you logged in if the accelerator area has several entry points. For the two small accelerator areas (the gun test room and the cavity test room) there is no entry/exit log and log out is not required upon exit.

Return the electronic dosimeter at the exit point when leaving the accelerator area.

4. Induced activity

Material close to the electron path might be activated. Before handling this material or working in its proximity, put the electronic dosimeter directly on the material to be worked on and measure for approximately one minute. If the dosimeter does not trigger an alarm, the activity is low and the risk of handling the material is low. Contact the radiation safety team if an alarm is triggered or if you have any questions.

Material that is to be removed from the accelerator/ring enclosures for use at other locations within the lab, or is to be moved off-site, must be checked for activation by the radiation safety team. This applies to material present within an accelerator area while the accelerator/ring was in operation. The degree of activation depends on factors such as the area the material was located in, type of material and the distance between the material and the electron path. For the two small accelerator areas (the gun test room and the cavity test room) the electron energy is too low to induce any activation.

An alternative to contacting the radiation safety team before removal of material from accelerator areas is to deposit the material in dedicated containers, which are located by the main entrances leading into the accelerator areas.

All items must be marked with the designated labels available on the containers.

tunna_liten
Container for deposition of material from accelerator areas.

5. Access to beamline hutches

The radiation levels inside the optics hutches of the beamlines can be very high, and these areas are thus classified as controlled areas. This also applies to the experimental hutches of the hard x-ray beamlines at the 3 GeV ring. The procedure for access is similar to that for entry to accelerator areas.

All entry points leading into the hutches are labeled “Kontrollerat område” (controlled area) and are equipped with switches that turn off the source of the ionizing radiation (accelerator/ring) and close the beam shutters should the door be opened when radiation hazard may be present in the hutch. Doors to the hutches are locked and an access card is required to unlock them. This only works if there is no radiation hazard in the hutch, i.e. if the front-end beam shutters are closed for the optics hutch and the monochromatic beam shutters are closed for the experimental hutch. If the beam shutters are open the access card will not unlock the corresponding door. The radiation hazard status and access status is indicated by lights above the doors.

The door is unlocked by swiping the access card at the tag reader. At the beamline hutches at the 1.5 GeV and 3 GeV rings a green and a red light next to the tag reader indicates if the attempt to unlock the door was successful or not.

Instructions are posted at the entrances to the hutches describing how to enter and under what conditions entry is allowed. These instructions must be studied before entry.

The picture below shows the entrance to an experimental hutch. Access is only allowed if the green light above the door is lit. The orange light flashes when a search procedure of the area behind the door is in progress and is lit when the search is complete. The red light indicates that a radiation hazard is present in the area behind the door.

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In addition, at some beamlines were lasers are used, e.g. FemtoMAX, an additional blue light above the door is lit when a laser hazard is present in the area behind the door.

The doors at the 3 GeV ring beamline hutches are locked by electromagnetic locks. These doors are locked both from the outside and the inside of the hutch. In the event of an emergency, it is always possible to unlock the door by pressing the black emergency door release button.

The doors at the 1.5 GeV ring and SPF beamline hutches are not locked from the inside, so exiting is always possible. In the event of an emergency, the doors can be opened from the outside by breaking the plastic cover and using the emergency thumbturn.

EPD

An electronic dosimeter (pictured above) must be carried within the hutches and is available at the entry points. The electronic dosimeters are always on and you should only check that the battery is OK, i.e. dose information is shown on the display. The dosimeter shows the accumulated dose and, after pressing its button once, the current dose rate.

During visits, it is sufficient if the person responsible for the group carries an electronic dosimeter.

6. Inside beamline hutches

Panels are located within the hutches. They contain two sirens and warning lights for radiation hazard (red) and search status (orange). At some of the beamlines with lasers, an additional blue light indicates laser hazard.

panel_hutch
A panel inside a beamline hutch, containing warning lights and sirens.

Inside the hutches, there are also buttons related to the search procedure and emergency stops. The emergency stops shut down all radiation sources. The emergency stops also shut down some of the robots and laser sources.

One of the sirens is active during the search procedure and has a long alarm period with a varying pitch. The other siren has a short alarm period with a constant pitch and is active for 30 seconds when the search has been completed and when the beam shutters are opened.

A radiation hazard (red) may only be present in a hutch that has been searched. Thus, no one is expected to see these warning lights lit while inside the hutch. You must immediately exit the hutch and tell others to do the same should you see the red lights lit. Press an emergency stop on your way out and call the radiation safety team after you have exited the hutch. This also applies should you hear the siren with the short alarm period.

In addition, the following also applies:

  • You must immediately exit the hutch if an electronic dosimeter alarm is triggered and tell others to do the same. Press an emergency stop on your way out and call the radiation safety team when you have exited the hutch.
  • The hutch has to be searched before radiation can be present. The orange light flashes and the siren with the long alarm period is active during the search procedure. You should then quickly exit the area. If this is not possible, you should press an emergency stop, which will abort the search procedure.
  • Even though it is possible for anyone to search a hutch, a specific training must be completed in order to be permitted to carry out a search procedure. This training is currently provided by the radiation safety team.

 

7. Exiting beamline hutches

At the 1.5 GeV ring and SPF beamline hutches, the doors are always unlocked from the inside.

At the 3 GeV ring beamline hutches, the doors are locked by electromagnetic locks. To unlock the door from the inside, press the button with the key symbol. In the event of an emergency, it is always possible to unlock the door by pressing the black emergency door release button.

3GeV door buttons
Buttons to unlock the door at a 3 Gev beamline hutch. The black button is to be used only in the event of emergency.

Return the electronic dosimeter after exiting the hutch.

Note that the beamline related information above only applies to beamline hutches that are in operation. Beamline hutches that are not yet in operation are classified as protected areas, which is highlihghted by separate signs at the respective entrances.