Viking
Designing a Gamma Radiography System
Who we are.
• Gilligan Engineering Services est. 1988.
• Whole market experience - not tied to any manufacturers
equipment
• Very few new pieces of equipment launched onto the market.
• Close Proximity Radiography (CPR) is becoming more widely
used.
• In 2008 we decided to design and supply our own brand of
equipment.
Design Influences
1. Radiation Shielding Material:
An alternative to Depleted Uranium
2.
Safer:
Historical Incidents to avoid in the design
3.
New equipment for a new era:
Close Proximity Radiography while keeping flexibility
1. Radiation Shielding Material
Advantages of tungsten over DU
•
•
•
•
•
No health issues or risk of contamination spread
No end of life disposal issues
Easy to machine
No IAEA Safeguards reporting
No sheathing around the material required
1. Radiation Shielding Material
Challenges of using tungsten
•
•
•
•
Rumours of brittleness?
Can’t be cast in elaborate shapes.
Not as efficient for shielding compared to DU.
Relatively expensive
1. Radiation Shielding Material
• No signs of brittleness in the material testing
• Cooled to -40°C
• Impact mark from the drop.
• The impact had an energy
of 3.5kJ
• Resulted in a conventional
deforming of the impact edge
• No signs of brittleness.
1. Radiation Shielding Material
• The design of the radiation shield would have to be a simple shape.
• The shield should be as small as possible.
• This would give the optimum shielding to mass ratio
1. Radiation Shielding Material
• The design resulted in a camera that is physically small and compact.
• We have 6 different units based on the same layout and components
• Allows the size and weight of the camera to reflect the source strength
installed within.
1. Radiation Shielding Material
Challenges of using tungsten
•
•
•
•
Rumours of brittleness?
Can’t be cast in elaborate shapes.
Not as efficient for shielding compared to DU.
Relatively expensive
Design Influences
1.
Radiation Shielding Material:
An alternative to Depleted Uranium
2. Safer:
Historical Incidents to avoid in the design
3.
New equipment for a new era:
Close Proximity Radiography while keeping flexibility
2. Incident Avoidance
• Some of the typical incidents we have observed with all brands
of equipment over time are:
A. Butt connection
B. Source holder connection
C.
Registering the source is home - how the source operates
the Autolock.
2.A. Butt Connection
• A butt connection is a term for the equipment allowing
the source to be released from the camera and projected
from the shielded position without the source being
attached to the windout inner cable.
• It is easy to design a radiography system to resist a butt
connection and all equipment manufacturers do
• Butt Connections still occur in industry as a result of:
1. The equipment not been maintained correctly.
2. The equipment not been maintained within the
time laid down by the manufacturer.
2.A. Butt Connection
• In this state it is not possible to screw the nut onto
the equipment meaning the source can not be
released
• The Viking system source holder has been
designed to allow 8mm of wear of components
before a Butt Connection can occur.
2.B. Source holder connection
Incomplete Connection
• It should not be possible to operate the equipment with the windout
connector and source holder in a partially connected state.
2.B. Source holder connection
• The windout ball is depressing the plunger and the two components are
practically in line.
• This allows the windout to be connected to the projector while the
source holder is in this partially connected state which will probably later
lead to a disconnect.
2.B. Source Holder Connection
• Viking 3 point connection
1.
2.
3.
90° Insertion
Sliding backwards 1mm
Laying flat
2.B. Source Holder Connection
•
This combination ensures the source can not become detached in the
guide tube
CAD image
2.C. Source home on retraction
• Ensuring the source has returned home following the
exposure is of the upmost importance.
• ISO 3999 requires that the equipment gives an indicator
when the source has returned home.
2.C. Source home on retraction
• The end cap is the widest link on
the source holder
• The end cap houses the source
capsule
• The end cap is responsible for
operating the AutoLock
• If the AutoLock has operated the
source is home and shielded
End Cap
2.C. Source home on retraction
• It is always best practice to use a radiation monitor to verify
the source is home.
• Usually this is only ensuring there is low radiation levels in
the work area
• A further benefit of tungsten shielding however...
• A radiation monitor can detect the radiation emitted by
even a low energy isotope therefore allowing direct
monitoring of camera to confirm the source is inside.
2. Incident Avoidance
A.
B.
C.
•
Butt connection
Source holder connection
Registering the source is home - how the source operates the
Autolock.
The three addressed are a sample of many we considered while
designing the equipment:
Crushed control housing
Crushed guide tube
Run off
Premature AutoLock
operation
Windout connector failure
Outer housing swage failure
Securing the source in the
source holder
Source tube damage from
small drop
Spread of contamination
from worn S-tube
Design Influences
1.
Radiation Shielding Material:
An alternative to Depleted Uranium
2.
Safer:
Historical Incidents to avoid in the design
3.
New equipment for a new era:
Close Proximity Radiography while keeping
flexibility
3. Conventional CPR Advantages
• Lowers dose rates to non-radiation workers
• Results in less dose for radiographers and others.
• Speeds up a radiography production line by lowering delays
between processes
• Lower probability of incident occurrence and severity
3. Conventional CPR Challenges
• Slows down radiography due to prolonged setup.
• Limited selection of isotopes.
• Radiography jobs can not be conducted solely as CPR as access
for the equipment is limited
• A choice of mobilising two kits or carrying out the whole job as
projection
3. Viking Solutions
• Is very well suited but not limited to the use of Selenium-75 however it
can also be used with Ir-192 and Yb-169.
• Equipment eliminates the hot pass between source container and
collimator with out unique and patented tungsten chamfered face.
• Accessories designed in consultation with the end users – radiographers.
• This makes the equipment easy to use , flexible and encourages
radiographers to use CPR where they are able.
• It also allows more CPR in industry by lowering the cost of entry to
companies – they just need a single system and have CPR capability.
3. CPR Equipment
• Each Viking camera can be used as a projector or as a close proximity
container with the attachment of a large collimator.
• This is possible as the Tungsten shield does not need to be encased in a
secondary material.
3. CPR Equipment
• The accessories provided with the CPR system were designed in
consultation with radiographers to ensure efficient working.
3. Accessories - Positioning
• The CPR container is suspended from an
supporting strap
• Standoff is achieved using a flexible 3D arm or a
lightweight bracket
• A fast setup ensures CPR is cost effective as
well as safe.
3. Accessories - GammaShield
• GammaShield is a flexible and pliable radiation blanket.
• Can be used to form a movable wall of radiation
shielding.
• Flexible to bend around complex shapes such as
radiography projectors and pipe work.
• GammaShield is pliable allowing easy shaping and the
gives the ability of sheet to support itself.
3. Target Pad
• The Target Pad is an encased plate of lead for
attenuating the direct radiation.
• The component contains flanges to allow it to be
easily mounted.
• This is positioned behind the film and attenuates
a high degree of the primary radiation.
• Using the target pad takes the place of three
sheets of GammaShield which saves the
radiographer time.
Working with the System
Establishing and Monitoring an Area
Stand alone radiation detectors
• Ensuring proper signals are given to the
radiographer and other workers is vital
• We have developed an area monitoring system
• The PWS is a system of indicating the radiation
safety status of a work area.
• The system should ensure all points of access have
appropriate and correct signals shown and these
should be controlled from one centrally controlled
master unit.
Warning System – Radiation Detection
• The system features a radiation detector to be positioned next
to the container.
• When the detector picks up a high level of radiation all the
system lamps show a red light.
• Using the system like this ensures the barrier signals are correct
and they are always consistent with the radiation level within
the high radiation area.
Warning System - Lights and Sounders
• The warning system balances
automatic control and manual control.
– Amber (imminent) condition manually
operated
– High radiation at particular points gives
automatic red signal
Viking
A complete radiography system