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Cyclotron Bunker Plug Door, Shielded Door
The Madoors USA Cyclotron Bunker Plug Door is a world-leading shielded door system specifically engineered for hot shielded cyclotron facilities, particle accelerator vaults, radiotherapy bunkers, and nuclear medicine installations requiring maximum radiation shielding performance combined with reliable, safe, and smooth automated operation. Constructed as a steel formwork entirely filled with concrete or high-density barytic concrete casting, and available with lead, paraffin, polyethylene, and cadmium shielding materials in various thicknesses, the Madoors USA cyclotron bunker plug door provides a complete radiation shielding solution designed by technical experts to match the specific shielding requirements and dimensional constraints of each facility.
Movement is operated by a wheel system connected to an electric gear motor or hydraulic motor, controlled by an inverter ensuring mild, linear operation with acceleration and deceleration ramps — providing gentle, controlled door movement that protects the door structure and surrounding facility from shock loading during the opening and closing cycle. The double-tooth formwork design provides perfect coupling with the surrounding wall structure, and the full-perimeter silicon ring seal is completely compressed when the door is closed — providing superior sealing of the depression inside the protected premises.
TECHNICAL SPECIFICATIONS
The Madoors USA Cyclotron Bunker Plug Door is constructed from a steel formwork entirely filled with concrete or barytic concrete casting. Barytic concrete — incorporating barium sulfate aggregate — provides significantly higher density than standard concrete, delivering superior gamma radiation attenuation in a reduced door thickness compared to standard concrete fill — a critical design advantage where available door pocket space constrains maximum door thickness. Standard concrete fill is available for applications where door pocket space permits the thickness required for adequate shielding without the higher cost of barytic concrete.
The steel formwork is designed with a double-tooth profile that overlaps with the surrounding wall structure when the door is closed. A steel frame is supplied separately to form the female double-tooth receiving profile in the wall opening, ensuring perfect coupling between the door and wall with reduced clearance at the tooth interface — minimizing the radiation streaming path through the door-to-wall joint that would otherwise create a radiation leakage pathway around the shielded door body.
The full inside perimeter of the door incorporates a silicon ring seal that is completely compressed when the door reaches the closed position, providing higher sealing of the depression inside the premises. This perimeter seal serves both radiation containment and air pressure sealing functions — maintaining the internal atmospheric conditions of the cyclotron vault and preventing radiation streaming at the door perimeter.
The movement system uses a wheel-based rolling mechanism to translate the heavy door mass along the plug door travel path. Drive options include an electric gear motor and a hydraulic motor — with the motor controlled by an inverter providing variable frequency drive for smooth acceleration and deceleration ramps. Inverter control eliminates the shock loading of direct motor start and stop, extending the service life of the wheel system and door structure under the high-cycle operational demands of clinical cyclotron facilities.
Shielding materials available in addition to concrete and barytic concrete include lead, paraffin and/or polyethylene, and cadmium — selectable individually or in combination based on the radiation type and energy level requiring attenuation. Paraffin and polyethylene provide hydrogen-rich neutron moderation for neutron shielding applications. Cadmium provides thermal neutron capture. Lead provides gamma ray attenuation. Combined shielding configurations address mixed radiation fields — as generated by cyclotron targets — where both gamma and neutron shielding are simultaneously required.
KEY FEATURES
World-Leading Shielded Door Manufacturer
Madoors USA is the world's leading manufacturer for the production of shielded doors — bringing the deepest available commercial expertise in radiation shielding door design, material selection, and installation to every cyclotron bunker plug door project. This world-leading position reflects decades of experience across the full range of radiation shielding door applications, from medical cyclotron vaults through to high-energy physics research facilities and nuclear medicine treatment rooms.
Steel Formwork with Concrete or Barytic Concrete Fill
The steel formwork construction provides the structural frame that contains and supports the concrete or barytic concrete fill, maintaining the door geometry and surface finish while the dense concrete mass provides the primary radiation attenuation. Barytic concrete fill delivers higher density — typically 3,200 to 3,500 kg/m³ versus 2,300 kg/m³ for standard concrete — providing superior shielding performance per unit of door thickness and enabling thinner door designs where vault space is constrained.
Double-Tooth Formwork — Radiation Streaming Prevention
The double-tooth design at the door-to-wall interface creates an interlocking overlap that prevents direct line-of-sight radiation streaming through the gap between the door edge and the surrounding wall. Without the double-tooth geometry, even a small gap between the door and wall would create a direct radiation pathway that bypasses the full shielding thickness of the door body. The double-tooth with reduced clearance eliminates this streaming pathway, ensuring that radiation must pass through the full combined shielding thickness of the door and wall at every point around the door perimeter.
Steel Frame Female Double-Tooth — Perfect Coupling
The separately supplied steel frame produces the female double-tooth receiving profile in the wall opening, providing a precision-manufactured mating surface for the door double-tooth that ensures perfect coupling with reduced clearance throughout the service life of the door — maintaining consistent streaming prevention performance across thousands of open and close cycles without dimensional drift from wear.
Full-Perimeter Silicon Ring Seal — Depression Sealing
The full inside perimeter silicon ring seal is completely compressed when the door is in the closed position, providing a continuous gas-tight and radiation-tight seal around the entire door perimeter. This complete perimeter compression seals the depression — the negative pressure maintained inside the cyclotron vault to prevent radioactive gas release — and prevents radiation streaming at the seal interface throughout the closed cycle.
Inverter-Controlled Drive — Smooth Acceleration & Deceleration
The inverter-controlled motor drive provides variable frequency operation with programmable acceleration and deceleration ramps, ensuring that the heavy concrete-filled door mass accelerates and decelerates smoothly at the start and end of each travel cycle — preventing mechanical shock loading on the wheel system, door structure, and surrounding wall interface that would occur with direct motor start and stop on a door of this mass.
Electric Gear Motor & Hydraulic Motor Options
Two motor drive options cover different power infrastructure and operational preference requirements. The electric gear motor provides reliable, electrically efficient drive for facilities with adequate electrical supply infrastructure. The hydraulic motor option provides high-force output for the largest and heaviest door configurations, with consistent force delivery independent of electrical supply fluctuations that could affect motor torque at critical acceleration phases.
Lead, Paraffin, Polyethylene & Cadmium Shielding Materials
The full range of radiation shielding materials — lead for gamma attenuation, paraffin and polyethylene for neutron moderation, and cadmium for thermal neutron capture — is available individually or in combination within the door construction. Multi-material shielding configurations address the complex mixed radiation fields generated by cyclotron targets, where gamma radiation and neutron radiation of varying energies must be simultaneously attenuated to achieve the required dose rate outside the vault.
Custom Shielding Design by Technical Experts
Madoors USA's technical experts design the most suitable and cost-effective shielding solution for each specific cyclotron installation — calculating the required shielding material combination and thickness based on the beam energy, target material, beam current, occupancy factors, and regulatory dose rate limits applicable to the specific facility. This expert-designed, project-specific shielding specification ensures that the door provides exactly the required attenuation without unnecessary over-specification that would increase door weight and cost.
Safety Device Priority — Maximum Operator Safety
Top priority is given to safety devices in every Madoors USA cyclotron bunker plug door installation — ensuring that all personnel safety requirements for the heavy automated door are addressed, including obstruction detection, emergency stop, access control interlocking with the cyclotron beam control system, and visual and audible warning systems. Maximum operator safety is the primary design principle for all safety device specifications.
SHIELDING MATERIAL SELECTION GUIDE
Concrete Fill — Standard shielding for gamma radiation at cyclotron beam energies where door thickness is not constrained. Suitable for lower beam energy facilities and secondary shielding applications.
Barytic Concrete Fill — High-density gamma shielding for space-constrained vault designs where maximum shielding must be achieved in minimum door thickness. Density 3,200–3,500 kg/m³ versus 2,300 kg/m³ for standard concrete.
Lead Shielding — High atomic number gamma attenuation for applications requiring maximum gamma shielding in minimum thickness. Combined with concrete or barytic concrete in composite door constructions.
Paraffin and/or Polyethylene — Hydrogen-rich neutron moderation and fast neutron thermalization for cyclotron facilities producing significant neutron fields from proton beam-target interactions. Essential for high-energy proton cyclotron applications.
Cadmium — Thermal neutron capture layer positioned after the neutron moderating layer to capture thermalized neutrons before they exit the shielded door. Combined with paraffin or polyethylene in neutron shielding composite door constructions.
Combined Multi-Material — For cyclotron facilities with complex mixed radiation fields where sequential gamma attenuation, fast neutron moderation, and thermal neutron capture must all be addressed within the door construction.
ASSEMBLY & INSTALLATION SEQUENCE
Shielding Calculation & Door Specification
Beam energy, target material, beam current, radiation field characterization, regulatory dose rate limits, and occupancy factors are provided by the facility radiation protection officer or medical physicist. Madoors USA technical experts calculate the required shielding material combination and thickness. Door dimensions, weight, and movement system specification are confirmed.
Female Double-Tooth Frame Installation
The steel frame producing the female double-tooth profile is installed in the vault wall opening at the specified position. Frame alignment, plumb, level, and embedding into the surrounding shielding wall structure are verified to the engineering tolerances required for perfect coupling with reduced clearance.
Wheel Track & Drive System Installation
The wheel track system is installed along the door travel path. The electric gear motor or hydraulic motor with inverter control is installed at the specified drive position. Motor-to-wheel drive connection and inverter parameter programming — acceleration ramp, deceleration ramp, travel speed — are configured.
Steel Formwork Construction
The steel door formwork is fabricated to the confirmed dimensions with the double-tooth profile at the door perimeter and all embedded hardware — wheel axles, silicon ring seal groove, lifting points, and motor connection — installed within the formwork before concrete casting.
Concrete or Barytic Concrete Casting
Concrete or barytic concrete is cast into the steel formwork in a controlled process to ensure full cavity filling without voids that would create local shielding deficiencies. Casting is completed in layers where door thickness requires multiple pours for proper consolidation. Curing is completed to the specified concrete strength before the door is moved.
Shielding Material Layer Installation (Lead, Paraffin, Polyethylene, Cadmium)
Where multi-material shielding is specified, lead plates, paraffin blocks, polyethylene panels, and cadmium sheets are installed within the formwork at the specified positions and thicknesses before or during the concrete casting sequence, creating the composite shielding layer assembly within the door body.
Silicon Ring Seal Installation & Compression Verification
The full-perimeter silicon ring seal is installed in the seal groove within the door body. Door-to-frame closure is tested to verify complete silicon ring compression across the full perimeter in the closed position, confirming the integrity of the depression seal.
Drive Commissioning & Safety System Testing
The motor drive is commissioned with inverter acceleration and deceleration ramp settings verified for smooth, controlled door travel from rest to operating speed and back to rest. All safety devices — obstruction detection, emergency stop, beam interlock, and warning systems — are installed, connected, and tested. Cyclotron beam interlock interface with the door position sensing system is verified.
Radiation Survey & Certification
A radiation protection survey is conducted with the door in the closed position to verify that the installed door achieves the required dose rate attenuation at all monitoring positions outside the vault. Survey results are documented and compared against the regulatory dose rate limits for the facility. Certification documentation is compiled for the facility radiation protection authority.
DEPLOYMENT SCENARIOS & USE CASES
Madoors USA Cyclotron Bunker Plug Doors are specified for any radiation-generating facility requiring heavy plug door shielding at vault access openings.
- Medical cyclotron vault plug doors for radiopharmaceutical production
- Proton therapy treatment room vault plug doors
- Radiotherapy linear accelerator vault plug doors
- Nuclear medicine PET cyclotron facility bunker doors
- High-energy physics research cyclotron vault doors
- Neutron therapy facility vault plug doors
- Isotope production hot cell bunker access doors
- Synchrotron and particle accelerator experimental area plug doors
- Nuclear research reactor access shielded plug doors
- Industrial gamma irradiation facility vault plug doors
- Non-destructive testing radiation facility bunker doors
- Radiation calibration laboratory vault plug doors
- Veterinary radiotherapy facility bunker access doors
- University research cyclotron facility vault doors
- Radiological emergency response facility shielded doors
- Category: Sliding Gate