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Our
Capabilities
Nuclear Excellence Since 1976
WITT UK Group stands as one of the elite manufacturers globally qualified for nuclear ventilation systems, with proven installations in over 58 nuclear facilities worldwide including power plants, research reactors, fuel fabrication facilities, and reprocessing plants. Our nuclear pedigree spans nearly five decades, maintaining KTA 1401 certification for nuclear quality assurance since 1976, alongside specialised authorisations including W 180.11/1-RS under §15 of the Radiation Protection Ordinance. This enables our qualified personnel to work within controlled areas, performing installation, maintenance, and decommissioning activities in radioactive environments. From Pressurised Water Reactors (PWR) to Boiling Water Reactors (BWR), from Advanced Gas-cooled Reactors (AGR) to Small Modular Reactors (SMR), our ventilation systems protect workers, the public, and the environment through multiple barriers of containment and filtration. Our UK nuclear experience includes Hinkley Point C new build project, Sizewell B lifetime extension, Sellafield reprocessing facilities, and decommissioning projects across Magnox sites.
Uncompromising Safety & Reliability
Nuclear ventilation demands absolute reliability—failure is not an option when managing radioactive containment, reactor cooling, and emergency response systems. Our nuclear-grade fans incorporate defence-in-depth principles with multiple redundancy levels, diverse actuation systems, and fail-safe designs ensuring safety functions despite component failures. Every system undergoes exhaustive qualification including seismic analysis to IEEE 344 and European standards, environmental qualification for Design Basis Accidents (DBA), radiation ageing tests to 10⁸ Gy total integrated dose, and Loss of Coolant Accident (LOCA) simulation. Materials selection addresses 60-year design life with austenitic stainless steels resisting radiation embrittlement, decontaminable surfaces enabling maintenance in hot zones, and qualified coatings preventing radioactive particle adhesion. Documentation packages meet regulatory scrutiny with full traceability from ore to installation, comprehensive design basis justification, Independent Nuclear Safety Assessment (INSA) support, and through-life configuration management. Whether ventilating reactor containment, managing spent fuel pool environments, or providing filtered emergency venting, our systems represent the gold standard in nuclear safety engineering.
- 58+ nuclear installations worldwide across all reactor types
- KTA 1401 and ASME N-stamp nuclear quality programmes
- Seismic qualification to SL-2/SSE earthquake levels
- 60-year qualified design life with ageing management
- Class 1E safety systems with 99.99% availability
- Radiation-qualified personnel for controlled area work
Why Choose
Axial Flow Fans
PROVEN PEDIGREE
Five decades of nuclear excellence with KTA 1401 certification since 1976.
SAFETY QUALIFIED
Seismic, environmental, and radiation qualification meeting international nuclear standards.
LIFECYCLE PARTNERSHIP
60-year design support from new build through decommissioning with qualified personnel.
Frequently
Asked Questions
What makes nuclear ventilation different from conventional systems?
Nuclear ventilation operates to fundamentally different standards reflecting radiological hazards and safety implications. Every component requires nuclear-grade qualification with documented pedigree from raw materials through manufacture. Design basis must address normal operation plus Design Basis Accidents including LOCA, seismic events, and station blackout. Materials must withstand radiation exposure—typically 40-year doses exceeding 10⁶ Gy—without degradation. Construction enables decontamination for maintenance in radioactive areas using electropolished stainless steel and strippable coatings. Quality assurance follows nuclear standards (KTA, ASME, RCC-M) with hold points, witness testing, and regulatory oversight. Documentation packages can exceed 10,000 pages including calculations, test reports, and certificates. This rigorous approach ensures public safety through multiple barriers preventing radioactive release.
How is seismic qualification achieved for nuclear fans?
Seismic qualification ensures safety systems remain functional during and after earthquakes, critical for reactor shutdown and cooling. The process involves seismic analysis using finite element methods determining stress levels and deflections. Response spectra analysis confirms natural frequencies avoid resonance with earthquake frequencies. Shake table testing validates analytical predictions using scaled or full-size units. Testing demonstrates structural integrity—no breach of pressure boundary—and functional capability maintaining required flow and pressure. We qualify to Operating Basis Earthquake (OBE) for continued operation and Safe Shutdown Earthquake (SSE) for safety functions. Multi-axis testing simulates real earthquake motion including vertical acceleration. Post-seismic inspection confirms no degradation requiring immediate functionality. Documentation includes test reports, video evidence, and regulatory witness statements.
What are the different ventilation zones in a nuclear plant?
Nuclear plants employ zoned ventilation maintaining pressure cascades preventing radioactive release. Zone 1 (white) areas have no contamination risk, requiring standard industrial ventilation. Zone 2 (green) represents potentially contaminated areas with filtered supply and extract maintaining negative pressure. Zone 3 (amber) covers contaminated areas requiring HEPA filtration, airlock entry, and continuous monitoring. Zone 4 (red) includes high-radiation areas like reactor containment with redundant filtration, iodine adsorbers, and emergency isolation. Each zone requires specific fan characteristics: gas-tight construction preventing cross-contamination, decontaminable surfaces for maintenance, radiation-resistant materials and lubricants, and remote monitoring minimising personnel exposure. Pressure differentials cascade from clean to contaminated areas, ensuring any leakage flows toward higher contamination zones.
How do nuclear fans handle Design Basis Accidents?
Design Basis Accidents (DBAs) represent credible scenarios nuclear systems must withstand whilst maintaining safety functions. Loss of Coolant Accident (LOCA) conditions include 100% humidity at 150°C+ with radiation spikes and pressure transients. Our fans demonstrate continued operation through environmental qualification testing simulating accident conditions. Station Blackout requires battery-backed operation or passive cooling maintaining decay heat removal. External hazards include seismic events, aircraft impact, and extreme weather requiring robust construction and diverse locations. Post-accident operation may extend months in harsh conditions—high radiation, temperature, and humidity—demanding qualified components and materials. Containment ventilation must handle hydrogen generation preventing explosive concentrations through mixing or recombiners. Each accident scenario undergoes detailed analysis ensuring ventilation maintains required safety functions.
What documentation is required for nuclear projects?
Nuclear documentation provides comprehensive evidence of safety and quality throughout component lifetime. Design packages include calculations (structural, thermal, seismic), safety case contributions, and design basis justification. Manufacturing documentation covers material certificates with chemical/mechanical properties, procedure qualifications for welding and NDE, dimensional reports and pressure tests, and quality plans with hold/witness points. Testing generates seismic qualification reports, environmental qualification dossiers, factory acceptance test records, and site acceptance test results. Operational documentation includes operating and maintenance instructions, spare parts recommendations with storage requirements, ageing management programmes, and modification procedures maintaining design basis. Every document requires formal approval through nuclear quality systems with independent verification, regulatory review, and lifetime retention—typically 60+ years. This documentation mountain ensures traceability, supports periodic safety reviews, and enables knowledge transfer across generations.
How is nuclear ventilation maintained in radioactive areas?
Maintaining ventilation equipment in radioactive areas requires sophisticated planning minimising dose whilst ensuring reliability. Our radiation-qualified personnel hold §15 authorisation enabling controlled area work with appropriate training, dosimetry, and medical surveillance. Design features facilitate maintenance including quick-release mechanisms reducing exposure time, remote monitoring avoiding area entry, modular construction enabling component exchange, and decontamination provisions for hot maintenance. Work planning follows ALARA principles (As Low As Reasonably Achievable) using mockups for training, temporary shielding reducing dose rates, contamination control preventing spread, and remote tools minimising direct contact. Outage coordination integrates with reactor shutdown schedules when radiation levels decrease. Post-maintenance testing confirms performance without compromising contamination barriers. Our nuclear service team provides complete support from routine maintenance through major overhauls and eventual decommissioning, ensuring systems protect workers and public throughout nuclear facility lifecycle.