ATEX study with CFD & HVAC engineering for nuclear waste storage

Context:
At a nuclear site with storage and monitoring buildings for low- and intermediate-level waste, hydrogen gas (H₂) can be generated by radiolysis. Controlling explosion risks required an integrated approach: an ATEX study, CFD analyses and HVAC engineering explicitly aligned with each other.

Approach:
Prohead Engineering carried out an end-to-end project:

• ATEX zoning & EPD input
  Systematic risk assessment and zoning in accordance with NBN EN IEC 60079-10-1/-2; specification of detection and alarm levels and their interlocks with ventilation and electrical equipment.
• CFD analyses (H₂ accumulation)
  Simulation of representative leaks, ventilation configurations and stagnation zones. The results served as the design basis for air flow rates, the positioning of supply/extraction and the avoidance of dead zones.
• HVAC engineering driven by explosion safety
  Functional requirements (FRS HVAC), interlock and alarm lists, IO links with the process PLC. Fail-safe philosophy: automatic ramp-up of ventilation on detection trips, controlled shutdown of non-Ex equipment in hazardous areas, and guaranteed safe states on loss of power.
• Tender frameworks & execution
  Specification texts for hazardous and non-hazardous areas, cost estimates, tagging/asset lists and “design for tendering” to ensure unambiguous execution and later audits.

Result:

• Zoning plans with explanatory notes (EPD-ready).
• CFD notes with design scenarios and limit values.
• HVAC specifications (FRS, interlock/alarm lists, IO lists) and tender file.

The site now has an audit-ready ATEX file with a computationally substantiated ventilation and detection strategy, effectively preventing H₂ accumulation and making legal compliance demonstrable.