Overview
ISO 9404-1:1991 - "Enclosures for protection against ionizing radiation - Lead shielding units for 150 mm, 200 mm and 250 mm thick walls - Part 1: Chevron units of 150 mm and 200 mm thickness" specifies the properties, designation and modular dimensions of lead chevron units used to build shielded enclosures. The standard covers both basic units (bricks, posts) and functional units (aperture bricks, windows, sphere units, plugs and reducing units). Annex A is informative (bibliography).
Key topics and technical requirements
- Scope and classification
- Defines units for construction of radiation shielding walls and classifies them into Category 1 (standardized), Category 2 (special or regionally used) and Category 3 (transition/withdrawn).
- Unit designation
- A systematic reference number indicates lead thickness (3 = 150 mm, 4 = 200 mm), profile (V = chevrons), assembly direction and unit type.
- Materials and mechanical properties
- Units are made of an antimonial lead alloy (“lead shielding units”) with specified minimum density and Brinell hardness to ensure performance and durability.
- Chevron profile and modularity
- Detailed specifications for chevron angle, height and length, with two permitted assembly directions (chevron pointing right or left). The modular design generally follows a 100 mm × 100 mm module to permit staggered or straight joints.
- Unit types
- Standardized plain bricks, corner bricks, end bricks, special bricks (square and X bricks), posts, aperture bricks and window assemblies, sphere units, plugs and reducing units.
- Assembly and tolerances
- Guidance for assembly of basic and functional units, jointing strategies, and dimensional tolerances for reliable shielding performance.
- Windows and apertures
- Minimum glass density and thickness requirements for viewing windows are specified; aperture and window units include specific mounting and offset considerations.
Practical applications and users
- Who uses ISO 9404-1
- Radiation shielding designers, medical physicists, radiotherapy architects, nuclear facility engineers, manufacturers of lead shielding bricks, and regulatory or compliance teams.
- Where it applies
- Design and construction of shielded enclosures for diagnostic radiology, radiotherapy treatment rooms, nuclear medicine, isotope handling facilities, research laboratories and temporary shielding installations.
- Benefits
- Ensures modular, interchangeable shielding components, predictable attenuation performance, ease of assembly, decontamination-friendly finishes and compatibility across projects and suppliers.
Related standards
- ISO 7212 - standardization of 50 mm and 100 mm lead shielding units (complements ISO 9404 series)
- Prepared by ISO/TC 85 (Nuclear energy), SC 2 (Radiation protection)
Keywords: ISO 9404-1, lead shielding units, chevron bricks, ionizing radiation protection, radiation shielding design, aperture bricks, 150 mm walls, 200 mm walls.
Open preview (PDF)Enclosures for protection against ionizing radiation — Lead shielding units for 150 mm, 200 mm and 250 mm thick walls — Part 1: Chevron units of 150 mm and 200 mm thickness
