ISO 1709:2018

Overview

ISO 1709:2018 - "Nuclear energy - Fissile materials - Principles of criticality safety in storing, handling and processing" defines the fundamental principles and limitations for operations with fissile materials outside reactors. The standard provides guidance for nuclear criticality safety, focusing on equipment design, operating controls and the assessment of procedures and operations. It applies within the boundaries of nuclear establishments and can also be used for the transport of fissile materials. ISO 1709:2018 does not prescribe detailed quality-assurance requirements, administrative criteria (see ISO 14943), or radiation-health effects except where material properties affect criticality safety.

Key topics and technical requirements

ISO 1709:2018 addresses the following technical topics and requirements:

• Procedures and responsibilities

  • Clear assignment of operational responsibility for criticality safety.
  • Written procedures for operations above threshold quantities and visible availability in operating areas.
  • Review of procedures by personnel skilled in nuclear criticality safety, ideally administratively independent from operations.

• Equipment design and control

  • Incorporation of safety into equipment geometry and plant design to reduce criticality risk.
  • Equipment control and design restrictions to maintain subcritical configurations.

• Criticality assessment and demonstration of safety

  • Requirement for a nuclear criticality safety assessment for applicable operations, considering normal and credible abnormal conditions.
  • Use of established criteria and demonstration of an appropriate margin of criticality safety.

• Technical criteria and factors affecting criticality

  • Methods of control and achievement of control (defence-in-depth).
  • Factors: mass, geometry, volume, concentration, moderation, neutron absorbers, physical/chemical form, density, enrichment, reflection, interaction, temperature.
  • Consideration of possible abnormal conditions and processing violations.

• Operational controls and monitoring

  • Material control, dispatch/receipt procedures, training, monitoring of procedures.
  • Need for emergency planning and criticality detection/alarm systems where appropriate.

Practical applications

ISO 1709:2018 is used to:

• Develop and validate criticality safety assessments and operating limits.
• Inform design criteria for storage vessels, containers and processing equipment to avoid inadvertent criticality.
• Establish written operating procedures, training programs and monitoring controls.
• Support safety analyses for handling, processing and short-term transport of fissile materials.

Who should use this standard

• Nuclear criticality safety engineers and analysts
• Plant/process designers and equipment manufacturers
• Nuclear facility operators and operations management
• Regulatory bodies, safety auditors and compliance teams
• Transport planners handling fissile consignments outside reactor cores

Related standards

• ISO 7753 - criticality detection and alarm systems
• ISO 11320 - emergency preparedness and response for nuclear criticality safety
• ISO 14943 - administrative criteria for nuclear criticality safety

Keywords: ISO 1709:2018, nuclear criticality safety, fissile materials, criticality assessment, equipment design, storage, handling, processing, criticality alarm, transport.