ISO 18195:2019

Overview

ISO 18195:2019 - Method for the justification of fire partitioning in water cooled nuclear power plants (NPP) - provides a structured, performance‑based methodology to verify the effectiveness of fire partitioning and fire barriers in water‑cooled nuclear plants. The standard links standardized fire resistance tests with room‑level fire modelling to determine a barrier’s global performance during realistic, extended‑duration fires, complementing the conventional ISO‑fire rating.

Key topics and technical requirements

• Design‑basis fire temperature curve (room fire curve): Guidelines for defining the thermal load inside a room (design basis fire) using numerical and empirical approaches.
• Performance curve / performance diagram: Methods to derive global barrier performance from a reference standard fire test and to plot temperature/response curves for extended durations.
• Test characterization and additional testing: Criteria to assess whether existing standardized tests suffice or whether further laboratory and ad‑hoc tests are required to demonstrate robustness.
• Numerical tools validation & verification (V&V): Requirements for using zone models or CFD tools, including validation, sensitivity and uncertainty treatment.
• Qualification of test laboratories: Expectations aligned with ISO/IEC 17025 competence for fire resistance laboratories performing characterization or additional tests.
• Limitations and applicability: Explicit discussion of where the method applies and its bounds; includes annex examples (fire spreading, scenario values, loss of classification).
• Structured workflow: A global approach and flowchart to guide practitioners through analysis, modelling, testing and acceptance steps.

Practical applications and users

Who uses ISO 18195:2019:

• Fire safety engineers and consultants performing performance‑based fire assessments in NPPs.
• Nuclear plant designers and project teams justifying compartmentation and passive fire protection.
• Nuclear safety authorities and regulators reviewing fire hazard demonstrations and safety cases.
• Fire resistance laboratories conducting standard and supplementary tests.

Typical uses:

• Justifying partitioning to prevent fire propagation between safety‑critical rooms.
• Demonstrating a barrier’s effectiveness for fires of extended duration beyond ISO‑fire classification.
• Integrating laboratory test data with validated room fire simulations for risk‑informed decisions.
• Supporting regulatory submissions and safety analyses for new builds, retrofits or design changes.

Related standards

• ISO 13943 (Fire safety - Vocabulary)
• ISO/IEC 17025 (Competence of testing and calibration laboratories)
• ISO 12749 series (Nuclear energy vocabulary)

Keywords: ISO 18195:2019, fire partitioning, nuclear power plant (NPP), fire barriers, design basis fire, performance curve, fire resistance testing, numerical V&V, fire safety engineering, ISO fire rating.