INRAT-H
More study resources
Cheat sheet
Keep the key ideas within reach.
ExploreKey terms
Get comfortable with the vocabulary.
ExploreStudy plan
Give each week a clear focus.
ExploreCommon mistakes
Understand the traps and how to avoid them.
ExploreCase studies
Put your knowledge to work in context.
ExploreExam-day guide
Prepare for the day ahead.
ExploreAbout this exam
INRAT-H, also described as the Human Factors paper within the International Nuclear Reactor Operator License Examination family, is a professional knowledge assessment focused on how people actually perform inside a nuclear control room. It is aimed at licensed operators, senior reactor operators, shift supervisors, simulator instructors, human factors practitioners, and regulator or utility staff who review operating events and crew performance. The exam is not a plant-specific systems test. It asks you to reason about why competent people make errors, how interface design and procedures shape those errors, and how organizations detect and correct them before consequences emerge. Content spans eight domains: human performance fundamentals and error mechanisms; attention, perception, memory and decision making; human-system interface and control room design; procedures, human factors engineering and task analysis; fatigue, stress, workload and shift work; teamwork, communication and crew resource management; safety culture, human reliability and event investigation; and training, competence and licensing. Expect multiple-choice items plus scenario-based questions in which you diagnose a described situation and choose the most defensible action or causal explanation. Preparation works best in layers: build vocabulary and mental models from the domain list, then practise applying them to written event narratives, then explain your reasoning aloud as if briefing a crew. Confirm all administrative details with the official examining body.
What you'll study
About INRAT-H preparation
What is INRAT-H actually testing?
Applied human factors judgement in nuclear operations, not memorized plant data. Items ask you to recognize error-likely conditions, interpret crew behaviour, evaluate interface and procedure design, and select proportionate corrective actions. Many candidates find the concepts familiar but the application demanding.
What format should I expect on the day?
Multiple-choice questions and scenario-based items built around written descriptions of situations. No exhibits are needed to answer. The official examining body publishes the definitive format, item count and timing, so check its site rather than relying on secondhand reports.
How difficult is the exam?
Moderate to hard for most candidates. The facts are not obscure, but distractors are plausible and often describe a common but wrong remedy. People who have investigated real events or instructed in simulators usually find the scenario items more intuitive than those who have only read theory.
How long is the exam, and how many questions are there?
The official body publishes the current question count and time allowance, and these change between administrations. Confirm them on its website before you plan your pacing. Treat any number quoted in a forum or training advertisement as unverified.
What happens if I fail a section?
Retake rules, waiting periods and any sectional credit are set by the examining body and vary by administration. Consult its published candidate handbook for the binding policy. Do not assume partial credit carries forward.
In what order should I study the eight domains?
Start with human performance fundamentals and cognitive processes, since later domains reuse that vocabulary. Then take interfaces, procedures and task analysis together as a design block. Finish with fatigue, teamwork, safety culture and training, which are easiest to reason about once the earlier models are solid.
What are the most common ways candidates lose marks?
Choosing the action that feels decisive rather than the one that addresses root cause; confusing individual error with systemic weakness; ignoring workload, fatigue and communication as contributing factors; and failing to read scenario stems carefully enough to notice which role you are being asked to play.
How should I practise scenario items?
Write short incident narratives from public event reports, then for each one state the error mechanism, the performance-shaping factors, the weakest barrier and one corrective action. Compare your reasoning with a colleague. Explaining your choice aloud exposes gaps that rereading notes does not.
Do I need plant-specific knowledge?
No. The exam is generic across reactor types and does not test setpoints, valve lineups or system diagrams. What transfers is your understanding of human performance, crew dynamics and organizational safety, which is why operators from different plants can prepare from the same material.
Where do I find fees, dates and eligibility?
Only from the official examining body. It publishes current fees, application windows, eligibility requirements and results policy on its website. This page is independent study material and is not affiliated with, endorsed by, or speaking for that organization.