Swiss Federal Nuclear Safety Inspectorate

Integrated OversightAn Approach to Systematic Supervision of NPP Safety

Dr Peter Flury

31 May 2006

2 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

Integrated OversightSystematic Supervision of Nuclear Safety

What is Nuclear Safety?

3 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

Nuclear SafetyIAEA-Definitions

general nuclear safety objective

INSAG-12

radiation protection objective

technical safety

objective

Safety Objectives 1. safety• nuclear safety• radiation safety• safety of radioactive

waste management• safety in the transport

of radioactive material2. non-radiological aspects of

safety

Draft Safety Guide DS298

4 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

Nuclear SafetySwiss Definition

nuclear safety = protection of man and environmentfrom radiation hazards due to

reactor operationfuel handlingfuel storageradioactive waste processingradioactive waste storagetransport of radioactive material

by technical and organisational means

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Structuring information on nuclear safetyBasic assumption

definition ofprecautions

implementation ofprecautions

nuclearsafety

6 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

Structuring information on nuclear safetyBasic assumption

Requirements vs. Operational Experience

nominal situation defined in documents

actual situation observed in the plant

7 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

Structuring information on nuclear safetyAdditional assumption

technicalfactors

humanfactors

organisationalfactors

nuclearsafety

8 CNRA Workshop 2006-05-31 | Integrated Oversight (Dr Peter Flury, Swiss Federal Nuclear Safety Inspectorate)

nominal situation defined in documents actual situation observed in the plant

Structuring information on nuclear safety

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Perspectives

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Defence in Depth Perspective

e.g. safety culture, plant risk

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Safety Goal Perspective

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• 1 scale for all situations from normal operation to major accidents

• Basis: International Nuclear Event Scale (INES)• Extension: Below Scale and Normal Operation

Integrated OversightThe scale for assessing nuclear safety

Integrated OversightInspection Results

Every inspection result is assigned to the structure of the nuclear safety assessment system.

Integrated OversightReportable EventsThe contributing factors and effects of reportable events are assigned to the structure of the nuclear safety assessment system.

1 event = several rated aspects

A

A V

V

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Integrated OversightAdditional data (planned)

plant modification proposals

periodically reported operational experience (results of periodic testing and checking of systems and components, safety indicators)

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Safety Assessment ResultsGoals of Analysis

strengths

weaknesses

Safety AssessmentResultsFictitious Example

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