Post on 30-Mar-2018
CHERNE intensive course:Probabilistic Risk Assessment (PRA)
for PWR nuclear power plantMartorell S.1, Keshav C.2
1 Universitat Politècnica de València (SPAIN)2 Haute Ecole Spaak, rue Royale 150, B-1000 Brussels,
Belgium
Background
Objective?Give an introduction of the fundamentals and procedures of a probabilistic risk assessment and develop a practical case for a PWR nuclear power plant.
Advantages?• PRA is a systematic and comprehensive methodology
to evaluate risks associated with every life-cycle aspectof a complex engineered technological entity, fromconcept definition, through design, construction andoperation, and up to removal from service
• PRA has become a standard tool that helps risk informed decision making
Content & Logistic
1. Development of the course- Introduction to fundamentals and procedures - Lessons
- Practical application – Computers room
2. Introduction to fundamentals and procedures to develop a PRA
- Introduction to LWR technology (Elements, PWR, BWR)
- Overview of the PRA
- Accident identification
- Accident sequence modeling
- Data assessment
- Accident sequence quantification
Content & Logistic
1. Practical application to a PWR Nuclear Power Plant-Large Break Loss of Coolant Accident (LBLOCA) – Level 1 PRA
-Use of Software tools
2. Application tools-Level 1 PRA - LBLOCA documentation
-FaultTree+ , IAEA Database,…
3. Evaluation of the course-Case Study (portfolio)
4. ReferenceProcedures for conducting PSA of NPP (Level 1). Safety Series Nº 50-
P-4. International Atomic Energy Agency. Vienna. 1992.
Overview
24h IC given in January 2011 at UPV for the first time and attended by students from Brussels and Jülich.
Introduction to fundamentals and procedures to develop a PRA
PRA: Risk Concept
SAFETY PRINCIPLES AND SYSTEMS
HAZARD RISKACCIDENT SEQUENCES
Reliability, Maintainability,
Availability (RAM) of
Safety Related Equipment (SRE)
INITIATING
EVENTHAZARD
INTERMEDIATE EVENTS
CONSE-
QUENCE
FREQUENCY
DAMAGE
(SEVERITY)
CAUSES
(FAILURES,
ERRORS, …)
RISK
SAFETY
PREVENTION
PROTECTION
DECISION
MAKING
PRA: 3 levels!
In international practice three levels of PRA evolved
Level 1:
The assessment of plant failures leading to the determination of core damage frequency
Level 2:
The assessment of containment response leading, together with Level 1 results, to the determination of containment release frequencies
Level 3:
The assessment of off-site consequences leading, together with the results of Level 2 analysis, to estimate public risks
PRA: Steps & tasks
Management and
organization
1
Identification of hazards& accidentinitiators
Accidentsequencemodeling
3
Data assessment
4
Accident
sequence
quantification
5
Reportof the
analysis
6
Procedures for conducting PRA of NPP (Level 1). Safety Series Nº 50-P-4. International Atomic Energy Agency. Vienna. 1992.
2
Practical application to a PWR Nuclear Power Plant:
LBLOCA
Introduction
1. PWR Nuclear Power Plant
LBLOCA – PRA level 1
2. Analysing ToolsFaultTree+
IAEA Database
3. Steps
Accident sequence modelling
Data assessment
Accident sequence quantification
Identification of hazards & Accident initiator
1. Familiarization with the plant
2. Identification of hazards (sources of radioactive release)
3. Selection of plant operational states
4. Definition of consequences and damage states
5. Identification of accident initiators
6. Determination of safety functions and plant systems
Identification of hazards & Accident initiator
1. Familiarization with the plant
2. Identification of hazards (sources of radioactive release)
3. Selection of plant operational states
4. Definition of consequences and damage states
5. Identification of accident initiators
6. Determination of safety functions and plant systems
CONSEQUENCE:
Core damage
HAZARD:
Core as the onlysource of radioactive
release
Event Sequence Modelingusing FaultTree+ (Reliability Workbench)
GIATOP
FALLO DE LA INYECCION
DE DOS O MAS
ACUMULADORES
GIA4
DESCARGA INEFICAZ DEL
ACUMULADOR 15T01A
GMIA001
MODULO FALLOS
BASICOS DE VALVULAS
DE DESCARGA DEL
ACUMULADOR 15T01A
GIA5
DESCARGA INEFICAZ DEL
ACUMULADOR 15T01B
GMIA002
MODULO FALLOS
BASICOS DE VALVULAS
DESCARGA DE
ACUMULADOR 15T01B
GIA6
DESCARGA INEFICAZ DEL
ACUMULADOR 15T01C
GMIA003
MODULO FALLOS
BASICOS DE VALVULAS
DE DESCARGA DE
ACUMULADOR 15T01C
CASA-XR1
INOPERABILIDAD DEL
ACUMULADOR
GIA7
LOCA GRANDE O LOCA
INTERMEDIO NO INDUCIDO
POR ATWS
1TU10LRF1B
LOCA EN RAMA FRIA DEL
LAZO 1 DEL PRIMARIO
GIA7
LOCA GRANDE O LOCA
INTERMEDIO NO INDUCIDO
POR ATWS
1TU10LRF2B
LOCA EN RAMA FRIA DEL
LAZO 2 DEL PRIMARIO
GIA7
LOCA GRANDE O LOCA
INTERMEDIO NO INDUCIDO
POR ATWS
1TU10LRF3B
LOCA EN RAMA FRIA DEL
LAZO 3 DEL PRIMARIO
GIA1
FALLO DE LA INYECCION
DEL ACUMULADOR
15T01A
GIA2
FALLO DE LA INYECCION
DEL ACUMULADOR
15T01B
GIA3
FALLO DE LA INYECCION
DEL ACUMULADOR
15T01C
GIA8
PRESION INSUFICIENTE EN
ACUMULADORES POR
ERRORES DE
CALIBRACION
GIAO
FALLOS INDEPENDIENTES
DE ACUMULADORES
>_ 2
Data Assessment
• Assessment of the frequency of initiating events
• Assessment of RAM of components
• Databases
• Assessment of human error probabilities
Accident sequence quantification
• Qualitative analysis (Boolean equations)
• Quantitative analysis of frequencies of accident sequences
• Importance and sensitivity analysis
• Uncertainty analysis
Overview by students
• Very interesting (new or complementary, used for thesis, apply the software to any technical risk analysis : Japan!)
• Theory vs. Practical? “Good distribution between both”, “theory well detailed and organized for short time”, “practical case help to understand some of the theoretical aspects”
• Improvements? Maybe make the course longer
• Recommended? Yes by all the students! It was a good experience…
Thank you for your attention