ML19011A445
| ML19011A445 | |
| Person / Time | |
|---|---|
| Issue date: | 01/16/2019 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| Nathan Siu 415-0744 | |
| Shared Package | |
| ML19011A416 | List:
|
| References | |
| Download: ML19011A445 (10) | |
Text
Summary and Closing Remarks Lecture 10-1 1
Key Topics
- Course overview
- Closing comments 2
Course Objectives and Approach
- Learning Objectives:
- Knowledge of basic probabilistic risk assessment (PRA) and risk-informed decision making (RIDM) concepts and the use environment;
- Exposure to and limited practice with nuclear power plant (NPP) PRA: modeling approaches, elements, and mechanics; and critical thinking
- Awareness of PRA/RIDM history, recent developments and controversies, and future challenges
- Delivery via lectures (with some knowledge checks and thought exercises), workshops, discussion 3
Schedule 4
Wednesday 1/16 Thursday 1/17 Friday 1/18 Tuesday 1/22 Wednesday 1/23 Module 1: Introduction 3: Characterizing Uncertainty 5: Basic Events 7: Learning from Operational Events 9: The PRA Frontier 9:00-9:45 L1-1: What is RIDM?
L3-1: Probabilistic modeling for NPP PRA L5-1: Evidence and estimation L7-1: Retrospective PRA L9-1: Challenges for NPP PRA 9:45-10:00 Break Break Break Break Break 10:00-11:00 L1-2: RIDM in the nuclear industry L3-2: Uncertainty and uncertainties L5-2: Human Reliability Analysis (HRA)
L7-2: Notable events and lessons for PRA L9-2: Improved PRA using existing technology 11:00-12:00 W1: Risk-informed thinking W2: Characterizing uncertainties W4: Bayesian estimation W6: Retrospective Analysis L9-3: The frontier: grand challenges and advanced methods 12:00-1:30 Lunch Lunch Lunch Lunch Lunch Module 2: PRA Overview 4: Accident Sequence Modeling 6: Special Technical Topics 8: Applications and Challenges 10: Recap 1:30-2:15 L2-1: NPP PRA and RIDM:
early history L4-1: Initiating events L6-1: Dependent failures L8-1: Risk-informed regulatory applications L10-1: Summary and closing remarks L8-2: PRA and RIDM infrastructure 2:15-2:30 Break Break Break Break 2:30-3:30 L2-2: NPP PRA models and results L4-2: Modeling plant and system response L6-2: Spatial hazards and dependencies L8-3: Risk-informed fire protection Discussion: course feedback 3:30-4:30 L2-3: PRA and RIDM:
point-counterpoint W3: Plant systems modeling L6-3: Other operational modes L8-4: Risk communication Open Discussion L6-4: Level 2/3 PRA:
beyond core damage 4:30-4:45 Break Break Break Break 4:45-5:30 Open Discussion W3: Plant systems modeling (cont.)
W5: External Hazards modeling Open Discussion 5:30-6:00 Open Discussion Open Discussion
On Risk-Informed Decision Making (RIDM) and Probabilistic Risk Assessment (PRA)
Risk has qualitative and quantitative elements What can go wrong Consequences Likelihood RIDM considers risk as an important but not sole factor PRA provides a formal, probabilistic view on risk PRA has identified potential vulnerabilities and supported improvements Plant design and operations Process efficiencies PRA has weaknesses as well as strengths; skeptics have valid concerns Critical PRA elements Search for failures - not a cookbook Fully characterize uncertainties 5
On PRA - The Technical Process The math (probability and statistics) is important, but not the be-all/end-all. System understanding (engineering, science) is critical for realism, communication, and confidence:
- How do things work?
- How can things fail?
Details matter: need plant-specific information (e.g., from walkdowns) and understanding of operational experience PRA models are complex, but complexity has evolved from problem needs
- System scope, technical disciplines
- Rare events, sparse data
- Importance of dependencies (aleatory - functional, shared equipment, environmental, human-caused, etc. - and epistemic) 6
On PRA - The Social Side Modeling is a subjective enterprise
- Analysts need to make choices, need to take ownership of choices.
- Documentation and external review are critical Multiple technical disciplines are involved
- Different viewpoints on importance of scenario features, appropriate methods for analysis; need to avoid polarization
- Results are heterogeneous; degree varies with topic Risk communication is challenging
- Interchange rather than education
- Comparisons with safety goals often dont work
- Trust is critical 7
On PRA Technical Improvements
- Developers, analysts, and users have different perspectives on needed improvements
- Extracting more from past work (vs. focusing on weaknesses, inapplicability)
- Considering new approaches (why not vs. why)
- Need to
- Avoid force fitting (If all you have is a hammer)
- Recognize implementation costs, fundamental value-added question 8
Final Remarks RIDM is a sensible approach to safety-related decision making
- Accounts for risk as we understand it
- Includes backstops for limitations in technology, knowledge PRA (the product) is a tool
- Can be well-used or misused
- Not easy to understand; complexity is driven by problem needs PRA (the process) is a human enterprise
- Human strengths and weaknesses
- Integrates disciplines, supports learning
- Searches for failures but is an expression of optimism: we understand enough, can make improvements 9
A Final RIDM Question 10 How many in the car?