IAEA’s Simulation-Type Training on Probabilistic Safety … · 2013-05-02 · The paper provides...

Nordic PSA Conference – Castle Meeting-2013, 10-12 April 2013, Stockholm, Sweden

1 ‘IAEA Simulation-Type Training on PSA’ by A.Lyubarskiy, I.Kuzmina, P.Hughes, P.Hughes, P.Wells, M.Mellinger-Deroy, O.Andrianova

IAEA’s Simulation-Type Training on Probabilistic Safety Assessment:

Recognizing the Current Needs and Providing Solutions

A.Lyubarskiy,1 I.Kuzmina,

1 P.Hughes,

1 P.Wells,

1 M.Mellinger-Deroy

1

O.Andrianova2

1IAEA, Vienna International Center, PO Box 100, 1400 Vienna, Austria, [email protected]

2The Open University, PO Box 197, Milton Keynes, MK7 6BJ, United Kingdom,

[email protected]

Abstract

The vast majority of Level-1 Probabilistic Safety Assessment (PSA) studies for operating Nuclear Power

Plants (NPPs) were completed within the last twenty years. The experience shows that PSA projects for

NPPs represent major commitments in terms of resources and time. Many PSA specialists developed their

skills and knowledge through the performance of practical work on PSA modeling within those PSA

projects. Practical experience in PSA performance is deemed to be very important for building an in-depth

understanding of PSA results and insights that are necessary prerequisites for consistent use of PSA, by

both the utility and the nuclear safety regulatory body. However, currently there are few opportunities for

inexperienced engineers to receive on-the-job training and thereby develop their PSA modeling

competence. To address this challenge, the International Atomic Energy Agency (IAEA) has developed,

through an extra-budgetary project funded by Norway aimed at building competence and capacity for safety

assessment in countries embarking on nuclear power programmes, and successfully implemented a special

PSA practical training program as a means of compensating for the lack of hands on opportunities to build competence in PSA through performance of real PSA studies. The training includes lecturing on PSA

methodologies, followed by practical training in performance of a PSA for a simplified NPP design using

commercial PSA software. The developed model enables training in PSA concepts, such as minimal cut-

sets, importance measures, etc. As a result of this simulation-type training, the trainees obtain not only

basic knowledge in PSA techniques as well as practical skills with the PSA software, but also a feeling of

confidence that the development of a PSA is a manageable task and that the PSA represents a valuable

safety analysis tool. The simulation-type training has been successfully conducted by the IAEA in training

for three countries introducing nuclear power programmes, and the effectiveness of this training has been

clearly demonstrated. The paper provides details of the training approach and discusses some relevant

organizational issues to be noted, as well as outputs and outcomes.

1. INTRODUCTION

It is known that PSA projects for NPPs represent major commitments in terms of resources, time, and specific expertise. Many risk assessment specialists, to a large extent, developed their skills and knowledge

through performance of practical work on PSA modelling within the PSA projects completed in the last

twenty years. Practical experience in PSA performance is deemed to be very important for building an in-depth understanding of the PSA results and insights that are necessary perquisites for consistent use of PSA

in the decision making process. This is true for both utilities and for nuclear safety regulatory organizations.

However, there are fewer opportunities for young engineers to receive on-the-job training on PSA when the

studies have been already completed, and this represents a challenge. Obviously, special projects are needed to compensate for the lack of opportunities to build competence for PSA through performance of real PSA

studies. This is particularly important for specialists from countries introducing and considering the

introduction of nuclear power programmes, with limited or no experience in safety assessment techniques and limited knowledge in nuclear power technology. There are some examples of this type of training, for

example the SOARCA project [5] in the USA, but these are relatively rare.

Responding to the challenge, the Safety Assessment Section of the Division of Nuclear Installation Safety, Department of Nuclear Safety and Security (SAS/NSNI/NSS) of the IAEA, through an extra-budgetary

project (EBP) funded by Norway aimed at building competence and capacity for safety assessment in



countries embarking on nuclear power programmes, has developed and implemented a special Level-1 PSA

practical training programme. The programme is aimed at compensating for the lack of opportunities for on-the job PSA training. The PSA training programme is part of a larger safety assessment training project

being conducted by SAS/NSNI/NSS.

2. SELECTION OF TRAINING METHODS

2.1 Types of Training Methods

The goal of any training is to build effective competence of the trainees in a certain area in the most

efficient manner, minimizing resources and time spent. Efficiency can be achieved by selection and

application of the most appropriate and effective training methods.

Two major types of training methods, which are different in terms of the training delivery approach and the

means of interactions between trainers and trainees, are known:

(1) Conventional training that focuses on transferring knowledge through one-way communication, i.e. in the form of lectures and presentations, and

(2) Experimental training, where the trainer engages the trainees to participate in the learning process

by simulating real-life situations and asking trainees to solve problems.

According to many authors, the conventional training method is not particularly effective in adult learning

[6]. Many researchers indicate that active participation of trainees is an important factor in increasing the effectiveness of the learning process. This is due to the fact that up to approximately 90% of information

can be memorized during a hands-on training session and only about 20% through reading and hearing

during a lecture [7]. The majority of authors agree that “learning by doing” or learning based on experience

(so called “experimental training” or “simulation-type training”) provides a higher level of knowledge transfer.

In addition to the delivery methods, training approaches can also be categorized according to the training subject complexity as follows [8]:

(1) General training aimed at teaching trainees on general, non-technical areas (e.g. communication or

managerial skills development), and

(2) Specific training aimed at teaching trainees in a specific area of knowledge.

Considering possible combinations of the training delivery methods and the complexity of the subject, the

effectiveness in terms of memorizing the information delivered during the training can be evaluated in increasing order according to the following [7],[8]:

General conventional training (≤ 20% effectiveness)

Specific conventional training (20% - 50% effectiveness) General experimental training (40% -60 % effectiveness)

Specific experimental training (≥ 60% effectiveness)

2.2 Overview of the Simulation-Type Training Approach

The simulation-type training method belongs to the category of “specific experiential training” when the

trainees are learning by doing, focusing on specific tasks and accumulating lessons learned from everyday activities [9],[10]. The aim of the simulation-type training is to educate trainees and enhance their

knowledge in a specialized area in an encouraging and memorable way. The teams of trainees, coached by

trainers, work on specific problems similar to the actual tasks in real life and conditions that can be encountered in their actual job [11]. This method allows the trainees to experience practical aspects and

explore the simulated problem in a hands-on way, facing errors and finding solutions. Therefore, especially

for newcomers, this training is seen as the most effective one.



The common approach of simulation-type training on a complex task is that trainees work on specified sub-

tasks in several sub-groups during several sessions. During each session, after the introduction by trainers, solutions are obtained for parts of the problem (sub-tasks) by trainees working in sub-groups, then the

solutions are presented by the trainees, discussed with the whole audience and checked by trainers; then,

after adjustments to the work completed, if needed, the next sub-tasks are specified until all constituent

parts of the complex problem are covered [10]. Generally, the simulation-type training includes three iterative steps as follows:

(1) Briefing and Preparation

(2) Simulation Activity (3) Debriefing and Discussion.

The overall training process involving these three steps is illustrated in Fig.1.

Fig. 1 The Process of Simulation-type Training

The benefits of the simulation-type training are the following:

- Thorough understanding of the contents of the sub-tasks; - Building self-confidence of trainees’ capability to apply the knowledge obtained;

- Understanding interconnections between different sub-tasks;

- Understanding specific features of team-work on the complex training task.

Using simulation-type training, complex tasks can be taught in a timely manner, at the same time allowing

trainees to effectively accumulate new knowledge [7].

The simulation-type training is the most intensive type of experiential learning and requires careful

planning, material preparation and appropriate tools (equipment, software). The major part of preparatory

work requires development of scenarios close to “real life” cases that are integrated into the simulation case, and solutions for those scenarios.

It is important to note that the success of simulation-type training depends to a large extent on the personality of trainers, whose task is to encourage participants and ensure that the simulation is conducted

smoothly and effectively. This type of training requires high involvement of trainers throughout all training

sessions. The trainers have the multiple roles of lecturers, advisors, supervisors, approvers, and facilitators.

These roles are dynamically changing throughout the training sessions. It is important for the success of simulation-type training that trainers possess good technical expertise and are also able to conduct training

in an encouraging manner, displaying good facilitator skills.

Currently, simulation-type training in the PSA area is not widely employed, though it is provided by some

companies specializing in the area of NPP safety assessment [11].

(1) Briefing and

Preparation

(2) Simulation

Activity

(3) Debriefing and

Discussion

Continue with the next sub-task



2.3 The Selected PSA Training Approach

The training programme for Level-1 PSA developed by SAS/NSNI/NSS combines the conventional

training approach for theoretical knowledge, and the simulation-type training approach for practical skills

development. The concept is illustrated in Fig.2.

The developed training programme has been used by SAS/NSNI/NSS to train teams from newcomer

country nuclear safety organizations for PSA technology to build competence in assessing the safety of

NPPs. The training was conducted under the umbrella of an IAEA extra budgetary programme funded by Norway. The countries participating in the programme are Vietnam, Malaysia, and Jordan. The details of

this programme are discussed below.

Fig. 2 General Structure of the IAEA Level-1 PSA Training Programme

3. OVERVIEW OF LEVEL-1 PSA TRAINING ORGANIZATION

3.1 Objectives and Outputs of Level-1 PSA Training Programme

The Level-1 PSA training programme has several specific objectives:

• The primary objective is to provide trainees with theoretical knowledge about the PSA technique.

• The second objective is to teach trainees on how the knowledge of NPPs design and operation can

be translated into logical models needed to assess risks associated with NPPs.

• The third objective is to show trainees how their understanding of the key safety principles (e.g.

Defence-in-Depth, safety functions, safety margins, etc.) can be enriched when insights from a risk

assessment study, and in particular from Level-1 PSA, are available.

The outcome of the training programme is a set of specific competencies, knowledge and skills regarding

the understanding of Level-1 PSA as follows:

• Understanding the scope, objectives, and theoretical basis of PSA;

• Understanding of the process of Level-1 PSA model development and what information is needed

for the performance of Level-1 PSA;

• Obtaining practical experience in the development of all Level-1 PSA technical tasks, including

integration of different tasks in the complex PSA model using PSA software;

• Becoming familiar with Level-1 PSA software;

• Understanding the PSA results and insights as well as the level of uncertainty associated with PSA

results;

• Understanding advantages and limitations of Level-1 PSA.



3.2 Target Audience and Specific Training Features

Generally, the target audience for the PSA training programme are specialists from design organizations,

NPPs and regulatory authorities not familiar or having limited knowledge about the PSA technique. The

training programme is developed in the way that it can be adjusted to account for the actual level of

experience of trainees and their knowledge of plant designs and operation.

The following three typical situations are considered:

(1) When inexperienced engineers are involved in the training activity with limited knowledge of NPP design and operation, the training programme includes the elements aimed at providing more details of

the safety principles of the design and operation of NPPs including systems important to safety, both

frontline and support systems. In addition, more information on the plant response to different initiating events is provided.

(2) When specialists familiar with the design and operation of NPPs constitute the majority of the audience,

more attention is given to the specific aspects of Level-1 PSA and more time is dedicated to exercises

and practical work with the PSA modelling software. (3) Finally, when the audience represents a mixture of experienced nuclear specialists and inexperienced

engineers, the programme is adjusted taking into account specific skills of the trainees’ group. In

particular, less information related to the design and operation of NPP may be given than in the first case, and more time could be dedicated to the practical modelling work with the PSA software. This

approach is supported by the idea that experienced specialists during the practical modelling work share

their knowledge on NPP design with inexperienced engineers and at the same time the inexperienced engineers facilitate the work with PSA software that is often easier for them.

It should be noted that the third situation is less preferable due to less predictable efficiency of the training.

For the first case, more time for the training may be needed to teach general NPP design and operational principles.

Regarding the specific trainers’ knowledge, for the first case, good knowledge not only in PSA, but also in plant design and operation, as well as in deterministic analyses are required. Ideally, the PSA training

should be preceded by a more general training on NPP design and safety assessment.

3.3 General Structure of the Training Programme

The training programme typically includes several sessions starting with theoretical training and followed

by practical training aimed as simulation of performance of a PSA for a simplified NPP design using PSA software. Two weeks usually are spent for the first PSA training: one week for theoretical training, and one

week for the practical part.

It is important to emphasize that such training structure is quite flexible and allows conducting several

subsequent practical training sessions increasing the level of complexity of different PSA modelling tasks,

e.g. adding more event trees and system models to the PSA model developed at the previous training.

For the theoretical training, class room lectures and interactive exercises, which require 15-30 minutes, are

conducted. The theoretical part of the PSA training is designed following the IAEA Safety Guide on Level-

1 PSA [13] and covers the main PSA tasks (Initiating Events Analysis, Accident Sequence Modelling, Human Reliability Analysis, etc.). The interactive exercises can be conducted either individually or in small

groups. Training volunteers (typically one to two volunteers) are invited to display their solutions; these are

followed by discussions moderated by the trainers.

For the practical training, the trainees are split into several fixed groups and guided by the trainers to

develop pieces of the PSA model, which then are integrated with the results of other groups and provide a

simplified but ‘working’ PSA model. Information on the design and operational features of the simplified NPP are provided as part of the practical training. When inexperienced engineers not familiar with NPP



designs constitute the majority of trainees, additional lectures on the typical plant designs and plant

operational features in normal and emergency conditions are also provided.

At the end of the training, a formal evaluation of the training is performed using specially developed

evaluation forms. These evaluations are utilized by the trainers as part of the continuous education,

feedback/lessons learned to benefit follow-on training.

3.4 Organizational Aspects of the Practical PSA Training

As stated above, the practical simulation-type PSA training is conducted following the theoretical training.

Before starting the practical training, the PSA software needs to be uploaded on the computers in the class

room. The training programme is organized in such a way that the trainees act as a PSA team developing a PSA for a real, but simplified NPP, using PSA software. The training is performed in one or several

training sessions depending on the needs of the trainees and available resources:

• If the trainees are not expected to be further engaged in the development of a PSA, only one

practical training session (one week) is organized that covers only basic Level-1 internal initiating

events, PSA techniques and tasks, and only a few event trees and safety system models.

• If the trainees are expected to be deeply involved in PSA activities, several training sessions will be

organized; they cover specific details on all PSA tasks, modelling additional front line and support

systems, and more event trees. The scenarios considered may also include internal and external

hazards modelling. This has been successfully done in training Malaysian and Vietnamese teams. Based on the experience, the number of sessions can be effectively increased up to three.

In all cases the design of the simplified NPP and description of the simplified systems performing main safety functions are provided to the trainees. The trainees are divided into working groups and each group

is responsible for the development of a piece of the PSA model in accordance with the modelling tasks

specified for each group. The groups work independently, but in close cooperation with each other and with

the trainers. Each trainer controls the work of an assigned group.

After each working groups completes the assigned tasks, the results (e.g. an event tree or a fault tree

developed) are presented by the leader of the group, reviewed by all of the groups and the trainers, and feedback is provided by the trainers. Then, after adjustments (if needed), the pieces of the PSA models are

integrated into a final model. It advisable that the integration is demonstrated by the trainers after they

check that the individual pieces are correct and the model indeed can be integrated (such checks can be

done in the evening, and the integration is demonstrated in the morning of the next day).

Following this, each group is assigned the task of performing different sensitivity studies utilizing the same

integrated model, and assessing the results achieved. The discussions are moderated by the trainers.

In the case when only one practical training session is envisioned, the activity ends with the PSA report

produced by the individual working groups merged into a combined report. In the case when more than one session is planned, all groups receive homework on PSA modelling to be accomplished prior to the next

practical training session. The following session starts with the review of the accomplished homework and

continues with new tasks.

Based on the experience of previous training sessions conducted, the following organisational aspects are

satisfied in order to maximize the training results:

• Trainees are split into equal-sized groups. All groups have approximately similar cumulative

background experience and knowledge. It is recommended that the number of trainees in each group should not be more than 5 and the number of groups should not be more than 4 (the optimum

number of trainees is 12-16 split into four equal groups).

• The number of trainers is equal to the number of groups.



• All training materials are developed in advance and distributed amongst the groups. The materials

of the theoretical training are available at least electronically, and the materials of the practical

training are available both electronically and in hard copies.

• Each group has at least one computer with the PSA software installed. It is preferable to have one

additional computer per group for working on PSA documentation. At least one scanner and printer

and one overhead projector and flipchart are available for all groups.

• The size of the room is sufficient to separate groups by distance, but still allow effective

communication, and viewing of the lectures and other projected materials. The optimum size of the

room: (2.5-3.0) m2 per one participant (including trainers).

• If the practical part of the PSA training is organized sometime after the theoretical part (i.e. not as

sequential two weeks), the same trainees participate in all training sessions.

• In order to provide continuity in the training process, some of the experts involved in the delivery

of the theoretical training are also involved in the delivery of the practical training process.

• If several practical training sessions are envisaged, the same team of experts is involved to ensure

continuity.

The training delivery process has the following specific features:

• The agenda of the training is a ‘living’ document, adjusted during the training sessions depending on

the feedback provided by the trainees

• Additional explanations of the tasks to be performed and demonstration of the software features are

provided to the trainees prior to each particular task

• Coaching in small groups: each group has a designated expert acting as a coach/trainer

• The trainers (the IAEA staff and invited experts) are prepared to check/integrate in real time and

after business time models developed by the trainees.

The trainers:

• Facilitate active participation of the trainees in the modeling work in an interactive manner

• Provide clear guidance what has to be achieved at each step of the training

• Provide clarification for particular issues not being well understood by the trainees during the

theoretical part of the training.

4. OVERVIEW OF THE TECHNICAL CONTENTS OF THE LEVEL-1 PSA TRAINING

PROGRAMME

4.1 Theoretical Training

The following core and optional modules have been developed for the theoretical part of the PSA training

programme:

Core modules

• Basics of probabilistic theory;

• Risk definitions and risk concept, safety goals, probabilistic risk criteria;

• Overview of the PSA scope and levels;

• Main tasks of Level-1 PSA for internal initiating events at full-power operation according to major

PSA elements represented in the IAEA Safety Guide on Level-1 PSA [13] (illustrated in Fig. 3);

• Main tasks of internal and external hazards PSA;

• Main tasks of low power and shutdown PSA.

Optional modules

• Overview of the main safety principles (the Defence-in-Depth safety concept, single failure

criterion, key safety functions, safety margins, etc.)



• Overview of major designs of NPPs; systems, structures and components (SSCs) involved in the

performance of safety functions; system dependencies; front-line and support systems

• Overview of deterministic safety assessment and deterministic analysis required to support Level-1

PSA.

The optional modules are included when the trainees have limited knowledge in NPP design and

operation (Target Group #1 in Section 3.2) and there is no possibility to provide them with a specialized

focused training on NPP design and operation prior to the training on PSA. The optional modules are to be delivered prior to the core modules or right after the basic risk concept.

Lectures are complemented by a number of interactive exercises and demonstrations that help trainees to keep their attention and better understand and perceive theoretical information. This complementary

element has features of experimental training (see Section 2.1).

Fig. 3 Main PSA Tasks

4.2 Practical Training

The essence of the Level-1 PSA practical training is that it allows the trainees to learn Level-1 PSA

techniques by performing specific PSA tasks. The key feature of the practical part of the training is that the trainees are deeply engaged in the performance of each Level-1 PSA task that is required for the

development of a real PSA model for a simplified NPP design. The ultimate goal of this part of the training

is to build practical skills and knowledge on how to perform a PSA for a NPP using dedicated PSA software.

It is important to emphasize that the training is not focused on teaching specific features of the PSA

software and only manipulating the software options; the training provides the opportunity to master the software features during performance of real modelling tasks. All PSA tasks (accident sequences, fault

trees, Boolean logic, initiating events, component reliability parameters, CCF, HRA, etc.) are taught

through the development of event and fault trees.

The training is performed such that the scope of the practical training is tailored to match the theoretical

training previously provided (e.g. theoretical training on Level-1 internal initiating events at-power PSA and practical sessions on developing respective Level-1 PSA models).

The Level-1 PSA practical training covers all PSA tasks described in the IAEA safety standards on Level-1

PSA [13] as it is shown in Fig. 3. The specific technical contents of the practical part of the Level-1 PSA



training programme is designed in such a way that it provides gradual increasing in the level of complexity

in PSA modelling tasks.

Description of the facility to be modelled and information to be provided

For training purposes, the simplified (not-real) NPP considered:

• Vessel-type, pressurized light water cooled, light water moderated reactor (PWR);

• Several typical safety systems.

For the one-week Level-1 PSA practical training, only four systems are considered for the detailed

modelling: Low Pressure Core Injection System (LPCI), Spray System (SS), Hydroaccumulators System (HA) and Power Supply System. Systems drawings, system design and operational features are provided to

the trainees. Other systems involved in safety functions performance are also briefly described: Main

Feedwater System (MFW), Emergency Feedwater System, High Pressure Injection System (HPSI), Service Water System, Secondary and Primary Side Depressurization Systems. These systems are not expected to

be modelled at the first session, but their functions are included in accident sequence models and modelled

as super-components1.

Trainees are also provided with the results of thermal hydraulic analyses for several initiating events in

order to define success criteria for the systems being modelled.

Finally information on the reliability data collection in the form of raw data for major components is given

to the trainees to allow performance of data analysis task.

Specification of modelling tasks

An example of the distribution of the tasks for the first practical training session between working groups is

shown in Table 1. This training session is designed for five working days.

Table 1 PSA Modelling Tasks

WG # Event Tree Model Fault Tree Model Other PSA Tasks

1 Medium Loss-of-Coolant

Accident (LOCA)

Low Pressure Core

Injections System

Limited to the modeling scope of the

working group:

- Reliability data analysis - Human reliability analyses (only

identification of human errors to be

modeled)

2 Small LOCA Hydroaccumulators

3 Loss of Offsite Power Power Supply System

4 General Transient Spray System

Each working group is assigned the following tasks:

1) Construct an accident sequence model for the designated initiating event (e.g. event tree for

MLOCA is assigned for working group #1 in accordance with Table 1).

2) Perform failure modes and effects analyses and develop fault tree models for the designated system

(e.g. power supply system for Group #3). 3) Develop systems models for other systems involved in the performance of safety functions. These

systems are modeled in a simplified manner (e.g. undeveloped event with transfers to support

systems). The simplified system models are developed by the groups that were more efficient in their dedicated tasks.

4) Quantify reliability parameters for all components and enter this information in the PSA model.

1 In this case, super-component (also called aggregate component) is a simplified component or system with limited

modelling capabilities, used to provide minimal feedback to the system being modelled.



5) Quantify systems models using PSA software and discuss the results obtained (e.g. validity if

minimal cutsets (MCSs), importance of particular basic events, etc.) 6) Document the analysis performed in the form of a section of a formal PSA report. The outline of

the PSA report is made available to the trainees.

Prior to starting the modeling work all groups are provided with the guidance on what should be included in the fault trees and a common coding scheme for naming basic events is agreed with all working groups.

PSA model integration and results analysis

After the working groups complete their assigned tasks, the results are thoroughly reviewed by trainers and

discussed with all trainees.

The next stage of the first practical training session is the model integration, analysis of the results and

obtaining the insights. These tasks are performed by all working groups in parallel.

The integration of the model is first performed by trainers, who identify and remove gaps in the model. The

model is then presented to the trainees, who will continue to utilize the same integrated model. The

following specific points are highlighted:

1) Following the integration of the model, the model is not yet ready to be quantified due to the

existence of ‘logic loops’. As the training groups have been using undeveloped events, these events

are replaced with actual links to support system fault trees. As a result, the following logic comes true (provided as an example): “service water system depends on power supply (e.g. diesel

generators (DGs)) => DGs in tern require service water for cooling”. This logic is known as “logic

loop” and must be removed in order to allow model to be quantifiable. During the training, the

trainers explain the problems associated with ‘logic loops’ to the trainees and help them to find the proper solution to remove “logic loops”. This is an excellent method to demonstrate the issue of

“logic loop”.

2) The “original” design of the simplified NPP is intentionally weak (e.g. there are interconnections between safety systems, no possibility to test systems during plant operation, etc.). The intention is

that after the model is integrated, the trainees will analyse the results, identify weaknesses in the

design, and suggest design improvements.

3) The proposed design improvements are further modelled and analysed through sensitivity studies. 4) Common cause failures are not modelled at the first training session. The reason is that the design

weaknesses are more evident for the trainees with limited experience in PSA technique and NPP

design when common cause failures do not mask the overall results.

Finally, each working group produces a section of a formal “PSA report” following the outline proposed by

experts.

Contents of the subsequent practical training sessions

When the training programme envisages several practical training sessions, at the conclusion of each practical training session (with the exception of the final session), homework is assigned to the working

groups by the trainers. The homework includes similar tasks that have been performed during the session,

but with slightly increased complexity. The content of multiple practical training sessions includes:

Session #2:

- Developing models of additional systems represented in a simplified form in the PSA model developed

at the first practical session (e.g. Main Feedwater System, Emergency Service Water System, Primary

and Secondary Depressurization Systems, High Pressure Injections System).

- Modelling design improvements aimed at removing design weaknesses identified during the first practical training session.



- Introduction of common cause failures.

- Human reliability analysis exercises and assessment of human error probabilities of a few modelled human actions.

Sessions #3: Modelling internal flood and fire scenarios (after the theoretical module on internal hazards

PSA)

5. APPROBATION OF THE PSA TRAINING PROGRAMME AND FURTHER PLANS

5.1 Approbation and Feedback

The training programme described in this paper has been implemented in two projects being led by the SAS/NSNI/NSS:

1) EBP NOR – aimed to enhance competence of nuclear regulatory authorities in Vietnam and

Malaysia. In this project all three practical sessions were successfully implemented.

2) EBP EC JRNC - aimed to enhance competence of regulatory authority in Jordan. In this project two practical sessions were successfully implemented.

The overall conclusion from the application of the IAEA PSA training programme is summarized below:

• Generally the trainees are enthusiastic and eager to learn

• Very good attendance of the training sessions has been observed

• Even after completion of the first practical Level-1 PSA training session, all trainees:

- felt comfortable with PSA software

- were able to develop reasonably comprehensive models

- were able to understand and interpret Level-1 PSA results

• The trainees developed a feeling of “ownership” of the PSA model and were ready to

independently work with the model during the assigned homework

The effectiveness of the training programme is confirmed by the fact that after the training was provided,

the Malaysian PSA team initiated a study to further deepen their PSA knowledge through developing a PSA for the Malaysian research reactor. This study is also supported by the EBP funded by Norway.

5.2 Further Plans

The theoretical training on Level 2 PSA is available. The work on developing Level-2 PSA practical

training module is on-going. However, this requires significant resources and will take some time.

The implementation of the practical training (already developed and being currently developed) requires

quite substantial time of IAEA staff, which is not always possible due to current workloads. Outsourcing of

the PSA practical training is being currently considered as a possible option.

Further actions will be dedicated to formalize the training programme and prepare the training modules and

material in a more sustainable format, so that the training could be performed by an outsourced organization with a limited involvement of IAEA staff. It is essential that the training programme is in compliance with

the IAEA Safety Guides on PSA [13], [14] and other technical publications in the area of PSA produced by

the IAEA (e.g. TECDOC-1511 [15]); this compliance will be continually provided. It is expected that the

work on preparation of the training material will be finished in 2014.

6. CONCLUSIONS

The PSA training programme developed by PSA specialists from SAS/NSNI/NSS puts an emphasis on the

practical simulation-type training on PSA. The developed programme has proven to be notably more

effective and efficient in training newcomer countries for the complex PSA techniques.



The developed training programme can also be used to train young engineers in any country; this is especially important in the light of fewer opportunities for young engineers to receive on-the job training in

PSA that is important for building in-depth knowledge and understanding the results of risk assessment.

The practical aspects highlighted in the paper provide useful information for the organizations interested in

organizing advanced training on PSA.

References

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Commercial Nuclear Power Plants (1975).

[5] NRC SOARCA Project, http://www.nrc.gov/about-nrc/regulatory/research/soar.html

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