Welcome to the Demo of Event analysis and Assessment of Human Reliability with CAHR. Continue by pressing any key; ESC to stop. CAHR means "Connectionism.

Welcome to the Demo of Event analysis and

Assessment of Human Reliability with CAHR.

Continue by pressing any key;ESC to stop.

CAHR means "Connectionism Assessment of Human Reliability" The Database-System CAHR is a tool for analyzing operational disturbances, which are caused by inadequate Human actions or organizational factors. It was implemented using MICROSOFT ACCESS. CAHR contains a generic knowledge base for the event analysis that is extendable by the description of further events. The knowledge-base contains information about the system-state and the tasks as well as for error opportunities and influencing factors (PSFs).

Demo Version, 7.2000

The method was first applied to the analysis of events in Nuclear Power Plants:• First Study 1994 to 165 for events in Boiling Water Reactors (BWR)• Second Study 1998 to 55 events in Pressurized Water Reactors (PWR)• Third Study 2000 to events with communication problems

The results of the method were used for:• The assessment of cognitive aspects in the safety assessments of Nuclear

Power Plants• The further development of methods for the analysis and assessment of

Human Reliability (HRA-methods), particular in the field of so-called „Errors of Commission“

Currently we are also developing the method for:• The prediction of cognitive errors in aircraft incidents• The prediction of human behavior in decision problems (in process industry

and transportation)

Event decompo-sition intoSub-Events

Analysis of the Information flow for- Organization- Communication

Assessment andOptimization

Event

Detailed Analysis of the Sub-Events using the Man-Machine System

Event-EvaluationError

Situational Conditions

Causes (PSFs)- organizational- ergonomical- technical- cognitive

Interrelationsof- Error and PSFs- different PSFs

- situational conditionsand error

or PSFs

MachineInformation processing

Situation

Operator

Action Con-trol

Task

Environment

System-outcome

Task-DispatchTask-Order

Feed-back

System-parameter

Per-ception

The method has an advanced view on the analysis and assessment of the

Humans’ role in technical systems.

General Procedure of the Method

CAHR is structured into Event Analysis

CAHR is structured into Event Analysis ....and.... Event Evaluation

Connecting link between both is the analysis structure of the Man-Machine System (MMS)

because it considers...

Organizational Aspects

Ergonomical Aspects

Cognitive Aspects

Technical Aspects

Situations

MMS 1.1: Type APerso n 1= O pe rato r

Persons

MMS 2 .2 : Type B Person2 =O peratorP lace=Contro l room

MM S 2 .3 : Type BPerso n3=O pe rato r

MMS 3 .2 : Type C Person2=Operator

M M S 3 .4 : Ty pe C Person4 =Mechanica l

Start of event

End of event

Tim e dependence of one person

Dependency of two persons at one p lace

LatentFa ilure

A ct ive Fa ilure

Place=Contro l room

Place=Contro l room

Place=Contro l room

Place= In the P lant

By combining several MMSan entire event can be described as a working-system.

The Philosophy of the method is:

Focus of analysis is the working system and not the human. Human blame or guilt is not an issue of analysis (or even distracts it).

Human error result from the interrelation of several situational and causal factors of the working system

The method uses a fixed structure but no fixed taxonomy (open method) and therefore is usable for any event or any technical area

Strict differentiation between observable information (phenotypes) and causes (genotypes) in the event analysis and description

General informationPlant and plant typeDate and time of the eventCategorization of the importance of the eventState of description of the event

The Case Description mages and describes generalinformation about the event.

Information for • affected systems

• whether is was a human error or • whether the human has coped with the event successfully

The Case Description also manages the event report.

Textual description of the event

Photos, further Information (via OLE-Objects)

The description of an event is implicative, i.e.: an error can only be described if there is some information already contained in the object and action column. The same holds for the PSFs. This ensures that the interrelations between observable information and errors and causes is represented correctly and hence it is clear where an error occurred and a PSF had been effective.

Now we enter the most interesting part:The analysis regarding human errors.

The input procedure works from general observable information (Object, Action) to errors and

influencing factors (PSFs)related to the categories respectively classes of the MMS.

The column „Element“ enables the analyst to describe additional information that is useful and important

for understanding the event

A punctuation mark is used to distinguish statements and to assure a correct representation of the information

regarding Object, Action, error and PSF.Maybe for instance that Valve A was opened too late

and Valve C was closed too early.

The relevant information for human actions are described interactively.

A Double-Click on the table provides us with the valid taxonomy for the class and aspect to

describe, here for instance: What are the error-types of activities?

Click...

Click...

The relevant information for human actions are described interactively.

Another step of event description

Events often consist of various sub-events:

• other persons involved• other phases of the event

• different places

For considering this we choose NEW

The relevant information for human actions are described interactively.

For a new sub-event

If the precaution measure should be described.

This is of importance, if one wants to compare the realized measure

and the real causes (what often is not equal).

For analyzing the cognitive aspectsof this sub-event.

The relevant information for human actions are described interactively.

Here the new sub-event thathas to be described using the

taxonomy

Here the precaution measureundertaken in this event

Now as we have analyzed and described such many events, what to do with them?

Evaluating of course!

CAHR performs this using:

• Simple queries regarding the events

• Qualitative analyses of the causes of human error

•Quantitative estimation for human error probabilities

Event 1 :

Event i :

Event n

At first it is desirable to get anoverview about frequencies, status of analysis etc.

Let us see how many events of Boiling Water Reactors (BWR) were

elaborated

and

which of them are errors and performances of Humans ...

Click and...

ErrorsPerformance

Quiet convenient to have Humans in the plant,isn’t it?

Would you blame an operator or speak about

Human Failure

considering such a portion of good performance?

At first it is desirable to get anoverview about frequencies, status of analysis etc.

Subsequently we can analyze the error deeper.Why do Humans make errors?

We get a more precise picture, if we analyze the events regarding a question of analysis we have e.g.:

Error of a certain group of personnel while operation a valve.

The procedure of defining the query is analog

to one of describing an event.

Click and...

We can combine different query items using logical relations like AND, OR, NOT

Subsequently we can analyze the error deeper.Why do Humans make errors?

... we find 23 equal cases in 220 events or 25 in 400 sub-events

...and of course uncertainties because an event is never described completely

But with CAHR we are able to come up with an estimation for the

Human Error Probability (HEP) that is - based on all performed studies -

compatible to the estimations of other methods like THERP for instance.

... with the extensive algorithm of the connectionism part of CAHR ...

Which cause leads to such an error?

Click and...

Subsequently we can analyze the error deeper.Why do Humans make errors?

... we find a series of causes in the areas of •Organization

•Cognition•Ergonomics•Technique

which led to the error in their interrelationships.

... the frequencies

... and the relative frequencies

This enables a decision whether there are systematic errors and to find the optimal

improvement measures.

But, be aware of the interrelationships - the factors do interact with each other

No event is like the other!

Quiet different terms are necessary to describe them sufficiently with

all the individual relationships.

Therefore, a taxonomy has to be proofed and revised anyway after each event.

The variability of the events is covered by the fact that CAHR only prescribes the description

structure and not the taxonomy.

To deal with this openness in the event-evaluation, CAHR has some tools:

• A class-editor• A taxonomy-editor

Using the Class-Editor different descriptors can be combined

... For instance we can definea class for different persons

In the evaluation of events we now are able to use a class in the same way as we can use the original descriptors.

Using the Taxonomy-Editor, descriptors can be changed or

new descriptors can be implemented

Operational experience

Module for HRAProbabilistic data

Interface

Event-Input Module for Diagnosis

Factors and Causes

HRA / Qualitative Analysis

dataQualitative

User-Output

Event

Possible factors and causes

Connectionism Data-base

Causedescription

Situational Pattern

Question of Analysis

User-Input

Events Taxonomies

Class Editor

Event-Database

Query

Summary of the method CAHR

ACCESS

What can you do with CAHR?

If you want to have a retrospective view into the past, you can...

• ...analyze and describe various events in a systematic manner...

• ...even from different technologies

If you want to have a prospective view into the future, you can...

• ...can understand the relationships of factors leading to the error chain of an event

• ...look for causes and situational conditions of importance for human errors

• ...make safety assessments of human errors in risk analysis

• ...find precaution measures for your system and assess the quality and effectiveness of them

• ...improve and optimize precaution measures in your system

We hope you have enjoyed the tour.

• Sträter, O. (1997) Beurteilung der menschlichen Zuverlässigkeit auf der Basis von Betriebserfahrung. GRS-138. GRS.

Köln/Germany. (ISBN 3-923875-95-9)• Sträter, O. & Bubb, H. (1998) Assessment of Human Reliability based on Evaluation of Plant Experience: Requirements

and their Implementation. Reliability Engineering and System Safety. Elsevier. Vol. 63, No. 2, p. 199-219. • Reer, B., Sträter, O., Dang, V. & Hirschberg, S. (1999) A Comparative Evaluation of Emerging Methods for Errors of

Commission Based on Applications to the Davis-Besse (1985) Event,. PSI. Schweiz. Nr. 99-11 (ISSN 1019-0643)• Sträter, O. & Reer, B. (1999) A Comparison of the Application of the CAHR method to the evaluation of PWR- and

BWR-events and some implications for the methodological development of HRA. In: Modarres, M. (Ed). PSA‘ 99 - Risk-

Informed Performance-Based Regulation. American Nuclear Society. LaGrange Park, Illinois, USA.

Do you desire to analyse and assess human errors? We would be pleased to assist you.You are interested in this data-base? We would be pleased to make an offer.

Kontakt & Entwicklung:

Prof. Dr. Oliver Straeter Universität Kassel Fachbereich Maschinenbau Arbeits- und Organisationspsychologie Heinrich-Plett-Strasse 40 D-34132 Kassel Tel: +49 561 804 4211 eMail: [email protected]