atw 2018-03v6


atw Vol. 63 (2018) | Issue 3 ı March

Determination of greater defense

barriers, lower costs, Selection of

limiting cases for detailed quantitative

analysis, less energy dissipation, Performance

of detailed quantitative

analysis for each limiting case, Evaluation

of compliance to the acceptance

criteria and safety margins, etc.


In general, when the analysis of

nuclear accidents are separately done

by deterministic and probabilistic

approaches are faced with shortcomings

and drawbacks. It is not

possible to provide a comprehensive

prediction for nuclear accidents. In

deterministic approach, many effective

factors in the event are not considered

but in probabilistic approach,

most effective factors in the event are

used for determining the frequency of

occurrence and total error. Therefore,

for better understanding and comprehensive

analysis of events, deterministic

and probabilistic assessment

is necessary at the same time.

This review indicates that the integrated

risk-informed approach has

great potential to improve safety level

by using probabilistic and deterministic

approaches. By using IRIDM

approach, determining of initiating

events, multiple failures and event

sequences are possible. The final decision

should be based on integrated

risk-informed rather than the risk,

itself. Risk assessment should only

be part of the decision process. For

the final decision, integrated risk

informed should be based on combination

of deterministic and probabilistic


Adopting an IRIDM model is way

of helping prevent these incidents and

accidents as well as other benefits

such as:

• Safer and more secure operations

have reduced risks through more

comprehensive understanding of

operational risks;

• Greater resilience, including the

ability to cope with unforeseen

threats and adverse events;

• Better integration of operations

and technical systems, with financial

and human resource management;

• Greater efficiency, including more

productive operations, higher staff

morale, lower staff turnover, more

efficient and effective control


• Greater ability to identify weaknesses

so that they can be actively

corrected to prevent opportunities

for accidents to happen.


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Environment and Safety

The Importance of Integration of Deterministic and Probabilistic Approaches in the Framework of Integrated Risk Informed Decision Making in Nuclear Reactors

Mohsen Esfandiari, Kamran Sepanloo, Gholamreza Jahanfarnia and Ehsan Zarifi

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