Critical Risks Method (CRM): A New Safety Allocation Approach for a Critical Infrastructure

Gianpaolo Di Bona,Domenico Falcone,Luca Silvestri,Antonio Forcina

doi:10.3390/su12124949

Gianpaolo Di Bona, Domenico Falcone + Show 2 more

Open Access

https://doi.org/10.3390/su12124949

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Abstract

In the current research, a safety allocation technique named the Critical Risks Method (CRM) has been developed. Starting from a literature review, we analyzed the shortcomings of conventional methods. The outcomes show the primary two criticalities of the most important safety allocation approaches: (1) They are developed for series configuration, but not for parallel ones; (2) they ordinarily give only qualitative outputs, but not quantitative ones. Moreover, by applying the conventional methods, an increase in safety of the units to ensure the safety target leads to an increase of the production costs of the units. The proposed strategy can overcome the shortcomings of traditional techniques with a safety approach useful to series–parallel systems in order to obtain quantitative outputs in terms of failures in a year. The CRM considers six factors that are able to ensure its applicability to a great variety of critical infrastructures. In addition, CRM is described by a simply analytic definition. The CRM was applied to a critical infrastructure (Liquid Nitrogen Cooling Installation) in a nuclear plant designed with series–parallel units. By comparing the CRM outputs with databank safety values, the proposed method was validated.

Highlights

Safety Instrument Systems (SISs) are units designed to ensure the safety of people and the environment
Starting from the above considerations, we proposed a new safety allocation technique in order to solve the limitations of conventional approaches
The results show how the safety target influenced the allocated values [24] during the working and maintenance phases [25]

Summary

Introduction

Safety Instrument Systems (SISs) are units designed to ensure the safety of people and the environment. The international standard IEC 61508 [1] gives a safety approach to evaluate safety targets. The standard gives a hazard analysis to evaluate the safety requirements of units. Starting from the safety target of the whole system, it is necessary to evaluate the safety value of the units This approach is called safety allocation in IEC 61508. The LOPA technique was presented by the Center for Chemical Process Safety (CCPS) (1993) for industrial processes [8]. This methodology can be incorporated with a Hazard and Operability study (HAZOP).

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