ALARP concept

Thus far, this chapter has dealt with hazards, risks, probability, and severity. In applying the ALARP concept, economics is brought into the decision making. ALARP may be defined as follows ALARP is that level of risk which can be further lowered by an increment in resource expenditure that cannot be justified by the resulting decrement of risk. 

ALARP concept basically comes from the British health and safety system (Act 1974)- It is not in true sense a quantitative method, although cost—benefit analysis is often used to get ALARP. It is a challenging subjective method, as it requires duty holders and others to exercise their judgment very carefully. In risk analysis, three factors play important role, viz. trouble, time, and cost. The breakeven point in... 

The ALARP concept (as low as reasonably practicable) is discussed with an example of how the concept is applied in achieving an acceptable risk level. 

Several depictions of the ALARP concept begin with an inverted triangle, the purpose being to indicate that the risk is greater at the top and much less at the bottom. Figure 6.2 shows the concept combined with the elements in the risk assessment matrix. 

The accident scenarios may consist of the hazards, intermediate events, additional events and consequences. It is important to define the initial events (hazards). The measure of safety of ships in damage conditions is the risk level. The risk acceptance criteria can be the risk matrix or ALARP concept. 

The criteria within the method is to achieve an adequate level of risk using the risk acceptance criteria, risk matrix or ALARP concept, Gerigk (2010). 

The second major issue raised in this paragraph is to do with the word unacceptable . If risks are to be categorized for acceptability then some objective criterion is needed. Most companies use a simple risk matrix, such as that shown in Chapter 1 to determine which hazards are acceptable, and which are not. A more sophisticated approach is to use the ALARP concept. 

ARIBA then produced a matrix (Table B.12) indicating how the ALARP concept might be integrated into this framework. The three regions indicate the management decision-making and action required ... 

On this basis the concept of so far as is reasonably practicable (SFAIRP) was bom and subsequently enshrined in the 1974 UK Health and Safety at Work Act. SFAIRP, whilst a significant step forward, fails however to precisely acknowledge the notion of risk and its relationship to practicability. As such the slightly modified term as low as reasonably practicable (ALARP) has been widely adopted in the UK and some other countries as the basis for risk acceptability. The ALARP principle can be defined as that level of risk which can be further lowered only by an increment in resource expeuditure that is disproportionate in relation to the resulting decrement of risk [2],... 

Note that there is no real concept of temporary ALARP , one cannot accept a non-ALARP solution whilst a permanent ALARP alternative is sought. A particular control may offer a temporary fix but the resulting risk is either acceptable or not at a given point in time. 

Some risk analysts use the term as low as reasonably practical (ALARP) for setting a value for acceptable risk. The basic idea behind this concept is that risk should be reduced to a level that is as low as possible without requiring excessive investment. Boundaries of risk that are definitely acceptable or definitely not acceptable are established as shown in Figure 1.16, which is an FN curve family. Between those boundaries, a balance between risk and benefit must be established. If a facility proposes to take a high level of risk, then the resulting benefit must be very high. 

The fundamental difficulty with the concept of ALARP is that the term is inherently circular and self-referential. For example, the phrase best available technology used in the list above can be defined as that level of technology which reduces risk to an acceptable level— in other words to the ALARP level. Terms such as best operations and high standard are equally questionbegging. 

The safety case concept requires that operators demonstrate that the systems and processes they have adopted ensure that their facility is sufficiently safe for all those people who are possibly impacted by their activities (workers and contractors at their facility, passengers and customers, people who live and work in surrounding areas). Most safety case regulations require the demonstration to take the general form of showing that risk is as low as reasonably practicable, or ALARP (or that risk has been reduced so far as practicable - SFAP). Clearly, safety cases are an example of the broad trend towards risk-based regulation (Hood et al. 2004). 

The concepts inherent in the terms ALARA and ALARP serve as guidelines in determining whether a risk is acceptable, but cannot be used as absolutes in decision-making. It should be understood that in an exceptional situation, even though the risk level attained is as low as reasonably achievable or practicable, a decision will be made that the residual risk is not acceptable and that the operation should not proceed. 

The concept embodied in the terms ALARA and ALARP applies to the design of products, facilities, equipment, and the work environment. (If there is a substantive difference between the intent of ALARA and ALARP, it s difficult to establish.)... 

In the AOP 52 for the calculation of the SSCI it is necessary to know the severity of a hazard. It is categorized in four categories catastrophic, critical, marginal and negligible. These categories are not explicitly defined in the AOP 52 so we guess that these terms can be defined by the user depending on the application, e.g. in the definition of the ALARP approach. This leaves room for interpretations. This holds also true to a lesser extent for the concept of software autonomy of the AOP 52. 

Example of ALARP and whole life safety concept... 

NOTE The examples below are not meant to be complete ALARP assessments, but may be taken as indicative of the concept of use. The risk situations considered may be chosen as required and could even be different phases of the same procedure. 

It is suggested that the four components of the Accident Tetrahedron may be considered as a new concept of separate lines of defence or layers of protection when considering ALARP Justifications, all of which must be considered during risk assessments. Further research is recommended on the costs of mitigation methods across the four areas of the tetrahedron. A specific retrospective application would also have benefit. 

As we proceeded with our studies, we found that developing a distinct, perhaps statistical, universally applicable definition of acceptable risk that did not contain general and judgmentally interpretive terms is not possible. But, with a studied understanding of risk, and risk taking, and the concept of As Low as Reasonably Practicable (ALARP), I dare to offer a practical definition of acceptable risk that can be effectively applied when dealing with workplace hazards, risks, and deficiencies in safety and health management systems. 

The concept of ALARP helps with respect to the economic considerations necessary in risk decision making. A good and easily understood definition of ALARP may be found in the draft of MIL-STD-882E, the Department of Defense Standard Practice for System Safety ... 

ALARP is a sound concept. It promotes a management review that should result in achieving acceptable risk levels. Practical economic and risk trade-offs are frequent and necessary in the benefit/cost deliberations that take place when determining whether the costs to reduce risks further can be justified by the resulting decrement in risk. ... 

The concept of As Low as Reasonably Practicable (ALARP) was recognized as a valuable tool in determining acceptable risk levels. However, a word of caution was offered On occasion, achieving risk levels as low as reasonably practicable will not be acceptable. Prior to presenting the following definition, I said that a workable and sound definition of acceptable risk must encompass hazards, risks, probability, severity, and economics ... 

The concept of ALARP must of course be applied with due regard to the Annex ZA of EN ISO 14971 2012, which excludes the possibility of not implementing risk control measures on the basis of economic considerations (risk reduction of As Far As possible) in compliance with the requirements of Directive 93/42 / EEC. 

In order to provide a measure for allowable risk, companies use the concept of As Low as Reasonably Practical risk. This term is usually abbreviated to ALARP (sometimes facetiously referred to As Low as Regulators Permit ). Other terms that have the same general meaning are As Low as Reasonably Achievable (ALARA) and So Far as Is Reasonably Practicable (SFAIRP). 

Management has to decide if the calculated level of risk is acceptable, and, if it is not, what actions need to be taken to reduce it. Some Safety Management Systems—in particular many Safety Cases—are built around the concept of a numerical value for an ALARP (As Low as Reasonably Practicable) value, as already discussed. If the risk lies above or below the predetermined ALARP value then corrective actions must be taken. 

Both these abbreviations are in use. In HSE.gov.uk it is used as SFAIRP. In Clause 4.3 of Chapter 1 ALARP has been discussed. As per HSE.gov.uk they essentially mean the same thing, the core concept being reasonably practicable. The term balances... 

The ALARP region lies between acceptable and intolerable, in which the system developer is required to reduce the risk to be as low as reasonably practicable (ALARP). lEC 61508 directs towards ALARP. Eor the concept of ALARP, refer to Chapter I. 

ALARA and ALARP are commonly used acronyms in risk assessment and risk reduction literature. ALARA stands for as low as reasonably achievable. ALARP is short for as low as reasonably practicable. Use of the ALARA concept as a guideline originated in the atomic energy field. This is taken from the Reference Library, Glossary of Terms at www.nrc.gov (ALARA, 2007). 

A key development in system safety is the ALARP principle that states that the residual risk of a system shall be as low as reasonably practicable (ALARP principle) and was codihed through the UK Health and Safety at Work Act of 1974. The concept asserts that safety-critical systems and operations should be safe as far as reasonably practicable without risks to health and safety. This is important because it forces the overt decision to balance the realized safety benehts to the actual costs to implement in other words, residual risks are tolerable and thus do not need further mitigations. 

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