ALARP principle

This provided a rational basis for storage-tank sizing and inventory levels and was also used to demonstrate compliance with the ALARP principle. 

Applied is the ALARP-principle—risk should be as low as reasonably possible. 

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],... 

Great Britain <1 no action required 100 - 1 further action required observing the ALARP principle (as low as reasonably nactical)... 

The ALARP principle is applied for events in the intermediate area. For those near the broadly acceptable limit, the risks are considered tolerable if the cost of risk reduction would exceed the improvement gained. For those near the maximum tolerable hmit, the risks are considered tolerable only if risk reduction is impracticable or implementation of risk reducing measures would lead to disproportionate costs compared with safety benefits gained. 

The ALARP principle is often applied, involving a safety goal with a hmit (maximum acceptable risk) and an objective (broadly acceptable risk). 

According to the ALARP principle, described in a general way in lEC 62278, three areas of risk, divided by certain limits, have to be considered ... 

In the nuclear energy industry, the scope of risk criteria includes the whole range of risk criteria from societal and individual risk, off-site radioactive release, reactor core damage accident and lower level criteria to mnnerical criteria used in various risk-informed applications. Risk criteria have variable status in different coimtries strict regulatory limits are defined in few coimtries, while indicative target values are used in most coimtries. The ALARP principle is sometimes applied, involving a risk criterion with a limit and an objective. 

According to the ALARP principle much effort should be used to identify and implement risk reducing measures in the ALARP zone. For the actual LNG plant the QRA per September 2008 shows a risk picture more or less in the middle of the ALARP zone , hence strong effort was necessary to reduce the risk level. During the autumn of 2008 the QRA was used to identify important risk scenarios where risk reduction measures could be identified. Three major risk contributing scenarios were considered in particular ... 

If X] xo, the situation is considered acceptable, but the possibility of removing the failure cause should anyhow be considered (ALARP principle). 

If X] < Xo, the situation is acceptable - and less frequent proof testing may in some cases be con sidered (see step 4). The ALARP principle stiU applies. 

FIGURE 12.10 Frequency/consequence safety criteria and ALARP principle for the collective risk. 

One of the first questions to be addressed in the safety programme was the definition of the safety target for the project. lEC 61508 does not directly address the question of how to do this, although many of its examples are based on the assumption that risks will be reduced As Low as Reasonably Practicable (ALARP). This is understandable given that applying the ALARP principle is a duty of all employers under the Health and Safety at Work etc Act 1974 (HSWA). 

However, the HSWA does not place a duty on highways authorities to achieve ALARP as far as members of the public are concerned. If the ALARP principle were applied to roads to the same extent as the railways, for example, the costs could increase substantially. Furthermore, it is unlikely that the measures that would be... 

This Rule of Law underpins the ALARP principle that risks must be reduced. As... 

The HSWA, and therefore the ALARP principle, apply by law to the management of safety on Britain s railways. 

There are circumstances in which substantial investment is required to deliver an improvement - for example, when costly technology is available that will reduce the likelihood of a human error escalating into an accident. For the ALARP principle to be applied in such circumstances, it is... 

The railway industry s interpretation of reasonable practicability as applied to investment decisions, described above, has been used across the industry for some years. However, it is not without its critics - some suggest, for example, that the railway industry s interpretation of the ALARP principle places too much emphasis on CBA and the quantitative comparison of risks versus costs. Moreover, recent developments have raised serious issues about the tenability of this approach. 

The risks shall be reduced to the lowest practicable level the ALARP principle. The principle considers also that the complexity of any mitigation can result in an additional source of risk beeause it ean cause defects or misuse or it can imply a delay in availability, with a potentially serious impact on public health. Risk management progressively and iteratively identifies mitigation, verifies the efficacy, and assures the balance between protections and their complexity or inconvenience for design and use. 

The risks are so great that it must be avoided, that is, refusal (unacceptahle region in ALARP principle as in Fig. 1/4.3-1). 

Risk is so small, it can be neglected instead of spending resources or effort to reduce (i.e., acceptable zone in ALARP principle Fig. 1/4.3-1). 

Complete application of the ALARP principle fully and accurately is very expensive and time-consuming [6]. 

S. Hughes, Gost Effective Application of ALARP Principle, Safety Engineering Group ERA Technology. 

The approach that is being widely promulgated in the UK is that the general form or framework for acceptability criteria should be represented as a three-tier system with (a) an upper bound on individual or societal risk levels, beyond which risks are deemed unacceptable (b) a lower bound on individual or societal risk levels, below which risks are deemed not to warrant concern and (c) an intermediate region between the previous two, where further individual and societal risk reduction are required to achieve a level deemed as low as reasonably practicable, the so-called ALARP principle. To achieve a wide consensus on the acceptable flood risk, it is indispensable that the various methods, rules, and tools to be developed in the advanced ALARP framework are robust and transparent. ... 

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. 

The UK Health and Safety at Work Act 1974 defined the concept of as low as reasonable practicable (ALARP). The ALARP principle is based on reasonable practicability, which simply means that hazard controls are implemented to reduce residual risk to a reasonable level of practicality. For a risk to be considered ALARP, it must be demonstrated that the cost in reducing the residual risk further would be grossly disproportionate to the benefit gained. Therefore, a risk assessment is conducted, and a cost-benefit analysis performed to determine how far to carry the hazard control. Of course, the challenge is deciding what is practical (e.g., cost, effort, time) balanced with how much benefit of lower residual risk the hazard control brings. Unfortunately, there is no standard method to demonstrate that the hazard control trade-off will meet ALARP. However, some of the following have been successfully used ... 

The final part of this ALARP assessment of the design investigates whether further reduction in risk would be cost-effective. Several potential enhancements were identified, the Severe Accident Mitigation Design Alternatives (SAMDA), but only one of these was taken forward in the generic AP 1000 because the others were not cost-beneficial based on ALARP principles. A quantitative cost-benefit analysis is applied to each of the SAMDA options, to show that its non-inclusion is ALARP for the APIOOO design proposed for the UK. 

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