PART 1 2 HAZARDS, RISKS & SAFETY.

Transcription

1 PART 1 2 HAZARDS, RISKS & SAFETY arshad@utm.my 1

2 Types of Hazards Definition of Risk & Safety Content 2

3 Hazard 3

4 Hazards A "source of danger" is a property, a situation, or a state. It is not an event but a prerequisite for the occurrence of a hazardous event that may lead to harm to an asset. A hazard is often, but not always, related to energy of some kind 4

5 Classification of Hazards based on contributors Technological hazards e.g.,related to equipment, software, structures, etc Natural (or environmental) hazards e.g., flooding, earthquake, lightning, storm, high / low temperatures Organizational hazards e.g., long working hours, inadequate competence, inadequate procedures, inadequate maintenance, inadequate safety culture Behavioral hazards e.g., drugs/alcohol, lack of concentration Social hazards e.g., hacking, theft, arson, sabotage, terrorism, war 5

6 Threats Asset Value Threat & Threat agents Threat Picture Vulnerability Asset value. The value of the asset determined by its importance to the system or the operation. It is sometimes difficult to quantify the value since it cannot always be assigned a monetary value Threat and threat agents. This is represented by the external or internal persons who have the intention and capacity of harming, compromising, or stealing the asset specified. Vulnerability: technical, organizational, human, or routine failures and deficiencies that threat agents may exploit 6

7 Vulnerability The consequence of hazard occurrence often results in many different damages Life Property Environment Business Money Etc To access the overall impact, all impacts are converted into common value à Money/Costs 7

8 Active & Latent Failures Failures may also lead to Hazardous Conditions Active failures are events that trigger unwanted events. Examples: violations and errors by operators Latent conditions do not trigger an accident immediately, but they lie dormant in the system and may contribute to a future accident. Example: Poor design maintenance etc 8

9 Events Event: Incident or situation which occurs in a particular place during a particular interval of time Initiating event : An identified event that upsets the normal operations of the system and may require a response to avoid undesirable outcomes Hazardous Event: The first event in a sequence of events that, if not controlled, will lead to undesired consequences (harm) to some assets 9

10 Accidents Scenario Accident Scenario: A specific sequence of events from an initiating event to an undesired consequence (or harm) The path in an accident scenario is diverted as barriers are activated 10

11 Probability Probability is a complex concept about whose meaning many books and scientific People have argued about the meaning of the word "probability" for at least hundreds of years, maybe thousands. So bitter, and fervent, have the battles been between the contending schools of thought, that they've often been likened to religious wars. And this situation continues to the present time (Kaplan,S(1997). The words of risk analysis, Risk Analysis, 17 (4), pp ) 11

12 4 Views of Probability Statistician ( frequency or fraction. ) The outcome of a repetitive experiment of some kind, like flipping coins. It includes also the idea of population variability. Bayesian (probability) The degree of confidence or degree of certainty, does not exist in the real world, it exists only in our heads. For that reason it s often called subjective probability. Mathematician (probability) A probability curve is a mathematical abstraction. He is interested in the formal properties of such curves independent of their interpretation. 12

13 Probabilities - Classical Approach Classical Approach An outcome is the result of a single experiment, and a sample space S is the set of all the possible outcomes. An event E is a set of (one or more) outcomes in S that have some common properties. When an outcome that is a member of E occurs, we say that the event E occurs. 13

14 Example: Flipping a coin When you flip a coin. The experiment has n = 2 possible outcomes and the sample space of the experiment is S = {H, T}, H means that the outcome is a head, and T that it is a tail. We assume that the coin is fair in the sense that both outcomes have the same probability of occurring. We want to find the probability of getting the event E = {H}. The probability of E is therefore Pr(E) = ne n =

15 Example: Rolling two fair dice You roll two dice, one red and one blue. In this case, there are n = 36 possible outcomes and the sample space is (1,1) (1,2) (1,3) (1,4) (1,5) (1,6) (2,1) (2,2) (2,3) (2,4) (2,5) (2,6) (3,1) (3,2) (3,3) (3,4) (3,5) (3,6) S = (4,1) (4,2) (4,3) (4,4) (4,5) (4,6) (5,1) (5,2) (5,3) (5,4) (5,5) (5,6) (6,1) (6,2) (6,3) (6,4) (6,5) (6,6) The event E I = "same number of eyes on both dice has n E I = 6 Pr(E) = n E 1 n = 6 36 = 1 6 The event E 2 = the sum of eyes is 9. In this case, n E 2 = 4 Pr(E) = n E 2 n = 4 36 =

16 Probabilities Bayesian Approach Thomas Bayes ( ), An essay towards solving a problem in the doctrine of chances (Bayes, 1763). British. Subjective Probability: A numerical value in the interval [0, I] representing an individual's degree of belief about whether or not an event will occur The degree of belief about an event E is not arbitrary but is the analyst's best guess based on available knowledge K about the event. The probability of the event E, given knowledge is K, should therefore be expressed as Pr(E K )! 16

17 Bayesian: Prior Probability Prior Probability: An belief in the occurrence of an event E prior to any additional collection of evidence related to E Pr(E D 1 )= Pr(E). Pr(D E) 1 Pr(D! 1 ) which is a simple consequence of the multiplication rule for probabilities! Pr(E D 1 )= Pr(E D 1 ).Pr(D 1 )= Pr(D 1 E).Pr(E) Posterior Probability: A belief in the occurrence of the event E based on prior belief and some additional evidence D I. Pr(E D 1 D 2 )= Pr(E). Pr(D E) 1 Pr(D! 1 ).Pr(D E) 2 Pr(D 2 ) 17

18 Probabilities - Frequentist Approach De Finetti (1974): My thesis, paradoxically, and a little provocating, but nevertheless genuinely, is simply this PROBABILITY DOES NOT EXIST. In risk analysis, it is not realistic to assume that the events are repeatable under essentially the same conditions. We cannot, for example, have the same explosion over and over again under the same conditions. This means that we need to use the Bayesian approach. However, there is an ongoing controversy about the interpretation of the subjective probability. There are two main schools: Subjective probability is subjective in a real sense. Two individuals will generally come up with two different numerical values of the subjective probability of an event, even if they have exactly the same knowledge. Subjective probability is dependent only on knowledge. Two individuals with exactly the same knowledge K will always give the same numerical value of the subjective probability of an event 18

19 Frequency The frequency of an event in the time interval (0. t) is given by f t (E)= n (t) E! t The time t may be given as calendar time, accumulated operational time, accumulated distance etc. If the situation is kept unchanged, the frequency will approach a constant limit when t à. We call this limit the rate of the event E and denote it by! λ E = lim x n E (t) t! λ E 19

20 Consequence and Harm Harm: Physical injury or damage to health, property, or the environment (IEC , 1995) Consequence Categories Loss of human life - Personal injury, Reduction in life expectancy, Damage to the environment (fauna, flora, soil, water, air, climate, landscape), Damage to material assets, Investigation and cleanup costs, Business-interruption losses, Loss of staff productivity, Loss of information, Loss of reputation (public relations), Insurance deductible costs, Fines and citations, Legal action and damage claims, Business-sustainability consequences, Societal disturbances, Consequences related to so-called "soft values," such as reduction of human well-being and loss of freedom. 20

21 Loss Spectrum C 1 L(C 1 ) p 1 Hazardous Event C 2 L(C 2 ) p 2 C 2 L(C 3 ) p 3 A hazardous event leading to consequence spectrum C s with losses of L(C s) 21

22 Risks 22

23 Risks Risk: The combined answer to three questions:(1)what can go wrong? (2)What is the likelihood of that happening? and (3) What are the consequences?! R = { s, f,c } n i i i i=1 S is event sequence, f is failure rates, C is consequence Risk: Combination of the frequency, or probability, of occurrence and the consequences of a specified hazardous event (IEC , 1995) Risk influencing factor (RIF): A relatively stable condition that influences the risk Operational Organizational Regulatory and customer-related 23

24 Risks Desired risk: Risk that is sought, not avoided, because of the thrill and intrinsic enjoyment it brings. Inherent Risks: Risk that an activity would pose if no controls or other mitigating factors were in place (the gross risk or risk before controls) Residual risk: The risk that remains after engineering, administrative, and work practice controls have been implemented 24

25 What is Risk? a situation involving exposure to danger expose (someone or something valued) to danger, harm, or loss Risk = Likelihood x Severity Likelihood of occurrence - Frequency - Probability Severity of the Consequence - Fatality, loss, illness, etc. - Coverage 25

26 Definition of Risk Risk = Likelihood x Severity = Probability x Cost = Vulnerability x Threat x Cost Inherent Risks: Risk when no control or mitigating factor in place Inherent Risk = Cost x Threat Residual Risk: Risk that remains after controls are taken Residual Risk = Cost x Threat x Vulnerability Costs: Money, opportunity, reputation, 26

27 Types of Risk Strategic Goals of the Organization Safety Human & Asset well-being Well-being Operational Processes that Achieve Goals Financial Safeguarding Assets Compliance Laws and Regulations Reputational Public Image etc Risk cannot be eliminated, it can only be managed! 27

28 Safety 28

29 Safety Performance Safety performance: An account of all accidents that occurred in a specified (past) time period, together with frequencies and consequences observed for each type of accident Risk influencing factor (RIF): A relatively stable condition that influences the risk. 29

30 Barriers & Mitigation Barrier: Physical or engineered system or human action (based on specific procedures or administrative controls) that is implemented to prevent, control, or impede energy released from reaching the assets and causing harm Mitigation: Action to reduce the severity, seriousness, or painfulness of something. 30

31 Uncertainty Aleatory uncertainty. This is uncertainty due to natural variation and intrinsic randomness. Also called random uncertainty E.g. wind speed, precipitation, and product quality. Epistemic uncertainty. This type of uncertainty comes from lack of knowledge. also called subjective uncertainty. e.g., concern the health effects of nanoparticles and the effect of CO2 discharges on global warming. Epistemic uncertainty can be reduced by knowledge acquisition and is therefore referred to as reducible uncertainty. 31

32 Vulnerability & Resilience Vulnerability: The inability of an object to resist the impacts of an unwanted event and to restore it to its original state or function following the event Resilience: The ability to accommodate change without catastrophic failure, or the capacity to absorb shocks gracefully 32

33 What is Safety? The term in its human context has no meaning except in relation to potential risk of harm. It is essentially a relative term, the complement of risk Report 2 Royal Commission on Ocean Ranger Marine

34 What is Safety? A state in which or a place where you are safe or not in danger or at (Cambridge dictionary online ) The condition of being protected or unlikely to cause danger, risk or injury (oxford dictionary) Freedom from those conditions that can cause death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment (MIL-STD-882D (2000)) A state where the risk has been reduced to a level that is as low as reasonably practicable (ALARP) and where the remaining risk is generally accepted.

35 The Meaning of Safety Perhaps Safety should be defined as the antonym of Risk! RISK SAFETY Improving Safety by Reducing Risks! So, managing safety is essentially managing risks

36 End of P1-L2 36