Risk analysis. 6 question method

Schools do not yet have a separate subject as an engineer. But technical thinking can be trained in technology or even in social studies. Physics and chemistry teachers can adapt the 6-question method for group work.

An important aspect of engineering thinking is the ability to develop possible scenarios in emergencies, even at the system design stage. The six-question method is one way to look at the risk analysis problem from several angles.

The essence of the method is to get answers to questions that start with six questionable words. Each question is drafted in at least two directions. The first is the fight against the consequences, the second is the need for a “B” plan for the functioning of the interconnected systems. It is important to show causation and try to make it clear that the design of utility networks involves taking into account different risks. An example is when a storm wind left hundreds of households without electricity. It should be noted that a similar situation is repeated from year to year in different parts of Estonia.

What?

It should be noted that the modeling of accident scenarios and the analysis of risks focus more on the elimination of the consequences of the accident than on the development of a “B” plan, although both aspects are equally important. The first question is direct: “What happens in an area where electricity was lost?” The answer is obvious. The methodology for asking Plan B questions is simple, although it requires clarification. We add the word “no” before the verb – we get the question: “What is not happening in an area where electricity has been lost?” The wording of the question is not very clear. Let’s figure it out. There are many answers to this question that require separate investigation. If the electricity goes out, it will be impossible to refuel at the petrol station, which means that rescuers will have a problem if they run out of fuel and a fire breaks out. For hospitals, it is a question of transporting seriously ill patients with the inclusion of helicopters to other hospitals where there is no problem. When drug freezers are turned off, some drugs must be destroyed because they lose their properties or become dangerous. Therefore, it is necessary to check the existence of write-off certificates in pharmacies and medical institutions, this also applies to grocery stores. This means that if store managers receive information on long-term remediation, they will most likely be able to handle the logistics of delivering perishable products.

When the electricity is switched off, the water pumps stop working, which means that there is no water in the tap. If the elimination of the accident lasts longer than 6 hours, it is necessary to offer the residents the opportunity to obtain water from the aquifer. At the same time, the social services department should help people with disabilities or elderly people living alone, as it may be impossible for them to bring water from the street, especially if they live in a house with a lift above the ground floor. Therefore, social workers can interview neighbors in advance to provide emergency assistance to people living nearby. And the elevator service should be puzzled by checking those houses that do not have a dispatcher warning sensor in case of an emergency stop when people are in elevators. The city government or local government must have a list of hazardous industries. Some technological processes are irreversible if they are interrupted (eg in metallurgy, chemical industry). In the case of large cities, this problem is also linked to the release of people from the metro or amusement park rides, as well as to the increased risk at airports, congestion because the traffic lights do not work either. Anything used with forced ventilation will also not work. This circuit involves the risk of carbon monoxide poisoning if the diesel generator is used in a poorly ventilated area.

Communication is needed to coordinate activities. Mobile stations have redundant power supplies, but their operating time is limited. This time must be known. In the first hours of an accident, it is necessary to gather complete information about the problems. In some countries, such as Norway, in addition to sending SMS to mobile devices, they are building public warning systems via street mobile speaker multipliers. By the way, when I shared with a Norwegian specialist at a security conference that warning systems were already widely used during the Soviet Union, he was very surprised. Almost every apartment had a radio socket and a speaker was connected to it, through which state radio could be heard. Emergency mode was also offered, even for the radio turned off. The Norwegian specialist noted that it is very expensive and Norway cannot afford it, but if it could, it certainly did.

Where?

The next question is, “Where do they not occur?” To answer this question, it is often necessary to go beyond national borders and turn to the world’s experience. In Denmark, for example, power lines are usually laid underground. Of course, the replacement of utility networks is costly, but strategic objects can be identified and this requirement can be taken into account in urban planning and the construction of the same filling stations for rescuers, fire departments, police stations, hospitals, which should be connected underground.

When?

When do power outages usually occur? This is important for budgeting electricians or scheduling vacations. On the contrary, to determine when the reserve is needed. Almost all processes have their inertia. However, knowing the forecast, you can start acting before the event itself. In some cities, utilities have already adopted this practice and learned to clean or cover the roads with a reagent that is not yet covered with ice crust before the snow begins. This approach provides much greater efficiency because the driver needs time to reach the car base and then the snow thrower takes time to reach the designated location from the car base. When the traffic is stopped, it is very difficult for the driver to get to the car base to go to a special vehicle for cleaning. We come back to the question “When?” If there are no interruptions, spare generators must be prepared – they must have fuel. If there are not enough employees, they must be hired and trained. When was the last substation inspected? When does the warranty expire? When does the repair end after the warranty expires, which is determined by the availability of spare parts for this model? When was the last staff training? When does the expected service life end?

Why?

Why doesn’t this happen elsewhere? In addition to purely natural factors or geographical location, you can think of poles where wires hang. What are they – wood, iron, reinforced concrete? How long do they last? How long has it been since the installation? Are mains load tests performed in this place in the same way as the heating system is under pressure? The essence of the pressing process is to supply excessive pressure to the system to determine the location of the leak, based on the principle where it is thin – there it breaks. It is better to repair the system in summer than in winter, when the heating system cools down quickly, which can have serious consequences. This is also the case with power stations – earlier in the autumn, when air conditioners and refrigerators are no longer used so much, it is easier to carry out tests, and not in winter, when some households can only be heated by electricity. Fracture is often caused by a tree falling on the wires. Yes, two trees fell on power lines connecting Switzerland and Italy in 2003. caused a system overvoltage and began block-by-block outages that shut down the entire country. This means that if you cut down trees next to power lines in the city on time or clean forest clearings under power lines, it can also reduce the risks.

How?

How to avoid or prevent it? Not many schools know that since the 1950s, science has evolved to study the laws of technical equipment and construction failure. This is called reliability theory. Moreover, the word ‘reliability’ has a purely mathematical definition. “Reliability” is an integral function of the probability of failure-free operation from start-up to the first failure. Redundancies and self-monitoring are used to increase system reliability. The mean time between failures (MTBF) is calculated. It indicates the average operating time of a device or system component between failures. To significantly reduce the risk, it is possible to replace the component before it expires or at least replace the spare part in the immediate vicinity. At the server hardware controller level, you have already been taught how to calculate the probability of a hard disk failure. The controller offers to replace the hard drive’s hard drive before it fails to recover information from healthy disks on the fly, even without shutting down the server.

WHO?

Often, the human factor or human error is a weak link that also requires control. Joke: “If something can go wrong, it goes wrong,” also known as Murphy’s Law. Edward A. Murphy was an engineer at NASA’s JPL Research Center. Evaluating the work of technicians in one laboratory, he said that if you can do something wrong, these technicians will do just that. According to legend, the phrase (“If there are two ways to do something and one of them leads to disaster, someone chooses that path”) was first said at the moment when a running aircraft engine started to rotate the propeller in the wrong direction. As it turned out, the technicians installed the parts upside down. Today, automation systems often make decisions independently and only inform the person. But imagine that in the event of an accident, the warning system cannot inform the dispatcher? Who else should the system inform? Who should check if the system works? Also the question “Who?” related to intentional damage to property. The risk of vandalism or terrorism must be taken into account.

Group game “Prevent power outages”

Select the cause and possible consequences. In addition to the case described above, a storm wind, the reasons may be:

1. Lightning strike (“Night of Fear in New York”, 25 hours 9 million residents were not powered, USA, 1977)
2. Personnel error (Chernobyl nuclear power plant, USSR, 1986)
3. Geomagnetic storm (on a frosty winter night, the entire province of Quebec was left without power for 9 hours, Canada, 1989)
4. Hurricane (Hurricane Katrina in the United States left more than 2 million people without electricity, 2005)
5. Rising consumption (Germany, France, Belgium, Italy, Spain, 2006) cut off millions of electricity without electricity
6. Equipment deterioration (metal fatigue. Accident at Sayano-Shushenskaya HPP, Russia, 2009)
7. Earthquake (Japan Fukushima-1 nuclear power plant accident, 2011)
8. Storm and flood (no electricity but 12,500 houses (Pärnu, Estonia 2018)
9. Cyber attack on energy management systems (HPP “Guri” Venezuela 2019)
10. Cold rain and wire icing
11. Fire at Jõgeva substation left almost 8,000 customers without electricity (Estonia, 2021)
12. Error in AI-based program that manages loads and energy distribution (hasn’t happened yet)

Divide the class into 6 groups according to the questions: “what?”, “Where?”, “When?”, “Why?”, “How?”, “Who?” Determine the situation with a possible accident. Ask these groups to discuss the answers to these questions and to summarize measures to avoid them. The task is given 12 minutes, after which each group representative gives everyone the answers to their group’s question. Finally, you can ask homework to create guidelines for answering options that are not for your group.

For example, group members with the question “What?” I answer the question “Who?” and vice versa. This increases interest in the responses of other groups. In order to maintain interest, it is important to announce which question the group is answering after everyone has spoken. For those who are not actively involved in the debate, there may be an individual task: what to do during a power outage?

PS The most up-to-date information on Estonian power problems is available on the power grid status card Elektrilevi … Elektrilevi notifies the owners of the emergency shutdown by SMS. If you have not received an SMS within 10-15 minutes after the power failure, report the power failure by calling 1343.