Cause analysis of the hottest industrial accident

Cause analysis of industrial accidents

1 expression about the cause of industrial accidents

during the operation of nuclear power plants, workers will encounter various industrial risks. Once the relevant conditions are met, these risks will lead to industrial accidents such as falling, electric shock, suffocation, chemical burns, poisoning and so on. Although the forms and consequences of accidents are different, the necessary conditions for accidents are often the same. Research shows that in any accident situation, there must be accidental release or improper use of energy and/or toxic substances, and this release is often caused by information errors. Modern safety management scholars put forward the formula of "industrial accident = energy/toxic substances + information error" [1], which concisely summarizes this concept

the following three cases are used to illustrate this formula for understanding

1.1 case 1

in October 1992, the oil pump of No. 1 top shaft of Daya Bay nuclear power station leaked oil and the pump pit was flooded. After troubleshooting, the work preparation personnel are required to use the cleaning agent "jiankelin" (trichloroethane) specified by the equipment supplier to clean the equipment and pump pit. According to the work order, this work is carried out in two steps: the first group is responsible for cleaning the pump and related equipment, and the second group is responsible for cleaning the pit pump with a depth of about 2 m. After cleaning the equipment, the first group of personnel poured the remaining "genklin" into the sewage pipe at the bottom of the pump pit. Then, the second group of personnel cleaning the pump pit began to work with the same cleaning agent at the bottom of the pit. After 15 ~ 20 minutes, the three staff members in this group developed intoxication symptoms of unconsciousness and paralysis. Due to the timely discovery, it did not lead to a serious accident

two facts were found in the investigation of the incident:

(1) there was an English warning posted on the container of "genklin" detergent, which clearly explained the toxicity of the detergent and the safety measures that should be taken when using it. Unfortunately, none of the people who participated in this operation knew English

(2) the work instructions prepared by the work preparation personnel only put forward the technical requirements of the operation, but did not put forward any safety requirements for the use of cleaning agents

if the above formula is used to express the necessary conditions of this event, then:

personnel poisoning = "genklin" (improper use of toxic substances) + information error (the work preparation personnel did not give safety instructions, and the operators could not understand the safety information due to their knowledge level)

1.2 case 2

during the second round of overhaul of Daya Bay unit 2, after the steam inlet pipe of the steam feed pump was removed, the crane personnel could not safely place it in the original planned position of machine room 2. As a result, it was suspended for a long time, which increased the risk of lifting accidents and affected the use and work progress of the crane

the incident investigation found that when planning the placement position and mode of the steam inlet pipe in advance, the work preparation personnel copied the plan for the overhaul of unit 1, but in fact, at the same position as the plant of unit 1, the plant of unit 2 lacked a steel column, and the steel column could not be used to support and fix the steam inlet pipe of the feed pump with asymmetric shape during the overhaul. Finally, special scaffolds had to be built urgently to stabilize them

using the above formula, this event can be expressed as:

inclination of steam inlet pipe = potential energy of heavy objects + information error (the preparation personnel thought that the structure of No. 1 and No. 2 turbine buildings was exactly the same)

1.3 case 3

Figure 1 1eba015va and penetration structure diagram

during the second round of overhaul of No. 1 turbine, The person in charge of the equipment performance test carried out the sealing test on the penetration valve 1eba015va (see Figure 1) of the ventilation system of the reactor building with the "external source license (PR)" [2]. It was found that the valve was not tightly closed during the test, so the person in charge of the test returned the PR license to the isolation Office of the operation Department [3] At the same time, maintenance personnel are required to handle the valve. Both the maintenance supervisor and the person in charge of nuclear island maintenance thought that the person in charge of the test still had a work permit, so they asked the maintenance personnel to work directly on the site. Two operators came to the operation site after obtaining the work order. First, they asked the main control room to give a signal so that the valve could be opened manually on site. After the main control room gives signals as required, one maintenance personnel enters the valve to work, and one person monitors outside the valve. Soon, the operators began to shift, and the new personnel in the main control room released the isolation of the PR ticket that 1eba015va had returned, and remotely closed 1eba015va. As a result, the maintenance personnel were closed in the valve. As the supervisor outside the valve gave an immediate alarm, the operator gave a local opening signal, and the maintenance personnel manually opened the valve on site, so that the personnel inside the valve were not injured

obviously, the cause of the accident can be expressed by the following formula:

accident = energy released by the valve machinery + information error

among them, the information error mainly includes:

(1) the maintenance supervisor and the nuclear island maintenance manager think that the work permit of the person in charge of the test is still valid, and this cognitive error may be caused by improper communication with the person in charge of the test

(2) the maintenance supervisor and the nuclear island maintenance manager mistakenly believe that maintenance personnel can use other people's permits to operate, but in fact, this is not allowed by the system

(3) safety measures are not specified in the work order according to the requirements of the equipment supplier, that is, "the locking device shall be used during the maintenance of the valve to prevent the valve from closing"

(4) after withdrawing the PR permit of the person in charge of the test, the isolation Office of the operation Department did not notify the operator of the main control room in time, so that when the maintenance personnel asked for the valve opening signal, the operator of the main control room thought that the test was still in progress, and according to the procedure requirements after the test, he was obliged to cooperate with the test

2analysis of the causes of industrial accidents

from the above three cases, we can see that the accidental release of energy is related to various information errors

2.1 energy/toxic substances

theoretically, the energy/toxic substances in the above formula are also called inherent hazards, and the existence of inherent hazards is inevitable. For example, the kinetic energy of the high-speed turning lathe, the potential energy stored behind the reservoir dam, the heat energy of steam in the thermal pipe, the chemical substances stored in the container, etc. Once these energy or substances are out of control and accidentally applied to the human body, it will cause personal injury or death

2.2 information error

2.2.1 typical cases of information error

the so-called information error in the formula is also called trigger hazard. If only from the perspective of information reception and users, it includes the following typical situations:

(1) no information

(2) get wrong or incomplete information

(3) did not understand or misunderstood the information obtained

(4) intentionally or unintentionally refuse to accept information

(5) did not respond correctly and timely to the information

most information errors are related to communication behavior, including the way of communication, which means where the fault occurs (formal, informal), the time of communication (timely, not timely), the object or channel of communication (who and who, which department and which department), and the tools of communication (documents, computers, etc.)

2.2.2 cause analysis of information error

The "man machine environment" accident model believes that, generally speaking, as long as the environment is not polluted by substances or the integrity of the inherent energy system is not destroyed, people's actions are the main body of the accident model. If this view is combined with the above formula, it can be considered that the occurrence of industrial accidents is mostly based on information errors. This view is very helpful to evaluate the existing safety management mechanism. For example, This point of view can be used to re recognize the importance of the work permit system (commonly known as the work permit system). In terms of form, work permit is a formal information carrier, a formal way of communication between operators and maintenance or test personnel on a certain operation, and its content and form have been standardized. For this reason, it is protected by the system and concerned by personal consciousness, instead of handling work permits (work tickets), and adopts the so-called "shortcut". If the operator is required to agree to a certain operation without handling work tickets, it belongs to an informal way of communication. The content of this kind of communication is often incomplete, or easy to be misunderstood, and it is also easy to be forgotten, so that the operation is out of control, and the running state of the equipment is out of control, and then accidents occur. There are many such examples in the power industry

take 5 elder brother as an example to further analyze the causes of "information error", which will inevitably lead to a re examination of the existing organizational process, management system and corporate culture. This is because the organizational structure is unreasonable, such as overlapping institutions, too many interfaces, and unclear; Or the management system is imperfect, such as the training and authorization of personnel are inconsistent with their responsibilities, and there is no requirement for risk analysis when preparing the work ticket; Or weak corporate culture, such as lack of team spirit, lack of unified understanding of safety value, lack of prudent work style, etc., will lead to information errors. Obviously, to fundamentally prevent accidents, we must constantly find and solve these management problems

in a word, the formula "accident = energy/toxic substances + information error" tells us that to ensure the integrity of the energy medium system and prevent it from being accidentally applied to the human body and the environment and causing accidents, the key lies in improving the organization's information exchange and communication technically and administratively, and improving the organization's structure, system and culture

note:

[1] this formula can be found in safety in the process industry by Ralph King 1990

[2] "external permit (PR)" is also known as "work permit for using external sources", which is one of the five types of work permits of Daya Bay nuclear power station. If the operation requires the introduction of energy and functional media outside the system, a "foreign source license" must be obtained

[3] the "isolation office" is the place where the operation shift is responsible for handling all kinds of work permits. All work permits are prepared, implemented and issued by the isolation office. After the work is completed, the permit must be returned to the "isolation office" for cancellation procedures, and then the operators implement de isolation and operation settings for the equipment.

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