Risks assessment in terms of OHS for critical power infrastructures in context of industrial safety

The aim of occupational health and safety in the context of industrial safety is to provide the national industry with a proper operation state, an ergonomic, optimal and healthy work environment, safe workers and workplaces, safety of industrial processes, to limit and mitigate any unforeseen situation generated by events which might negatively affect the occupational health and safety level. The current paper approaches the risk assessment in terms of occupational health and safety within a cross-border 400/220 kV power substation interconnected to the European power grid, identified and assigned as European critical infrastructure. The assessment is carried out using the INCDPM Bucharest method, in order to establish the risk/safety levels in a quantitative manner, based on a systemic analysis and on the assessment of risks of accidents and professional diseases. The application of the method ends in a workplace assessment sheet which comprises the global risk level of the power substation and which sets the grounds for the plan for preventing accidents and professional diseases within the analysed power substation. 1 Description of the INCDPM Bucharest method for risk assessment in terms of OHS The method developed by National Research and Development Institute of Occupational Safety "Alexandru Darabont" – INCDPM Bucharest, aims to determine the quantitative level of risk/safety for a workplace, sector, section or company, based on a systemic analysis and assessment of risks of injury and occupational disease, in terms of Occupational Health and Safety – OHS. The application of the method is finalised with a summary document – Assessment Sheet of Workplace, which includes the global risk level of the workplace. The developed assessment sheet of the workplace is the basis of the program for the prevention of accidents and occupational diseases for the workplace, sector, section or company analysis. The essence of the method is to identify all risk factors in the system analysis (workplace) on the basis of pre-established control lists and to quantify the risk dimension on the basis of the combination of the severity and frequency of the maximum foreseeable consequence. The level of security for a workplace shall be inversely * Corresponding author: pdragos_74@yahoo.com © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). MATEC Web of Conferences 343, 10020 (2021) https://doi.org/10.1051/matecconf/202134310020 MSE 2021


Description of the INCDPM Bucharest method for risk assessment in terms of OHS
The method developed by National Research and Development Institute of Occupational Safety "Alexandru Darabont" -INCDPM Bucharest, aims to determine the quantitative level of risk/safety for a workplace, sector, section or company, based on a systemic analysis and assessment of risks of injury and occupational disease, in terms of Occupational Health and Safety -OHS. The application of the method is finalised with a summary document -Assessment Sheet of Workplace, which includes the global risk level of the workplace. The developed assessment sheet of the workplace is the basis of the program for the prevention of accidents and occupational diseases for the workplace, sector, section or company analysis. The essence of the method is to identify all risk factors in the system analysis (workplace) on the basis of pre-established control lists and to quantify the risk dimension on the basis of the combination of the severity and frequency of the maximum foreseeable consequence. The level of security for a workplace shall be inversely proportional to the level of risk. The method comprises the following mandatory steps [1,2,8,9]: 1) The definition of the system to be analysis (workplace); 2) The identification of risk factors from the system; 3) Assessment of risks of injury and occupational disease; 4) Risk prioritization and prevention priorities; 5) Proposal for prevention measures.
Working tools: 1) List for identifying risk factors (performer, work environment, work load, means of production); 2) List of possible consequences of the action of risk factors on the human body (possible consequences, location of consequences); 3) Quotation scale of severity and probability of consequences (severity class/consequences -severity of consequences, classes of probability/eventsprobability of consequences); 4) Risk assessment scale (severity class, probability class); 5) Scale for the assignment of risk levels, respectively safety levels (levels of risksafety levels); 6) Workplace assessment sheet -summary document (general information, actual assessment); 7) Proposed measures sheet (record-keeping and follow-up of proposed measures).
The global risk level (Nr) per workplace shall be calculated as a weighted average of the risk levels established for the identified risk factors. In order for the result obtained to reflect as accurately as possible the reality, the risk factor ranking, which is equal to the level of risk, shall be used as a weighting element. In this way, the highest risk factor will also be the highest ranking. Thus, it is eliminated the possibility for the cross-compensation effect, involved by any statistical average, to mask the presence of the highest-risk factor.
The formula for calculating the global risk level is the following:  (1) where: Nr -the level of global risk in the workplace; ri -risk factor ranking "i"; Ri -level of risk for the risk factor "i"; n -number of risk factors identified at the workplace. The level of security (Ns) at workplace is identified on the risk/security level mapping scale, built on the opposite proportionality of risk and security levels. Both the global risk level and the safety level are recorded in the workplace sheet. In the case of macro-systems assessment (sector, section, company), the weighted mean of the average safety levels determined for each workplace analysed in the macro-system component (similar workplace are considered as a single workplace) has to be calculated so that to obtain the global level of safety at work for the workshop/section/sector or enterprise under investigation -Ns: (2) where: rp -the workplace ranking "p" (equal to the risk level of the workplace); n -number of workplaces analysed; Nsp -average workplace safety level "p".

The aim of critical power infrastructures in context of industrial safety
For the purpose of industrial safety and societal security, the state must provide a series of facilities for people and companies, such as: access to drinking water and sewage, various fuels, natural gas, electricity, heat, resources, raw materials, etc., so that the economic development to be in continuous progress and in a secure environment. These very important facilities are provided by certain infrastructures, which fall into three main categories [3, 10]: normal infrastructures -a framework structure that ensures the construction and operation of a system; special infrastructures -with a consistent role in the operation of systems and processes and a high degree of stability and security in all the mechanisms of economic and social life of regional interest; critical infrastructures -are usually determinants of the instability, security and safety of systems and processes, with an important role in the development of economic-social, political and military processes. The vulnerability of these infrastructures generates a number of risks and threats to them, thereby endangering industry and societal life, creating dysfunctionalities and causing extreme damage to the economy and society. Critical infrastructure is thus becoming indispensable for industry and society, without which the state and its mechanisms cannot operate and ensure industrial safety and societal well-being, and their protection and/or security becomes a major national and European objective, prompting the representatives of the member states of the EU to take action towards the identification, management and assessment of any risk or threat that could jeopardize the well-being of European citizens. Disruption or destruction of a critical infrastructure may have the following consequences on national and European security: societal insecurity -population affected by lack of facilities; industrial insecurity -industrial entities affected by the lack of facilities and stagnation of production; economic insecurity -economic loss; medical insecurity -population affected by a lack of public health care system; ecological insecurity -loss or destruction of the environment, etc. As the whole industry-economic environment depends on the facilities of the critical energy infrastructures (ultra-high-voltage and very high-voltage power substations and overhead lines -OHL), it makes the issue of which it is highly relevant and topical because the non-supply of electricity to industrial and domestic consumers generates national crises and societal imbalances with extreme effects on national security, the vulnerability of the final consumer and the safety of the citizen. In this context, the National Power Grid becomes a strategic objective of national and European importance, by being a generator of critical infrastructure and ensuring the health and safety at work for power substations staff (operation, maintenance or dispatching personnel), it is becoming an objective to ensure continuity of electricity processes and energy security. Each power substation listed as a national or European critical infrastructure (cross-border power substation) can generate risks which can jeopardize the safety of the workers through accidents or occupational diseases, therefore, the assessment of occupational health and safety risks has to become a major objective of every power critical infrastructure and must be carried out by highly skilled energy process specialists and specialists or experts in assessing occupational health and safety risks, in the context of securing the workplace and personnel [4,13,18].

The novelty of the study
OHS Management in terms of very high voltage installations (400 kV) for every power substation listed as critical infrastructure, is a very large area of inter-disciplinarity and multidisciplinarity in the fields of electrical, medical, intelligence and safety, due to the multitude of sources of risks and threats to personnel, with the purpose of finding the most appropriate methods and means of preventing and protecting and ensuring the functionality of workplaces in complete safety, without disrupting the good functioning of national industry and economy.
The most effective way of protecting OHS for personnel from power substation is to eliminate electrical sources of danger, which is an action whose effects are maximum if it is carried out during the design and construction phase of work systems, but which is also beneficial thereafter, provided that a methodology is in place to analyze, identify and determine how to deal with these sources of danger and risk-related personnel.
Since OHS is a major problem for society with regard to national security and the wellbeing of the population, the authors come up with a proposal (novelty): every power substation listed as national or European critical infrastructure, built as a new objective, new or non-refurbished, must be assessed in terms of OHS at least twice a year or whenever the situation requires it (changes in operating systems and schemes or working conditions), with the active and pragmatic involvement of the Romanian state, in order to avoid, prevent and combat possible risks and threats to personnel and work places.
Finally, the role of OHS is to ensure that national industry is in a good working condition, an ergonomic, optimal and healthy working environment, secure personnel and work places, the safety and security of industrial processes, for the purpose of a smooth functioning of the national economy [5,11,17].

Program for assessing conformity with legal and other provisions in force
Within the 400/220 kV power substation exist the followings workplaces [6, 7, 12 ,14]

Risk level assessment for the activity: 400 kV and 220 kV Operational Service
The object of the activity is the operational service of the power installations: -supervision; -control; -maneuver.

Risk factors specific to the means of production:
mechanical risk (falling from the same level, slipping or tripping, explosions of equipment with a lifetime exceeded, falling from a height); electrical risk (direct contact with electrical installations); -thermal risk (burns due to electric arc).

Work load:
According to the operating regulations, the duties of the operational staff are as follows: -performing the handover-receiving operations of the work team; -supervision activity; -control activity; -the activity of executing the electric maneuvers.

Risk factors specific to the work load:
-psychic stress in the 400 kV and 220 kV power substations, when installing short circuits by hand.

Performer:
The following staff works in the power substation: -manager (s) of the power substations (electrical engineer); -shift leaders; -shift leaders aides.

Risk factors specific to the performer:
wrong action: • incorrect identification of the installation and non-verification of the lack of voltage, when mounting the short circuits; • failure to respect the neighbouring distances with risk of electric shock by direct contact; • not checking the lack of voltage before mounting the mobile short circuits. omissions: • omissions of operations during manoeuvres, with risk of burns caused by electric arc, when closing grounding knives or mounting the mobile short circuits without checking the lack of voltage; • non-use and/or non-verification of the personal protective equipment provided and/or of the electrical insulating means and devices.

Work environment:
The operating staff carries out the activity in the control room at the external power substations of 400 kV and 220 kV, where the specific nature of the work assignment requires operation and control activities regardless of climatic conditions and as a result the main risk factor specific to the working environment is the air temperature by exposure to high or low temperatures during the performances of the work assignment [15].

Risk factors specific to the work environment:
physical risk factors: • exposure to adverse weather conditions (low/high temperatures, rain, snow, air currents) during installations' control.  Not checking the lack of voltage before mounting the mobile short circuits 4

Risk level assessment for activity: 20 kV Operational Service
The object of the activity is the operational service of the power installations: supervision; control; maneuver.

Risk factors specific to the means of production:
mechanical risk (falling from the same level, slipping or tripping, explosions of equipment with exceeded lifetime, falling from a height); electrical risk (direct contact with electrical installations); thermal risk (burns due to electric arc).

Work load:
According to the operating regulations, the duties of the operational staff are as follows: performing the handover-receiving operations of the work team; supervision activity; control activity; the activity of executing the electric maneuvers.

Risk factors specific to the work load:
psychic stress in the 20 kV power substations, when installing short circuits by hand.

Performer:
The following staff works in the power substation: -manager (s) power substations (electrical engineer) -shift leaders; -shift leaders aides.

Risk factors specific to the performer:
wrong action: • incorrect identification of the installation and non-verification of the lack of voltage, when mounting the short circuits; • failure to respect the neighbouring distances with risk of electric shock by direct contact; • not checking the lack of voltage before mounting the mobile short circuits. -omissions: • omissions of operations during maneuvers, with risk of burns caused by electric arc, when closing grounding knives or mounting the mobile short circuits without checking the lack of voltage; • non-use and/or non-verification of the personal protective equipment provided and/or of the electrical insulating means and devices.

Work environment:
The operating staff carries out the activity in the control room at the external power substations of 20 kV, where the specific nature of the work assignment requires operation and control activities regardless of climatic conditions and as a result the main risk factor specific to the working environment is the air temperature by exposure to high or low temperatures during the performances of the work assignment [16].

Risk factors specific to the work environment:
physical risk factors: • exposure to adverse weather conditions (low/high temperatures, rain, snow, air currents) during installations' control.

Risk factors specific to the means of production:
mechanical risk factors: • hazardous movements; • cutting edges and sharp corners when replacing broken insulators; • explosion of molten metal particles or electric shock to electric welding; • explosions at transformers.

Work load:
Work load of the service and repair team is to:

Risk factors specific to the work load:
failure to properly prepare and/or failure to comply with the required steps in the performance of maintenance activities; failure to comply with measures to ensure the working area; -oversized physical effort when removing the cutting-off switches from the switchgears.

Performer:
The service-repair team the primary equipment is composed of electricians who are led by a master.

Risk factors specific to the performer: -wrong action:
• misidentification of the installations in which work is being carried out; • wrong maneuvers when performing operational tests; • exceeding proximity distances when transporting materials to the work area and during work; • displacement, stationing in hazardous areas outside the working area; • falling from the same level by unbalancing, during the transport of materials within the area of the power substation, -omissions: • non-use of personal protective equipment as provided or use of non-certified personal protective equipment.

Work environment:
Service activity -primary equipment repair is carried out in the external power substation and very rarely in the mechanical room.

Risk factors specific to the work environment: -physical risk factors:
• inhalation of noxious in paint work; • bad weather conditions (high/low temperature, wind).  Starting of work only on the gasis of a work permit specifying all the conditions for securing the work area

Risk level assessment for activity: 20 kV Primary Circuit Maintenance
The purpose of maintenance and repair of primary equipment is the following types of work: servicing primary equipment; -mechanical activities; -welding and painting activity; -masonry repair; -dismantling of appliances.

Risk factors specific to the means of production:
mechanical risk factors: • hazardous movements; • cutting edges and sharp corners when replacing broken insulators; • explosion of molten metal particles or electric shock to electric welding; • explosions at transformers. When assessing the severity and probability of manifestation of these risk factors, the age of 20 kV power substations is also taken into account, an age that amplifies the accidental potential of electrical equipment.

Work load: Work load of the service and repair team is to: -technical revisions (TR) -annually on all equipment in the power substations; -current revisions (RC) -changes in sub-assemblies, replacement of power substation components;
accidental interventions -in the event of faults or failures in primary equipment; -maintenance of auxiliary installations; -maintenance work on the power substation; -changes of lighting fittings.

Risk factors specific to the work load:
failure to properly prepare and/or fail to comply with the required steps in the performance of maintenance activities; failure to comply with measures to ensure the working area; -oversized physical effort when removing the cutting-off switches from the switchgears.

Performer:
The primary service-repair team for equipment is composed of electricians who are led by a master.

Risk factors specific to the performer: -wrong action:
• misidentification of the installations in which work is being carried out; • wrong maneuvers when performing operational tests; • exceeding proximity distances when transporting materials towards the work area and during work; • displacements, stationing in hazardous areas outside the working area; • falling from the same level by unbalancing, during the transport of materials within the area of the power substation. omissions: • non-use of personal protective equipment as provided or use of non-certified personal protective equipment.

Work environment:
Service activity -primary equipment repair is carried out in the external power substation and very rarely in the mechanical room.

Risk factors specific to the work environment:
physical risk factors: • inhalation of noxious during in paint work; • bad weather conditions (high/low temperature, wind).

Risk factors specific to the means of production:
electrical risk: • direct contact (unprotected terminals, unprotected heating elements); • indirect contact (housing, metal parts). -mechanical risk: • functional movements of technical equipments; • displacements under the effect of propulsion. -thermal risk: • flames, explosion of molten metal particles.

Work load: -protection checks:
• during the revisions, all the verifications provided by the technical books of protection are performed • the monitoring of the protection system parameters is done from the 20 kV control room.

Global risk level assessment of the 400/220 kV power substation
The risk levels, determined for each workplace in the 400/220 kV power substation are generally the followings:

Conclusions
The results of the assessment of risks of industrial injury and illness specific to activities carried out in a 400/220 kV power substation. The assessment of the risks of injury and occupational disease was carried out for five activities that were highlighted at the station: 1) 400 kV and 220 kV Operational Service; 2) 20 kV Operational Service; 3) 400 kV and 220 kV Primary Circuit Maintenance; 4) 20 kV Primary Circuit Maintenance; 5) 20 kV Secondary Circuit Maintenance. and are as follows (table 12). These risk factors must be the focus of those who coordinate the activities of the 400/220 kV power station, as they can always be manifested in an event that can result in human casualties. The conclusion is that those who lead and coordinate the work are not influenced by the global value of the level of risk (which is a weighted average of the risk levels and risk factors identified), but take account of these risk factors with the maximum possible consequence of DEATH for which existing preventive measures must be maintained and the adoption of additional preventive measures. Given the risk factors identified for each assessed activity, specific to the elements of the work system and taking into account the level of risk corresponding to each risk factor, a number of preventive measures have been proposed. After the analysis, it was concluded that the 400/220 kV power substation should enter full retechnologization, for the following reasons: the age of apparatus and equipments in the primary circuits of the 400 kV, 220 kV and 20 kV power substations, -the age of apparatus in the secondary circuits of the 400 kV, 220 kV and 20 kV power substations.
Due to these very old apparatus and equipment, the hazard of incidents is very great, which would endanger the good functioning of the National Power Grid. The risk of injury and occupational disease is particularly high in the 20 kV power substation, which is also a reason for the power substation to go into full retechnologization.