CERN Safety Rule Definitions (Safety Glossary)

The definitions below are those given in CERN Safety rules.

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                                                          Definition          Domain Origin
A practice  It's an human activity that can increase the exposure of individuals to radiation from an artificial source, or from a natural radiation source where natural radionuclides are processed for their radioactive properties. Radiation Protection  F
Accelerator A material that, when mixed with a catalyst or a resin, speeds up the chemical reaction between the catalyst and the resin. Also called a promoter. Radiation protection, Fire IS-41
Accident Event occurring on the CERN site, or offsite in the course of official activities for CERN, and resulting in bodily injuries, having consequences on the environment, or causing significant damage to property belonging to CERN or third parties. This includes road accidents on the CERN site. Incident A2
Accreditation - authorized person Recognition by the employer to the capacity of a person under their authority to perform security vis-à-vis the electrical hazard tasks entrusted. Electrical and electromagnetic  
Accredited body A body accredited by a national authority of a CERN member state or by CERN. In the context of this Safety Regulation, an accredited body is a body qualified in the sampling and analysis of the hazardous chemical agent involved in a given CERN activity. Chemical SR-C
Activity involving hazardous chemical agents
Any activity involving or potentially involving the use of hazardous chemical agents including the purchase, storage, handling, transport and disposal of hazardous chemical agents.
Chemical SR-C
Alarm sensor Device designed to put the system in the alarm state when an abnormal event indicating the presence of danger is detected. Emergency IS-37
Ambient dose It's an operational quantity used in monitoring of ambient external radiation. It serves as an estimate for the (not measurable) limiting quantity effective dose. Radiation Protection F
Antioxidant A substance that, when added in small quantities to the resin during mixing, prevents its oxidative degradation and contributes to the maintenance of its properties. Radiation protection, Fire IS-41
Biological limit value Limit of the concentration in the appropriate biological medium of the relevant agent, its metabolite, or an indicator of effect on the state of health of a person related to exposure to specific hazardous chemical agents at work. Chemical SR-C
Carcinogen A substance or mixture which meets the criteria for classification as a “hazard category 1A or 1B carcinogen” according to Regulation (EC) 1272/2008; or a substance or mixture or process referred to in Annex I of Directive 2004/37/EC as well as a substance or mixture released by a process referred to in Annex I of Directive 2004/37/EC. Chemical SR-C
Catalyst A substance that changes the rate of a chemical reaction without itself undergoing permanent change in composition or becoming a part of the molecular structure of the product. A substance that speeds up the cure rate of a compound when added in minor quantity, compared to the amounts of primary reactants (see also accelerator and hardener). Radiation protection, Fire IS-41
Chemical agent Any chemical element or compound, on its own or admixed, as it occurs in a natural state or as produced, used or released, including release as waste, by any activity whether or not produced intentionally. Chemical SR-C
Co-activity Work performed simultaneously at the same worksite by workers employed by different employers. Worksite IS-50
Combustion The exothermic reaction of a substance with an oxidizer (in most cases air) generally accompanied by flames and/or glowing and/or emission of smoke. Radiation protection, Fire IS-41
Component Any item essential to the functioning of equipment and systems. In the context of this General Safety Instruction, a component is an essential item to the safe functioning of equipment and protective systems but with no autonomous function. Chemical GSI-C2
Composite material A combination of two or more materials, reinforcing elements and composite matrix binders, differing in form or composition on a macro scale. The constituents retain their identities, that is they do not dissolve or merge completely into one another although they act in concert. Normally the components can be identified and exhibit an interface between one another. Radiation protection, Fire IS-41
Compulsory medical examination Any medical examination performed during an ordinary check or in the event of any special hazard, which is either stipulated by the Staff Rules and Regulations or an administrative circular, the Rules and Regulations of the CERN Pension Fund and the CERN safety rules, or required by the competent body of the Organization to meet the needs of occupational medicine. Organizational A1
Confined space surpervisor It's a person having direct responsibility for the normal operation of the confined space and who knows intimately the problems concerning the space and its peculiarities for entry. He is also responsible for carrying out the procedures prescribed in this code, unless otherwise specified. Workplace A4
Confined space It's a space with unfavourable ventilation into which occasional entry is made for the purposes of maintenance, repair and/or cleaning and with a volume such that dangerous air contamination cannot be prevented or removed by ventilation through the openings in the enclosure. It also includes spaces where the openings are so remote or small that difficulties arise for entering or for the removal of a worker who is suddenly overcome.
Examples of confined spaces include: tanks, cylinders, ovens, pressure and vacuum vessels, boilers, pits, wells, sewers and degreasers, as well as physics equipment such as Cherenkov counters and the interiors of large experiments such as those installed at LEP and proposed for LHC.
Workplace A4
Consignation Procedure to protect people and structures or installations against the effects of any accidental or maintenance of any occurrence or reoccurrence of unwanted stress on the structure or installation. Electrical and electromagnetic  
Cross linking With thermosetting and certain thermoplastic plastics, the setting up of chemical links between the molecular chains. When extensive, as in most thermosetting plastics, cross linking makes an infusible supermolecule of all the chains. In rubbers the cross linking is just enough to join all the molecules into a network. Radiation protection, Fire IS-41
Cryogenic equipment/accessories
All components of an installation operating at temperatures below 123.15 K.
Mechanical GSI-M2
Cryogenic facility An installation where cryogenic fluids are produced, used or stored. Mechanical IS-47
Cryogenic personnel
Those engaged in or responsible for the production, use, transport, storage and disposal of cryogenic fluids.
Mechanical IS-47
Cryogenic This term refers to substances, the boiling point of which is below -150°C. Mechanical IS-47
Department The CERN Department to which the equipment is assigned. Mechanical SR-M
Ease of ignition The ease with which a material can be ignited under specified test conditions. Radiation protection, Fire IS-41
Effective dose
It's the sum of the weighted equivalent doses in the tissues and organs of the body from external and internal irradiation. The dose limit is given in terms of effective dose.
Radiation Protection F
Elastomer A generic term for all substances having the properties of natural, reclaimed, vulcanized or synthetic rubber, in that they stretch under tension, have a high tensile strength, retract rapidly, and recover their original dimensions fully. Typical elastomers contain long polymer chains. Fire, Radiation protection IS-41
Electrical equipment Equipment used in the production, processing, transportation, distribution or use of electrical energy, such as machine, transformer, switchgear, measuring equipment, safety devices, electrical conduit, equipment use. Electrical and electromagnetic C1
Electrical installation All electrical equipment associated with specific coordinates for a given application. Electrical and electromagnetic C1
Engineering controls Controls that isolate or remove the hazard from the workplace. Chemical SR-C
Equivalent dose It's defined as the absorbed dose in a tissue or organ weighted for the type and energy of the radiation. Radiation Protection F
Explosive atmosphere (ATEX) A mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapours, mists or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture. Chemical GSI-C2
Fail-safe Automatic protection mechanism designed to ensure safety even when the failure of a piece of software or hardware is detected in the system. Emergency IS-37
False alarm An alarm triggered accidentally in the absence of any danger. Emergency IS-37
Filler A relatively inert substance added to a plastic to alter its physical, mechanical, thermal, electrical or other properties, or to lower cost or change density. Usually means a particulate additive. Radiation protection, Fire IS-41
Fire performance The physical and/or chemical changes that take place when a material, product and/or structure is exposed to an uncontrolled fire. Radiation protection, Fire IS-41
Fire resistance Ability to contain fire, heat and smoke into a compartment and to maintain mechanical stability. Fire NS-29
Fire retardant A substance added, or a treatment applied to a material in order to suppress, significantly reduce, or delay the combustion of the material. Radiation protection, Fire IS-41
First work category Work performed by employees of external contractors, together with or without Members of the Personnel, for a project (excluding service work), on the same worksite and where the volume of work exceeds 500 person-days. Worksite IS-50
Flammability The ability of a material or product to burn with flame under specified test conditions. Radiation protection, Fire IS-41
Flammable substances
- liquid substances and preparations having a flash point less than or equal to 55°C, or
- solid substances and preparations which may readily catch fire after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source of ignition, or
- gaseous substances and preparations which are flammable in contact with air at ambient temperature and pressure, or
- substances and preparations which, in contact with water or damp air, evolve extremely flammable gases in dangerous quantities, at a minimum rate of 1 litre per kilogram per hour, or
- substances that are spontaneously flammable in air, or
- substances and preparations which may become hot and finally catch fire in contact with air at ambient temperature without any input of energy, or
- other substances which are not readily combustible or flammable under normal conditions, but which are explosive if the particle size is particularly small or the ignition energy is particularly high.
Chemical GSI-C2
Fume/Smoke A visible suspension of solid and/or liquid particles in gases resulting from combustion or pyrolysis. Radiation protection, Fire IS-41
Functional safety Functional safety constitutes a guide for the development of safety systems. Industrial systems need to operate with an increasingly high degree of reliability, availability, maintainability, and Safety. This is the subject of IEC standard 61508, whose aim is to ensure functional safety, i.e. reduce risk to an acceptable level. This standard has already been taken into account in the petrochemical field and very similar standards have been applied in the nuclear and aeronautical fields. Emergency IS-37
Glow combustion Combustion of a material in the solid phase without flame but with emission of light from the combustion zone. Radiation protection, Fire IS-41
Group leader in Matters of Safety (GLIMOS) In experimental Collaborations, the person responsible for all Safety matters is the "Group Leader in Matters of Safety" or GLIMOS, who is appointed by the Leader of the Host Division on the proposal of the Collaboration spokesman. A full list of his duties and means available is given in Section 8 of annex 2.1 of the document "Safety Policy at CERN", SAPOCO 42, Revision 1994. Chemical G
Group technically in charge Group that carries out the installation, maintenance, disabling, and recommissioning of a level-3 alarm system. If more than one group is involved, they must define which of them is responsible within the meaning of the provisions of this Safety Instruction. Emergency IS-37
Halogen A halogen is a member of the Group VII A of the periodic table of chemical elements which contains fluorine, chlorine, bromine and iodine. Radiation protection, Fire IS-41
Hardener A substance or mixture added to a plastic composition to promote or control the curing action by taking part in it. Radiation protection, Fire IS-41
Hazardous area An area in which special precautions are necessary to protect the occupational health and Safety of persons. In the context of this General Safety Instruction, a hazardous area is an area in which an explosive atmosphere may occur. Chemical GSI-C2
Hazardous chemical agent
-(i) any chemical agent which meets the criteria for classification as a dangerous substance or mixture according to the criteria set out in Regulation (EC) 1272/2008,
-(ii) any chemical agent which, whilst not meeting the criteria for classification as a dangerous substance or mixture in accordance with (i), may, because of its physico-chemical, chemical or toxicological properties and the way it is used or is present in the workplace, present a risk to the safety or health of the person, including any chemical agent to which an occupational exposure limit value is assigned.
Chemical SR-C
Heat release raye The calorific energy released per unit time by a material during combustion under specified test conditions. Radiation protection, Fire IS-41
HSE Unit Organic unit competent in matters of occupational health and safety and environmental protection. General  
Independence Two systems are said to be independent when they have the same objectives but different functions and means. Emergency IS-37
Insulating core (sandwich) panel Composite panel, realized by means of a lightweight inner core sandwiched between and bonded to facing sheets, e.g. galvanized steel. Insulating core (sandwich) panels are often used for the construction of internal structures inside industrial buildings. Their main use is in providing enclosures that allow control of temperature, humidity, noise, dust particles, etc... Fire NS-29
Intumescent Swelling up. Refers to coatings of paint or mastic which are applied to surfaces and puff or swell up in a fire, thus protecting the underlying material. Radiation protection, Fire IS-41
Issuer The person who requests a level-3 alarm detection system to be disabled and who must be a CERN staff member. Emergency IS-37
Laws Laws, rules, regulations, ordinances, prescriptions, directives, standards and procedures issued by a national or international authority other than CERN or by a professional association or standardization body. General  
Level-3 alarm system Technical installation designed to detect and to inform principally the SCR of a potentially dangerous abnormality. It consists of a detector (or detection system), a transmitter (or transmission system), and a receiver (or reception system). Emergency IS-37
Level-3 alarm Warns of the presence of a potential danger to human life, to property, or to the environment. Emergency IS-37
Lifting accessories Components or equipment not attached to the machine and placed between the machinery and the load or on the load in order to attach it. Equipment which falls in this category is for example: slings, chains, cables, ropes, hooks, rings and lifting beams, including those for moving such loads in a horizontal plane. Mechanical GSI-M1
Lifting equipment Machines, including those moved directly by human strength, the purpose of which is to lift a load not attached in a permanent fashion to the machine. Equipment which falls within this category is for example: jib cranes, overhead travelling cranes, gantry cranes, hoists, pallet trucks, fork‐lift trucks, lifting platforms, winches, jacks. Mechanical GSI-M1
Manipulation It's defined to include production, construction, treatment, mounting, use, storage transport, disposal, importation, export, transit and any form of loan to third parties. Radiation Protection F
Maximum allowable pressure Means the maximum pressure for which the equipment is designed, as specified by the manufacturer. Mechanical GSI-M2
Monomer A single molecule that can react with like or other molecules to form a polymer. The smallest repeating structure of a polymer. Radiation protection, Fire IS-41
Mutagen A substance or mixture which meets the criteria for classification as a “hazard category 1A or 1B mutagen” according to Regulation (EC) 1272/2008. Chemical SR-C
Narcotic Of substances etc. Having the effect of inducing stupor, sleep or insensibility. Radiation protection, Fire IS-41
Near miss Event presenting a significant risk exposure to the occurrence of an accident, even in the absence of injuries and damages. Incident A2
Noise Consists of sounds of different amplitudes and frequencies. Noise A8
Non-standard electrical equipment or installation Electrical equipment or installations not covered by a specific national or international standard. Electrical and electromagnetic C1
Occupational exposure limit value Limit of the time-weighted average of the concentration of a hazardous chemical agent in the air within the breathing zone of the person concerned in relation to a specified reference period. Chemical SR-C
Occupationally exposed person It's a person subject to a potential exposure incurred at work from practices liable to result in doses exceeding the dose limits for member so of the public. Radiation Protection F
Olefin A group of unsaturated hydrocarbons of the general formula CnH2n and named after the corresponding paraffins by the addition of -ene or -ylene to the root (e.g. ethene or ethylene from ethane). Radiation protection, Fire IS-41
Optical density of smoke Measure of the degree of opacity of smoke, usually expressed as the common logarithm of the ratio of the incident light to the transmitted light. Radiation protection, Fire IS-41
Organic unit Department or administratively assimilated unit. General  
Person technically responsible Member of the group technically in charge, who is responsible for all or part of a level-3 alarm system (installation, maintenance, operation). This person is responsible for disabling and recommissioning the system, either personally or via a contractor working under his supervision. Emergency IS-37
Personal Medical File A Medical File opened for members of the personnel listed in Chapter 2.1 of this Code and any person making use of the Medical Service as prescribed by Administrative Circular No. 10 § 3.1 and § 8.4. It contains the results of the medical examinations performed from the time of recruitment to the person’s departure from the Organization, including correspondence with the medical fraternity and the results of additional examinations. The records are kept in the files after departure of the person from the Organization. Organizational A1
Personal Protective Equipment Any device or appliance designed to be worn or held by an individual for protection against one or more health and safety hazards and falling within the scope of Council Directive 89/686/EEC. Chemical SR-C
Plasticizer A material incorporated into a plastic to increase its workability, flexibility or distensibility. Normally used in thermoplastics. Radiation protection, Fire IS-41
A group of organic materials which, though stable in use at ambient temperatures, are plastic at some stage in their manufacture and then can be shaped by the application of heat and/or pressure.
Radiation protection, Fire IS-41
Poloyolefin Plastics based on a polymer made with an olefin as essentially the sole monomer. The most important polyolefins used as standard plastics are low-density polyethylIS41 31ene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP). Less common materials are polybutene (polybutylene) and polymethylpentene. Radiation protection, Fire IS-41
Polymer A member of a series of polymeric compounds. A substance composed of very large molecules, which consist essentially of recurring long-chain structural units, which distinguish polymers from other types of organic molecules and confer on them tensile strength, deformability, elasticity and hardness. Radiation protection, Fire IS-41
Pressure equipment Vessels, piping, safety and pressure accessories, not exposed to open flame, and subject to a maximum allowable pressure greater than 0.5 bar (gauge) and manufactured after 29 May 2002. Where applicable, pressure equipment includes elements attached to pressurized parts, such as flanges, nozzles, couplings, supports, lifting lugs, etc. Mechanical GSI-M2
Project Leader The person responsible for the design, execution, or supervision of the execution, of project work or service work, and acting on behalf of the Leading department; the work supervisor or the CERN member of personnel in charge of the contract falls under this definition. Worksite IS-50
Project work Work to be executed in a predefined time resulting in a new or significantly modified facility, building, installation or equipment. Worksite IS-50
Protected egress path Portion of building (corridors, stairs, rooms) used to evacuate a compartment in fire, protected from smoke by means of walls and doors, and kept free from combustibles. Fire NS-29
Protective systems In the context of this General Safety Instruction, protective systems are devices other than components of the equipment defined above which are intended to halt incipient explosions immediately and/or to limit the effective range of an explosion and which are separately placed on the market for use as autonomous systems (e.g. flame arrestor, pressure release, bursting disc). Chemical GSI-C2
Pyrolysis Irreversible chemical decomposition of a material due to an increase in temperature without oxidation. Radiation protection, Fire IS-41
Qualified person (in electricity) Person with training, knowledge and experience appropriate for electricity to enable him/her to analyze the electrical hazards and avoid these potention hazards. Electrical and electromagnetic  
Questionnaire on occupational hazards A list concerning special occupational hazards is drawn up when the person concerned starts working on the site. This list is made using the questionnaire given in the Annex and it is subsequently updated during compulsory medical examinations. It forms part of the personal medical record. Organizational A1
Radioactive object/material Object which specific activity and total activity are greater than defined exemption limits given in the relevant Safety Instructions or the doser ate at 10 cm from its surface is higher than 0.1 µSv/h, after the subtraction of the dose rate due to local background radiation. Radiation Protection F
Radioactive source It's a radioactive substance manufactured in tentionally for use in practices such as instrument calibration, instrument response testing or experiments, the activity of which exceeds the general authorisation limit defined in the relevant Safety Instruction. Radiation Protection F
Radioactive waste It's defined as radioactive substance or radioactively contaminated materials for which there is no further use. Radiation Protection F
Rate of flame spread Distance travelled by a flame front during its propagation per unit time under specified test conditions. Radiation protection, Fire IS-41
Redundancy Two systems are said to be redundant if they perform the same tasks and provide the same functions. Emergency IS-37
Resin In this document it is taken to mean the viscous liquid that can be cross-linked into its final solid form by means of a chemical reaction with a variety of catalysts, hardeners and accelerators, with or without heat. Radiation protection, Fire IS-41
Safety Coordinator The person entrusted by the Leading department with performing the duties referred to in chapter 5. Worksite IS-50
Safety data sheet Safety data sheet within the meaning of Commission Regulation (EU) 453/2010. Chemical SR-C
Safety integrity (RAMS) of a system (Reliability, Availability, Maintainability, and Safety) The safety integrity (RAMS) of a system is the probability of a safety-related system operating satisfactorily under a defined set of conditions for a defined period of time. Emergency IS-37
Safety Integrity Level SIL Discrete level (SIL 1, 2, 3 or 4) categorizing the safety integrity of E/E/PE systems, with technology based on electric, electronic and/or programmable electronic methods,
SIL4 denoting the highest level of integrity.
Emergency IS-37
Sandwich panel structures The whole assembly consisting of the sandwich panels, supporting frames and fixing devices. Fire NS-29
Second work category All other work, which does not fall under the first category. Worksite IS-50
Service work Work to be executed continuously on an existing facility, installation or equipment and not resulting in a new one. Worksite IS-50
Simple pressure vessel Any welded vessel subjected to an internal maximum allowable pressure greater than 0.5 bar (gauge) which is intended to contain air or nitrogen and which is not intended to be fired and manufactured after 1 July 1990. Mechanical GSI-M2
Smouldering The slow combustion of a material without light being visible and generally evidenced by an increase in temperature and/or smoke. Radiation protection, Fire IS-41
Special equipment
- mechanical equipment not falling within the scope of European Directives;
- mechanical equipment which, due to its designated function, cannot comply with European Directives;
- metallic structures not falling within the scope of Eurocodes;
standard mechanical equipment classified by the Department as e quipment of high Safety relevance;
Mechanical SR-M
Special mechanical equipment (GSI)
- mechanical equipment not falling within the scope of the applicable European Directives;
- mechanical equipment which, due to its designated function, cannot comply with European Directives;
- metallic structures not falling within the scope of Eurocodes;
- standard mechanical equipment classified by the Department as e quipment of high Safety relevance.
Mechanical GSI-M3
Special mechanical equipment (Guideline)
- high potential hazard for people, environment or for other installations in case of failure;
- high complexity of the design, or reduced design safety factors;
- unconventional materials or fabrication technologies;
- Special operating conditions (loading, t emperature, etc.).
Mechanical GSI-M3
Stabilizers Chemicals used in plastic formulations to help maintain physical and chemical properties during processing or service life. For instance an ultraviolet stabilizer is designed to absorb ultraviolet rays and prevent them from attacking the plastic. Radiation protection, Fire IS-41
Standard equipment
(i) mechanical equipment, not considered of high Safety relevance, falling within the scope of the applicable European Directives and which, due to its designated function, can comply with them;
(ii) metallic structures falling within the scope and compliant with the applicable Eurocodes;
Mechanical SR-M
Standard lifting equipment Means lifting equipment, not considered of high Safety relevance, falling within the scope of the European Directives mentioned in § 1.3 and which, due to its designated function, can comply with the above mentioned Directive. Mechanical GSI-M1
Standard pressure equipment Pressure equipment, simple pressure vessels and transportable pressure equipment including cryogenic equipment, not considered of high Safety relevance, falling within the scope of the European Directives mentioned in § 1.3 and which, due to its designated function, can comply with the above mentioned Directive. Mechanical GSI-M2
Territorial Safety Officer (TSO) Territorial Safety Officers are appointed by the Division Leader who is primarily responsible for the area to be covered, with the agreement of any other Divisions involved. They are accountable to the Divisional Safety Officer of their Division in the first instance, but may also have delegations of authority from Safety Officers in other Divisions, to whom they are then correspondingly accountable. A full list of their duties and means available is given in Section 5 of annex 2.1 of the document "Safety Policy at CERN", SAPOCO 42, Revision 1994. Chemical G
Thermoplastics A class of plastic materials that is capable of being repeatedly softened by heating and hardened by cooling. ABS, PVC, polystyrene, polyethylene and polypropylene are all thermoplastic materials. Radiation protection, Fire IS-41
Thermosetting plastics A class of plastic materials that will undergo a chemical reaction by the application of heat, pressure, catalysts etc., leading to a relatively infusible, non-reversible state.
Phenolics and epoxies are typical thermosetting plastics.
Radiation protection, Fire IS-41
Toxic to Reproduction substance A substance or mixture which meets the criteria for classification as a “hazard category 1A or 1B toxic to reproduction substance” according to Regulation (EC) 1272/2008. Chemical SR-C
Transportable pressure equipment All receptacles and tanks used for the transport of certain gases and dangerous substances as defined in the European Directive 99/36/EC and manufactured after 1 July 2001. Mechanical GSI-M2
Voluntary medical consultation A medical consultation or examination that may be performed at the request of a member of the personnel, whether or not linked to work, on the understanding that,
except in emergencies, CERN’s occupational medical officers are not authorized to administer medical treatment.
Organizational A1
Work equipment In the context of this General Safety Instruction, work equipment is equipment, protective system, components or any associated connecting devices. Chemical GSI-C2
Young person Any person under 18 years of age. Chemical SR-C


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