Regulation of the conditions and procedure for notification of the Nuclear regulatory Agency about events in nuclear facilities and sites with sources of ionising radiation

Article 1. (1) This regulation shall establish the terms and procedure for compulsory notification of the Nuclear Regulatory Agency (NRA) by the licensee or the permit holder about deviations, incidents or accidents, referred to hereafter as “events”, in nuclear facilities and sites with sources of ionising radiation. (2) The regulation shall establish also: 1. The categories of events in nuclear facilities or sites with sources of ionising radiation, subject to the requirement for notification of the Nuclear Regulatory Agency; 2. The requirements to the content and scope of the notifications and event reports, including time limits for their submission to the Nuclear Regulatory Agency; 3. The general requirements to the investigation, analysis and assessment of the events with the purpose of determining the causes of their occurrence and the corrective actions for prevention of their recurrence; 4. The terms and procedure for use and dissemination of the information about events in nuclear facilities and sites with sources of ionising radiation.

Article 2. (1) The licensee or permit holder shall obligatory notify the Nuclear Regulatory Agency within the time limits established by the regulation, about all events, which are classified in one or several of the categories as laid down in Chapter Two. (2) The licensee or permit holder may also notify the Nuclear Regulatory Agency about other events, which are not classified in the categories as laid down in Chapter Two, in case he concludes that such events are of potential significance for the safety of the nuclear facility or the site with sources of ionising radiation.

Article 3. The licensee or permit holder shall establish a system for data collection, registration, investigation, analysis and assessment of the events, which have occurred at the nuclear facility or the site with sources of ionising radiation as well as for determination and implementation of corrective actions for prevention of their recurrence. Chapter Two CATEGORIES OF EVENTS REQUIRING NOTIFICATION OF THE NUCLEAR REGULATORY AGENCY

Article 4. The events in nuclear facilities and sites with sources of ionising radiation, which are subject to notification pursuant to the regulation, shall be classified into the following categories: 1. Deviations from normal operation; 2. Incidents; 3. Accidents.

Article 5. The category of deviations from normal operation (failures, defects, errors, breaches or faults) shall include: 1. Decrease of the power of a nuclear power plant unit by 25 or more per cent compared to the power level immediately preceding the event, which has been caused by system or component failure or defect, or by error or procedure violation by the personnel, and/or by an external influence; 2. Defect or failure of a component, incorrect automatic performance of a system or component, defective or incorrect electrical connection or other causes, e.g. errors 2 or flaws of an operational instruction, which could prevent the execution of a safety function; 3. Actuation of a safety system or a safety system channel, which is not related to execution of safety functions, including triggering of the fire extinguishing system; 4. Failure of a safety system or a safety system channel, which has occurred during a routine check of the system performance; 5. Automatic shut down of a nuclear reactor of a nuclear power plant as a result of failure of systems or components of the nuclear installation and subsequent actuation of the corresponding protection mechanisms; 6. Risk for release of radioactive materials in the environment (atmosphere and hydrosphere) exceeding the limits for radioactive release, established for nuclear facilities (dose quotes); 7. Earthquakes, floods and other natural phenomena or emergency events, such as: explosions, fires, toxic gas releases, registered at the site of the nuclear facility or in close proximity of it, which present a threat to the safety of the nuclear facility and could lead to decrease of the power of the nuclear power plant units or to their shut down; 8. Defects or failures, identified during operation, routine maintenance or inspections of the nuclear facility or the site with sources of ionising radiation, which, if not eliminated, could lead to failure of the nuclear facility in future, or of the structures, systems and components of the site with sources of ionising radiation, deviations from their safe operation, or the release of radioactive materials to the environment; 9. Identification of faults in the system for accounting and control of nuclear material and sources of ionising radiation; 10. Identification of facts, which present a potential threat to the physical protection of the nuclear facility, nuclear material and/or the site with sources of ionising radiation; 11. Natural disasters, operational events and incidents in sites with sources of ionising radiation, which impact: working rooms or storage facilities for radioactive materials; structures, systems and components, containing radioactive materials; means for transportation of radioactive materials, which, in addition, create potential 3 threat of radioactive contamination, uncontrolled release of radioactive materials or exposure of personnel and population to radiation exceeding the established limits; 12. Deviations from the allowed operating mode of a site with sources of ionising radiation, including use of sources by a licensee or permit holder for performing of activities, which are not within the scope of the corresponding license or permit.

Article 6. The following events shall not be considered deviations from the normal operation of a nuclear facility: 1. Decrease of the power of a nuclear power plant unit with the aim of carrying out routine maintenance, as specified in the operating rules of the nuclear installation and in the operating instructions of the systems; 2. Decrease of the power or shut down of the reactor of a nuclear power plant, which has been caused by putting out of operation of systems or components for elimination of defects and failures, on the basis of a request, co-ordinated under defined procedure, not later than twenty four hours before power decrease or power unit shut down (except events leading to excess of the operating limits and conditions); 3. Nuclear power plant unit shut down or power decrease in accordance with the dispatching unit schedule for loading of the power grid in case of actuation of its automatic protection systems or malfunctions in the operation of the grid, as well as if the shut down or power decrease has been specified in the programme for unit start up; 4. Putting out of standby condition some safety systems’ channels, which is not related to elimination of malfunctions of channel components, for a period of time allowed by the operating rules of the corresponding nuclear facility.

Article 7. The category of incidents shall include: 1. Events of the category of deviations from normal operation as laid down in Article 5, if they have become the cause of: 4 a) Failure of a safety system, which has not led to fault of systems or components of the nuclear facility or fault of systems or components of the site with sources of ionising radiation; b) Harm or risk of harm to the health of individuals from the personnel of the nuclear facility or the site with sources of ionising radiation; c) Release of radioactive materials in the rooms or on-site the nuclear facility or the site with sources of ionising radiation, which exceeds the established rates or limits but does not require taking of measures for population protection; d) Contamination with radioactive materials or exposure to ionising radiation of members of the staff exceeding the established limits; 2. Violation of the operating limits and conditions as defined by the operating rules of the nuclear facility or by the operating instructions of the site with sources of ionising radiation, which has resulted in: a) Operating the nuclear facility or the structures, systems and components of the site with sources of ionising radiation in a way, violating the operating limits and conditions; b) The operation of the nuclear power plant unit or the structures, systems and components of the site with sources of ionising radiation being stopped because of reaching or exceeding the limits or because of violation of the operating conditions, as established by the operating rules or the operating instructions; c) Violation of the limit ensuring integrity (leak-tightness) of the cladding of fuel elements or the integrity of the components of the primary circuit of the nuclear power plant unit; 3. Fall and/or damage to a fuel assembly or fuel elements, assembly-shield, neutron absorber or transport container, loaded with fresh (non-irradiated) fuel or with spent nuclear fuel, which has been caused by a failure of a system or component (including loading and lifting equipment, used for handling of nuclear fuel) and/or incorrect personnel action; 4. Fire in a fuel storage facility (fresh or spent nuclear fuel); 5. Failure of a safety system or a safety system channel to fulfil its safety functions, including failure to actuate or initiated but incomplete fulfilment of the safety function, despite the fact that the corresponding parameter is exceeding the safety limit as defined by the operating rules; 5 6. Actuation of an emergency core cooling system, of a localising safety system or of protective devices against exceeding the pressure limit in the primary circuit of the nuclear reactor; 7. Loss of external electric power supply of a nuclear facility, which has led to actuation of the emergency back-up electric power supply; 8. Occurrence of a nuclear-hazardous mode during the process of shutting down of nuclear power plant reactor or refuelling and repair of nuclear installation, including danger of occurrence of unexpected critical mass in reactor core or outside it; 9. Reduction or full loss of the natural circulation of the primary coolant through the reactor core in a shut down state; 10. Foreign objects getting into the reactor primary circuit; 11. Loss, burglary or another uncontrolled (not regulated and allowed) displacement of nuclear material, radioactive substances (including radioactive waste), as well as loss of certificate, providing evidence of the type and activity of the radioactive isotope; 12. Not allowed intrusion of persons in the territory of the nuclear facility or the site with sources of ionising radiation; attempt of crossing of the protective barriers of the system for physical protection of the nuclear facility or the site by persons or vehicles, as well as other events, which present a threat to the physical protection; 13. Harm to the health or death of members of the staff, which has occurred as a result of employment accident in the territory of the nuclear facility or the site with sources of ionising radiation.

Article 8. The category of accidents shall include: 1. Failure of a safety system of a nuclear facility or of a site with sources of ionising radiation, which causes malfunctioning or full loss of a safety function resulting in violation of the design limits for damage of the nuclear fuel and/or of the limits for exposure to ionising radiation of the personnel and population; 2. Serious harm to the health or death of staff members, which has occurred or may happen as a result of exposure to ionising radiation; 6 3. Release of radioactive substances in the environment, which causes exposure of the population equal to the established limits for exposure of the population to ionising radiation, or exceeding these limits, or which requires the implementation of measures for protection of the population. Chapter Three REQUIREMENTS TO THE NOTIFICATION OF THE NUCLEAR REGULATORY AGENCY ABOUT OCCURRENCE OF EVENTS

Article 9. The notification of the Nuclear Regulatory Agency about occurrence of events (deviations, incidents and accidents) shall include: 1. Operative notification about the event (refers only to incidents and accidents); 2. Preliminary written notification about the event; 3. Report about the results of the investigation and the analysis of the event; 4. Additional report about the analysis of the event.

Article 10. (1) The operative notification shall be sent to the Nuclear Regulatory Agency only in case of occurrence of an incident or accident by the shift engineer of the nuclear power plant or by another authorised representative of the licensee or permit holder, by phone, fax, electronic mail (or by other means of communication, which ensures immediate receipt of the information) within a period of one hour after registration of the event. (2) The operative notification shall include: 1. Full name of the nuclear facility and the number of the power unit (for a nuclear power plant) or the name of the site with sources of ionising radiation; 2. Date and time of occurrence and/or registration of the event; 3. Status of the nuclear facility or the site with sources of ionising radiation before the event; 4. Brief description of the event and hypothetical causes; 7 5. Status of the nuclear facility or the site with sources of ionising radiation at the time of sending of the notification; 6. Brief information about the measures undertaken. (3) The operative notification shall be communicated to the chairman of the Nuclear Regulatory Agency or to an official person of the Nuclear Regulatory Agency duly authorised by the chairman. (4) (amended SG No. 46/2007) In case of an incident as per Article 7., which may lead to an accident or may cause a threat of radiological consequences for the population or the environment, as well as in the case of an accident as per Article 8., the operative notification shall be transmitted also to the operative officer on duty of the Directorate General “National Service Civil Protection” and to other bodies of the executive power in accordance with the regulation pursuant to Article 123 of the Act on Safe Use of Nuclear Energy and the internal and external emergency plan.

Article 11. (1) The preliminary written notification about the event shall be sent to the Nuclear Regulatory Agency by a duly authorised official of the licensee or the permit holder by telex, telefax or electronic mail within a period of twenty four hours after the registration of the event or on the first working day after the event, if it has occurred during a holiday. If the telex, telefax or the electronic mail is temporarily not operational, the preliminary written notification shall be transmitted by telephone with a subsequent confirmation by telex, telefax or electronic mail within a period of three days. (2) The format of the preliminary written notification shall be determined by the licensee or permit holder and concerted with the Nuclear Regulatory Agency and shall include as a minimum the following information: 1. Full name and operative indication of the nuclear facility and the number of the power unit (for a nuclear power plant) or the name of the site with sources of ionising radiation; 2. Date and time of occurrence and/or registration of the event; 3. Status of the nuclear facility or the power unit (for a nuclear power plant) or the site with sources of ionising radiation before the event; 8 4. Brief description of the occurrence, the course of the event and the elimination of the consequences of the event; 5. Presumable causes for the event, including a description of violations of the operational limits and conditions (if any); 6. Operative indications of the damaged or failed structures, systems and components, location, type and cause of the damage or failure; 7. Status of the nuclear facility or the corresponding power unit (for a nuclear power plant) or the site with sources of ionising radiation at the time of occurrence of the event; 8. Radiation consequences of the event (if any); 9. Preliminary rating of the event according to the international nuclear event scale (INES). (3) The preliminary written notification shall be sent to the chairman of the Nuclear Regulatory Agency or to a duly authorised by him\her official of the Nuclear Regulatory Agency. (4) (amended SG No. 46/2007) The preliminary written notification about an incident as per

Article 7., which may lead to an accident or cause risk of radiological consequences for the population or the environment, as well as an accident as per Article 8. shall be sent also to the operative official on duty at the Directorate General “National Service Civil Protection”, to the operative centre of the Ministry of Interior and to other bodies of the executive power in accordance with the external emergency plan. (5) After sending the preliminary written notification, if necessary or on request by the Nuclear Regulatory Agency, the licensee or the permit holder is obliged to inform additionally the Nuclear Regulatory Agency about the development of the event and in particular about: 1. Any subsequent reduction of the safety level of the nuclear facility or the site with sources of ionising radiation; 2. Preliminary results from the analysis and investigation of the event; 3. Effectiveness of the corrective measures undertaken; 4. State and/or conditions of the facility or the site, which were not clear at the time of identification and/or registration of the event. 9

Article 12. (1) The report on the results of the investigation and analysis of the event, printed on paper, and all annexes to it, shall be sent by post to the Nuclear Regulatory Agency by a duly authorised official of the licensee or the permit holder not later than one month after the registration of the event. (2) The format of the report on the results of the investigation and analysis of the event shall be determined by the licensee or permit holder and concerted with the Nuclear Regulatory Agency and shall include as a minimum besides the information as laid down in Article 11, Paragraph 2, Items 1 and 2, the following information: 1. Detailed description of the event, which shall include: a) The operational state of the nuclear facility or of the power unit (in case of a nuclear power plant), or of the site with sources of ionising radiation, preceding the event; b) The way of identification and/or registering of the event; c) Description of the chronological sequence of the development of the event, including: the automatic or manual actuation of the safety systems; chronological sequence of the operation of the automatics and the intervention of the operating personnel and their assessment; analysis of the observation of the instructions and procedures; failures and errors in the course of the event development; diagrams and tables, illustrating the changes in the key parameters; 2. Evaluation of the event from safety point of view (safety assessment): a) Consequences of the event, including: exceeding of operational limits and/or operational conditions; release of radioactive substances beyond the established limits in rooms of the nuclear facility or the site with sources of ionising radiation, the site of the facility or the environment; exposure to ionising radiation of members of the staff and of the population; damage and failures of structures, systems and components; b) Analysis of the safety importance of the event – determination of the level of the event according to the international nuclear event scale (INES); c) Influence of the event on the provision of the basic safety functions and on the defence-in- depth (failures of critical safety functions and actions for their restoration, procedures used for control of the accident); d) Potential consequences of the event under different operational circumstances; 10 e) Reference to other similar events, which have occurred earlier at the same nuclear facility or site with sources of ionising radiation; 3. Causes of the event: a) List of the system and component failures and of the errors and violations of the personnel; b) Direct (immediate) causes for system and component failures and for the errors and violations of the personnel; c) Root causes for the system and component failures and for the errors and violations of the personnel; 4. Corrective measures a) Restoring, short-term and long-term corrective measures, including schedule of their implementation, and responsible officials or administrative divisions; b) Measures, aiming at prevention of the recurrence of the event, including measures for prevention of the occurrence of the event under other possible circumstances; 5. List of the annexes to the report on the results of the investigation and analysis of the event.

Article 13. (1) The additional report on the analysis of the event shall be prepared in case the licensee or the permit holder has found important supplementary information about the circumstances, causes and corrective measures, as a result of which a decision for additional investigation and analysis of the event has been accepted. (2) The additional report on the analysis of the event, printed on paper, with all annexes enclosed, shall be sent to the Nuclear Regulatory Agency immediately after its preparation and signing pursuant to the accepted order by the licensee or permit holder. (3) The format of the report on the results of the investigation and the analysis of the event shall be determined by the licensee or permit holder and concerted with the Nuclear Regulatory Agency. (4) In case of an accident as per Article 8. it is permissible to present to the Nuclear Regulatory Agency the root causes for the system and component failures and for the errors and violations of the personnel as part of the additional report on the analysis of the event but not later than four months after the date of the occurrence of the accident. 11 Chapter Four INVESTIGATION, ANALYSIS AND ASSESSMENT OF THE EVENTS

Article 14. (1) The investigation, analysis and assessment of the events in nuclear facilities and sites with sources of ionising radiation shall be carried out according to a procedure and time frames, established by the administrative body of the licensee or permit holder, observing the terms for sending the reports on the results of the investigation and analysis of the events as laid down in the regulation. (2) The licensee or permit holder shall appoint a commission for event investigation and analysis in accordance with the procedure and time frames of paragraph (1). (3) It is mandatory to include inspectors from the Nuclear Regulatory Agency in the commission for investigation and analysis of the event, when the preliminary grading of the safety importance of the event, according to the scale INES, is equal to or greater than level 2. (4) The report on the results of the investigation and analysis of the event shall be sent to the Nuclear Regulatory Agency within the time limit specified by Article 12, paragraph (1). (5) The additional report as per Article 13, paragraph 1 shall be sent to the Nuclear Regulatory Agency observing the time limit specified in Article 13, paragraphs (2) and (4).

Article 15. The licensee or the permit holder shall secure all conditions necessary for the proper operation of the commission for the investigation and analysis of the events, such as: 1. Keeping unchanged the setting and surroundings at the location of the occurrence of the event to the extent, which does not violate the instructions and procedures for actions in case of accidents; 2. Providing the members of the commission with unlimited access to all design materials, operational documents (instructions, procedures, etc.) and to the written evidence collected from the personnel; 3. Submission of all operational data, including diagrams of logging instrumentation, printouts, voice recordings, operation logbooks; 12 4. Performing all necessary calculations, laboratory research, tests and checks, taking photos of structures, systems and components.

Article 16. (1) The commission shall carry out the investigation of the event with the aim of collecting and systemising the information needed to perform successfully the analysis and assessment of the event, to determine its root causes and corrective measures. (2) As a rule, the investigation is directed to the following areas: 1. Determination of the operational states and other conditions before the occurrence of the event; 2. The time sequence (chronology) of the event; 3. Response of the structures, systems and components to the occurrence of the event; 4. Personnel actions at occurrence of the event and in the course of its development; 5. Early symptoms of the event (if any); 6. Response of the licensee or permit holder and undertaking of measures for restoring the normal operational state of the facility; 7. Radiological consequences of the event (if any); 8. Violations of the legislative requirements of the Nuclear Regulatory Agency and of other specialised bodies for monitoring and control as laid down in Article 13 of the Act on the Safe Use of Nuclear Energy; 9. Significance of the event for the safety of the facility. (3) The investigation of the event shall begin as soon as possible in order to ensure that no information has been lost or destroyed and that all evidence is available. The investigation of the event shall not prevent the personnel from performing the actions for achieving a stable state of the facility or the site. (4) Members of the personnel, who have become witnesses or taken part in the event, shall provide written evidence of the event. On the basis of the written evidence, the records in the logbooks and the readings of logging equipment, the commission shall proceed to rendering of the chronological sequence (time-sequence) of the event, which shall be updated on receipt of new data. 13

Article 17. The investigation of the event shall not set as a goal the determination of the guilt of the personnel for faults or violations made, neither it shall give recommendations for administrative measures. The principal aim of the investigation is to determine the facts, related to the occurrence and development of the event, so that the root causes and the corresponding corrective measures for improving the safety of the facility or the site could be specified.

Article 18. The commission shall perform an analysis and assessment of the event with the purpose to determine and evaluate the data and facts, related to the following phases of the analysis: 1. Rendering of the chronological sequence (time-sequence) of the event (what has happened); 2. Determination of the failures and violations (how the event has taken place); 3. Analysis of the causes: a) Direct (immediate) cause (why the event has occurred); b) Root cause (why the event has not been prevented from happening); 4. Assessment of the significance of the event for the safety of the facility (what could have happened); 5. Determination of corrective measures to prevent reoccurrence of the event.

Article 19. (1) In the process of analysis, on the basis of the chronological sequence of the event, the failures, defects, errors and violations shall be determined and those of them to be analysed in depth, shall be selected. For each analysed failure, defect, error or violation the direct causes, as well as the root causes and their contributing factors shall be identified. (2) The analysis of the events, related to the human factor, shall comprise the reasons and circumstances, which have accompanied the occurrence of problems in human behaviour, which, on their part, have facilitated the occurrence and development of the event. The output (result) of the analysis shall be the determination of the areas of human errors and other 14 problems of human behaviour, which can be related to procedures, training, communications, man-machine interaction, management and supervision.

Article 20. (1) On the basis of the root causes for the occurrence of the event, revealed in the course of the analysis, the licensee or permit holder shall determine the corresponding corrective measures. (2) The corrective measures have the purpose of eliminating the root causes for the event and preventing its recurrence. (3) The time limit and the responsibilities for implementation shall be determined for each corrective measure. (4) The licensee or the permit holder shall provide the necessary arrangements for the control and supervision of the implementation of the corrective measures. Chapter Five USE AND DISSEMINATION OF THE INFORMATION ABOUT EVENTS IN NUCLEAR FACILITIES AND SITES WITH SOURCES OF IONISING RADIATION

Article 21. (1) The licensee or the permit holder shall store the information about the deviations, incidents and accidents during the whole period of operation of the nuclear facility or the site with sources of ionising radiation. The information shall include a detailed description of the event, causes, and consequences for the safety and the undertaken corrective measures. (2) The licensee or the permit holder shall establish a system for management of the information on deviations, incidents and accidents, which shall provide the means for easy sorting and processing of the information and retrieval of the data needed. (3) On the basis of the information about deviations, incidents and accidents, as well as on the basis of operational data, the licensee or the permit holder shall perform an analysis of the operational experience, including statistical analysis for evaluation of certain factors for safe operation. The information about failures of structures, systems and components shall be used for updating of the probability safety analysis of the nuclear facility. 15 (4) The indicators for safe operation of the nuclear facility and the methodology of their calculation shall be determined by the licensee or permit holder and concerted with the Nuclear Regulatory Agency. (5) In the course of the analysis of the operational experience, the trends in the personnel behaviour and the operation of the equipment, as well as the trends of various indicators for safe operation shall be determined, and conclusions and recommendations shall be made, for improvement of operation and technical maintenance of the structures, systems and components, as well as for improvement of the preparedness and training of the personnel or for improvement of the management of operational activities of the nuclear facility or the site with sources of ionising radiation.

Article 22. (1) The importance of the events for the nuclear safety and the radiation protection shall be determined on the basis of the international nuclear event scale (the INES scale) of the International Atomic Energy Agency (IAEA) – Vienna. (2) The methodology for determination of the significance of the events for the nuclear safety and the radiation protection (the level according to the INES scale) shall be specified in a guide of the Nuclear Regulatory Agency chairman, which shall be published on the Internet site of the Nuclear Regulatory Agency. (3) The initial level of the event on the INES scale shall be determined by the licensee of permit holder, and the final value of the level on the INES scale shall be determined by the chairman of the Nuclear Regulatory Agency.

Article 23. (1) In accordance with his\her authorities pursuant to Article 5. of the Act on the Safe Use of Nuclear Energy, the chairman of the Nuclear Regulatory Agency shall submit by established rule information about events in the nuclear facilities and the sites with ionising radiation of the Republic of Bulgaria to the specialised international organizations whose member the country is, as well as to state bodies, juridical persons and citizens. 16 (2) The citizens shall be informed about events, incidents and accidents in nuclear facilities or sites with sources of ionising radiation also by the licensee or permit holder on the basis of the INES scale, as follows: 1. About events of level 0 and 1 of the INES scale, when these events may provoke social interest or interest in neighbouring countries – within time limits determined by the licensee or permit holder; 2. About events of level 2 and 3 of the INES scale – not later than 24 hours after the occurrence of the event; 3. About events of level 4 to level 7 of the INES scale – immediately and not later than one hour after the registration of the event. (3) The licensee or the permit holder shall inform the citizens about deviations, incidents and accidents in nuclear facilities or sites with sources of ionising radiation through the media, internet or in any other adequate way. (4) Informing the citizens as laid down in paragraph 2 shall not cancel the obligations of the licensee or the permit holder and the bodies of the executive power to inform the population in the case of accident according to the requirements of the regulation pursuant to Article 123 of the Act on the Safe Use of the Nuclear Energy, the Code for organising of the activities for prevention and liquidation of the consequences of disasters, accidents and catastrophes, as well as in accordance with the internal and external emergency plans. Supplementary Provisions § 1. Within the meaning of this regulation: 1. “External influence ” means the impact of an external event, which is not related to the operation of the nuclear facility or the site with sources of ionising radiation, but could, however, influence its safety. 2. “Personnel error” means a single unintentional wrong actuation of process controls or a single omission of performing the right manipulation; or a single unintentional wrong action during technical maintenance of the structures, systems and components, which are important for safety. 17 3. “Defect” means a failure or deviation from the proper operational mode of a structure, system and component, which has not led, but may lead to loss of its capability to operate. 4. “Operation” means all activities, focused on achieving in a safe manner the goal because of which the nuclear facility or site with sources of ionising radiation has been constructed. In the case of a nuclear power plant it includes the normal working power generating mode of the nuclear reactor, start up and shut down of the reactor, tests, technical maintenance, repair, refuelling, inspections during operation and other related activities. 5. “System channel” is a part of a system, which performs the functions of the system within the scope, determined by the design. 6. “Component” means the equipment, devices, pipelines, cables and other items, which make possible the execution of given functions autonomously or as part of systems, and which are treated as structural units in the reliability and safety analyses. 7. “Beyond design basis accident” means an accident with heavier consequences than the design basis accident, however without substantial damage to the nuclear fuel in the nuclear reactor of a nuclear power plant; as well as the severe accident. 8. “Deviations from the normal operation” means deviations in the operation of the nuclear facility or the site with sources of ionising radiation, which are characterised by exceeding operational limits and conditions of operation. Furthermore the other limits and conditions, defined by the design may also be exceeded, including the safety limits. 9. “Failure” means that a given component is not capable of performing its functions as stipulated by the design or such a deviation in the operation of the structures, systems and components, which is characterised by disruption of their functionality. 10. “Site of a nuclear facility or site with sources of ionising radiation” means the territory within the boundaries of the guarded security perimeter, where the buildings and equipment of the nuclear facility or the site with sources of ionising radiation are located. 11. “Safety limits” means the values of the parameters of the technological process, determined by the design; any deviation from these values can lead to accident. 12. “Operational limits and conditions” means a set of rules, defining the limit values of the parameters, functional capabilities and behaviour of the equipment, systems, components and personnel, which have been approved by a specified procedure with the aim of ensuring safe operation of the nuclear facility or the site with sources of ionising radiation. 18 13. “Design basis accident” means accident conditions against which a nuclear facility or a site with sources of ionising radiation is designed according to established design limits, as well as for the extent of damage of the nuclear fuel or the source of ionising radiation and the release of radioactive substances in the environment. 14. “Design basis” means a set of conditions and events, explicitly accounted for in the design, in accordance with specified criteria, in a manner that the nuclear facility or the site with sources of ionising radiation can withstand them without exceeding certain approved limits with the support of the safety systems. 15. “Working capacity” means the state of the equipment, system or component, when they are capable of executing their design functions. 16. “System” is a set of components intended to perform predetermined functions. 17. “Safety system” means a system important for safety, provided to ensure the safe shutdown of the nuclear reactor in a nuclear power plant, or shutdown of the main technological process in nuclear facility or site with sources of ionising radiation, or residual heat removal from the reactor core, or to limit the consequences of anticipated operational occurrences and design basis accidents. 18. “Structures, systems and components, important for safety” means the safety systems, and also the structures, systems and components for normal operation, failure of which, disrupt the normal operation of the nuclear facility or the site with sources of ionising radiation; or hinder elimination of deviations from normal operation and can lead to design basis accidents or beyond design-basis accidents. 19. “Structures, systems and components for normal operation” means structures, systems and components designed for normal operation of the nuclear facility or the site with sources of ionising radiation. 20. “Severe accident” means an accident, which causes severe damage to the fuel in the nuclear reactor of a nuclear power plant, or damage to a source of ionising radiation, containing radioactive substances, in a site with sources of ionising radiation. 21. “Safety function” means a specific goal to be achieved for ensuring safety. Safety functions include: control of the reactivity or the conditions of the technological process, cooling of the nuclear fuel or the radioactive substances and confinement of the radioactive substances within the preset boundaries. 19 22. “Nuclear-hazardous mode” means an operational mode of the nuclear facility, which can lead to a nuclear accident. Final Provisions § 2. The regulation shall abrogate Regulation No. 2 of the Committee on Peaceful Uses of Atomic Energy for the occasions and procedure of notification of the Committee on Peaceful Uses of Atomic Energy about operational changes, events and accidents, related to nuclear and radiation safety (promulgated in State Gazette, No. 26, 1988; amended in State Gazette, No. 28, 1988). § 3. (1)Infractions of the regulation shall be determined by statements, as specified in the Act on the Safe Use of Nuclear Energy and the Act of Administrative Violations and Sanctions. (2) Non compliance with the provisions of the regulation shall be penalized as an administrative infraction within the meaning of Article 140 of the Act on the Safe Use of Nuclear Energy, except for the case when it is subject to heavier penalty. § 4. The chairman of the Nuclear Regulatory Agency shall give directions on the application of the regulation and publish instructions, methodologies and other similar documents on its implementation. § 5. Licensees and permit holders shall align their systems for collection, registration, investigation, analysis and assessment of the events to the provisions of the regulation, as well as for determination and implementation of corrective measures for prevention of recurrence of the events within a period of one year after the promulgation of the regulation in the “State Gazette”. § 6. The present regulation is issued on the authority of Article 19, paragraph 1, item 8 of the Act on the Safe Use of Nuclear Energy. 20