Government Decree on the Safety of Nuclear Power Plants (No. 733 of 2008)

Section 1 assumed to occur less frequently than once during Scope of application any period of a hundred operating years, but at least once during any period of a thousand This Decree lays down provisions on the safety of operating years; nuclear power plants. Moreover, the Decree shall b) postulated accidents of Class 2, which can be apply, as necessary, to other nuclear facilities assumed to occur less frequently than once during equipped with a nuclear reactor. any period of a thousand operating years; 7) design extension condition shall refer to a

Section 2 situation caused by a rare external event, or a Definitions situation where the initiating event of an anticipated operational occurrence or Class 1 For the purposes of this Decree: postulated accident involves a common-cause failure in the safety systems, or a complex 1) annual dose shall refer to the sum of the combination of failures, and which the facility is effective dose arising from external radiation required to withstand without severe fuel damage; within the period of one year, and of the 8) severe accident shall refer to a situation where committed effective dose from the intake of a considerable part of the fuel in the reactor is radioactive substances within the same period of damaged; time; 9) probabilistic risk assessment shall refer to 2) criticality shall refer to a state whereby the quantitative assessments of probabilities and output and loss of neutrons, created in fission and consequences of event sequences originating from maintaining a chain reaction, are in equilibrium so threats influencing the safety of a nuclear power that a steady chain reaction continues; plant; 3) criticality accident shall refer to an accident 10) safety functions shall refer to functions caused by an uncontrolled chain reaction of important from the safety point of view, the fissions maintained by neutrons; purpose of which is to prevent the emergence or 4) anticipated operational occurrence shall refer propagation of disturbances and accidents or to to such a deviation from normal operational mitigate the consequences of accidents; conditions that can be expected to occur once or 11) redundancy principle shall refer to the several times during any period of a hundred implementation of systems important from the operating years; safety point of view using several parallel 5) accident shall refer to postulated accidents, subsystems, so that the system will be able to design extension conditions and severe accidents; function even though individual subsystems are 6) postulated accident shall refer to such a out of operation e.g. due to maintenance or deviation from normal operating conditions that failure; can be assumed to occur more rarely than once 12) diversity principle shall refer to securing during any period of a hundred operating years functions important from the safety point of view and which the nuclear power plant is required to through systems or equipment based on different withstand without severe fuel damage, even if operating principles, each of which is able to individual components of systems important to implement a function separately; safety are rendered out of operation due to 13) separation of subsystems shall refer to the servicing or faults; postulated accidents are placement of parallel subsystems of systems important from the safety point of view in The safety functions of a nuclear power plant shall separate premises; be defined and the related systems, structures and 14) operational separation shall refer to rendering components classified on the basis of their safety systems that secure each other as independent of significance. each other as possible, and the placement of Systems, structures and components important to systems important from the safety point of view in safety shall be designed, manufactured, installed rooms separate from other parts of the plant; and used so that their quality level, and the 15) separation principle shall refer to the assessments, inspections and tests, including separation of subsystems from each other and environmental qualification, required to verify operational separation; their quality level, are sufficient considering the 16) controlled state shall refer to a state where the safety significance of the item in question. reactor is shut down and the removal of its decay heat is secured; and Section 5 17) safe state shall refer to a state where the Ageing management reactor is shut down and non-pressurised, and the removal of its decay heat is secured. The design and construction of a nuclear power plant shall include provision for the ageing of Chapter 2 systems, structures and components important to General safety safety. The condition of systems, structures and components shall be monitored to ensure that they

Section 3 retain their operability and conformity in design- Assessment and verification of safety basis conditions. Their replacement by new or similar technology, as well as repairs and The safety of a nuclear power plant shall be modifications, shall be carried out in a systematic assessed when applying for a construction licence manner. and operating licence, in connection with plant modifications, and at regular intervals during the Section 6 operation of the plant. Management of human factors Unless compliance with safety regulations can be directly verified on the basis of the nuclear power Special attention shall be paid to the avoidance, plant’s design solution, compliance must be detection and correction of any human error demonstrated. Nuclear power plant safety and the during design, construction, operation and technical solutions of its safety systems shall be maintenance. The possibility of human error shall substantiated by using experimental and be taken into account in the design of the nuclear calculational methods. These include analyses of power plant and in the planning of its operation operational occurrences and accidents, strength and maintenance, so that human error and analyses, failure mode and effect analyses, and deviations from normal plant operations due to probabilistic risk assessments. Analyses shall be human error do not endanger plant safety. The maintained and revised if necessary, taking into impacts of human error shall be reduced by using account operating experience, the results of various safety design methods, including defence- experimental research, plant modifications and the in-depth, redundancy, diversity and separation. advancement of calculation methods. The calculation methods employed for Chapter 3 demonstrating compliance with safety regulations Limitation of radiation exposure and releases shall be reliable and well qualified for the of radioactive materials purpose. They shall be applied so that the resulting system design bases meet the acceptance Section 7 criteria with high certainty. Any uncertainty in the Radiation safety of nuclear power plant workers results shall be assessed and considered when defining safety margins. Occupational radiation exposure of nuclear power plant workers shall be kept as low as reasonably

Section 4 achievable. Furthermore, the design and operation Safety classification of nuclear power plants shall be implemented so that the radiation exposure of workers can be restricted in compliance with the provisions of the Radiation Act (592/1991) and Radiation Decree The safety impact of local conditions, as well as (1512/1991). the security and emergency preparedness arrangements, shall be considered when selecting

Section 8 the site of a nuclear power plant. The site shall be Limit for normal operation such that the impediments and threats posed by the facility to its environment remain extremely The limit for the annual dose of an individual in minor and heat removal from the plant to the the population, arising from the normal operation environment can be reliably implemented. of a nuclear power plant, is 0.1 millisievert (mSv). Based on this limit, the Radiation and Nuclear Section 12 Safety Authority (STUK) shall confirm release Prevention of accidents and mitigation of limits for radioactive materials during the normal consequences operation of a nuclear power plant. In order to prevent operational occurrences and

Section 9 accidents, and to mitigate the consequences Limit for an anticipated operational occurrence thereof, the operational principle of defence-in- depth shall be implemented in the manner laid The limit for the annual dose of an individual in down in this section. the population arising as the result of an anticipated operational occurrence is 0.1 mSv. Proven or otherwise carefully examined high- quality technology shall be employed in the

Section 10 design, construction and operation of a nuclear Limits for accident power plant. When arranging the operations of the licensee’s organisation, the aim shall be to ensure A postulated accident and a design extension reliable prevention of operational occurrences and condition shall not result in such high releases of accidents (prevention). radioactive materials that extensive measures A nuclear power plant shall encompass systems should have to be taken in the vicinity of the that facilitate the quick and reliable detection of facility in order to limit the radiation exposure of operational occurrences and accidents and prevent the population. the aggravation of any event. Accidents leading to The limit for the annual dose of an individual in extensive releases of radioactive materials must be the population arising as the result of an accident highly unlikely (control of operational is occurrences and accidents). - 1 mSv for Class 1 postulated accidents; Effective technical and administrative measures - 5 mSv for Class 2 postulated accidents; and shall be taken to mitigate the consequences of any - 20 mSv for a design extension condition. accident. Counter-measures for bringing an The limit for the release of radioactive materials accident under control and preventing radiation arising from a severe accident is a release which hazards shall be planned in advance (mitigation of causes neither acute harmful health effects to the consequences). population in the vicinity of the nuclear power plant, nor any long-term restrictions on the use of Section 13 extensive areas of land and water. Engineered barriers for preventing the dispersion The requirement applied to long-term effects will of radioactive materials be satisfied if there is only an extremely small possibility that, as the result of a severe accident, In order to prevent the dispersion of radioactive atmospheric release of cesium-137 will exceed the materials, the structural defence-in-depth safety limit of 100 terabecquerel (TBq). principle shall be implemented in the manner laid down in this section. Chapter 4 Dispersion of radioactive materials from the fuel Nuclear safety of the nuclear reactor into the environment shall be prevented by means of successive barriers

Section 11 which are the fuel and its cladding, the reactor Siting of a nuclear power plant cooling circuit (primary circuit) and the containment building. The fuel and reactor, the primary circuit of a of molten core material generated during a severe nuclear power plant and the secondary circuit of a accident. Direct interaction of molten core pressurised water reactor power plant, their water material with the load bearing containment chemistry, the containment building and safety structure shall be reliably prevented. functions shall be designed so as to meet the following safety objectives: Section 14 1) In order to assure the integrity of fuel Safety functions and provisions for ensuring them - the probability of fuel failure shall be low during normal operational conditions and anticipated In ensuring safety functions, inherent safety operational occurrences; features attainable by design shall be primarily - during postulated accidents, the rate of fuel utilised. In particular, the combined effect of a failures shall remain low and fuel coolability shall nuclear reactor's physical feedbacks shall be such not be endangered; and that it mitigates the increase in reactor power. - the possibility of a criticality accident shall be If inherent safety features cannot be utilised in extremely low. ensuring a safety function, priority shall be given 2) In order to ensure primary and secondary to systems and components which do not require circuit integrity, an off-site power supply or which, as consequence - the primary circuit shall be designed and of a loss of power supply, will settle into a state manufactured in compliance with high quality that is preferable from the safety point of view. standards so that the probability of hazardous In order to prevent accidents and mitigate the faults in structures and that of mechanisms consequences thereof, a nuclear power plant shall threatening their integrity remains extremely low be provided with systems for shutting down the and any faults which occur can be detected reactor and maintaining it in a sub-critical state, reliably through inspections; for removing decay heat generated in the reactor, - the primary circuit shall, with sufficient margins, and for retaining radioactive materials within the withstand the stresses arising in normal plant. Principles ensuring the implementation of operational conditions, anticipated operational these safety functions even in the event of a occurrences, postulated accidents and design malfunction must be applied in designing the extension conditions; systems in question. Such principles are - the primary circuit and systems immediately redundancy, separation and diversity. The most connected to it, and components important to the important systems necessary for transferring to, safety of the secondary circuit of a pressurised and remaining in, a controlled state must be water reactor, shall be reliably protected during capable of fulfilling their function even if any anticipated operational occurrences and all individual system component is inoperable and accident scenarios, in order to prevent damage even if any other component of the same system caused by over-pressurisation; and or of a supporting or auxiliary system necessary - in order to detect leakages, the facility shall be for its operation is simultaneously out of use due equipped with sufficient monitoring systems. to required repair or maintenance. 3) In order to ensure containment building Common-cause failures in safety systems shall integrity, only have minor impacts on plant safety. - the containment building shall be designed so as A nuclear power plant shall have on-site and off- to maintain its integrity during anticipated site electrical power supply systems. The operational occurrences and, with a high degree of execution of safety functions shall be possible by certainty, during all accident scenarios; using either of the two electrical power supply - pressure, radiation and temperature loads, systems. combustible gases, impacts of missiles and short- The plant shall be provided with systems, term high energy phenomena resulting of an structures and components for controlling and accident shall be considered in the design of the monitoring severe accidents. These shall be containment building; and independent of the systems designed for - the possibility of fracturing of the reactor operational conditions and postulated accidents. pressure vessel in a severe accident so that the Systems necessary for ensuring the integrity of the leak-tightness of the containment building would containment building in a severe accident shall be be endangered shall be extremely small. capable of performing their safety functions, even The nuclear power plant shall be equipped with in the case of a single failure. systems that ensure the stabilisation and cooling The plant shall be designed so that it can be fire, flood, explosion, pipe breaks, container brought into a safe state after a severe accident. breakages, missiles, falling of heavy objects and component failures.

Section 15 Fuel handling and storage Section 19 Monitoring and control of a nuclear power plant In the handling and storing of nuclear fuel, adequate cooling and radiation protection shall be The control room of a nuclear power plant shall ensured. Damage to fuel cladding during handling contain equipment that provides information on and storage must be prevented with a high degree the operational state of the nuclear reactor and any of certainty. The possibility of a criticality deviations from normal operation. Furthermore, a accident shall be extremely low. Fuel storage nuclear power plant shall contain automatic conditions shall be maintained such that the leak- systems that actuate safety functions whenever tightness or mechanical endurance of a fuel required and control and supervise their assembly is not substantially degraded during the functioning during operational occurrences and planned storage period. accidents. These automatic systems shall be capable of

Section 16 maintaining the plant in a controlled state long Management and storage of radioactive waste enough to provide the operators with sufficient time to consider and implement the correct Waste generated during the operation of a nuclear actions. power plant, the activity concentration of which The nuclear power plant shall have an emergency exceeds the limits set by the Radiation and control post independent of the control room, and Nuclear Safety Authority (STUK), shall be treated the necessary local control systems for shutting as radioactive waste. Waste shall be sorted, down and cooling the nuclear reactor, and for categorised and handled in an appropriate manner removing residual heat from the nuclear reactor in terms of its storage and final disposal, and and spent fuel stored at the plant. stored safely.

Section 20

Section 17 Decommissioning Protection against external events The design of a nuclear power plant shall take The design of a nuclear power plant shall take account of decommissioning of the facility so as account of external events that may challenge to limit the volume of waste destined for final safety functions. Systems, structures and disposal, accumulating during the dismantling of components are to be designed, located and the plant, and the radiation exposure of workers protected so that the impacts of external events on due to the dismantling of the plant, and to prevent plant safety remain minor. External events to be radioactive materials from spreading into the accounted for include at least exceptional weather environment. conditions, seismic events and other factors resulting from the environment or human activity. Design must also take account of illegal activities Chapter 5 undertaken to damage the plant, and a large Construction and commissioning of a nuclear airliner crash. power plant

Section 18 Section 21 Protection against internal events Construction The design of a nuclear power plant shall take During construction the licensee shall ensure that account of any internal events that may challenge the plant is constructed and implemented in safety functions. Systems, structures and compliance with the approved plans and components shall be designed, located and procedures. protected so that the probability of internal events In addition, the licensee shall ensure that the plant remains low and impacts on plant safety minor. supplier and sub-suppliers delivering services and Internal events to be considered include at least products important to safety act in the appropriate principles laid down in section 7 a of the Nuclear manner. Energy Act.

Section 22 Section 25 Commissioning Technical Specifications In connection with the commissioning of a The Technical Specifications of a nuclear power nuclear power plant, the licensee shall ensure that plant shall include the technical and the systems, structures and components and the administrative requirements for ensuring the plant as a whole operate as designed. plant’s operation in compliance with design bases At the commissioning stage, the licensee shall and safety analyses. The requirements for ensure that an expedient organisation is in place ensuring the operability of systems, structures and for the future operation of the nuclear power components important to safety, as well as the plant, alongside a sufficient number of qualified limitations that are to be observed in the event of personnel and instructions suitable for the equipment failure, shall also be presented in the purpose. Technical Specifications. The plant shall be operated in compliance with these requirements Chapter 6 and restrictions, and compliance with them shall Operating of a nuclear power plant be monitored and any deviations reported.

Section 23 Section 26 Operating Condition monitoring and maintenance The control room of the nuclear power plant shall The nuclear power plant shall have a condition be constantly manned by a sufficient number of monitoring and maintenance programme for operators aware of the state of the plant, systems ensuring the integrity and reliable operation of and components. Further, the control and systems, structures and components. This supervision of a nuclear power plant shall utilise programme shall define inspections, testing, written instructions that correspond to the current maintenance, replacements and other procedures structure and state of the plant. Written orders and for controlling operability and the impacts of the related instructions shall be provided for the operating environment. maintenance and repair of components. For operational occurrences and accidents, Section 27 instructions suitable for the identification and Radiation monitoring and control of releases of control of incidents shall be available. radioactive materials Operational measures concerning the nuclear power plant, as well as events having an impact The radiation levels of nuclear power plant rooms on safety, shall be documented so that they can be and the activity concentrations of indoor air and analysed afterwards. the gases and liquids in the systems shall be measured, releases of radioactive materials from

Section 24 the plant monitored, and concentrations in the Operational experience feedback and safety environment controlled. research Chapter 7 Nuclear power plant operational experience Organisation and personnel feedback shall be collected and safety research results monitored, and both assessed for the Section 28 purpose of enhancing safety. Safety-significant Safety culture operational events shall be investigated for the purpose of identifying the root causes as well as When designing, constructing, operating and defining and implementing the corrective decommissioning a nuclear power plant, a good measures. Improvements in technical safety, safety culture shall be maintained. The decisions resulting from safety research, shall be taken into and activities of the management of all account to the extent justified on the basis of the organisations participating in the abovementioned activities shall reflect its commitment to safety- promoting operating methods and solutions. operations of the organisation shall be monitored Personnel shall be motivated to perform and continuously developed. responsible work and an open working Significant functions with respect to safety shall atmosphere shall be promoted in the working be designated. Training programmes shall be community to encourage the identification, prepared for the development and maintenance of reporting and elimination of factors endangering the professional qualifications of the persons safety. Personnel shall be given the opportunity to working in these positions, and an adequate contribute to the continuous enhancement of command of the functions in question must be safety. verified. The organisation shall have access to professional

Section 29 expertise and technical knowledge required for the Safety and quality management safe operation of the plant, the maintenance of equipment important to safety, and the Organisations participating in the design, management of accidents. construction, operation and decommissioning of a The licensee shall have a group of experts, nuclear power plant shall employ a management independent of the other parts of the organisation, system for ensuring the management of safety and working as support for the responsible manager, quality. The objective of such a management said group convening on a regular basis to handle system is to ensure that safety is prioritised safety-related issues and issue recommendations without exception, and that quality management thereon if necessary. requirements correspond to the safety significance of the function. The management system shall be Chapter 8 systematically assessed and further developed. Entry into force and transitional provisions Safety and quality management shall cover all functions influencing nuclear power plant safety. Section 31 For each function, requirements significant in Entry into force safety terms shall be identified, and the planned measures described in order to ensure compliance This Decree will enter into force on 1 December with requirements. The processes and operating 2008. methods shall be systematic and based on The Decree will repeal the Decision of the instructions. Council of State on the general regulations for the Systematic procedures shall be in place for safety of nuclear power plants, issued on 14 identifying and correcting deviations significant in February 1991 (395/1991). terms of safety. Measures required for the enforcement of the The licensee shall commit and oblige its Decree can be undertaken prior to its entry into employees and suppliers, sub-suppliers and other force. partners participating in functions affecting safety, to adhere to the systematic management of safety Section 32 and quality. Transitional provision

Section 30 The following shall not be applicable to a nuclear Lines of management, responsibilities and power plant for which an operating licence was expertise issued prior to the entry into force of this Decree: section 10 (2-4), paragraph 3 of section 13(3), The lines of management in the organisation of a section 14, section 17 and section 19(3), unless nuclear power plant, alongside the positions and their application is justified with respect to the related responsibilities of employees, shall be technical solutions of the nuclear power plant in defined and documented. Furthermore, the question, under the principle laid down in section 7 a of the Nuclear Energy Act. Issued in Helsinki, 27 November 2008 Mauri Pekkarinen, Minister of Economic Affairs Pasi Mustonen, Senior Adviser