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Flamanville 3 Safety classification

Flamanville 3 Safety classification. Summary. French regulation for the safety classification Objectives of the classification of SSC Principles for the safety classification Plant states and PIEs Functional classification of SSC Safety classification of electrical and I&C components

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Flamanville 3 Safety classification

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  1. Flamanville 3Safety classification

  2. Summary • French regulation for the safety classification • Objectives of the classification of SSC • Principles for the safety classification • Plant states and PIEs • Functional classification of SSC • Safety classification of electrical and I&C components • Safety classification of mechanical components • Seismic classification Flamanville 3 Safety classification- 06/06/2014

  3. French regulation for safety classification The French nuclear fleet is made up of PWR reactors The French regulation for NPPS concerns : Nuclear and conventional pressure retaining equipment Environmental protection Protection against radiations Quality Assurance Other aspects are handled by guides which are not mandatory rules : For existing NPPs Basic Safety Rules : Regarding SSCs classification RFS IV.1.a, RFS IV.2.a, RFS IV.2.b For EPR most of the Basic Safety Rules, including those dealing with the safety classification are replaced by the “Technical Guidelines for the design and construction of the next generation of PWR NPPs”, issued on October 2000. Flamanville 3 Safety classification- 06/06/2014

  4. Objectives of the classification of SSC The safety classification of the Structures Systems and Components aims at ranking them according to their safety significance They shall then be designed, manufactured, operated with a quality and reliability commensurate with their safety class. Flamanville 3 Safety classification- 06/06/2014

  5. Principles for the safety classification The safety significance of a SSC is established by consideration of its role in the fulfillment of the 3 objectives : integrity of the Reactor Coolant Pressure Boundary ability to shutdown the reactor and maintain it in a safe state ability to prevent the accidents or to limit their radiological consequences The method for classifying the safety significance of a SSC is based on deterministic methods, according the following factors : the safety function(s) to be performed by the item; the consequences of failure of the item to perform its function; the time following a PIE at which, or the period throughout which, it will be called upon to operate; the level of defence in depth to which it belongs. The PSA are used afterwards to refine the classification and to identify possible new PIEs. Flamanville 3 Safety classification- 06/06/2014

  6. Plant states and PIEs Design Basis Conditions Plant Condition Categories : PCC 1 to 4 : PCC 1 : normal operation PCC 2 : anticipated operational occurrences (frequency 10-2 ry to 1) PCC 3 : Design Basis Accidents (frequency 10-4 ry to 10-2 ry ) PCC 4 : Design Basis Accidents (frequency 10-6 ry to 10-4 ry ) Examples of PCC 4 : large break LOCA, SLB, SGTR Beyond Design Conditions Risk Reduction Categories : RRC-A : prevention of core melt (complex sequences) Examples of RRC-A : SBO, TLOCC, TLFW RRC-B : prevention of large releases (severe accidents) Flamanville 3 Safety classification- 06/06/2014

  7. Physical states of the plant To take into account the time following a PIE at which a mitigation function is used 2 states are defined : Controlled state : state when the fast transient is finished and the plant stabilized : Core subcritical Core power removed The activity is tolerable Safe state : state when the fast transient is finished and the plant stabilized : Core subcritical Activity within the limits of corresponding PCC or RRC-A Core power removed in a sustainable way Flamanville 3 Safety classification- 06/06/2014

  8. Functional classification Flamanville 3 Safety classification- 06/06/2014

  9. Functional classification Flamanville 3 Safety classification- 06/06/2014

  10. Functional classification of SSC The functional classification concerns primarily the mitigation functions, but mechanical equipment having a role as a barrier to hold radioactive material is assigned to a functional class. Functional classification does not exist on the NPPs in operation : the functional role is taken into account by an electrical classification, with comparable requirements : 1E <-> F1A 2E <-> F1B IPS-NC <-> F2 Flamanville 3 Safety classification- 06/06/2014

  11. Requirements for safety classified systems They are commensurate with their safety class • Active failure ; passive failure after 24 h • Redundancy required • Redundancy or diversity required Flamanville 3 Safety classification- 06/06/2014

  12. Safety classification of Electrical and I&C components The safety classes of the electrical and I&C components are directly derived from their functional safety classes The code used for the design of electrical and I&C equipment is RRC-E (French code), either for EPR or for existing NPPS (for EPR, if another code is used, gaps from the RCC-E shall be justified) Flamanville 3 Safety classification- 06/06/2014

  13. Mechanical classification It takes into account : The retention of active fluid (role of barrier) The functional safety role M1 : primary circuit, including its isolation M2 : circuits liable to contain active primary fluid in accidental situations : secondary circuit, Emergency Core Cooling System, Containment penetration and isolation M3 : other mechanical classified safety function (e.g. F1 functions not liable to contain active primary fluid in accidental situations) Emergency Boration System, Emergency Feedwater System, Component Cooling Water System, Essential Service Water System Flamanville 3 Safety classification- 06/06/2014

  14. Requirements on safety classified mechanical components The requirements on design and manufacturing of mechanical equipment are based primarily upon their safety function (mechanical classification). But they take also into account several other parameters which can lead to stronger requirements : the operation conditions (pressure, temperature, number of mechanical cycles) the French regulation upon nuclear pressure equipment (based on the radioactivity in normal service and on the pressure)(1) and the technical rules concerning the operation of the main primary and secondary circuits (2) the French regulation upon conventional pressure equipment (3) Order no. of December 12, 2005 concerning nuclear pressure equipment Order no. of November 10, 1999 concerning the operation of the main primary and secondary circuits Decree no. 99-1046 of December 13, 1999 and order of December 21, 1999 concerning pressure vessels Flamanville 3 Safety classification- 06/06/2014

  15. Component classes of pressure retaining components For safety classified pressure equipment, they are 3 component classes with decreasing requirements Q1 : primary circuit and the main steam and feedwater systems up to the isolation valves ; application of the RCC-M1 code (French code) (equ to ASME A) Q2 : other nuclear mechanical components ; application of the RCC-M2 code or ASME III (US) or KTA (Germany) (equ to ASME B) Q3 : conventional components ; application of the European pressure equipment codes (equ to ASME C) Flamanville 3 Safety classification- 06/06/2014

  16. Requirement of non pressure retaining mechanical components The requirements on design and manufacturing of safety classified mechanical equipment which are not submitted to pressure are defined on a case by case basis : ventilations Reactor Pressure Vessel internals main diesels fuel handling machine Flamanville 3 Safety classification- 06/06/2014

  17. Seismic classification All F1 classified systems and equipment are assigned to the seismic class SC1, as well as M1 and M2 mechanical components. F2 systems and equipment are seismic classified on a case by case basis, as well as M3 mechanical components. For example, F2 systems and equipment used in accidental situations which may be caused by an earthquake are assigned to the seismic class SC1: Fire protection equipment Station Blackout diesels Severe accident mitigation equipment The requirement of SC1 SSCs is integrity, functional capability or operability during or after a design earthquake according to their safety function Seismic class SC2 concerns non safety related equipment liable to damage SC1 systems in the event of an earthquake (or dedicated to protect them). The requirement of SC2 equipment is stability or integrity after a design earthquake Flamanville 3 Safety classification- 06/06/2014

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