Managing severe accidents beyond design conditions (SAM) Vladivoj REZNIK, Engineering Director

Transcription

1 Managing severe accidents beyond design conditions (SAM) Vladivoj REZNIK, Engineering Director International Power Summit, Munich February 2014

2 Slovenské elektrárne, subsidiary of Enel Enel world presence Presence in 40 countries Installed capacity 97,839 MW 1 Annual production TWh EBITDA 16.7 bln. Capex bln. Customers 60.5 million Employees 73,702 Stock exchange Enel is listed on the Milan stock exchange (~1.36 mln shareholders). 14 companies of the Group are listed on Milano, Madrid, Mosca, New York stock exchanges and in other Latin American countries Data as of

3 Slovenské elektrárne, subsidiary of Enel Enel world presence NORTH-CENTRAL AMERICA North America, Costa Rica, Panama, El Salvador, Mexico and Guatemala: renewable presence BRAZIL Presence in generation and distribution 5.9 mln customers COLOMBIA First private operator in generation (21%) Second operator in distribution (25%) 2.6 mln customers PERU First operator in generation (28%) Second operator in distribution (21%) 1.1 mln customers ARGENTINA First private operator in generation (13%) Second operator in distribution (17%) 2.4 mln customers CHILE First operator in generation (33%) First operator in distribution (22%) 1.6 mln customers SPAIN ITALY First operator in First operator in generation (27%) generation (28%) First operator in First operator in distribution (43%) distribution (85%) 13 mln customers (power 32 mln customers and gas) (power and gas) RUSSIA First vertically integrated foreign operator (upstream, generation, sales) SLOVAKIA First operator in generation (78%) FRANCE Notable presence in wind generation ROMANIA Notable presence in wind generation Second operator in distribution (31%) 2.6 mln customers Enel estimates. Generation market share based on energy produced in the country, distribution market share on energy distributed in the country 3

4 Current nominal output of NPPs EBO and EMO EBO Unit 3 = 107 % = 505 MWe EBO Unit 4 = 107 % = 505 MWe EMO Unit 1 = 107 % = 470 MWe EMO Unit 2 = 107 % = 470 MWe 4

5 SE Nuclear Operations and EU Benchmark by UCF SE GOAL for 2014 = 93,5% (Loviisa + Olkiluoto) FINLAND = 92,35% (EBO+EMO) SLOVAKIA = 91,15% (9x units) GERMANY = 89,21% (8x units) SPAIN = 88,41% (6x units) SWITZERLAND = 87,97% (Dukovany + Temelín) CZECH REPUBLIC = 84,66% (10x units) SWEDEN = 71,22% SLOVENIA = 91,82% (Krško) NETHERLANDS = 90% (Borssele) HUNGARY = 89,01% (Pakš) BULGARY = 88,06% (Kozloduy) BELGIUM = 84,75% (Doel + Tihange) FRANCE = 79,09% (58x units) UNITED KINGDOM = 71,17% (16x units) Best 3-year average at SE in 2012 = 92,48% at EMO1 Date Title of presentation 5

6 Severe accident management EBO and in EMO SIPHON AND REACTOR CAVITY FLOODING DEPRESSURIZATION OF PRIMARY CIRCUIT MANAGEMENT OF HYDROGEN IN CONTAINMENT The SAM project is divided into following subprojects: BREAKER OF VACUUM IN CONTAINMENT ALTERNATIVE COOLANT SYSTEM ALTERNATIVE ELECTRIC POWER SUPPLY SYSTEM INFORMATION SOURCES C&I - PAMS AND CONTROL LONG-TERM HEAT REMOVAL FROM CONTAINMENT 6

7 SIPHON AND REACTOR CAVITY FLOODING SAM specific Localization and stabilization of the corium is one of the objectives of the strategy to manage the consequences of severe accidents. The most effective strategy for reactors of small and medium size appear to be localization and stabilization of the corium in the reactor vessel by cooling the outer surface of RPV (In-Vessel Retention Strategy). Measures are implemented to provide an intentional flooding of the reactor cavity. Date Title of presentation 7

8 SIPHON AND REACTOR CAVITY FLOODING Date Title of presentation 8

9 SIPHON AND REACTOR CAVITY FLOODING Siphon and valve for coolant inflow to reactor cavity on ventilation system TL 11 final conditions Date Title of presentation 9

10 SIPHON AND REACTOR CAVITY FLOODING Opening to the thermal and neutron shielding of RPV and floaters of coolant inflow to the outer surface of RPV Date Title of presentation 10

11 DEPRESSURIZATION OF PRIMARY CIRCUIT SAM specific Should the severe accident conditions are detected the primary circuit depressurization system is activated to prevent High Pressure core melt scenario. The depressurization valve is open by operator (the ability of depressurization valves to close is not required). At the time of the core relocation there should be in the reactor pressure vessel a relatively low pressure. The aim of the primary circuit depressurization is a mitigation of severe accidents and preventing the ejection of the core melt under high pressure. Target pressure in the primary circuit is less than 2 MPa. Date Title of presentation 11

12 DEPRESSURIZATION OF PRIMARY CIRCUIT Date Title of presentation 12

13 DEPRESSURIZATION OF PRIMARY CIRCUIT Date Title of presentation 13

14 MANAGEMENT OF HYDROGEN IN CONTAINMENT SAM specific During a severe accident involving core damage of pressurized water reactors a significant amounts of combustible gases (H2, CO) can be produced. The internal ("in-vessel") phase of an accident causes mainly the production of H2 as a result of oxidation of zirconium fuel elements and assemblies components and structures made of stainless steel. Date Title of presentation 14

15 MANAGEMENT OF HYDROGEN IN CONTAINMENT Date Title of presentation 15

16 BREAKER OF VACUUM IN CONTAINMENT SAM specific Breaker of vacuum in the containment is designed to avoid development of a deep vacuum in the containment. The liner of containment wall can be potentially damaged and can loose the tightness capability under accident conditions. This situation can happen when the containment spray fails to stop under containment low pressure conditions. The containment breaker is controlled manually by operator (automatically at Mochovce 3 and 4). It allows to transfer the air from air traps to the central part of containment. There is no opening of containment to the external environment. Date Title of presentation 16

17 BREAKER OF VACUUM IN CONTAINMENT Date Title of presentation 17

18 ALTERNATIVE COOLANT SYSTEM SAM specific The alternative coolant system is designed for specific use under severe accident conditions. Two tanks (three in Bohunice) with capacity of 1000 m3 of borated coolant provide extra boration system. Pumps pump this coolant to the following: - Reactor pressure vessel (PC pressure bellow 2 MPa). - Containment Spray System - Spent Fuel Pool There are two tanks, three pumps. The EMO1,2 Alternative Coolant System is interconnected with MO 3,4 Alternative Coolant System. Date Title of presentation 18

19 ALTERNATIVE COOLANT SYSTEM Date Title of presentation 19

20 ALTERNATIVE ELECTRIC POWER SUPPLY SYSTEM SAM specific Alternative electric power supply system (DG SAM) is a new device designed to power consumers that are intended for the prevention and management of severe accidents. SAM DG: Power 1,2 MW, (2,5 MW in Mochovce) Voltage 6 kv Electrical power from SAM DG is supplied to: - Valves - Pumps - Workplaces on control room and Emergency Control Center SAM DG is stable and is common for two units. Date Title of presentation 20

21 ALTERNATIVE ELECTRIC POWER SUPPLY SYSTEM Date Title of presentation 21

22 ALTERNATIVE ELECTRIC POWER SUPPLY SYSTEM Date Title of presentation 22

23 INFORMATION SOURCES I&C - PAMS & CONTROL SAM specific Severe accidents control panel: Panel is placed in each control room (1 & 2unit) and also in the Emergency Response Center (technical support group) Controlled systems: - Alternative electric power supply system - Alternative coolant system - Vacuum breaker - Depressurization of PC - Reactor cavity flooding and drainage of bubble tower trays - Long term heat removal Back-up control system is installed in Emergency Control Centre Date Title of presentation 23

24 INFORMATION SOURCES C-PAMS & CONTROL Obr Čelný pohľad na integrované pracovisko SKR SAM + ZI + TBD na BD Date Title of presentation 24

25 LONG-TERM HEAT REMOVAL FROM THE CONTAINMENT The existing system modified for operation under SAM conditions Design criterion: Ensure sufficiently powerful and reliable long-term heat removal from containment Operability recovery strategy of existing safety systems is adopted - Containment Spray System. New pipelines are designed to ensure the ultimate coolant delivery to the reactor cavity, Spent Fuel Pool and Alternative Coolant System tanks (make up). Date Title of presentation 25

26 CONTAINMENT SPRAY SYSTEM REACTOR HALL SPENT FUEL POOL REACTOR AXIS PASSIVE HYDROGEN RECOMBINERS VENTCENTRUM Date Title of presentation 26

27 Mobil DG set one per unit Power [kva/kw] 350 / 280 Voltage [ V ] 230 / 400 Current [ A ] 507 Frequency [ Hz ] 50 Fuel tank [ l ] 900 Date Title of presentation 27

28 Mobil Feedwater set one per unit Volume flow [m3/hr] 32 Discharge pressure [ bar ] 70 Power [ kw] 70 Date Title of presentation 28

29 Emergency Response Center ERC Bunker ERC SAM - operators ERC Radiation - group ERC TSC - group Date Title of presentation 29