Reaction during an earthquake of Kozloduy NPP

1. Reaction during an earthquake of KozloduyNPP TsvetomirMarinov

2. 1. Preliminary activities (before the earthquake) Seismic instrumentation Seismic Instrumentation of NPP "Kozloduy" consists of several separate independent seismic systems that operate in parallel and are NOT overlapping each other’s functions : • The devices forIndustrial Seismic Protection of blocks 5 and 6 consists of 2 independent sets for each of the blocks. Each kit contains 3 identical interchangeable sensors and 3 blocks for commutation, located at the lowest elevation of the reactor compartment. The system is designed to automatically shut down the reactor if accelerations of seismic motion exceeding 0.05g are recorded on the reactor foundation slab.

3. Seismic monitoring system for blocks 5 and 6 • Sensors of this system are installed only block 6, while information panels are installed on both blocks. The system meets the requirements of NRC RG 1.12, Nuclear Power Plant Instrumentation for Earthquakes. It is able to quickly calculate parameters of the seismic movement of "free field" in the characteristic points of the structure of Block 6. Estimates apply to fully to block 5, for it has practically the same structures and equipment of the units. The system is purely informational and is currently not linked to the automatic shutdown of reactor.

4. System of Accelerographs for Seismic Monitoring of equipment and structures (SASMES)     The system (SASMES) mounted in the NPP "Kozloduy" is used for seismic monitoring of. the equipment and building structures. The system consists of 10 pieces autonomous seismic instruments installed on NPP "Kozloduy" (1 to 6th blocks). These are ten Accelerographs of the American company KINEMETRICS which have different systems for recording registered acceleration of gravity:- SMA-2 performes magnetic recording on tape, 3 pieces;- SSA-2 records events on RAM 256 KB-3 pieces.;- ETNA records events on the PCMCIA memory card 64MB -4 pieces.The sensors of the SMA-2, SSA-2 and ETNA are accelerometers of type FBA. The three types if accelerographs record all the events of acceleration over 0.01g

5. Accelerograph –SSA2

6. Accelerograph ЕTNA

7. Local seismological network (LSM). One of the tasks of the project BUL 9 / 012 "Site and Seismic Safety of Kozloduy and Belene NPPs" is installed on the creation of local seismological network (LSN) for monitoring of low seismicity – micro-earthquakes in the subregion (area with a radius of 30 km) of the NPP " Kozloduy ". It is designed and constructed in accordance with the requirements and recommendations of the International Atomic Energy Agency, presented in: IAEA-TECDOC-343 "Application of Microearthquake Surveys in Nuclear Power Plant Siting"; IAEA Safety Series No.50-SG-S1 (rev .1) "Earthquake and associated topics in relation to nuclear power plant sitting". Creating a database of registration results of this network makes it possible to seek solutions to problems such as reducing a magnitude threshold of registered seismic events and increasing the accuracy of monitoring their main parameters, quantitative evaluation of the characteristics of the seismic regime in the subregion and region (radius 1.5 °) of the plant, and refining the existing estimates of the maximum possible magnitude of the main regional seismic structures. These problems in areas with high seismicity (of platform type), as the subregion of “NPP-Kozloduy", can be solved only in the course of continuous observations in significant duration in time. The network was put into operation in 1997.

8. 2. Activities after an earthquake 2.1. Emergency plans The main legal and regulatory requirements for the structure and organization of emergency preparedness in Bulgaria are defined in the Safe Use of Nuclear Energy Act, the Disaster Protection Act and the Ministry of Interior Act. The emergency plan of “NPP-Kozloduy" is based on the Ordinance on emergency planning and emergency preparedness for nuclear and radiological emergency. The staff of "NPP Kozloduy" is trained and is familiar with the rules for their own protection and the protection of the population and the environment. The staff is trained and familiar with procedures and instructions aimed at preventing serious effects or reduce the effects to a minimum. Training programs and exercises constantly expand and cover all staff.

9. Emergency organization is based on constantly maintained emergency duty, ensuring the smooth establishment of emergency structures if needed. Emergency teams are created from the staff of NPP "Kozloduy". The specific duties of positions in the emergency plan and procedures for their implementation are regulated in separate instructions and procedures. In the emergency plan are provided measures relating to the management of nuclear facilities during and after an earthquake, with a focus on forecasting and preventive. The site of "NPP Kozloduy" is designed and has the necessary infrastructure to respond to seismic events:

10. За АЕЦ „Козлодуй”, работещ във всички стационарни състояния и преходни процеси при нормална експлоатация, са предвидени следните аварийни мероприятия при сеизмично събитие: • Първоначална оценка на изходното събитие - извършва се от оперативния персонал на смяна под ръководството на Главен дежурен на атомната електроцентрала (ГДАЕЦ) ; • Активиране на Аварийния план, оповестяване и информиране; • Последващи оценки на аварийното състояние; • Дейности по управление на аварията - избор на стратегията, разпореждане и изпълнение на съответните операции; • Дейности по защита на персонала; • Радиационен контрол и радиационна защита; • Противопожарни мероприятия; • Взаимодействие на аварийните структури на АЕЦ с Националните и регионалните органи при аварии; • Ограничаване разпространението и третиране на радиоктивни отпадъци; • Общ времеви график за провеждане на аварийните мероприятия. Аварийният план е адекватен, а мерките за управление на ядрените съоръжения по време и след максимално разчетно земетресение са определени.

11. 2.2.Организационно технически мерки в АЕЦ “Козлодуй” В аварийните планове на АЕЦ „Козлодуй“ се предвижда наличие на мобилно оборудване и запаси, които да са на разположение и да са годни за употреба. Разработена и реализирана е Програма за преглед и оценка на готовността за управление и намаляване на последствията от надпроектни аварии, външни и вътрешни въздействия. Тя представлява серия от мерки, които са приложени към всяко едно от Ядрените съоръжения на площадката на АЕЦ. Всички изброени проверки са реализирани и са изготвени отчети по тях с конкретни заключения за работоспособността на оборудването. Според наличните анализи за Ядрените съоръжения на АЕЦ „Козлодуй”, те демонстрират високо ниво на ядрена, радиационна и технологична безопасност, съизмерима с тази на най-добрите подобни централи. Проектът и експлоатационната практика покриват изискванията на националното законодателство.

12. 2.3.Stocks of materials The emergency plan of “NPP-Kozloduy" provides necessary resources. There is a warehouse in the Emergency management center (EMC). The warehouse stores emergency equipment for emergency groups and teams. In case of emergency, equipment and a large quantity and other inert materials from the facility stores can be used also. NPP "Kozloduy" has developed instructions for ensuring adequate supplies of fuel and oil for the continuous operation of emergency power supplies. For those emergency responses there are set procedures for procurement and provision of resources and reserves, as well as mobile equipment. They result from the measures to restore or compensate for impaired function of safety and prevent or mitigate damage to the core.

13. 2.4.Conjunction with the National Emergency Plan • There is a system of liaison with the national emergency services and the inclusion of emergency operations headquarters in the National Contingency Plan. Officials responsible for overall management of activities under PA is the Chief of emergency work (CEW). Until the formation of emergency response teams for emergency duties the responsibilities of CEW are performed by the Chief on duty of the NPP.The external forces and resources for "NPP Kozloduy“ are defined in the National Emergency Plan for carrying out rescue and emergency repair work in case of disasters, accidents and catastrophes. • According to the National Emergency Plan public authorities are required to maintain reserve funds for decontamination, food, clothing and fuels for the application of the plan. Transport is also provided in the event of evacuation activities of the population. • Providing fire and emergency rescue operations in the territory of NPP "Kozloduy" and the area of ​​preventive measures is provided by Regional service for fire safety and civil protection of the NPP"Kozloduy" and the town of Kozloduy. According to the National Emergency Plan the Service for fire safety and civil protection Sofia has a reserve of forces and means to implement them if necessary in the area for emergency and precautionary measures.

14. 3. Evaluation of the adverse effects of seismic-induced damage in the area around the plant To take into account possible adverse effects of earthquake-induced damage to the national infrastructure around the plant on its ability to maintain their safety function after a seismic event, we need to specify when and how seismic failures and damage can be expected. Possible adverse effects on the plant is mainly limited to: • Loss of external power supply; • Destruction of roads and bridges; • Extensive destruction in the nearest cities, leading to inability to complete the operational staff of the plant; • Potential faults in the transmission network and subsequent gassing, etc.; • Accidents in the water supply system "Iron Gates 1 and 2" with subsequent flooding.

15. Than you for your attention!