STRESS TESTS ACTION PLAN LEONTI CHALOYAN DEPUTY CHIEF ENGINEER ON MODERNIZATION

Transcription

1 STRESS TESTS ACTION PLAN LEONTI CHALOYAN DEPUTY CHIEF ENGINEER ON MODERNIZATION VIENNA MARCH 27-29,

2 ANPP * The ANPP is located in the western part of Ararat valley, 30 km west of Yerevan, close to Metsamor town 2

3 The ANPP consists of two WWER-440 (V-270) power units, seismically upgraded V-230 models Unit 1 was commissioned in 1976 and Unit 2 in 1980, respectively Units 1 and 2 were shutdown in1989, February and March correspondingly In 1993 the Government of Armenia made a decision on restart of the ANPP Unit 2 Unit 2 was connected into power grid in 1995 Unit 1 remains in long-term shutdown The design lifetime of Unit 2 expired in September On April 19, 2012, the Government of Armenia adopted a Decision on the ANPP Unit 2 lifetime extension Decision is taken to built new nuclear unit at the same site 3

4 40% 18% 42% Thermal (gas) Nuclear Hydro 4

5 Due to the known objective reasons, the construction of a new NPP in Armenia may be launched no earlier than Usually the duration of such facilities construction is around 6-7 years, i.e., the commissioning of the ANPP's replacing capacity is not expected before In this situation, in order to refrain from repetition of the energy crisis, on April 2012, the Government of Armenia adopted a Decision on the ANPP Unit 2 lifetime extension. 5

6 In 2012 the ANPP submitted to ANRA a request for Life Time Extension (LTE), and ANRA issued requirements for LTE (Governmental Decree N1085-N). The first stage of the LTE process, i.e., a feasibility study and the ANPP complex investigation process, started in The summary assessment of the current technical condition of the irreplaceable components and their residual life, as well as the ANPP Unit 2 safety condition, didn t reveal fundamentally insolvable problems which would prevent the decision-making on the ANPP Unit 2 lifetime extension outside its design life. In regard to the scheduled activities and availability of safety upgrading programs, ensuring the required safety of the ANPP Unit 2 outside its design life seems to be quite realistic. 6

7 An agreement was reached with the Regulatory Authority for the following: Temporary permissions will be granted for operation in the period from 2016 to May Temporary permissions will be granted for operation in the period from June 2017 to June An updated SAR complying with current requirements of the Government Decree N2013-N will be submitted to ANRA in The final decision on license for operation is planned to be issued by ANRA in the beginning of

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9 In August 2015, ANRA submitted to the EC s Directorate- General for Energy its NR for the EU PR. The Revision 1 of this NR National Report Stress Test for Armenian Nuclear Power Plant issued on 17/03/2016 has been the basis for the PR. EU PRT was established by EC, based on ENSREG Members proposals on 02 March 2016 The country visit of the PRT (Country Review) to Armenia took place from 20 to 24 June

10 Based on the stress test results, the following conclusions were made: The minimum value of HCLPF, determined on the basis of the results of the SSEL complete scope review, constitutes 0,57g. The minimum level of seismic resistance for the ANPP structures, ensuring the integrity of the confinement is ~ 0,74g. This value corresponds to reinforcement of the pipeline penetrations from the confinement. 10

11 Based on the stress test results, the following conclusions were made: The flooding of ANPP site due to external natural phenomena is not possible. The flooding of DGS basement area can be considered as the main hazard during the heavy rainfalls. The probability of any serious consequences during heavy rainfall is negligibly low. The analysis revealed that the plant has some weak points and the implementation of measures to increase the robustness is desirable. 11

12 Based on the stress test results, the following conclusions were made: The ANPP project did not consider all possible natural phenomena as it required by modern standards ( tornados, dusty storms). The standard values of characteristics of weather conditions considered in the design ensure the plant operation under extreme weather conditions during wind load, snow load, high temperature, low temperature. From additionally (related to the project) considered natural phenomena the dusty storm combined with strong wind can create a threat. There is no analysis of influence of tornado on the plant 12

13 The ANPP design has a number of provisions aimed at prevention of the core damage in case of loss of electric power and loss of ultimate heat sink. All these provisions ensure time margins for recovery actions. Failures of these provisions represent potential cliff-edges, which could result in irreversible core damage. All available options either for loss of power supply or loss of ultimate heat sink, or both are sufficiently described in the National Report. Despite the robustness of power plant design, some safety improvements are recommended. 13

14 Despite of various programs of international aid and support, the progress in SAM program development and implementation is quite slow and delayed in respect to the original schedules. In respect to SAM the current level of safety of the ANPP is clearly lower than the EU average. However, this level will be increased in near term due to the introduction of SAMGs expected in The ANPP employed general WESTINGAUSE Owner Group (WOG) methodology for the SAMG development. Only in the mid-term, with the implementation of the activities pursuant to "Stress Tests" recommendations, the ANPP can reach an acceptable level. 14

15 The improvements implemented "post-fukushima" at the Armenian NPP were aimed to address three challenges: 1. Protections of the unit lower (basement) rooms against flooding due to damage of water containing vessels and pipelines. 2. Provision with emergency reserve of cooling water. 3. Upgrading the reliability of the first and second category emergency power supply systems. 15

16 To prevent the EDGS flooding, an opening of 0,5m height, 50m length was made on the outlet channel wall ensuring water removal from the EDGS in case of the channel overfill; The basement rooms of diesel generator station were fenced to prevent penetration of water in the basement rooms from outside; The basement rooms of diesel generator station were equipped with the water detection alarm, movable pumps for water pumping out, and the procedures on personnel actions in irregular situations were reviewed; At the minus elevations of the turbine hall the doors to the boron rooms of the Units 1 and 2 have been bricked-up; Check valves have been installed on the drainage pipelines to prevent water flow from the turbine hall to the cable tunnels. 16

17 A circuit have been installed for the Essential Consumers Cooling System ponds makeup by diesel pumps from the outlet circulating channel; Seismic enforcements were performed for pipelines and specific components of the Unit 1 storage pool cooling system; Three wells were drilled and additional cooling water system has been installed. It is planned to drill six more wells in 2017; The Demineralized Water Storage Tanks make-up circuit with fire trucks has been installed. 17

18 Seismic enforcement of the diesel fuel emergency reserve tanks ensuring the DG operation more than 72 hours; Load of the direct current system accumulator battery have been decreased (approximately for 30%), and a temporary arrangement have been implemented (until mobile DG is procured) for recharge of accumulator batteries from a separate DG used for make-up of the physical protection system. 18

19 Identification of the SSC required strengthening using the Seismic PSA The seismic PSA was developed by the Bulgarian company Risk Engineering within the EC assistance program. Implementation of Emergency gas removal system The design is developed. The remaining issues will be solved within the LTO program. The ANPP plans to install the system and implement it in the period of Seismic margin evaluation of the fire extinguishing system and issue the recommendations. Contract is concluded with TsKTI VIBROSEISM, Russia Seismic upgrading of the I&C equipment and seismic monitoring system: Reactor Protection Seismic Protection and Monitoring The high priority activity is included in the tender specification for new OSA. 19

20 Implementation of the technical solution in order to avoid damage of the DG building window in case of extreme wind conditions. Will be implemented in Review of the PSA level 1 taking into account the following: Description and justification of extreme natural phenomena; Justified choice of combinations of different natural factors; Meteorological characteristics for different frequencies of excess; Possible impact of tornado. Implementation is planned for Study of the need of filtering devices on air inlets of diesel generators. Implementation is included in the new OSA activity program for

21 Review of the existing symptom-based operating procedures. Develop personnel training programs. Under implementation in the framework of US DOE assistance program. Documentation package is submitted to the Regulatory Authority for consideration. Performance of analyses of the Units 1&2 SFP cooling and implementation of additional measures based on the performed analyses. Completed analyses of options for implementation. Implementation is planned for Implementation of logics (systems) of water supply to primary circuit, Unit 1&2 SFP s, SGs 1-6, DWSTs 1-4 from alternative water sources. Completed analyses of options for implementation. Implementation is planned for

22 Replacement of all reversible motor generators with inverters. To be implemented in 2018 in the framework of LTO program. Purchase of autonomous alternative power supply sources. Implementation is planned for Purchase of autonomous alternative means (Boron injection, SG make-up, SFP 1&2 cooling, ESWS and DWST 1-4 water supply). Analyses and relevant calculations were performed in the framework of OSA program. Characteristics of required equipment were specified. Implementation is planned for

23 Analysis of MCP shaft sealing. Assure MCP seals long-term (more than 24 hours) operation in case of cooling failure. Implementation is planned for Development of a full set of severe accident management guidelines. Under implementation in the framework of US DOE assistance program. Implementation is planned for Modernization of Emergency Core Cooling System. To be implemented in 2019 in the framework of LTO program. Design activities are under implementation Modernization of the spray system. To be implemented in 2018 in the framework of LTO program. Design activities are under implementation 23

24 Improvement of containment tightness. The activities will be performed in the framework of EC assistance АР17 program. Measuring of hydrogen concentration in containment. Under implementation in the framework of US DOE assistance program. Implementation is planned for Installation of afterburners and passive autocatalytic hydrogen recombines. Implementation is planned for Detailed analysis of possible hydrogen accumulation in rooms outside the containment. Implementation is planned for

25 Perform detailed safety margin assessment in terms of rainfall flooding of the ANPP site and calculations aimed to prove that protection measures are enough to prevent mudflows impact on the ANPP systems. Implementation is planned for It is recommended to implement detailed analysis for lightning impact on the ANPP. Implementation is planned for During the "cold" shutdown and refueling the DGLS (Diesel Generator Load Sequencer) program is not foreseen. Implement DGLS program for "cold" shutdown and refueling modes. Implementation is planned for

26 Development of the ANPP Unit 2 seismic safety evaluation program for new design-basis earthquake level (DBE) = 0.42g. The program will be developed in Analysis and assessment of the ANPP Unit 2 volcanic hazard for those volcanic effects for which the protection is possible (according to SSG-21): ballistic projectiles tephra fallout It is expected to implement recommendations in Seismic reassessment of the Stand-by DGES structure components. The activity will be implemented in Seismic assessment of the fire trucks garage building and issue of recommendations. The activity will be implemented in

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