1. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making Temelin NPP Risk Panel A PSA and Safety Monitor Application Workshop Information IAEA Workshop City, Country XX - XX Month, Year Lecturer Lesson IV 3_11.7 Lecturer Lesson IV 3_11.7

2. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 2 TEMELIN PSA Project – –Temelin PSA Project carried out in 93-96 with NUS – –Scope: Level 1 & 2, Shutdown, External events – –Support to plant staff in analyzing day-to-day decision issues related to the areas like: Operating and maintenance strategies based on risk minimization Outage risk management Assessment of modifications Tech Specs issues (AOTs, STIs, LCOs)

3. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 3 Safety Monitor for Temelin – –To support risk informed decision making process at the plant a dynamic, flexible use of PSA models is required: Extensive scope of PSA models (thousands of BEs, MCSs) Experience in PSA techniques and plant specific models required Reflection of an actual/hypothetical configuration in the PSA model is time consuming (large number of modification steps) Quantification runtime (hardware, software, model scope) Interpreting results (PSA experience) – –Decision to implement a real-time risk calculation tool - Scientech/NUS Safety Monitor 2.0

4. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 4 Further PSA and SM Activities – –All Temelin PSA models update for current plant status – –Conversion of updated PSA models to SM models (internal events, shutdown, Level 2) – –Software update for 3.0 version enabling: Dual Unit interactions Faster solution engine Maintenance Rule

5. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 5 Safety Monitor Features – –on-line risk monitoring (real, hypothetical) – –restoration advice from safety viewpoint – –important operable components – –calculating risk for scheduled configurations – –limiting recommended configuration time These are useful features, but Safety Monitor databases could provide also other interesting information

6. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 6 Provides access to some of this information for any selected point in the operating history: equipment restoration advice combinations most contributing to risk system/trains inoperability indication probabilities of containment failure modes and STCs Risk Panel developed by Temelín PSA Department This application runs in MS Access 97 environment

7. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 7 Safety Monitor allows: to view operable components most important for plant safety in current configuration to view out-of-service components whose restoration reduces risk most significantly

8. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 8 However, these functions can be used only for last configuration calculated So, it is not possible to find out the most contributing components in any time point on risk profile (e.g. to find out reasons for high risk in past) So, it is not possible to find out the most contributing components in any time point on risk profile (e.g. to find out reasons for high risk in the past) When optimizing schedules, risk peaks cannot be easily removed without knowing the highest contributors When optimizing schedules, risk peaks cannot be easily removed without knowing the highest contributors ? ?

9. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 9 Risk Panel allows: è èto calculate the most contributing components for any time point of a risk profile è èto calculate component out of service combinations contributing mostly to the risk è èto indicate direct or „hidden“ train/system inoperability caused by the system dependencies

10. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 10 In this window, the user can enter a date and time of point to be analyzed (manually or by right- click to a desired point of the risk profile)...... and press „Analysis“

11. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 11 Configuration in the selected time point is loaded to database used for hypothetical calculations, calculated by Safety Monitor, and the most contributing components are listed by Safety Monitor...... however... Restoration of one individual component may not lead to risk reduction down to the acceptable level

12. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 12 Equipment Combinations As can be seen, for certain configurations, restoration of a single component made on Safety Monitor restoration advice does not reduce risk to the required level. This is solved by other Risk Panel function: „Combinations“ - calculating the risk most contributing combinations of components

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14. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 14 The „Analysis of Time Point“ dialog box provides another function: „Accident Progression“ - calculating probability of containment failure mode, in case that core damage occurs, on basis of PSA Level 2 This function can be also used for any time point in operating risk profile provided that Level 2 model is available

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16. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 16 Another function of „Risk Panel“ is System Panel that indicates availability of user defined plant systems depending on components out of that indicates availability of user defined plant systems depending on components out of service

17. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 17 Green color indicates that a system is operable Yellow color indicates that one division of a system is inoperable Orange color indicates that more than one division of a system is inoperable and red color indicates that a system or a division is inoperable Clicking on red, orange or yellow item shows reasons of inoperability

18. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 18 This screen shows portion of the Safety Monitor fault tree...... from „top“ event at system/division level...... to basic event(s) at component level. Clicking at a gate develops corresponding branch of the fault tree.

19. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 19...and so on...

20. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 20 User can customize the System Panel by... adding items moving items removing items User can also perform „what-if calculations“... System Panel..and System Panel recalculates the fault tree to show new system inoperability

21. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 21 Other features of Risk Panel – –indicates date/time in status bar when moving mouse over the risk profile – –allows easy selection of risk profile interval – –shows normal/logarithmic scale of risk profile – –lists configuration in points of risk profile where CDF exceeds user specified limit – –prints graphs of CDF, releases, cumulative risk, probabilities of containment failure

22. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 22 Enter begin and end date manually...... or drag mouse over risk profile Analyze of any point of hypothetical profile/schedule Set CDF limit...... and display configurations where CDF is above this limit Print graph and reports

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28. IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making 28 SUMMARY Risk Panel does not replace Safety Monitor but provides additional useful functions: comprehensive, easy analysis of past configurations for any point in operating history system inoperability information Level 2 basic information printouts of graphs and reports for archiving, presentations or reports