FLEX and Beyond Design Bases Event Response

Transcription

1 FLEX and Beyond Design Bases Event Response Roy Harter RLH Global Services Workshop on Understanding the Role of Severe Accident Management Guidelines December 14-15, 2016

2 IAEA SAMG-D Modules Module 1: Fundamentals on Reactor Safety Basic concepts of nuclear safety. Fundamental safety principles, defence-indepth. Nature and role of procedures and guidelines. Main elements to develop SAMG. Module 2: Severe Accident Challenges and Strategies Associated radiological phenomena with severe accidents. Processes that challenge fission product barriers. Strategies to protect fission product boundaries. Module 3: Severe Accident Management Guidelines Description on how strategies are developed into plant specific guidelines, to most effectively manage an accidental scenario. Module 4: Implementation, Requirements and Infrastructure Organizational measures needed to execute the SAMGs. Implementation of these measures in the overall plant emergency organization. Plant specific verification and validation 2

3 What is FLEX? NRC Order EA , Requirements for Mitigation Strategies for Beyond- Design-Basis External Events Approach is outlined in NEI 12-06, Rev 2 Provides a diverse and flexible means to prevent fuel damage while maintaining containment function in beyond design basis external event conditions resulting in: Extended Loss of AC Power, and Loss of Normal Access to the Ultimate Heat Sink Objective: Establish an essentially indefinite coping capability by relying upon installed equipment, onsite portable equipment, and pre-staged offsite resources 3 3

4 4 FLEX Objectives

5 Diverse & Flexible Coping Capability (FLEX) Emergency Plans Emergency Response Prevention of Fuel Damage Emergency Plans SAMGs SBO Coping Capability Increased Defense-in- Depth SAMGs Diverse & Flexible Coping Strategy (FLEX) SBO Coping Capability Protection of Plant Equipment Design Basis External Events Design Basis External Events Current Current plus FLEX 5

6 6 Diverse & Flexible Coping Capability (FLEX)

7 FLEX Tie To NRC Tier 1 Recommendations Mitigation of Beyond Design Seismic Event (Tier 1) Mitigation of Beyond Design Basis Flooding (Tier 1) Mitigation of Loss of Ultimate Heat Sink (Other Items in SECY ) Mitigation of Other Beyond Design Bases External Events (Tier 1 Support) Extended Station Blackout Coping sufficient to allow initiation of FLEX (Tier1) Diverse & Flexible Mitigation Capabilities Including Maintenance/Guidelines/ Training/Protection Additional Support Equipment from other plants and Regional Support Centers Mitigation of Loss of Spent Fuel Pool Cooling, includes Diverse Instrumentation (Tier 1) Reliable & Accessible BWR Containment Hardened Vents (Tier 1) Mitigation of Large Fires & Explosions (Security Related) (Tier 1) PLUS Seismic & Flooding Walk-downs (Tier 1) Process for Identifying & Assessing Impact of New Information (Tier 3) EP Communications & Multi-Unit Staffing (Tier 1) 7

8 FLEX Elements Both plant and FLEX equipment that provides means of obtaining power and water to maintain or restore key safety functions for all reactors at a site 8 This includes equipment such as pumps, generators, batteries and battery chargers, compressors, hoses, couplings, tools, debris clearing equipment, temporary flood protection equipment and other supporting equipment or tools Reasonable staging and protection of FLEX equipment from BDBEEs applicable to a site The FLEX equipment would be reasonably protected from applicable site-specific severe external events to provide reasonable assurance that N sets of FLEX equipment will remain deployable following such an event

9 FLEX Elements Procedures and guidance to implement FLEX strategies FLEX Support Guidelines (FSG), to the extent possible, will provide pre-planned FLEX strategies for accomplishing specific tasks in support of Emergency Operating Procedures (EOP) and Abnormal Operating Procedures (AOP) functions to improve the capability to cope with beyond-design-basis external events Programmatic controls that assure the continued viability and reliability of the FLEX strategies These controls would establish standards for quality, maintenance, testing of FLEX equipment, configuration management and periodic training of personnel 9

10 FLEX Boundary Conditions Beyond-design-basis external event occurs impacting ALL units at site All reactors on-site initially operating at power, unless site has procedural direction to shut down due to the impending event Each reactor is successfully shut down when required (i.e., all rods inserted, no ATWS) On-site staff is at site administrative minimum shift staffing levels No concurrent events, e.g., no active security threat Personnel on-site are available to support site response Spent fuel in dry storage is outside the scope of FLEX 10

11 Site Staffing Assumptions On-shift personnel resource planning is limited to the minimum complement described in the site Emergency Plan This staffing level is the minimum on-shift complement, such as present during a backshift, weekend or holiday Perform staffing assessments and ensure on-shift personnel assigned emergency plan implementation functions are not assigned responsibilities that would prevent the timely performance of their assigned functions as specified in the emergency plan The staffing assessment should also consider the applicable actions from Station Blackout (SBO) coping strategies 11

12 Site Access Assumptions First 6 hours No site access This duration reflects the time necessary to clear roadway obstructions, use different travel routes, mobilize alternate transportation capabilities (e.g., private resource providers or public sector support), etc hours Limited site access Individuals may access the site by walking, personal vehicle or via alternate transportation capabilities (e.g., private resource providers or public sector support). 24+ hours Improved site access Site access is restored to a near-normal status and/or augmented transportation resources are available to deliver equipment, supplies and large numbers of personnel. 12

13 FLEX Mitigation Strategies FLEX employs a three phase approach: Phase 1 - Initially coping by relying on installed plant equipment Phase 2 - Transition from installed plant equipment to onsite FLEX equipment Phase 3 - Obtain additional capability and redundancy from offsite equipment until power, water, and coolant injection systems are restored Diverse and flexible to enable deployment of the strategies for a range of initiating events and plant conditions 13

14 14 FLEX Assessment Process

15 Step 1 Baseline Coping Capability Establish a baseline coping capability for Extended Loss of AC Power (ELAP) and Loss of Ultimate Heat Sink (LUHS) Address all three phases of coping. Will require: Enhanced procedures/guidelines Implementing design changes Procurement of equipment Provisions for offsite resources 15

16 FLEX Analysis 16 Plant-specific analyses will determine the duration of each phase Recovery of the damaged plant is beyond the scope of FLEX capabilities as the specific actions and capabilities will be a function of the specific condition of the plant and these conditions cannot be known in advance To the extent practical, generic thermal hydraulic analyses will be developed to support plant-specific decision-making Justification for the duration of each phase will address the onsite availability of equipment, the resources necessary to deploy the equipment consistent with the required timeline, anticipated site conditions following the beyond-design-basis external event, and the ability of the local infrastructure to enable delivery of equipment and resources from off-site

17 17 Use MAAP to Evaluate Extended SBO Scenario

18 Use MAAP to Identify Capabilities for Extended and Phase 1-2 Transition SBO with RCIC Operating (Torus Suction; Recirc Seal Leak 36 gpm) SRV Depressurize to 150 psig Torus water temperature exceeds 200 F HCL Exceeded; Depressurize RPV to <50 psig; RCIC Tripped Torus water temperature exceeds 230 F RPV level below TAF Core Damage PSP Exceeded Containment PCPL Torus water temperature exceeds 260 F Result: Adequate Core Cooling 6.0 Hours Aggressive Cooldown to 150 psig at <100 F/hr t (Hours) 18 In this representative evaluation, it confirms that the plant coping period for Phase 1 (reliance on installed plant equipment) is 6 hours before core damage starts for an extended SBO

19 Use MAAP to Identify Phase 2 Capabilities SBO with RCIC Operating (Torus Suction; Recirc Seal Leak 36 gpm) SRV Depressurize to 150 psig HCL Exceeded Torus water temperature exceeds 200 F All Alignments of Portable D/G to Battery Chargers & Portable Diesel Fire Pump Completed Torus water temperature exceeds 230 F PSP Exceeded Torus water temperature exceeds 260 F Containment PCPL Result: Adequate Core Cooling >24 Hours RCIC operable for 6.2 hours DC battery life extended to 7 hours based on load shed Portable equipment aligned by 6.2 hours Aggressive Cooldown to 150 psig at <100 F/hr Analysis confirms that the onset of core damage for an extended SBO can be delayed >24 hours by using portable equipment t (Hours)

20 20 BWR Baseline Coping Summary

21 21 PWR Baseline Coping Summary

22 Instrumentation Assessment Actions specified in plant procedures/guidance for loss of ac power are predicated on use of instrumentation and controls powered by station batteries A minimum set of parameters necessary to support FLEX strategy implementation is defined based on maintaining the key safety functions as well as indications of core damage Typically parameters: 22

23 23 FLEX SFP Strategies

24 Electrical Power Strategies Employ 480 VAC Portable Diesel Generators to supply: Two safety related battery chargers Battery Room Ventilation Control Room Lighting and Ventilation Re-power RCS Charging Pump (for boron addition) Employ Multiple 120 / 240 VAC Portable Diesel Generators to supply: Select instrument buses Portable air conditioning or ventilation units Communications equipment and associated battery chargers 4160 VAC Electrical Connection Points: Multiple and redundant connections to Safety Related loads 4160 portable diesel generators provided by Regional Support Centers Back-up strategies will likely involve diversity in connection points (i.e. busses and critical components) 24

25 FLEX Communications Assessment Phase 1 assess capabilities for all specified EP functions Phase 2 assess communication capabilities needed for FLEX Should have methods and capabilities necessary to support simultaneous implementation of any 2 FLEX strategies for each affected unit 25

26 Communications Strategies 26 In-Plant Radios: Pre-defined number of primary and back-up radios Increased battery inventory with SBO charging strategy Plant repeaters with supplemental power capability Satellite Phone system: Pre-defined number of primary and back-up satellite phones Hardened antennas, multiple for redundancy Dedicating one satellite line to a continuous bridge network Satellite phone cradles can be tied into plant switchboard (PBX) Station Public Address Speakers: Battery back-up Ability to be powered from portable 120 VAC generator Sound Powered Phones: Self powered. Link Control Room to several critical field locations.

27 Step 2 External Event Stress Tests Process for identifying potentially applicable hazards: Extreme seismic events, Extreme external flooding, Extreme storms such as hurricanes, high winds, and tornadoes, Extreme snow, ice, and cold, and Extreme heat. Where applicable, each site addresses: Protection of FLEX equipment, Deployment of FLEX equipment, Procedural interfaces, and Utilization of offsite resources. 27

28 28 External Hazards Assessment

29 Step 3 Implementation Plan and Programmatic Controls Provision of at least N+1 sets of portable onsite equipment stored reasonably protected from applicable external events Procedures and guidance to support deployment and implementation Programmatic controls addressing: Quality attributes Equipment design Equipment Storage Maintenance and testing Training Staffing Configuration Controls 29

30 Representative High-level Example (BWR) Phase 1 Initial Coping Capability Use RCIC for RPV makeup from suppression pool Rely on DC Power for key instrumentation and controls Phase 2 Extended Coping Capability Charge battery with portable generators to maintain DC power Provide extended RPV makeup with portable pump Use Reliable Hardened Vent for containment heat removal Phase 3 Extended Coping Capability Use additional offsite equipment from Regional Response Center 30

31 Representative High-level Example (PWR) Phase 1 Initial Coping Capability Turbine-driven AFW for SG makeup from Condensate Storage Tank Rely on DC Power for key instrumentation and controls Phase 2 Extended Coping Capability Charge battery with portable generators to maintain DC power Provide extended SG makeup with portable pump Provide RCS makeup with portable pump Phase 3 Extended Coping Capability Use additional offsite equipment from Regional Response Center 31

32 FSG Overview FSGs are a new group of guidelines for implementing FLEX strategies FSGs typically have a singular function (e.g., repower batteries from portable generator) FSGs do not replace EOPs/SAGs, but are integrated with them FSG hierarchy is for MORE than just the Operator (think about ED, TSC, etc). Existing B.5.b and SAMG strategies may be incorporated into or supplemented by FSGs. 32

33 Overview of Support PWR FLEX Strategy FLEX Strategy 33 Reference ELAP DC Bus Load Shedding / Bus Management Section of NEI 12-06, guideline (6) Loss of DC Power / Essential Indications Table 3-2 of NEI 12-06, Safety Functions for Key Reactor Parameters, Key Containment Parameters and SFP Parameters Alternate Low Pressure Feedwater Source Section of NEI 12-06, guidelines (2), (5) and (13) Alternate Condensate Storage Tank (CST) Makeup Section of NEI 12-06, guideline (5) Alternate RCS Makeup Section of NEI 12-06, guidelines (2), (4) and (13) Alternate Boration / Section of NEI 12-06, guideline (13) Letdown for Subcriticality PA-ASC-0916 analyses FLEX Equipment Staging and Support Activities Section of NEI 12-06, guideline (1) Section of NEI 12-06, guidelines (3), (7), (8), (9), (10) (11), and (15) Long-term Containment Heat Removal Table 3-2 of NEI 12-06, Safety Function for Containment Pressure Control/Heat Removal Alternate SFP Makeup and Cooling Section of NEI 12-06, guideline (14) Cold Leg Accumulators (CLA), Safety Injection Tank (SIT), Core Flood Tank (CFT) Isolation or Venting Table 3-2 of NEI 12-06, Safety Function for Spent Fuel Cooling PA-ASC-0916 analyses

34 Interfacing FSGs with PWR EOPs PWR Emergency Operating Procedures will have pointers/connectors to FSGs to recover loss of function (e.g. TDAFWP) where FSGs support permanently installed equipment. Emergency Operating Procedures always will be the controlling documents

35 PWR EOP-FLEX Interface (Example) FSG-00X Alternate Low Pressure Feedwater Source 35

36 EVENT Is RX Power Less than 10-1% and dropping? PWR - STANDARD POST TRIP ACTION DIAGNOSTIC FLOWCHART YES Does at least one Vital AC & DC Train have power? NO Does at least one Vital DC Train have power? NO GO TO FUNCTIONAL RECOVERY YES YES Is at least one RCP running? NO CONSIDER LOOP / LOFC EOP CONSIDER BLACKOUT EOP YES CONTINUE SPTA DIAGNOSIS 36

37 YES BLACKOUT CONFIRMED SFSC CRITERIA SATISFIED NO NO GO TO Optimal Recovery Procedure GO TO Functional Recovery Procedure PWR - FLEX FLOWPATH FROM BLACKOUT EOP YES Continue in the BLACKOUT EOP: Classify the event Actuate Main Steam Isolation Signal (MSIS) Inform the Energy Control Center Dispatch the area operator to the SBOGs Place Charging Pumps in Pull-to-Lock Minimize RCS leakage Maintain RCS Tc less than 570 o F using ADVs Ensure at least one SG is restoring level to 45-60% NR One vital 4.16 kv bus energized within one hour NO SBOG or EDG Available? NO REFER TO the Extended Loss of AC Power Guideline (FSG) YES YES Continue in the BLACKOUT EOP 37

38 BWR EOP FLEX Interface SBO AOP Event Based Example of Action: Reduce Battery Loads Implemented in parallel EOPs Symptom Based Examples: Portable Generators FSGs Examples: Portable pumps Remote operation of RCIC, HPCI, SRVs 38

39 BWR EOP FLEX Interface Detail A Flooding Systems Group 1: Condensate/Feedwater CRD RCIC RHR Group 2: Maximize flow if necessary (AIP 407). Use manual operation procedure if necessary (SAMP 703). Use HXs as soon as possible. Core Spray RHR Service Water (AIP 401) Fire System (AIP 404) Well Water (AIP 403) GSW (AIP 403) ESW (AIP 402) Condensate Service Water (AIP 405) SBLC (AIP 406) 39 Portable Diesel Fire Pump Use SAMP 708 to inject to the RPV. Use SAMP 711 to inject to the drywell.

40 SAFER (Phase 3) Organization and Response Plan

41 SAFER Organization SAFER Strategic Alliance for FLEX Emergency Response SAFER is an alliance established between AREVA and Pooled Inventory Management (PIM) The SAFER team is contracted by the nuclear industry to establish and operate National SAFER Response Centers (NSRCs) to purchase, store, maintain and deliver emergency response equipment in the case of a major nuclear accident or BDBEE in the US An effective response is dependent on integrated planning and response actions among the nuclear station, SAFER team, governmental authorities and industry & vendor support personnel 41

42 SAFER Facilities Primary and Alternate Facilities Two Facilities in case one is unavailable due to the event SAFER Control Centers (SCC) & National SAFER Response Centers (NSRC) 42

43 SAFER Facilities National SAFER Response Centers (NSRC) Storage and Deployment of Equipment up to 4 Units Duplicate Equipment at Each Response Center Preventive Maintenance and Testing Performed at NSRCs Two Locations Memphis, TN Phoenix, AZ Staffing NSRC is Manned to Perform Maintenance / Testing Activated by the SAFER Control Center (SCC) to Support Deployment 43

44 44 Staging Areas (Selected by the site)

45 Staging Areas Staging Areas Are Determined by the Utility Staging Area A Final Resting (Operational) Place(s) of equipment on-site Staging Area B Staging Area on-site (preferred if NSRC trucks can directly access the site) Staging Area C Primary off-site Staging Area ~= 25 Miles From the Site Staging Area D Optional Off-site Staging Area ~= 25 Miles From the Site 45

46 SAFER Staging Area Sizing Study (~360 x 250 ) The helicopter area may be preferred to be a safe distance from personnel or staging area operations 46

47 SAFER Equipment - Generic Equipment Performance Characteristics # of Units Medium Voltage Generator 4160 V 1 MW 18 Low Voltage Generator 480 V 1100 kw 10 High Pressure Injection Pump 2000 psi 60 gpm 10 SG/RPV Makeup Pump 500 psi 500 gpm 10 Low Pressure / Medium Flow Pump 300 psi 2500 gpm 10 Low Pressure / High Flow Pump 150 psi 5000 gpm 10 Lighting Towers 440,000 lumens (minimum) 30 Diesel Fuel Transfer 500 gallon air-lift container 10 Diesel Fuel Transfer Tank 264 gallon tank, with mounted 10 AC/DC pumps Portable Fuel Transfer Pump 60 gpm after filtration 10 47

48 48 Equipment Medium Voltage Generator in Excess of 2 MW SAFER Equipment Non Generic (1/2) Quantity Purchased 1 Reactor Units Using Equipment for Coping Reactor Units Using Equipment for Defense in Depth 2 NOTES The generic and non-generic 4160V generators are the same in terms of accounting for the total number of 4160V generators needed by a site. Some units may use up to 2 (1 from each NSRC) additional generators (in addition to the generic 4160V generators) for defense in depth. Credit is taken for the generic maintenance spare. 480/600V Step Up Transformer Coping Strategy - Catawba 1 & 2. No allowance for maintenance unavailability is necessary. Each NSRC is capable of supporting 4 reactor units for coping or defense-in-depth, as applicable. Air Compressor 10 ~ ~ Purchased per NSRC (same as Water Treatment 4 4 (2 sites) 59 (34 sites) Generic Equipment) Coping Strategy - Byron 1 & 2 and Braidwood 1 & 2. One water treatment system is capable of providing the water necessary for each site for coping. (90 day Out-Of-Service time applies)

49 Equipment Non Generic (2/2) Equipment Portable Submersible Pump Quantity Purchased 1 Reactor Units Using Equipment for Coping Reactor Units Using Equipment for Defense in Depth 2 NOTES Initially thought to be required for some, this equipment was procured and only a small amount retained (2 at each NSRC) for defensein-depth. Water Storage No allowance for maintenance unavailability is necessary because maintenance is limited to visual inspection for age-related degradation. Each NSRC is capable of supporting 4 reactor units as defense-in-depth. Mobile Boration System 10 ~ ~ Purchased per NSRC (same as Generic Equipment) Ventilation Fan 10 ~ ~ Purchased per NSRC (same as Generic Equipment) Suction Lift Booster Pump 14 ~ ~ A 2 reactor unit site utilizes 3 booster pumps (5000 gpm each): 1 booster pump per 5000 gpm generic pump (2) and shares a single booster pump between both 2500 gpm generic pumps. 2 sites utilize spare per NSRC. 49

50 SAFER Response Plans Site-Specific SAFER Response Plan Chapters 1.Introduction 2.SAFER Control Center 3.National SAFER Response Center 4.Logistics & Transportation 5.Staging Area 6.Site Interface Procedure 7.Equipment Listing Addendum A SAFER Contact list Addendum B Vendor Contact list Addendum C State Contact List Addendum D Event Log Form 50

51 Conclusion 51 FLEX provides an additional layer of Defense-In-Depth for BDB External Events

52 Additional Supporting Slides

53 53 Sample Event Response Time Sequence

54 54 Sample Event Response Time Sequence

55 FLEX On-Site Portable Equipment FLEX S/G Pump FLEX SFP Pump 55 FLEX CST Pump FLEX 480V Diesel Generator

56 FLEX On-Site Portable Equipment F-550 Deployment Vehicle FLEX Debris Removal FLEX Debris Removal 56

57 FLEX On-Site Portable Equipment FLEX Refueling Trailer FLEX Hose Trailers 57

58 58 Defense-In-Depth for Extreme External Events