Life Extension Testing of Electrical Penetration Assemblies

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1 Nuclear Division Life Extension Testing of Electrical Penetration Assemblies EQ Conference Oct 31 Nov 2, 2018 Steve Benesh, Curtiss-Wright Nuclear 1 October 22, 2018 Curtiss-Wright

2 Summary Life Extension Testing of EPAs Qualification Standards and Scope Testing Strategies Challenges Test Design Results 2 Feb, 2017 Proprietary 2014 Curtiss-Wright

3 Qualification Scope and Standards Qualification Standards: IEEE IEEE standard for Electric Penetration Assemblies in Containment Structures for Nuclear Power Generating Stations. Customer s implementing procedures/standards - follows IEEE 317 Qualification Scope Qualified-life testing for 24 EPA modules per above standards and customer approved test procedure including: o Initial tests continuity, IR, dielectric withstand, gas leak rate and visual o Pre-conditioning shipping and storage simulation, thermal cycling, thermal aging and radiation aging. o Short-circuit current and short-circuit thermal capacity tests o Seismic was not required by customer o DBE Simulations o Rated short-time overload current and duration during DBE environmental conditions o Rated short-circuit current and thermal capacity tests during DBE environmental conditions 3 Feb, 2017 Proprietary 2014 Curtiss-Wright

4 Testing Strategies Laboratory tests were designed to simulate the as installed configuration and minimize over-testing: DBE tests simulated EPA installation on the outboard end of the penetration nozzle. Prior to DBE simulations we performed trials with dummy specimens to set test LOCA system parameters (i.e. superheat temp, pressure regulators, etc.) to ensure minimal overshoot. Modules were aged in Nitrogen to maintain 2% to 10% Oxygen atmosphere along with a high humidity environment. Continuous current and fault current tests were based on the actual maximum current that could occur in the plant. Voltages were based on maximum actual voltage in the plant Pre-planning of test fixtures, resources and testing approach to meet customer schedule: Multiple test flanges that mimic the field configuration for gas leak rate testing Multiple DBE accident test chambers to allow for parallel testing Project staffed to meet customer schedule Test approach to gather required data for qualification in an efficient manner Test specimen selection Stock (inventory) samples and Field installed samples 4 Feb, 2017 Proprietary 2014 Curtiss-Wright

5 Challenges Challenges: Customer had compressed schedule how to reduce overall qualification time: 24 EPA modules under test, ~ 1800 conductors 18AWG-150C, 16 AWG-140C, 10 AWG -75C, 8 AWG-27C, 2/0 AWG-7C and Coaxial Thermal Aging for 60 years, acceleration factor 250, ~3 months aging time Four groups of modules with different radiation aging requirements, ~3 months aging time 2 customers, different DBE profiles H4 (LOCA), H5 (Severe Accident), Post-Fukushima (FOSH) Different profiles for Wet Well versus Lower Drywell modules Forsmark H4 and H5 DBEs were 30 days Large number conductors (150 to 350) to monitor during DBE Testing How to measure Insulation Resistance, Voltage & Current during DBE simulation Customer wanted modules aged in Nitrogen (maintaining a 2%-10% oxygen level) since containments are inert with Nitrogen during operation. Test specimens were to be aged for 20 days with 95% RH. Internal EPA module volumes, which is a variable in calculating leak rates by pressure decay method, were not known. 5 Feb, 2017 Proprietary 2014 Curtiss-Wright

6 Initial Electrical Testing IR, Dielectric, continuity and resistance testing. Used containers with copper BBs to test conductors to all other conductors. 6 Feb, 2017 Proprietary 2014 Curtiss-Wright

7 Gas leak rate testing by pressure decay method 3 EPA Header Plate Flanges fabricated with 6 feedthrough ports each. Test flange ports designed with same dimensions as ports in EPA header plates in the plant. Each port had individual monitoring connection for leak rate measurement of individual modules. Manifold to pressurize and leak test 6 modules at a time. 7 Feb, 2017 Proprietary 2014 Curtiss-Wright

Determining internal volume of EPA modules Gas leak rate by pressure decay was most efficient method for determining leak rate in acceptance range

Determined internal volume of modules by pressuring a known gas volume and releasing the pressure to the module internal space.

8 Determining internal volume of EPA modules Gas leak rate by pressure decay was most efficient method for determining leak rate in acceptance range <1E-3 cm 3 /sec. Internal volume of modules were unknown and needed to be determined to calculate module leak rate by pressure decay method. Determined internal volume of modules by pressuring a known gas volume and releasing the pressure to the module internal space. Knowing the initial and final pressure we could calculate the internal volume of each type of module using the ideal gas laws. 8 Feb, 2017 Proprietary 2014 Curtiss-Wright

9 Thermal Aging in Nitrogen Oxygen sample Thermocouples Modules in Thermal Aging Oven 9 Feb, 2017 Proprietary 2014 Curtiss-Wright

10 Thermal Aging in Nitrogen Thermal aging chambers, data acquisition and oxygen concentration analyzer. Sealed chamber and inerted with Nitrogen. 10 Feb, 2017 Proprietary 2014 Curtiss-Wright

Test Chamber Design Designed portable chamber equivalent in size to the containment nozzle Three portable extension chambers that mount directly to the CWN LOCA chamber were fabricated.

11 Test Chamber Design Designed portable chamber equivalent in size to the containment nozzle Three portable extension chambers that mount directly to the CWN LOCA chamber were fabricated. Chambers had immersion heater and temperature and pressure control system. Ports at the end of the nozzle allowed conductors to exit for electrical testing during the DBE simulation. Chamber was insulated Advantages: After the ramp and once the profile reached saturation or submergence conditions, chamber could be disconnected from LOCA system, blind flange added to back of chamber and remaining profile completed away from the LOCA chamber. LOCA system available to start the next accident simulation typically within 1 to two days vs. being tied up for the full 30 day test. Significant time savings during DBE testing. Immersion heater and compressed air/nitrogen supply able to accurately maintain profile temperature and pressure conditions. Temperature conditions during ramp and first couple plateaus were representative of conditions that the EPA would see in the plant with EPA installed on the outboard side of the nozzle. Temperature control with immersion heater and regulated pressure source provided tight temperature and pressure control. Chemical waste during submergence was significantly less than would be needed for large chamber. Conservatisms Chamber was insulated so that nozzle did not conduct heat as wells as nozzles in the containment structure. Testing did not take any credit for junction boxes that are installed in the containment and that would have provided an additional steam barrier during the DBE. 11 Feb, 2017 Proprietary 2014 Curtiss-Wright

12 Test Chamber Design Nozzle/ Extension Chamber Conductors exiting chamber. LOCA Chamber EPA 12 Feb, 2017 Proprietary 2014 Curtiss-Wright

13 Nozzle Extension Chamber 13 Feb, 2017 Proprietary 2014 Curtiss-Wright

14 DBE Trails Prior to performing the DBE Simulation with the test specimens, Technicians would perform several trials with dummy specimens or equivalent heat sink in the accident chamber to determine settings for superheat temperatures, over-boarding pressure, valve settings and etc. 14 Feb, 2017 Proprietary 2014 Curtiss-Wright

15 LOCA Chamber vs. Module Temperature plot Initially ~ 40 C to 50 C temperature difference from entrance to nozzle and at EPA flange on outboard end of nozzle. After about ~2 hrs. temperatures converged. Temperature in LOCA System Chamber Temperature in nozzle between modules in EPA flange 15 Feb, 2017 Proprietary 2014 Curtiss-Wright

16 Electrical Testing during H4 (LOCA) DBE Simulation Difficulties with IR testing: Customer wanted to capture insulation resistance (IR) readings on all conductors and specifically at the higher temperatures during the initial temperature plateaus. The first temperature plateau was 1 minute long and second was 10 minutes long. Tests had 150 to 350 conductors After taking IR readings needed to quickly transition to loading conductors with voltage and current. Test Set-up: Conductors inside the LOCA chamber were laid onto a grounded metal plate during LOCA testing to ensure a good ground plane. Conductors were wired in series for voltage and current. Conductors were broken down in groups of 20 or 30 conductors for IR testing. Voltage was applied to each group of conductors and insulation resistance measured. Single wire measurement was taken on each module for reference. Expected IR for the group if all conductors had the same insulation resistance as the single wire would be: 16 Feb, 2017 Proprietary 2014 Curtiss-Wright

17 Insulation Resistance Measurements IR Test Set-up Electrical Loading Voltage & Current 17 Feb, 2017 Proprietary 2014 Curtiss-Wright

18 Testing Strategies IR testing of conductor groups via Hipot testers 18 Feb, 2017 Proprietary 2014 Curtiss-Wright

19 Qualification Results Program started with the testing of 18 EPA modules from stock (inventory). Testing was extended to test an additional 6 modules removed from service at Forsmark Unit #2. Total project testing duration ~12 months. Test results after conditioned for 60 years life: Mechanically Testing results showed that modules generally did well in regards to pressure integrity and leak tightness requirements. Electrical Signal Integrity Some module types showed discontinuities or high resistance measurements during temperature aging and DBE testing. Customer was able to limit the modules requiring replacement based on test results for 40 to 60-year life extension. 19 Feb, 2017 Proprietary 2014 Curtiss-Wright

20 SUMMARY Overall joint project between two utilities provided considerable savings by sharing testing costs, resources and test samples. Position or location specific testing reduced risk of failure due to over-testing that would have occurred with enveloping DBE profiles but did required additional testing time and cost. Testing to the installed configuration with EPA on the outboard end of nozzle and at plant actual maximum currents and voltages reduced risk. Pre-planning with multiple header plate flanges and accident chambers significantly reduced project timeline. Planning of electrical testing method to monitor large quantity of electrical conductors during DBE was an important consideration including finding a suitable instrument that could measure lower IR values with grouped conductors. Standard IEC provided helpful information in regards to IR measurements during LOCA testing to avoid uncertainties during the test. Test approach resulted in limiting modules requiring replacement for plant life extension but did identify some electrical issues with certain module types. 20 Feb, 2017 Proprietary 2014 Curtiss-Wright

21 21 Feb, 2017 Proprietary 2014 Curtiss-Wright

22 Nuclear Division QualTech NP Thank You 22 October 22, 2018 Curtiss-Wright

Aug07 Rev A All Paragraphs Revised

Qualification Test Report Universal MATE-N-LOK* Connector 110-213 28Aug07 Rev A All Paragraphs Revised 1. INTRODUCTION 1.1. Purpose 1.2. Scope Testing was performed on Universal MATE-N-LOK* connectors