Passive Heat Removal System Testing Supporting the Modular HTGR Safety Basis

Transcription

1 Passive Heat Removal System Testing Supporting the Modular HTGR Safety Basis Various U.S. Facilities Office of Nuclear Energy U.S. Department of Energy Jim Kinsey Idaho National Laboratory IAEA Technical Meeting April 9, 2014

2 Passive Heat Removal System Testing Activities The capability to remove reactor core residual heat by passive and inherent means is a key to the safety basis for the modular HTGR design concept. The U.S. NRC s Policy Statement on Advanced Reactors provides an expectation that advanced reactors will provide enhanced margins of safety, including use of: Highly reliable and less complex shutdown and decay heat removal systems. The use of inherent or passive means to accomplish this objective is encouraged (negative temperature coefficient, natural circulation, etc.). The U.S. Department of Energy is supporting the testing of passive heat removal systems and concepts at the following facilities Argonne National Laboratory Oregon State University Texas A&M University University of Idaho University of Wisconsin Madison 2

3 NSTF at Argonne The Natural Convection Shutdown Heat Removal Test Facility (NSTF) has been developed at Argonne to support the ARC, SMR, and NGNP programs NSTF objectives are to 1. examine passive safety features for future nuclear reactors 2. provide a user facility to explore alternative concepts 3. generate benchmark data for code V&V 3

4 Project Scope and Reach Design and scaling based off a high temperature, gas reactor concept Simplistic, ex-vessel design provides cross-cutting opportunities Heat flux alone off RPV serves as the mode of heat transfer Concurrent with a broader purpose including several NEUPs at multiple universities, CFD modeling, and 1D systems analysis Experimental efforts at multiple scales, using both air and water 4

5 High Resolution Instruments Fully integrated control suite fed by nearly 500 data acquisition channels 220 kw distributed across 40 control zones for prototypic power profiling High density temperature fields via LUNA optic fiber cables 82-m total length with 4mm resolution at 0.1 Hz (120,000+ data points / minute) Radiative / Conv. heat flux Power control substation Metrological weather Flow / pressure 5

6 Test Parameters 1) Scaling law tests a) Heat flux variations (flat profile vs. cosine distribution, maximum heat flux [10 kw/m 2 full scale] vs. 50% heat flux vs. 25% heat flux) b) Variation of heated zone length (¼ scale, ½ scale [22 ft]) c) Pressure drop tests (introduce different size orifices downstream of tube bank) d) Variation of atmosphere discharge height (¼ scale, ½ scale [84 ft]) e) Vary tube bank setback from heated wall (min. distance [16 in], max. distance [42 in]) 2) GA-MHTGR accident scenarios a) Axial profile, steady state tests b) Time history tests (PCC, DCC) c) Power skew tests (steady state, transient) Radial power profile Skewed tube orientation (to mock up silo corner configuration) Other parametric variations Startup procedures Weather conditions (Chicago winter and summer) Blocked tube, chimney configurations 6

7 Current Testing Status Facility design, fabrication and initial demonstration testing completed in FY13. FY14 work includes a battery of tests to examine RCCS performance under both normal and accident conditions, as well as scaling tests to verify scalability to plant conditions. Baseline accident scenario Variations in physical scale Prototypical power history Variations in heated profile Investigatory test conditions Start-up procedure variations Spring Summer Fall Winter 7

8 The OSU High Temperature Test Facility High Temperature Test Facility Vessel ¼ length scale 6.1 meters tall. ¼ diameter scale 1.92 meters vessel outside diameter. Material Stainless steel (SS304). ASME pressure rating of 9.65 bar at 550ºC. Pressure scale of facility 1:8.0 at 8.0 bar. Upper and lower heads utilize an inner ceramic liner. The lower head provides for instrument taps and penetration of the electric heater rods. Prismatic block core.

9 HTTF Fabrication

10 Core Stack

11 Matrix Tests Test Plan Double Ended Inlet-Outlet Crossover Duct Break Control Rod Drive Nozzle Break Inlet Crossover Duct Break Double Ended Inlet-Outlet Crossover Duct Break with Failure of one train of RCCS Complete Loss of Flow Complete Loss of Flow with Failure of one train of RCCS Outlet Crossover Duct Break Inlet Plenum Mixing Outlet Plenum Mixing (2)

12 Water-RCCS 12 Water-RCCS

13 AIR-COOLED RCCS 13 Left Exhaust Pipe (1 unit) Left Exhaust Pipe Flange (2 unit) Upper Plenum Windows Top, Front, Rear (1 unit each) Upper Plenum Left Plate (1 unit) Risers Support Plate (1 unit) Blower (4 units) Right Exhaust Pipe (1 unit) Right Exhaust Pipe Flanges (2 unit) Upper Plenum Right Plate (1 unit) Upper Plenum Bottom Plate (1 unit) Riser (1 unit) Heater (4 units)

14 Air RCCS CFD Simulations SolidWorks 2013 STAR-CCM+ (Version ) Linux Workstation (AMD 8 core / 4GHz)

15 RCCS Model Full Natural Circulation Area of high velocity requires further analysis. (Why would velocity peak here?) ~ 2.36 m/s duct outlet (predicted) mid-plane Heat Flux Profile q max = 1.68 kw/m m/s inlet boundary (predicted) The ~2.36 m/s duct outlet velocity predicted by the STAR-CCM+ simulation, also was predicted by the Fluent simulation (NURETH paper).

16 UW-Madison Air RCCS Facility The RCCS at UW-Madison is a ¼ scale facility. Construction has been completed and testing is being conducted. The ¼ scale facility has 6 standpipes and has a total height of 13 m. 16

17 UW-Madison Air RCCS Facility 17 Test Section Exhaust Piping Experiment Silo 32 electrical resistance heaters simulate decay heat from the reactor pressure vessel. Maximum power of the facility is 40 kw and a maximum peak heat flux of 20 kw/m 2. Final results gathered will be compared to those at different scaled facilities (Argonne National Lab and Texas A&M).