Verification of the Kuosheng BWR/6 TRACE Model with Load Rejection Startup Test Kuan-Yuan Lin, Chunkuan Shih Institute of Nuclear Engineering and Science National Tsing-Hua University, TAIWAN Jong-Rong Wang, Hao-Tzu Lin Atomic Energy Council, R.O.C., TAIWAN 1
2 Outline Introduction Kuosheng TRACE Model Test Description and Results Discussions Sensitivity Study Animation of TRACE Model Conclusions
3 Introduction Its nuclear steam supply system is a type of BWR/6, designed and built by GE on a twin unit concept. The original designed rated power is 2894MWt, and the operating power now is 2943 MWt.
4 Introduction TRACE (TRAC/RELAP Advanced Computational Engine) is a best estimate reactor systems code for analyzing thermal-hydraulic behavior in light water reactors SNAP (Symbolic Nuclear Analysis Package) consists of a suite of integrated applications to simplify the thermalhydraulic analysis. SNAP provides a highly flexible framework for creating and editing input for engineering analysis codes as well as extensive functionality for submitting, monitoring, and interacting with the codes.
Configuration Tool 5 Introduction Model Editor Job Status
6 Kuosheng TRACE Model This TRACE Model consists of 77 hydraulic components 184 control blocks, 82 heat structures 1 power component. Recirculation loop consists of : JetPump recirculation pump pipe We used one bypass valve to simulate the actual six bypass valve. The flow rate is 35% of steam flow rate. Turbine and Condenser are simulated by break component for a fixed boundary condition. Feedwater is simulated by two fill components.
7 Kuosheng TRACE Model 3D view 4 radial rings 2 azimuthal sectors 11 axial levels
8 Kuosheng TRACE Model Fuel 6 channel components (total 624 bundles) 10 cells and 6 radial nodes in 1 channel
9 Test description The Startup Test we chosen to verify the Kuosheng TRACE mode is 100% Power Rejection. This test was conducted on November 11 th,1981, the operator trigger the Breaker to activate the test procedure. The closure of turbine control valve (TCV) caused the reactor scram and bypass valve opened in subsequent. All the analysis results were compared with startup test data. Table 1 Initial value 100 % Power Load Rejection Parameter Test Data TRACE Error(%) Power (MW) 2894 2894 0 Steam Dome Pressure (Mpa) 6.964 6.9639-0.0014 Feedwater Flow (kg/s) 1549.927 1576.391 1.7 Steam Flow (kg/s) 1510.918 1576.391 4.3 NRWL (m) 0.9 0.896-0.44 Core flow (kg/s) 10695.72 10660.19-0.33
10 Result and Discussions Table 2 Sequence of Events for 100 % Power Load Rejection Event(sec) Test TRACE TCV close and BPV open 0 0 BPV Start to Open 0.19 0.19 TCV Start to Close 0.2 0.2 Reactor Scram 0.236 0.305 BPV Fully Open 0.329 0.329 TCV Fully Close 0.394 0.394 Water Level Reach L3 2.2 2.58 Steam Dome Pressure Peak High 3.9(7.426Mpa) 2.5(7.254Mpa) BPV Reset at 940.7 16.3 9.8 End of Analysis - 20
11 Result and Discussions The simulation of power uses point kinetics Scram signal: TCV closure larger than 5%
12 Result and Discussions Initially, the rise of steam dome pressure was caused from TCV closure. The analysis results of steam dome pressure in TRACE were decreased rapidly than Test Data.
13 Result and Discussions The feedwater control system depends on (1)NRWL (2) feedwater flow (3) steam flow. At the beginning, feedwater flow decreased due to the increased of steam dome pressure. After that, the flow rate start to increase because of lower water level.
14 Result and Discussions The trend of TRACE is roughly similar with the test data.
15 Result and Discussions The trends of two curves are generally consistent in the NRWL.
16 Result and Discussions Because of steam dome pressure in TRACE was decreased rapidly than the test data, turbine bypass valve reset earlier than the test data which the set point is 6.55 MPa.
17 Sensitivity Study In sensitivity, we let scram time delay 0.1s, 0.3s and 0.6s respectively. The scram time influenced the maximum of dome pressure and the reset time of BPV.
18 Animation of TRACE Model
19 Conclusions The Kuosheng BWR/6 NPP TRACE model was successfully established by using TRACE code. The verified results of TRACE model reveal the respectable accuracy of the analyses of the 100% power load rejection. The animation mode of Kuosheng TRACE model also has been established by using SNAP.
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