Analysis of the heat exchanger tube rupture accident in the XT-ADS reactor with the SIMMER-III code

Transcription

1 Analysis of the heat exchanger tube rupture accident in the XT-ADS reactor with the SIMMER-III code Abstract ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1 1

2 Introduction XT-ADS design and operating conditions Figure 1: HX design and its arrangement in the primary system of XT-ADS reactor INLET m 1 m ISOLATION VALVES INLET OUTLET ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1

3 Table 1: Main XT-ADS operating parameters Parameter Unit Value Core power at BOL MW 7 LBE cold temperature C 3 LBE hot temperature C 39 Core mass flow rate kg/s 77 Core bypass mass flow rate kg/s LBE mass flow rate in one HX kg/s 1 75 Feedwater pressure bar 3.3 Feedwater temperature C 33 Secondary pressure at HX outlet bar 9.7 Equilibrium quality at HX outlet. SIMMER-III simulation of postulated accidents ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1 3

4 Figure : XT-ADS model used in the SIMMER-III transient analysis a) Primary system b) Safety valves and lines Safety valves Reactor cover SV lines Cover gas HX Pump Hot plenum c) HX and pump compartment By-pass Core Cold zone Tube Break Cold plenum ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1

5 HX water inventory by RELAP5 code Table : HX water inventory Component Volume Mean void Liquid Steam Total H O [m 3 ] fraction mass [kg] mass [kg] mass [kg] Inlet pipe Cold collector Tube bundle Hot collector + tube outlet Total Cover gas circuit and safety valve simulation Table 3: Main cover gas circuit and safety valve parameters Parameter Unit Value Safety valves number Opening pressure set-point bar Valve cross-flow area m.39 Valve capacity (saturated steam) kg/s Inner diameter of line to SV M.15 Length of line to SV above reactor cover M 1 In-vessel cover gas volume m 3 3 Cover gas pressure bar 1 Out-of-vessel cover gas circuit volume Neglected ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1 5

6 Analysis of accident scenarios Table : Break characteristics in the analysed HX tube rupture events Event Single tube rupture Multiple tube rupture Break type Guillotine break of 1 tube at the inlet Guillotine break of 5 tubes at the inlet Diameter [m] Flow area [m ] Initial leakage flow rate [kg/s].3 (by RELAP5 [1]) 11.5 (by RELAP5 [1]) Single tube rupture ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1

7 Flowrate (kg/s) Mass (kg) ANALYSIS OF THE HEAT EXCHANGER TUBE RUPTURE ACCIDENT IN THE XT-ADS REACTOR WITH THE SIMMER-III CODE Figure 3: Material fractions and gas velocity field during the transient phase a) t = s (1 s after break opening) b) t = 3 s (1 s after SV opening) Figure : Main results of the single tube rupture simulation 5 a) Break flowrate and cumulated value b) Cover gas pressure 1 HO flowrate Cumulated value 3 1 SV1 inlet SV inlet In-vessel c) HX secondary pressure d) HX Pump compartment pressure 1 9. Tube inlet Tube bundle pump comp. HX bundle 9.. ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD e) Steam release through safety valves f) Active core voiding 1..

8 Flowrate (kg/s) Flowrate (kg/s) Mass (kg) Void fraction (%) 3 1 ANALYSIS OF THE HEAT EXCHANGER TUBE RUPTURE ACCIDENT IN THE XT-ADS REACTOR WITH THE SIMMER-III CODE SV1 inlet SV inlet In-vessel Figure : Main results of the single tube rupture simulation (cont.) c) HX secondary pressure d) HX Pump compartment pressure Tube inlet Tube bundle pump comp. HX bundle e) Steam release through safety valves f) Active core voiding. 1.. SV1 flowrate SV flowrate.3 Active core Multiple tube rupture ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1

9 Flowrate (kg/s) Mass (kg) ANALYSIS OF THE HEAT EXCHANGER TUBE RUPTURE ACCIDENT IN THE XT-ADS REACTOR WITH THE SIMMER-III CODE Figure 5: Material fractions and gas velocity field during the transient phase a) t = s (1 s after break opening) b) t = s (13 s after SV opening) Figure : Main results of the multiple tube rupture simulation a) HX Pump compartment pressure b) Break flowrate and cumulated value pump comp. HX bundle HO flowrate Cumulated value c) HX secondary pressure d) Cover gas pressure 5 15 Tube inlet 1 SV1 inlet Tube bundle SV inlet 5 In-vessel ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD e) Steam release through safety valves f) Active core voiding.3

10 Flowrate (kg/s) Void fraction (%) Flowrate (kg/s) Mass (kg) HO flowrate ANALYSIS OF THE HEAT EXCHANGER TUBE RUPTURE ACCIDENT IN THE XT-ADS REACTOR WITH THE SIMMER-III CODE Cumulated value Figure : Main results of the multiple tube rupture simulation (cont.) c) HX secondary pressure d) Cover gas pressure Tube inlet Tube bundle SV1 inlet SV inlet In-vessel e) Steam release through safety valves f) Active core voiding Active core. 3 1 SV1 flowrate SV flowrate Conclusions 1 ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1

11 References ACTINIDE AND FISSION PRODUCT PARTITIONING AND TRANSMUTATION, ISBN , OECD 1 11