Safety Evaluation of VHTR Cogeneration System Hiroyuki Sato, Tetsuo Nishihara, Xinglong Yan, Kazuhiko Kunitomi Japan Atomic Energy Agency IAEA International Conference on Non-electric Applications of Nuclear Power 18 April 27 Oarai Japan
JAEA R&D for the VHTR system HTTR 21 23 HTTR-IS system Commercial Commercial VHTR VHTR system system High temperature operation (95 ) : 24 IS Process Continuous hydrogen production 3NL/h 175hr : 25 World s first demonstration of hydrogen production utilizing heat from nuclear power Hydrogen production rate : 8~ Nm 3 /h Hydrogen production for commercial use Economically competitive (2.5 JPY / Nm 3 *) * T. Nishihara et al., Proc. of 15 th International Conference on Nuclear Engineering, ICONE15-1157 (27).
Japanese Design of VHTR Cogeneration system GTHTR3C (17MWth for for H 2 plant) 2 for for Cogeneration of of electricity and hydrogen Electricity generation :: 22MWe Hydrogen production rate :: 2.6MNm 33 /h /h GTHTR3C (37MWth for for H 2 plant) 2 for for Hydrogen production only Hydrogen production rate :: 5.6MNm 33 /h /h Electricity generation for for H 2 plant 2 IS Process Recuperator 9 Generator X. Yan et al., Proc. of 3rd information exchange meeting on nuclear production of hydrogen (25). Precooler 95
Plant Layout of GTHTR3C IS Hydrogen Plant HI Decomposition Facility Bunsen Reaction Facility H 2 SO 4 Decomposition Facility Power Plant 2 nd Loop He Circulator Confinement Isolation Valves Gas & Vessel GTHTR3C Pressure Vessel Heat Exchangers Vessel
Basic Philosophy of GHTHR3C Design Why Non-nuclear grade IS IS process? Open the door to to non-nuclear industries --IS IS process will will be be managed by by oil oil and gas companies Reducing the construction costs of of the IS IS process --Apply the the chemical plant design standard to to the the IS IS process Nuclear grade IS Process Non-nuclear grade Recuperator Generator Precooler
Non-nuclear Design for IS process Safety philosophy for non-nuclear grade IS process* Exempt the IS process from Prevention system 3 (PS-3) Identify the abnormal events initiated in IS process as external events R&D for non-nuclear grade IS process *K. Ohashi, et. Al., J. Atom. Energ. Soc. Jpn., Vol.6, No.1 (27) IS process b. c. a. Non-nuclear grade d. Nuclear grade facility a. Establishment of IS process thermal load disturbance absorption method b. Countermeasure for H 2 explosion c. Countermeasure for toxic gas inflow to reactor control room d. Reduction of tritium releasing to environment & mixing to product H 2
Loss of IS process Thermal Load Process apparatus Process apparatus failure e.g. Pump trip, Leakage Chemical reactor 2 nd He gas system Loss of chemical reaction Outlet temperature increase inlet temperature increase Turbo machine trip Primary System scram Countermeasure for loss of the IS process thermal load is required
Operational Sequence for GTHTR3C To H 2 Plant From H 2 Plant Decrease of H 2 plant load inlet temperature increase CV3 ~ Actuation of CV3 CV1 CV2 inlet temperature drop inlet flow rate variation Precooler V4 Recuperator Core flow rate decrease Power generation variation CV1 : bypass flow control valve CV2 : Recuperator inlet temperature control valve Actuation of CV1 CV3 : inlet temperature control valve V4 : bypass valve inlet temperature control power control Power generation rate control
Dynamic Simulation Code for GTHTR3C Recuperator core VCS Flow Diagram of the Analytical Model of GTHTR3C CV3 CV2 CV1 Pre-cooler Thermal-hydraulic model Non-condensable gas model Field equations Mass continuity, Momentum conservation, Energy conservation Heat transfer correlation equation Experimental equation, Conventional equation Component model Gas Control system kinetics Point nuclear kinetic equation kinetics data
Dynamic Calculation (1/2) - Loss of thermal load of H 2 Plant (17MW) in GTHTR3C - To H 2 Plant Precooler From H 2 Plant CV1 CV3 V4 CV2 CV1 : bypass flow control valve Recuperator CV2 : Recuperator inlet temperature control valve CV3 : inlet temperature control valve V4 : bypass valve ~ secondary inlet helium gas inlet helium gas rotational speed [rpm] 14 12 8 6 12 115 11 15 361 36 359 358 357 356 19 K 5 rpm 1 8 6 4 2 2 4 6 8 Elapsed Elapsed time time from from loss of the IS loss process of H2 thermal plant load load [s] [s] 1 8 6 4 2 CV3 flow rate [kg/s] CV1 flow rate [kg/s]
Dynamic Calculation (2/2) - Loss of Thermal Load of H 2 Plant (17MW) in GTHTR3C - To H 2 Plant Precooler From H 2 Plant CV1 CV3 V4 CV2 CV1 : bypass flow control valve Recuperator CV2 : Recuperator inlet temperature control valve CV3 : inlet temperature control valve V4 : bypass valve ~ Heat transfer quantity [MW] inlet flow rate [kg/s] outlet 5 4 3 2 1 38 36 34 32 3 28 15 5 5MW 15MW 1MW Pre cooler 65 6 55 5 45 4 35 2 4 6 8 Elapsed Elapsed time time from from loss of the IS loss process of H2 thermal plant load load [s] [s] power [MW]
Concluding Remarks JAEA started the R&D for the safety design of commercial VHTR systems GTHTR3C Dynamic simulation models of GTHTR3C was developed Loss of the H 2 plant thermal load can be absorbed by the operational sequence Thanks for your attention. sato.hiroyuki9@jaea.go.jp
Back ground information
Analytical model of heat transfer correlation (Shell side). 8 Nu = C1Re Pr Nu = C2Re Pr. 4. 6. 3 (8<Re<7) (Re>7) (Tube side) ( 5 / 6 ) Pr. 615 Nu. 223Re di 1+. 6 2. 5 ( 1/ 6 Pr. 57 (Re di ) = ) C 1,C 2 : Design Coefficient
Dynamic Calculation (3/4) - Loss of Thermal Load of H 2 Plant (37MW) in GTHTR3C - To H 2 Plant Precooler From H 2 Plant CV1 CV3 V4 CV2 CV1 : bypass flow control valve Recuperator CV2 : Recuperator inlet temperature control valve CV3 : inlet temperature control valve V4 : bypass valve ~ secondary inlet helium gas inlet helium gas Rotational speed [rpm] 14 12 8 6 15 5 44 43 42 41 4 39 38 2 15 1 5 2 4 6 8 Elapsed time from loss of H2 plant load [s] 1 8 6 4 2 CV3 flow rate [kg/s] CV1 flow rate [kg/s]
Dynamic Calculation (4/4) - Loss of Thermal Load of H 2 Plant (37MW) in GTHTR3C - To H 2 Plant Precooler From H 2 Plant CV1 CV3 V4 CV2 CV1 : bypass flow control valve Recuperator CV2 : Recuperator inlet temperature control valve CV3 : inlet temperature control valve V4 : bypass valve ~ Pre cooler heat tranfer quantity [MW] flow inlet [kg/s] outlet 5 4 3 2 1 5 45 4 35 3 25 15 5 Pre cooler 4 2-2 -4 7 6 5 4 3 2 1 2 4 6 8 Elapsed time from loss of H2 plant load [s] heat transfer quantity [MW] power [MW]
Dynamic calculation (4/4) - Loss of thermal load of H 2 Plant (37MW) in GTHTR3C - helium gas pressure [MPa] flow inlet [kg/s] outlet 5.5 5 4.5 4 5 45 4 35 3 25 15 5 Secondary Primary 2 4 6 8 Elapsed time from loss of H2 plant load [s] 5 4 3 2 1 7 6 5 4 3 2 1 Pressure ratio power [MW] pressure difference MAX MAX :: +.16 +.16MPa inlet inlet flow flow rate rate variation ::-59.7-59.7 kg/s kg/s power power variation ::-293-293 MW MW outlet outlet temperature :: Constant
Dynamic calculation (1/4) - Loss of thermal load of H 2 Plant (17MW) in GTHTR3C - secondary inlet helium gas inlet helium gas 14 12 8 6 12 115 11 15 1 8 6 4 2 CV3 flow rate [kg/s] Thermal disturbance 2nd 2nd inlet inlet :: +4 +4 K Inlet Inlet :: +19.7 +19.7 K rotational speed [rpm] 361 36 359 358 357 356 2 4 6 8 Elapsed time from loss of H2 plant load [s] 1 8 6 4 2 CV1 flow rate [kg/s] R.P.M. R.P.M. increase :: + 5 r.p.m. r.p.m.
Dynamic calculation (2/4) - Loss of thermal load of H 2 Plant (17MW) in GTHTR3C - helium gas pressure [MPa] inlet flow rate [kg/s] outlet 5.4 5.2 5 4.8 4.6 4.4 38 36 34 32 3 28 15 5 Secondary Primary 2 4 6 8 Elapsed time from loss of H2 plant load [s] 1 8 6 4 2 65 6 55 5 45 4 35 Pressure ratio power [MW] pressure difference MAX MAX :: +.19 +.19 MPa MPa inlet inlet flow flow rate rate variation ::-34. -34. kg/s kg/s power power variation ::-93.5-93.5 MW MW outlet outlet temperature :: Constant
Dynamic calculation (3/4) - Loss of thermal load of H 2 Plant (37MW) in GTHTR3C - secondary inlet helium gas inlet helium gas 14 12 8 6 125 12 115 11 15 2 15 1 5 CV3 flow rate [kg/s] Thermal disturbance 2nd 2nd inlet inlet :: +4 +4 K Inlet Inlet :: +21 +21 K Rotational speed [rpm] 44 43 42 41 4 39 38 2 4 6 8 Elapsed time from loss of H2 plant load [s] 1 8 6 4 2 CV1 flow rate [kg/s] R.P.M. R.P.M. increase :: + 9 9 r.p.m. r.p.m.