current status of research and development on system ... system integration technology for...
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Current Status of Research and Development on System Integration Technology for Connection between HTGR and Hydrogen Production System
at JAEA
Hirofumi Ohashi, Yoshitomo Inaba, Tetsuo Nishihara,
Tetsuaki Takeda, Koji Hayashi and Yoshiyuki Inagaki
Japan Atomic Energy Agency, Japan
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Contents
Concept of the HTGR hydrogen production system
R&D items on the system integration technology
Control technology to keep reactor operation against thermal disturbance caused by the hydrogen production system
Estimation of tritium permeation from reactor to hydrogen
Development of a high-temperature isolation valveto separate reactor and the hydrogen production system in accidents
Conclusion
Countermeasure against explosion of combustible gas
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HTGR Hydrogen Production System
Isolation valve
Concept of the HTGR Hydrogen Production System
Chemical reactorSecondary heliumhot gas duct
Intermediate heat exchanger (IHX)
Reactor
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IHX Chemicalreactor
Primary He gas Secondary He gas Process gas
Raw material
Hydrogen
Reactor
R&D Items on System Integration Technology
IHX ChemicalreactorReactor
Control technology to keep reactor operation against thermal disturbance caused by the hydrogen production system
IHX ChemicalreactorReactor IHX ChemicalreactorReactor
Reactor scram
Estimation of tritium permeation from reactor to hydrogen
IHX Chemicalreactor
Raw material
Hydrogen
Reactor
Control technology to keep reactor operation against thermal disturbance caused by the hydrogen production system
TritiumTritium
Hydrogen
Countermeasure against explosion of combustible gas
Estimation of tritium permeation from reactor to hydrogen
IHX Chemicalreactor
Raw material
Hydrogen
Reactor
ExplosionBlast
IHX Chemicalreactor
Raw material
Hydrogen
Reactor
Isolation valve
Countermeasure against explosion of combustible gas
Development of a high-temperature isolation valve to separate reactor and the hydrogen production system in accidents
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Control Technology (1/3)
ObjectiveDevelopment of the control technology to keep reactor operation against thermal disturbance caused by the hydrogen production system.
ApproachJAEA proposed to use a steam generator (SG) as the thermal absorber which
is installed downstream the chemical reactor in the secondary helium gas loop.In the HTTR hydrogen production system, target value of the mitigation for the
helium gas temperature fluctuation is within 10 oC at SG outlet.
Simulation test on the loss of chemical reaction was carried out using a mock-up test facility
Primary He gas Secondary He gas Process gas
Raw material
Hydrogen
IHX SGReactorChemicalreactor
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Control Technology (2/3)Simulation test on loss of chemical reactionMock-up test facility
880oC
LN2 tank
LNG tank
Water tank
Radiator
Steam generator
Chemical Reactor(Steam reformer)
Electric heaterCirculator
Flare stack
Hot gas ductHelium gas circulation loop
Nitrogen feed line
Natural gas feed line
Steam feed line
600oC
CH4+H2O3H2+CO
450oC
650oC
Steam generator
Electric heater
Helium gas circulator
Chemical reactor
Flare stack
Steam generator (SG)
With electrical heater instead of IHX of HTTR
Helium gas temperature and pressure at the chemical reactor inlet (880oC, 4MPa) are same as those of the HTTR hydrogen production system.
4MPaSteam reforming of methane is used instead of the IS process.
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Control Technology (3/3)Simulation test on loss of chemical reactionProcedure
The supply of the raw gas for the hydrogen production, methane, was suspended during the normal operation.
Radiator
SG
NitrogenNaturalCirculation
Helium gas（840oC, 4MPa）
Loss of chemical reaction
Chemical reactor
Feed water
Chemical reactor
Helium gas（840oC, 4MPa）
SG
Raw gasHydrogen
Radiator
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400
600
800
1000
-1 0 1 2 3 4 5 6
Experimental result
The fluctuation of the helium gas temperature could be mitigated at SG outlet within the target range of 10 oC.
Elapsed time [h]
SG outlet
SG inlet
Chemical reactor inlet
Chemical reactor outlet
Hel
ium
gas
tem
pera
ture
[oC
]
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Estimation of Tritium Permeation (1/2)
ObjectiveTo investigate the permeability on the material of the IHX tubes, Hastelloy XR.
Apparatus
Measurement Pipe(Hastelloy X)
Measurment System-Hydrogen
Cooling System
AutomaticControl System
MeasurmentSystem-Temperature-Pressure-Flow Rate
Heating System
Main Heater(6kW)
Gas Supply SystemH2/He,D2/Ar,etc.
Gas Purge SystemAr, He,etc.
Vacuum System
Flow Control
Pre-Heater(1kW)
Molecular Sieve
Flow Control
Molecular Sieve
Exhaust System
Hastelloy XR(Test Pipe)
Hydrogen and deuterium are used instead of tritium
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Estimation of Tritium Permeation (2/2)
The basic data on the permeability of hydrogen and deuterium has been obtained for the Hastelloy XR tube.
Experimental result
Temperature [oC] Partial pressure of H2 [Pa] E0 [kJ/mol] F0 [cm3(NTP)/(cm⋅s⋅Pa0.5)]
Hydrogen570 ∼ 820
1.06×102 ∼ 3.95×103 67.2 ± 1.2 (1.0 ± 0.2)×10-4
deuterium 670 ∼ 820 9.89×102 ∼ 4.04×103 76.6 ± 0.5 (2.5 ± 0.3)×10-4
Permeability : Kp = F0 exp(-E0 / RT)
Next research itemsTo investigate the permeability on the heat transfer tube material of the chemical reactor in IS process, SiC.To estimate the tritium concentration in the IS process and the produced hydrogen.
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Countermeasure against Explosion (1/2)
Principal countermeasures against explosion of combustible gas
Take a distance between the reactor and the hydrogen production system enough to mitigate the overpressure within an allowable range.
Protect blast with barriers such as wall, bank and so on.
Limit the leak amount of combustible gas.
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Countermeasure against Explosion (2/2)
Inner pipe
Outer pipe
Combustible gasFilled with nitrogen gas
Support
Manhole
Limit the leak amount of combustible gasDesign of coaxial pipe of combustible gas
Next research itemA conceptual design using a wall and/or a bank is under way from the viewpoint of mitigation of blast
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Development of High-Temperature Isolation Valve (1/4)Objective High-temperature
Isolation Valve (HTIV)Development of an isolation valve for the high-temperature condition around 900oC.
Technical issuesPrevention of the valve seat from thermal deformation
An angle valve with an inner thermal insulator was selected.
Development a new coating metal for the valve seat surface
A new coating metal was developed based on the Stellite alloy that is used for valves at around 500 oC.
Selection of a valve seat structure having a high sealing performance
A flat type valve seat was selected.
Confirmation of the seal performance and structural integrity
A component test was carried out using 1/2 scale model of HTIV.
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Development of High-Temperature Isolation Valve (2/4)
HTIV 1/2 scale modelNominal Size 22 B 16 BBore 200 mm 100 mmDesign Temp. (Casing) 350 oCDesign pressure 5.0 MPa 4.5 MPa
1/2 scale model of HTIV Actuator
Thermal insulator(Glass wool)Electric heater
Seat (HastelloyX)Coating metal (Stellite No.6 + 30wt%-Cr3C2)
RodBody (HastelloyX)
Casing (Carbon steel)
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He gas supply system
Ar gas supply system
Actuator
1/2 scale model of HTIV
Cooling water
To He gas detector
Exhaust
Electric heater
Electric heater
Thermal insulator
Development of High-Temperature Isolation Valve (3/4)
Apparatus
Experimental condition and procedure
(1) Helium gas was supplied to the 1/2 scale model of HTIV and increased up to 4.0MPa and heated up to 900oC.
(2) Valve seat was closed and helium gas at the upstream of the closed valve seat was exhausted. The pressure difference across the valve seat was set to 4.1MPa.
(3) The electric heater was shut off and the helium gas leak rate through the closed valve seat was measured from 900oC to 200oC by the helium gas detector.
Component test
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0 200 400 600 800 1000
10
1
10-1
10-2
10-3
10-4
Temperature of valve seat (oC)
4.4 cm3/s ： Target valueLe
ak ra
te o
f hel
ium
gas
(cm
3 /s)
Development of High-Temperature Isolation Valve (4/4)
Experimental resultComponent test
Next research itemThe improvement of the durability of the valve seat
The current technology can be applied to the HTTR hydrogen production system, however, the lapping of the valve seat is necessary after closing at a high temperature.
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Conclusion (1/2)The system integration technology has been developed for connection
of the hydrogen production system to HTGR. The following conclusions were obtained.
The control technology to keep reactor operation against thermaldisturbance caused by the hydrogen production system
JAEA proposed to use SG as the thermal absorber, which is installed downstream the chemical reactor in the secondary helium gas loop, to mitigate temperature fluctuation of secondary helium gas. By thesimulation test with the mock-up test facility, it was confirmed that SG could be used as the thermal absorber.
The permeability on Hastelloy XR which is the heat transfer tube material of IHX was obtained.
Tritium permeation from reactor to hydrogen
Next research item is to investigate the permeability on the heat transfer tube material of the chemical reactor in IS process, SiC, and to estimate the tritium concentration in the IS process and the produced hydrogen.
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Conclusion (2/2)
The new material for the coating of the valve seat surface was developed and the seal performance of the valve was confirmed to satisfy the design target with the 1/2 scale model of the high-temperature isolation valve. The improvement of the durability of the valve seat is the next target for the development.
The coaxial pipe of combustible gas was designed from the viewpoint of protection of the leakage aiming at arrangement of the hydrogen production system closed by the reactor. A conceptual design using a wall and/or a bank is under way from the viewpoint of the mitigation of the blast.
Countermeasure against explosion of combustible gas
Development of the high-temperature isolation valve to isolate reactor and hydrogen production systems in accidents
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The present study is the results of “Development of Nuclear Heat Utilization Technology“ in fiscal year from 1997 to 2001, 2003 and 2004 entrusted by Ministry of Education, Culture, Sports, Science and Technology (MEXT) to Japan Atomic Energy Research Institute (JAERI) succeeded by into Japan Atomic Energy Agency (JAEA).
The authors are indebted to Dr. S. Shiozawa and Dr. M. Ogawa fortheir useful advice and discussion in this research.
Acknowledgement
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Control TechnologySimulation test on loss of chemical reaction
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20
40
60
80
020406080
100120140
-1 -0.5 0 0.5 1
Experimental result
200
400
600
800
1000
0123456
-1 0 1 2 3 4 5 6Elapsed time [h]
SG outlet
SG inlet
Chemical reactor inlet
Chemical reactor outlet
Pre
ssur
ein
SG
[MP
a]H
e te
mpe
ratu
re [o
C]
Elapsed time [h]
Flow
rate
[g/s
]H
ydro
gen
prod
uctio
nra
te [m
3 /h]
Steam
Methane
Nitrogen