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Role of Nuclear Energy and University Research
Yoshiaki OkaProfessor, Waseda UniversityShinjuku‐ku, Tokyo, Japan
Emeritus professor, University of Tokyo
Special panel session celebrating the 75th anniversary of the discovery of fission , November 13, 2013, American Nuclear Society, Winter Meeting. Washington DC, USA
1
Outline
• Energy sources, Global warming, Nuclear energy
• Role of University Research• Super LWR and Super FR studies, • High breeding by light water cooling, • R&D of Thermal hydraulics and materials• New textbooks of nuclear engineering
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Energy sources
3
Fossil fuels are major primary energy source since industrial revolution for 250 years
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html 4
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html 5
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html 6
Many countries depend on imported energy sources
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html
US energy (basic) policy : Less than 25% of import dependence for national security
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Global warming
8
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html 9
Temperature rise in 2000‐09 Compared to average temperatures recorded between 1951 and 1980
The most extreme warming, shown in red, was in the Arctic
Source: Wikipedia；Global warming10
Source; http://www.fepc.or.jp/library/publication/pamphlet/nuclear/zumenshu/index.html 11
Nuclear energy
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US electricity production costNuclear is the cheapest after depreciation of the construction cost
Source: http://world‐nuclear.org/info/inf02.html13
Natural gas prices (2005‐2012)not stable
Source：JOGMEC, http://www.jogmec.go.jp/library/contents8_05.html
USA
Japan
UK
Germany
Japan(imported LNG)USA(NYMEX)UK (ICE)Germany (Russian boarder)
Combined cycle gas turbine power plantsInnovation of power plant technology
Source: Wikipedia
What necessary for future nuclear power?
• Improve NPP operation& maintenance; Safe operation, decrease in outages etc.
• Improvement of LWR technologies• New construction: keeping work force and skills• Decrease in capital cost of LWR; Compete with CCGT in construction
• Innovation of nuclear power plant technologiesLarge plantsSmall plants? Seek innovation?
• Raising human resources for the future
Types of researches• Industries: Work for commercial products
Unknowns should not remain and be avoided.
• Research institutes : Work for projects
• Universities: Explore unknown area and raise human resources:
• Information exchange among the parties is important
SCWR, Supercritical‐pressure water cooled reactors
• Not constructed before, nor similar plants• Reactor concept itself needs to be explored through design study (by numerical simulation)
• Good subject for students to learn methods and fundamentals of LWR design and safety
• Difference is small, but need to develop methods/concepts and ideas for SCWR
What is supercritical water?• No boiling phenomenon • High specific enthalpy
SolidLiquid
Gas
Critical point（22.1MPa, 374℃）
Supercritical
Temperature
Pres
sure
Phase diagram of water
Temperature [℃]Spec
ific
heat
[kJ/
kg/K
]
0
10
20
30
40
50
100 200 300 400 500 600
24 MPa7 MPa
0
200
400
600
800
1000
100 200 300 400 500 600
24 MPa
7 MPa
Temperature[℃]
Den
sity
[kg/
m3 ]
19
20
Circular Boiler
Water tube boiler
Once-through boiler
LWR
Super LWR, Super FR (SCWR)
Evolution of boilers
Water level
Water level
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Control rods
Supercritical water
Turbine Generator
Condenser
PumpHeat sink
Reactor
Core280℃
500℃
Super LWR and Super FR• Super LWR: reactor developed at Univ. of Tokyo and Waseda
university• Super FR: Fast reactor version of Super LWR (MOX fuel) • Once‐through direct coolant cycle
• Pressure: 25 MPa• Inlet: 280℃• Outlet (average): 500℃• Flow rate: 1/8 of BWR
Super LWR:a thermal reactor concept
3‐D N‐T Coupled Core Calculation• T‐H calculation based on single channel model
• Neutronic calculation; SRAC
Core consists of homogenized fuel elements
Fuel assembly
HomogenizedFuel
element
1/4 core Single channel T-H analyses
3-D core calculation
qc(i) qw(i)
pelletCladding
Coolant
Moderator
Water rodwall
Single channel T-H model
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Coolant flow scheme (two pass core)
Mix
Inlet:
Outlet:
OuterFA
Inner FA
CR guide tube
Coolant ModeratorInner FA Upward DownwardOuter FA Downward Downward
Flow directions
To keep high average coolant outlet temperature
Kamei, et al., ICAPP’05, Paper 552724
Two pass core (previous) One pass core (improved)
Improvement flow scheme of Super LWRone pass core
Fuel loading pattern of the core
Inner and peripheral core assembliesof high temperature core
Characteristics of high and low temperature cores of Super LWR
Cores High T. core Low T. core
Thermal power/electric power[MW] 3492/1530 2804/1200
Thermal efficiency[%] 43.8 43.1Operating pressure[MPa] 25 ←
Temperature inlet/outlet[⁰C] 280/500 280 / 465
Max. Cladding Surface Temp.[⁰C] 656 650Number of fuel assembly 129 121Average fuel enrichment 7.31 7.30Fuel/cladding UO2/SS ←Average power density[MW/m3] 97.6 93.4Core effective height/diameter 4.20/3.31 3.70/3.23Discharge burnup[GWd/t] 45.3 43.3Max. Linear Heat Gene. Rate[kW/m] 37.4 38.5
To be presented tomorrow at 1pm
Safety principle of Super LWR• Keeping coolant inventory is not suitable due to no water level and
large density change.• Coolant inventory is not important due to no circulation. • No natural circulation
Safety principle is keeping core coolant flow rate.
Coolant supply (main coolant flow rate)
Coolant outlet (pressure)
BWR PWR Super LWR
Requirement RPV inventory PCS inventory Core flow rate
MonitoringRPV water
levelPressurizer water level
Main coolant flow rate, Pressure
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LPCI line
SLCSControl rods
RPV
Turbine bypass valves
Turbine control valves
Condenser
LP FW heaters
HP FW heaters
Reactor coolant pump(Main feedwater pump)
LPCI
AFS
Turbine
AFS
AFS
Condensate water storage tank
LPCI
LPCI Suppression chamber
SRV/ADSContainment
Deaerator
Cond
ensate
pumps
Booster pumps
Plant and safety system
MSIV
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31
Analysis code for supercritical‐pressure
Mass conservation
Energy conservation
Momentum conservation
-downcomer / water rod
-average / hot channels
Radial heat transfer
-Oka-Koshizuka correlaiton
Point kinetics 31
Summary of safety analysis results
0
100
200
300
400
500
600
Transients Accidents ATWS without alternative action ATWS with alternative action (ADS)
1 2 3 4 9 1 2 3 5 6 1 2 3 4 6 7 9
Criterion for transient
Criterion for accident and ATWS
Event number
Incre
ase o
f te
mpera
ture
fro
m initia
l va
lue [
℃]
100
120
140
160
180
200
8 3 7 6 9
Criterion for powerrising rate of 0.1-1%
Criterion for power rising rate of 1-10%
Criterion for powerrising rate of ovre 10%
Transient number
Peak
pow
er
[%]
25
26
27
28
29
30
31
2 3 4 8 9
Transients Accidents ATWS without alternative action ATWS with alternative action (ADS)
3 4 2 3 4 7 8 9
Criterion for transient
Criterion for accident and ATWS
Event number
Peak
pre
ssure
[M
Pa]
Transients Accidents1. Partial loss of reactor coolant flow2. Loss of offsite power3. Loss of turbine load4. Isolation of main steam line5. Pressure control system failure6. Loss of feedwater heating 7. Inadvertent startup of AFS8. Reactor coolant flow control system failure9. Uncontrolled CR withdrawal at normal operation10. Uncontrolled CR withdrawal at startup
1. Total loss of reactor coolant flow 2. Reactor coolant pump seizure3. CR ejection at full power 4. CR ejection at hot standby5. Large LOCA 6. Small LOCA
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Super FRa fast reactor concept
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Advantages of Super Fast Reactor Same plant system as Super LWRHigh power density of Super FR is an advantage in capital cost over Super LWR and LWR Capital cost; Super FR< Super LWR< LWR
Low reactor coolant flow rate (due to high enthalpy rise) High head pumps Suitable for tight fuel lattice core of Super FR No pumping power increase and instability problems of high conversion LWR
Coolant flow schemes of Super FR
Fuel assemblies and core of Super FR
seed fuel assembly
blanket assembly Loading pattern of one path core
Super FR (one pass core) characteristics
Power MWt/MWe 2337/1006Coolant pressure (MPa) 25.0Inlet/outlet temperature (oC) 280/501Active/overall power density (kW/L) 206/149Number of seed assembly 78Number of blanket assembly 37Active core height (m) 2.4Eq. active core diameter (m) 2.47Pu enrichment in seed assembly (wt%) 32(bottom)/25(top)Pu enrichment in bottom blanket (wt%) 10(bottom)Cycle length (EFPD)/fuel batch 200/3Average/max discharge burn-up (GWd/t) 53.8/72.7
High breeding by light water cooling
Tightly packed-rods fuel assembly
breeding core
Characteristics of high breeding core and comparison with RMWR (reduced moderation BWR)
Scope of studies and Computer codes1.Fuel and core
Single channel thermal hydraulics (SPROD), 3D coupled coreneutronic/thermal-hydraulic (SRAC-SPROD), Coupled sub-channel analysis, Statistical thermal design method, Fuel rodbehavior (FEMAXI-6), Data base of heat transfer coefficientsof supercritical water
2. Plant system; Plant heat balance and thermal efficiency3. Plant control4. Safety; Transient and accident analysis at supercritical-and
subcritical pressure, ATWS analysis, LOCA analysis (SCRELA)5. Start-up (sliding-pressure and constant-pressure)6. Stability (TH and core stabilities at supercritical and
subcritical-pressure)7. Probabilistic safety assessment
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43Super Fast Reactor R&D1st Phase (2005‐ 2010), 2nd phase (2010‐2014)
1st phase: University of Tokyo, JAEA, Kyushu Univ. and TEPCO2nd phase: Waseda University, Univ. of Tokyo, JAEA, Kyushu Univ. Tohoku univ. TEPCO systemsentrusted by MEXT
Development of the Super FR concept
Thermal‐hydraulic experiments Materials experiments
Thermal hydraulic experiment with surrogate fluidSupercritical thermal hydraulic loop of Kyushu University
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Thermal hydraulics R&D
1. Single tube/rod bundle experiments2. Critical heat flux experiment at subctritical‐
pressure3. Critical flow measurement4. Condensation experiment5. Cross flow measurement
Surrogate Fluid (Freon) at Kyushu University
Supercritical water at JAEA1. Single rod/rod bundle experiment2. Single tube experiment at high temperature 45
Materials R&D• Developed 15Cr‐20Ni SS cladding material based on cladding material for LMFBR
• Developed thermal insulating material, Yttria‐stabilized zirconia (YSZ)
• Measurement of Corrosion and elusion characteristics of cladding materials
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Mass transfer experimentsElusion and deposition characteristics from 20C to 550C and to 20C
Diagram of mass transfer experiment loop
Auto crave
Control system
Super LWR design study started in 1989.
Results of the design study (until 2009) are summarized.
Also a textbook of reactor design and anlysis: Core & fuel design, plant control, start‐up, plant heat balance, stability, safety design and analysis of Super LWR and Super FR as well as the comutational methods
Publidhed in July 2010 from Springer
2nd book “ supercritical pressure light water cooled reactors” is under preparation. 48
Source:http://www.springer.com/engineering/energy+technology/book/978‐1‐4419‐6034‐4
Contents: PSA in design and maintenance of ABWR, Passive ECCS of APWR, Severe accident mitigation features of APR1400, EPR core catcher, Severe accident research in China, Full MOX core design of ABWR, CFD applications, Digital I&C system, 3D-CAD application to construction, Progress in seisimic design
Available from Springer, 295 pages
Based on the lectures of International summer school of NPP and young generation work shop“; Bridgeing fundamental research and practical applications” in 2009 in Tokai-mura Japan
http://www.springer.com/engineering/energy+technology/book/978‐1‐4419‐7100‐5
最新の原子力教科書日本の優れた原子力発電技術と３０年間の実用の進展を反映
英語版も作成中（Springerより出版）
第2号 第3号第1号 第4号
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英語版出版
第6号
英語原稿作成
第5号
第9号 第10号
英語原稿作成
第11号
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英語原稿作成
第7号 第8号
英語原稿作成
第12号
英語原稿作成
Modern textbooks of nuclear engineeringincluding advancement in 30years
English versions are under preparation at U.Tokyo
Source:http://www.springer.com/engineering/energy+technology/book/978‐4‐431‐54194‐3
Thank you
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