strategy of nuclear innovation after fukushima-daiichi

Koji OKAMOTO

Nuclear Professional School,

The University of Tokyo

okamoto@n.t.u-tokyo.ac.jp

Strategy of nuclear Innovation

after Fukushima-daiichi accident

from the view point of academia

Innovation for Cool Earth Forum

October 5-6, 2016, Tokyo, JAPAN

Pros / Cons for Nuclear Energy

Pros

Huge and stable energy source

CO2 free

Few fuel and few waste

Plutonium mine (fuel breeding)

Cons

Huge consequence with nuclear accident

Management for Radioactive material

Affected by social environment

Plutonium management (nonproliferation)

Superior energy source under no accidents

Important technical Lessons Learned

from Fukushima-Daiichi Accident

• External Event consideration

• Accident Management – Countermeasure for Total Station Blackout,

– Loss of Ultimate Heat Sink and

– Huge area damage

– Containment Vessel Protection

– Training and Education for Utility/Regulator

• Emergency preparedness

Improvements are strongly needed

Post-Fukushima Nuclear Plant

• Anyway SAFE

• Release of radioactive material should be

practically eliminated.

• Secure the reactor by multiple layer of

protection and mitigation strategy.

• High-level radioactive waste should be

reduced and safely disposed.

Demands for Nuclear Power

• 3E+S (Energy security, Economics, Environment + Safety)

• CO2 free energy source

• Japan has few natural resources (95% of Energy resources have to be imported)

Safe Nuclear Reactor;

Severe Accident is practically eliminated

Co2 free energy source for 2030~2050

Steal

making

13 %

Civil

13%

Automobile

17 %

Others

23 %

Power generation

26 %

Petrochemistry

8 %

For the Cool Earth,

CO2 free Power Generation is not enough

11.9 hundred million tone (2010)

CO2 Emission

Industrial Heat and Transportation

should be CO2 free

Fast Breeder Reactor

• Safety Nuclear Power System

– Natural circulation can cool reactor without electricity

– MONJU R&D, incl. Safety researches

– Future Commercial FR plant design

• Reduction of High-level radioactive waste

– Transmutation of Minor Actinide using MONJU

• Fuel Cycle Technologies

– Production of Plutonium

• High-temperature (500℃) energy source

– Desalination, high-temperature steam

Schematic of Monju

Electricity Output : 280MWe (714MWt), Sodium-cooled, MOX-fueled

Primary sodium cooling loop Water/steam system

Secondary sodium

Primary sodium

Intermediate Heat Exchanger (IHX)

Primary Circulating

pump

Core

Air cooler

（AC)

Evaporator (EV)

Turbine Generator

Feed water pump

Sea water pump

Condenser

Secondary sodium cooling loop

Secondary Circulating

pump

Super heater (SH)

SH

EV ＩＨＸ

ACS

SH

EV ＩＨＸ

ACS

SH

EV ＩＨＸ

ACS

R/V ＴＢ

loop C

loop B

loop A Temperature, flowrate etc.

Primary sodium reactor vessel inlet/outlet: 529/397˚C, 5100 t/h/loop

Secondary sodium IHX inlet/outlet: 325/505˚C, 3700 t/h/loop

Steam at the turbine inlet: 483˚C, 12.5MPa, 1137 t/h

8

R&D on “Monju”

Aggregate of the fast breeder reactor technology Core and fuel technology

Confirmation of higher isotopes of Pu core

characteristics based on the actual reactor data.

Equipment and system design technology

Plant system design technology

Design technology of large sodium equipment

Sodium handling technology

Development of in-service-inspection technology for

the reactor vessel, etc.

Plant operation and maintenance technology

Establishment of a maintenance program in light of the

characteristics of the FBR power plant, etc.

Irradiation test (X-ray CT image)

Core design approach and core

management technology

Examples of specific reflections

Reactor kinetic characterization

and shielding evaluation methods

Aging characteristics and Integrity

of sodium equipment

R&D for reducing the waste volume and radiotoxicity Evaluate of the MA transmutation and the irradiation behavior

by full-scale irradiation tests with MA-bearing MOX fuel, etc.

R&D of enhanced safety Demonstrate the decay heat removal in the actual plant as a

feature of the sodium-cooled FR with natural circulation

◉Aggregate the outcome of the FBR technology development including the

technical feasibility of the FBR plant, and Reflect it in the next reactor design

by utilizing "Monju“ of our own design, manufacturing, and construction.

Na management techniques of

loop-type FR power plant

High-Temperature Gas-cooled Reactor

• Super Safety

– No Severe Accident (Inherent Safety with physics)

• Large negative reactivity feedback

• Cooling without electricity

• Confine FP inside the fuel particle

• High temperature heat

– Desalination, Electricity, Process heat, ….

• Stability of high-level waste

– Spent TRISO fuel contains FP stably over 100,000 years

Stop

Cool

Confine

11

GTHTR300: Gas Turbine High Temperature Reactor 300

Reactor

Turbine Generator

Core

Precooler

Recuperator

Compressor

Main Specifications

Reactor thermal power : 600MW

Reactor outlet temperature: 850ºC

Reactor inlet temperature : 587 ºC

Coolant pressure : 7 MPa

Electric power : 275MW

Generating efficiency : 45.8%

JAEA Design

Multi-purpose HTGR Electricity, Hydrogen, Heat, Water

GTHTR300

One unit of HTGR supply capacity

60,000Nm3/day Hydrogen

Heat supply to industries

40,000t/day desalination

300MWe Electricity

Contribution in non-electricity area

Potentiality of HTGR for GHG reduction in Japan

13

Steal

making

13 %

Civil

3%

Automobile

17 %

Others

23 %

Power generation

26 %

CO 2 emission

11.9 hundred million tone (2010 )

Civil

13 %

Others

23 %

Power generation

26 %

30 ％ decrease Decrease with HTGR

Petrochemistry 3 % Steal making 4% Automobile 1 %

Hi. temp.

heat

H 2

HTGR (600 MW)

Steal making with H 2 reduction Petrochemical plant Fuel - cell powered automobile

H 2 (Fuel)

16 ％ decrease

HTGR : 30 units

Hi. temp. heat, H 2 ( reductant )

9% decrease

HTGR : 20 units

Hi. temp. heat, Steam

5% decrease

HTGR : 15 units

Steam

1 unit = 4 HTGRs

Petrochemistry 8 %

Time

Short time scale（sec~min）

Utilize large core heat capacitance

Nuclear

Solar ・Wind

Long time scale（hr~day）

Control power/thermal ratio

according to power demand. GTHTR300 renewable hybrid system

Constant

＋ Constant power

H2

GTHTR300 nuclear-renewable hybrid system

H2 plant

Precooler

Recuperator

Power generation

rate control

Heat supply

rate control

Control flow

Coolant flow

IHX

Renewable energy power plant

Reactor

Core

Allowable core thermal capacitance: 850 MJ/oC

Power

synthesisConstant

power

Electric grid

Coolant inventory Bypass flow rate

Power

output

Power

output

Generator

Gas turbine

Pow

er

genera

tion r

ate

14

Summary

• Safety Nuclear System is available

• Fast Breeder Reactor

– Safety with natural circulation

– MONJU Restart

– Reduce CO2 with high temperature

• High Temperature Gas-cooled Reactor

– Super-Safety during operation and disposal

– Reduce CO2 with H2 production and

Industrial heat

– Combination with Renewable energy