IntroductionThe Evolution of Nuclear Power

GoalsProduction of electricity while meeting the goal of clean air, and effective use of fuel resources

Compared with other energy sources, it has obvious price advantages during its lifetime.

Excellent safety and reliabilityVery Low Core Damage Probability and Degree

01 Sustainability

03 Safety

05Public Acceptance

02Economics

04Proliferation resistance

It is designed to make it difficult to extract nuclear materials from weapons or to reduce the available level. Managing to ensure that weapons and nuclear materials are not easily stolen

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Very High Temperature gas cooled Reactor (VHTR)

Lead cooled Fast Reactor (LFR)

Super-Critical Water cooled Reactor (SCWR)

Gas cooled Fast Reactor （GFR）

Molten Salt Reactor（MSR）

GenerationⅣ

Sodium-cooled Fast Eactor（SFR）

Types

Very High Temperature Reactor(VHTR)• Graphite moderated helium-cooled reactor.• The core type is a prismatic block core like Japan's HTTR, or a pebble bed core like

China's HTR-10.

• VHTR is at a high temperature near 600-1000 degrees at the exit of the generated heat, and it is possible to achieve gas turbine combined power generation with high thermal efficiency.

Advantage• There is no risk of meltdown.• The temperature behavior at the time of abnormality is slow.• It can make hydrogen.

Disadvantage

• It can not be smaller.• Need some reactor for generating enough output.

• The ability of fast neutron reactors to fission all trans-uranic elements, andto convert the non-fissile 238 U to fissile 239 Pu, provides a far higherdegree of sustainability than thermal reactors.

• The very high-energy densities necessary in a fast reactor core require avery efficient means of heat transfer or the use of highly refractory coreand coolant materials.

Fast reactor

239 Pu,fast

neutron

238 U+ 239 U

2×β decay

239 Pu

...239 U

fast neutron

The lead-cooled fast reactor is a nuclear reactor design that features a fast neutron spectrum and molten lead or lead-bismuth eutectic coolant.

Why use lead:1.Excellent thermo-fluid-dynamic properties 2.It can serve as a neutron reflector.3.It does not react with air and water.4.High boiling point

Lead-cooled fast reactor（LFR）

Benefits:

•High degree of passive safety•Proliferation resistance of long-life cartridge core

•Natural circulation cooling

Disadvantages:

• Corrosion damage•Difficulty in construction•High expense of coolant

Implementation：1.European Lead-cooled System（ELSY）2.Small Secure Transportable Autonomous Reactor(SSTAR)3.SVBR(in Russia)

SSTAR

Molten Salt Reactor (MSR)

What is MSR?• Reactors using molten salt for FUEL or COOLANT.

• Thermal reactors and Fast reactor are designed.

• Fluoride and Chloride are mainly used.

(exp. LiF-BeF2-UF-ThF4)

• U, Pu , Th can use for fuel.

• First reactor is made for aircraft engine.

Advantage Low pressured coolant system Big negative feedback Few volatility FP emit Easy to discharge fuel from core Big actinide dissolve

Disadvantage Strong corrosion by salt Huge area is containing fuel Difficult to maintaining Few research data and technique

Supercritical Water Reactor (SCWR)?

• SCWR concept is based on two proven technologiesThe supercritical fossil fired boilers deployed

around the world.Currently deployed light water reactors (LWRs).

• Two types of SCWR concepts that differ in the approach to the reactor designBased on the current light water reactor design

(PWR, BWR).Pressure tube design, which is a logical evolution

of CANDU types reactors.Both designs operate with a direct, one through

cycle.

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Benefits of Supercritical Water Reactor (SCWR)

• High thermal efficiency

High temperature (above 374oC) and high pressure (above 25MPa) lead to high thermal efficiencyThermal efficiency of SCWRs is expected to

be 1.2 to 1.4 times higher than that of current water cooled reactor

2Fig. 1. supercritical water pressure, T-S diagram.

Buongiorno, Jacopo, and P. MacDonald. "Supercritical water reactor (SCWR)." Progress Report for the FY-03 Generation-IV R&D Activities for the Development of the SCWR in the US, INEEL/Ext-03-03-01210, INEEL, USA, September (2003).

Benefits of Supercritical Water Reactor (SCWR)• Simplification of plant system and low capacity

componentsWithout phase change in the coreEliminating recirculation system and steam-

water separation system in BWREliminating steam generators and a

pressurizer in PWR

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Fig. 2. schematic of SCWR. [1]

Buongiorno, Jacopo, and P. MacDonald. "Supercritical water reactor (SCWR)." Progress Report for the FY-03 Generation-IV R&D Activities for the Development of the SCWR in the US, INEEL/Ext-03-03-01210, INEEL, USA, September (2003).

Requirements of materials for SCWRs• High-strength and corrosion resistance at

up to 500 ~ 600 oC.• Low susceptibility to SCC.• Reasonably-low neutron absorption.• Dimensional stability at up to 5dpa.

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• Austenitic steels (good for corrosion).• Nickel base alloys (good for corrosion).• Ferritic-martensitic steels (good for SCC).

Candidate materials

Sodium cooled Fast Reactor (SFR)

What is SFR?• SFR uses liquid sodium as the coolant.

Sodium does not slow down neutron.U238 is transmuted into Pu239 by fast neutron.

• Canada, China, EU, France, Japan, Korea, Russia, India are developing SFR.

Advantage Low pressured coolant system High power density Convert U238 to Pu239

⇒ Breeding Fuel Reduce actinide wastes

Disadvantage Sodium has chemical reactivity Unable to observe inside the reactor If a void occurs,

it becomes positive feedback

Gas-Cooled Fast Reactor (GFR)GFR Description:The GFR system features a fast-spection helium-cooled reactorand closed fuel cycle.The GFR reference assumes an integrated ,on-sited spent fuel treatment and refabrication plant.

Characteristics:•Helium coolant•850°C outlet temperature•Direct gas-turbine cycle

A summary of design parameters for the GFR

Reactor Parameters Reference Value

Reactor power 600 MWth

Net plant efficiency (direct cycle helium) 48%

Coolant inlet/outlet temperature and pressure 490°C/850°C at 90 bar

Average power density 100 MWth/m3

Reference fuel compound UPuC/SiC (70/30%) with about 20% Pu content

Volume fraction, Fuel/Gas/SiC 50/40/10%

Conversion ratio Self-sufficient

Burnup, Damage 5% FIMA; 60 dpa

GFR's Advantages/Disadvantages

The most important Benefits:•Waste minimization and efficient use of uranium resources

This is reflected in two points.1.A high tempreture enabling an elevated efficiency helium brayton cycle for electricity generation and generative applications.

2.The management for an efficient exploitation of nuclear fuel (with a converter operating mode).

Disadvantages：Because of higher core power density，this technology requires complex, innovative and expensive security systems to ensure continued pressurisation of the RPV and core cooling in accidental situations.

The Performance issues:•Development of materials with superior resistance to fast-neutron fluence under very-high-temperature conditions.

•Development of a high-performance helium turbine for efficient generation of electricity.

Summary

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Generation-IV goal

VHTR LFR MSR SCWR SFR GFR

Sustainability Low High Middle Middle High High

Economics High High High High High High

Safety and Reliability

High Low Middle Middle Middle Middle

Current technical feasibility

High Middle Low Middle High Low

Main areas of R&D

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• Materials technology

resistance to irradiation damage

high-temperature creep

corrosion resistance

• Nuclear fuel reprocessing

Advanced aqueous process

pyro-process

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