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Physics 1003

https://canvas.ust.hk/courses/1900 or 1901

Lecture 17

Nuclear energy I

Outline

• Nuclear energy; Nuclear reactors;

• Sustainability of nuclear energy;

• Road map of China’s nuclear power .

Instructor-in-charge: K. S. Wong

Email: phkswong@ust.hk

TA-in-charge: KUANG Guowen (gkuang@connect.ust.hk)

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Electricity from Nuclear Reactors

Source: Xu Kuangdi , 2010

Phys1003 – L14 & L15

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http://www.worldnuclearreport.org/World-Nuclear-Report-2013.html

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Nuclear reactors under construction, ordered or planned and proposed

Country Under construction Ordered or planned Proposed

# MWe # MWe # MWe

China 28 31,635 58 62,635 118 122,000

India 6 4,300 18 15,100 39 45,000

Russia 10 9,160 31 32,780 18 16,000

World 62 63,724 155 173,535 341 388,455

http://www.world-nuclear.org/info/reactors.html Feb. 2014

• It is expected that the number of nuclear reactors will be more

than doubled in the future. The fact that Germany intends to phase

out nuclear power will have little effect on this trend.

• The new nuclear reactors are Generation III reactors which are far

more safe. Generation IV reactors which are being developed for

deployment after 2030 are even safer.

MWe stands for Megawatt of Electric Energy

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Nuclear power plant

Pressurized water reactor (PWR) • Nuclear Reactor device built to sustain a controlled nuclear fission chain

reaction.

• A Pressurized Water Reactor (PWR) keeps water under pressure so that it heats

up ut does ’t oil. The ater i the rea tor heats the ater i the stea generator side, but it is on a different loop so they do not mix.

www.pbase.com/pbrakke/image/44279993

http://en.wikipedia.org/wiki/Image:Crocus-p1020491.jpg

Main Components :

- reactor vessel

- tubes of uranium

- control rods

- containment structure

• Control rods control

radioactivity by absorbing

neutrons.

• Containment structure

contains the reaction in at

least 3 feet of concrete!

http://www.youtube.com/watch?v=MSFgmLW1Crw 6 min

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https://www.gen-4.org/gif/jcms/c_40481/technology-roadmap

An overview of the generations of nuclear energy systems

LWR – Light Water Reactor; PWR – Pressurized Water Reactor;

BWR – Boiling Water Reactor; CANDU – CANada Deuterium Uranium reactor; AGR -

Advanced Gas-cooled Reactor;

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Nuclear fission • Collision of a relatively slow-moving

neutron with uranium-235 can split it

into two smaller nuclei. Neutrons are

also released in the process, along

with a great deal of energy.

• During nuclear fission, the nucleus

usually divides asymmetrically rather

than into two equal parts.

• Moreover, every fission event of a

given nuclide does not give the same

products; more than 50 different

fission modes have been identified

for uranium-235, for example.

• A distribution of many pairs of fission

products with different yields can be

obtained.

Mass Distribution of Nuclear

Fission Products

http://www.youtube.com/watch?annotation_id=annotation_696116&f

eature=iv&src_vid=kHXMiYsFSrU&v=Ezbyg2iNdQs 1 min

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Nuclear energy Reading : Chapter 24. Nuclear? P161-176,

Sustainable Energy -- Without the Hot Air (David MacKay)

http://www.withouthotair.com/download.html

• The nuclear energy available per atom is roughly one million

times bigger than the chemical energy per atom of typical fuel.

• The amount of fuel and waste that must be dealt with at a

nuclear reactor can be up to one million times smaller than the

amounts of fuel and waste at an equivalent fossil fuel power

station.

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Nuclear fuel - 235U and depleted uranium

• The percentage of 238U and 235U isotopes in natural

uranium oxide is 99.284%, and 0.711%. 235U is the

only naturally existing isotope (in any appreciable

amount) that is fissile with thermal neutrons.

• The natural uranium oxide has to be enriched to

contain 3-4% of 235U (LEU) for use in nuclear reactors,

or to 90% 235U (HEU) for use in nuclear weapons.

• Uranium ore is first processed into yellowcake powder

which is in turn purified for use in fuel rods in nuclear

reactors.

• The 238U remaining after enrichment is known as

depleted uranium, and is considerably less radio-

active than natural uranium, but still extremely

hazardous.

~1cm in length and diameter, and

weight ~10g

• The fossil fuel consumption per day per person in the UK is 4 kg of coal, 4 kg

of oil and 8 kg of natural gas.

• The amount of natural uranium required to provide the same amount of

energy as 16 kg of fossil fuels in a standard nuclear fission reactor is 2 grams.

• To deliver 2 grams of uranium per day, 200 grams of ore have to be mined per

day.

235 is the mass number and 92 is the atomic number.

235 12

• Sustainable means having resource to last not less than 1000 years.

• Current world consumption of uranium is about 77,000 tons per year. It

will increase by approximately 30% - 60% to between 102,000 - 127,000

tons per year by 2025. Is nuclear power sustainable?

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“ustai a le power fro u lear fission

• World reserve of uranium in the ground (ore reserve) is 4.7 millions tons.

• World reserve of uranium in phosphate deposits is 22 million tons. Some

20,000 tons of uranium has already been obtained from these rock

phosphate deposits, but the process became uneconomic in the 1990s.

• There are 4.5 billion tons of uranium in the seawater in the world. However,

uranium extraction from seawater has not been demonstrated on an

industrial scale.

• The total uranium reserve is therefore about 27 million tons.

14 http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/

Supply of Uranium

15 http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/

RAR – Reasonably Assured

Resources

IR – Inferred Resources

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There are two ways to use uranium in a reactor:

(a) widely-used once-through reactor gets energy from 235U;

(b) fast breeder reactor gets roughly 60 times more energy from 238U.

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Once-through reactor:

The fast neutrons produced in fission do not cause fission as efficiently as slower-

moving ones so they are slowed down in once-through reactors by light water, or

heavy water, or graphite, which cools the neutrons to optimum energies for causing

fission.

Fast breeder reactor:

Natural uranium consists primarily of 238U, which does not fission readily. In a fast

breeder reactor, the fast neutrons are captured by 238U, which then becomes

plutonium (239Pu). This plutonium isotope can be reprocessed and used as more

reactor fuel.

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Once-through reactors, using uranium from the ground

• A once-through 1 GW nuclear power station uses 162 tons of

uranium per year. The energy from 27 million tons of U

= 27×106 tons of uranium/162 tons of uranium per GW-year

= (27/162)×106 GW-yr

• Sharing this among 7 billion people for 1000 years means the energy

per person is given by

(27/162)×106 GW-yr / 7×109 p×1000 yr = 23.8 W/p

= (23.8 W/p) × 24 h/d

= 0.57 kWh/d-p.

• This is much less than the 18 kWh/d-p of electricity generated by

burning 45 kWh/d-p of fossil fuels.

• We need roughly 40 times more uranium for the once-through use to

be sustainable.

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Fast breeder reactors, using uranium from the ground

• Uranium can be used 60 times more efficiently in fast breeder reactors,

which burn up both 235U and 238U.

• The depleted uranium from the once-through reactors can be used in

fast breeder reactors.

• The 27 million tons of uranium used in 60-times-more-efficient fast

breeder reactors would provide about 40 kWh/d-p.

• Thus fast breeder reactors are sustainable.

• Electricity has been produced in fast breeder reactors in France, India,

Japan and Russia. But the fast breeder programs in the US and UK were

terminated.

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Once-through, using uranium from the oceans

• Uranium in the oceans, if completely extracted and used in once-

through reactors, corresponds to a total energy of

4.5 billion tons/162 tons per GW-yr = 28 million GW-yr

• The ocean circulation is slow, and deep Pacific waters circulate to the

surface every 1600 years. Assuming 10% of the uranium is extracted

over a period of 1600 year, the extraction rate

= 450 million tons/1600 years = 280,000 tons/year.

• The power is delivered in once-through reactors at a rate of

2.8 million GW-yr / 1600 yr = 1750 GW

• 1750 GW is almost 5 times the present power from all the nuclear

reactors in the world, which is 370 GW.

• 1750 GW shared between 7 billion people is

(1750 GW/ 7 billion people) ×24 h/d = 6 kWh/d-p

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Fast breeder reactors, using uranium from the oceans

• If fast breeder reactors are 60 times more efficient, the same

extraction of uranium could deliver 360 kWh/d-p.

• This is definitely sustainable.

• The sustainability depends on the extraction of uranium in

oceans and building fast breeder reactors. The former is not yet

developed and the latter is controversial.

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“ustai a le po er fro ura iu

Nuclear reactor Mine U Ocean U

Once-through 0.57 kWh/d-p 6 kWh/d-p

Fast breeder 40 kWh/d-p 360 kWh/d-p

Source: Fig. 24.6, Sustainable Energy, MacKay

• Current world nuclear power production: 1.2 kWh/d-p

• Current British nuclear power production: 4 kWh/d-p

23 http://www.world-nuclear.org/info/Current-and-Future-Generation/Fast-Neutron-Reactors/

The FNR was originally conceived to burn uranium

more efficiently and thus extend the world's uranium

resources – it could do this by a factor of about 60.

However significant technical and materials problems

were encountered, and also geological exploration

showed by the 1970s that uranium scarcity would not

be a concern for some time. Due to both factors, by

the 1980s it was clear that FNRs would not be

commercially competitive with existing light water

reactors for some time.

Today there has been progress on the technical front,

but the economics of FNRs still depends on the value

of the plutonium fuel which is bred and used, relative

to the cost of fresh uranium.

Also there is international concern over the disposal of

ex-military plutonium, and there are proposals to use

fast reactors (as "burners") for this purpose.

In both respects the technology is important to long-

term considerations of world energy sustainability.

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Costs of extracting uranium from oceans

• Japanese researchers have developed a technique for extracting uranium

from seawater at a cost of US$100-300/kg of uranium.

• The current cost of uranium from mines is US$20/kg.

• Uranium contains so much more energy per ton than fossil fuels that a 5-fold

or 15-fold increase in the cost would have little effect on the cost of nuclear

power.

• The price of nuclear power is dominated by the cost of power-plant

construction and decommissioning. A price of US$300/kg increases the cost of

nuclear energy by about 0.3 pence/kWh.

• I the Japa ese e peri e t, ore tha kg of ello ake i da s as harvested using 350 kg of uranium-absorbing materials with an effective area

of 48 m2 which corresponds to 1.6 kg of uranium a year.

• To power a once-through 1 GW nuclear power plant (160 tons a year), the

rate of production has to increase 100,000 time.

Self-Reading Materials

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Costs of extracting uranium from oceans

• Scale up the Japanese technique, a power of 1 GW would need absorbing

materials with a collecting area of 4.8 km2 weighing 350,000 tons, heavier

than the steel in a reactor.

• If each 1 GW reactor is shared by 1 million people, the power delivered is

1000 W, or about 22 kWh/d-p; and the uranium used is 0.16 kg per person

per year.

• So each person would need one tenth of Japanese experimental facility, a

weight of 35 kg per person and an area of 5 m2 per person.

• The proposal that such uranium-extraction facilities should be created is, as

e shall see later, si ilar i s ale to proposals su h as e er perso should have 10 m2 of solar pa els a d e er perso should ha e a o e-ton car and

a dedi ated parki g pla e for it .

• For fast breeder reactors, 60 times less of everything is needed, but it is still

not realistic!

Self-Reading Materials

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Land use

• The Sizewell nuclear power station in UK

with generation capacity of 1 GW

occupies less than 1 km2. The power per

unit area of nuclear power station is

larger than 1000 W/m2.

• The power needed to provide 22 kWh/d-p in the

UK is

(22 kWh/24h-p)×60×106 p = 55 GW.

• 55 Sizewell equivalent nuclear power stations,

each occupying 1 km2 have to be built, about

0.02% of the area of the country.

• If the nuclear power stations were placed in pairs

around the coast, there will be two every 100

km.

Sizewell B

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Economics of cleanup

• Nuclear decommissioning is the

dismantling and decontamination

of a nuclear power plant site after

its lifetime (~25 – 60 years) is

reached so that it will no longer

require measures for radiation

protection.

• UK’s u lear de o issio i g has a a ual udget of ₤2 billion for

the next 25 years.

• The nuclear industry sold everyone in the UK 4 kWh/d for about 25

ears, so the u lear de o issio i g authorit ’s ost is a out .

pence/kWh.

Sizewell A is being defueled and decommissioned!

28 Source: Xu Kuangdi , 2010

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Development of nuclear power in China

• Mainland China has 20 nuclear power reactors in operation spread out over 8 separate sites ,

28 under construction, and more about to start construction.

• Additional reactors

are planned,

including some of

the world's most

advanced, to give

more than a three-

fold increase in

nuclear capacity to

at least 58 GWe by

2020, then some

150 GWe by 2030,

and much more by

2050.

• Chi a’s policy is for

closed fuel cycle.

http://www.world-nuclear.org/info/Country-Profiles/Countries-A-F/China--Nuclear-Power/

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Operating nuclear plants

• Daya Bay, Ling Ao are close to Hong Kong.

• The Daya Bay reactors are standard 3-loop French PWR units with commercial operation in

February and May 1994. The plant produces about 13 billion kWh per year, with 70%

transmitted to Hong Kong and 30% to Guangdong.

• The Ling Ao Phase I reactors are virtually replicas of adjacent Daya Bay units. Ling Ao 1 & 2

entered commercial operation in May 2002 & January 2003.

• The Ling Ao Phase II reactors are transitional M310 - CPR-1000 units with Chinese design

and manufacturing. Unit 1 entered commercial operation in September 2010. Unit 2

commenced commercial operation in August 2011.

http://www.world-nuclear.org/info/Country-Profiles/Countries-A-F/China--Nuclear-Power/

31 * including new capacity at first three. Source: Red Book 2011.

Uranium resources and mining in China

• Chi a o lai s to e a ura iu -ri h ou tr o the asis of so e t o illio tons of uranium. By international standards, China's ores are low-grade and

production has been inefficient.

• Increasingly, uranium is imported from Kazakhstan, Uzbekistan, Canada, Namibia,

Niger and Australia. In 2012 imports were 12,908 tU, and in 2013 China imported

18,968 tonnes of uranium for $2.37 billion from five countries (Kazakhstan,

Uzbekistan, Australia, Namibia and Canada)

http://www.world-nuclear.org/info/Country-Profiles/Countries-A-F/China--Nuclear-Fuel-Cycle/

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China's Nuclear Fuel Cycle

• China is making major strides to become self-sufficient in most

aspects of the fuel cycle.

• Domestic uranium mining currently supplies less than a quarter of

China's nuclear fuel needs. Exploration and plans for new mines

have increased significantly since 2000, and state-owned

enterprises are also acquiring uranium resources internationally.

• China's two major enrichment plants were built under agreements

with Russia in the 1990s and, under a 2008 agreement, Russia is

helping to build additional capacity and also supply low-enriched

uranium to meet future needs.

• Chi a’s R&D i u lear te h ologies is se o d to o e i the world, particularly in high-temperature gas-cooled and molten

salt-cooled reactors.

http://www.world-nuclear.org/info/Country-Profiles/Countries-A-F/China--Nuclear-Fuel-Cycle/

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http://www.world-nuclear.org/info/Country-Profiles/Countries-A-F/China--Nuclear-Fuel-Cycle/

LEU – Low-Enriched Uranium; PWR – Pressurized Water Reactor; FBR – Fast Breeder Reactor;

CANDU – CANada Deuterium Uranium reactor; MOX – Mixed-OXide; RU – Recycled Uranium;

DU – Depleted Uranium; NU – Natural Uranium

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• Chi a’s u lear po er apa it i is a out GWe. 70 GWe are to

be added in 10 years, averaging 7 GWe per year.

80 GWe capacity in 2020 means at least 80 1GWe nuclear reactors.

• In the ten years from 2020 to 2030, adding120 GWe means adding 12

GWe per year on average.

• In the twenty years from 2030 to 2050, the average power added is 10

GWe per year.

• 400 GWe i is ore tha the orld’s total of 77 GWe (slide

30)

• China is rapidly becoming self-sufficient in reactor design and

construction, as well as other aspects of the fuel cycle.

http://www.world-nuclear.org/info/inf63.html

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