Nuclear safety, radiation,

waste and reprocessing

Bryan Leyland MSc, FIEE(rtd), FIMechE, FIPENZ

Visit to nuclear facilities

In July 2011 I was one of 3 Kiwis invited to go on a

study tour of nuclear facilities for waste reprocessing,

concentration and shipping

The tour was organised to ensure that some people in

New Zealand would have a good understanding of the

processes involved in dealing with nuclear waste

Neither during the visit or since, has any pressure being

exerted upon me to “gild the lily”

Melox facility - France

Details at: http://insaf-net.org/mox_wg/AREVA.pdf

Re-processing at Melox

This plant is in the south of France.

Used uranium is recycled to produce Mixed Oxide Fuel

(MOX) a mixture of enriched uranium and plutonium

recovered from the waste (The plutonium is NOT

“weapons grade”)

We had to change into clothes that they provided and

we went through radiation detectors several times.

During the tour through the plant we absorbed 23

micro Sieverts of radiation. The flight to the UK would

have exposed us to about 100 times more

Reprocessing Recovers materials with high energy potential and

saves natural uranium

10% of France’s electricity generation is from

Mixed Oxide Fuel – MOX fuel

It reduces uranium consumption by 25%

Minimises high level waste

5 times reduction in volume

10 times reduction in radiation

Burns up plutonium

Write

Fuel pellets

and rod

Sellafield Nuclear Site – Great Britain

Details at: http://www.visitcumbria.com/wc/sellafield-nuclear-reprocessing-facility.htm

UK Store for high level waste

Shipping

The fuel from the Melox (MOX) plant in the South of

France and the wastes from Sellafield are shipped to

Japan via the Tasman Sea

They are assembled in 130 ton flasks and loaded into

a specialized ship capable of carrying 20 flasks

If high-level wastes are being transported, they send

two identical ships with only one carrying the waste

The ships also carry armed policemen

Fuel flask

Nuclear Power

The safest and most environmentally friendly

form of major power generation

safer than hydro, gas and coal fired

generation

cooling water is the only significant

environmental impact

The risks of power generation

Coal-fired power stations kill thousands of people from

emissions, accidents and mining disasters.

Dam failures have killed many people.

Gas-fired power stations have exploded and killed many

people. Others die during gas production

Nuclear power stations have killed about 45 people at

Chernobyl. None have - or will- die at Fukushima. No-

one died at Three Mile Island

Death rates

based on power

produced

Nuclear 0.04/TWh

161 deaths per

TWh (000GWh) 36/TWh

Death rates

based on

power

produced

Safety aspects of nuclear power

Reactors cannot explode like a nuclear bomb

Nuclear provides 17% of the world’s electricity

It has killed less than 100 people

most at Chernobyl

the equivalent of a Model T Ford

Nuclear waste gets less dangerous over time

Moderate levels of radiation are not dangerous

Banqiao Dam

Banqiao dam in China failed in

1975 killing >175,000 people

Yenisei

river • Krasnoyarsk

• 6000 MW

•

• Sayano-

• Shusenskaya

• 6400 MW

Lake Baikal

Concrete arch-gravity dam 242 m high

crest length 1074 m

The 6400 MW station

Single gantry crane lifts

all 11 spillway gates

The accident happened at 8:13:25 local time

75 lives were lost

Inside the powerhouse

Turbine runner

Generator rotor

We are continually exposed to radiation

Sunlight is dangerous in large quantities, good in

moderate quantities and we have vitamin D problems

with too little

Careful studies of people living in areas with high

natural radiation (>200 milliSieverts) and the survivors

of Hiroshima and Chernobyl show that below about 200

milliSieverts radiation is not dangerous

The limit for nuclear power stations is 1 milliSievert!

For most people, our highest radiation is experienced

during international flights and from x-rays

How dangerous is radiation?

Is radiation dangerouss?

There is evidence that

exposure to moderately high

levels of radiation gives some

immunity against cancer in

later life

the theory is that a high

dose of radiation stirs up

your natural resistance and

this serves you well in later

life

www.radiationandreason.com

Radiation safety levels

Regulations promulgated 50 years ago

assume that all radiation is dangerous

Ignored the fact that while too much sunlight

is dangerous, too little can also cause

problems

Recent research has shown that below a

certain level radiation is quite safe and may be

beneficial

How dangerous are low levels

of radiation?

Safe Dangerous Fatal

Death

rates

Regulated

levels are

~1 mSv

1000 mSv

is safe!

Long term cancer risk

Taiwan

Radiation from contaminated reinforcing steel Predicted total cancer deaths from radiation 56

Total cancer deaths from natural causes 186

Actual total cancer deaths 5

2.7% of general public rate

Iran Natural radiation at Ramsar at 260 mSv is 25 times higher than

the US EPA maximum. “Residents have healthier and longer

lives”

Are small doses of radiation good for you?

Natural radiation hotspots

• milli Gray

Average natural dose to all Iranians ~100

Dose in Ramsar, Iran ~10,000

Dose in Kerala, India ~2000

Dose in Guapari, Brazil 100~90,000

Taiwan

Chernobyl

Health effects

Chernobyl

If Chernobyl is an argument against modern reactors

the logical conclusion is that no-one should drive a

modern motorcar or travel in a cruise liner

the Model T Ford did not have seatbelts or 4 wheel

brakes

The Titanic did not have radar

Fukushima

Long term waste disposal

If a nuclear station is shut down and sealed off and no-

one enters, no-one will ever get hurt

A hydro station with a large dam requires active

monitoring and maintenance for ever

High level waste is dangerous but it is easy to shield

against the radiation

A natural nuclear reaction took place in Gabon 2 billion

years ago. It lasted for thousands of years and produced

the same wastes as a modern reactor.

Research shows that the waste material did not migrate

and eventually decayed.

Radiation levels

Tumour therapy > 40,000mSv per month

Healthy tissue gets > 20,000 mSv per month, ok

Suggested safe level 100 mSv per month,

50 times the evacuation level of 2 mSv per month

nuclear stations regulated to 0.1 mSv per month, 1

mSv/yr

We should accept nuclear radiation for the benefit of

society at levels known to be safe

Nuclear Power

In a nuclear power station, uranium undergoes nuclear

fission and generates heat

The heat is used to boil water and this, in turn, drives a

conventional steam turbine

The amount of heat is controlled by rods that control the

fission

When the fuel is depleted, it is taken away and stored

until it cools down and then either stored permanently

or reprocessed

Modern Nuclear Stations A new generation of modern, safe and simple nuclear

power stations is now available

Some of them are “inherently safe” and cannot suffer

a “meltdown”

Those that need emergency cooling no longer rely on

diesel generators

Thorium reactors are on the horizon. More efficient

and cannot melt down. Called the “chemist’s” reactor

because of unique challenges they face, they will

require extensive development and testing like

uranium fueled reactors have had for decades.

Westinghouse AP 1000

Under construction

in China and US

Passive

cooling

system

SuperSafe and Simple

GE/Toshiba development

10- 50 MW

No onsite refueling for

30 years

Passive safety

622 MW PRISM fast reactor

GE/Hitachi

• Burns used

uranium and

wastes from

conventional

reactors

• Rapid

construction -

36 months

• Passive cooling Reactor unit 1 Reactor unit 2

Steam

out

LFTR Thorium Reactor

• Very safe - fuel

is drained if it

gets too hot

• Runs on

Thorium

• Very high

burnup

• Little high level

waste

A Sustainable option

• Small, sealed intrinsically safe nuclear reactors

• GT-MHR 325 MW Hyperion 25 MW B&W 4x125

These reactors can realize the dream of distributed

generation - eliminating the need for new transmission lines.

Questions