The Economics of Sustainable Development A.A. 2012-2013

Lecture 3

Effects of the Fukushima nuclear accident on the transition to a sustainable energy system

Alessandro Vercelli

University of Siena

Impact and relevance

The Fukushima accident had a great impact on the public opinion for a few months but it is now almost completely forgotten by mass media

Its impact on the crisis, energy policy and the transition to a low-carbon economy has been greatly understated:

swing of the public opinion

powerful challenge to nuclear power {

revision of energy policy in many states

not only «safer, cheaper and cleaner»

repositioning of the nuclear power lobby {

also «necessary to sustainability»

The final impact is still uncertain but certainly relevant for the transition:

in any case significant factor of cost inflation that interacts with the crisis

2

Structure of the lecture

1. Introduction

2. Description of the accident

3. Reactions to the accident a): challenge to the future of nuclear power

4. Reactions to the accident b): the re-positioning of the nuclear lobby

and the likelihood of a new nuclear renaissance

5. Nuclear power generation: an intrinsically unreliable «critical process»

6. Advantages and disadvantages of nuclear power generation: a post-

Fukushima reassessment

7. Concluding remarks

3

DESCRIPTION OF THE ACCIDENT

Section 2

4

1st Part

The Complex dynamics

of nuclear reactors

The nuclear plant Fukushima1

5

The magnitude 9.0 Tohoku earthquake that struck Japan on March 11 2011, was the largest quake to strike the country and the world's fourth-largest earthquake in recorded history

This was the largest nuclear disaster since the Chernobyl’s in 1986, the only one with Chernobyl to measure Level 7 on the International Nuclear Event Scale

The earthquake triggered a ”scram” shut down of the three active reactorsThe ensuing tsunami stopped the Fukushima I backup diesel generators, and caused a blackout:

the subsequent lack of cooling led to explosions and meltdowns at three of the six reactors and in one of the six spent fuel pools

only prompt salt water flooding of the reactors could have prevented meltdown: delayed because it would ruin the costly reactors permanentlycommenced too late only after the government ordered it

Description 1

6

Evacuation zone

On day one of the disaster nearly 134,000 people who lived between 3–20 km from the plant were evacuated. 4 days later an additional 354,000 who lived between 20–30 km from the plant were evacuated

7

Radiation deliberate venting to reduce gaseous pressureRadiation from { deliberate discharge of coolant water into the sea

accidental or uncontrolled explosions and meltdowns  The Japanese government estimates the total amount of radioactivity released into

the atmosphere was approximately one-tenth as much as was released during the Chernobyl disaster (revised up to ½ by recent studies)

butterflies captured near Fukushima have an unusual number of genetic mutations, and the deformities appear to increase through succeeding generations

According to a report published in October 2011 by the French Institute for Radiological Protection and Nuclear Safety, the emission of radioactivity into the sea is the most important ever observed

scientists monitoring sea life in the region have reported that a fish caught near the plant has radiation levels more than 2,500 times the limit established for seafood by the Japanese government

8

Nuclear fallout map

9

Radioactive Seawater Impact Map

10

Casualties

(the earthquake and subsequent tsunami caused about 20,000 casualties)

According to a June 2012 Stanford University study by John Ten Hoeve and Mark Jacobson, the radiation released could cause 180 cancer cases (the lower bound being 24 and the upper bound 1800), mostly in Japan;

there were no immediate deaths due to direct radiation exposures, but at least six workers have exceeded lifetime legal limits for radiation and more than 300 have received significant radiation doses; radiation exposure to workers at the plant was projected to result in 2 to 12 deaths

An additional approximately 600 deaths have been reported due to plant-related non-radiological causes such as mandatory evacuations

due to the disruption of hospital operations, exacerbation of pre-existing health problems and the stress of dramatic changes in life

11

REACTIONS TO THE ACCIDENT A): CHALLENGE TO THE FUTURE OF NUCLEAR

POWER

SECTION 3

12

Reactions to the accident a): swing of public opinionJapan

Before most citizen favorable to an increasing share of nuclear power generation

After an Asahi Shimbun poll found that 74% wanted a nuclear-free Japan

USA

The growing acceptance of nuclear power in the US was eroded sharply: only 43 % of those polled after the accident said they would approve building new power plants

Germany

In March 2011, more than 200,000 people took part in anti-nuclear protests in four large German cities

Italy

The growing acceptance of nuclear power was dramatically reversed after the accident as confirmed by the referendum of June 2011: 94% of votes expressed against the construction of new plants

France

Opinion polls indicated that 55% of the population were still in favor of nuclear power just after the accident but 57% against it by the end of March

. 13

Reactions to the accident a): change of policy

Japan The incumbent Prime Minister Naoto Kan announced a dramatic change of direction in energy policy promising to make the country nuclear-free by the 2030s; in the meantime: no new nuclear power plant, 40-year lifetime limit on existing plants, tougher safety standards enforced by the new independent regulatory authority

Germany On the 6 Aug. the Government decided to shut down 8 reactors and to decommission the other 9 by the end of 2022

Merkel: "[ we do not] only want to renounce nuclear energy by 2022, we also want to reduce our CO2 emissions by 40 percent and double our share of renewable energies, from about 17 percent today to then 35 percent"

Italy After the 1987 referendum the government phased out existing plants

2008: the government approves the construction of 10 new plants

After the Referendum of June 2011 a new construction ban of new nuclear plants implemented by the government

 Switzerland and Spain have also banned the construction of new reactors14

REACTIONS TO THE ACCIDENT B): THE REPOSITIONING OF THE NUCLEAR

LOBBY AND THE LIKELIHOOD OF A NEW NUCLEAR RENAISSANCE

SECTION 4

15

A new nuclear renaissance?Long-run cycle of fear (as in finance, see Minsky):

In the 1950s the fear was widespread because it was an untried technology evoking nuclear weapons but in the 1960 and 1970s the fear started to subside (apart from an active minority organizing impressive demonstrations)

The accidents of three Miles island (1979) and Chernobyl (1986) rekindled widespread fear that relented in the late 1990s and the first decade of the century until Fukushima (Nuclear Renaissance)

Japan

The new Prime Minister Abe was elected on 26 December 2012 and immediately said he was in favor of building new nuclear reactors

UK

Trebling of total installed capacity by 2050

China

has 25 reactors under construction to be added to the 14 already in service, providing a fivefold increase in nuclear-power generation capacity by 2020

India

will proceed with plans to order as many as 21 nuclear reactors

16

OECD IEA: decarbonization

17

18

“even if renewable and clean-fossil technologies meet extremely optimistic assumptions, a global clean-energy revolution adequate to avert catastrophic climate change will require an enormous contribution from nuclear power and extensive realization of its worldwide growth potential”

(World Nuclear Association)

19

World Nuclear Association: the long-term vision

20

NUCLEAR POWER GENERATION: AN INTRINSICALLY UNRELIABLE

«CRITICAL PROCESS»

SECTION 5

21

The intrinsic unreliability of the process of nuclear power generation

We cannot understand the causes and implication of the Fukushima 1 accident without understanding the fundamentals of nuclear power generation

It is based on the fission of heavy nuclides that triggers a self-sustaining chain reaction

The trouble is that this chain reaction is a structurally unstable process that should be kept always at (or very near) its critical value

This is very difficult and may become easily impossible under unusual circumstances that may easily occur

22

The microphysics of nuclear reactors: the nuclear fission

nuclear energy generationNuclear fission {

nuclear weapons

Microphysics: when a heavy nuclide (or isotope) is hit by a neutron its nucleus breaks into two or more “fission fragments” releasing a great amount of energy in the form of heat and radiation

The most important example for energy generation is that of uranium-235: when hit by a “free” neutron

235U + neutron → fission fragments + 2.4 neutrons + 192.9 MeV

23

The nuclear chain-reaction

The formula above shows:

• a nuclear reaction releases a great amount of energy: almost 200 millions of eV (electronvolts): hundreds of millions more than a chemical reaction

• each of the neutrons ejected may hit nearby nuclides triggering new fission events → nuclear chain reaction releasing a great amount of energy in a continuous way

• the trouble is that a nuclear chain reaction also releases dangerous

radioactive decay of fission fragmentsradiation {

energy in the form of radiation: gamma rays and neutrinos

24

The macrophysics of nuclear reactors

The challenge of nuclear engineering is the management of

produce great amounts of energy in a continuous way

nuclear plants able to {avoid any release of radiation outside the plants

This is very difficult since the optimal equilibrium is structurally unstable:

the analysis focuses on the dynamics of a population of free neutrons N

that reproduces itself according to the “effective neutron multiplication factor”

k=Nt+1/Nt ( 1 )

expresses the average number of neutrons released by one fission that bring about another fission

25

The dynamics of the core (discrete time)

we can express the dynamics of Nt :

Nt = kNt-1 + N’ ( 2 )

where N’ (exogenous flow of neutrons) is assumed constant and

k is the effective multiplication factor and plays a crucial role:

when k<1, the system is subcritical and cannot sustain a chain reaction:

→ the system is stable but the energy released rapidly fades away

→ the equilibrium number of free neutrons N* is given by:

N* =N’/(1-k), ( 3 )

where 1/(1-k) may be defined as the” multiplier” of exogenous neutrons that determines the equilibrium population of neutrons

(Szilard influenced by economics?)

26

The criticality of a nuclear reactorwhen k>1 the system is supercritical:

the chain reaction increases exponentially the number of fissions and thus also the population of neutrons

→ this progressively amplifies the energy released in a growingly uncontrollable way

The chain reaction may be exploited for a sustainable production of energy only in the borderline case:

when k=1 the system is critical: the number of free neutrons remains constant in a stationary process of energy release

The only useful state of the core is thus a structurally unstable

bifurcation path

27

Graphical representation

The dynamic behaviour of the reactor’s core under the three different hypotheses mentioned above may be represented in a simplified way as in the graphs 1a,b,c

we measure on the ordinates axis Nt+1 and on the abscissa axis Nt

the equation ( 2 ) has a slope that depends on k,

while the locus of possible equilibrium values (stationary since the exogenous neutron generation rate N’ is constant) is represented by the line at 45 degrees (where Nt+1=Nt)

28

29

Fig.1 The dynamic regimes of a nuclear reactor

Nt+1 Nt+1 Nt+1

Nt Nt NtN*

a) subcritical case: k<1 b) critical case: k=1 c) supercritical case: k>1

The determinants of kThe fine tuning of k is very difficult since the physical processes underlying the aggregate

value of k are probabilistic and are subject to complex dynamics

The parameter k depends on the following factors:

k = Pi Pf η - Pa - Pe ( 4 )

Where:

Pi is the probability that a particular neutron strikes a fuel nucleus Pf is the probability that the stroked nucleus undergoes a fission η is the average number of neutrons ejected from a fission event (it is between 2 and 3 for the typical fuel utilized in nuclear plants: 235U and 39Pu)

Pa is the probability of absorption by a nucleus of the reactor not belonging to the fuel Pe is the probability of escape from the reactor’s core.

In other words, the product of the first three variables measures the strength of the fission chain reaction, and thus of the energy release,

while the probability of absorption and escape measure the average leakage

30

Fluctuations of k and regulation

In consequence of the probabilistic nature of its underlying process, k necessarily fluctuates off its critical (desired) value:

“the system is never in equilibrium”

K < 1 → the efficiency in energy generation declines,

K > 1 → exponential increase in energy generation in the form of heath and radiation: this may easily jeopardize the safety of the reactor

→ a nuclear reactor requires reliable regulation mechanisms that keep the average fluctuations of k at the critical value while containing their amplitude

31

Typical BWR nuclear plant

32

Typical BWR nuclear reactor of the Fukushima1 type

Core: where the nuclear fuel bars are contained and the nuclear chain reaction occurs

Moderator (water): to slow down the chain reaction

Control rods: to regulate and control the chain reaction 33

Active regulation

The crucial active regulation instrument is given by “control rods”:

a small shift of a control rod inward or outward the reactor core produces a swift change in the number of fission events

Control rods are good enough for routine

however the criticality of the dynamic process implies that the reaction to unexpected contingencies may trigger a sequence of events that makes the reactor uncontrollable

e.g. the accident occurred at the Chernobyl Nuclear Power Plant:

a system test meant to improve safety led to a rupture of the reactor vessel and a series of explosions that destroyed reactor 4

34

Self-regulation: passive safety mechanisms

High probability of regulation mistakes under unexpected events:

→ passive safety mechanisms, i.e. independent of human decisions

a crucial mechanism of self-regulation is provided by the moderator: most moderators become less effective with increasing temperature → if the reactor overheats the chain reaction tends to slow down

e.g. regular water, that is used as moderator in the majority of reactors, starts to boil sizably reducing the effective

multiplier

however self-regulation may fail: e.g. there may be an unexpected leakage of water or steam or a failure of the system to pump new water into the reactor as in the case of Fukushima1

35

“Redundant” passive security mechanisms

In case of a mechanism failure the same role may be played by another one:

redundancy would increase safety iff failure probability of passive mechanisms were independent;

unfortunately their failure probabilities in consequence of a major shock may be not independent

Fukushima1, e.g., endured the earthquake in March 2011 but had its power and back-up generators knocked out by a 7- meter tsunami

lacking electricity to pump water needed to cool the core, engineers vented radioactive steam into the atmosphere to release pressure, leading to a series of explosions that blew out the concrete walls around the reactors

back-up diesel generators that might have averted the disaster were positioned in a basement, where they were submerged by sea water

36

After Fukushima1

The French Atomic Energy Agency (CEA) admitted that technical innovation cannot eliminate the risk of human errors in nuclear plant operation

An interdisciplinary team from MIT estimated that, given the expected growth of

nuclear power from 2005 – 2055, at least four serious nuclear power accidents would be expected in this period: Fukushima1 is only the first

After Fukushima deep and extensive revision of energy policy:

-many countries stopped construction of new plants including Germany, Italy, Switzerland and France-all the other countries are revising and severely downsizing the programs of construction of new plants including Japan, USA and the UK

Although the disruptions provoked by the Great Recession are not inferior, the financial system and regulation policies did not undergo a similar process of radical revision

37

ADVANTAGES AND DISADVANTAGES OF NUCLEAR POWER GENERATION:

A POST-FUKUSHIMA RE-ASSESSMENT

SECTION 6

38

Policy implications: arguments pro nuclear energy

a) safer: less casualties and radiation than with fossil fuels

Relatively { b) cheaper: less expensive than with renewables and

non-conventional fossil fuels

c) cleaner: GHGs emissions much less than fossil fuels and

similar to renewables’

This deliverable is not supposed to survey this immense literature but only to discuss what impact may be expected from the Fukushima accident:

negative impact on a) and b) → the burden of the pro-nuclear stance shifts on c)

39

Safer

In a meta-study of 2002 the International Energy Agency

“put together existing studies to compare fatalities per unit of power produced for several leading energy sources.

The agency examined the life cycle of each fuel from extraction to post-use and included deaths from accidents as well as long-term exposure to emissions or radiation.

Nuclear came out best, and coal was the deadliest energy source` (New Scientist)

40

Safer

41

Safer: deaths from energy-related accidents per unit of electricity

42

 source: Paul Scherrer Institut 1998, considering 1943 accidents with more than 5 fatalities.  One TW.yr is the amount of electricity used by the world in about 5 months.

Safer?

Correct stress on the heavy risks associated to the use of fossil fuel:

e.g.: over 30 thousand deaths have been attributed to US coal mining since the 1930's related to mining accidents and respiratory complications,

However, the belief in nuclear safety underestimates the number of casualties brought about by nuclear energy because:

-Difficult to establish the probabilistic cause-effect nexus even in the short run

-official estimates do not take into account the long-run effects of radiation on human health:

long latency: some cancers may take up to 40 years to develop

genetic consequences may become visible after many generations

-”exposure to radiation may disturb a number of other biological pathways: cardiovascular and immunological disorders…psychological disturbances: stress… depression and suicides…pathological changes in reproductive function…Down Syndrome” (EEA, 2013, p.5…)

43

Safer? Major incidents

Accidents under-reported and played down

Controversial UN agreement: IAEA has the right to veto any action by the WHO concerning health aspects of nuclear power (Karlsson, 2012, p.244)

Major nuclear incident =def one that either resulted in loss of human life or more than US$50,000 of property damage (US federal government) 100 major nuclear power plant accidents have been recorded since 1952, totalling more than US$21 billion in property damages

Nuclear industry claims that new technology and improved oversight made nuclear plants much safer, but 57 major accidents occurred since 1986

It was claimed that these accidents occurred in badly managed old-fashioned nuclear plants as in Chernobyl (1986);

however two thirds of these accidents occurred in the US and the worst of all, the Fukushima1 disaster, in the technologically advanced Japan using American technology (General Electric reactors)

44

Cheaper?

b) the favourable cost estimates are criticized for not taking full account of

- the entire life cycle of the plant

- the scarcity of the fuel similar to that of oil

- the external diseconomies

- the crucial role of an arbitrary high rate of discount

After each nuclear disaster, the bar is set higher for safety:

reactors built after the disasters at Three Mile Island in 1979 and Chernobyl in 1986 cost 95 percent more than those built before

about the same occurred after Chernobyl and will happen after Fukushima

The cost of power generated in plants built after the Three Mile Island accident was 40 % higher, and after the Chernobyl accident it increased an additional 40 %

45

Cheaper?: scarcity of high-grade uranium

Reserves from existing uranium mines are being rapidly depleted, and one assessment from the IAEA showed that enough high-grade ore exists to supply the needs of the current reactor fleet for only 40–50 years

Expected shortfalls in available fuel threaten future plants and contribute to volatility of uranium prices at existing plants

Uranium fuel costs have escalated in recent years, which negatively impacts on the viability of nuclear projects

46

47

Cheaper?

Cheaper? The construction costs of new plants already increasing before the Fukushima accident

48Source: Sokolski, 2010

Cheaper? The cost of renewables is decreasing

49

Cleaner?

a) estimates that take account of the entire life cycle of a nuclear plant, including its construction, its decommissioning, and waste disposal, find a much higher average level of GHGs emissions:

The (2010) meta-study by Sovacool’s research fellow at the National University of Singapore finds the following average emission values:

nuclear power; 66 gCO2e/kWh emissions

scrubbed coal-fired plants: 960 gCO2 e/kWh

natural gas-fired plants: 443 gCO2e/kWh

solar photovoltaic: 32 gCO2e/kWh

onshore wind farms: 10 gCO2e/kWh

He concludes: “For every dollar you spend on nuclear, you could have saved five or six times as much carbon with efficiency, or wind farms.”

50

TENTATIVE AND PROVISIONAL CONCLUSIONS

SECTION 7

51

Impact on the transition to a sustainable energy system

↑nuclear power

Increase in the price of energy {

↑fossil power

→ cost inflation jeopardizing the recovery from the crisis

→ energy from renewables became cheaper in relative terms

-nuclear renaissance unlikely in the absence of a technological

breakthrough

Transition {

-the case for massive investment in renewable energy greatly

strengthened

However the escape from nuclear energy should not be too rushed to avoid a spike in GHGs emissions

52