Nuclear Energy After Fukushima

Nuclear Energy After Fukushima

Frank H. Shu

Academia Sinica, UCSD, U Michigan 31 May 2011

HX Team: M. J. Cai, F. T. Luo, Y. D. Huang, P. Ho, R. Taam, S. Chien, B. Thompson, K. H. Chien, E. J. Wampler, T. S. Wei

Outline of Talk

•  Fossil Fuels and Climate Change

•  Limitations of Renewable Energy Sources

•  Nuclear Power after Fukushima

–  Safety of different nuclear fuel cycles –  Advantages of molten salt reactors

•  Application to biofuel production

•  Application to thermal-chemical dissociation of H₂O

•  Summary

H₂O

CO₂ O₃

H₂O

CO₂contribution to greenhouse

` 9 ^oC/33 ^oC

Lots of CO₂ No CO₂

Grand Challenge of 21st Century

“For millennia, until the discovery of fossil

fuels, the only way humans made

economic progress was to enslave other peoples.” (attributed to John Maynard Keynes)

•  According to James Hansen, tipping point for melting of polar ice is 350 ppm CO₂, which we passed in 1988.

Will add about 3 ^oC in radiative equilibrium

to pre-industrial revolution 9 ^oC

Share of World Energy

Generation in 2008 (IPCC)

Nuclear: 6% if thermal Renewable: 12.9% tot Wood: 6.3%

Biofuel: 4.2%

Hydro: 2.3%

Wind: 0.2%e0.5%t Geothermal: 0.1%

Direct solar: 0.1%

Myth: Nuclear is displacing renewable. Reality: Despite heroic levels of

investments, renewables are not displacing fossil fuels 38 yr after 1^st oil crisis.

Fossil vs. Renewables vs. Nuclear

•  Coal is a very concentrated form of chemical energy – 40 x Li ion battery per kg. Latter can be recharged ~ 1000 times, but costs ~ 8000 NTD/

kg. Coal is dirt cheap: only 3 NTD/kg.

Coal ~ 0.1 battery. Oil ~ 10 x coal.

•  Equipment for collecting, distributing,

& storing dilute sources of renewable energy will always be more

expensive than that which burns coal (stationary) or oil (transportation).

•  Nuclear energy in 1 kg uranium or thorium is 2.3 million times that

contained chemically in 1 kg coal.

Taiwan’s Choices

•  Present capacity 167 GW

•  Hydro: 0.2 GWe avg

•  Wind: max 3 GWe (avg)

•  Solar PV: 6 x coal = 50% GDP, 100% if want electricity at night

•  RE’s lack of market penetration because of intrinsic limitations

•  Realistic choices: nuclear or

fossil fuel (coal/oil/gas) or do w/o

•  “If you’re anti-nuclear and anti-

CO

, then you’re pro-blackouts”

Major Earthquakes since Nuclear Power in Taiwan

Locale Yr/Mag Deaths Property Nuclear Deaths Property Mexico 1985/8.1 10,000 4 GUSD Yes None None Armenia 1988/6.9 25,000 4 GUSD Yes None None USA, SF 1989/7.0 68 6 GUSD Yes None None JP, Kobe 1995/7.2 6,434 100 GUSD Yes None None Turkey 1999/7.6 17,127 20 GUSD Not yet None None TW,Nantou 1999/7.3 2,418 14 GUSD Yes None None In Ocean 2004/9.2 230,000 Unknown Yes None None CN,Szech 2008/8.0 68,000 86 GUSD Yes None None Chile 2011/8.8 486 25 GUSD Not yet None None

JP, Tohuku 2011/9.0 27,000* 300 GUSD Yes None? 30 GUSD

*Tsunami warning system; buddy system in schools; accelerometers on high- speed rail; elevators sent to ground fl; shutoff natural gas; make reactors safer

Fukushima: Long-Term Legacy

•  Low-level radiation (I-131 t

= 8 d; Cs-137 & Sr-90

= 30 yr) lasting decades w/o decontamination

•  To continue using nukes, make reactors safer, and eliminate human factors as much as possible

•  In case of accident, must contain I-131, Cs-137,

Sr-90.

20 mSv/yr = 13 x average Taiwan

= 1/5 x Ramsar Iran (radon)

Chain Reaction,

Breeding, Radioactivity

Fissile (odd number n):

U-235 (0.7% of U-238) U-233 from Th-232 + n Pu-239 from U-238 + n

n +

> 1 chain reaction

> 2 breed + 2 or 3 n

Th is 3 to 4 times more abundant in Earth’s

crust than U.

Problem: radioactivity &

decay heat of fission

products with t_1/2 ≤ 30 yr

U

Subcrit wrt prompt n Supercrit wrt delayed n

bigger σ with slow n;

collisions with moderator

- -

Nuclear fuel U-235 Pu-239 U-233

Fuel form Solid pellets Solid pellets Molten salt Burn-up 1% (net, stopped

by rad damage)

100% possible by refabrication

100% possible by circulation Waste storage 240,000 yr 300 yr, burn Pu-239 300 yr, only FP High-grade ore 6 yr if supply all 600 yr 2,000 yr

Moderator Water, slow n w absorption

None, fast n to breed

Graphite, slow n w/o absorption Coolant (usual) Water Liquid sodium Fluoride salt Number built 500 (civilian,

built > 30 yr ago)

15 (US, USSR, UK, Ger, Japan, India)

2 (ORNL, but made of metal)

Chernobyl: graphite moderator, water coolant,

Fuel Cycles

Armored Tank

MSRs Can Rid LWR Waste &

Safely Breed for U-233

•  LWR spent fuel

– U-238, U-235 – Pu/actinides – Fission prod’s

•  Th-232

Th-232 Blanket Ground

≥ 300 yr Enrich

& Reuse

Core

Chain reaction, breeding, & processing in liquid NaF-BeF₂

Taiwan has Th-232 in beach sand (monazite)

Pu in core turns Th-232 into

U-233 U-233 in core gives breeder

Two-Fluid Molten Salt Reactor

If over-heated, fuel salt

expands out of reaction zone.

Except for dump tank, system built from C-based materials

2 containment walls.

If T still rises, frozen plug melts; fuel salt drains into dump tank, which is air-cooled to remove decay heat (cannot lose air). Salt inert, low vapor P: no fire, no explosions.

Fuel not solid: no

radiation damage, no meltdown, no TMI.

Active/passive control

Patent Pending

Online

distillation of

fission products.

Circulate until 100% burn-up.

Spill: NaI, CsF, SrF₂ in salt that freezes in 10 s.

Thick steel dome, no Chernobyl, no Fukushima, no jet crashes. Burn Pu,

Use MSR Heat to Make Biofuel

High-throughput production of artificial coal, liquid biofuel,

& syngas for coal-fired power plants, heavy transportation,

& natural gas, preserving existing infrastructure (leverage each 1 watt nuclear power  7 watt biofuel)

Patent Pending

Taipower Assay:

Supertorrefied Bamboo

Quality Biocoal

Useful heating value 6139 kcal/kg (10 min at 300 C) Hargrove Grindability

Index

67

Sulfur content 0.06%

Ash content 5.69% (mostly potash = fertilizer) Moisture content 8.65% (depends on drying method) Partner CSBC & Taipower for equipment & commercial scale-up

Use MSR Heat to Make Water into a Fuel

Kloosterman, TU Delft

For H fuel

cells or liquid biofuel

For

carbon capture and

seques- tration

Summary

•  Saving the Earth is still possible, but it requires physicists to speak up & environmentalists to stop opposing nuclear power, the only C-free alternative that can replace fossil f’s.

•  The public is correct to insist on safe, affordable nuclear power with low proliferation risk and waste.

•  Not developing MSRs (the road not taken forty years ago) in parallel with LWRs was a big mistake.

•  Nuclear power plants must be evaluated on a realistic cost/

benefit basis. The risks are occasional accidents, but massive releases of radioactivity are preventable. The benefits are a much lower environmental footprint, energy security, and sustainable development for the millennium.