NUCLEAR REACTORS. Nuclear Fuel Pellet Cost $3 ~ 7 g total, with ~ 0.3 g 235 U Energy equivalent: 1 ton coal

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Berniece James
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1 NUCLEAR REACTORS My use in U City = 200 kwh/mo/person => 0.3 kw continuous (= 3 *100-watt bulbs) per efficiency, could be supplied by 0.3 g 235 U/y or 1 ton of coal/y Nuclear Fuel Pellet Cost $3 ~ 7 g total, with ~ 0.3 g 235 U Energy equivalent: 1 ton coal

2 To supply a 1000 MWe power plant for a day, assuming a realistic 38% efficiency, need either: or 2.7 kg 235 U 10,000 tons = 10 7 kg of coal! Unit Train: tons ea

3 E = mc 2 Einstein (1905) Annihilate 1 g => E = (0.001 kg)(3x10 8 m/sec) 2 = 9 x joules 15,000 bbl of oil or 3300 tons of coal Annihilate 1 lb => E = kwh = USA electrical needs for 1.1 days = drive car 300,000 times around the Earth Curve of Binding Energy/nucleon (= protons & neutrons) Release Energy by Fusion of light elements Fission of heavy elements

4 fission

5 FUSION Need ~ 10 7 K! Very little radwaste- products not radioactive Some produced by neutron bombardment of reactor parts Princeton Tokamac: 12/93 (Jan 94 Physics Today) 50:50 DT rxn: 2 H + 3 H => n (14 MeV) + 4 He (3.5 MeV) 6.4 MW released, but 24 MW went in! The deuterium in ~10 km 3 of seawater would, if all fused, provide energy equal to the pre-industrial fossil fuel supply of the entire world. Deuterium in total ocean has an energy value of >100 million times that of the world's pre-industrial fossil fuel supply. Energy supplies practically unlimited if we could use 1 H!

6 Nuclear Binding Energy of Alpha Particle Hill & Petrucci

7 HYDROGEN BURNING (fusion): Thermonuclear reaction for Main Sequence stars. CNO Cycle Net Reaction: 4 1 H => 4 He + 7 ϒ + 2 ν MeV E = (4 * ) = MeV T ~ 10 7 K required Every second the Sun: Consumes Produces Difference million metric tons of H million metric tons of He 4.34 million metric tons of matter = 3.9 x J of energy! => Solar luminosity = 3.9* Watts

8 NUCLEAR FISSION Discovered by German radiochemists Otto Hahn & Fritz Strasmann (1938) Bombarded Uranium with neutrons, produced Ba- had split atom! Fission of a heavy atom produces: 2 neutron-rich product nuclei of unequal size with z=30 (Zn) to z=65 (Tb) 2.5 neutrons on average Alpha particles (α) 200 MeV (= 32 pj /atom) => Neutron-rich product nuclei emit b - ' s in complex decay series FISSION produces ~200 MeV/atom => x (1.602 x J/eV )(6.023x10 23 )(1 g/235) = 8.2 x J/g 235 U (cf. mc 2 = 9 x J/g) Fission 1 g of 235 U, 239 Pu, or 233 Th = 8.2 x J/g. = heat of combustion of 13.4 barrels of crude oil = heat of combustion of ~2.7 metric tons of coal (wt. ratio = 1 : 2.7 x 10 6 ). 235 U only natural material fissionable with slow neutrons 239 Pu made in breeder by neutron bombardment of non-fissionable 238 U 233 Th made in breeder by neutron bombardment of non-fissionable 232 Th

9 235 U Fission

10 A=95 A =137 U-235 Thermal Neutron Fission Products A=118

11 TYPICAL FISSION REACTIONS & subsequent b- decay events of products 1 n U => 236 U* => 144 Ba + 89 Kr n 144 Ba => 144 La => 144 Ce => 144 Pr => 144 Nd (long lived) 89 Kr => 89 Rb => 89 Sr => 89 Y (stable) 1 n U => 236 U* => 140 Xe + 94 Sr n 140 Xe => 140 Cs => 140 Ba => 140 La => 140 Ce (stable) 94 Sr => 94 Y => 94 Zr (stable)

12 NUCLEAR BOMB Exceed critical mass Get uncontrolled chain reaction = Explosion Flash Fireball Blast Fallout ndep.nv.ogv

13 Nuclear chain reaction N.J.Tro

14 NUCLEAR REACTORS Enrico Fermi Concept of controlled chain reaction First nuclear reactor CP-1 (1942) Controlled Nuclear reaction: Achieve & maintain criticality (cf. bomb) StLPD 11/21/12

15 Controlled, Sustained Chain Reaction 235 U + n = fission products + absorbed n free n MeV

16 Oklo Mine, Gabon, West Africa 1.7 Ga EIA

17 Callaway Nuclear Plant Missouri 1190 MWe PWR Ameren Missouri

18 NUCLEAR REACTORS: World 450 nuclear reactors in ~31 countries USA 99 France 58 Many different designs USES: FUELS: Power Generation Neutron sources Radioisotope production Unenriched U (natural ab: U 0.71% 235 U) Enriched U (typically 4-6% 235 U) Highly enriched (e.g., 47% 235 U) Other (e.g., artificially produced, fissionable 239 Pu; 233 U)

19 World s Nuclear Reactors

20 eia

21 Now none USA objects/602/616516/chapter_22.html

22 REACTOR COMPONENTS Fuel Elements: ceramic coated 235 U enriched pellets (< 1 cm dia) Fuel Rods 12' long, have metal cladding, packed into Fuel assemblies: ~ 15x15 = 225 rods Reactor has ~200 assemblies/reactor (typically > 70 tons of U) Self moderating fuel element - pellets have very hi thermal expansivity- EBR II research breeder (U-Pu-Zr alloy) MHTGR- hi T- U C SiC pellets (stable to 1800 C- can withstand total coolant loss) Moderator (slows neutrons- thermal neutrons easily captured) e.g., graphite, Be, D 2 O, H 2 O Control Rods (= neutron absorber; e.g. cadmium; boron steel) Coolant LWR s light water reactor Most in USA; two subtypes PWR's (pressurized) & BWR's (boiling) HWR s Heavy water (more effective moderator) Candu reactors- can use natural U as fuel Liquid Na or K = Breeders He gas (unreactive!) AGR's (advanced gas-cooled) HTGR's (high T gas-cooled)

23 Nuclear Fuel Pellet Cost $3 ~ 7 g Energy equivalent: 1 ton coal ~10 7 pellets in power plant

24 DOE

25 PWR Fuel Assembly A 1000 MWe reactor has ~200 fuel assemblies that contain about ~75 tons U

26 BWR Boiling Water Reactor

27 PWR Pressurized Water Nuclear Reactor

29 BREEDER REACTORS: can produce more fuel than consume! Neutron bombardment produces either: Fissionable 239 Pu from non-fissionable 238 U Fissionable 233 U from non-fissionable 232 Th Breeders have: Small core Very highly enriched fuel Na coolant (molten; need hi T) No moderator: hi T so capture fast neutrons France: Super Phenix 1200 MWe commercial breeder (Craig et al. p. 131)

30 FBR No moderator Hi T- Na cooled Pu core, 238 U rods 1.2 Pu atoms are formed for each Pu atom consumed

32 Super Phenix Fast Breeder 1200 MWe

33 PROBLEMS Nuclear Accidents Lack of Standardization Reactors do not go up as nuclear explosions Reactors get hot, have chemical explosions 21 uncontrolled reactions since 1953 (US News 10/11/99 p. 44) Chalk River, Ottawa, Canada (12/12/52) Accidental removal of 4 control rods Partial meltdown; no injuries Windscale, England (10/7/57) Fire, radionuclide release Tokiamura nuclear processing plant, Japan 9/30/99. Mixed 7x too much in nitric acid (~35 lbs U) => blue flash 200 trains stopped, 241 schools closed, 10k people checked; >100 exposed; 2 fatalities

34 Kyshtym, South Urals, USSR (ca. 3/1958) Explosion Release of reprocessed fission wastes from weapons plant? Large evacuation >100 km 2 contaminated; red dust & defoliation; Techa R water highly radioactive Trabalka et al. (1979) Oak Ridge Env.Sci. Pub. #1445 Three Mile Island, Harrisburg, PA (3/28/79) PWR Pump failure Valves on backup pumps improperly left closed Coolant loss Core Expose Partial meltdown Ci (5.5 x10 11 Bq) released ( 131 I; 8 day half life)

35 Three Mile Island, PA (undated) DOE

36 Chernobyl, Ukraine (4/26/86) 95 tons of avg. of 610 reactor days. Demand surge during a Test: No equipment failure Workers violated procedures, removed all but 8 control rods to inc. power Reactor went out of control in ~ 3 sec. Zr in fuel elements reacted w/ water, released H 2 gas that exploded Core housing ruptured, roof lifted, Fire Hot lumps of graphite & uranium oxide fuel thrown out; ~ 10% of core material dispersed into atmosphere. Core temp continued to increase for at least 9 days. Plume with 131 I (8 days), 134,137 Cs, 89,90 Sr, 141,144 Ce, Pu moved northwest 50 MCi = 10 6 x TMI Affected entire northern hemisphere. 31 fatalities; 237 cases acute radiation sickness; 1800 cases thyroid cancer 20,000 people received 250 msv (25 rem) ; 200,000 got 100 msv (10 rem) 200,000 relocated from 4,300 km 2 exclusion zone No increase in leukemia seen to 2004 $15 billion in damage. Partly as a consequence, much of Europe has halted new nuclear construction: Sweden, Spain, Netherlands, West Germany, Yugoslavia, UK, Switzerland

37 Chernobyl

40 Chernobyl sarcophagus 275 m wide x 108 m high NYT 4/28/14

41 Fukushima Daiichi, Japan (3/11/2011) #2 M8.9 Earthquake, 15m Tsunami Emergency generators failed Pump failures, Coolant Loss PWR Reactors 1-3 overheated, meltdown Explosions Radionuclide Release (24 MCi ~ 900PBq) More explosions, Spent fuel (>1500 rods) in Unit 4 exposed Evacuation of >150,000 people Permanent evacuation of 12-mile radius Planned phase out of Japan s nuclear power industry

42 Natori, Miyagi prefecture M 9.0 EQ 230 miles NE of Tokyo, depth 17 miles March 11, 2011 NYT 3/11/11

43 Fukushima Daiichi nuclear power plant Nov 15, 2009 NYT

44 Fukushima Daiichi nuclear power plant March 14, 2011 NYT

45 Fukushima- spent fuel pool, Reactor #4 NYT 11/13/11

46 Fukushima- desertion within 12 mile limit NYT 11/13/11

47 Financial Problems Delays, Regulations, Permits, Cost Overruns LILCO Long Island Lighting Co., Shoreham Plant- Controversy, Administrative delay $300 million est. cost in > $5.5 billion when completed in 1984 Never produced power Sold to state for $1 in return for rate increase WPPS Washington Public Power Supply System 115 utility consortium Defaulted in 1983 on $2.25 billion in municipal bonds In USA: ~70 Utility lawsuits against fed for no waste removal; totaling several $B Maine Yankee won $82M settlement 10 plants need to be decommissioned, at $1 B each 12 failed nuclear projects have caused near financial ruin for the utilities Many investors would now sell stock if nuclear construction plan were announced by utility

48 USA 104 => 99 reactors in 31 states 19% of electricity, 6 states dominantly nuclear, 33 states dominantly coal VT (80%) SC ME VA NY CT Reactors- numerous designs, run by > 50 different utilities Radwaste- spent fuel reactor sites- no reprocessing DOE has spent >$ 13 billion on plans for repository No 4 construction permits Number of operating reactors & nuclear generating capacity shrinking France 58 reactors 76% of electrical power Mostly, single design (PWR); minimal siteing problems Electricite de France (EDF) Government-owned utility Recycling of spent fuel, separating U & Pu

Nuclear Issues 5. Decline of Nuclear Power? Three Mile Island Chernobyl Waste Disposal

Nuclear Issues 5. Decline of Nuclear Power? Three Mile Island Chernobyl Waste Disposal Nuclear Issues 5 Decline of Nuclear Power? Three Mile Island Chernobyl Waste Disposal Decline of Nuclear Power? Nuclear has been on the wane worldwide Ditto the US Many countries are now reconsidering