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##### Undergrad. Certificate in Renewable Energy.

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**Undergrad. Certificate in Renewable Energy.**Deadline Monday, March 1 Five $1000 scholarships Raesi.colorado.edu/undergradcert**Too cheap to meter!**Power from nuclear fusion.**Nuclear Fusion**21H1 + 21H132He1 +10n1 31H2 + 11H0 Using 21H1=Deuterium (D), 0.015% of all the hydrogen in the oceans. Each reaction3.65 MeV (each fission200 MeV) (carbon atom combustion3 eV)**But--**• Two positives repel, and can come near enough to react only at high temperatures and pressure. “Thermonuclear” • Plasma– confined only by magnetic fields. • ITER=International Thermonuclear Experimental Reactor**ITER**• International Thermonuclear Experimental Reactor • D+D at 150 million deg C • 10 billion euros and counting • Maybe to operate in 2025 • Sustain 500 MW for 1000 sec**Points**+: no CO2, lots of deuterium, no fission waste, no runaway -: How to couple energy to the grid? Not heat. Keeping the reaction going- 24/7 Cost Activation- the neutrons hit the walls.**Right sized fission reactors**Do we have to build only giant plants? Capital cost, large components, large markets, not modular. Interest in smaller systems, same principles.**Review of Monday, Wednesday**Nuclear reactions such as fission must balance, in Z and N (and A=N+Z) Fissions per second= Joules/sec (Watts) / (Joules/fission) And each fission releases 200 MeV=200x106 x “eV/Joule” =?????**Weights**• You must balance grams in your equation, with 12 for carbon, 235 for 235U, etc, just like chemical reactions. • BUT-here we also use the information (200MeV) per atom, and we did not use the energy to burn one carbon atoms. • New concept-the mole. Use ratios: 12 grams of carbon hold 6.02x1023 atoms of carbon. 235 grams of 235U hold 6.02x1023 atoms of 235U. etc**So-**• Fissions per year, per second of 235U from power. • Weight from the ratio of that many atoms to 235 grams, which hold the 6.02x1023 atoms.**Half life.**By what factor is the 235U present at the forming of the earth, 4.5 billion years ago, decayed away? T1/2=0.7 billion years Count half lives=4.5/0.7=6.4 half lives. At six half lives, (1/2)6=1/64=0.0156 At seven half lives (1/2)7=1/128=0.0078 So we have about 1% of the original 235U. (found at 0.7% in ore)**Homework #7 due Monday March 1**• A typical fission reaction for uranium is • 1on1 +23592U 14313153I78 +AZ XX N +3 10n1, • where I is the element iodine. • (2) What are the atomic weight A, the atomic • number Z and the neutron number N for the • element XX in the specific fission reaction above, • one of many possible. • (7) If we fission I kg of 235U completely in one year, • at a plant efficiency of 30%, how many electrical GW • can we sell? • Each fission yields 200 x106 eV (200 MeV). 235 grams of • 235U hold 6.02x1023 atoms.**(4) The above specific process occurs with 2% probability.**If we fission one kg of 235U completely, how many grams of 131I are produced? • (5) 131I has a half life of 8 days. If I start with one gram of it, how much is left after 32 days? • (2) Why is 131I a special concern?**Next week**Monday- Comparison of electricity costs and suitability- fossil, solar, wind, nuclear…. Wednesday-Efficiency (chapter 7), CU steps Friday-Insulation