Nuclear Fuel Production Fissile Nuclei Uranium and Plutonium

Nuclear Fuel Production Fissile Nuclei Uranium and Plutonium 235 U 239 Pu

Uranium Two isotopes 99. 3% 238 U 0. 7% 235 U not useful for energy production For a nuclear reactor: Need 4% For a fission bomb: 235 U Need 90% 235 U

Reacting the Fuel: Fission Reactions

Chain Reactions

Controlling the Reactions: Control Rods

Producing Uranium Fuel U ore contains small amounts of UO 2 and UO 3. Step 1. Oxidize UO 2 to UO 3 Step 2. Solubilize U by reacting with H 2 SO 4 UO 3(s) + 2 H+(aq) UO 22+(solid salt) + H 2 O(l) UO 22+(solid salt) + 3 SO 42 -(aq) UO 2(SO 4)34 -(aq) Key: Uranium is solubilized and is leached out of the rock.

Step 3. More Reactions, eventually to yield UO 3. 2 R 3 N + H 2 SO 4 (R 3 NH)2 SO 4 2 (R 3 NH)2 SO 4 + UO 2(SO 4)34 - (R 3 NH)4 UO 2(SO 4)3 (aq) + 2 SO 42 - (aq) (R 3 NH)4 UO 2(SO 4)3 + 2(NH 4)2 SO 4 4 R 3 N + (NH 4)4 UO 2(SO 4)3 + 2 H 2 SO 4 2 NH 3 + 2 UO 2(SO 4)34 - (aq) (NH 4)2 U 2 O 7 (s) + 4 SO 42 - (aq) (NH 4)2 U 2 O 7 (s) U 3 O 8(s) + H 2 O(l) + NH 3(g) U 3 O 8 is then reacted to make pure UO 3. Key: UO 3 formed is pure.

Step 4. Formation of UF 6 UO 3(s) + H 2(g) ====> UO 2(s) + H 2 O UO 2(s) + 4 HF(g) ====> UF 4(s) + 2 H 2 O(l) UF 4(s) + F 2(g) ====> UF 6(l or g) Key: UF 6 has a boiling point near 50 o. C.

Step 5. Fuel-Level Enrichment: 4%

Efficiencies: Diffusion method = 1. 002/stage Final Fraction = 0. 70 x (1. 002)#cycles Calculate # cycles to make 4. 0% 235 U Calculate # cycles to make 90. 0% 235 U

Efficiencies: Centrifuge method = 1. 2/stage Final Fraction = 0. 70 x (1. 2)#cycles Calculate # cycles to make 4. 0% 235 U Calculate # cycles to make 90. 0% 235 U

Plutonium Fuel: Made inside Uranium Nuclear Reactors Fast neutron reactors (Also called fast breeder reactors)

235 U

Artificial Transmutations

Creation of Transuranium Elements

Radioactive Dating http: //pubs. usgs. gov/gip/geotime/radiometric. html#table First-order Reaction

Specifics for Dating of Earth and Previously Living Things Units of Radioactivity: Curie, Ci = 3. 7 x 1010 disintegrations/sec Becquerel, Bq = 1 disintegration/sec C-14 N-14 5730 years