Decay heat calculations An industrial perspective Total, beta and - PowerPoint PPT Presentation

Decay heat calculations An industrial perspective Total, beta and γ -ray with JEFF-3.1 Presented by: Dr. Robert W. Mills, Nexia Solution Ltd Work supported by the UK Nuclear Decommissioning Authority Date: 17/ 7/ 06

Summary of presentation • Spent Nuclear Fuel Decay heat issues • Validation for transport, storage and reprocessing • Validation for short times • Thermal fission of U235: Total, ß and γ -ray • Uncertainties on U235 γ -ray summation calculations • Thermal fission of Pu239: Total, ß and γ -ray • Effects of Greenway TAGS. Fission of Pu239 (C. Dean, Serco Assurance Ltd supported by the UK Nuclear Decommissioning Authority) • Thermal fission of Pu241: Total • Fast fission of U238: Total Slide 2

Decay heat • This is the delayed heat released from components of nuclear systems after irradiation. • In reactors this is dominated by the fuel assembly components (includes heavy elements, fission products, and activation products) • Results from beta and alpha decay, internal transitions and spontaneous fission of nuclides present. • Includes: • photons (x-rays and gamma), • leptons (electrons and positrons) and • baryons (alpha particles, neutrons, nucleus recoil) Slide 3

Spent Fuel Decay Heat Issues • Important for • Reactor transient analyses • Reactor shutdown analyses • Removal of fuel from reactors • Storage of spent fuel • Transport of spent fuel • Reprocessing of spent fuel • Data used can be from two sources • Summation calculations (e.g. FISPIN, DARWIN, ORIGEN, etc.) • Standards (usually developed from calculations) Slide 4

Spent Fuel Decay Heat Issues • Decay heat from fission products and heavy elem ents ( Z> 8 0 ) Slide 5

Spent Fuel Decay Heat Issues • delayed heat from fission products from a single fission in a therm al reactor neutron flux ( JEFF-3 .1 calculations) minute hour month year decade day Slide 6

Validation for transport, storage and reprocessing • PW R fuel decay heat experim ental data and calorim etric results ( zircalloy clad fuel only: stainless steel clad fuel gave no cobalt content) F. Schmittroth, "ORIGEN2 Calculations of PWR spent fuel decay heat compare with calorimeter data." Report HEDL-TME 83-32 UC-85 (1984) and references therein. Slide 7

Validation for transport, storage and reprocessing • PWR validation: Comparisons with experiments From JEF/ DOC-1109, R.W. Mills Preliminary validation of the JEFF-3.1 fission yields and decay data by decay heat and fission product inventories. Slide 8

Validation for short times (~ 1-10 5 seconds) • Comparisons of inventory codes have shown there results are in agreement if using the same data: • B.F. Duchemin, C. Nordborg, "Decay Heat Calculation- An international nuclear code comparison" NEA report NEACRP- 319 "L" (1989). • Evaluations of decay heat have been prepared: • A. Tobias, "Decay Heat", Progress in Nuclear Energy, Vol.5, No. 1, pp.1-193 (1980). • A. Tobias, "Derivation of Decay Heat Benchmarks for U235 and Pu239 by a Least Squares Fit to Measured Data", CEGB report RD/ B/ 6210/ R89 (1989). • These used 54 sets of U235 measurements and 28 sets for Pu239 in the analyses. • Experimental data for other nuclides limited, but include • Pu241 thermal: J.K. Dickens, T.A. Love and J.W. McConnell, "Fission-Product Energy release for times following thermal-neutron Fission of plutonium-239 and plutonium-241 between 2 and 14000 seconds", Nuclear Science and Engineering, Vol. 78, pp. 126-146 (1981). • U238 fast: M. Akiyama et al, "Measurements of Fission-Product Decay heat for Fast Reactors” Proceedings of a Conference on Nuclear Data for Basic and Applied Physics", Sante Fe, USA (1985). Slide 9

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation ( β + γ ) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 10

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation ( β ) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 11

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation ( γ ) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 12

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation/ Evaluation ( β + γ) 1.200 1.150 1.100 1.050 1.000 0.950 0.900 0.850 0.800 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias uncertainty estimate Slide 13

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation/ Evaluation ( β ) 1.300 1.250 1.200 1.150 1.100 1.050 1.000 0.950 0.900 0.850 0.800 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias uncertainty estimate Slide 14

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation/ Evaluation ( γ ) 1.200 1.150 1.100 1.050 1.000 0.950 0.900 0.850 0.800 0.750 0.700 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias uncertainty estimate Slide 15

Validation for short times – U235 • U2 3 5 therm al neutron induced Calculation/ Evaluation ( γ ) including estim ate of uncertainty on calculation 1.300 1.200 1.100 1.000 0.900 0.800 0.700 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEFF31 Tobias uncertainty estimate Slide 16

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation ( β + γ) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 17

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation ( β ) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 18

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation ( γ ) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Tobias (1989) JEFF31 JEF-2.2 JEF1 Slide 19

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation/ Evaluation ( β + γ) 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias Slide 20

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation/ Evaluation ( β ) 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias Slide 21

Validation for short times – Pu239 • Pu2 3 9 therm al neutron induced Calculation/ Evaluation ( γ ) 1.200 1.150 1.100 1.050 1.000 0.950 0.900 0.850 0.800 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 JEF1 JEF22 JEFF31 Tobias Slide 22

Greenway TAGS – Effect on Pu239 results • Pu2 3 9 therm al neutron induced Calculation ( γ ) Private com m unication from C. Dean, Serco Assurance Ltd ( supported by the UK Nuclear Decom m issioning Authority) G a m m a E n e rgy from F P D e c a y - Pu239 0.60 0.55 0.50 Decay Heat t*f(t) (MeV/fission) 0.45 0.40 0.35 0.30 Tobias JEFF3.1 JEFF3.1 + Rudstam 0.25 JEFF3.1 + TAGS JEF2.2 0.20 1.0 10.0 100.0 1000.0 10000.0 T ime After Fission Burst (s) Slide 23

Greenway TAGS. Fission of Pu239 • Pu2 3 9 therm al neutron induced Calculation/ Evaluation ( γ ) Gamma Energy from FP Decay - Pu239 (As a ratio to the Tobias evaluation) 1.20 JEFF3.1 JEFF3.1 + Rudstam 1.15 JEFF3.1 + TAGS JEF-2.2 Tobias+ 1 s.d. 1.10 Tobias - 1 s.d. Decay Heat t*f(t) (MeV/fission) Ratio Calculated / Evaluated 1.05 1.00 0.95 0.90 0.85 0.80 1.0 10.0 100.0 1000.0 10000.0 Time After Fission Burst (s) Slide 24

Validation for short times - Pu241 • Pu2 4 1 therm al neutron induced fission pulse ( β + γ) Slide 25

Validation for short times – U238 • U2 3 8 fast neutron induced fission pulse ( β + γ) Slide 26