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

Date: 17/ 7/ 06

Presented by: Dr. Robert W. Mills, Nexia Solution Ltd Work supported by the UK Nuclear Decommissioning Authority

Decay heat calculations

An industrial perspective Total, beta and γ-ray with JEFF-3.1

Slide 2

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 3

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 4

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 5

Spent Fuel Decay Heat Issues

• Decay heat from fission products and heavy elem ents

( Z> 8 0 )

Slide 6

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 day year decade month

Slide 7

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 8

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 9

Validation for short times (~ 1-105 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 10

Validation for short times – U235

• U2 3 5 therm al neutron induced Calculation ( β+ γ)

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 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 ( β)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 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 ( γ)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 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 13

Validation for short times – U235

• U2 3 5 therm al neutron induced Calculation/ Evaluation

(β+ γ)

0.800 0.850 0.900 0.950 1.000 1.050 1.100 1.150 1.200 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 ( β)

0.800 0.850 0.900 0.950 1.000 1.050 1.100 1.150 1.200 1.250 1.300 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)

0.700 0.750 0.800 0.850 0.900 0.950 1.000 1.050 1.100 1.150 1.200 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 16

Validation for short times – U235

• U2 3 5 therm al neutron induced Calculation/ Evaluation ( γ)

including estim ate of uncertainty on calculation

0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05

JEFF31 Tobias uncertainty estimate

Slide 17

Validation for short times – Pu239

• Pu2 3 9 therm al neutron induced Calculation ( β+ γ)

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 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 18

Validation for short times – Pu239

• Pu2 3 9 therm al neutron induced Calculation ( β)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 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 ( γ)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 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 20

Validation for short times – Pu239

• Pu2 3 9 therm al neutron induced Calculation/ Evaluation

( β+ γ)

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 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

( β)

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05

JEF1 JEF22 JEFF31 Tobias

Slide 22

Validation for short times – Pu239

• Pu2 3 9 therm al neutron induced Calculation/ Evaluation

( γ)

0.800 0.850 0.900 0.950 1.000 1.050 1.100 1.150 1.200 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05

JEF1 JEF22 JEFF31 Tobias

Slide 23

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

0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 1.0 10.0 100.0 1000.0 10000.0 T ime After Fission Burst (s) Decay Heat t*f(t) (MeV/fission) Tobias JEFF3.1 JEFF3.1 + Rudstam JEFF3.1 + TAGS JEF2.2

Slide 24

• Pu2 3 9 therm al neutron induced Calculation/ Evaluation

( γ)

Gamma Energy from FP Decay - Pu239 (As a ratio to the Tobias evaluation)

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.0 10.0 100.0 1000.0 10000.0 Time After Fission Burst (s) Ratio Calculated / Evaluated Decay Heat t*f(t) (MeV/fission) JEFF3.1 JEFF3.1 + Rudstam JEFF3.1 + TAGS JEF-2.2 Tobias+ 1 s.d. Tobias - 1 s.d.

Greenway TAGS. Fission of Pu239

Slide 25

Validation for short times - Pu241

• Pu2 4 1 therm al neutron induced fission pulse (β+ γ)

Slide 26

Validation for short times – U238

• U2 3 8 fast neutron induced fission pulse (β+ γ)