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Modeling of Photonuclear Modeling of Photonuclear Reactions & Reactions &
Transmutation of Long-Transmutation of Long-lived Nuclear Waste in lived Nuclear Waste in
High Photon FluxesHigh Photon Fluxes TRAMU@GSI
M.-L. GIACRI-MAUBORGNE, D. RIDIKAS, J.-C. DAVIDDSM/DAPNIA/SPhN, CEA/Saclay, F-91191 Gif/Yvette, France
M. B. CHADWICK, W. B. WILSONLos Alamos National Laboratory (T-16), Los Alamos, NM 87545, USA
giacri@cea.fr
Applications of photonuclear Applications of photonuclear reactionsreactions
• Production of RNB• Neutron production• Non-destructive characterization of nuclear waste• Detection of nuclear materials (235U, 239Pu)• Radioprotection of electron accelerators• Transmutation of nuclear waste
ContentsContents
1. Development of a photonuclear cross section library for CINDER’90 evolution code :
– use of the IAEA photonuclear evaluation library– use of HMS-ALICE and GNASH to complete the
library– use of GSI fission model for photofission-yields
2. Example: transmutation in photon fluxes for 90Sr, 237Np and comparison with neutron fluxes
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CINDER’90CINDER’90
CINDER’90 (LANL) – material evolution in neutron fluxes
Photonuclear activation data library is needed to extend it for photon fluxes
Similar efforts for proton induced activation will make CINDER a multi-particle activation code
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Cross sections of light nuclides are difficult to reproduce whatever the model
In HMS-ALICE model for light nuclides needs to be improved
HMS-ALICE : HMS-ALICE : Light nuclidesLight nuclides
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HMS-ALICE : HMS-ALICE : Heavy nuclidesHeavy nuclides
Good agreement for 208Pb
181Ta not as good : total absorption cross section has a different shape
Calculations for heavy nuclei are good enough to be use in CINDER’90
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HMS-ALICE : HMS-ALICE : Absorption cross Absorption cross sectionssections
HMS-ALICE model for absorption can not be employed for actinides - sum of two Lorentzians should be used
Work is in progress to change the absorption model for actinides in HMS-ALICE
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Photoabsorption new modelPhotoabsorption new model
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HMS-ALICE : ConclusionHMS-ALICE : ConclusionHMS-ALICE should be used with certain precaution for
photonuclear reactions
Our approach to prepare CINDER’90 library:– Use of the IAEA evaluations when available– Use of GNASH for nuclides of interest to get better accuracy – Complete the library with the HMS-ALICE predictions
Next improvements in HMS-ALICE will focus on:– Total absorption cross section model (new parameterization)– Inclusion of photo-fission yields (GSI fission model)
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GNASH : GNASH : 235235U andU and 239239Pu Pu Input: σabs from the IAEA evaluations
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Good agreement with experimental data for separate channels
GNASH : GNASH : 237237NpNp
We made a compromise between two experimental data to obtain a integral equal to 3.54 barn.MeV
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Data on σabs are inconsistent
We fix this value according to the total integral, using the systematic from the IAEA for neighbor actinides
GNASH : GNASH : 237237NpNp
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Good agreement for photoneutron production
Photo-fission evaluation between the two experimental data
GNASH : ConclusionsGNASH : Conclusions
GNASH is a powerful tool for photonuclear data evaluations
Good agreement with experimental data when the total absorption cross section is used as input
Might be very time-consuming to use GNASH to build the entire library.
However, it can be used to increase the accuracy of cross sections for some elements and actinides in particular
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Data on the photofission of 235U and 238U with Bremsstrahlung spectra very limited• a few mass and charge distributions, some isotopic yields• P/V ratios, <LM> & <HM>
Calculation procedure
• total absorption cross section (GDR parameterization)• fission-evaporation in competition (GSI model)• calculation of independent fission yields and residual nuclei
PhotofissionPhotofission YieldsYields
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• both bremsstrahlung and monoenergetic photons are tried • 15 MeV photons are equivalent to 25 MeV bremsstrahlung
Example: photofission of Example: photofission of 235235UU
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n + 234U or n + 235U at 6-8 MeV might be a good combination
More careful checks on charge and isotopic distributions to be done!
Search for the systematic from Search for the systematic from (n,fiss)(n,fiss)
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we’ve got a working model for photofission (still in validation process)
• preliminary results are encouraging but sensitivity due to different parameters still to be tested
• in the near future we will provide for a number of actinidesa) fission cross-section predictions b) mass, charge and isotopic distributions of FFs and
residual nucleic) delayed neutron yields and time-dependence; and
search for the systematic from neutron induced fission
Fission Yield : ConclusionFission Yield : Conclusion
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Example : Transmutation of Example : Transmutation of 9090SrSr
Irradiation
Decay
1 year irradiation in the flux of 1017.cm-2.s-1
7 years decay
Results are in agreement with T. Matsumoto NIM A 268 (1988) 234-243
Total activity decreases by 30% compared to the natural decay of 90Sr
The same result can be obtained with a flux of 1016 nth cm-2 s-1
At 1018 .cm-2.s-1 activity is decreased ~20 times.TRAMU@GSI 9/5/03 giacri@cea.fr
Example : Incineration by Example : Incineration by fission of fission of 237237NpNp
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5 %/year incineration:
- 5x1016 .cm-2.s-1
- 7x1014 nth.cm-2.s-1
- 2x1015 nfast.cm-2.s-1
1 year irradiation as a function of flux intensity
Transmutation : ConclusionTransmutation : Conclusion
• Transmutation by photonuclear reaction does not create elements heavier than the initial nuclei
• It tends to reduce the long term activity
• Photon fluxes need to be one to two orders of magnitude higher than neutron fluxes
Conclusion and perspectivesConclusion and perspectives
• Thanks to the photonuclear library (by now it includes ~600 isotopes), with CINDER’90 we can do activation analysis in photon fluxes
• The library will be more precise by improving predictive power of HMS-ALICe
• Fission yields still have to be added to the library
• The integrality of the library still needs to be validated-tested by dedicated experiments
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