NEA Nuclear Data High Priority Request List, HPRL


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Request ID9 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-233 (n,g) nubar,SIG  Thermal-10 keV  .5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Molten Salt Reactors 19-APR-07 19-APR-07 

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Requester: Dr Adrien BIDAUD at LPSC, FR

Project (context): JEFF

U-233 is the main isotope of relevance to the Th/U fuel cycle. The present request concerns the viability of Th/U fueled molten salt reactors which requires that the amount of U-233 generated equals that which is destroyed.

0.5% in nubar, 5% for the (n,g) cross section

Justification document:
Uncertainties on the predicted regeneration gain inferred from the uncertainties of the nuclear data have been estimated showing a 4200 pcm uncertainty for a regeneration gain designed to be 200 pcm, i.e. very close to a complete balancing of production and destruction of U-233. The main culprits are nubar contributing 2200 pcm and the capture cross section contributing 3260 pcm. A target accuracy of 2000 pcm is required to facilitate defining the reprocessing scheme for a molten salt reactor.
A. Bidaud, Impact of Nuclear Data Uncertainties on a GEN IV Thorium Reactor at Equilibrium (attached document).
CEA Technical Note NT-SPRC/LEPH-05/204, G. Noguere et al (attachment 2).

Comment from requester:
Owing to the difficulty in measuring the U-233(n,g) cross section, a new evaluation could be done on the basis of the Profil results (see CEA Technical Note NT-SPRC/LEPH-05/204).

Comments from evaluator/experimentalist:
Any effort done to reduce the uncertainties on neutron yields and capture cross section down to less than 1% and about 5% respectively or at least to confirm their uncertainty would be very much appreciated. If the uncertainty on RG could be reduced down to 2000pcm, the needed reprocessing scheme could be designed with more confidence, and then the research on specific goals such as minor actinide and protactinium extraction could be prioritized.

Comments for achieved accuracy:
Nubar is currently known to 1%, the capture cross section to 10%. The above mentioned target uncertainties implies that the desired accuracies for improved data are approximately half these numbers.

Review comment:

Additional file attached: U233_MSR_Impact.pdf
Additional file attached: NT-Profil.pdf