NEA Nuclear Data High Priority Request List, HPRL

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Request ID5 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 72-HF-0 (n,g) SIG  0.5-5.0 keV  4 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission LWR 28-APR-06 16-APR-07 

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Requester: Dr Gilles NOGUERE at CAD-DER, FR
Email: gilles.noguere@cea.fr

Project (context): JEFF

Impact:
In nuclear industry hafnium is used as neutron absorbing material to regulate the fission process. Interpretations of critical experiments with UOx fuel conducted by CEA in the AZUR zero-power reactors has shown systematic underestimation of the reactivity worth that may by attributed to an overestimated natural hafnium capture cross section in the epi-thermal energy range [1,2].

Accuracy:
Requested accuracy can be found in the CEA Report "Correlations entre données nucleaires et experiences integrales a plaques, le cas du hafnium", Jean-Marc Palau, CEA-R-5843 (1997). The target accuracy on the effective capture integral has to be lower than 4%

Justification document:
[1] David Bernard, "Determination des incertitudes liés aux grandeurs neutroniques d'interet des reacteurs a eau presurisee a plaques combustibles et application aux etudes de conformite", University Blaise Pascal, Clermont-Ferrand II, France (2001).
[2] G. Noguere, A. Courcelle, J.M. Palau, O.Litaize, "Low neutron energy cross sections of the hafnium isotopes", JEFDOC-1077.pdf, OECD-NEA, Issy-les-Moulineaux, France (2005).
[3] G. Noguere, A. Courcelle, P. Siegler, J.M. Palau, O. Litaize, "Revision of the resolved resonance range of the hafnium isotopes for JEFF-3.1", Technical note CEA Cadarache NT-SPRC/LEPH-05/2001 (2005).

Comment from requester:
Neither the JENDL3.3 nor the JEFF3.1 libraries, that were recently issued, solve the problem. In fact, this was observed for JENDL3.3 before the JEFF3.1 file was constructed. As a result the JEFF3.1 file has been produced with this problem in mind taken into consideration the recent data from Trbovich et al. obtained at RPI [3]. Finally, a 400 pcm underestimation remains that is likely due to interfering isotopic contributions in the resolved energy region. New high resolution measurements appear needed, and would be particularly valuable if they can distinguish the contributions of different isotopes.

Comments from evaluator/experimentalist:
Measurements on natural Hf were carried out by CEA at IRMM in the frame of the NUDAME (http://www.irmm.jrc.be/html/nudame/) transnational access scheme. Further work is planned at IRMM in collaboration with CEA, INRNE, U. Birmingham and Serco.

Comments for achieved accuracy:
Calculations on the AZUR configuration using the JEFF3.1 library give a Hf reactivity worth of about -300 pcm [2].

Review comment:

Additional file attached: JEFDOC-1077.ppt
Additional file attached: NT_Hafnium.pdf