NEA Nuclear Data High Priority Request List, HPRL

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Request ID13 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 24-CR-52 (n,xd),(n,xt) SIG  Threshold-65 MeV  20 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fusion IFMIF, First wall 23-OCT-07 07-NOV-07 

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Requester: Dr Robin A. FORREST at CCFE, UK
Email:

Project (context): JEFF, EFF

Impact:
See attached report EFF/DOC-1015, "Preparatory work for the evaluation of Cr-52 high energy neutron data for EFF", P. Pereslavtsev.

Accuracy:
No experimental data are available for this reaction apart from one point at 14 MeV. Therefore, new experimental results with 20% accuracy are still valuable.

Justification document:
The reactions that need to be considered are Cr-52(n,d+n'p)V-51 and Cr-52(n,t+n'd)V-50. These are important both for modelling and for fusion technology applications. They are discussed in the UKAEA FUS 509 document (Handbook of activation data) available for download: ukaea-fus-509.pdf (8.6 Mb).

Comment from requester:
Attempts to measure the split in (n,d) and (n,np) to the production of 51V and the split in (n,t), (n,nd) and (n,2np) contributions to the production of 50V would be valuable.

Comments from evaluator/experimentalist:
In view of the stable end product both for the (n,d) and (n,nd) reaction, double differential measurements detecting the deuteron are recommended. Such measurements may also provide important additional data for modeling in the form of (n,xp) and (n,xt) double differential cross sections. Measurements with the 'activation-technique' would need to employ a combination of two reactions. Such measurements are complicated, since traces of natural vanadium are a major source of contamination and because the induced activity will be very low. Accelerator Mass Spectrometry is deemed not feasible on account of the background resulting from the wide spread use of vanadium in structural parts. In view of these difficulties it is unlikely that experimentally the cross section for the production of a specific isotope will be accessible. Modeling would have to be invoked.

Comments for achieved accuracy:
According to the attached report a single measurement at 14 MeV exists. Above that energy two recent evaluations divergence by nearly a factor 2.

Review comment:
Cr-52 has been under re-evaluation several times in the recent past. For this particular reaction it appears that no progress can be made without new experimental data. In view of the predicted trends in the cross section, it appears that the emphasis of new experimental work should be in the domain above 14 MeV. However, the energy range between threshold (8441 keV) and 14 MeV may be important in an actual fusion reactor.

Additional file attached: effdoc-1015.pdf