24-Cr-52(n,xd),(n,xt)

Dr Robin A. FORREST at UKAEA/CUL, UK

JEFF, EFF

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

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.

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).

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.

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.

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

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.

Completed (as of SG-C review of May 2018) - This request didn't trigger any measurement and should its priority rise again it will have to be resubmitted. Nevertheless, it has been partially addressed by the JEFF-3.2 evaluation using state-of-the-art nuclear reaction codes [Pereslavtsev:2011].

Please report any missing information to hprlinfo@oecd-nea.org

Theory/Evaluation

• P. Pereslavtsev et al., Evaluation of 50Cr, 52Cr, 53Cr, 54Cr Neutron Cross Section Data for Energies up to 200 MeV, Journal of the Korean Physical Society 59 (2011) 931