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International Reactor Dosimetry File 2002 - IAEA Publications

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— 241 Am(n,f): No up to date experimental data are available for this<br />

reaction, therefore the corresponding C/E values could not be<br />

derived.<br />

3.3. CONCLUSIONS<br />

Based on the results of the cross-section selection procedure outlined<br />

above, the following principal conclusions can be drawn related to the data in<br />

Tables 3.3 and 3.4:<br />

(a) Very few new cross-section evaluations accompanied by complete<br />

uncertainty information have been undertaken in the low neutron energy<br />

region over the previous decade, except the 139 La(n,γ) 140 La and<br />

186 W(n,γ) 187 W reactions evaluated for the RRDF [3.4].<br />

(b) Integral values of the selected cross-sections in the thermal neutron<br />

region exhibit very good agreement in most cases with the corresponding<br />

recommended experimental values.<br />

(c) Resonance integrals of the<br />

55 Mn(n,γ) 56 Mn,<br />

58 Fe(n,γ) 59 Fe and<br />

93 Nb(n,γ) 94 Nb reactions deviate significantly (>10%) from the corresponding<br />

experimental data. Further investigation (e.g. testing the data in<br />

benchmark neutron fields) and new cross-section evaluations are<br />

required.<br />

(d) For the 23 Na(n,γ) 24 Na, 93 Nb(n,γ) 94 Nb, 115 In(n,γ) 116 In m and 181 Ta(n,γ) 182 Ta<br />

reactions and the 232 Th(n,γ) 233 Th reaction below 15 eV, the uncertainty<br />

information is quantified in terms of diagonal covariance matrices only.<br />

New evaluations with complete covariance information are required.<br />

(e) Unreliable uncertainty data are present in all the investigated crosssection<br />

libraries for the 197 Au(n,γ) 198 Au and 235 U(n,f) reactions<br />

(withdrawn from ENDF/B-VI). New cross-section evaluations with<br />

complete covariance information are required.<br />

(f) Selected cross-sections in Table 3.3 should be subjected to a consistency<br />

test by comparing the relevant integral data with the corresponding<br />

experimental values in benchmark neutron fields.<br />

24

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