21-25 June 2021
Clarion Congress Hotel Prague
Europe/Prague timezone
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Measuring of cross-sections of minor isotopes of oxygen by water activation

Not scheduled
3rd floor (Clarion Congress Hotel Prague)

3rd floor

Clarion Congress Hotel Prague

Freyova 945/33, 190 00 Prague 9 - Vysočany
Oral presentation 04 Research Reactors and Particle Accelerators


Mr KOTNIK, Domen (Jožef Stefan Institute)


Water is typically used as a primary coolant in a majority of today’s fission reactors and will be used for cooling of the blanket in ITER and is also the main candidate as a coolant for future fusion reactors. Due to interactions with neutrons, which are generated during fission/fusion reactions, the water, more specifically hydrogen and oxygen isotopes, get activated. Relevant interactions occur on oxygen isotopes, e.g. $^{16 }$O(n,p)$^{16 }$N, $^{17 }$O(n,p)$^{17 }$N and $^{18 }$O(n,γ)$^{19 }$O, which further lead to the decay and emission of gamma rays or neutrons. As the cooling water loop extends outside of the primary biological shield additional protection for detectors, instrumentation and personnel have to be considered. This issue is even more relevant for fusion reactors as the dose rates due to the activated water will be approx. 5 orders of magnitude higher than in fission reactors.
To perform accurate and reliable simulations of dose fields due to the decay of activated water, it is extremely important to have reliable cross-section libraries for above-mentioned neutron interactions on oxygen isotopes. Currently, cross-sections for $^{16 }$O and $^{17 }$O are relatively well known, whereby the cross-section for $^{18 }$O is impoverished due to the lack of measurements and inconsistent evaluation data especially at the fast region and partially at the epithermal region.
The main focus of this paper will be studying of the oxygen cross-section by water activation on the research reactor TRIGA in Slovenia. Specifically, to find the degree of accuracy, which can be obtained by such an experiment by measuring characteristic gamma rays. Therefore, a sensitivity analysis will be performed by uncertainty propagation of relevant parameters, e.g. irradiation time, water measurement volume, pipe flow, etc. As the uncertainties for $^{18 }$O cross-section are expected to be largest, due to the complexity of measurements, e.g. low natural abundance of $^{18 }$O and lower integral cross-section, additional techniques will be used to obtain the integral value of cross-section at higher energies by using boron or cadmium filters and absolute calibration by directly comparing reaction rates.

Primary author

Mr KOTNIK, Domen (Jožef Stefan Institute)


Mr ŽOHAR, Andrej (Jožef Stefan Institute) Mr LENGAR, Igor (Jožef Stefan Institute) Mr TRKOV, Andrej (Jožef Stefan Institute) Mr SNOJ, Luka (Jožef Stefan Institute)

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