Measurements of the neutron spectrum energy in the IPEN/MB-01 reactor core

Abstract

This work presents the results of neutron spectrum measurements at central position of the IPEN/MB-01 reactor core. For this purpose has been used several activation foils (Au, Sc, U, Mg, Ti, Ni, and In Foils) that have been irradiated at central position of the reactor core (standard rectangular configuration 28 × 26 fuel rods) in the maximum power level (100 watts). After this one the foils were counting at HPGe solid state detector (gamma spectrometry). The nuclear reaction rates experimental results (saturated activity per target nucleus) is together with an initial approach to the neutron reactor spectrum (estimated by reactor physics cellular codes) the main data to obtain the most appropriated neutron spectrum at the irradiation position by interactive adjustment process using the unfolding SANDBP code. The results obtained were (5.1312±0.1609).10 9 n/cm 2 .s to the integral neutron flux, (9.8087±0.4974).10 8 n/cm 2 to the thermal neutron flux, (3.2272 ± 0.4378).10 9 n/cm 2 .s to the intermediate neutron flux and (1.9040 ± 0.6390).10 9 n/cm 2 .s to the fast neutron flux. These results are important and may be used to check and validate reactor physics codes and several nuclear data libraries.

Deterministic evaluation of safety parameters and neutron flux spectra in the MNSR research reactor using DRAGON-4 code

“…Where that E the neutron energy and E 0 is chosen to be the maximum energy that the neutron can achieve. The neutron flux spectrum per unit lethargy for every energy group has been calculated by multiplying the neutron energy flux spectrum for every energy group by the average energy of each energy group (Bitelli, Martins, & Jerez, 2009).…”

Using the Bayes’ theorem of conditional probabilities to obtain the neutron flux of the RECH-1 experimental nuclear reactor at CCHEN

“…Obtaining neutron fluxes from neutron activation measurements is a standard procedure. Similar reactors worldwide [1][2][3] have used it in addition to iterative unfolding algorithms. Those algorithms need an initial input flux to start the iteration.…”

Determinação experimental de razões espectrais e do espectro de energia dos nêutrons no combustível do reator nuclear IPEN/MB-01

“…A distribuição energética dos nêutrons no reator, tal qual a distribuição espacial em grupos de energia térmico, intermediário ou rápido, é de fundamental importância, pois, do seu conhecimento pode-se aferir com razoável exatidão uma série de parâmetros neutrônicos, como: taxas de reação nuclear, tempo útil do combustível e, parâmetros de segurança, como: distribuição de temperatura e reatividade, sendo, portanto muito útil nas áreas de Física, Engenharia, projeto, segurança e operação de centrais nucleares [1,2] .…”

“…197 Au Inferior 1,82x10 5 4,58x10 2 2,02x10 -13 7,20x10 -16 0,36% 197 Au Superior 1,81x10 5 5,52x10 2 2,02x10 -13 8,24x10 -16 0,40% 197 Au* Inferior 1,26x10 5 5,14x10 3 1,41x10 -13 5,72x10 -15 4,06% 197 Au* Superior 1,29x10 5 4,84x10 3 1,44x10 -13 5,42x10 - 15 3,76% 238 U Inferior 2,17x10 6 1,20x10 5 6,16x10 -15 3,42x10 - 16 5,54% 238 U Superior 2,19x10 6 1,35x10 5 Ni Superior 1,01x10 5 4,52x10 3 1,18x10 -16 5,28x10 -18 4,48% 24 Mg Superior 6,18x10 2…”

“…Todos os espectros foram obtidos da mesma forma, através do código MCNP-4C, utilizando o cartão "fmesh4" para 1x10 6 ciclos em um total de 2x10 9 Segundo Zjolnay [39] é desejável realizar-se no máximo 3 iterações, pois acima disso o processo de ajuste passa a ser um procedimento puramente matemático, perdendo-se a informação da física do problema, fornecida pelos resultados experimentais, obtidos quando da irradiação dos detectores de ativação. 4,0383x10 9 1,5820x10 7 0,39 <0,2x10 -6 4,6284x10 8 2,7600x10 6 0,60 <0,56x10 -6 6,1940x10 8 2,9800x10 6 0,48 >0, 1 1,9523x10 9 7,5320x10 6 0,39 >0, 4 1,5964x10 9 8,7060x10 6 0,54 >0, 5 1,5202x10 9 8,9820x10 6 0,59 >1,0 1,0783x10 9 1,0702x10 7 0,99 [27] .…”