Neutrino method remote measurement of reactor power and power output

Abstract

The question of using neutrino radiation from reactors was first posed in the mid-1970s [1, 2]. The first demonstration measurements were performed when the neutrino laboratory was set up at the Rovno nuclear power plant and it was shown, for a small statistical sample, that neutrino radiation can, in principle, be used in practice [3, 4].The inadequacy of the statistics and the high background of extraneous radiation have always been the main obstacle to recording reactor antineutrinos (~e)' The apparatus presented in the present paper -the Rovno neutrino spectrometer [5] -has partially solved these problems. Installed in the neutrino laboratory, it is intended for solving both fundamental and applied problems. In the present paper it is presented as an apparatus for measuring the power output of a reactor and the fuel burnup from the total recorded flux and spectrum of antineutrinos.The neutrino flux is directly proportional to the reactor power with constant fuel composition. The fuel composition changes during reactor operation, and as a result the proportionality coefficient decreases by 5-7%. Until recently these changes were calculated theoretically. In the present work we observed experimentally the decrease, associated with uranium burnup and plutonium accumulation in the fuel core of the reactor, of the neutrino flux and we have measured for the first time the distortion of the antineutrino spectrum as a result of this effect.Thus this work is self-consistent. All necessary corrections can be extracted directly from the measurements and are not introduced by a computational method.Neutrino Detector and Recording of Neutrinos. The detector consists of a rectangular tank, made of transparent plexiglass and filled with a hydrogen-containing scintillator (1050 liters) containing gadolinium. The volume of the detector is viewed, through transparent lightguides, on both sides, with 84 FI~U-125 photomultipliers.Antineutrinos are recorded by the inverse/3-decay reaction on hydrogen nuclei ~e+p-*e++ nby detecting the positron together with the annihilation 3'-rays (first event), and then the neutron (second event) after it is moderated and captured by gadolinium. The detector is divided into two parts by light-reflecting surfaces. The measurements were conducted in the central volume (510 liters), and the annular volume of 540 liters was used to increase the detection efficiency of the annihilation 3' rays and the 3' rays from capture of neutrons by the gadolinium and as shielding from extraneous radiation.The apparatus described above is installed under the VVI~R-440 reactor, 18 m from its fuel core in a shielding steel housing.The measurements were performed in the same manner for a period of three years: 3-4 months before the reactor was shut down for planned preventive maintenance and partial reloading of fuel, one month of measurements of the correlated background during the maintenance, and once again 3-4 months of power measurements after maintenance. The background of random events, imitating the reactio...

Angra dos Reis reactor neutrino oscillation experiment

“…where N H is the number of hydrogen atoms in the fiducial volume, R is the distance from the source to the detection point and γ is a constant which takes into account the contributions to the power output made by the fissile isotopes 235 U, 238 U, 239 Pu and 241 Pu [16]. Recent studies have shown the feasibility of using the antineutrino emission from nuclear reactors as an on-line monitor of the reactor activity.…”

“…Recent studies have shown the feasibility of using the antineutrino emission from nuclear reactors as an on-line monitor of the reactor activity. A prototype of this kind of detector is running at the San Onofre reactor (U.S.A.) [17], and a previous experiment was done at the Rovno reactor (Ukraine) [16].…”

Calibração da potência do reator IPEN/MB-01 na configuração cilíndrica de menor excesso de reatividade obtida a partir da medida absoluta do fluxo médio de nêutrons

“…Ainda se considera que a medição do fluxo de neutrinos forneça um espectro da produção de plutônio no núcleo [4].…”

“…No processo de calibração, faz-se necessário se conhecer alguns parâmetros, o que pode ser feito pela espectrometria gama de alguns elementos químicos irradiados no núcleo de um reator de pesquisa [4]. Este é o caso dos detectores de ativação como as folhas de ouro …”

“…Esses fatores dependem da seção de choque, da geometria e da espessura do detector de ativação. A perturbação causada por um detector (folha) de ativação pode ser desprezada quando temos que [21], [4,7].…”