Krylovskii State Scientific Center

Saint Petersburg, Russia

Krylovskii State Scientific Center

Saint Petersburg, Russia
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Kuchin N.L.,Krylovskii State Scientific Center | Laikin A.I.,Krylovskii State Scientific Center | Platovskikh Y.A.,Krylovskii State Scientific Center
Atomic Energy | Year: 2014

A method is proposed for analyzing and evaluating the dynamics of self-decontamination of the region of the Fukushima-1 NPP contaminated by radioactive substances. The activity flux into the sea and average self-decontamination time of the territory due to decay and wash-off of the radionuclides 137Cs and 134Cs in the region of the NPP are obtained. The wash-off time constant of 137Cs for the contaminated territory is determined from the experimental data. It is significantly greater than for the basins of the other rivers studied. This is due to the hydrological particularities of the rivers in Japan. It is shown that the maximum dose rate in the region of contamination will decrease to the background level in approximately 200 years. It is determined that the 137Cs concentration in suspension does not depend on the water flow rate in the river; the 137Cs flux is proportional to this flow rate, including in floods. © 2014, Springer Science+Business Media New York.


Kuchin N.L.,Krylovskii State Scientific Center | Laikin A.I.,Krylovskii State Scientific Center | Platovskikh Yu.A.,Krylovskii State Scientific Center
Atomic Energy | Year: 2014

It is found that in the presence of several barriers the emanation of radionuclides from a sunken object always has a maximum as a function of time. Its position depends on the time constant of radionuclide emanation from the fuel elements and the transport time constants of the object's systems. After emanation, a radionuclide is carried away by currents and transported into the sediments by settling and diffusion. A relation between the processes occurring inside the object and the sediments is found. Measurements performed in the gulfs of Novaya Zemlya show that the radionuclide distribution over depth in the sediments has a maximum corresponding to the indicated emanation peak as a function of time. For the gulfs of Novaya Zemlya, the limits of these time constants are determined from the measurements. It is shown that the time constant of radionuclide emanation from fuel elements decreases with time. © 2014 Springer Science+Business Media New York.


Laikin A.I.,Krylovskii State Scientific Center | Platovskikh Y.A.,Krylovskii State Scientific Center
Atomic Energy | Year: 2015

To evaluate detection characteristics by means of an analysis of γ-ray spectra, it is necessary to set a probability distribution for the number of counts that contains their mathematical expectation. In measurements, the mathematical expectation is a random quantity. These random quantities are averaged for the Poisson and Gaussian distributions. Calculations of the detection characteristics show that for a small average number of counts 10–100 the averaged Poisson distribution should be used. The Gaussian approximation and the ordinary Poisson distribution lead to large errors in the detection characteristics. © 2015, Springer Science+Business Media New York.

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