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The operational lifespan of all four units at the Hungarian Paks Nuclear Power Plant (NPP) has been extended by 20 years beyond the original 30-year term. This extension has been implemented gradually, in one- to two-year increments, since 2013. The Hungarian Atomic Energy Authority, responsible for granting approval for these life extensions, has prescribed the continuous and rigorous monitoring of the reactor pressure vessel (RPV) throughout the plant’s extended service life. Among the key requirements is the validation of the neutron transport calculations, with specific attention to the large Lead Factor (LF), which reaches around 12 at the reactor core’s center. To meet these regulatory requirements, neutron transport calculations and reactor dosimetry measurements using neutron activation detectors (neutron monitors) have been conducted both inside and outside the RPV. Inside measurements were taken in the RPV surveillance channel, while outside measurements were conducted in the cavity adjacent to the outer wall of the RPV. These efforts aim to determine the key parameters of the neutron irradiation and validation is achieved if the experimental results agree with the neutron transport calculations at both the surveillance position and the RPV's outer wall (in the cavity), ensuring that the calculations are also valid for the inner wall of the RPV. This paper presents the validation of experimental data used to confirm the accuracy of the neutron transport calculations. The results of irradiations conducted over one- and four-year periods are compared and analyzed to demonstrate the authenticity of the experimental data for validation of the calculation results.

The phenomenon of laser-assisted alpha decay is studied within the framework of non-Hermitian quantum theory integrated with the (t, t ′)-formalism. The width and the lifetime of the alpha cluster of a specific isotope is extracted from the spectrum of the complex-scaled Hamiltonian operator of the nuclear system and estimated numerically. The laser-field-induced correction to the lifetime is computed by first-order (t, t ′)-perturbation calculation with regard to different polarization states and control parameters of the external laser field, adjusting appropriate intensity and photon energy pairs by examining the limit of the non-relativistic approximation of the problem. [ABSTRACT FROM AUTHOR]

The energy in nuclear power plants is produced by thermal fission. It is extremely important to be able to monitor the processes in the reactor to ensure the safety and reliability of the power plant. One of the main traits of the reactor core is neutron flux. It changes in time and space therefore it is crucial to be able to simulate its changes with computer codes. In the research work a program code was established in the Matlab software with which the neutron flux of a one-dimensional zone can be simulated with homogenous and heterogenic zone parameters as well. The code is written using the one-group one-dimensional time- and space-dependent diffusion equation. The equation of an average delayed neutron group and xenon and iodine distributions was also included in the system to give a more precise look on the problem. The main innovation in the code is that numerical methods were used to solve the problem: the finite difference approach was applied for the place-dependent and for the time-dependent solution. The advantage of this code compared to other ones is that one-dimensional zones can be simulated in a really short time and it still gives a precise solution because of the complex numerical methods used. [ABSTRACT FROM AUTHOR]

Following an initial Round Robin inter-comparison of gamma spectrometry measurements reported in 2014, this paper presents results from the first part of a second Round Robin inter-comparison commissioned by the European Working Group on Reactor Dosimetry in 2018. Measurements were performed by thirteen European organisations on a set of irradiated neutron activation detectors representative of those commonly used by the Reactor Dosimetry community to measure neutron fluence using gamma spectrometry methods. The radionuclides measured were 110mAg, 58Co, 60Co, 54Mn, and 46Sc. The purpose of the exercise was to demonstrate the level of consistency between participating organisations in blind tests of measurements. The samples used were disks of iron, nickel, titanium, and two standard alloys of aluminium, one of 1% cobalt and the other 1% silver. They were irradiated in the MARIA reactor operated by National Centre for Nuclear Research, Poland. Participants provided their results to an independent referee who collated and compared the data. The results are presented in an anonymised form together with discussion and conclusions which may be drawn from the exercise. Good agreement was obtained with standard deviations for individual measurements between 2.0% (54Mn) and 5.6% (60Co). Overall, the results obtained from the latter Round Robin show less consistency than those from the first Round Robin, which is attributed to the participation of a wider pool of organisations.