Monte Carlo verification of the holder correction factors for the radiophotoluminescent glass dosimeter used by the IAEA in international dosimetry audits

The International Atomic Energy Agency (IAEA), jointly with the World Health Organization (WHO), has operated a postal dosimetry audit program for radiotherapy centers worldwide since 1969. In 2017 the IAEA introduced a new methodology based on radiophotoluminescent dosimetry (RPLD) for these audits. The detection system consists of a phosphate glass dosimeter inserted in a plastic capsule that is kept in measuring position with a PMMA holder during irradiation. Correction factors for this holder were obtained using experimental methods. In this work these methods are described and the resulting factors are verified by means of Monte Carlo simulation with the general-purpose code PENELOPE for a range of photon beam qualities relevant in radiotherapy. The study relies on a detailed geometrical representation of the experimental setup. Various photon beams were obtained from faithful modeling of the corresponding linacs. Monte Carlo simulation transport parameters are selected to ensure subpercent accuracy. The simulated correction factors fall in the interval 1.005–1.008 (±0.2%), with deviations with respect to experimental values not larger than 0.2(2)%. This study corroborates the validity of the holder correction factors currently used for the IAEA audits.Peer ReviewedPostprint (author's final draft

Behaviour of single-crystal nickel alloy in the conditions of high-temperature hydrogen corrosion

This study presents the results of the investigation of the behaviour of ZhS32-VI single-crystal nickel alloy in hydrogen environment or argon atmosphere at 850°C. The microstructure and chemical composition of corrosion deposits were studied by scanning electron microscopy and X-ray energy-dispersive analysis. It has been established that in argon containing an admixture of oxygen a dense scale rich in cobalt and nickel oxides is formed. At atmosphere containing 65% hydrogen and 35% argon an increased content of aluminum in the surface composition was noted. The influence of 100% hydrogen leads to segregation of tungsten and rhenium with the formation of convex growths. The data of simultaneous thermal analysis revealed that the amount of desorbed hydrogen can be from 0.08 to 0.14%

The turbulent dynamo as an instability in a noisy medium

We study an example of instability in presence of a multiplicative noise, namely the spontaneous generation of a magnetic field in a turbulent medium. This so-called turbulent dynamo problem remains challenging, experimentally and theoretically. In this field, the prevailing theory is the Mean-Field Dynamo (Krause and R\"{a}dler, 1980) where the dynamo effect is monitored by the mean magnetic field (other possible choices would be the energy, flux,...). In recent years, it has been shown on stochastic oscillators that this type of approach could be misleading. In this paper, we develop a stochastic description of the turbulent dynamo effect which permits us to define unambiguously a threshold for the dynamo effect, namely by globally analyzing the probability density function of the magnetic field instead of a given moment.Comment: 6 page

NUCLEAR FUEL FOR REACTOR WITH MOLTEN ACTIVE ZONE

FIELD: power industry. SUBSTANCE: nuclear fuel for reactor with molten active zone represents disperse mixture of isomorphic nitrides of uranium saturated as to isotope-235 with zirconium nitride, which is suspended in liquid lead. EFFECT: invention allows creating steady-state nuclear fuel and preventing layering of fuel system. 3 cl.Изобретение предложено для создания последующих поколений энергетических ядерных реакторов с активной зоной из расплавленных сред. Ядерное топливо для реактора с расплавленной активной зоной представляет собой дисперсную смесь изоморфных нитридов обогощенного по изотопу-235 урана с нитридом циркония, взвешенную в жидком свинце. Изобретение позволяет создать устойчивое ядерное топливо и предотвратить расслоение топливной системы. 2 з.п. ф-лы

Adding agility to Enterprise Process and Data Engineering

Managing development of large and complex enterprise architectures is a key problem in enterprise engineering. Nowadays one of the breathtaking topics considering enterprise context is real-time system agility. The paper discusses an appropriate general architecture pattern and provides insights how dynamic process management environment could be made. We survey general enterprise software architecture and current agility problems. We introduce a special component called a process knowledge base and justify its crucial role in achieving agility within the enterprise. We study both the architecture of the process knowledge base as well as formal basis for its implementation which relies upon the type theory

Behaviour of single-crystal nickel alloy in the conditions of high-temperature hydrogen corrosion

This study presents the results of the investigation of the behaviour of ZhS32-VI single-crystal nickel alloy in hydrogen environment or argon atmosphere at 850°C. The microstructure and chemical composition of corrosion deposits were studied by scanning electron microscopy and X-ray energy-dispersive analysis. It has been established that in argon containing an admixture of oxygen a dense scale rich in cobalt and nickel oxides is formed. At atmosphere containing 65% hydrogen and 35% argon an increased content of aluminum in the surface composition was noted. The influence of 100% hydrogen leads to segregation of tungsten and rhenium with the formation of convex growths. The data of simultaneous thermal analysis revealed that the amount of desorbed hydrogen can be from 0.08 to 0.14%