Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident Initiated by SBLOCA in the APR1400 Containment

We performed a hydrogen combustion analysis in the Advanced Power Reactor 1400 MWe (APR1400) containment during a severe accident initiated by a small break loss of coolant accident (SBLOCA) which occurred at a lower part of the cold leg using a multi-dimensional hydrogen analysis system (MHAS) to confirm the integrity of the APR1400 containment. The MHAS was developed by combining MAAP, GASFLOW, and COM3D to simulate hydrogen release, distribution and combustion in the containment of a nuclear power plant during the severe accidents in the containment of a nuclear power reactor. The calculated peak pressure due to the flame acceleration by the COM3D, using the GASFLOW results as an initial condition of the hydrogen distribution, was approximately 555 kPa, which is lower than the fracture pressure 1223 kPa of the APR1400 containment. To induce a higher peak pressure resulted from a strong flame acceleration in the containment, we intentionally assumed several things in developing an accident scenario of the SBLOCA. Therefore, we may judge that the integrity of the APR1400 containment can be maintained even though the hydrogen combustion occurs during the severe accident initiated by the SBLOCA.

Set-Based Models for Cryptocurrency Software

Formal methods (FM) are mathematics-based software development methods aimed at producing ``code for a nuclear power reactor''. That is, due application of FM can produce bug-free, zero-defect, correct-by-construction, guaranteed, certified software. However, the software industry seldom use FM. One of the main reasons for such a situation is that there exists the perception (which might well be a fact) that FM increase software costs. On the other hand, FM can be partially applied thus producing high-quality software, although not necessarily bug-free. In this paper we outline some FM related techniques whose application the cryptocurrency community should take into consideration because they could bridge the gap between ``loose web code'' and ``code for a nuclear power reactor''. We include relevant case studies in the area of cryptocurrency.

Study of Parametric Interactions in the Nuclear Reactor Control with Feedback

This article considers the principal theoretical possibility of regulating a nuclear power reactor under changing operating modes conditions when external periodic disturbances take place in conditions of changing the operating mode. By the external periodic perturbation a downward change in the conditions of the heat sink was meant. The magnitude of the changes was preliminarily calculated in such a way that the operating conditions of the power plant did not exceed the boundaries of the safe operation zone of the reactor. In the case of approaching the operation parameters to the critical ones, the heat sink was increased until the working conditions returned to their previous state. In this work the amplitude frequency response of a non-linearly enhanced system in the nuclear power plant operating conditions when non-linearly reacting to external periodic influences has been studied. The external cyclic disturbances effect produced on the reactor that initially existed under stationary operating conditions has been considered. The research was carried out by numerical simulation of the competition between processes occurring in a nuclear power plant and determined by the system’s reaction time and relaxation time while responding to periodic external influences. Calculations of the relaxation time dependence on the fixed frequency-revealing external influence’s temperature are presented. Also, the relaxation time dependence on the frequency of external influence at a fixed temperature for systems with various relaxation periods was calculated. It is determined that when the dependence between system temperature and the external influence time is calculated, there exists a wide range of possible frequency control. To evaluate the behavior of a nuclear power reactor under conditions of operating modes changes, a fundamental physical mathematical model of the reactor’s state under external harmonic influence is presented. It is based on the nonlinear Riccati equation. The external harmonic effect was simulated by changing the heat supply and heat removal conditions near the critical point.

The Effects of U-233 Impurity on U-232 and Tl-208 Buildup in Experimental Power Reactor with Thorium-Based Fuel

The existence of Tl-208 in thorium fuel cycle is a double-edged sword. Tl-208 is a high-energy 2.6 MeV gamma emitter, which acts as an effective proliferation barrier while simultaneously complicating the handling of the spent fuel. To ensure the safety of the latter, the buildup of both Tl-208 and its parent, U-232, are necessary to be understood. This paper attempts to analyse the buildup of U-232 and Tl-208 in the Reaktor Daya Eksperimental (Experimental Power Reactor/RDE) fuel based on thorium cycle, using various U-233 isotopic vectors. The simulation result shows that U-232-contaminated fresh fuels ended up with higher Tl-208 and U-232 activities at the end of cycle (EOC) compared with uncontaminated fresh fuel. However, their U-232 build-up rate are lower and even negative at one case. Then, lower U-233 purity caused a higher U-232 and Tl-208 activities at EOC. This result implies a considerable difference of isotope buildup between the various U-233 vectors. Consequently, the thorium cycle-based RDE spent fuel handling should consider the isotopic vector of U-233 used in fresh fuel.

Influence of Semi Die Angle on the Forming Process of Ribbed Tube

Cladding tube is one of the key components in nuclear power reactor. In this paper, the forming process of a new cladding tube is investigated, namely ribbed tube. The influence of semi die angle on the forming process of ribbed tube is studied. Firstly, the strain-stress curves of 316L stainless steel (SS) at different strain rates are obtained. Based on the strain-stress curves, a modified Johnson-Cook constitutive model which ignore the influence of temperature are used, and the parameters of the modified model are determined. Then, the modified Johnson-Cook is used to establish the finite element (FE) model of ribbed tube drawing process, and two pass drawing process is adopted in this paper. Finally, the influence of semi die angle on the forming process (forming quality and drawing force) of ribbed tube is elucidated, and the credibility of the simulation is confirmed by comparing the simulation and experimental results. The results show that when the semi die angle less than 8 °, all the formed ribbed tubes meet the requirement, but there are inner grooves appear at the inner wall, and the inner grooves cannot be avoided in the drawing process. Moreover, when the semi die angle is 8 °, the inner grooves have smallest depth.

Shear Wave Velocity (Vs) at Reactor Building, Experimental Power Reactor Indonesia

Experimental Power Reactor (RDE) is a Gen IV Reactor type with Hydrogen Gas Cooler. Despite this type of reactor has high safety performance, earthquake hazard should be demonstrated. Detail Engineering Design Activity on RDE has been conducted in the past 3 years. In the end of this phase, preliminary parameter design such as shear wave velocity (Vs) should be defined. This parameter correlated with subsurface condition which has high uncertainty. This study is conducted in order to estimate values of Vs. Generally, the data collection is carried out through geotechnical investigation but this method cost more time and resources. In the recent decades, another method has been widely introduced which is geophysical passive source Microtremor Array Measurement (MAM) with Spatial Auto Correlation (SPAC) method. This method can be used to estimate values of Vs and can be used as preliminary reference to define the position of borehole before construction phase getting started. The result shows, the location of reactor building is estimated to have 5 soil layers with varying Vs value. The Vs value of the first soil layer is about 152 m/s started from the surface to 8 m depth. The second soil layer has 169 m/s Vs value started from 8 m to 20 m depth. The third soil layer, started from 20 m to 36 m depth, has 384 m/s Vs value. The next layer as the fourth layer of soil, started from 36 m to 70 m depth with a value of Vs around 526 m/s. The last soil layer with a depth 70 m to 100 m, has Vs value of 667 m/s. Based on these Vs value estimation from surface to 30 m depth, the average value of the shear wave velocity (Vs 30) is m/s. Thus, reactor building is located in the site class SD with medium soil categories according to SNI 1726-2012. The foundation design and excavation planning phase, this information is needed.

Management of Site Evaluation: A Lesson Learnt of 10 MW HTGR Experimental Power Reactor (RDE) Project Site Licensing

In 2013, a pre-project activity of Experimental Power Reactor (RDE Project) was started. The reactor type is a High Temperature Gas-cooled Reactor (HTGR) with a 10 MWth capacity. At present the project has been postponed due to some reason, however, there was an important stage that has been achieved, regarding the site evaluation process to obtain site permits from the Regulatory Body (BAPETEN). Site evaluation is an critical activity that will guarantee the safety of nuclear facilities from natural and human induced external events as well as the safety of population and the environment due to nuclear facility accidents. Site evaluation for the RDE project has the same process as a large NPP project, considering that at the time of the site evaluation process there were no specific regulations that considered a graded approach for a mini-scale NPP. The site evaluation process includes two stages, namely 1). Site Evaluation Program (SEP) and Management System of Site Evaluation (MSSE) Approval and 2) Site Evaluation Approval. SEP is intended to establish the scope and criteria for site evaluation safety. Whereas the Site Evaluation Management System is a managerial instrument that makes site safety as the top priority in each activity and process of RDE site evaluation. BATAN as the project owner delivered the SEP document and MSSE to BAPETEN on March 10, 2014. These documents was intensively discussed by BAPETEN and BATAN to determine agreement on the scope of site evaluation, criteria and management aspects based on site safety considerations. The technical aspects that must be evaluated are seismicity, volcanic hazard, geotechnical and foundation, meteorology, hydrology, human induced events, dispersion and population distribution. This document was approved by BAPETEN on March 2, 2015. Considering the very wide scope with various fields of competence and need supporting data for evaluation, this can not be done only by BATAN experts, it must collaborate with various institution that have competence related to the site aspect. The experts that involved in the site evaluation come from Meteorology and Geophysics Agency (BMKG) for seismic and meteorological aspects, Geospatial Information Agency (BIG) to support geospatial data and ground movements/deformation, Geological Survey Center (PSG) to support geological data and geological structures, Center for Volcanology and Geological Disaster Mitigation (PVMBG) to support volcanic catalog data and volcanic hazard, University to support geotechnical, foundation and hydrology evaluation. BATAN experts from various Centers involved for evaluating topography, human induced events, dispersion, dose assessment, population distribution, emergency preparedness, and technology aspects. Data acquisition activities such as geophysics, drilling, geological mapping, volcanic mapping, hydrology, satellite imagery and digitizing processes are contracted through third parties with guidance developed by the BATAN Expert Team. Considering the very limited time and financial resources availability, in order to achieve the effectiveness of all activities, a special organization was formed to control site evaluation with the BATAN Chairman as Top Management. The Site evaluation document was submitted in two stages. The first stage is administrative completeness and it was declared administratively complete on November 15, 2015. The second step is BAPETEN assessed and evaluated the technical documents submitted to determine the acceptability of the site. The process of evaluating the site evaluation document lasts quite a long and intensive. Finally, the site permit was issued on January 23, 2017. The valuable lessons during the site evaluation project are: 1) It require the same understanding and perception between applicant and regulator regarding the site licensing process; 2) The establishment and implementation of an effective organization; 3) controlling the project schedule.