Detector Locations Research Articles

Study on UV optical field distribution of partial discharge in GIS disconnector based on ray tracing method

Abstract In order to clarify the distribution law of the radiation optical field of the gas insulated switchgear disconnector defect and determine the detection range of partial discharge optical sensor, the optical model of the gas insulated switchgear disconnector based on the uniform geometrical theory of diffraction theory is established based on ray tracing method, and the distribution of the radiation light field is calculated when partial discharge occurs at the key positions such as the basin insulator, shield, and support insulator barrel. Based on the maximum irradiance, average irradiance and attenuation characteristics on the shell interface, the distribution law is further analysed, and based on this, the optimal location of the ultraviolet detector is proposed.

FitFun: A modelling framework for successfully capturing the functional form and noise of observed traffic flow–density–speed relationships

Measurements of the average properties of vehicular traffic are inherently noisy. The distributions of flow and speed measurements at any particular density are non-Gaussian with density-dependent variance, skewness, and kurtosis. Previous studies have failed to properly account for these complicated noise properties. In remediation, we present FitFun, a general framework for modelling any observed flow–density–speed relationship. Models specified within FitFun incorporate components for both the functional form and the noise. We define three flexible noise model components and we fit 200 different models to a high-quality sample of 10,150 observed urban flow-occupancy relationships. We compare the fits using information criteria and assess fit quality through analysis of the residuals. We find that the non-parametric Sun model for the functional form component combined with a Skew Exponential Power Type III noise component significantly outperforms all of the other models. Interestingly, we find that the city, country, road topology, and detector location have virtually no impact on model performance and fit quality, which is very convenient for model selection. The only factor of relevance from those that we studied is the effective occupancy coverage of the data. We conclude that certain models specified judiciously within FitFun can successfully capture the functional form and noise of observed flow–density–speed relationships without the need to discard data taken during non-stationary conditions. This is particularly advantageous for urban data where stationary traffic conditions are rarely observed.

Safe Design of a Hydrogen-Powered Ship: CFD Simulation on Hydrogen Leakage in the Fuel Cell Room

Adopting proton exchange membrane fuel cells fuelled by hydrogen presents a promising solution for the shipping industry’s deep decarbonisation. However, the potential safety risks associated with hydrogen leakage pose a significant challenge to the development of hydrogen-powered ships. This study examines the safe design principles and leakage risks of the hydrogen gas supply system of China’s first newbuilt hydrogen-powered ship. This study utilises the computational fluid dynamics tool FLACS to analyse the hydrogen dispersion behaviour and concentration distributions in the hydrogen fuel cell room based on the ship’s parameters. This study predicts the flammable gas cloud and time points when gas monitoring points first reach the hydrogen volume concentrations of 0.8% and 1.6% in various leakage scenarios, including four different diameters (1, 3, 5, and 10 mm) and five different directions. This study’s findings indicate that smaller hydrogen pipeline diameters contribute to increased hydrogen safety. Specifically, in the hydrogen fuel cell room, a single-point leakage in a hydrogen pipeline with an inner diameter not exceeding 3 mm eliminates the possibility of flammable gas cloud explosions. Following a 10 mm leakage diameter, the hydrogen concentration in nearly all room positions reaches 4.0% within 6 s of leakage. While the leakage diameter does not impact the location of the monitoring point that first activates the hydrogen leak alarm and triggers an emergency hydrogen supply shutdown, the presence of obstructions near hydrogen detectors and the leakage direction can affect it. These insights provide guidance on the optimal locations for hydrogen detectors in the fuel cell room and the pipeline diameters on hydrogen gas supply systems, which can facilitate the safe design of hydrogen-powered ships.

Impact of the Frequency and Type of Procedures Performed in Nuclear Medicine Units on the Expected Radiological Hazard

Nuclear medicine procedures play an important role in medical diagnostics and therapy. They are related to the use of ionizing radiation, which affects the radiological exposure of all of the persons involved in their performance. The goal of the study was to estimate the doses associated with the performance of various nuclear medicine procedures in order to optimize workload management. The analysis was performed for 158 myocardial perfusion scintigraphy procedures, 24 bone scintigraphies, 9 thyroid scintigraphies (6 with use of 131I and 3 with 99mTc), 5 parathyroid glands and 5 renal scintigraphies. In this evaluation, two possible locations of thermoluminescent detectors, used for measurements, were taken into consideration: in the control room and directly next to the patient. It was shown how the radiological exposure varies depending on the performed procedure. For high activity procedures, ambient dose equivalent registered in the control room reached the level over 50% of allowed dose limit. For example, ambient dose equivalent obtained in control room when performing bone scintigraphy only was 1.13 ± 0.3 mSv. It is 68% of calculated dose limit in the examined time span. It has been shown that risk associated with nuclear medicine procedures is influenced not only by the type of procedure, but also by the frequency of their performance and compliance with the ALARA principle. Myocardial perfusion scintigraphy accounted for 79% of all evaluated procedures. The use of radiation shielding reduced the obtained doses from 14.7 ± 2.1 mSv in patient's vicinity to 1.47 ± 0.6 mSv behind the shielding. By comparing the results obtained for procedures and dose limits established by Polish Ministry of Health, it is possible to estimate what should be the optimal division of duties between staff, so that everyone receives similar doses.

Conceptual design of multichannel fast electron bremsstrahlung detection system to study fast electron dynamics during lower hybrid current drive in ADITYA-U tokamak

To drive plasma current non inductively, a Lower Hybrid Current Drive (LHCD) system with a passive-active multijunction (PAM) antenna for injecting lower hybrid wave (LHWs) has been designed, fabricated and to be integrated with ADITYA-U Tokamak. A fast electron population in the energy range of a few keV to several hundreds of keV is generated with the injection of the LHWs. These fast electrons interacting mainly with ions and electrons result in Hard X-Ray (HXR) emission called Fast Electron Bremsstrahlung acronym as FEB emission. A single channel FEB detection system is being used in the earlier experiment of LHCD in ADITYA-U tokamak. However, the single channel detection system can't provide a radial emissivity profile of HXR intensity distribution. In order to determine a radial emissivity profile, for the first time, a multichannel FEB detection system is designed for ADITYA-U tokamak. This paper describes the detailed conceptual design for the selection of suitable detectors, optimization of the collimators, shielding geometry, and low energy filtering cut-off. In the present design analysis, the soller collimator concept is considered over a simple pinhole camera system due to its several advantages. In order to optimize the multichannel FEB system parameters for the best possible performance, a forwarded modelling code has been used. The signal to background ratio at each detector location has been estimated for a few system parameters and reported herein.

E-RPT: Ecuadorian radioactive particle tracking. Proposal and evaluation of a low-budget RPT system with GEANT4

Radioactive Particle Tracking (RPT) is a non-invasive measurement technique used to reconstruct the Lagrangian particle field inside a fluid flow. This technique tracks the trajectories followed by radioactive particles that move along the fluid, and it is based on the counts registered by radiation detectors that are placed strategically around the boundaries of the system. The aim of this paper is to develop a low-budget RPT system proposed by the Departamento de Ciencias Nucleares of the Escuela Politécnica Nacional and to generate a GEANT4 model of it for optimizing its design. This system is based on the usage of the minimum amount of radiation detectors required to track a tracer and on the innovative idea of calibrating them with moving particles. To achieve this, energy and efficiency calibrations were performed with a single NaI detector, and their results were compared with the results generated with a GEANT4 model simulation. As a result of this comparison, another methodology was proposed to add the effects of the electronic detector chain in the simulated results by a Detection Correction Factor (DCF) without further C++ coding in GEANT4. Next, the NaI detector was calibrated for moving particles. For this purpose, a single NaI was used in different experiments to analyze the influence of particle velocity, data acquisition systems, and radiation detector position along the x-axis, y-axis, and z-axis. Finally, these experiments were simulated in GEANT4 to improve the digital models. Particle positions were reconstructed based on the generation of Trajectory Spectrum (TS) which gives a specific count rate for each particle position as it moves on the x-axis. The magnitude and shape of TS were compared with DCF corrected simulated data and experimental results. This comparison showed that the variation of detector position along the x-axis changed the shape of TS, while the variation of the location along the y-axis and z-axis reduced the sensitivity of the detector. The existence of an effective zone of the detector location was identified. At this zone, the TS shows high changes in the count rate for low changes of particle position. Based on the overhead of the TS, it was demonstrated that this RPT system must employ at least 3 detectors to have capabilities to predict particle positions.

Novel framework for determining TPS-calculated doses corresponding to detector locations using 3D camera in in vivo surface dosimetry

Purpose. To address the shortcomings of current procedures for evaluating the measured-to-planned dose agreement in in vivo dosimetry (IVD), this study aimed to develop an accurate and efficient novel framework to identify the detector location placed on a patient’s skin surface using a 3D camera and determine the planned dose at the same anatomical position corresponding to the detector location. Methods. Breast cancer treatment was simulated using an anthropomorphic adult female phantom (ATOM 702D; CIRS, Norfolk, VA, USA). An optically stimulated luminescent dosimeter was used for surface dose measurements (MyOSLchip, RadPro International GmbH, Germany) at six IVD points. Three-dimensional surface imaging (3DSI) of the phantom with the detector was performed in the treatment position using a 3D camera. The developed framework, iSMART, was designed to import 3DSI and treatment planning data for determining the position of the IVD detectors in the 3D treatment planning DICOM image. The clinical usefulness of iSMART was evaluated in terms of accuracy and efficiency, for comparison with the results obtained using cone-beam computed tomography (CBCT) image guidance. Results. The relative dose difference between the planned doses determined using iSMART and CBCT images displayed similar accuracies (within approximately ±2.0%) at all detector locations. The relative dose differences between the planned and measured doses at the six detector locations ranged from –4.8% to 3.1% for the CBCT images and –3.5% to 2.1% for iSMART. The total time required to read the planned doses at six detector locations averaged at 8.1 and 0.8 min for the CBCT images and iSMART, respectively. Conclusions. The proposed framework can improve the robustness of IVD analyses and aid in accurate and efficient evaluations of the measured-to-planned dose agreement.

Determination of neutron flux redistribution factors for a typical pressurized water reactor ex-core measurements using Monte Carlo technique

In a typical pressurized water reactor, neutron detectors located outside the reactor core monitor reactor power. In addition, they are also used to measure the reactivity of the control rods. A novel approach to calculate the ex-core neutron detector response in a typical pressurized water reactor using the Monte Carlo technique is presented. A detailed ex-core model of the Krško nuclear power plant was developed using the Monte Carlo neutron transport code MCNP. Due to the location of the ex-core neutron detectors, the hybrid code ADVANTG is used to generate variance reduction parameters to accelerte the convergence of the results outside the reactor core. To use ADVANTG, the fixed neutron source had to be reconstructed from the criticality core calculation. This paper presents the sensitivity analysis of the response of the ex-core detectors to the neutron data libraries used, the description of the fixed neutron source and the ADVANTG parameters. It was found that a pin-wise description of the neutron source for at least two rows of fuel assemblies at the core periphery is necessary for accurate results. Our results show the importance of a correct description of the prompt neutron spectra in the high energy region and the impact this has on the response of the ex-core detectors. The method in which the prompt neutron fission spectra for important fission nuclides are weighted by the calculated reaction rates has been shown to be the best approximation, with deviations from the reference calculation within statistical uncertainty. The effect of nuclear data libraries on the response of the ex-core detector was investigated, and the difference between the ENDF/B-VII.0 and the ENDF/B-VIII.0 nuclear data libraries was ∼11%. When the deficient evaluation of the 56Fe isotope included in the ENDF/B-VIII.0 nuclear data library was replaced by the improved evaluation from the IAEA INDEN project, the differences decreased to ∼3.7%. In addition, neutron flux redistributions due to control rod movement were investigated and flux redistribution factors were updated using Monte Carlo particle transport methods. The reaction rate redistribution factors obtained with methods presented in this paper are within 1% agreement with the currently used factors.

A Checkpointing Recovery Approach for Soft Errors Based on Detector Locations

Soft errors are transient errors caused by single-event effects (SEEs) resulting from a strike by high-energy particles acting on sensitive areas of integrated circuits. Soft errors frequently occur in the space environment, adversely affecting the reliability of aerospace-based computing. A recovery process is launched to recover the program when soft errors are detected. A periodic checkpointing recovery approach is widely utilized to prevent soft errors. However, this approach does not consider the detector locations, resulting in a large time overhead. This paper proposes a checkpointing recovery approach for soft errors based on detector locations called DLCKPT. DLCKPT reduces the time overhead by considering detector locations. The experimental results show that the percentage decrease in the time overhead between the DLCKPT and the periodic checkpointing recovery approach is 13.4%. The average recovery rate and average space overhead are 99.3% and 44.4% for the periodic checkpointing recovery approach and 99.4% and 34.6% for the DLCKPT. These results show that the DLCKPT and the periodic checkpointing recovery approach produce comparable results for the recovery rate. The DLCKPT has a lower time overhead and a slightly lower space overhead than the periodic checkpointing recovery approach, demonstrating its effectiveness.

Cosmic muon tomography at the Wylfa reactor site utilising an anti-neutrino detector

An anti-neutrino detector (a prototype of VIDARR) was deployed at the Wylfa Magnox nuclear power station between 2014 and 2016. It was comprised of extruded plastic scintillating bars measuring 4 cm by 1 cm by 152 cm and utilised wavelength shifting fibres (WLS) and Multi-Pixel Photon Counters (MPPCs) to detect and quantify radiation. During deployment, the detector recorded cosmic muon events in accidental coincidence along with the anti-neutrino events. The cosmic muons produced in the upper atmosphere had their paths obscured by the power plant buildings as the cosmic muons originated behind the buildings. Cosmic muons have a significantly higher probability to be attenuated and/or absorbed by denser objects and so one-sided muographic methods were utilised to image the reactor site buildings. In order to achieve clear building outlines a control data set was taken at the University of Liverpool from 2016 to 2018 which had minimal occlusion of the cosmic muon flux by dense objects. By taking the ratio of these two data sets and using GEANT4 simulations it is possible to perform a one-sided cosmic muon tomography analysis. This analysis can be used to discern specific buildings, building heights, and features at the Wylfa reactor site including the reactor core/reactor core shielding using cosmic-ray events equivalent to that which would be seen in ∼ 3 hours of normal operation. This result demonstrates the feasibility of using cosmic muon analysis to determine a segmented detector's location with respect to surrounding buildings, assisted by aerial photography or satellite imagery.

Foregroundness-Aware Task Disentanglement and Self-Paced Curriculum Learning for Domain Adaptive Object Detection.

Unsupervised domain adaptive object detection (UDA-OD) is a challenging problem since it needs to locate and recognize objects while maintaining the generalization ability across domains. Most existing UDA-OD methods directly integrate the adaptive modules into the detectors. This integration procedure can significantly sacrifice the detection performances, though it enhances the generalization ability. To solve this problem, we propose an effective framework, named foregroundness-aware task disentanglement and self-paced curriculum adaptation (FA-TDCA), to disentangle the UDA-OD task into four independent subtasks of source detector pretraining, classification adaptation, location adaptation, and target detector training. The disentanglement can transfer the knowledge effectively while maintaining the detection performance of our model. In addition, we propose a new metric, i.e., foregroundness, and use it to evaluate the confidence of the location result. We use both foregroundness and classification confidence to assess the label quality of the proposals. For effective knowledge transfer across domains, we utilize a self-paced curriculum learning paradigm to train adaptors and gradually improve the quality of the pseudolabels associated with the target samples. Experiment results indicate that our method achieves state-of-the-art results on four cross-domain object detection tasks.

Application of atmospheric dispersion modelling in finding optimal locations of early warning stations around a nuclear power plant

The paper investigates a practical problem of finding optimal locations of radiometric detectors for the automatic early warning measurements around nuclear facilities. The proposed methodology combines an analysis of the capabilities of different detectors with atmospheric dispersion modelling in the JRodos decision support system. It was found that the radioactive contamination after a small abnormal release might be impossible to detect for a less sensitive device (like a popular GM counter) further away than 5 km from the nuclear reactor. On the other hand, a more sensitive detector (like a 3” NaI scintillator) could be inappropriate for measurements within a shorter distance because the radiation field could be too high. This work was performed in the context of the planned first Polish nuclear power plant, but our approach and findings are general and apply to other facilities using a pressurised water reactor with electrical power of about 1 GW.

Reactor physics calculation and measurement during first approach to criticality of Apsara-U research reactor

Apsara-U is 2 MW swimming pool type research reactor with low enriched uranium fuelled core. On 10th September 2018, Apsara-U was made critical at 18:41 hrs. After the First Approach to Criticality (FAC) of Apsara-U, low power physics experiments were carried out. The experiments included reactivity worth measurement of all reactivity devices and measurement of the isothermal temperature coefficient of reactivity. Inflated reactivity worth of Shut off Rods as calculated from the power from some of the neutronic channels were obtained on account of shadowing effect of neutron reaching the detector locations. Further the isothermal coefficient of reactivity was observed positive. In this paper, we discuss the mentioned Reactor Physics measurement and related theoretical calculation during FAC that includes solving the benchmark problem for validating the calculation tools, and steady state thermal hydraulic analysis, Reactivity initiated transients for the FAC core configuration for ascertaining the safety of the reactor.

Design of a Fire Location Monitoring System Using Temperature and Smoke Detectors on Sea Ships

A fire location monitoring system is designed in this study to determine the location of a fire on a ship. The inputs used are temperature detectors and smoke detectors. The fire location monitoring system is designed using raspberry pi as a mini pc, temperature detector, smoke detector, alarm and Lazarus as a user interface. The room used as the object of research consists of the control room, steering room, engine room and kitchen room. The type and number of detectors used vary depending on the design of the detector placement in each room. Based on the tests that have been carried out, the fire location monitoring system is able to detect a fire when the temperature or smoke detector is active. In addition, the system is able to show the location of detectors that actively detect fires accompanied by an alarm sound. The average performance of the system in detecting a fire is 93%.

Impacts of Various Parameters on Transit Signal Priority Effectiveness

This research examines the impacts of a number of traffic parameters on the effectiveness of a Transit Signal Priority (TSP) application. TSP is tested with the 98 B-line rapid buses along Granville Street in the City of Vancouver as a case study. VISSIM, a micro-simulation software (PTV 2002), is used to simulate TSP operation on the corridor. The traffic parameters studied include: bus approach volume, cross street volume/capacity (v/c) ratio, bus headway, bus stop location, bus check-in detector location, left turn condition, and signal coordination. Based on results from these experiments, recommendations are provided for TSP application on Granville Street. In general, it is found that a TSP application would be most effective under a traffic condition that has moderate-to-heavy bus approach volume, little or no turning volume hindering bus movement, slight-to-moderate cross street v/c ratio, farside bus stop, and signal coordination for traffic running in the peak direction.

Coupling of Photonic Waveguides to Integrated Detectors Using 3D Inverse Tapering

We report on the design, fabrication, and characterization of a Silicon Nitride (SiN)-based integrated photonic chip in which the dielectric waveguides are coupled to photodetectors integrated homogeneously into the Silicon substrate. The photonic-electronic coupling was realized by a 3D inverse tapering of SiN waveguides. The novelty of our approach consists in tapering the waveguide in the vertical direction by means of an engineered wet chemical etching. This allows for a smooth transition from a full-height to an arbitrarily thin waveguide thickness at the detector location, expanding adiabatically the optical mode towards the latter. The measured chips showed a responsivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R\approx 109\;\mu$</tex-math></inline-formula> A/mW and a corresponding quantum efficiency of 16% at an excitation wavelength of 850 nm. Our technological solution offers a versatile method for a top-down monolithic integration of lightwave circuitries with substrate-located photon sensing devices.

Tests of a new code that simulates the evolution of solar winds and CMEs

We present the tests of a new code that solves Euler equations in three dimensions used to simulate the dynamics of the Solar Wind. The code is based on a finite volume discretization and uses high resolution shock capturing methods, with second order variable reconstructors and approximate flux formulae of the HLL class. It uses Cartesian coordinates and fixed mesh refinement. The equations are written in flux balance law form, which allows the evolution of conservative variables. The evolution is carried out using the method of lines with second order time integration. For the simulation of a solar wind we assume the Sun lies at the coordinate origin, and inject the fluid variables through the surface of a lego-sphere with radius 20R ⊙, where all the characteristic speeds point outwards from the solar surface. We manage to obtain stationary winds that reproduce winds of literature in terms of density, velocity and temperature of the plasma. On top of the stationary wind it is possible to launch Coronal Mass Ejections (CMEs) that propagate through the stationary Solar Wind from the injection surface all the way to the Earth. Finally, in order to incorporate the role of orbiting satellites that monitor Solar Winds and CMEs, the code also measures wind variables at detector locations on their actual trajectories around the Sun.

Operational optimization at signalized metering roundabouts using cuckoo search/local search algorithm

A metering roundabout where traffic is controlled by traffic lights with phase times influenced by queue detector occupancy might be the solution to enhance performance when there are unbalanced traffic flows at roundabouts. There have, however, been minimal studies on how the distance of the queue detector from the stop line affects signal phase time durations and the queuing lengths. This research, therefore, seeks to develop a Cuckoo Search/Local search Algorithm using parameters such as arrival volumes, conflicting volumes, detector distance and phase time to investigate the relationship of signal setting, detector location and queuing formulations. Also, some additional statistical tests were performed for the fitness of the data. In order to conduct solid model calibrations and validations, model output data was compared against the AIMSUN model. The results from the analyses demonstrated that the queue detector distance can affect phase time durations and vehicle queuing lengths on the controlling approach as well as queuing lengths on the metered approach. This study showed that, based on the study for the Old Belair Road roundabout, the total queue length (controlling + metered) will be minimized from 689 to 499 m by the proposed methods when the detector is relocated at 210 m from the roundabout stop line, giving longer phase green times and resulting in decreased intersection queuing lengths.

Experimental study on smoke flow behaviour under ships’ deck structures in early stages of fire

In ships’ cargo spaces carrying vehicles, so called “vehicle spaces”, fire has sometimes taken place and safety measures against such fire is under discussion at the International Maritime Organization (IMO). Early detection of fire is one of the essential elements of such safety measures. Location of fire detectors affects swiftness of detection of fire, and in onshore buildings, fire detectors are generally installed directly on ceilings because there are no obstacles under ceilings and smoke spreads along the ceilings. On the other hand, structures below ceilings, i.e., decks, of vehicle spaces are quite different from those of onshore buildings due to strength members below a deck, such as stiffeners and web beams. The appropriate positions of smoke detectors in a vehicle space, including vertical positions of detectors from a ceiling, has not been well-understood, while the maximum coverage of a detector is determined by an international regulation. In this study, the effect of structures below the ceilings of vehicle spaces on detection of fire has been investigated and the appropriate positions of smoke detectors including vertical positions have been considered, in particular, for smouldering fire sources. For this purpose, a one-sixth scaled deck model was prepared to simulate a part of a vehicle space and fire experiments were conducted using a small-scaled fire source. The effect of the structure on a smoke flow beneath the ceiling was experimentally investigated under the condition that the flow had a weak driving force in a smouldering fire or an early stage of fire. In the experiment, the flow was visualized using a laser and the smoke density expressed with the extinction coefficient was also measured. In addition, a small flaming fire source was used during the experiment, to further investigate a possibility of detection in an early stage of fire. The vertical profiles of smoke density were measured using the laser transmissometer. Furthermore, a smoke flow was visualized using continuous wave laser. As the results, it is concluded that it is appropriate to install smoke detectors at the lower end of the longitudinal stiffener, instead of installing on the ceilings in vehicle spaces.

Spent Fuel Pool Dose Rate Calculations Using Point Kernel and Hybrid Deterministic-Stochastic Shielding Methods

This paper presents comparison of the Krško Power Plant simplified Spent Fuel Pool (SFP) dose rates using different computational shielding methodologies. The analysis was performed to estimate limiting gamma dose rates on wall mounted level instrumentation in case of significant loss of cooling water. The SFP was represented with simple homogenized cylinders (point kernel and Monte Carlo (MC)) or cuboids (MC) using uranium, iron, water, and dry-air as a bulk region materials. The pool is divided on the old and new section where the old one has three additional subsections representing fuel assemblies (FAs) with different burnup/cooling time (60 days, 1 year and 5 years). The new section represents the FAs with the cooling time of 10 years. The time dependent fuel assembly isotopic composition was calculated using ORIGEN2 code applied to the depletion of one of the fuel assemblies present in the pool (AC-29). The source used in Microshield calculation is based on imported isotopic activities. The time dependent photon spectrum with total source intensity from Microshield multigroup point kernel calculations was then prepared for two hybrid deterministic-stochastic sequences. One is based on SCALE6.2b3/MAVRIC (Monaco and Denovo) methodology and another uses Monte Carlo code MCNP6.1.1b and ADVANTG3.0.1. code. Even though this model is a fairly simple one, the layers of shielding materials are thick enough to pose a significant shielding problem for MC method without the use of effective variance reduction (VR) technique. For that purpose the ADVANTG code was used to generate VR parameters for the MCNP fixed-source calculation using continuous energy transport. ADVATNG employs a deterministic forward-adjoint transport solver Denovo which implements CADIS/FWCADIS methodology. Denovo uses a structured, Cartesian-grid SN solver based on the Koch- Baker-Alcouffe parallel transport sweep algorithm across x-y domain blocks. This was our first application of ANDVANTG/MCNP hybrid sequence for this type of calculation and the results where compared to SCALE/MAVRIC sequence which we regularly use for similar calculations. The comparison of gamma dose rates on different point detector locations (central above pool and at the top of pool periphery) showed a good agreement between Microshield (point-kernel) and deterministic-stochastic shielding methodologies for the cylindrical approximation of the pool geometry. More complicated cases for model with multi-source option and for cuboids showed very good agreement between SCALE/MAVRIC and ANDVANTG/MCNP calculations.