Shielding Door Research Articles

Monte Carlo Simulation of Prompt Dose in the National Ignition Facility

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is the world’s largest and most powerful laser system for inertial confinement fusion. The NIF is a 192-laser beam facility that produces more than 2 MJ and 500 TW of ultraviolet light. The facility is expected to generate shots with varying fusion yield (up to 20 MJ or 7.1x1018 neutrons per shot) and a maximum annual yield of 1200 MJ. Monte Carlo simulations have been performed to estimate prompt dose values (neutrons and photons) inside the facility as well as at different locations outside the facility shield walls. The Target Chamber shielding, along with Target Bay and Switchyard walls, roofs, and doors will reduce exposures in occupied areas to acceptable levels. The thicknesses of the different shield doors in the facility were optimized such that prompt dose in occupied areas is limited to < 50 μSv per 20 MJ shot and < 1 mSv for 1200 MJ of annual fusion yield. Most of the normally occupied areas experience limited prompt dose values of < 50 μSv per shot. Low dose values are also expected outside the NIF facility. The maximum annual off-site dose to a maximally exposed individual is small and estimated at 24 μSv for 1200 MJ of fusion yield.

Research on the cable-driven endoscopic manipulator for fusion reactors

In this paper, a cable-driven endoscopic manipulator (CEM) is designed for the Chinese latest compact fusion reactor. The whole CEM arm is more than 3000 mm long and includes end vision tools, an endoscopic manipulator/control system, a feeding system, a drag chain system, support systems, a neutron shield door, etc. It can cover a range of ±45° of the vacuum chamber by working in a wrap-around mode, etc., to meet the need for observation at any position and angle. By placing all drive motors in the end drive box via a cable drive, cooling, and radiation protection of the entire robot can be facilitated. To address the CEM motion control problem, a discrete trajectory tracking method is proposed. By restricting each joint of the CEM to the target curve through segmental fitting, the trajectory tracking control is completed. To avoid the joint rotation angle overrun, a joint limit rotation angle optimization method is proposed based on the equivalent rod length principle. Finally, the CEM simulation system is established. The rationality of the structure design and the effectiveness of the motion control algorithm are verified by the simulation.

Study on neutron shielding performance of hot cell shielding door for nuclear power plant

Hot cell shielding door is an important component to ensure the safe operation of nuclear power plants. In this study, the shielding structure of hot cell shielding door is introduced. Using theoretical calculation of neutron shielding, Monte Carlo N-Particle Transport Code (MCNP) simulation analysis and experimental research, the neutron shielding performance of hot cell shielding door is studied. The results show that the neutron shielding ratio of both simulation and theoretical calculation reaches 98%, which meets the design requirements of neutron shielding performance. The experimental results show that when neutron energy is 5 MeV and thickness of boron containing plate is 40 mm, The neutron shielding ratio of three different composite materials, namely, steel plate + boron containing polyethylene plate + steel plate, steel plate + boron containing ultra-high molecular weight polyethylene plate + steel plate and steel plate + boron containing polypropylene plate + steel plate are 99.64%, and neutron shielding performance meets the index requirements. This study provides the choice of material and its thickness for hot cell shielding door.

Personnel Casualty Assessment for Explosion in the Subway Platform

The subway station is easy to be attacked by terrorist bombings, and it will cause heavy casualties. In this paper, a comprehensive casualty assessment method for personnel in the subway structure was established based on the existing personnel injury model. The spatial distribution characteristics of the shock wave suffered by the personnel in the subway platform were obtained. Combined with the comprehensive casualty assessment method, the personnel casualty area for the explosions in the subway platform was divided. The results show that for the same explosive charge, the maximum positive phase impulse generated by the explosion at the edge of the platform is smallest. The “notch effect” for the stair exit will increase the shock wave load. When the explosive is exploded in the center of the platform, the smaller the explosive charge is, the more obvious the “notch effect” is. When the explosive charge reaches 40 kg, the personnel safety area is reduced to a certain extent behind the stair except for the explosion happening at the stair. Also, the higher the shield door is, the larger the safety area behind the stair is.

Verification of the Thermal Neutron Shielding Effect of the Shielding Door of the LHD Experimental Hall

Evaluating the performance of the shielding walls and shielding doors at radiation facilities is important to ensure proper radiation safety management. In the first period of the deuterium experiment, the neutron-shielding ability of the shielding door of the experimental hall containing the large helical device (LHD) was evaluated using the gold-foil activation method. The gold foil was inserted into a small gap between the shielding door and the shielding wall. Meanwhile, the shielding effect of the wall against the neutrons and gamma rays was verified using the badge-type dosimeters that were placed both inside and outside the experimental hall near the wall. The radiation derived from Au-198, which was visualized using by imaging plate, reached approximately 35 cm inside the shielding door. The results provided visual evidence that the shielding door safely excluded the thermal neutrons that were generated in an LHD. Furthermore, the measurement results of the badge-type dosimeters confirmed that the neutrons and gamma rays were completely trapped by the concrete wall of the experimental hall.

Numerical Analysis of Wind Pressure at Subway Tunnel Platform Screen Door

In this paper, the calculation method of numerical simulation of compressible viscous flow field is used to establish the two-dimensional subway train and tunnel model. The wind pressure change of the piston is realized when the subway train passes through the platform at different speed grades. This paper mainly analyzes the distribution law of the wind pressure in the direction of the train running, and provides the wind pressure load data for the structural design of the shield door structure, and puts forward the recommended value of the pressure of the subway shield door when the train is running at 120km/h, To prevent the wind pressure on the shield door structure damage.

Design and Seismic Analysis of the Large Biological Shielding Door in Nuclear/Fusion Reactor

The large biological shielding door is the important protective equipment of nuclear/fusion reactor. Considering the seismic load and the gravity, it is designed. Based on the modal theory, the modal analysis is performed to obtain the natural frequency and the vibration modes of the door. Using the response spectrum method, the seismic analysis is performed to obtain the stress and displacement. Results show that the biological shielding door can meet the requirement of ASME and the design is reasonable and feasible; the horizontal acceleration being perpendicular to the door leaf is the major factor for the design of the door.

Accelerated Life Test Design of an Electromagnetic Shielding Door Hinge

Accelerated Life Test Design of an Electromagnetic Shielding Door Hinge

English

English

An analysis of dose reduction and the level of image quality attained by iDOSE

Radiotherapy services in Ireland have undergone extensive changes in terms of number and complexity of equipment installed in both public and private institutes in recent years. The latest addition to the ever growing number of sophisticated equipment was the unveiling of the CyberKnife facility at the Hermitage Medical Clinic. Due to planning restrictions the new facility had to be contained in the existing hospital’s blueprint with the only available location being an unused CT simulation room. The room design would be different from conventional radiotherapy bunkers due to the fact that the CyberKnife can fire an unfiltered beam in any direction except the roof (restriction of 220 above the horizontal). Therefore all walls must be primary barriers with the roof designed to protect against the large leakage radiation resulting from the high MUs used during the treatments. Space consideration indicated that concrete alone could not be used to restrict the radiation beam to acceptable limits. To this end a combination of steel, lead, normal and heavy concrete were used to meet the dose constraints established by the Irish licensing authorities. Novel designs to protect against ground shine and from primary and leakage radiation emerging under the direct shielding door had to be developed. Also many of the difficulties encountered during the design and conversion of the CT simulation room will be addressed.

The Design of Folio Shielding Door

Through analyzing a case of the design of a folio shielding door, the design and key technology of the equipment are shown.

Synthesis of ETP‐MMA and Lead Tetroxide Composites as Material for X‐Ray Radiation Shielding Door

SummaryManufacture of composite barrier X‐Ray radiation has been carried out by mixing Elastomer Thermoplastic‐Methyl Metacrylate (ETP‐MMA) with Pb3O4. The study was conducted with four variations: the variation of used rubber materials; the variation of rubber filler material composition; the variation of composite distance to the plane X‐rays; and the variations of composites thickness. Characterizations in this research are X‐ray radiation testing, mechanical testing, and scanning electron microscope (SEM) characterization. The characterizations show that the increasing of thermoplastic composition caused to the increasing of cavities, the reducing of radiation adsorption and the enhanching of mechanical properties. The addition of material composition gives an impact to the elevating of composite density, absorption of radiation, and hardness, but the decreasing of composite strength. Both thicker composite and greater distance between X‐ray machine resulting in greater radiation absorption. The best rubber material as the composite is TPE 30%. The largest composition is 500 phr. The optimum composition in the MMA‐TPE 50% is 435.82 phr with 0.4 cm of thickness. The optimum conditions of 50% MMA‐TPE composite with 0.2 cm of thickness is 168.19 cm in minimum distance between composite and X‐ray machine.

SU-E-T-200: IBA ProteusOne Compact Proton Therapy System Radiation Survey Results

Purpose: This study summarizes the results of an initial radiation survey of the Willis-Knighton Cancer Center in Shreveport, Louisiana. The facility houses an IBA ProteusOne compact single room proton therapy unit coupled with a C230 cyclotron that operates at a maximum energy of 230 MeV. Methods: A calibrated survey meter was used for the photon measurements to obtain reliable results. A neutron detector was used as the measuring instrument for neutrons. The locations of the survey and measurements were planned carefully in order to get a proper evaluation of the facility shielding configuration. The walls, ceiling, vault entrance, and the adjacent environment were each surveyed with suitable measurement instruments. A total of 22 locations were chosen for radiation survey. Dose equivalent values were calculated for both the photon and the neutron radiation using measured data. Results: All measured dose values are presented in millisievert per year. The highest dose measured at the vault entrance is 0.34 mSv/year. A dedicated shielding door was not present at the time of the measurement. The vault entrance area is considered as a controlled area. The shielding design goals are not to exceed 5 mSv/year for the controlled area and 1 mSv/year the uncontrolled area. The total combined neutron and photon dose equivalent values were found to be compliant with the Louisiana Department of Environmental Quality radiation protection regulatory codes. Conclusion: In our efforts to evaluate the radiation levels at the Willis-Knighton Cancer Center proton treatment facility, we have found that all the measured values of the radiation shielding are below the critical radiation limits per year. Since the total dose measured at the vault entrance is below the shielding design goal, a shielding door is not required at this proton treatment vault.

Wideband Shield Door With a Magnetic Absorber

It is necessary to secure a high shielding performance in a wide frequency range for a shield room to defend electrical equipment from high-power electromagnetic (HPEM) threat environments. We proposed a novel shield door with gaskets and magnetic absorbers. The magnetic losses of the magnetic absorbers realize the large shield effectiveness without impairing the door operability. The structures of magnetic absorbers are investigated through finite-difference time-domain (FDTD) analysis and experiments. We found that the multi-layered magnetic absorbers increase the shield effectiveness by 15 dB over a wide frequency range. Therefore, it is found that using the magnetic absorbers, high shielding performance can be achieved without impairing the door operability, which can provide an effective protection from the HPEM environments.

Radiological Design Aspects of the National Ignition Facility

The National Ignition Facility (NIF) has been designed to accommodate some challenging radiological conditions. The high prompt neutron source (up to 1.6 × 10(19) neutrons per shot) results in the need for significant fixed shielding. Concrete shielding approximately 2 m thick is used for the primary (target bay) shield. Penetrations in this shield, including those required for 192 laser beams, utilities, diagnostics, and 19 shielded personnel access doors, make the design challenging. An additional 28 shield doors are part of the secondary shield. In addition, the prompt neutron pulse results in activated air within the target bay, requiring special ventilation considerations. Finally, targets can use a number of hazardous and radioactive materials including tritium, beryllium, and depleted uranium (the latter of which results in the generation of small quantities of fission products). Frequent access is required to the associated potentially contaminated volumes for experimental setup, facilitating the need for local exhaust ventilation to manage these hazards. This paper reviews some of these challenges, design considerations, and the engineering solutions to these design requirements.

치과 방사선 검사 시 노출 위험성에 따른 피폭선량 방어연구

일반적으로 저 에너지 방사선 조사로 검사하게 되는 치과 영역에서는 투과력이 약해 인체에 흡수되는 양이 많다. 치과 영역에서 방사선검사 시 부득이하게 방사선 노출을 받게 되는 방사선 작업종사자나 환자의 보호자가 위치와 거리에 따른 방사선 피폭 선량의 감소 방안을 알아보고자 한다. 진단용 발생장치인 GX-770, CRANEX TOME CEPH와 조사선량 측정기인 Ion chamber model 2026c, Reader기 20X6-1800을 사용하여 구강내 검사와 구강외 검사의 각각 검사실과 조정실에서의 관전압의 변화, 관전류와 조사시간의 변화, 조사방향의 변화에 따라 선량을 측정하였다. 그 결과 최고선량이 검사실 안에서는 평균 702.8 <TEX>${\mu}R$</TEX>으로 측정 되었으며, 조정실 안에서 측정하였을 경우 20 <TEX>${\mu}R$</TEX>이하의 낮은 선량을 보였으며, 120cm 거리에서 후방검사보다 측방검사가 낮은 선량으로 나타났다. 방사선검사시 위치와 거리에 따른 조사선량을 비교 분석하여, 적절한 거리 확보와 조사되는 중심방사선을 기준으로 측방(<TEX>$90{\sim}135^{\circ}$</TEX>)에 위치함으로써 방사선 방어에 도움을 줄 것이며, 차폐문을 이용하여 방사선 피폭으로부터 감소 효과를 볼 수 있을 것이다. Generally, X-ray examinations for dentistry use low energy radiation. It explains that the radiations are mainly absorbed to a human body because of the weak permeability. We made up some counterplans for decrease in radiation exposure, when guardians and radiologists are overexposed owing to unavoidable circumstances. The equipments for the test are GX-770 and CRANEX TOME CEPH which are used for various exams. Besides we measured the radiations in the projection room and in the control room using model 2026c and 20X6-1800. According to the test, the measurement value in the control room was low dose below <TEX>$20{\mu}R$</TEX>, the maximum dose in the projection room was <TEX>$702.8{\mu}R$</TEX> and the measurement value of back dose was higher than lateral one. As the result, if we use a shielding door, it's effective for radioprotection and when we didn't prepare protectors, we should secure appropriate distance and be situated at the side area(<TEX>$90{\sim}135^{\circ}$</TEX>) on the basis of centeral radiation. That way will provide valuable aid for radioprotection.

Experimental Study of Smoke Control in Subway Station for Tunnel Area Fire by Water Mist System

Full scale experiments were performed in an underground subway station to investigate the effect of water mist on smoke flow from tunnel area to platform through shield door. Smoke temperature, species concentrations and smoke visibility were measured at different points. Dimensionless variables were introduced to represent the variations of smoke characteristics. The smoke temperature with water mist interaction could be reduced to less than 1/10 of the spill smoke flow. The mass flow rate could be reduced to less than 1/4 of the spill smoke flow. The experimental results indicated that the water mist system could help to reduce smoke temperature and the concentration of toxic species, improving survival conditions for evacuations of passengers.

Evaluation of Prompt Dose Environment in the National Ignition Facility during D-D and THD Shots

Evaluation of the prompt dose environment expected in the National Ignition Facility (NIF) during Deuterium-Deuterium (D-D) and Tritium-Hydrogen-Deuterium (THD) shots have been completed. D-D shots resulting in the production of an annual fusion yield of up to 2.4 kJ (200 shots with 1013 neutrons per shot) are considered. During the THD shot campaign, shots generating a total of 2x1014 neutrons per shot are also planned. Monte Carlo simulations have been performed to estimate prompt dose values inside the facility as well as at different locations outside the facility shield walls. The Target Chamber shielding, along with Target Bay and Switchyard walls, roofs, and shield doors (when needed) will reduce dose levels in occupied areas to acceptable values during these shot campaigns. The calculated dose values inside occupied areas are small, estimated at 25 and 85 μrem per shot during the D-D and THD shots, respectively. Dose values outside the facility are insignificant. The nearest building to the NIF facility where co-located workers may reside is at a distance of about 100 m from the Target Chamber Center (TCC). The dose in such a building is estimated at a fraction of a rem during a D-D or a THD shot. Dose at the nearest site boundary location (350 m from TCC), is caused by skyshine and to a lesser extent by direct radiation. The maximum off-site dose during any of the shots considered is less than 10 nano rem.

Analysis and improvement of cyclotron thallium target room shield

Because of high neutron and gamma-ray intensities generated during bombardment of a thallium-203 target, a thallium target-room shield and different ways of improving it have been investigated. Leakage of neutron and gamma ray dose rates at various points behind the shield are calculated by simulating the transport of neutrons and photons using the Monte Carlo N Particle transport computer code. By considering target-room geometry, its associated shield and neutron and gamma ray source strengths and spectra, three designs for enhancing shield performance have been analysed: a shielding door at the maze entrance, covering maze walls with layers of some effective materials and adding a shadow-shield in the target room in front of the radiation source. Dose calculations were carried out separately for different materials and dimensions for all the shielding scenarios considered. The shadow-shield has been demonstrated to be one suitable for neutron and gamma dose equivalent reduction. A 7.5-cm thick polyethylene shadow-shield reduces both dose equivalent rate at maze entrance door and leakage from the shield by a factor of 3.

도어 모듈 플레이트의 동특성 분석에 관한 연구

Currently, automotive industries improve the vehicle performance and reduce the development period of vehicle using each module part for the high quality and performance of vehicles. However each component part doesn't generate the noise and vibration problems, sometime these problems are generated on the assembly status between vehicle chassis frame and each module part. On this study, in order to analysis the dynamic characteristics of a shield door module that is a typical module part of vehicles, the acquisition and evaluation process about the vibration and noise of shield door module is developed. Also the possibility to apply to shield door module of the developed process is verified by the comparison with the dynamic characteristics between plastic and steel module plate.