76 FR 63942 - Notice of Issuance of Final Determination Concerning a Surgical Mask With a Protective Eye Shield

Science.gov (United States)

2011-10-14

... Determination Concerning a Surgical Mask With a Protective Eye Shield AGENCY: U.S. Customs and Border Protection... country of origin of a Surgical Mask with a Protective Eye Shield. Based upon the facts presented, CBP has concluded in the final determination that Turkey is the country of origin of the Surgical Mask with a...

Protective shielding parameters of diagnostic x-ray rooms in some hospitals in Benue State

International Nuclear Information System (INIS)

Agba, E.H.; Gemanam, S.; Sombo, T.

2011-01-01

Protective shielding parameters of diagnostic x-ray units at Federal Medical Centre, Makurdi, Baki Hospital, Gboko and Mkar Christian Hospital, Gboko have been determined using a radiation meter, (Inspector, Exp.S.E). The parameters determined include: Operating potential, Workload and Use factors of each diagnostic x-ray room. These parameters were used to estimate the primary and secondary protective barriers for the hospitals. The primary and secondary protective barrier values at Mkar Christian Hospital, Baki Hospital, Gboko and Federal Medical Centre, Makurdi are found to be: 11.0±0.11 x10 -1 mm and 9.0±9x10 -2 mm; 6.0±6.0x10 -1 mm and 6.0±6.0x10 -2 mm; and 7.0±7.0x10 -1 mm and 6.0±6.0x10 -2 mm respectively. The wall thicknesses around the x-ray rooms of the respective hospitals are 300±3.0x1 0 -1 mm for Mkar Christian Hospital and Federal Medical Centre, Makurdi, while that of Baki Hospital, Gboko is 270±2.7x10 -1 mm. The measured wall thicknesses are seen to be adequate protective structural shields on the basis of International NCRP Standards on Structural Shielding.

Strengthening the composite protective shield of light-weight ship against ballistic impacts: analytical and experimental

Directory of Open Access Journals (Sweden)

I. Jalili

Full Text Available Light and medium protection for small naval vessels guarantees their high performance and safety during the guard duties. In this study, a protective shield fabricated from Dyneema HB25 fibers has been utilized as an add-on layer on the coast guard boat hull. Finite element analyses have been conducted using Chocron's model. Two standards of gun-fire were employed and various thicknesses of the composite layers were examined by ballistic impacts. Afterward, numerical simulations results compared with experiments and revealed a good consistency. Finally, some graphs have been presented to help designers for choosing more convenient shield based on protection and weight characteristics after judgment of vessel requirements.

A Shifting Shield Provides Protection Against Cosmic Rays

Science.gov (United States)

Kohler, Susanna

2017-12-01

The Sun plays an important role in protecting us from cosmic rays, energetic particles that pelt us from outside our solar system. But can we predict when and how it will provide the most protection, and use this to minimize the damage to both pilotedand roboticspace missions?The Challenge of Cosmic RaysSpacecraft outside of Earths atmosphere and magnetic field are at risk of damage from cosmic rays. [ESA]Galactic cosmic rays are high-energy, charged particles that originate from astrophysical processes like supernovae or even distant active galactic nuclei outside of our solar system.One reason to care about the cosmic rays arriving near Earth is because these particles can provide a significant challenge for space missions traveling above Earths protective atmosphere and magnetic field. Since impacts from cosmic rays can damage human DNA, this risk poses a major barrier to plans for interplanetary travel by crewed spacecraft. And roboticmissions arent safe either: cosmic rays can flip bits, wreaking havoc on spacecraft electronics as well.The magnetic field carried by the solar wind provides a protective shield, deflecting galactic cosmic rays from our solar system. [Walt Feimer/NASA GSFCs Conceptual Image Lab]Shielded by the SunConveniently, we do have some broader protection against galactic cosmic rays: a built-in shield provided by the Sun. The interplanetary magnetic field, which is embedded in the solar wind, deflects low-energy cosmic rays from us at the outer reaches of our solar system, decreasing the flux of these cosmic rays that reach us at Earth.This shield, however, isnt stationary; instead, it moves and changes as the strength and direction of the solar wind moves and changes. This results in a much lower cosmic-ray flux at Earth when solar activity is high i.e., at the peak of the 11-year solar cycle than when solar activity is low. This visible change in local cosmic-ray flux with solar activity is known as solar modulation of the cosmic ray flux

Surface protection in bio-shields via a functional soft skin layer: Lessons from the turtle shell.

Science.gov (United States)

Shelef, Yaniv; Bar-On, Benny

2017-09-01

The turtle shell is a functional bio-shielding element, which has evolved naturally to provide protection against predator attacks that involve biting and clawing. The near-surface architecture of the turtle shell includes a soft bi-layer skin coating - rather than a hard exterior - which functions as a first line of defense against surface damage. This architecture represents a novel type of bio-shielding configuration, namely, an inverse structural-mechanical design, rather than the hard-coated bio-shielding elements identified so far. In the current study, we used experimentally based structural modeling and FE simulations to analyze the mechanical significance of this unconventional protection architecture in terms of resistance to surface damage upon extensive indentations. We found that the functional bi-layer skin of the turtle shell, which provides graded (soft-softer-hard) mechanical characteristics to the bio-shield exterior, serves as a bumper-buffer mechanism. This material-level adaptation protects the inner core from the highly localized indentation loads via stress delocalization and extensive near-surface plasticity. The newly revealed functional bi-layer coating architecture can potentially be adapted, using synthetic materials, to considerably enhance the surface load-bearing capabilities of various engineering configurations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of Radiation Protection Methodologies for Radiation Therapy Shielding Using Monte Carlo Simulation and Measurement

Science.gov (United States)

Tanny, Sean

The advent of high-energy linear accelerators for dedicated medical use in the 1950's by Henry Kaplan and the Stanford University physics department began a revolution in radiation oncology. Today, linear accelerators are the standard of care for modern radiation therapy and can generate high-energy beams that can produce tens of Gy per minute at isocenter. This creates a need for a large amount of shielding material to properly protect members of the public and hospital staff. Standardized vault designs and guidance on shielding properties of various materials are provided by the National Council on Radiation Protection (NCRP) Report 151. However, physicists are seeking ways to minimize the footprint and volume of shielding material needed which leads to the use of non-standard vault configurations and less-studied materials, such as high-density concrete. The University of Toledo Dana Cancer Center has utilized both of these methods to minimize the cost and spatial footprint of the requisite radiation shielding. To ensure a safe work environment, computer simulations were performed to verify the attenuation properties and shielding workloads produced by a variety of situations where standard recommendations and guidance documents were insufficient. This project studies two areas of concern that are not addressed by NCRP 151, the radiation shielding workload for the vault door with a non-standard design, and the attenuation properties of high-density concrete for both photon and neutron radiation. Simulations have been performed using a Monte-Carlo code produced by the Los Alamos National Lab (LANL), Monte Carlo Neutrons, Photons 5 (MCNP5). Measurements have been performed using a shielding test port designed into the maze of the Varian Edge treatment vault.

Guideline on radiation protection requirements for ionizing radiation shielding in nuclear power plants

International Nuclear Information System (INIS)

1988-01-01

The guideline which entered into force on 1 May 1988 stipulates the radiation protection requirements for shielding against ionizing radiation to be met in the design, construction, commissioning, operation, and decommissioning of nuclear power plants

Shielding in experimental areas

International Nuclear Information System (INIS)

Stevens, A.; Tarnopolsky, G.; Thorndike, A.; White, S.

1979-01-01

The amount of shielding necessary to protect experimental detectors from various sources of background radiation is discussed. As illustrated an experiment has line of sight to sources extending approx. 90 m upstream from the intersection point. Packing a significant fraction of this space with shielding blocks would in general be unacceptable because primary access to the ring tunnel is from the experimental halls. (1) From basic machine design considerations and the inherent necessity to protect superconducting magnets it is expected that experimental areas in general will be cleaner than at any existing accelerator. (2) Even so, it will likely be necessary to have some shielding blocks available to protect experimental apparatus, and it may well be necessary to have a large amount of shielding available in the WAH. (3) Scraping will likely have some influence on all halls, and retractable apparatus may sometimes be necessary. (4) If access to any tunnel is needed to replace a magnet, one has 96 h (4 days) available to move shielding away to permit access without additional downtime. This (the amount of shielding one can shuffle about in 96 h) is a reasonable upper limit to shielding necessary in a hall

Shielded chamber control stations: an answer to radiological protection requirements

International Nuclear Information System (INIS)

Delaboudiniere, Catherine.

1979-06-01

This study, carried out at the radiometallurgy laboratory of the Fontenay-aux-Roses Nuclear Research Centre, is based on an ergonomic approach. It shows that the shielded chamber control station, designed for human protection against ionizing radiations, demands an effort of adaptation on the part of the operator. This station does in fact meet radiological protection obligations but would benefit from certain improvements aimed at reducing the secondary fatigue of manipulators already under the strain of adapting to the machine. Fields in which improvements and/or changes are desirable have been investigated with special reference to telemanipulators. New and better designed instruments will soon appear on the telemanipulator market [fr

A novel redox-based switch: LMW-PTP oxidation enhances Grb2 binding and leads to ERK activation

International Nuclear Information System (INIS)

Giannoni, Elisa; Raugei, Giovanni; Chiarugi, Paola; Ramponi, Giampietro

2006-01-01

Low molecular weight-PTP has been reported as a redox-sensitive protein during both platelet-derived growth factor and integrin signalling. In response to oxidation the phosphatase undergoes a reversible inactivation, which in turn leads to the increase in tyrosine phosphorylation of its substrates and the properly executed anchorage-dependent proliferation program. Here, we report that an exogenous oxidative stress enhances LMW-PTP tyrosine phosphorylation, through oxidation/inactivation of the enzyme, thus preventing its auto-dephosphorylation activity. In particular, we observed a selective hyper-phosphorylation of Tyr132, that acts as a docking site for the adaptor protein Grb2. The redox-dependent enhancement of Grb2 recruitment to LMW-PTP ultimately leads to an improvement of ERK activation, likely triggering a prosurvival signal against the oxidant environment

Analysis and Testing of a Composite Fuselage Shield for Open Rotor Engine Blade-Out Protection

Science.gov (United States)

Pereira, J. Michael; Emmerling, William; Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Carney, Kelly S.

2016-01-01

The Federal Aviation Administration is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the Aircraft. The NASA Glenn Research Center and The Naval Air Warfare Center (NAWC), China Lake, collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test lightweight composite shields for protection of the aircraft passengers and critical systems from a released blade that could impact the fuselage. LS-DYNA® was used to predict the thickness of the composite shield required to prevent blade penetration. In the test, two composite blades were pyrotechnically released from a running engine, each impacting a composite shield with a different thickness. The thinner shield was penetrated by the blade and the thicker shield prevented penetration. This was consistent with pre-test LS-DYNA predictions. This paper documents the analysis conducted to predict the required thickness of a composite shield, the live fire test from the full scale rig at NAWC China Lake and describes the damage to the shields as well as instrumentation results.

About the Scythian Shields

Directory of Open Access Journals (Sweden)

About the Scythian Shields

2017-10-01

Full Text Available Shields played major role in the armament system of the Scythians. Made from organic materials, they are poorly traced on the materials of archaeological excavations. Besides, scaly surface of shields was often perceived in practice as the remnants of the scaly armor. E. V. Chernenko was able to discern the difference between shields’ scaly plates and armor scales. The top edge of the scales was bent inwards, and shield plates had a wire fixation. These observations let significantly increase the number of shields, found in the burial complexes of the Scythians. The comparison of archaeological materials and the images of Scythian warriors allow distinguishing the main forms of Scythian shields. All shields are divided into fencing shields and cover shields. The fencing shields include round wooden shields, reinforced with bronze sheet, and round moon-shaped shields with a notch at the top, with a metal scaly surface. They came to the Scythians under the Greek influence and are known in the monuments of the 4th century BC. Oval shields with scaly surface (back cover shields were used by the Scythian cavalry. They protected the rider in case of frontal attack, and moved back in case of maneuver or closein fighting. Scythian battle tactics were based on rapid approaching the enemy and throwing spears and further rapid withdrawal. Spears stuck in the shields of enemies, forcing them to drop the shields, uncover, and in this stage of the battle the archers attacked the disorganized ranks of the enemy. That was followed by the stage of close fight. Oval form of a wooden shield with leather covering was used by the Scythian infantry and spearmen. Rectangular shields, including wooden shields and the shields pleached from rods, represented a special category. The top of such shield was made of wood, and a pleached pad on leather basis was attached to it. This shield could be a reliable protection from arrows, but it could not protect against javelins

Shielding and filtering techniques to protect sensitive instrumentation from electromagnetic interference caused by arc welding

International Nuclear Information System (INIS)

Kalechstein, W.

1997-01-01

Electromagnetic interference (EMI) caused by arc welding is a concern for sensitive CANDU instrumentation and control equipment, especially start-up instrumentation (SUI) and ion chamber instruments used to measure neutron flux at low power. Measurements of the effectiveness of simple shielding and filtering techniques that may be applied to limit arc welding electromagnetic emissions below the interference threshold are described. Shielding configurations investigated include an arrangement in which the welding power supply, torch (electrode holder), interconnecting cables and welder operator were housed in a single enclosure and a more practical configuration of separate shields for the power supply, cables and operator with torch. The two configuration were found to provide 30 dB and 26 dB attenuation, respectively, for arc welder electric-field emissions and were successful in preventing EMI in SUI set up just outside the shielding enclosures. Practical improvements that may be incorporated in the shielding arrangement to facilitate quick setup in the field in a variety of application environments, while maintaining adequate EMI protection, are discussed. (author)

[Eye lens radiation exposure during ureteroscopy with and without a face protection shield: Investigations on a phantom model].

Science.gov (United States)

Zöller, G; Figel, M; Denk, J; Schulz, K; Sabo, A

2016-03-01

Eye lens radiation exposure during radiologically-guided endoscopic procedures may result in radiation-induced cataracts; therefore, we investigated the ocular radiation exposure during ureteroscopy on a phantom model. Using an Alderson phantom model and eye lens dosimeters, we measured the ocular radiation exposure depending on the number of X-ray images and on the duration of fluoroscopic imaging. The measurements were done with and without using a face protection shield. We could demonstrate that a significant ocular radiation exposure can occur, depending on the number of X-ray images and on the duration time of fluoroscopy. Eye lens doses up to 0.025 mSv were recorded even using modern digital X-ray systems. Using face protection shields this ocular radiation exposure can be reduced to a minimum. The International Commission on Radiological Protection (ICRP) recommendations of a mean eye lens dosage of 20 mSv/year may be exceeded during repeated ureteroscopy by a high volume surgeon. Using a face protection shield, the eye lens dose during ureteroscopy could be reduced to a minimum in a phantom model. Further investigations will show whether these results can be transferred to real life ureteroscopic procedures.

SU-E-T-243: Design of a Novel Testing Port for Radiation Protection and Shielding Measurements

International Nuclear Information System (INIS)

Tanny, S; Parsai, E; Harrell, D; Noller, J; Chopra, M

2015-01-01

Purpose: The majority of radiation shielding research utilizes Monte Carlo simulation because of the difficulty in eliminating secondary radiations from measurements. We have designed a test port into a primary barrier of our newest vault to allow for shielding measurements while ensuring adequate protection to the public and staff during normal machine operation. This port allows for measurement of attenuation values of shielding materials, differential dose albedos, and radiation scatter fractions. Methods: The vault design utilized the maze as part of a compound primary barrier. The test port is contained within the maze and is centered along isocenter. The inner 30 cm has a 20×20 cm 2 opening, while the remaining length has a 30×30 cm 2 opening. The block that contains the port has a density of 200 pcf to minimize internal scatter. The 30×30 cm 2 opening is occupied by removable 215 pcf concrete blocks. The innermost and outermost blocks activate an interlock wired into the beam-enable loop. This disallows beam-on in treatment mode if the interlock isn’t closed. The interlock can be overridden in service mode, or by-passed via an override switch in case of circuit failure. Results: The test port was installed in August. The beam is disabled when the interlock is tripped. Measurements taken when the primary beam is not incident on the port are indistinguishable from background. Ambient dose levels surrounding the vault with the designed shielding blocks in place are all within allowable limits for occupational workers. Conclusions: We have designed and installed a unique testing port for radiation protection and shielding measurements. This port is appropriately interlocked and designed to mitigate any risks of incidental exposure to staff or members of the public. The test port design allows measurements with “good geometry” and efficient removal of contaminating sources of radiation present in many shielding measurements. Daniel Harrell and Jim Noller

Gonad shielding in diagnostic radiology

International Nuclear Information System (INIS)

Anon.

1975-01-01

The use of gonad shielding is an important radiation protection technique, intended to reduce unnecessary x-ray exposure of the gonads of patients from diagnostic x-ray procedures. The types of gonad shields in use are discussed as are the types of diagnostic examinations that should include gonad shielding. It was found that when properly used, most shields provided substantial gonad dose reductions

Experimental shielding evaluation of the radiation protection provided by the structurally significant components of residential structures.

Science.gov (United States)

Dickson, E D; Hamby, D M

2014-03-01

The human health and environmental effects following a postulated accidental release of radioactive material to the environment have been a public and regulatory concern since the early development of nuclear technology. These postulated releases have been researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to provide an updated technical basis for contemporary building shielding factors for the US housing stock. Building shielding factors quantify the protection from ionising radiation provided by a certain building type. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950s era suburbia and is no longer applicable to the densely populated urban environments realised today. To analyse a building's radiation shielding properties, the ideal approach would be to subject a variety of building types to various radioactive sources and measure the radiation levels in and around the building. While this is not entirely practicable, this research analyses the shielding effectiveness of ten structurally significant US housing-stock models (walls and roofs) important for shielding against ionising radiation. The experimental data are used to benchmark computational models to calculate the shielding effectiveness of various building configurations under investigation from two types of realistic environmental source terms. Various combinations of these ten shielding models can be used to develop full-scale computational housing-unit models for building shielding factor calculations representing 69.6 million housing units (61.3%) in the United States. Results produced in this investigation provide a comparison between theory and experiment behind building shielding factor methodology.

Experimental shielding evaluation of the radiation protection provided by the structurally significant components of residential structures

International Nuclear Information System (INIS)

Dickson, E D; Hamby, D M

2014-01-01

The human health and environmental effects following a postulated accidental release of radioactive material to the environment have been a public and regulatory concern since the early development of nuclear technology. These postulated releases have been researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to provide an updated technical basis for contemporary building shielding factors for the US housing stock. Building shielding factors quantify the protection from ionising radiation provided by a certain building type. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950s era suburbia and is no longer applicable to the densely populated urban environments realised today. To analyse a building’s radiation shielding properties, the ideal approach would be to subject a variety of building types to various radioactive sources and measure the radiation levels in and around the building. While this is not entirely practicable, this research analyses the shielding effectiveness of ten structurally significant US housing-stock models (walls and roofs) important for shielding against ionising radiation. The experimental data are used to benchmark computational models to calculate the shielding effectiveness of various building configurations under investigation from two types of realistic environmental source terms. Various combinations of these ten shielding models can be used to develop full-scale computational housing-unit models for building shielding factor calculations representing 69.6 million housing units (61.3%) in the United States. Results produced in this investigation provide a comparison between theory and experiment behind building shielding factor methodology. (paper)

Survey of radiation protection, radiation transport, and shielding information needs of the nuclear power industry. Final report

International Nuclear Information System (INIS)

Maskewitz, B.F.; Trubey, D.K.; Roussin, R.W.; McGill, B.L.

1976-04-01

The Radiation Shielding Information Center (RSIC) is engaged in a program to seek out, organize, and disseminate information in the area of radiation transport, shielding, and radiation protection. This information consists of published literature, nuclear data, and computer codes and advanced analytical techniques required by ERDA, its contractors, and the nuclear power industry to improve radiation analysis and computing capability. Information generated in this effort becomes a part of the RSIC collection and/or data base. The purpose of this report on project 219-1 is to document the results of the survey of information and computer code needs of the nuclear power industry in the area of radiation analysis and protection

Survey of radiation protection, radiation transport, and shielding information needs of the nuclear power industry. Final report

Energy Technology Data Exchange (ETDEWEB)

Maskewitz, B.F.; Trubey, D.K.; Roussin, R.W.; McGill, B.L.

1976-04-01

The Radiation Shielding Information Center (RSIC) is engaged in a program to seek out, organize, and disseminate information in the area of radiation transport, shielding, and radiation protection. This information consists of published literature, nuclear data, and computer codes and advanced analytical techniques required by ERDA, its contractors, and the nuclear power industry to improve radiation analysis and computing capability. Information generated in this effort becomes a part of the RSIC collection and/or data base. The purpose of this report on project 219-1 is to document the results of the survey of information and computer code needs of the nuclear power industry in the area of radiation analysis and protection.

Velcro-Like System Used to Fix a Protective Faecal Shield on Weevil Larvae.

Science.gov (United States)

Skuhrovec, Jiří; Stejskal, Robert; Trnka, Filip; di Giulio, Andrea

2017-01-01

The last instar larva and pupa of Eucoeliodes mirabilis (A. Villa & G. B. Villa, 1835) (Curculionidae: Ceutorhynchini) are described using drawings and SEM images and are compared and keyed with already described larvae of 58 other ceutorhynchinae taxa. The larval body has an effective combination of morphological adaptations that assist a unique biological defensive strategy. All larval stages of E. mirabilis feed ectophytically on leaves of Euonymus europaeus L. (Celastraceae), and the larval body is covered with a thick faecal shield. The fixation of this protective shield on the larval back is performed by a peculiar dorsal microsculpture composed of a dense carpet of microtrichia on the thorax and abdomen, which serves effectively as a velcro system. Because of this strategy, macrosetae on the larval and pupal body of E. mirabilis are completely reduced. Larvae of E. mirabilis also have distinct morphological adaptations for protecting the spiracles against intrusion of faeces and avoiding occlusion of the tracheal system: a) microtrichia around spiracles are slightly shorter, distinctly stronger and are arranged with high-density and in clusters and b) spiracles are protected by an external safety valve. This strategy of E. mirabilis larvae is unique, although somewhat similar to that of Criocerinae and Blepharida-group leave beetles (Galerucinae) (both Coleoptera: Chrysomelidae), but with distinctly different morphological adaptations.

ANS shielding standards for light-water reactors

International Nuclear Information System (INIS)

Trubey, D.K.

1982-01-01

The purpose of the American Nuclear Society Standards Subcommittee, ANS-6, Radiation Protection and Shielding, is to develop standards for radiation protection and shield design, to provide shielding information to other standards-writing groups, and to develop standard reference shielding data and test problems. A total of seven published ANS-6 standards are now current. Additional projects of the subcommittee, now composed of nine working groups, include: standard reference data for multigroup cross sections, gamma-ray absorption coefficients and buildup factors, additional benchwork problems for shielding problems and energy spectrum unfolding, power plant zoning design for normal and accident conditions, process radiation monitors, and design for postaccident radiological conditions

Effective protection of biological membranes against photo-oxidative damage: Polymeric antioxidant forming a protecting shield over the membrane.

Science.gov (United States)

Mertins, Omar; Mathews, Patrick D; Gomide, Andreza B; Baptista, Mauricio S; Itri, Rosangela

2015-10-01

We have prepared a chitosan polymer modified with gallic acid in order to develop an efficient protection strategy biological membranes against photodamage. Lipid bilayers were challenged with photoinduced damage by photosensitization with methylene blue, which usually causes formation of hydroperoxides, increasing area per lipid, and afterwards allowing leakage of internal materials. The damage was delayed by a solution of gallic acid in a concentration dependent manner, but further suppressed by the polymer at very low concentrations. The membrane of giant unilamellar vesicles was covered with this modified macromolecule leading to a powerful shield against singlet oxygen and thus effectively protecting the lipid membrane from oxidative stress. The results have proven the discovery of a promising strategy for photo protection of biological membranes. Copyright © 2015 Elsevier B.V. All rights reserved.

Onboard cross-calibration of the Pille-ISS Detector System and measurement of radiation shielding effect of the water filled protective curtain in the ISS crew cabin

International Nuclear Information System (INIS)

Szántó, P.; Apáthy, I.; Deme, S.; Hirn, A.; Nikolaev, I.V.; Pázmándi, T.; Shurshakov, V.A.; Tolochek, R.V.; Yarmanova, E.N.

2015-01-01

As a preparation for long duration space missions it is important to determine and minimize the impact of space radiation on human health. One of the methods to diminish the radiation burden is using an additional local shielding in the places where the crewmembers can stay for longer time. To increase the crew cabin shielding a special protective curtain was designed and delivered to ISS in 2010 containing four layers of hygienic wipes and towels providing an additional shielding thickness of about 8 g/cm"2 water-equivalent matter. The radiation shielding effect of the protective curtain, in terms of absorbed dose, was measured with the thermoluminescent Pille-ISS Detector System. In order to verify the reliability of the Pille system an onboard cross-calibration was also performed. The measurement proved that potentially 25% reduction of the absorbed dose rate in the crew cabin can be achieved, that results in 8% (∼16 μGy/day) decrease of the total absorbed dose to the crew, assuming that they spend 8 h in the crew cabin a day. - Highlights: • The dose level in the ISS Zvezda crew quarters is higher than the average dose level in the module. • A shielding made of hygienic wipes and towels was set up onboard as additional protection. • Onboard cross calibration of the Pille-ISS space dosimeter (TL) system was performed. • The shielding effect of the protective curtain in terms of absorbed dose was measured with the onboard Pille system. • The shielding effect of the protective water curtain is approximately 24 ± 9% in absorbed dose.

Design experience: CRBRP radiation shielding

International Nuclear Information System (INIS)

Disney, R.K.; Chan, T.C.; Gallo, F.G.; Hedgecock, L.R.; McGinnis, C.A.; Wrights, G.N.

1978-11-01

The Clinch River Breeder Reactor Plant (CRBRP) is being designed as a fast breeder demonstration project in the U.S. Liquid Metal Fast Breeder Reactor (LMFBR) program. Radiation shielding design of the facility consists of a comprehensive design approach to assure compliance with design and government regulatory requirements. Studies conducted during the CRBRP design process involved the aspects of radiation shielding dealing with protection of components, systems, and personnel from radiation exposure. Achievement of feasible designs, while considering the mechanical, structural, nuclear, and thermal performance of the component or system, has required judicious trade-offs in radiation shielding performance. Specific design problems which have been addressed are in-vessel radial shielding to protect permanent core support structures, flux monitor system shielding to isolate flux monitoring systems for extraneous background sources, reactor vessel support shielding to allow personnel access to the closure head during full power operation, and primary heat transport system pipe chaseway shielding to limit intermediate heat transport system sodium system coolant activation. The shielding design solutions to these problems defined a need for prototypic or benchmark experiments to provide assurance of the predicted shielding performance of selected design solutions and the verification of design methodology. Design activities of CRBRP plant components an systems, which have the potential for radiation exposure of plant personnel during operation or maintenance, are controlled by a design review process related to radiation shielding. The program implements design objectives, design requirements, and cost/benefit guidelines to assure that radiation exposures will be ''as low as reasonably achievable''

The Fabrication of Internal Shielding using Provil and Cerrobend

International Nuclear Information System (INIS)

Kim Jong Hwa; Lee, Kang Hyun; Son, Jeong Hye

1996-01-01

The skin cancer is a highly curable disease which frequently occurs in the head and neck region exposed to the sun. When the eyelid is treated usually eye shield made of lead is used to protect the eyeball as a internal shield. For the same reason on internal shield should be used when the nose is treated when electron to protect the nasal mucosa. Our hospital made an internal shield for the treatment of the skin cancer on the nose using provil and cerrobend. The characteristics of the internal shield were examined.

A model-based approach of scatter dose contributions and efficiency of apron shielding for radiation protection in CT.

Science.gov (United States)

Weber, N; Monnin, P; Elandoy, C; Ding, S

2015-12-01

Given the contribution of scattered radiations to patient dose in CT, apron shielding is often used for radiation protection. In this study the efficiency of apron was assessed with a model-based approach of the contributions of the four scatter sources in CT, i.e. external scattered radiations from the tube and table, internal scatter from the patient and backscatter from the shielding. For this purpose, CTDI phantoms filled with thermoluminescent dosimeters were scanned without apron, and then with an apron at 0, 2.5 and 5 cm from the primary field. Scatter from the tube was measured separately in air. The scatter contributions were separated and mathematically modelled. The protective efficiency of the apron was low, only 1.5% in scatter dose reduction on average. The apron at 0 cm from the beam lowered the dose by 7.5% at the phantom bottom but increased the dose by 2% at the top (backscatter) and did not affect the centre. When the apron was placed at 2.5 or 5 cm, the results were intermediate to the one obtained with the shielding at 0 cm and without shielding. The apron effectiveness is finally limited to the small fraction of external scattered radiation. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Shielding of the child's head during x-ray studies

International Nuclear Information System (INIS)

Tolmach, Eh.U.

1985-01-01

Three devices for X-ray shielding of child's head are suggested; the first one is a protective attachment for shielding a child being in horizontal position on an X-ray table; the second one is a protective stand for shielding head and body at roentgenofraphy of upper extremities of a child sitting near the X-ray table; the third one is a prot ctive suspension for shielding the head of a child being in vertical position

SHIELD 1.0: development of a shielding calculator program in diagnostic radiology

International Nuclear Information System (INIS)

Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da; Friedrich, Barbara Q.; Silva, Ana Maria Marques da

2013-01-01

In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

Status of the ITER tokamak nuclear shielding and radiological protection design

Energy Technology Data Exchange (ETDEWEB)

Leichtle, D., E-mail: dieter.leichtle@f4e.europa.eu [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Chaffard, P.Y.; Izquierdo, J. [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Juarez, R. [UNED, Juan del Rosal 12, Madrid 28040 (Spain); Pampin, R.; Portone, A. [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain)

2016-11-01

Highlights: • Comprehensive review of design status of the ITER tokamak regarding nuclear shielding. • Investigation of shield design options and streaming mitigation measures. • Review of state-of-the-art shutdown dose rate analyses for selected port systems. - Abstract: Nuclear shielding of the ITER tokamak encompasses several systems and interfaces in a complex radiation environment. Therefore any shielding design has to involve a series of structures, systems and components in an integrated approach. This is evident for the complex ex-vessel radiation environment with streaming and leakage of plasma neutrons and subsequent activation of ex-vessel structures which give raise to excessive shutdown dose rates in accessible areas of the cryostat. The paper reviews recent nuclear analyses related to the performance of primary shields and highlights challenges toward an integrated nuclear shielding design. The general need of propagation of shielding requirements is highlighted in the context of radiation cross talk due to penetrations. Radiation streaming through gaps and penetrations is a key problem in any efficient shield design. The impact on the evolving radiation environment due to several design options along streaming paths such as port gaps, as well as their modeling for nuclear analysis, is presented. Implications regarding design integration and compliance with integrated shielding requirements and ALARA dose are finally given.

The use and relevance of gonad protection shields in children during hips radiography

OpenAIRE

Silva, C. A.; Silva, P. N.; Ventura, Sandra Rua

2010-01-01

Considering that ionizing radiation effects are cumulative and the gonads are particularly sensitive to these effects, and also the clinical importance of pelvic radiographs in children, the excess of radiation exposure to the gonads must be avoided. The purpose of this study is to demonstrate the relevance of the correct use of gonad protection shields and to evaluate their use on the hip radiographs performed in a reference clinical institution, through the retrospective analysis of p...

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic.

Science.gov (United States)

Swadling, G F; Ross, J S; Datte, P; Moody, J; Divol, L; Jones, O; Landen, O

2016-11-01

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm -2 . This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

Bragg Curve, Biological Bragg Curve and Biological Issues in Space Radiation Protection with Shielding

Science.gov (United States)

Honglu, Wu; Cucinotta, F.A.; Durante, M.; Lin, Z.; Rusek, A.

2006-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. To achieve a Bragg curve distribution, we exposed cells to energetic heavy ions with the beam geometry parallel to a monolayer of fibroblasts. Qualitative analyses of gamma-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high linear energy transfer (LET) particle traversal of cells beyond the Bragg peak. A quantitative biological response curve generated for micronuclei (MN) induction across the Bragg curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono-to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results, along with other biological concerns, show that space radiation protection with shielding can be a complicated issue.

Gonad shielding in diagnostic radiology

International Nuclear Information System (INIS)

1975-06-01

The use of gonad shielding is an important radiation protection technique, intended to reduce unnecessary x-ray exposure of the gonads of patients from diagnostic x-ray procedures. This pamphlet will provide physicians and radiologic technologists with information which will aid their appropriate use of gonad shielding

Variation in ultrafiltered and LMW organic matter fluorescence properties under simulated estuarine mixing transects: 1. Mixing alone

Science.gov (United States)

Boyd, Thomas J.; Barham, Bethany P.; Hall, Gregory J.; Osburn, Christopher L.

2010-09-01

Ultrafiltered and low molecular weight dissolved organic matter (UDOM and LMW-DOM, respectively) fluorescence was studied under simulated estuarine mixing using samples collected from Delaware, Chesapeake, and San Francisco Bays (USA) transects. UDOM was concentrated by tangential flow ultrafiltration (TFF) from the marine (>33 PSU), mid-estuarine (˜16 PSU), and freshwater (ocean members. LMW fluorescence components fit a decreasing linear mixing model from mid salinities to the ocean end-member, but were more highly fluorescent than mixing alone would predict in lower salinities (shifts were also seen in UDOM peak emission wavelengths with blue-shifting toward the ocean end-member. Humic-type components in UDOM generally showed lower fluorescent intensities at low salinities, higher at mid-salinities, and lower again toward the ocean end-member. T (believed to be proteinaceous) and N (labile organic matter) peaks behaved similarly to each other, but not to B peak fluorescence, which showed virtually no variation in permeate or UDOM mixes with salinity. PCA and PARAFAC models showed similar results suggesting trends could be modeled for DOM end- and mid-member sources. Changes in fluorescence properties due to estuarine mixing may be important when using CDOM as a proxy for DOM cycling in coastal systems.

Gonad shielding in paediatric pelvic radiography: Effectiveness and practice

International Nuclear Information System (INIS)

Warlow, Thomas; Walker-Birch, Peter; Cosson, Philip

2014-01-01

The use of Gonad Shields (GS) has been advocated during pelvic radiography since the 1950's, particularly in children where the risks from radiation are higher. Previous literature reports that GS are often omitted and rarely used correctly. Objectives: Presentation of findings concerning use of GS in the context of previous data in the literature, and recommend any appropriate actions. Method: A retrospective analysis of images from an existing DICOM Digital Teaching Library (DTL) was conducted. Images of the pelvis from paediatric patients were reviewed and scored on whether a GS was present and (if present) whether the shield was considered to adequately protect the gonads. Results: 130 images were reviewed. 70 male and 60 female. The gonads were deemed to be protected by a shield in 22 images (17%), inadequately protected when a shield was used in 44 images (34%) with the remaining 64 images (49%) having no shield at all. A lack of adequate protection for the gonads was found, with females more likely to be inadequately protected than males (χ 2  = 19.009, df = 1, p < 0.001). These findings become more clinically significant when reports of ovaries lying outside of the pelvic basin (in paediatric patients) are considered. Conclusions: The current practice of gonad shielding is neither effective nor beneficial for female paediatric patients, incorrect shield placement can often require repeat exposures. This finding is commensurate with previous literature. Therefore, gonad shielding is no longer an appropriate optimization tool for female paediatric patients during conventional radiography of the pelvis, and should be abandoned

Mechanism study of endothelial protection and inhibits platelet activation of low molecular weight fucoidan from Laminaria japonica

Science.gov (United States)

Chen, Anjin; Zhang, Fang; Shi, Jie; Zhao, Xue; Yan, Meixing

2016-10-01

Several studies have indicated that fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica could inhibit the activation of platelets directly by reducing the platelet aggregation. To explore the direct effect of LMW fucoidan on the platelet system furthermore and examine the possible mechanism, the endothelial protection and inhibits platelet activation effects of two LMW fucoidan were investigated. In the present study, Endothelial injury model of rats was made by injection of adrenaline (0.4 mg kg-1) and human umbilical vein endothelial cells were cultured. vWF level was be investigated in vivo and in vitro as an important index of endothelial injury. LMW fucoidan could significantly reduce vWF level in vascular endothelial injury rats and also significantly reduce vWF level in vitro. The number of EMPs was be detected as another important index of endothelial injury. The results showed that LMW fucoidan reduced EMPs stimulated by tumor necrosis factor. In this study, it was found that by inhibiting platelet adhesion, LMW fucoidan played a role in anti-thrombosis and the specific mechanism of action is to inhibit the flow of extracellular Ca2+. All in a word, LMW fucoidan could inhibit the activation of platelets indirectly by reducing the concentration of EMPs and vWF, at the same time; LMW fucoidan inhibited the activation of platelets directly by inhibiting the flow of extracellular Ca2+.

Active shield technology for space craft protection revisited in new laboratory results and analysis

Science.gov (United States)

Bamford, R.; Gibson, K. J.; Thornton, A. T.; Bradford, J.; Bingham, R.; Gargate, L.; Silva, L. O.; Fonseca, R. A.; Hapgood, M.; Norberg, C.; Todd, T.; Stamper, R.

2009-04-01

Energetic ions in the solar wind plasma are a known hazard to both spacecraft electronics and to astronaut's health. Of primary concern is the exposure to keV--MeV protons on manned space flights to the Moon and Mars that extend over long periods of time. Attempts to protect the spacecraft include active shields that are reminiscent of Star Trek "deflector" shields. Here we describe a new experiment to test the shielding concept of a dipole-like magnetic field and plasma, surrounding the spacecraft forming a "mini magnetosphere". Initial laboratory experiments have been conducted to determine the effectiveness of a magnetized plasma barrier to be able to expel an impacting, low beta, supersonic flowing energetic plasma representing the Solar Wind. Optical and Langmuir probe data of the plasma density, the plasma flow velocity, and the intensity of the dipole field clearly show the creation of a narrow transport barrier region and diamagnetic cavity virtually devoid of energetic plasma particles. This demonstrates the potential viability of being able to create a small "hole" in a Solar Wind plasma, of the order of the ion Larmor orbit width, in which an inhabited spacecraft could reside in relative safety. The experimental results have been quantitatively compared to a 3D particle-in-cell ‘hybrid' code simulation that uses kinetic ions and fluid electrons, showing good qualitative agreement and excellent quantitative agreement. Together the results demonstrate the pivotal role of particle kinetics in determining generic plasma transport barriers. [1] [1] R Bamford et al., "The interaction of a flowing plasma with a dipole magnetic field: measurements and modelling of a diamagnetic cavity relevant to spacecraft protection." 2008 Plasma Phys. Control. Fusion 50 124025 (11pp) doi: 10.1088/0741-3335/50/12/124025

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

Energy Technology Data Exchange (ETDEWEB)

Swadling, G. F.; Ross, J. S.; Datte, P.; Moody, J.; Divol, L.; Jones, O.; Landen, O. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2016-11-15

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

Safety shield for vacuum/pressure-chamber windows

Science.gov (United States)

Shimansky, R. A.; Spencer, R.

1980-01-01

Optically-clear shatter-resistant safety shield protects workers from implosion and explosion of vacuum and pressure windows. Plastic shield is inexpensive and may be added to vacuum chambers, pressure chambers, and gas-filling systems.

Radiation shielding application of lead glass

International Nuclear Information System (INIS)

Nathuram, R.

2017-01-01

Nuclear medicine and radiotherapy centers equipped with high intensity X-ray or teletherapy sources use lead glasses as viewing windows to protect personal from radiation exposure. Lead is the main component of glass which is responsible for shielding against photons. It is therefore essential to check the shielding efficiency before they are put in use. This can be done by studying photon transmission through the lead glasses. The study of photon transmission in shielding materials has been an important subject in medical physics and is potential useful in the development of radiation shielding materials

Thick Galactic Cosmic Radiation Shielding Using Atmospheric Data

Science.gov (United States)

Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Koontz, Steven L.

2013-01-01

NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g!cm2 in thickness and have predicted that shields of this thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the earth's atmosphere, a very thick shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.

Shielding of Medical Radiation Facilities - National Council on Radiation Protection and Measurements Reports No. 147 and No. 151

International Nuclear Information System (INIS)

KASE, K.R.

2008-01-01

The National Council on Radiation Protection and Measurements of the United States (NCRP) has issued two reports in the past 18 months that provide methods and data for designing shielding for diagnostic radiological imaging and radiation therapy facilities. These reports update previous publications on this subject with revised methods that take into account new technologies, results from measurements and new data that have been published in the last 30 years. This paper gives a brief summary of the contents of these reports, the methods recommended for determining the shielding required and the data provided to aid in the calculations

Radiation shielding performance of some concrete

International Nuclear Information System (INIS)

Akkurt, I.; Akyildirim, H.; Mavi, B.; Kilincarslan, S.; Basyigit, C.

2007-01-01

The energy consumption is increasing with the increased population of the world and thus new energy sources were discovered such as nuclear energy. Besides using nuclear energy, nuclear techniques are being used in a variety of fields such as medical hospital, industry, agriculture or military issue, the radiation protection becomes one of the important research fields. In radiation protection, the main rules are time, distance and shielding. The most effective radiation shields are materials which have a high density and high atomic number such as lead, tungsten which are expensive. Alternatively the concrete which produced using different aggregate can be used. The effectiveness of radiation shielding is frequently described in terms of the half value layer (HVL) or the tenth value layer (TVL). These are the thicknesses of an absorber that will reduce the radiation to half, and one tenth of its intensity respectively. In this study the radiation protection properties of different types of concrete will be discussed

A New Microwave Shield Preparation for Super High Frequency Range: Occupational Approach to Radiation Protection.

Science.gov (United States)

Zaroushani, Vida; Khavanin, Ali; Jonidi Jafari, Ahmad; Mortazavi, Seyed Bagher

2016-01-01

Widespread use of X-band frequency (a part of the super high frequency microwave) in the various workplaces would contribute to occupational exposure with potential of adverse health effects.  According to limited study on microwave shielding for the workplace, this study tried to prepare a new microwave shielding for this purpose. We used EI-403 epoxy thermosetting resin as a matrix and nickel oxide nanoparticle with the diameter of 15-35 nm as filler. The Epoxy/ Nickel oxide composites with 5, 7, 9 and 11 wt% were made in three different thicknesses (2, 4 and 6 mm). According to transmission / reflection method, shielding effectiveness (SE) in the X-band frequency range (8-12.5 GHz) was measured by scattering parameters directly given by the 2-port Vector Network Analyzer. The fabricated composites characterized by X-ray Diffraction and Field Emission Scanning Electron Microscope. The best average of shielding effectiveness in each thickness of fabricated composites obtained by 11%-2 mm, 7%-4 mm and 7%-6 mm composites with SE values of 46.80%, 66.72% and 64.52%, respectively. In addition, the 11%-6 mm, 5%-6 mm and 11%-4 mm-fabricated composites were able to attenuate extremely the incident microwave energy at 8.01, 8.51 and 8.53 GHz by SE of 84.14%, 83.57 and 81.30%, respectively. The 7%-4mm composite could be introduced as a suitable alternative microwave shield in radiation protection topics in order to its proper SE and other preferable properties such as low cost and weight, resistance to corrosion etc. It is necessary to develop and investigate the efficacy of the fabricated composites in the fields by future studies.

Shielding synchrotron light sources: Advantages of circular shield walls tunnels

Energy Technology Data Exchange (ETDEWEB)

Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2016-08-11

Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

Concrete radiation shielding

International Nuclear Information System (INIS)

Kaplan, M.F.

1989-01-01

The increased use of nuclear energy has given rise to a growth in the amount of artificially produced radiation and radioactive materials. The design and construction of shielding to protect people, equipment and structures from the effects of radiation has never been more important. Experience has shown that concrete is an effective, versatile and economical material for the construction of radiation shielding. This book provides information on the principles governing the interaction of radiation with matter and on relevant nuclear physics to give the engineer an understanding of the design and construction of concrete shielding. It covers the physical, mechanical and nuclear properties of concrete; the effects of elevated temperatures and possible damage to concrete due to radiation; basic procedures for the design of concrete radiation shields and finally the special problems associated with their construction and cost. Although written primarily for engineers concerned with the design and construction of concrete shielding, the book also reviews the widely scattered data and information available on this subject and should therefore be of interest to students and those wishing to research further in this field. (author)

Radiation shielding in dental radiography

International Nuclear Information System (INIS)

Stenstroem, B.; Rehnmark-Larsson, S.; Julin, P.; Richter, S.

1983-01-01

The protective effect in the thyroid region from different types of radiation shieldings at intraoral radiography has been studied as well as the reduction of the absorbed dose to the sternal and the gonadal regions. The shieldings tested were five different types of leaded aprons, of which three had an attached leaded collar and the other two were used in combination with separate soft leaded collars. Furthermore one of the soft leaded collars and an unflexible horizontal leaded shield were tested separately. Two dental x-ray machines of 60 and 65 kVp with rectangular and circular tube collimators were used. The exposure time corresponded to speed group E film. The absorbed doses were measured with two ionization chambers. No significant difference in the protective effect in the thyroid gland could be found between the different types of radiation shieldings. There was a dose reduction by approximately a factor of 2 to the thyroid region down to 0.08 mGy per full survey using parallelling technique, and below 0.001 mGy per single bitewing exposure. The shieldings reduced the thyroid dose using bisecting-angle technique by a factor of 5 down to 0.15 mGy per full survey (20 exposures). In the sternal region the combinations of apron and collar reduced the absorbed dose from a full survey to below 2 μGy compared with 18 μGy (parallelling) and 31 μGy (biscting-angle) without any shielding. With the horizontal leaded shield a reduction by a factor of 6 was obtained but no significant sternal dose reduction could be detected from the soft collar alone. The gonadal dose could be reduced by a factor of 10 with the horizontal leaded shield, parallelling technique and circular collimator. Using leaded aprons the gonadal dose was approximately one per cent of the dose without any shielding, i.e. below 0.01 μGy per single intraoral exposure. (Authors)

SHIELD 1.0: development of a shielding calculator program in diagnostic radiology; SHIELD 1.0: desenvolvimento de um programa de calculo de blindagem em radiodiagnostico

Energy Technology Data Exchange (ETDEWEB)

Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da [Hospital Sao Lucas (PUCRS), Porto Alegre, RS (Brazil); Friedrich, Barbara Q.; Silva, Ana Maria Marques da, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

2013-08-15

In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

Foam-Reinforced Polymer Matrix Composite Radiation Shields, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — New and innovative lightweight radiation shielding materials are needed to protect humans in future manned exploration vehicles. Radiation shielding materials are...

Alignment modification for pencil eye shields

International Nuclear Information System (INIS)

Evans, M.D.; Pla, M.; Podgorsak, E.B.

1989-01-01

Accurate alignment of pencil beam eye shields to protect the lens of the eye may be made easier by means of a simple modification of existing apparatus. This involves drilling a small hole through the center of the shield to isolate the rayline directed to the lens and fabricating a suitable plug for this hole

Penetration shielding applications of CYLSEC

International Nuclear Information System (INIS)

Dexheimer, D.T.; Hathaway, J.M.

1985-01-01

Evaluation of penetration and discontinuity shielding is necessary to meet 10CFR20 regulations for ensuring personnel exposures are as low as reasonably achievable (ALARA). Historically, those shielding evaluations have been done to some degree on all projects. However, many early plants used conservative methods due to lack of an economical computer code, resulting in costly penetration shielding programs. With the increased industry interest in cost effectively reducing personnel exposures to meet ALARA regulations and with the development of the CYLSEC gamma transport computer code at Bechtel, a comprehensive effort was initiated to reduce penetration and discontinuity shielding but still provide a prudent degree of protection for plant personnel from radiation streaming. This effort was more comprehensive than previous programs due to advances in shielding analysis technology and increased interest in controlling project costs while maintaining personnel exposures ALARA. Methodology and resulting cost savings are discussed

Shield calculations, optimization vs. paradigm

International Nuclear Information System (INIS)

Cornejo D, N.; Hernandez S, A.; Martinez G, A.

2006-01-01

Many shieldings have been designed under the criteria of 'Maximum dose rates of project'. It has created the paradigm of those 'low dose rates', for the one which not few specialists would consider unacceptable levels of dose rate superior to the units of μSv.h -1 , independently of the exposure times. At the present time numerous shieldings are being designed considering dose restrictions in real times of exposure. After these new shieldings, the dose rates could be notably superior to those after traditional shieldings, without it implies inadequate designs or constructive errors. In the work significant differences in levels of dose rates and thickness of shieldings estimated by both methods for some typical facilities. It was concluded that the use of real times of exposure is more adequate for the optimization of the Radiological Protection, although this method demands bigger care in its application. (Author)

Experimental and simulation optimization analysis of the Whipple shields against shaped charge

Science.gov (United States)

Hussain, G.; Hameed, A.; Horsfall, I.; Barton, P.; Malik, A. Q.

2012-06-01

Occasionally, the Whipple shields are used for the protection of a space station and a satellite against the meteoroids and orbital debris. In the Whipple shields each layer of the shield depletes part of high speed projectile energy either by breaking the projectile or absorbing its energy. Similarly, this investigation uses the Whipple shields against the shaped charge to protect the light armour such as infantry fighting vehicles with a little modification in their design. The unsteady multiple interactions of shaped charge jet with the Whipple shield package against the steady homogeneous target is scrutinized to optimize the shield thickness. Simulations indicate that the shield thickness of 0.75 mm offers an optimum configuration against the shaped charge. Experiments also support this evidence.

Measuring space radiation shielding effectiveness

Directory of Open Access Journals (Sweden)

Bahadori Amir

2017-01-01

Full Text Available Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles is described. Using accelerated alpha particles at the National Aeronautics and Space Administration Space Radiation Laboratory at Brookhaven National Laboratory, the method is applied to sample tiles from the Heat Melt Compactor, which were created by melting material from a simulated astronaut waste stream, consisting of materials such as trash and unconsumed food. The shielding effectiveness calculated from measurements of the Heat Melt Compactor sample tiles is about 10% less than the shielding effectiveness of polyethylene. Shielding material produced from the astronaut waste stream in the form of Heat Melt Compactor tiles is therefore found to be an attractive solution for protection against space radiation.

Measuring space radiation shielding effectiveness

Science.gov (United States)

Bahadori, Amir; Semones, Edward; Ewert, Michael; Broyan, James; Walker, Steven

2017-09-01

Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles is described. Using accelerated alpha particles at the National Aeronautics and Space Administration Space Radiation Laboratory at Brookhaven National Laboratory, the method is applied to sample tiles from the Heat Melt Compactor, which were created by melting material from a simulated astronaut waste stream, consisting of materials such as trash and unconsumed food. The shielding effectiveness calculated from measurements of the Heat Melt Compactor sample tiles is about 10% less than the shielding effectiveness of polyethylene. Shielding material produced from the astronaut waste stream in the form of Heat Melt Compactor tiles is therefore found to be an attractive solution for protection against space radiation.

Practical radiation shielding for biomedical research

International Nuclear Information System (INIS)

Klein, R.C.; Reginatto, M.; Party, E.; Gershey, E.L.

1990-01-01

This paper reports on calculations which exist for estimating shielding required for radioactivity; however, they are often not applicable for the radionuclides and activities common in biomedical research. A variety of commercially available Lucite shields are being marketed to the biomedical community. Their advertisements may lead laboratory workers to expect better radiation protection than these shields can provide or to assume erroneously that very weak beta emitters require extensive shielding. The authors have conducted a series of shielding experiments designed to simulate exposures from the amounts of 32 P, 51 Cr and 125 I typically used in biomedical laboratories. For most routine work, ≥0.64 cm of Lucite covered with various thicknesses of lead will reduce whole-body occupational exposure rates of < 1mR/hr at the point of contact

A Protective Eye Shield for Prevention of Media Opacities during Small Animal Ocular Imaging

Science.gov (United States)

Bell, Brent A.; Kaul, Charles; Hollyfield, Joe G.

2014-01-01

Optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO) and other non-invasive imaging techniques are increasingly used in eye research to document disease-related changes in rodent eyes. Corneal dehydration is a major contributor to the formation of ocular opacities that can limit the repeated application of these techniques to individual animals. General anesthesia is usually required for imaging, which is accompanied by the loss of the blink reflex. As a consequence, the tear film cannot be maintained, drying occurs and the cornea becomes dehydrated. Without supplemental hydration, structural damage to the cornea quickly follows. Soon thereafter, anterior lens opacities can also develop. Collectively these changes ultimately compromise image quality, especially for studies involving repeated use of the same animal over several weeks or months. To minimize these changes, a protective shield was designed for mice and rats that prevent ocular dehydration during anesthesia. The eye shield, along with a semi-viscous ophthalmic solution, is placed over the corneas as soon as the anesthesia immobilizes the animal. Eye shields are removed for only the brief periods required for imaging and then reapplied before the fellow eye is examined. As a result, the corneal surface of each eye is exposed only for the time required for imaging. The device and detailed methods described here minimize the corneal and lens changes associated with ocular surface desiccation. When these methods are used consistently, high quality images can be obtained repeatedly from individual animals. PMID:25245081

Radiation shielding lead shield

International Nuclear Information System (INIS)

Dei, Shoichi.

1991-01-01

The present invention concerns lead shields for radiation shielding. Shield boxes are disposed so as to surround a pipeline through which radioactive liquids, mists or like other objects are passed. Flanges are formed to each of the end edges of the shield boxes and the shield boxes are connected to each other by the flanges. Upon installation, empty shield boxes not charged with lead particles and iron plate shields are secured at first at the periphery of the pipeline. Then, lead particles are charged into the shield boxes. This attains a state as if lead plate corresponding to the depth of the box is disposed. Accordingly, operations for installation, dismantling and restoration can be conducted in an empty state with reduced weight to facilitate the operations. (I.S.)

MFTF-α + T shield design

International Nuclear Information System (INIS)

Gohar, Y.

1985-01-01

MFTF-α+T is a DT upgrade option of the Tandem Mirror Fusion Test Facility (MFTF-B) to study better plasma performance, and test tritium breeding blankets in an actual fusion reactor environment. The central cell insert, designated DT axicell, has a 2-MW/m 2 neutron wall loading at the first wall for blanket testing. This upgrade is completely shielded to protect the reactor components, the workers, and the general public from the radiation environment during operation and after shutdown. The shield design for this upgrade is the subject of this paper including the design criteria and the tradeoff studies to reduce the shield cost

Efficiency of the cervical lead shield during intraoral radiography

International Nuclear Information System (INIS)

Kaffe, I.; Littner, M.M.; Shlezinger, T.; Segal, P.

1986-01-01

The cervical lead shield was compared with the conventional lead apron with regard to efficiency of protection against radiation during a full-month survey (fourteen periapical and two bitewing radiographs). The study was performed on a Temex tissue-equivalent human phantom, and thermoluminescent dosimetry was used to measure radiation absorption in the ovaries, testes, and thyroid gland areas. Results showed that the cervical shield significantly reduces the amount of radiation to the skin in all three areas and is equally as effective as the combination of lead apron and thyroid shield. It is therefore recommended as a protective measure during intraoral radiography

Radiation Shielding Properties of Some Marbles in Turkey

International Nuclear Information System (INIS)

Guenoglu, K.; Akkurt, I.

2011-01-01

Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazardous effect of radiation into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined.In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.

Radiation Shielding Properties of Some Marbles in Turkey

Science.gov (United States)

Günoǧlu, K.; Akkurt, I.

2011-12-01

Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazordous effect of radition into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined. In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.

A history of radiation shielding of x-ray therapy rooms

International Nuclear Information System (INIS)

McGinley, P.H.; Miner, M.S.

1996-01-01

In this report the history of shielding for radiation treatment rooms is traced from the time of the discovery of x rays to the present. During the early part of the twentieth century the hazards from ionizing radiation were recognized and the use of lead and other materials became common place for shielding against x rays. Techniques for the calculation of the shield thickness needed for x ray protection were developed in the 1920's, and shielding materials were characterized in terms of the half value layer or simple exponential factors. At the same time, better knowledge of the interaction between radiation and matter was acquired. With the development of high energy medical accelerators after 1940, new and more complex shielding problems had to be addressed. Recently, shielding requirements have become more stringent as standards for exposure of personnel and the general public have been reduced. The art of shielding of radiation treatment facilities is still being developed, and the need for a revision of the reports on shielding of medical accelerators from the National Council on Radiation Protection and Measurements is emphasized in this article. (author). 61 Refs., 3 Tabs

Shielding calculations. Optimization vs. Paradigms

International Nuclear Information System (INIS)

Cornejo Diaz, Nestor; Hernandez Saiz, Alejandro; Martinez Gonzalez, Alina

2005-01-01

Many radiation shielding barriers in Cuba have been designed according to the criterion of Maxi-mum Projected Dose Rates. This fact has created the paradigm of low dose rates. Because of this, dose rate levels greater than units of Sv.h-1 would be considered unacceptable by many specialists, regardless of the real exposure times. Nowadays many shielding barriers are being designed using dose constraints in real exposure times. Behind the new barriers, dose rates could be notably greater than those behind the traditional ones, and it does not imply inadequate designs or constructive errors. In this work were obtained significant differences in dose rate levels and shield-ing thicknesses calculated by both methods for some typical installations. The work concludes that real exposure time approach is more adequate in order to optimise Radiation Protection, although this method should be carefully applied

HPGe detector shielding adjustment

International Nuclear Information System (INIS)

Trnkova, L.; Rulik, P.

2008-01-01

Low-level background shielding of HPGe detectors is used mainly for environmental samples with very low content of radionuclides. National Radiation Protection Institute (SURO) in Prague is equipped with 14 HPGe detectors with relative efficiency up to 150%. The detectors are placed in a room built from materials with low content of natural radionuclides and equipped with a double isolation of the floor against radon. Detectors themselves are placed in lead or steel shielding. Steel shielding with one of these detectors with relative efficiency of 100% was chosen to be rebuilt to achieve lower minimum detectable activity (MDA). Additional lead and copper shielding was built up inside the original steel shielding to reduce the volume of the inner space and filled with nitrogen by means of evaporating liquid nitrogen. The additional lead and copper shielding, consequent reduction of the inner volume and supply of evaporated nitrogen, caused a decrease of the background count and accordingly MDA values as well. The effect of nitrogen evaporation on the net areas of peaks belonging to radon daughters is significant. The enhanced shielding adjustment has the biggest influence in low energy range, what can be seen in collected data. MDA values in energy range from 30 keV to 400 keV decreased to 0.65-0.85 of original value, in energy range from 400 keV to 2 MeV they fell to 0.70-0.97 of original value. (authors)

SU-F-I-72: Evaluation of the Ancillary Lead Shielding for Optimizing Radiation Protection in the Interventional Radiology Department

Energy Technology Data Exchange (ETDEWEB)

Tonkopi, E; Lightfoot, C [Dalhousie University, Queen Elizabeth II Health Sciences Ctr, Halifax, NS (Canada); LeBlanc, E [Queen Elizabeth II Health Sciences Ctr, Halifax, NS (Canada)

2016-06-15

Purpose: The rising complexity of interventional fluoroscopic procedures has resulted in an increase of occupational radiation exposures in the interventional radiology (IR) department. This study assessed the impact of ancillary shielding on optimizing radiation protection for the IR staff. Methods: Scattered radiation measurements were performed in two IR suites equipped with Axiom Artis systems (Siemens Healthcare, Erlangen, Germany) installed in 2006 and 2010. Both rooms had suspended ceiling-mounted lead-acrylic shields of 75×60 cm (Mavig, Munich, Germany) with lead equivalency of 0.5 mm, and under-table drapes of 70×116 cm and 65×70 cm in the newer and the older room respectively. The larger skirt can be wrapped around the table’s corner and in addition the newer suite had two upper shields of 25×55 cm and 25×35 cm. The patient was simulated by 30 cm of acrylic, air kerma rate (AKR) was measured with the 180cc ionization chamber (AccuPro Radcal Corporation, Monrovia, CA, USA) at different positions. The ancillary shields, x-ray tube, image detector, and table height were adjusted by the IR radiologist to simulate various clinical setups. The same exposure parameters were used for all acquisitions. AKR measurements were made at different positions relative to the operator. Results: The AKR measurements demonstrated 91–99% x-ray attenuation by the drapes in both suites. The smaller size of the under-table skirt and absence of the side-drapes in the older room resulted in a 20–50 fold increase of scattered radiation to the operator. The mobile suspended lead-acrylic shield reduced AKR by 90–94% measured at 150–170 cm height. The recommendations were made to replace the smaller under-table skirt and to use the ceiling-mounted shields for all IR procedures. Conclusion: The ancillary shielding may significantly affect radiation exposure to the IR staff. The use of suspended ceiling-mounted shields is especially important for reduction of

Development of radiation shielding standards in the American Nuclear Society

International Nuclear Information System (INIS)

Trubey, D.K.

1975-11-01

The American Nuclear Society (ANS) is a standards-writing organization-member of the American National Standards Institute (ANSI). The ANS Standards Committee has a subcommittee denoted ANS-6, Shielding, whose charge is to establish standards in connection with radiation protection and shielding, to provide shielding information to other standards writing groups, and to prepare recommended sets of shielding data and test problems. This paper is a progress report of this subcommittee

Shielding effects of concrete and foam external pipeline coatings

International Nuclear Information System (INIS)

Barlo, T.J.; Werner, D.P.

1992-01-01

The research project began in July, 1986 and was completed in December, 1990. The objectives of the research were: To determine whether concrete and urethane foam-barrier coatings shield the pipe from cathodic-protection current, To determine whether the barrier coatings also effectively shield the pipe from the environment, thus reducing the need for cathodic protection, To determine what levels of cathodic protection will be required to overcome shielding, and To establish what types of barrier coatings are most compatible with obtaining adequate levels of cathodic protection. To achieve these objectives, laboratory experiments were conducted with five barrier coating materials. These materials were (1) 2-lb/ft 3 , closed-cell urethane foam, (2) 3-lb/ft 3 , closed-cell urethane foam, (3) concrete barrier material, (4) glass fiber-reinforced concrete barrier material, and (5) sand. The barrier materials, whole and intentionally cracked, were applied to the bare, FBE-coated, and tape-coated steel specimens. The specimens were tested in aqueous electrolytes at room temperature and 140 degree F with no protection, protection to -0.95 V, and overprotection to -1.2 V (Cu/CuSO 4 )

Transparent Metal-Salt-Filled Polymeric Radiation Shields

Science.gov (United States)

Edwards, David; Lennhoff, John; Harris, George

2003-01-01

"COR-RA" (colorless atomic oxygen resistant -- radiation shield) is the name of a transparent polymeric material filled with x-ray-absorbing salts of lead, bismuth, cesium, and thorium. COR-RA is suitable for use in shielding personnel against bremsstrahlung radiation from electron-beam welding and industrial and medical x-ray equipment. In comparison with lead-foil and leaded-glass shields that give equivalent protection against x-rays (see table), COR-RA shields are mechanically more durable. COR-RA absorbs not only x-rays but also neutrons and rays without adverse effects on optical or mechanical performance. The formulation of COR-RA with the most favorable mechanical-durability and optical properties contains 22 weight percent of bismuth to absorb x-rays, plus 45 atomic percent hydrogen for shielding against neutrons.

FLUKA shielding calculations for the FAIR project

International Nuclear Information System (INIS)

Fehrenbacher, Georg; Kozlova, Ekaterina; Radon, Torsten; Sokolov, Alexey

2015-01-01

FAIR is an international accelerator project being in construction at GSI Helmholtz center for heavy ion research in Darmstadt. The Monte Carlo program FLUKA is used to study radiation protection problems. The contribution deals with general application possibilities of FLUKA and for FAIR with respect the radiation protection planning. The necessity to simulate the radiation transport through shielding of several meters thickness and to determine the equivalent doses outside the shielding with sufficient accuracy is demonstrated using two examples under consideration of the variance reduction. Results of simulation calculations for activation estimation in accelerator facilities are presented.

MEANS FOR SHIELDING AND COOLING REACTORS

Science.gov (United States)

Wigner, E.P.; Ohlinger, L.A.; Young, G.J.; Weinberg, A.M.

1959-02-10

Reactors of the water-cooled type and a means for shielding such a rcactor to protect operating personnel from harmful radiation are discussed. In this reactor coolant tubes which contain the fissionable material extend vertically through a mass of moderator. Liquid coolant enters through the bottom of the coolant tubes and passes upwardly over the fissionable material. A shield tank is disposed over the top of the reactor and communicates through its bottom with the upper end of the coolant tubes. A hydrocarbon shielding fluid floats on the coolant within the shield tank. With this arrangements the upper face of the reactor can be opened to the atmosphere through the two superimposed liquid layers. A principal feature of the invention is that in the event radioactive fission products enter thc coolant stream. imposed layer of hydrocarbon reduces the intense radioactivity introduced into the layer over the reactors and permits removal of the offending fuel material by personnel shielded by the uncontaminated hydrocarbon layer.

Shielding walls against ionizing radiation

International Nuclear Information System (INIS)

1993-05-01

Hot-cell shielding walls consist of building blocks made of lead according to DIN 25407 part 1, and of special elements according to DIN 25407 part 2. Alpha-gamma cells can be built using elements for protective contamination boxes according to DIN 25480 part 1. This standards document intends to provide planning engineers, manufacturers, future users and the competent authorities and experts with a basis for the design of hot cells with lead shielding walls and the design of hot-cell equipment. (orig./HP) [de

The use of gonad shielding in paediatric hip and pelvis radiographs.

Science.gov (United States)

Fawcett, S L; Barter, S J

2009-05-01

The problem of inaccurate placement of gonad shields in children has been highlighted by several publications nationally and internationally over the past decade and more. Here, we review the literature and present the results of a regional audit designed to assess the use and accuracy of placement of gonad shields for hip and pelvis radiographs in children. 100 consecutive anteroposterior hip or pelvis radiographs in patients under the age of 16 years were reviewed in each of 9 centres. We also included the most recent and all previously available relevant radiographs. A total of 2405 radiographs were reviewed with regard to the presence of a shield and to the accuracy of any shield placement with respect to gonad protection and visualization of orthopaedic landmarks. It is recommended that gonad shields are used in all follow-up paediatric pelvis radiographs. Our results show they were only used in 70% of such cases. When placed, only 38% of all shields were considered to be positioned accurately. For cases where shielding was indicated, an accurately placed shield was present in just 26% of radiographs. Formal written departmental guidelines for shield use were only available in two centres. We conclude that clear guidelines need to be formulated which, together with shield redesign, improved training and audit, should increase effective gonad protection for children.

Radiation shielding

International Nuclear Information System (INIS)

Yue, D.D.

1979-01-01

Details are given of a cylindrical electric penetration assembly for carrying instrumentation leads, used in monitoring the performance of a nuclear reactor, through the containment wall of the reactor. Effective yet economical shielding protection against both fast neutron and high-energy gamma radiation is provided. Adequate spacing within the assembly allows excessive heat to be efficiently dissipated and means of monitoring all potential radiation and gas leakage paths are provided. (UK)

Shielding during x-ray examination of pediatric female patients with developmental dysplasia of the hip

International Nuclear Information System (INIS)

Tsai, Yi-Shan; Liu, Yi-Sheng; Chuang, Ming-Tsung; Wang, Chien-Kuo; Lai, Cheng-Shih; Tsai, Hong-Ming; Lu, Chia-Hsing; Lin, Chii-Jeng

2014-01-01

Patients with developmental dysplasia of the hip (DDH) generally undergo multiple x-ray examinations of both hip joints. During these examinations, the gonads are completely exposed to radiation, unless shielded. Although many types and sizes of gonad shields exist, they often do not provide adequate protection because of size and placement issues; additionally, these shields are frequently omitted for female patients. Our aim was to assess gonad protection during x-ray examination that is provided by gonad shields designed for individual female patients with DDH. We retrospectively retrieved data from the Picture Archiving and Communication System database; pelvic plain x-ray films from 766 females, 18 years old or younger, were included in our analysis. Based on x-ray measurements of the anterior superior iliac spine, we developed a system of gonad shield design that depended on the distance between anterior superior iliac spine markers. We custom-made shields and then examined shielding rates and shielding accuracy before and after these new shields became available. Standard (general-purpose) shields were used before our custom design project was implemented. The shielding rate and shielding accuracy were, respectively, 14.5% and 8.4% before the project was implemented and 72.7% and 32.2% after it was implemented. A shield that is more anatomically correct and available in several different sizes may increase the likelihood of gonad protection during pelvic x-ray examinations. (paper)

Shielding during x-ray examination of pediatric female patients with developmental dysplasia of the hip.

Science.gov (United States)

Tsai, Yi-Shan; Liu, Yi-Sheng; Chuang, Ming-Tsung; Wang, Chien-Kuo; Lai, Cheng-Shih; Tsai, Hong-Ming; Lin, Chii-Jeng; Lu, Chia-Hsing

2014-12-01

Patients with developmental dysplasia of the hip (DDH) generally undergo multiple x-ray examinations of both hip joints. During these examinations, the gonads are completely exposed to radiation, unless shielded. Although many types and sizes of gonad shields exist, they often do not provide adequate protection because of size and placement issues; additionally, these shields are frequently omitted for female patients. Our aim was to assess gonad protection during x-ray examination that is provided by gonad shields designed for individual female patients with DDH.We retrospectively retrieved data from the Picture Archiving and Communication System database; pelvic plain x-ray films from 766 females, 18 years old or younger, were included in our analysis. Based on x-ray measurements of the anterior superior iliac spine, we developed a system of gonad shield design that depended on the distance between anterior superior iliac spine markers. We custom-made shields and then examined shielding rates and shielding accuracy before and after these new shields became available. Standard (general-purpose) shields were used before our custom design project was implemented. The shielding rate and shielding accuracy were, respectively, 14.5% and 8.4% before the project was implemented and 72.7% and 32.2% after it was implemented. A shield that is more anatomically correct and available in several different sizes may increase the likelihood of gonad protection during pelvic x-ray examinations.

Design of radiation shields in nuclear reactor core

International Nuclear Information System (INIS)

Mousavi Shirazi, A.; Daneshvar, Sh.; Aghanajafi, C.; Jahanfarnia, Gh.; Rahgoshay, M.

2008-01-01

This article consists of designing radiation shields in the core of nuclear reactors to control and restrain the harmful nuclear radiations in the nuclear reactor cores. The radiation shields protect the loss of energy. caused by nuclear radiation in a nuclear reactor core and consequently, they cause to increase the efficiency of the reactor and decrease the risk of being under harmful radiations for the staff. In order to design these shields, by making advantages of the O ppenheim Electrical Network m ethod, the structure of the shields are physically simulated and by obtaining a special algorithm, the amount of optimized energy caused by nuclear radiations, is calculated

Dosimetric evaluation of lead and tungsten eye shields in electron beam treatment

International Nuclear Information System (INIS)

Shiu, Almon S.; Tung, Samuel S.; Gastorf, Robert J.; Hogstrom, Kenneth R.; Morrison, William H.; Peters, Lester J.

1996-01-01

Purpose: The purpose of this study is to report that commercially available eye shields (designed for orthovoltage x-rays) are inadequate to protect the ocular structures from penetrating electrons for electron beam energies equal to or greater than 6 MeV. Therefore, a prototype medium size tungsten eye shield was designed and fabricated. The advantages of the tungsten eye shield over lead are discussed. Methods and Materials: Electron beams (6-9 MeV) are often used to irradiate eyelid tumors to curative doses. Eye shields can be placed under the eyelids to protect the globe. Film and thermoluminescent dosimeters (TLDs) were used within a specially constructed polystyrene eye phantom to determine the effectiveness of various commercially available internal eye shields (designed for orthovoltage x-rays). The same procedures were used to evaluate a prototype medium size tungsten eye shield (2.8 mm thick), which was designed and fabricated for protection of the globe from penetrating electrons for electron beam energy equal to 9 MeV. A mini-TLD was used to measure the dose enhancement due to electrons backscattered off the tungsten eye shield, both with or without a dental acrylic coating that is required to reduce discomfort, permit sterilization of the shield, and reduce the dose contribution from backscattered electrons. Results: Transmission of a 6 MeV electron beam through a 1.7 mm thick lead eye shield was found to be 50% on the surface (cornea) of the phantom and 27% at a depth of 6 mm (lens). The thickness of lead required to stop 6-9 MeV electron beams is impractical. In place of lead, a prototype medium size tungsten eye shield was made. For 6 to 9 MeV electrons, the doses measured on the surface (cornea) and at 6 mm (lens) and 21 mm (retina) depths were all less than 5% of the maximum dose of the open field (4 x 4 cm). Electrons backscattered off a tungsten eye shield without acrylic coating increased the lid dose from 85 to 123% at 6 MeV and 87 to 119% at

A practical neutron shielding design based on data-base interpolation

International Nuclear Information System (INIS)

Jiang, S.H.; Sheu, R.J.

1993-01-01

Neutron shielding design is an important part of the construction of nuclear reactors and high-energy accelerators. Neutron shielding design is also indispensable in the packaging and storage of isotopic neutron sources. Most efforts in the development of neutron shielding design have been concentrated on nuclear reactor shielding because of its huge mass and strict requirement of accuracy. Sophisticated computational tools, such as transport and Monte Carlo codes and detailed data libraries have been developed. In principle, now, neutron shielding, in spite of its complexity, can be designed in any detail and with fine accuracy. However, in most practical cases, neutron shielding design is accomplished with simplified methods. Unlike practical gamma-ray shielding design, where exponential attenuation coupled with buildup factors has been applied effectively and accurately, simplified neutron shielding design, either by using removal cross sections or by applying charts or tables of transmission factors such as the National Council on Radiation Protection and Measurements (NCRP) 38 (Ref. 1) for general neutron protection or to NCRP 51 (Ref. 2) for accelerator neutron shielding, is still very primitive and not well established. The available data are limited in energy range, materials, and thicknesses, and the estimated results are only roughly accurate. It is the purpose of this work to establish a simple, convenient, and user-friendly general-purpose computational tool for practical preliminary neutron shielding design that is reasonably accurate. A wide-range (energy, material, and thickness) data base of dose transmission factors has been generated by applying one-dimensional transport calculations in slab geometry

Review of ORNL-TSF shielding experiments for the gas-cooled Fast Breeder Reactor Program

International Nuclear Information System (INIS)

Abbott, L.S.; Ingersoll, D.T.; Muckenthaler, F.J.; Slater, C.O.

1982-01-01

During the period between 1975 and 1980 a series of experiments was performed at the ORNL Tower Shielding Facility in support of the shield design for a 300-MW(e) Gas Cooled Fast Breeder Demonstration Plant. This report reviews the experiments and calculations, which included studies of: (1) neutron streaming in the helium coolant passageways in the GCFR core; (2) the effectiveness of the shield designed to protect the reactor grid plate from radiation damage; (3) the adequacy of the radial shield in protecting the PCRV (prestressed concrete reactor vessel) from radiation damage; (4) neutron streaming between abutting sections of the radial shield; and (5) the effectiveness of the exit shield in reducing the neutron fluxes in the upper plenum region of the reactor

Gonad Shielding for Patients Undergoing Conventional Radiological Examinations: Is There Cause for Concern?

Directory of Open Access Journals (Sweden)

Karami

2016-04-01

Full Text Available Background Gonad shielding is one of the fundamental methods by which to protect reproductive organs in patients undergoing conventional radiological examinations. A lack of or inadequate shielding of the gonads may increase the exposure of these organs and result in malignancies future generations. Objectives The aim of this study is to investigate the prevalence of gonad shielding in patients undergoing conventional radiological examinations and the availability of gonad shields and gonad shielding protocols in radiology departments. Materials and Methods A retrospective, observational cross-sectional study on the application of gonad shielding, the availability of gonad shields and the existence of gonad shielding protocols in radiology departments was performed in five different hospitals in Ahvaz, Iran. Results The highest application of gonad shielding was 6.6% for the pediatric hospital. The prevalence of gonad shielding was less than 0.2%. In 64.3% of the radiography rooms, at least one flat-contact gonad shield of a large size was available. Only large-sized gonad shields were available. Curved-contact and shadow gonad shields did not exist. Gonad shielding protocols were not existence in any of the fourteen radiography rooms investigated. Conclusions Comprehensive protection programs with on-the-job training courses for staff members are strongly recommended, as well as, the provision of radiological shields and gonad shielding protocols in radiology departments to reduce the patient’s radiation dose during radiological examinations.

Multifunctional BHL Radiation Shield, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Advances in radiation shielding technology remain an important challenge for NASA in order to protect their astronauts, particularly as NASA grows closer to manned...

Shielding calculations using computer techniques; Calculo de blindajes mediante tecnicas de computacion

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Portilla, M. I.; Marquez, J.

2011-07-01

Radiological protection aims to limit the ionizing radiation received by people and equipment, which in numerous occasions requires of protection shields. Although, for certain configurations, there are analytical formulas, to characterize these shields, the design setup may be very intensive in numerical calculations, therefore the most efficient from to design the shields is by means of computer programs to calculate dose and dose rates. In the present article we review the codes most frequently used to perform these calculations, and the techniques used by such codes. (Author) 13 refs.

Shielding requirements for particle bed propulsion systems

Science.gov (United States)

Gruneisen, S. J.

1991-06-01

Nuclear Thermal Propulsion systems present unique challenges in reliability and safety. Due to the radiation incident upon all components of the propulsion system, shielding must be used to keep nuclear heating in the materials within limits; in addition, electronic control systems must be protected. This report analyzes the nuclear heating due to the radiation and the shielding required to meet the established criteria while also minimizing the shield mass. Heating rates were determined in a 2000 MWt Particle Bed Reactor (PBR) system for all materials in the interstage region, between the reactor vessel and the propellant tank, with special emphasis on meeting the silicon dose criteria. Using a Lithium Hydride/Tungsten shield, the optimum shield design was found to be: 50 cm LiH/2 cm W on the axial reflector in the reactor vessel and 50 cm LiH/2 cm W in a collar extension of the inside shield outside of the pressure vessel. Within these parameters, the radiation doses in all of the components in the interstage and lower tank regions would be within acceptable limits for mission requirements.

Study on preparation of ultrafine lead tungstate for radiation protection and γ-ray shielding of the gloves

International Nuclear Information System (INIS)

Du Licheng; He Ping; Zhou Yuanlin; Song Kaiping; Yang Kuihua

2012-01-01

Lead tungstate combines the radiation shielding properties of tungsten and lead, and it is quite distinctive to manufacture lead tungstate with ultra-fine granularity to enhance its capacity of radiation shielding. The grain size of lead tungstate has direct impact on the ability of its protection from radioactive materials. the smaller the grain size and more uniform dispersion of lead tungstate, the better protective ability it is going to be. In this paper, soft-template synthesis was introduced to prepare ultra-fine PbWO 4 . Rigorous experiment conditions are settled to ensure the access to obtain ultra-fine, homogeneous lead tungstate product, and it is better than other physical and chemical preparation methods. The surface-active agent for the soft template, with S-60 for the water system W/O microemulsion zone, was used to synthesize successfully ultra-fine PbWO 4 . It was shown that dispersing agent S-60 in the soft template method produced ultra-fine PbWO 4 with uniform granularity distribution. By using orthogonal experimental method, the best experimental conditions were obtained as follows: S-60 as surfactant dispersant with diluted 30 times concentration, solutions with pH9, 0.01 mol/L concentration of reactant, 1300 rpm of stirring speed and slowly adding drops of Na 2 WO 4 solution into Pb (Ac) 2 solution. Based on the optimal experimental conditions, the product of ultra-fine product for the anti-radiation protection filler has been made. The fine packing for the preparation of tungsten the gamma rays on the gloves is an average capacity of 5% or so. (authors)

Evaluation of the efficacy of pelvic shielding in preadolescent girls.

Science.gov (United States)

Liakos, P; Schoenecker, P L; Lyons, D; Gordon, J E

2001-01-01

A standing anteroposterior pelvic radiograph with gonadal shielding is used as a screening tool for all patients evaluated for intoeing at our institution. Sixty-two normal consecutive screening pelvic radiographs obtained in 61 female patients between the ages of 4 and 6 years were evaluated. Radiographs were evaluated for the adequacy to assess the hips as well as the protection afforded the ovaries from radiation exposure. Radiographs were judged to be inadequate because the shield covered essential landmarks in at least one hip in eight radiographs (13%). Five radiographs (8%) covered >50% of the area of both ovaries, and only one radiograph covered >75% of the area of both ovaries. Standard techniques of positioning gonadal shields in preadolescent girls are inadequate and provide minimal protection with a high rate of interference with vital landmarks. We no longer advocate using gonadal shields on initial screening radiographs of preadolescent girls.

Radiation shield vest and skirt

International Nuclear Information System (INIS)

Maine, G.J.

1982-01-01

A two-piece garment is described which provides shielding for female workers exposed to radiation. The upper part is a vest, overlapping and secured in the front by adjustable closures. The bottom part is a wraparound skirt, also secured by adjustable closures. The two parts overlap, thus providing continuous protection from shoulder to knee and ensuring that the back part of the body is protected as well as the front

Mars Exploration Rover Heat Shield Recontact Analysis

Science.gov (United States)

Raiszadeh, Behzad; Desai, Prasun N.; Michelltree, Robert

2011-01-01

The twin Mars Exploration Rover missions landed successfully on Mars surface in January of 2004. Both missions used a parachute system to slow the rover s descent rate from supersonic to subsonic speeds. Shortly after parachute deployment, the heat shield, which protected the rover during the hypersonic entry phase of the mission, was jettisoned using push-off springs. Mission designers were concerned about the heat shield recontacting the lander after separation, so a separation analysis was conducted to quantify risks. This analysis was used to choose a proper heat shield ballast mass to ensure successful separation with low probability of recontact. This paper presents the details of such an analysis, its assumptions, and the results. During both landings, the radar was able to lock on to the heat shield, measuring its distance, as it descended away from the lander. This data is presented and is used to validate the heat shield separation/recontact analysis.

Determination of half-value layers and tenth-value layer to barite as shielding against X radiation in radiological protection

International Nuclear Information System (INIS)

Lopes, G.A.; Aragao Filho, G.L.; Almeida Junior, A.T.; Santos, M.A.P.; Araujo, F.G.S.; Nogueira, M.S.

2013-01-01

The barium mortar has been widely used as radiation shielding material for X and gamma radiations in Brazil, by presenting some advantages as the high rate of efficiency in radiation shielding, the easy handling and application, the facility to be found in the national market and low cost. The determination of the half-value layers (HVL) and tenth-value layer (TVL) of different types of barite becomes the major factor to characterize the attenuation of these materials, in order to ensure the efficiency and quality of projects shielding, by ensuring the safety of workers occupationally exposed to radiation and of individuals to the public. Thus, plates of different thickness of mortar of barite were made for determination of their HVL and TVL. The plates were irradiated with X-ray qualities for radiological protection according to standard ISO 4037. A system of CdTe spectrometry was used to acquire spectra transmitted, in the presence of each plate, and their combinations. The areas of the spectra obtained, depending on the total thickness of the plates used in the arrangement were used to determine the attenuation curves. From these curves obtained in this work was to establish the HVL and TVL

Combination thermal and radiation shield for well logging apparatus

International Nuclear Information System (INIS)

Wilson, B.F.

1984-01-01

A device for providing both thermal protection and radiation shielding for components such as radiation detectors within a well logging instrument comprises a thermally insulative flask containing a weldment filled with a mass of eutectic material which undergoes a change of state e.g. melting at a temperature which will provide an acceptable thermal environment for such components for extended time periods. The eutectic material which is preferably a bismuth (58%)/tin (42%) alloy has a specific gravity (> 8.5) facilitating its use as a radiation shield and is distributed around the radiation detectors so as to selectively impede the impinging of the detectors by radiation. The device is incorporated in a skid of a well logging instrument for measuring γ backscatter. A γ source is located either above or within the protective shielding. (author)

Graphene shield enhanced photocathodes and methods for making the same

Science.gov (United States)

Moody, Nathan Andrew

2014-09-02

Disclosed are graphene shield enhanced photocathodes, such as high QE photocathodes. In certain embodiments, a monolayer graphene shield membrane ruggedizes a high quantum efficiency photoemission electron source by protecting a photosensitive film of the photocathode, extending operational lifetime and simplifying its integration in practical electron sources. In certain embodiments of the disclosed graphene shield enhanced photocathodes, the graphene serves as a transparent shield that does not inhibit photon or electron transmission but isolates the photosensitive film of the photocathode from reactive gas species, preventing contamination and yielding longer lifetime.

X-ray face mask and chest shield device

International Nuclear Information System (INIS)

Moti, S.

1981-01-01

A protective face mask is designed to shield an x-ray technician or machine operator primarily from random secondary or scatter x-rays deflected towards his face, head and neck by the table, walls, equipment and other reflecting elements in an x-ray room or chamber. The face mask and chest shield device can be mounted on a patient's shoulders in reverse attitude to protect the back of a patient's head and neck from the x-ray beam. The face mask is relatively or substantially transparent and contains lead in combination with a plastic ionomer or comonomer, which to a degree absorbs or resists penetration of the random deflected secondary or scatter x-rays or the x-ray beam through the mask. The face mask is removably attachable to the chest shield for easy application of the device to and support upon the shoulders of the technician or the patient. (author)

Task force's viewpoint of the current BRH Program. Gonad shield, Part F

International Nuclear Information System (INIS)

Dolezal, A.

1975-01-01

A previous report on radiation protection during diagnostic exposure is reviewed. Some topics discussed are: Task Force regulations for the model by which routine use of patient shielding or gonad shielding would be required; shielding in relation to collimation, scatter radiation, and enforcement of regulations; and proposed regulations for reduction of unnecessary radiation

Radiation production and absorption in human spacecraft shielding systems under high charge and energy Galactic Cosmic Rays: Material medium, shielding depth, and byproduct aspects

Science.gov (United States)

Barthel, Joseph; Sarigul-Klijn, Nesrin

2018-03-01

Deep space missions such as the planned 2025 mission to asteroids require spacecraft shields to protect electronics and humans from adverse effects caused by the space radiation environment, primarily Galactic Cosmic Rays. This paper first reviews the theory on how these rays of charged particles interact with matter, and then presents a simulation for a 500 day Mars flyby mission using a deterministic based computer code. High density polyethylene and aluminum shielding materials at a solar minimum are considered. Plots of effective dose with varying shield depth, charged particle flux, and dose in silicon and human tissue behind shielding are presented.

Siege-shield and scale armour. Reciprocal predominance and common evolution

OpenAIRE

Backer, Fabrice De

2011-01-01

As it appears on the earliest depictions of military materials, Early Dynastic people used a huge shield during the sieges of cities, in order to protect their archers shooting at the defenders. In the meantime, the neck, chest and sides of these besieging soldiers were protected with the primitive models of the scale-armour. The shield has seen a fascinating evolution in the ancient Near East as a defensive armour, dominating the light, thin armour for centuries. Then, the spoked-wheel chari...

Siege-shield and scale armour. Reciprocal predominance and common evolution

OpenAIRE

Backer, Fabrice De

2011-01-01

As it appears on the earliest depictions of military materials, Early Dynastic people used a huge shield during the sieges of cities, in order to protect their archers shooting at the defenders. In the meantime, the neck, chest and sides of these besieging soldiers were protected with the primitive models of the scale-armour. The shield has seen a fascinating evolution in the ancient Near East as a defensive armour, dominating the light, thin armour for centuries. Then, the spoked-wh...

Structural shielding of medical X-ray rooms for diagnostic installations

International Nuclear Information System (INIS)

Rabitsch, H.

1979-06-01

In Part I (RIG 8), the various design procedures for shielding against X-rays are discussed and compared. In particular, this comparison is carried out between the shielding obtained conforming to the Austrian Regulations for Radiation Protection and that obtained from the DIN-standard DIN 6812; this latter includes the various operating conditions of diagnostic installations up to 150 kV. Several examples for particular structural shielding components in medical radiation rooms are given. (author)

Electrically nonconductive shield for electric equipment generating ionizing radiation

International Nuclear Information System (INIS)

Aitken, D.

1979-01-01

As a radiation protection shield there is proposed a nonconductive shield fabricated from epoxides or other plastics material and containing finely dispersed radiation absorbing metal. It is to be designed in such a way that it lies in the range of a high electric gradient in the equipment, close to the radiation-producing component. As suitable metals there are mentioned tin, tungsten, and lead resp. their oxides. As an example there is used an X-ray shielding. (RW) 891 RW/RW 892 MKO [de

Shielding for neutrons produced by medical linear accelerators

International Nuclear Information System (INIS)

Rebello, Wilson F.; Silva, Ademir X.

2007-01-01

The shielding system called Multileaf Shielding (MLS) was designed in Brazil to be used for protection patients, who undergo radiotherapy treatment, against undesired neutrons produced in the medical linear accelerator heads. During the conceiving of the MLS it was necessary to evaluate its efficiency. For that purpose, several simulations using the Monte Carlo N-particle radiation transport code, MCNP5, were made, in order to evaluate the response of the new shielding system. The results showed a significant neutron dose reduction after the inclusion of the MLS. This work aims to presenting these simulation results. (author)

Early test facilities and analytic methods for radiation shielding: Proceedings

International Nuclear Information System (INIS)

Ingersoll, D.T.; Ingersoll, J.K.

1992-11-01

This report represents a compilation of eight papers presented at the 1992 American Nuclear Society/European Nuclear Society International Meeting. The meeting is of special significance since it commemorates the fiftieth anniversary of the first controlled nuclear chain reaction. The papers contained in this report were presented in a special session organized by the Radiation Protection and Shielding Division in keeping with the historical theme of the meeting. The paper titles are good indicators of their content and are: (1) The origin of radiation shielding research: The Oak Ridge experience, (2) Shielding research at the hanford site, (3) Aircraft shielding experiments at General Dynamics Fort Worth, 1950-1962, (4) Where have the neutrons gone?, a history of the tower shielding facility, (5) History and evolution of buildup factors, (6) Early shielding research at Bettis atomic power laboratory, (7) UK reactor shielding: then and now, (8) A very personal view of the development of radiation shielding theory

Onboard radiation shielding estimates for interplanetary manned missions

International Nuclear Information System (INIS)

Totemeier, A.; Jevremovic, T.; Hounshel, D.

2004-01-01

The main focus of space related shielding design is to protect operating systems, personnel and key structural components from outer space and onboard radiation. This paper summarizes the feasibility of a lightweight neutron radiation shield design for a nuclear powered, manned space vehicle. The Monte Carlo code MCNP5 is used to determine radiation transport characteristics of the different materials and find the optimized shield configuration. A phantom torso encased in air is used to determine a dose rate for a crew member on the ship. Calculation results indicate that onboard shield against neutron radiation coming from nuclear engine can be achieved with very little addition of weight to the space vehicle. The selection of materials and neutron transport analysis as presented in this paper are useful starting data to design shield against neutrons generated when high-energy particles from outer space interact with matter on the space vehicle. (authors)

Evaluation of usability of the shielding effect for thyroid shield for peripheral dose during whole brain radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Yang, Myung Sic; Park, Ju Kyeong; Lee, Seung Hun; Kim, Yang Su; Lee, Sun Young; Cha, Seok Yong [Dept. of Radiation Oncology, Chonbuk National University Hospital, Jeonju (Korea, Republic of)

2014-12-15

To reduce the radiation dose to the thyroid that is affected to scattered radiation, the shield was used. And we evaluated the shielding effect for the thyroid during whole brain radiation therapy. To measure the dose of the thyroid, 300cGy were delivered to the phantom using a linear accelerator(Clinac iX VARIAN, USA.)in the way of the 6MV X-ray in bilateral. To measure the entrance surface dose of the thyroid, five glass dosimeters were placed in the 10th slice's surface of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. In the same location, to measure the depth dose of the thyroid, five glass dosimeters were placed in the 10th slice by 2.5 cm depth of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. Entrance surface dose of the thyroid were respectively 44.89 mGy at the unshield, 36.03 mGy at the bismuth shield, 31.03 mGy at the 0.5 mmPb shield and 23.21 mGy at a self-made 1.0 mmPb shield. In addition, the depth dose of the thyroid were respectively 36.10 mGy at the unshield, 34.52 mGy at the bismuth shield, 32.28 mGy at the 0.5 mmPb shield and 25.50 mGy at a self-made 1.0 mmPb shield. The thyroid was affected by the secondary scattering dose and leakage dose outside of the radiation field during whole brain radiation therapy. When using a shield in the thyroid, the depth dose of thyroid showed 11-30% reduction effect and the surface dose of thyroid showed 20-48% reduction effect. Therefore, by using the thyroid shield, it is considered to effectively protect the thyroid and can perform the treatment.

Neutron protection material and neutron protection devices made of such material

International Nuclear Information System (INIS)

Ries, W.

1984-01-01

This is concerned with a neutron protection material made of thermoplastic or thermosetting plastic from high molecule hydrocarbon compounds with particularly high hydrogen and carbon contents as braking or shielding material (moderator) for fast neutrons. The plastic can contain boron for absorbing low energy neutrons. The material is used to manufacture foil, plates, pipes, shielding walls, components, bodies for radiation protection equipment, devices and plant and for neutron protection clothes. (orig./HP) [de

Manual on shielded enclosures. Incorporating: Applications guide, procedures guide, basics guide

International Nuclear Information System (INIS)

1992-01-01

This booklet contains a basic guide to the principles of the production of ionizing radiation and to methods of radiation protection and dosimetry, and a discussion of the need for shielded enclosures. Shielding materials and the design of the enclosures are described

Preliminary study for development of low dose radiation shielding material using liquid silicon and metallic compound

Energy Technology Data Exchange (ETDEWEB)

Jang, Seo Goo; Lee, Sung Soo [Dept. of Medical Science, Graduate School of Soonchunhyang University, Asan (Korea, Republic of); Han, Su Chul [Div. of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Kang, Sung Jin [SoonChunHyang University Hospital, Seoul (Korea, Republic of); Lim, Sung Wook [Graduate school of SeJong University, Seoul (Korea, Republic of)

2017-09-15

This study measured and compared the protective clothing using Pb used for shielding in a diagnostic X-ray energy range, and the shielding rates of X-ray fusion shielding materials using Si and TiO{sub 2}. For the experiment, a pad type shielding with a thickness of 1 mm was prepared by mixing Si-TiO{sub 2}, and the X-ray shielding rate was compared with 0.5 mmPb plate of The shielding rate of shielding of 0.5 mmPb plate 95.92%, 85.26 % based on the case of no shielding under each 60kVp, 100kVp tube voltage condition. When the shielding of Si-TiO{sub 2} pad was applied, the shielding rate equal to or greater than 0.5 mmPb plate was obtained at a thickness of 11 mm or more, and the shielding rate of 100% or more was confirmed at a thickness of 13 nn in 60kVp condition. When the shielding of Si-TiO{sub 2} pad was applied, the shielding rate equal to or greater than 0.5 mmPb plate was obtained at a thickness of 17 mm or more, and a shielding rate of 0.5 mmPb plate was observed at a thickness of 23 mm in 100kVp condition. Through the results of this study, We could confirm the possibility of manufacturing radiation protective materials that does not contain lead hazard using various metallic compound and liquid Si. This study shows that possibility of liquid Si and other metallic compound can harmonize easily. Beside, It is flexible and strong to physical stress than Pb obtained radiation protective clothes. But additional studies are needed to increase the shielding rate and reduce the weight.

Innovative technologies for Faraday shield cooling

International Nuclear Information System (INIS)

Rosenfeld, J.H.; Lindemuth, J.E.; North, M.T.; Goulding, R.H.

1995-01-01

Alternative advanced technologies are being evaluated for use in cooling the Faraday shields used for protection of ion cyclotron range of frequencies (ICR) antennae in Tokamaks. Two approaches currently under evaluation include heat pipe cooling and gas cooling. A Monel/water heat pipe cooled Faraday shield has been successfully demonstrated. Heat pipe cooling offers the advantage of reducing the amount of water discharged into the Tokamak in the event of a tube weld failure. The device was recently tested on an antenna at Oak Ridge National Laboratory. The heat pipe design uses inclined water heat pipes with warm water condensers located outside of the plasma chamber. This approach can passively remove absorbed heat fluxes in excess of 200 W/cm 2 ;. Helium-cooled Faraday shields are also being evaluated. This approach offers the advantage of no liquid discharge into the Tokamak in the event of a tube failure. Innovative internal cooling structures based on porous metal cooling are being used to develop a helium-cooled Faraday shield structure. This approach can dissipate the high heat fluxes typical of Faraday shield applications while minimizing the required helium blower power. Preliminary analysis shows that nominal helium flow and pressure drop can sufficiently cool a Faraday shield in typical applications. Plans are in progress to fabricate and test prototype hardware based on this approach

ITER shielding blanket

Energy Technology Data Exchange (ETDEWEB)

Strebkov, Yu [ENTEK, Moscow (Russian Federation); Avsjannikov, A [ENTEK, Moscow (Russian Federation); Baryshev, M [NIAT, Moscow (Russian Federation); Blinov, Yu [ENTEK, Moscow (Russian Federation); Shatalov, G [KIAE, Moscow (Russian Federation); Vasiliev, N [KIAE, Moscow (Russian Federation); Vinnikov, A [ENTEK, Moscow (Russian Federation); Chernjagin, A [DYNAMICA, Moscow (Russian Federation)

1995-03-01

A reference non-breeding blanket is under development now for the ITER Basic Performance Phase for the purpose of high reliability during the first stage of ITER operation. More severe operation modes are expected in this stage with first wall (FW) local heat loads up to 100-300Wcm{sup -2}. Integration of a blanket design with protective and start limiters requires new solutions to achieve high reliability, and possible use of beryllium as a protective material leads to technologies. The rigid shielding blanket concept was developed in Russia to satisfy the above-mentioned requirements. The concept is based on a copper alloy FW, austenitic stainless steel blanket structure, water cooling. Beryllium protection is integrated in the FW design. Fabrication technology and assembly procedure are described in parallel with the equipment used. (orig.).

High performance inboard shield design for the compact TIBER-II test reactor: Appendix A-2

International Nuclear Information System (INIS)

El-Guebaly, L.A.; Sviatoslavsky, I.N.

1987-01-01

The compactness of the TIBER-II reactor has placed a premium on the design of a high performance inboard shield to protect the inner legs of the toroidal field (TF) coils. The available space for shield is constrained to 48 cm and the use of tungsten is mandatory to protect the magnet against the 1.53 MW/m 2 neutron wall loading. The primary requirement for the shield is to limit the fast neutron fluence to 10 19 n/cm 2 . In an optimization study, the performance of various candidate materials for protecting the magnet was examined. The optimum shield consists of a 40 cm thick W layer, followed by an 8 cm thick H 2 O/LiNO 3 layer. The mechanical design of the shield calls for tungsten blocks within SS stiffened panels. All the coolant channels are vertical with more of them in the front where there is a high heat load. The coolant pressure is 0.2 MPa and the maximum structural surface temperature is 0 C. The effects of the detailed mechanical design of the shield and the assembly gaps between the shield sectors on the damage in the magnet were analyzed and peaking factors of ∼2 were found at the hot spots. 2 refs., 6 figs., 2 tabs

Double-layer neutron shield design as neutron shielding application

Science.gov (United States)

Sariyer, Demet; Küçer, Rahmi

2018-02-01

The shield design in particle accelerators and other high energy facilities are mainly connected to the high-energy neutrons. The deep penetration of neutrons through massive shield has become a very serious problem. For shielding to be efficient, most of these neutrons should be confined to the shielding volume. If the interior space will become limited, the sufficient thickness of multilayer shield must be used. Concrete and iron are widely used as a multilayer shield material. Two layers shield material was selected to guarantee radiation safety outside of the shield against neutrons generated in the interaction of the different proton energies. One of them was one meter of concrete, the other was iron-contained material (FeB, Fe2B and stainless-steel) to be determined shield thicknesses. FLUKA Monte Carlo code was used for shield design geometry and required neutron dose distributions. The resulting two layered shields are shown better performance than single used concrete, thus the shield design could leave more space in the interior shielded areas.

A Brief History of Meteoroid and Orbital Debris Shielding Technology for US Manned Spacecraft

Science.gov (United States)

Bjorkman, Michael D.; Hyde, James L.

2008-01-01

Meteoroid and orbital debris shielding has played an important role from the beginning of manned spaceflight. During the early 60 s, meteoroid protection drove requirements for new meteor and micrometeoroid impact science. Meteoroid protection also stimulated advances in the technology of hypervelocity impact launchers and impact damage assessment methodologies. The first phase of meteoroid shielding assessments closed in the early 70 s with the end of the Apollo program. The second phase of meteoroid protection technology began in the early 80 s when it was determined that there is a manmade Earth orbital debris belt that poses a significant risk to LEO manned spacecraft. The severity of the Earth orbital debris environment has dictated changes in Space Shuttle and ISS operations as well as driven advances in shielding technology and assessment methodologies. A timeline of shielding technology and assessment methodology advances is presented along with a summary of risk assessment results.

Radiation protection

International Nuclear Information System (INIS)

Jain, Aman; Sharma, Shivam; Parasher, Abhishek

2014-01-01

Radiation dose measurement, field of radiobiology, is considered to be critical factor for optimizing radiation protection to the health care practitioners, patients and the public. This lead to equipment that has dose - area product meters permanently installed. In many countries and even institution, the range of equipment is vast and with the opportunity for radiation protection and dose recording varies considerably. Practitioners must move with the changed demands of radiation protection but in many cases without assistance of modern advancements in technology Keeping the three basic safety measures Time, Dose and Shielding we can say 'Optimum dose is safe dose' instead of 'No dose is safe dose'. The purpose enclosed within the title 'Radiation Protection'. The use of radiation is expanding widely everyday around the world and crossing boundaries of medical imaging, diagnostic and. The way to get the ''As low as reasonably achievable' is only achievable by using methodology of radiation protection and to bring the concern of general public and practitioners over the hazards of un-necessary radiation dose. Three basic principles of radiation protection are time, distance and shielding. By minimizing the exposure time increasing the distance and including the shielding we can reduce the optimum range of dose. The ability of shielding material to attenuate radiation is generally given as half value layer. This is the thickness of the material which will reduce the amount of radiation by 50%. Lab coat and gloves must be worn when handling radioactive material or when working in a labeled radiation work area. Safety glasses or other appropriate splash shields should be used when handling radioactive material. 1. Reached to low dose level to occupational workers, public as per prescribed dose limit. 2. By mean of ALARA principle we achieved the protection from radiation besides us using the radiation for our benefit

Beta Bremsstrahlung dose in concrete shielding

Energy Technology Data Exchange (ETDEWEB)

Manjunatha, H.C., E-mail: manjunatha@rediffmail.com [Department of Physics, Government college for women, Kolar 563101, Karnataka (India); Chandrika, B.M. [Shravana, 592, Ist Cross, Behind St.Anne s School, PC Extension, Kolar 563101, Karnataka (India); Rudraswamy, B. [Department of Physics, Bangalore University, Bangalore 560056, Karnataka (India); Sankarshan, B.M. [Shravana, 592, Ist Cross, Behind St.Anne s School, PC Extension, Kolar 563101, Karnataka (India)

2012-05-11

In a nuclear reactor, beta nuclides are released during nuclear reactions. These betas interact with shielding concrete and produces external Bremsstrahlung (EB) radiation. To estimate Bremsstrahlung dose and shield efficiency in concrete, it is essential to know Bremsstrahlung distribution or spectra. The present work formulated a new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides ({sup 32}P, {sup 89}Sr, {sup 90}Sr-{sup 90}Y, {sup 90}Y, {sup 91}Y, {sup 208}Tl, {sup 210}Bi, {sup 234}Pa and {sup 40}K) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. The Bremsstrahlung yield in concrete due to {sup 90}Sr-{sup 90}Y is higher than those of other given nuclides. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Z{sub mod}) and Seltzer's data, where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear shielding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study. - Highlights: Black-Right-Pointing-Pointer Betas released in a nuclear reactor interact with shielding concrete and produces Bremsstrahlung. Black-Right-Pointing-Pointer The present work formulated a new method to evaluate the Bremsstrahlung spectrum and dose in concrete. Black-Right-Pointing-Pointer Presented data in concrete provide a quick and convenient reference for radiation protection.

Micrometeoroid and Orbital Debris (MMOD) Shield Ballistic Limit Analysis Program

Science.gov (United States)

Ryan, Shannon

2013-01-01

This software implements penetration limit equations for common micrometeoroid and orbital debris (MMOD) shield configurations, windows, and thermal protection systems. Allowable MMOD risk is formulated in terms of the probability of penetration (PNP) of the spacecraft pressure hull. For calculating the risk, spacecraft geometry models, mission profiles, debris environment models, and penetration limit equations for installed shielding configurations are required. Risk assessment software such as NASA's BUMPERII is used to calculate mission PNP; however, they are unsuitable for use in shield design and preliminary analysis studies. The software defines a single equation for the design and performance evaluation of common MMOD shielding configurations, windows, and thermal protection systems, along with a description of their validity range and guidelines for their application. Recommendations are based on preliminary reviews of fundamental assumptions, and accuracy in predicting experimental impact test results. The software is programmed in Visual Basic for Applications for installation as a simple add-in for Microsoft Excel. The user is directed to a graphical user interface (GUI) that requires user inputs and provides solutions directly in Microsoft Excel workbooks.

Gonad protection for the paediatric patient

International Nuclear Information System (INIS)

Gyll, C.

1988-01-01

A brief article gives examples of hip radiographs of paediatric patients showing misplacement of shields for gonad protection. Shields cut out of lead-PVC sheeting or the fenestration method of shielding are proposed as more successful methods of gonad shielding. (UK)

Makers of clotting medicine not entitled to liability shield.

Science.gov (United States)

1996-02-23

The Indiana Court of Appeals, Second District, reversed a ruling that protected the manufacturer of a hemophilia blood clotting medicine from legal liability. A boy with hemophilia, known in court records as J.K.B. Jr., contracted HIV from the blood clotting medicine, Factor VIII. His parents sued four pharmaceutical companies, Armour Pharmaceutical Company, Cutter Laboratories, Baxter Healthcare Corporation, and Alpha Therapeutics Corporation, alleging that their products caused J.K.B. Jr.'s death. The companies convinced a Superior Court judge that they were protected under the Indiana Blood Shield Statute. The appeals court ruled that pharmaceutical companies are not included in the Blood Shield Statute. The statute was originally established to protect state-approved blood banks, hospitals, and blood storage facilities because they provide a vital public service.

Evaluation of the room shielding thickness of Hi-Art tomotherapy system

International Nuclear Information System (INIS)

Liu Haikuan; Wu Jinhai; Gu Naigu; Gao Yiming; Wang Li; Huang Weiqin; Wang Fengxian

2010-01-01

In this paper, we calculate and evaluate the room shielding thickness of a Hi-Art tomotherapy system, which is a new type of radiotherapy facility. Due to the self-shielding of the accelerator,only scattered beam and beam leakage were considered in calculating the room shielding thickness. The radiation field of the tomotherapy system was used as the basic data to calculate the shielding thickness of every 15 degree solid angle. The maximum shielding thickness required of each shielding wall was at the position with the angle of 15 degree, and the calculated shielding thickness were 1023, 975, 917, 1460, 1147 and 1189 mm for the east wall,south wall,west wall, north wall, the roof and the floor,respectively. According to the calculation results, all shielding walls, ceiling and floor could meet the requirement of the radiation protection, but the north wall thickness of 1200 mm was a little thinner. (authors)

Comparative study on the use of self-shielded packages or returnable shielding for the land disposal of radioactive wastes

International Nuclear Information System (INIS)

Fitzpatrick, J.; Verrall, S.M.

1985-01-01

A comparative study has been carried out on the two philosophies for providing the radiological protection necessary for the transport and handling of packaged intermediate level wastes from their sites of origin to disposal. The two philosophies are self shielding and returnable shielding. The approach taken was to assess the cost and radiological impact differentials of two respective representative waste management procedures. The comparison indicated the merits of each procedure. As a consequence, a hybrid procedure was identified which combines the advantages of each philosophy. This hybrid procedure was used for further comparison. The results of the study indicate that the use of self shielded packages throughout will incur considerable extra expense and give only a small saving in radiological impact. (author)

Shielding practice

International Nuclear Information System (INIS)

Sauermann, P.F.

1985-08-01

The basis of shielding practice against external irradiation is shown in a simple way. For most sources of radiation (point sources) occurring in shielding practice, the basic data are given, mainly in the form of tables, which are required to solve the shielding problems. The application of these data is explained and discussed using practical examples. Thickness of shielding panes of glove boxes for α and β radiation; shielding of sealed γ-radiography sources; shielding of a Co-60 radiation source, and of the manipulator panels for hot cells; damping factors for γ radiation and neutrons; shielding of fast and thermal neutrons, and of bremsstrahlung (X-ray tubes, Kr-85 pressure gas cylinders, 42 MeV betatrons, 20 MeV linacs); two-fold shielding (lead glass windows for hot cells, 14 MeV neutron generators); shielding against scattered radiation. (orig./HP) [de

A new design of a lead-acrylic shield for staff dose reduction in radial and femoral access coronary catheterization

Energy Technology Data Exchange (ETDEWEB)

Eder, H. [Deptartment of Radiation Protection (Germany); Seidenbusch, M.C.; Treitl, M. [Muenchen Univ. Clinical Center (Germany). Inst. for Clinical Radiology; Gilligan, P. [Mater Private Hospital, Dublin (Ireland). Medical Physics

2015-10-15

Today's standard radiation protection during coronary angiography and percutaneous coronary interventions is the combined use of lead acrylic shields and table-mounted lower body protection. Ambient dose measurements, however, have shown that these protection devices need improvement. Using an anthropomorphic physical phantom, various scenarios were investigated with respect to personnel exposure: (a) enlarging the shield (b) adding a flexible protective curtain to the bottom side of the shield, and (c) application of radioprotective patient drapes. For visualization of the dose reduction effect, Monte Carlo simulations were performed. The flexible curtain in contact with the patient's body reduces the ambient dose rate at the operator's position by up to (87.5 % ± 7.1) compared to the situation with the bare shield. The use of both the flexible curtain and the patient drape reduces the ambient dose rate by up to (90.8 % ± 7). Similar results were achieved for the assisting personnel when they were positioned next to the operator. In addition, the enlarged shield provides better protection of the head region of tall operators. Adding a flexible protective curtain to the bottom side of the shield can protect operators from high doses, especially for body parts which are not protected by lead aprons, e.g. head, and eye lenses. This may be important with respect to lower dose limits for eye lenses in future. The protective effect in real-life working conditions is still being evaluated in an ongoing clinical study.

Gonad Shielding for Patients Undergoing Conventional Radiological Examinations: Is There Cause for Concern?

OpenAIRE

Karami; Zabihzadeh; Gholami

2016-01-01

Background Gonad shielding is one of the fundamental methods by which to protect reproductive organs in patients undergoing conventional radiological examinations. A lack of or inadequate shielding of the gonads may increase the exposure of these organs and result in malignancies future generations. Objectives The aim of this study is to investigate the prevalence of gonad shielding in patients undergoing conventional radiological...

Technical experience of the Belgian regulatory body regarding shielded cells

International Nuclear Information System (INIS)

Cortenbosch, G.; Degreef, G.; Noterman, N.; Mommaert, C.; Smidts, O.; Hasendonck, M. van; Drymael, H.; Schmitz, F.; Kennes, C.; Carlier, P.

2010-01-01

Radiation protection and nuclear safety are of paramount importance when operating shielded cells in hot labs and using remote handling tools. Therefore, various aspects should be ensured throughout the lifecycle of nuclear installations disposing of such type of equipment. The presented aspects are the results of the regulatory body experience with this kind of installations (licensing, operations, operating experience, events). This paper will deal with safety considerations such as filtration, fire protection, shielding, ventilation, waste management, separation of the product fluxes, leak tightness, introduction of equipment, interlocks, failsafe components, piloting software, monitoring and education/training. (orig.)

The manufacturing of depleted uranium biological shield components

International Nuclear Information System (INIS)

Metelkin, J.A.

1998-01-01

The unique combination of the physical and mechanical properties of uranium made it possible to manufacture biological shield components of transport package container (TPC) for transportation nuclear power plant irradiated fuel and radionuclides of radiation diagnostic instruments. Protective properties are substantially dependent on the nature radionuclide composition of uranium, that why I recommended depleted uranium after radiation chemical processing. Depleted uranium biological shield (DUBS) has improved specific mass-size characteristics compared to a shield made of lead, steel or tungsten. Technological achievements in uranium casting and machining made it possible to manufacture DUBS components of TPC up to 3 tons of mass and up to 2 metres of the maximum size. (authors)

General Corrosion and Localized Corrosion of the Drip Shield

Energy Technology Data Exchange (ETDEWEB)

F. Hua

2004-09-16

The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847]).

General Corrosion and Localized Corrosion of the Drip Shield

International Nuclear Information System (INIS)

F. Hua

2004-01-01

The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847])

Radiation shielding device

International Nuclear Information System (INIS)

Nakagawa, Takahiro; Yamagami, Makoto.

1996-01-01

A fixed shielding member made of a radiation shielding material is constituted in perpendicular to an opening formed on radiation shielding walls. The fixed shielding member has one side opened and has other side, the upper portion and the lower portion disposed in close contact with the radiation shielding walls. Movable shielding members made of a radiation shielding material are each disposed openably on both side of the fixed shielding member. The movable shielding member has a shaft as a fulcrum on one side thereof for connecting it to the radiation shielding walls. The other side has a handle attached for opening/closing the movable shielding member. Upon access of an operator, when each one of the movable shielding members is opened/closed on every time, leakage of linear or scattered radiation can be prevented. Even when both of the movable shielding members are opened simultaneously, the fixed shielding member and the movable shielding members form labyrinth to prevent leakage of linear radioactivity. (I.N.)

Analytic Shielding Optimization to Reduce Crew Exposure to Ionizing Radiation Inside Space Vehicles

Science.gov (United States)

Gaza, Razvan; Cooper, Tim P.; Hanzo, Arthur; Hussein, Hesham; Jarvis, Kandy S.; Kimble, Ryan; Lee, Kerry T.; Patel, Chirag; Reddell, Brandon D.; Stoffle, Nicholas;

Radiation protective clothing

International Nuclear Information System (INIS)

Fujinuma, Tadashi; Tamura, Shoji; Ijiri, Yasuo.

1988-01-01

Purpose: To obtain radiation protective clothings of excellent workability and durability. Constitution: Protective clothings of the present invention comprise shielding materials for the upper-half of the body having lead foils laminated on one surface and shielding materials for the lower-half of the body a resin sheet containing inorganic powders of high specific gravity. Such protective clothings have a frexibility capable of followings after the movement of the upper-half body and easily follow after the movement such as acute bending of the body near the waste in the lower-half body. (Kamimura, M.)

Is lead shielding of patients necessary during fluoroscopic procedures? A study based on kyphoplasty

Energy Technology Data Exchange (ETDEWEB)

Smith, Joshua R.; Marsh, Rebecca M.; Silosky, Michael S. [University of Colorado School of Medicine, Department of Radiology, Aurora, CO (United States)

2018-01-15

To determine the benefits, risks, and limitations associated with wrapping a patient with lead shielding during fluoroscopy-guided kyphoplasty procedures as a way to reduce operator radiation exposure. An anthropomorphic phantom was used to mimic a patient undergoing a kyphoplasty procedure under fluoroscopic guidance. Radiation measurements of the air kerma rate (AKR) were made at several locations and under various experimental conditions. First, AKR was measured at various angles along the horizontal plane of the phantom and at varying distances from the phantom, both with and without a lead apron wrapped around the lower portion of the phantom (referred to here as phantom shielding). Second, the effect of an operator's apron was simulated by suspending a lead apron between the phantom and the measurement device. AKR was measured for the four shielding conditions - phantom shielding only, operator apron only, both phantom shielding and operator apron, and no shielding. Third, AKR measurements were made at various heights and with varying C-arm angle. At all locations, the phantom shielding provided no substantial protection beyond that provided by an operator's own lead apron. Phantom shielding did not reduce AKR at a height comparable to that of an operator's head. Previous reports of using patient shielding to reduce operator exposure fail to consider the role of an operator's own lead apron in radiation protection. For an operator wearing appropriate personal lead apparel, patient shielding provides no substantial reduction in operator dose. (orig.)

Is lead shielding of patients necessary during fluoroscopic procedures? A study based on kyphoplasty

International Nuclear Information System (INIS)

Smith, Joshua R.; Marsh, Rebecca M.; Silosky, Michael S.

2018-01-01

To determine the benefits, risks, and limitations associated with wrapping a patient with lead shielding during fluoroscopy-guided kyphoplasty procedures as a way to reduce operator radiation exposure. An anthropomorphic phantom was used to mimic a patient undergoing a kyphoplasty procedure under fluoroscopic guidance. Radiation measurements of the air kerma rate (AKR) were made at several locations and under various experimental conditions. First, AKR was measured at various angles along the horizontal plane of the phantom and at varying distances from the phantom, both with and without a lead apron wrapped around the lower portion of the phantom (referred to here as phantom shielding). Second, the effect of an operator's apron was simulated by suspending a lead apron between the phantom and the measurement device. AKR was measured for the four shielding conditions - phantom shielding only, operator apron only, both phantom shielding and operator apron, and no shielding. Third, AKR measurements were made at various heights and with varying C-arm angle. At all locations, the phantom shielding provided no substantial protection beyond that provided by an operator's own lead apron. Phantom shielding did not reduce AKR at a height comparable to that of an operator's head. Previous reports of using patient shielding to reduce operator exposure fail to consider the role of an operator's own lead apron in radiation protection. For an operator wearing appropriate personal lead apparel, patient shielding provides no substantial reduction in operator dose. (orig.)

Spectroscopic Study of Radiation around the Leksell Gamma Knife for Room Shielding Applications

OpenAIRE

Hubert, Alexis

2017-01-01

Any center planning to install a Gamma Knife radiosurgery unit has to provide for an efficient shielding of the treatment room, to protect the patient, the staff and the public, against undesired radiation. The shielding barrier design is controlled by national and international recommendations; the reference documents for gamma ray radiotherapy facilities are the National Council on Radiation Protection and Measurements (NCRP) reports 49 and 151. However, some facts highlighted in this thesi...

Radiation shielding issues on the FMIT

International Nuclear Information System (INIS)

Burke, R.J.; Davis, A.A.; Huang, S.; Morford, R.J.

1981-05-01

The Fusion Materials Irradiation Test Facility (FMIT) is being built to study neutron radiation effects in candidate fusion reactor materials. The FMIT will yield high fluence data in a fusion-like neutron radiation environment produced by the interaction of a 0.1A, 35 MeV deuteron beam with a flowing lithium target. The design of the facility as a whole is driven by a high availability requirement. The variety of radiation environments in the facility requires the use of diverse and extensive shielding. Shielding design throughout the FMIT must accommodate the need for maintenance and operations access while providing adequate personnel and equipment protection

Information booklet on personal protective equipment: eye and face protection

International Nuclear Information System (INIS)

1992-01-01

In all work places where hazards of various kinds are present and the same cannot be totally controlled by engineering methods, suitable personal protective equipment (PPE) shall be used. There are several types of eye and face protection devices available in the market and it is important that employees use the proper type for the particular job. The main classes of eye and face protection devices required for the industrial operations are as follows: (a) eye protection devices which includes: (i) safety goggles (ii) safety spectacles (iii) safety clipons and eye and face protection devices which are (i) eye shield, (ii) face shield, (iii) wire mesh screen guard. Guide lines for selecting appropriate ear and face protection equipment for nuclear installations are given. (M.K.V.). 4 annexures, 1 appendix

Equipment for shielding the gonad region while performing radiographs

International Nuclear Information System (INIS)

Starp, F.

1979-01-01

The shield consists of a fixed square central lead plate and, associated to it, lead sheets arranged linear displaceable and/or rotatable, by means of which the superficial extent may be variated. For protection from damaging and contamination this shield itself is enclosed by a casing in the form of two cup-shaped discs e.g. from plexiglas put one above the other at the edge. (DG) 891 HP/DG 892 MKO [de

Shielding plugs

International Nuclear Information System (INIS)

Makishima, Kenji.

1986-01-01

Purpose: In shielding plugs of an LMFBR type reactor, to restrain natural convection of heat in an annular space between a thermal shield layer and a shield shell, to prevent the lowering of heat-insulation performance, and to alleviate a thermal stress in a reactor container and the shield shell. Constitution: A ring-like leaf spring split in the direction of height is disposed in an annular space between a thermal shield layer and a shield shell. In consequence, the space is partitioned in the direction of height and, therefore, if axial temperature conditions and space width are the same and the space is low, the natural convection is hard to occur. Thus the rise of upper surface temperature of the shielding plugs can prevent the lowering of the heat insulation performance which will result in the increment of shielding plug cooling capacity, thereby improving reliability. In the meantime, since there is mounted an earthquake-resisting support, the thermal shield layer will move for a slight gap in case of an earthquake, being supported by the earthquake-resisting support, and the movement of the thermal shield layer is restricted, thereby maintaining integrity without increasing the stroke of the ring-like spring. (Kawakami, Y.)

Testicular shield for para-aortic radiotherapy and estimation of gonad doses

OpenAIRE

Ravichandran, R.; Binukumar, J. P.; Kannadhasan, S.; Shariff, M. H.; Ghamrawy, Kamal El

2008-01-01

For radiotherapy of para-aortic and abdominal regions in male patients, gonads are to be protected to receive less than 2% of the prescribed dose. A testicular shield was fabricated for abdominal radiotherapy with 15 MV X-rays ((Clinac 2300 CD, Varian AG) with low melting point alloy (Cerroband). The dimensions of the testicular shield were 6.5 cm diameter and 3.5 cm depth with 1.5 cm wall thickness. During treatment, this shield was held in position by a rectangular sponge and Styrofo...

Shielding of manned space stations against Van Allen Belt protons: a preliminary scoping study

International Nuclear Information System (INIS)

Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M.; Corbin, J.M.

1986-09-01

Calculated results are presented to aid in the design of the shielding required to protect astronauts in a space station that is orbiting through the Van Allen proton belt. The geometry considered - a spherical shell shield with a spherical tissue phantom at its center - is only a very approximate representation of an actual space station, but this simple geometry makes it possible to consider a wide range of possible shield materials. Both homogeneous and laminated shields are considered. Also, an approximation procedure - the equivalent thickness approximation - that allows dose rates to be estimated for any shield material or materials from the dose rates for an aluminum shield is presented and discussed

Investigation of Shielding Properties of Yarns, Twisted with Metal Wire

Directory of Open Access Journals (Sweden)

Sandra VARNAITĖ-ŽURAVLIOVA

2014-04-01

Full Text Available The development level of the modern techniques and information technologies creates diverse nature electromagnetic fields and electric field accumulations in the human environment. Electrically conductive textiles that protect against electromagnetic waves and electric charge accumulations can be usable as protective covers for work in computer equipment rooms, measuring stands, air and gas filters and so on. One of the methods used in increase of electrical conductivity in textiles is the development of their specific structures (including the development of threads with the metal component. In this paper, unlike the currently used in the world conductive material production method, where different metal fibres are used as an additives to the main fibre composition in order to create a variety of fibres and yarns, a spun yarn with metal wire was prototyped as samples for this research and the parameters of protective properties of these samples were investigated (such as surface resistivity, vertical resistance, etc.. The protective and shielding properties of woven network with prototyped twisted electro conductive thread with a wire (metal wire diameter of 15 microns were investigated. During the investigation the influence of the following factors, such as conductive fibre composition, electrically conductive thread distribution frequency of the longitudinal and transverse direction, on the protective shielding properties of conductive network were analyzed. The research enabled the assessment of influence of electrically conductive fibre yarn composition and its distribution in the woven mesh on protective shielding properties. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.2492

Radiation dose reduction at a price: the effectiveness of a thyroid shield during head CT scanning

International Nuclear Information System (INIS)

Fu Qiang; Lu Tao; Zhang Ling

2008-01-01

Objective: To assess radiation dose to the thyroid in patients undergoing head CT scanning and to evaluate dose reduction to the thyroid by load shielding. Methods: A post-morterm was scanned by different model and study was undertaken to evaluate the dose reduction by thyroid lead shields and assess their practicality in a clinical setting. (a)No thyroid shields and (b) thyroid shield. One thermoluminescent dosimeters (TLDs)were placed over the thyroid gland center, A thyroid lead shield (Pb eq 0.5mm)was placed around the neck of post-morterm. Scan parameter, CTDIw and DLP were recorded. Results: (a) 0.207mSv; (b) 0.085mSv. A mean effective radiation dose reduction of 58% was seen in the shielded versus the unshielded. Conclusion: Thyroid exposure to scattered radiation from head CT scanning only once is associated with a low but not negligible risk of cancer, but accumulatived doses to the thyroid are serious, highlighting the need for increased awareness of patient radiation protection. Thyroid lead shielding yields significant radiation protection, which should be used routinely during head CT scan. (authors)

The distribution property of shielding materials used in radiological protection

International Nuclear Information System (INIS)

Costa, Paulo R.

1996-01-01

A parametric model for the distribution of the radiation scattered by shielding materials is proposed. The advantages regarding to chemical composition or to linear attenuation coefficient of the media as a function of energy are presented. Comparative results between the model and experimental data are reported

MOSFET Dosimetry for Evaluation of Gonad Shielding during Radiotherapy

International Nuclear Information System (INIS)

Kim, Hwi Young; Choi, Yun Seok; Park, So Yeon; Park, Yang Kyun; Ye, Sung Joon

2011-01-01

In order to confirm feasibility of MOSFET modality in use of in vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of 7.5 cm x 9.5 cm x 5.5 cm sized case and 9 cm x 9.5 cm x 1 cm sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality

MOSFET Dosimetry for Evaluation of Gonad Shielding during Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwi Young; Choi, Yun Seok; Park, So Yeon; Park, Yang Kyun [Seoul National University College of Medicine, Seoul (Korea, Republic of); Ye, Sung Joon [Seoul National University, Seoul (Korea, Republic of)

2011-03-15

In order to confirm feasibility of MOSFET modality in use of in vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of 7.5 cm x 9.5 cm x 5.5 cm sized case and 9 cm x 9.5 cm x 1 cm sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality.

An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

Directory of Open Access Journals (Sweden)

Vida Zaroushani

2015-06-01

Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

The evaluation of the radiation shielding ability of lead glass

International Nuclear Information System (INIS)

Tsuda, Keisuke; Fukushi, Masahiro; Myojoyama, Atsushi; Kitamura, Hideaki; Nakaya, Giichiro; Hassan, Nabil; Inoue, Kazumasa; Kimura, Junichi; Sawaguchi, Masato; Kinase, Sakae; Saito, Kimiaki

2008-01-01

Positron emission tomography (PET) scanning with the tracer 2-[F-18] Fluoro-2deoxy-D-glucose (FDG) is widely used in the clinical PET. However, the photon energy used in the PET scans is considerably higher than that of the X-rays traditionally used in the diagnoses. The radiation protection in the PET institution, therefore, is the remaining problem. Meanwhile, lead glass has attracted considerable attention as a radiation-shielding material for the PET institution. The aim of the present study was to evaluate the radiation-shielding ability of the lead glass against the positron emitters. The shielding ability evaluations were done both in the actual experiments and in the Monte Carlo simulation. The lead glass, the object of evaluation in this study, proved to have sufficient protective effect. The development and the spread of a thinner and lighter lead glass with the same effective dose transmission factor should be expected in the near future. (author)

A survey of Alberta physicians' use of and attitudes toward face masks and face shields in the operating room setting.

Science.gov (United States)

Davis, Philip J; Spady, Donald; Forgie, Sarah E D

2007-09-01

There is little evidence that surgical mask use by physicians in the operating room (OR) reduces surgical site infections (SSIs), but masks do protect the wearer from potentially infectious splashes. Face shields offer even more protection because they cover the eyes, but they may be perceived as offering less protection to the patient than do masks. The objectives of this study were to ascertain if there were predictors to determine which OR physicians are continuing to use masks and what their reasons are for doing so, and which OR physicians would accept face shields and their reasons for doing so. We surveyed the province of Alberta's surgeons, general practice (GP) surgeons, anesthesiologists, and GP anesthetists to determine how many physicians in the OR wear surgical masks, their reasons for wearing surgical masks (ethical, legal, protection of the patient, protection of the wearer), and if they believe that face shields offer more protection to the patient or to the wearer. We also sought to examine which demographic factors affected their responses. The data were examined with chi(2) analysis to assess the relationships of age and practitioner type, and for various outcome variables. A significance level of P masks; masks are worn to prevent the spread of disease, not because it is tradition to do so; masks protect the wearer more than do face shields; and wearing face shields alone will subject the patient to higher rates of SSIs. Surgeons are more likely than are anesthesiologists to wear surgical masks in the OR and wear a surgical mask and a face shield if the patient has risk factors for a blood borne infection. According to our survey, age and profession were the most important variables that affected the potential use of surgical masks and face shields. Younger OR physicians likely would be amenable to using face shields in addition to masks in the OR to protect themselves from exposure to blood or bodily fluids.

Poor Utility of Gonadal Shielding for Pediatric Pelvic Radiographs.

Science.gov (United States)

Lee, Mark C; Lloyd, Jessica; Solomito, Matthew J

2017-07-01

Plain pelvic radiographs are commonly used for a variety of pediatric orthopedic disorders. Lead shielding is typically placed over the gonads to minimize radiation exposure to these sensitive tissues. However, misplaced shielding can sabotage efforts to protect patients from excessive radiation exposure either by not covering radiosensitive tissues or by obscuring anatomic areas of interest, prompting repeat radiographic examinations. The goal of this study was to determine the incidence of misplaced shielding for pelvic radiographs obtained for pediatric orthopedic evaluation. Children 8 to 16 years old who had an anteroposterior or frog lateral pelvic radiograph between 2008 and 2014 were included. A total of 3400 patients met the inclusion criteria, and 84 boys and 84 girls were randomly selected for review. For both boys and girls, the percentage of incorrectly positioned or missing shields was calculated. Chi-square testing was used to compare the frequency of missing or incorrectly placed shields between sexes and age groups. Pelvic shields were misplaced in 49% of anteroposterior and 63% of frog lateral radiographs. Shielding was misplaced more frequently for girls than for boys on frog lateral radiographs (76% vs 51%; P<.05). Pelvic bony landmarks were often obscured by pelvic shielding, with a frequency of 7% to 43%, depending on the specific landmark. The femoral head and acetabulum were obscured by shielding in up to 2% of all images. The findings suggest that accepted pelvic shielding protocols are ineffective. Consideration should be given to alternative protocols or abandonment of this practice. [Orthopedics. 2017; 40(4):e623-e627.]. Copyright 2017, SLACK Incorporated.

Adaptation of radiation shielding code to space environment

International Nuclear Information System (INIS)

Okuno, Koichi; Hara, Akihisa

1992-01-01

Recently, the trend to the development of space has heightened. To the development of space, many problems are related, and as one of them, there is the protection from cosmic ray. The cosmic ray is the radiation having ultrahigh energy, and there was not the radiation shielding design code that copes with cosmic ray so far. Therefore, the high energy radiation shielding design code for accelerators was improved so as to cope with the peculiarity that cosmic ray possesses. Moreover, the calculation of the radiation dose equivalent rate in the moon base to which the countermeasures against cosmic ray were taken was simulated by using the improved code. As the important countermeasures for the safety protection from radiation, the covering with regolith is carried out, and the effect of regolith was confirmed by using the improved code. Galactic cosmic ray, solar flare particles, radiation belt, the adaptation of the radiation shielding code HERMES to space environment, the improvement of the three-dimensional hadron cascade code HETCKFA-2 and the electromagnetic cascade code EGS 4-KFA, and the cosmic ray simulation are reported. (K.I.)

Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields

Energy Technology Data Exchange (ETDEWEB)

Wagh, Arun S., E-mail: asw@anl.gov [Environmental Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Sayenko, S.Yu.; Dovbnya, A.N.; Shkuropatenko, V.A.; Tarasov, R.V.; Rybka, A.V.; Zakharchenko, A.A. [National Science Center, Kharkov Institute of Physics and Technology, Kharkov (Ukraine)

2015-07-15

Highlights: • It incorporates all suggestions by the reviewers. • Explanation to each new term is provided and suitable references are given. • Sample identities have been streamlined by revising the text and the tables. • Some figures have been redrawn. - Abstract: Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid–base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete’s tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

Efficacy of Breast Shielding During CT of the Head

International Nuclear Information System (INIS)

Brnic, Z.; Vekic, B.; Hebrang, A.; Anic, P.

2003-01-01

The use of computerized tomography (CT) is rapidly increasing in last two decades, and this method has become the major non-natural source of radiation exposure to the population. CT examinations delivers to the patients more radiation than all other imaging techniques, and contribute disproportionately to the collective dose; in Britain it has been estimated that 4% of diagnostic radiology procedures are CT examinations, being responsible for approximately 40% of the total annual collective dose. Breast doses are high in CT examinations with breasts in scanning planes, being not insignificant also when breasts are exposed only to scatter radiation. Breast doses received through scatter radiation during head CT may account for up to one-fifth of an average mammographic dose per one view. Whilst the possibilities of reduction of radiation load to organs lying in CT scanning planes are limited, the tissues outside the primary beam should be protected against scatter whenever it does not sacrifice image quality. Lead shielding results in significant reduction of external scatter to radiosensitive superficial organs in many diagnostic procedures. The published studies of breast shielding against scatter radiation in diagnostic radiology are scanty, only the later one dealing particularly with breast shielding during head CT examination. The aims of this study were to investigate in vivo the levels of breast exposure to scatter radiation in head CT examination and the dependence of breast exposure upon body constitution. We tried to estimate the efficacy of external lead shielding as a mean of breast dose reduction, and to determine how much radiation reaches the organ from outside, in comparison to radiation load caused through internal scatter. We conclude that, although the level of breast radiation exposure during head CT examinations is generally low, shielding of the breasts with lead apron will further reduce the doses. However is the effect of shielding limited

Special concrete shield selection using the analytic hierarchy process

International Nuclear Information System (INIS)

Abulfaraj, W.H.

1994-01-01

Special types of concrete radiation shields that depend on locally available materials and have improved properties for both neutron and gamma-ray attenuation were developed by using plastic materials and heavy ores. The analytic hierarchy process (AHP) is implemented to evaluate these types for selecting the best biological radiation shield for nuclear reactors. Factors affecting the selection decision are degree of protection against neutrons, degree of protection against gamma rays, suitability of the concrete as building material, and economic considerations. The seven concrete alternatives are barite-polyethylene concrete, barite-polyvinyl chloride (PVC) concrete, barite-portland cement concrete, pyrite-polyethylene concrete, pyrite-PVC concrete, pyrite-portland cement concrete, and ordinary concrete. The AHP analysis shows the superiority of pyrite-polyethylene concrete over the others

Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule.

Science.gov (United States)

Pugliese, M; Bengin, V; Casolino, M; Roca, V; Zanini, A; Durante, M

2010-08-01

Radiation assessment and protection in space is the first step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding effectiveness of two flexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on flight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no significant effects of shielding, suggesting that thin shields in low-Earth Orbit have little effect on absorbed dose.

Pre-installation empirical testing of room shielding for high dose rate remote afterloaders

International Nuclear Information System (INIS)

Klein, E.E.; Grigsby, P.W.; Williamson, J.F.; Meigooni, A.S.

1993-01-01

PURPOSE: Many facilities are acquiring high dose rate remote afterloading units. It is economical that these units be placed in existing shielded teletherapy rooms. Scatter-radiation barriers marginally protect uncontrolled areas from a high dose rate source especially in a room that houses a non-dynamic Cobalt-60 unit. In addition the exact thickness and material composition of the barriers are unknown and therefore, a calculation technique may give misleading results. Also, it would be impossible to evaluate an entire wall barrier by taking isolated core samples in order to assist in the calculations. A quick and inexpensive measurement of dose equivalent using a rented high activity 192Ir source evaluates the barriers and locates shielding deficiencies. METHODS AND MATERIALS: We performed transmission calculations for primary and scattered radiation based on National Council on Radiation Protection and Measurements Reports 49 and 51, respectively. We then rented a high activity 21.7 Ci (8.03 x 10(11) Bq) Ir-192 source to assess our existing teletherapy room shielding for adequacy and voids. This source was placed at the proposed location for clinical high dose rate treatment and measurements were performed. RESULTS: No deficiencies were found in controlled areas surrounding the room, but large differences were found between the calculated and measured values. Our survey located a region in the uncontrolled area above the room requiring augmented shielding which was not predicted by the calculations. A canopy shield was designed to potentially augment the shielding in the ceiling direction. CONCLUSION: Pre-installation testing by measurement is an invaluable method for locating shielding deficiencies and avoiding unnecessary enhancement of shielding particularly when there is lack of information of the inherent shielding

Rhizobia from Lanzarote, the Canary Islands, that nodulate Phaseolus vulgaris have characteristics in common with LMW RNA group II Sinorhizobium meliloti of Medicago, Melilotus and Trigonella from soils of mainland Spain

Science.gov (United States)

Several isolates from nodules of Phaseolus vulgaris grown in soil of Lanzarote, an island of the Canaries, had electrophoretic LMW RNA patterns identical with a less common pattern within S. meliloti (assigned as group II) obtained from nodules of alfalfa and alfalfa-related legumes grown in northe...

The use of gonad shielding in biomedical radiography

International Nuclear Information System (INIS)

Backe, S.

1991-01-01

The need for specified rules for gonad shielding in X-ray diagnostics have been stressed by staff members in Norwegian hospitals and health institutions. Variable practice has also caused some distress among patients. In order to have a common recommendation for gonad shielding in Denmark, Finland, Iceland, Norway and Sweden, the National Institute of Radiation Hygiene in Norway formulated a proposal for a ''Code of practice''. The recommendation was drafted by a working group with members from the five Nordic countries and was approved by the Nordic radiation protection authorities with a minor changes. The report is divided in two parts. The first part contains the recommeded Code of practice for gonad shielding in medical X-ray diagnostics. The second part contains data and background material. 23 refs., 11 figs., 4 tabs

Application of a dummy eye shield for electron treatment planning

International Nuclear Information System (INIS)

Kang, Sei-Kwon; Park, Soah; Hwang, Taejin; Cheong, Kwang-Ho; Han, Taejin; Kim, Haeyoung; Lee, Me-Yeon; Kim, Kyoung Ju; Oh, Do Hoon; Bae, Hoonsik

2013-01-01

Metallic eye shields have been widely used for near-eye treatments to protect critical regions, but have never been incorporated into treatment plans because of the unwanted appearance of the metal artifacts on CT images. The purpose of this work was to test the use of an acrylic dummy eye shield as a substitute for a metallic eye shield during CT scans. An acrylic dummy shield of the same size as the tungsten eye shield was machined and CT scanned. The BEAMnrc and the DOSXYZnrc were used for the Monte Carlo (MC) simulation, with the appropriate material information and density for the aluminum cover, steel knob and tungsten body of the eye shield. The Pinnacle adopting the Hogstrom electron pencil-beam algorithm was used for the one-port 6-MeV beam plan after delineation and density override of the metallic parts. The results were confirmed with the metal oxide semiconductor field effect transistor (MOSFET) detectors and the Gafchromic EBT2 film measurements. For both the maximum eyelid dose over the shield and the maximum dose under the shield, the MC results agreed with the EBT2 measurements within 1.7%. For the Pinnacle plan, the maximum dose under the shield agreed with the MC within 0.3%; however, the eyelid dose differed by -19.3%. The adoption of the acrylic dummy eye shield was successful for the treatment plan. However, the Pinnacle pencil-beam algorithm was not sufficient to predict the eyelid dose on the tungsten shield, and more accurate algorithms like MC should be considered for a treatment plan. (author)

Modelling and Optimization of Four-Segment Shielding Coils of Current Transformers.

Science.gov (United States)

Gao, Yucheng; Zhao, Wei; Wang, Qing; Qu, Kaifeng; Li, He; Shao, Haiming; Huang, Songling

2017-05-26

Applying shielding coils is a practical way to protect current transformers (CTs) for large-capacity generators from the intensive magnetic interference produced by adjacent bus-bars. The aim of this study is to build a simple analytical model for the shielding coils, from which the optimization of the shielding coils can be calculated effectively. Based on an existing stray flux model, a new analytical model for the leakage flux of partial coils is presented, and finite element method-based simulations are carried out to develop empirical equations for the core-pickup factors of the models. Using the flux models, a model of the common four-segment shielding coils is derived. Furthermore, a theoretical analysis is carried out on the optimal performance of the four-segment shielding coils in a typical six-bus-bars scenario. It turns out that the "all parallel" shielding coils with a 45° starting position have the best shielding performance, whereas the "separated loop" shielding coils with a 0° starting position feature the lowest heating value. Physical experiments were performed, which verified all the models and the conclusions proposed in the paper. In addition, for shielding coils with other than the four-segment configuration, the analysis process will generally be the same.

Simulation of divertor targets shielding during transients in ITER

Energy Technology Data Exchange (ETDEWEB)

Pestchanyi, Sergey, E-mail: serguei.pestchanyi@kit.edu [KIT, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen (Germany); Pitts, Richard; Lehnen, Michael [ITER Organization,Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

2016-11-01

Highlights: • We simulated plasma shielding effect during disruption in ITER using the TOKES code. • It has been found that vaporization is unavoidable under action of ITER transients, but plasma shielding drastically reduces the divertor target damage: the melt pool and the vaporization region widths reduced 10–15 times. • A simplified 1D model describing the melt pool depth and the shielded heat flux to the divertor targets have been developed. • The results of the TOKES simulations have been compared with the analytic model when the model is valid. - Abstract: Direct extrapolation of the disruptive heat flux on ITER conditions predicts severe melting and vaporization of the divertor targets causing their intolerable damage. However, tungsten vaporized from the target at initial stage of the disruption can create plasma shield in front of the target, which effectively protects the target surface from the rest of the heat flux. Estimation of this shielding efficiency has been performed using the TOKES code. The shielding effect under ITER conditions is found to be very strong: the maximal depth of the melt layer reduced 4 times, the melt layer width—more than 10 times and vaporization region shrinks 10–15 times due to shielding for unmitigated disruption of 350 MJ discharge. The simulation results show complex, 2D plasma dynamics of the shield under ITER conditions. However, a simplified analytic model, valid for rough estimation of the maximum value for the shielded flux to the target and for the melt depth at the target surface has been developed.

Re-evaluation of Baby EBM Shielding Thickness

International Nuclear Information System (INIS)

Mohd Rizal Mohd Chulan; Siti Aisah Hashim; Wah, L.K.; Mukhlis Moktar

2013-01-01

The minimum energy required for an electron beam (EB) to be used as an irradiation device is 200 keV. Nuclear Malaysia's home grown EB machine, the Baby EB can generate up to 140 keV. Therefore, to enable it to be used for application, an internal funding was acquired to increase the energy to up to 300 keV. In doing so, the existing shielding with thickness of 0.35 cm for the top frame and 0.7 cm for the middle and bottom frame needs to be reevaluated. This is to ensure that the shield can still provide significant protection from harmful radiation. This re-evaluation is also needed because of the recent change of clean area dose limit from 2.5 μSv/ hr to 1.0 μSv/ hr. The location of Baby EBM also needs to be re-evaluated if the weight reached 4500 kg/ m 2 (concentrated load for laboratories area). From the calculation it was found that the existing shielding is unable to provide the required protection from the harmful radiation. The recommended thicknesses for the shielding are 3.26 cm for the top frame, 3.5 cm for the middle frame and 3.78 for the bottom frame. Therefore, the total weight of the Baby EBM becomes more than 3000 kg/ m 2 (3337.38 kg/ m 2 ) and this justify the need for the Baby EBM to be transferred from first floor (room no.43008), block 43 (ALUTRON building) to a more suitable location. It is preferable that the new location is in a ground floor that can bear the increased weight. (author)

Heat shield manifold system for a midframe case of a gas turbine engine

Energy Technology Data Exchange (ETDEWEB)

Mayer, Clinton A.; Eng, Jesse; Schopf, Cheryl A.

2017-07-25

A heat shield manifold system for an inner casing between a compressor and turbine assembly is disclosed. The heat shield manifold system protects the outer case from high temperature compressor discharge air, thereby enabling the outer case extending between a compressor and a turbine assembly to be formed from less expensive materials than otherwise would be required. In addition, the heat shield manifold system may be configured such that compressor bleed air is passed from the compressor into the heat shield manifold system without passing through a conventional flange to flange joint that is susceptible to leakage.

Evaluation of radiation shielding rate of lead aprons in nuclear medicine

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Hyun; Han, Beom Heui; Lee, Sang Ho [Dept. of Radiological Science, Seonam University, Asan (Korea, Republic of); Hong, Dong Heui [Dept. of Radiological Science, Far East University, Eumseong (Korea, Republic of); Kim, Gi Jin [Dept. of Nuclear Medicine, Konyang University Hospital, Daejeon (Korea, Republic of)

2017-03-15

Considering that the X-ray apron used in the department of radiology is also used in the department of nuclear medicine, the study aimed to analyze the shielding rate of the apron according to types of radioisotopes, thus γ ray energy, to investigate the protective effects. The radioisotopes used in the experiment were the top 5 nuclides in usage statistics {sup 99m}Tc, {sup 18}F, {sup 131}I, {sup 123}I, and {sup 201}Tl, and the aprons were lead equivalent 0.35 mmPb aprons currently under use in the department of nuclear medicine. As a result of experiments, average shielding rates of aprons were {sup 99m}Tc 31.59%, {sup 201}Tl 68.42%, and {sup 123}I 76.63%. When using an apron, the shielding rate of {sup 13}'1I actually resulted in average dose rate increase of 33.72%, and {sup 18}F showed an average shielding rate of –0.315%, showing there was almost no shielding effect. As a result, the radioisotopes with higher shielding rate of apron was in the descending order of {sup 123}I, {sup 201}Tl, {sup 99m}Tc, {sup 18}F, {sup 131}I. Currently, aprons used in the nuclear medicine laboratory are general X-ray aprons, and it is thought that it is not appropriate for nuclear medicine environment that utilizes γ rays. Therefore, development of nuclear medicine exclusive aprons suitable for the characteristics of radioisotopes is required in consideration of effective radiation protection and work efficiency of radiation workers.

Radioprotective shield - an adequate radioprotective device for routine stomatological radiodiagnosis

Energy Technology Data Exchange (ETDEWEB)

Wiltschke, F [Ernst-Moritz-Arndt-Univ., Greifswald (German Democratic Republic); Taschner, P; Koenig, W; Menzel, B [Staatliches Amt fuer Atomsicherheit und Strahlenschutz, Berlin (German Democratic Republic)

1975-01-01

Starting from the shortcomings of the radioprotective devices at present used in routine stomatological radiodiagnosis, the authors describe the advantages of a radioprotective shield which has been produced in the Greifswald University Stomatological Clinic. On the basis of dosimetric studies, the National Board for Nuclear Safety and Radiological Protection of the GDR (Staatliches Amt fuer Atomsicherheit und Strahlenschutz der DDR) could demonstrate the suitability of this shield as a radioprotective device for routine stomatological radiodiagnosis.

Workers radiation protection. Solutions accommodate new needs. The tool box of radiation protection expands itself. Industrial radiology: workers aware of risks. To design a shielded enclosure

International Nuclear Information System (INIS)

Rannou, Alain; Billarand, Yann; Scanff, Pascale; Etard, Cecile; Sage, Julie; Jolivet, Patrick; Israel, Sylvain; Caplin, Helene; Couasnon, Olivier; Cordelle, Anne

2017-01-01

A first article proposes an overview of developments in the field of workers radiation protection. This development is notably motivated by the future dismantling works. It can be noticed that some other issues are considered as more important than radiation protection in the medical field even though radiation protection is a matter of concern for radiology manipulators. Radiation protection is also an issue for workers performing luggage X-ray controls in airports. As revealed by some measurements, artificial radioactivity should be controlled. Radiation protection is planned in relationship with an exposure scenario. The Belgium example is evoked with the development of centralised data and statistics in order to compare workers profiles. A second article comments the evolution of the activity of radiation protection with its new documents, methodologies (notably for operating rooms), and practical studies. While indicating how much the number of specialised workers increased, and how much dose control has been developed in the medical sector, and in terms of workers wearing a ring- or wrist-dosimeter between 2006 and 2015, and also indicating the distribution of controlled workers among sectors, the article outlines that a computation tool is shared between professionals, and how sheets on radionuclides are published and shared. The third article briefly addresses industrial radiology to outlines that workers are always more aware of risks. The last article briefly describes how a shielded enclosure is designed to limit workers exposure

Analysis of radiation shields of BNPP spent fuel pool

International Nuclear Information System (INIS)

Ayoobian, N.; Hadad, K.; Nematollahi, M. R.

2007-01-01

Radioactive protection is one of the most important subjects in nuclear power plants safety. Analysis of BNPP spent fuel pool shielding , as a main source of energetic γ-rays was the main goal of this project. Firstly, we simulated the reactor core using WIMSD-4 neutronic code and the amount of fission product in the fuel assembly (FA) was calculated during the reactor operation. Then, by obtaining the results from the previous calculation and by using MCNP4C nuclear code , the intensity of γ-rays was obtained in layers of spent fuel pool shields. The results have shown that no significant γ-rays passed through these shields. Finally, an accident and resulting exposure dose above the pool was analyzed

Shield calculations, optimization vs. paradigm; Calculos de blindajes, optimizacion vs. paradigma

Energy Technology Data Exchange (ETDEWEB)

Cornejo D, N.; Hernandez S, A.; Martinez G, A. [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41 y 47 Playa C.P. 11300 LaHabana (Cuba)]. e-mail: nestor@cphr.edu.cu

2006-07-01

Many shieldings have been designed under the criteria of 'Maximum dose rates of project'. It has created the paradigm of those 'low dose rates', for the one which not few specialists would consider unacceptable levels of dose rate superior to the units of {mu}Sv.h{sup -1}, independently of the exposure times. At the present time numerous shieldings are being designed considering dose restrictions in real times of exposure. After these new shieldings, the dose rates could be notably superior to those after traditional shieldings, without it implies inadequate designs or constructive errors. In the work significant differences in levels of dose rates and thickness of shieldings estimated by both methods for some typical facilities. It was concluded that the use of real times of exposure is more adequate for the optimization of the Radiological Protection, although this method demands bigger care in its application. (Author)

Dynamic Open-Rotor Composite Shield Impact Test Report

Science.gov (United States)

Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Pereira, J. Michael; Carney, Kelly S.; Emmerling, William C.

2015-01-01

The Federal Aviation Administration (FAA) is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the aircraft. NASA Glenn and Naval Air Warfare Center (NAWC) China Lake collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test a shield that would protect the aircraft passengers and critical systems from a released blade that could impact the fuselage. This report documents the live-fire test from a full-scale rig at NAWC China Lake. NASA provided manpower and photogrammetry expertise to document the impact and damage to the shields. The test was successful: the blade was stopped from penetrating the shield, which validates the design analysis method and the parameters used in the analysis. Additional work is required to implement the shielding into the aircraft.

Regolith Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication

Science.gov (United States)

Hogue, Michael D.; Meuller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Rasky, Daniel J.

2012-01-01

This NIAC project investigated an innovative approach to provide heat shield protection to spacecraft after launch and prior to each EDL thus potentially realizing significant launch mass savings. Heat shields fabricated in situ can provide a thermal-protection system for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Regolith has extremely good insulating properties and the silicates it contains can be used in the fabrication and molding of thermal-protection materials. Such in situ developed heat shields have been suggested before by Lewis. Prior research efforts have shown that regolith properties can be compatible with very-high temperature resistance. Our project team is highly experienced in regolith processing and thermal protection systems (TPS). Routine access to space and return from any planetary surface requires dealing with heat loads experienced by the spacecraft during reentry. Our team addresses some of the key issues with the EDL of human-scale missions through a highly innovative investigation of heat shields that can be fabricated in space by using local resources on asteroids and moons. Most space missions are one-way trips, dedicated to placing an asset in space for economical or scientific gain. However, for human missions, a very-reliable heat-shield system is necessary to protect the crew from the intense heat experienced at very high entry velocities of approximately 11 km/s at approximately Mach 33 (Apollo). For a human mission to Mars, the return problem is even more difficult, with predicted velocities of up to 14 km/s, at approximately Mach 42 at the Earth-atmosphere entry. In addition to human return, it is very likely that future space-travel architecture will include returning cargo to the Earth, either for scientific purposes or for commercial reasons

Dose reduction during CT scanning in an anthropomorphic phantom by the use of a male gonad shield.

Science.gov (United States)

Price, R; Halson, P; Sampson, M

1999-05-01

Shielding the radiosensitive gonads during X-ray exposure has been advocated for plain film radiography for many years. In the UK, gonad shields are not widely employed in routine CT scanning, possibly owing to a perceived difficulty in protecting the gonads from a multidirectional X-ray source. The increasing numbers of CT scanners in the UK, with the large doses they deliver to patients, make potential dose reduction methods an important issue. This study measures the dose reduction achievable by shielding the male gonads with a lead wrap-around protection device. The reductions in dose when shielded both from direct radiation and from indirect radiation scattered from local tissues were studied. The use of the device resulted in a statistically significant reduction in the absorbed testicular dose from both direct and scattered radiation, with no increase in the dose measured in surrounding tissues. In three clinically relevant experimental protocols where the testes were not irradiated directly, the testicular absorbed dose from indirect scatter was reduced by 77-93% of the corresponding non-shielded figure. In these three experiments, image quality was unaltered by the use of the shield. A larger dose reduction was obtained when the shield was used to protect the testes from direct irradiation. However, this was achieved at the expense of considerable image degradation from streak artefact that would effectively prevent the clinical use of the device in this setting.

Gonad protection in young orthopaedic patients.

Science.gov (United States)

Kenny, N; Hill, J

1992-05-30

To determine whether gonad shields are correctly positioned on the pelvic radiographs of children with slipped capital femoral epiphysis. Retrospective study of radiographs taken of children treated by in situ pinning of slipped capital femoral epiphysis between 1 January 1983 and 31 December 1988. Three teaching hospitals in north west England. 32 patients with complete set of radiographs. An average of 10.8 anteroposterior pelvic radiographs plus 8.9 lateral hip radiographs had been performed per patient. Gonad shields had been completely omitted in 137 (40%) anteroposterior pelvic radiographs performed on the 32 patients at the time of completion of the study. In 100 (29%) the gonad shields were adequately protecting the gonads, but in 109 (31%) the gonad shields were not protecting the gonads due to incorrect positioning of the shield. The incorrect positioning of the gonad shields was more commonly found in girls than boys (64 vs 45; p less than 0.012), presumably because of the difficulty in determining gonadal position in relation to surface landmarks. Absence of gonad shields was also more commonly seen in girls (82 v 55; p less than 0.005), but this is not easily explained. Gonad shields are not protecting the gonads in a large percentage of anteroposterior pelvic radiographs (71%) because they have been omitted or inadequately placed. This avoidable excess radiation exposure to the gonads, combined with the inability to shield the gonads in lateral hip radiographs and the large number of radiographs performed, results in the gonads receiving a higher dose of radiation than may otherwise be the case, and may increase the potential for disease in the future offspring of these patients.

TORE-SUPRA: design of thermal radiation shield at 80 K

International Nuclear Information System (INIS)

Aymar, R.; Cordier, J.J.; Deschamps, P.; Gauthier, A.; Perin, J.P.

1982-09-01

The TORE-SUPRA superconducting toroidal magnet operating at liquid helium temperature, must be protected against thermal radiation from the vessels. For this purpose, stainless steel heat shields, cooled at 80 K, are positioned between coil casings at 4.5 K and the vessels, and constitute a double stiff toroid which completely surrounds the magnet. Mockups have been manufactured to study their design and operating problems. Calculations have also been made to analyse the mechanical behaviour of these shields

SPADA: a project to study the effectiveness of shielding materials in space

International Nuclear Information System (INIS)

Pugliese, M.; Casolino, M.; Cerciello, V.

2008-01-01

The SPADA (SPAce Dosimetry for Astronauts) project is a part of an extensive teamwork that aims to optimize shielding solutions against space radiation. Shielding is indeed all irreplaceable tool to reduce, exposure of crews of future Moon and Mars missions. We concentrated our studies on two flexible materials, Kevlar (R) and Nextel (R), because of their ability to protect space infrastructure from micro meteoroids measured radiation hardness of these shielding materials and compared to polyethylene, generally acknowledged as the most effective space radiation shield with practical applications in spacecraft. Both flight test (on the International Space Station and on the Russian FOTON M3 rocket), with passive dosimeters and accelerator-based experiments have been performed. Accelerator tests using high-energy Fe ions have demonstrated that Kevlar is almost as effective as polyethylene in shielding heavy ions, while Nextel is a poor shield against, high-charge and -energy particles. Preliminary results from spaceflight, however, show that for the radiation environment ill low-Earth orbit. dominated by trapped protons, thin shields of Kevlar and Nextel provide limited reduction.

Study of neutron and gamma shielding by lead borate and bismuth lead borate glasses: transparent radiation shielding

International Nuclear Information System (INIS)

Singh, Vishwanath P.; Badiger, N.M.

2013-01-01

Radiation shielding for gamma and neutron is the prominent area in nuclear reactor technology, medical application, dosimetry and other industries. Shielding of these types of radiation requires an appropriate concrete with mixture of low-to-high Z elements which is an opaque medium. The transparent radiation shielding in visible light for gamma and neutron is also extremely essential in the nuclear facilities as lead window. Presently various types of lead equivalent glass oxides have been invented which are transparent as well as provide protection from radiation. In our study we have assessment of effectiveness of neutron and gamma radiation shielding of xPbO.(1-x) B 2 O 3 (x=0.15 to 0.60) and xBi 2 O 3 .(0.80-x) PbO.0.20 B 2 O 3 (x=0.10 to 0.70) transparent borate and bismuth glasses by NXCOM program. The neutron effective mass removal cross section, Σ R /ρ (cm 2 /g) of the lead, bismuth and boron oxides are given. We found invariable Σ R /ρ of various combinations of the lead borate glass for x=0.15 to 0.60 and bismuth lead borate glass for x=0.10 to 0.70. It is observed that the effective removal cross-section for fast neutron (cm -1 ) of lead borate reduces significantly whereas roughly constant for bismuth borate. The gamma mass attenuation coefficients (μ/ρ) of the glasses were also compared with possible experimental values and found comparable. High (μ/ρ) for gamma radiation of the bismuth glasses shows that it is better gamma shielding compared with lead containing glass. However lead borate glasses are better neutron shielding as the neutron removal coefficient are higher. Our investigation is very useful for nuclear reactor technology where prompt neutron of energy 17 MeV and gamma photon up to 10 MeV produced. (author)

Electromagnetic shielding

International Nuclear Information System (INIS)

Tzeng, Wen-Shian V.

1991-01-01

Electromagnetic interference (EMI) shielding materials are well known in the art in forms such as gaskets, caulking compounds, adhesives, coatings and the like for a variety of EMI shielding purposes. In the past, where high shielding performance is necessary, EMI shielding has tended to use silver particles or silver coated copper particles dispersed in a resin binder. More recently, aluminum core silver coated particles have been used to reduce costs while maintaining good electrical and physical properties. (author). 8 figs

Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes

Science.gov (United States)

Basyigit, Celalettin; Uysal, Volkan; Kilinçarslan, Şemsettin; Mavi, Betül; Günoǧlu, Kadir; Akkurt, Iskender; Akkaş, Ayşe

2011-12-01

The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.

Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes

International Nuclear Information System (INIS)

Basyigit, Celalettin; Uysal, Volkan; Kilincarslan, Semsettin; Akkas, Ayse; Mavi, Betuel; Guenoglu, Kadir; Akkurt, Iskender

2011-01-01

The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.

Safety shield for vacuum/pressure chamber viewing port

Science.gov (United States)

Shimansky, R. A.; Spencer, R. S. (Inventor)

1981-01-01

Observers are protected from flying debris resulting from a failure of a vacuum or pressure chamber viewing port following an implosion or explosion by an optically clear shatter resistant safety shield which spaced apart from the viewing port on the outer surface of the chamber.

Structural shielding at irradiation tests with x-rays up to 400 kV

International Nuclear Information System (INIS)

Rabitsch, H.; Schachinger, E.

1979-12-01

Tables worked out in accordance to the dimensioning method following DIN 54113 are given for the determination protective barriers thicknesses against effective and stray radiation in practical operation conditions. The tables comprise irradiation operation with directional and non-directional radiation sources radiators beams collimated and are restricted to steel as dispersive material for the barrier thicknesses against stray radiation. The calculations of protective barriers against stray radiation show that operation with properly chosen primary beam limiting orifice yields in considerable savings in protective shield thickness when compared to operation without or with mismatched orifice to film size. It further shows a relative indifference against changes of the stray area (film size) or the focus - film sheet distance. The protective shield thickness for the most common exposure conditions calculated according to the Austrian Regulations for Radiation Protection are on the safe side when compared to protective barriere thicknesses calculated according to DIN 54113. (V.M.)

Evaluation of radiation shielding rate of lead aprons in nuclear medicine

International Nuclear Information System (INIS)

Han, Sang Hyun; Han, Beom Heui; Lee, Sang Ho; Hong, Dong Heui; Kim, Gi Jin

2017-01-01

Considering that the X-ray apron used in the department of radiology is also used in the department of nuclear medicine, the study aimed to analyze the shielding rate of the apron according to types of radioisotopes, thus γ ray energy, to investigate the protective effects. The radioisotopes used in the experiment were the top 5 nuclides in usage statistics "9"9"mTc, "1"8F, "1"3"1I, "1"2"3I, and "2"0"1Tl, and the aprons were lead equivalent 0.35 mmPb aprons currently under use in the department of nuclear medicine. As a result of experiments, average shielding rates of aprons were "9"9"mTc 31.59%, "2"0"1Tl 68.42%, and "1"2"3I 76.63%. When using an apron, the shielding rate of "1"3'1I actually resulted in average dose rate increase of 33.72%, and "1"8F showed an average shielding rate of –0.315%, showing there was almost no shielding effect. As a result, the radioisotopes with higher shielding rate of apron was in the descending order of "1"2"3I, "2"0"1Tl, "9"9"mTc, "1"8F, "1"3"1I. Currently, aprons used in the nuclear medicine laboratory are general X-ray aprons, and it is thought that it is not appropriate for nuclear medicine environment that utilizes γ rays. Therefore, development of nuclear medicine exclusive aprons suitable for the characteristics of radioisotopes is required in consideration of effective radiation protection and work efficiency of radiation workers

Design and Shielding of Radiotherapy Treatment Facilities; IPEM Report 75, 2nd Edition

Science.gov (United States)

Horton, Patrick; Eaton, David

2017-07-01

Design and Shielding of Radiotherapy Treatment Facilities provides readers with a single point of reference for protection advice to the construction and modification of radiotherapy facilities. The book assembles a faculty of national and international experts on all modalities including megavoltage and kilovoltage photons, brachytherapy and high-energy particles, and on conventional and Monte Carlo shielding calculations. This book is a comprehensive reference for qualified experts and radiation-shielding designers in radiation physics and also useful to anyone involved in the design of radiotherapy facilities.

Survivor shielding. Part C. Improvements in terrain shielding

International Nuclear Information System (INIS)

Egbert, Stephen D.; Kaul, Dean C.; Roberts, James A.; Kerr, George D.

2005-01-01

A number of atomic-bomb survivors were affected by shielding provided by terrain features. These terrain features can be a small hill, affecting one or two houses, or a high mountain that shields large neighborhoods. In the survivor dosimetry system, terrain shielding can be described by a transmission factor (TF), which is the ratio between the dose with and without the terrain present. The terrain TF typically ranges between 0.1 and 1.0. After DS86 was implemented at RERF, the terrain shielding categories were examined and found to either have a bias or an excessive uncertainty that could readily be removed. In 1989, an improvement in the terrain model was implemented at RERF in the revised DS86 code, but the documentation was not published. It is now presented in this section. The solution to the terrain shielding in front of a house is described in this section. The problem of terrain shielding of survivors behind Hijiyama mountain at Hiroshima and Konpirasan mountain at Nagasaki has also been recognized, and a solution to this problem has been included in DS02. (author)

Configuration Design of Detector Shielding for Gamma Prompt Analysis

International Nuclear Information System (INIS)

Elin-Nuraini; Darsono; Elisabeth

2000-01-01

Configuration on design of detector shielding for gamma prompt analysishas been performed. The aim of this design is to obtain effective shieldingmaterial and configuration that able to protect the detector for fastneutron. The result shown that detector shielding configuration that obtainedby configuration of water and concrete, would be able to absorb fast neutronup to 99.5 %. The neutron flux that passed through shielding configuration is2.4 x 10 3 n/cm 2 dt, in the detector position of 60 cm (forward neutron beamdirection) on the X axis and 30 cm (side ward neutron beam direction) on theZ axis of target. On this position (60,30) counting result was 104358 for Pbcollimator and 246652 for PVC collimator. From examination result shown thatthe weight of silicon is in order 175 gram. (author)

Shielding Design and Radiation Shielding Evaluation for LSDS System Facility

International Nuclear Information System (INIS)

Kim, Younggook; Kim, Jeongdong; Lee, Yongdeok

2015-01-01

As the system characteristics, the target in the spectrometer emits approximately 1012 neutrons/s. To efficiently shield the neutron, the shielding door designs are proposed for the LSDS system through a comparison of the direct shield and maze designs. Hence, to guarantee the radiation safety for the facility, the door design is a compulsory course of the development of the LSDS system. To improve the shielding rates, 250x250 covering structure was added as a subsidiary around the spectrometer. In this study, the evaluations of the suggested shielding designs were conducted using MCNP code. The suggested door design and covering structures can shield the neutron efficiently, thus all evaluations of all conditions are satisfied within the public dose limits. From the Monte Carlo code simulation, Resin(Indoor type) and Tungsten(Outdoor type) were selected as the shielding door materials. From a comparative evaluation of the door thickness, In and Out door thickness was selected 50 cm

Experimental Investigation of Multi-layer Insulation Effect on Damage of Stuffed Shield by High-velocity Impact

Directory of Open Access Journals (Sweden)

GUAN Gong-shun

2016-09-01

Full Text Available The stuffed shield with multi-layer insulation(MLI was designed by improving on Al Whipple shield, and a series of high-velocity impact tests were practiced with a two-stage light gas gun facility at vacuum environment. The damage model of the stuffed shield with different MLI location by Al-sphere projectile impacting was obtained. The effect of MLI on damage of the stuffed shield by high-velocity impact was studied. The results indicate when the MLI is located at front side of the first Al-plate, the protection performance of the stuffed shield is improved with the larger perforation diameter of the first Al-plate and more impact kinetic energy dissipation of the projectile. When MLI is arranged at back side of the first Al-plate, the expansion of the secondary debris cloud from projectile impacting the first Al-plate is restrained, it is not good to improve the protection performance of the stuffed shield. When MLI is arranged at front side of the stuffed wall, the perforation size of the stuffed wall increases; when MLI is arranged at front side of the rear wall, the distribution range of crater on the rear wall decreases.

Efficiency of radiation protection means in pediatric roentgenology

International Nuclear Information System (INIS)

Burdina, L.M.; Stavitskij, R.V.; Lapina, T.V.; Yudaev, V.I.; Pavlova, M.K.

1989-01-01

Set of radiation protection means made by MAVIG Company and used in pediatric roentgenology is considered. The set includes protective shields, aprous for medical staff, gloves aprous to protect patient gonades, caps for testicules, protectors, for gonades, irregular devices to shield children during examination of hip joints. Schielding coefficients, which indicate high efficiency of individual protection means produced by MAVIG Company and which may be recommended for widespread application in roentgenology, are given

Improvement of the shield ability and lightweight of a radiation protective apron

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Keun; Jang, Young Il [Kwangju Health College, Kwang-ju (Korea, Republic of); Kim, Jung Min [Junior College of Health Sciences, Korea University, Seoul (Korea, Republic of)

2003-06-15

In this work, we characterized the shield ability and lightweight of radiation protective aprons which were consisted of various metal (Pb, Sn, Ni, Ti and Cu) by measuring the x-ray dose transmitted through the filters. The transmitted ratio and lead equivalent of various metal were obtained by linear interpolation and the lead equivalent of double layered filters contained Pb layer was determined. The transmitted ratio of the apron (0.25 mmPb) specified in KS B 0845 was 5.2%. The transmitted ratio of the filters at the thickness of 0.6 mm was decreased in the order of Ni (32.60%), Ti (17.75%), Cu (13.25%) and Sn (3.84%). From the results of experimental evaluation for combined filter of Pb and Sn, it was founded that in the case of the first Sn layer, the lead equivalent was higher than that of the first Pb layer. The lead equivalent corresponding to apron of 0.25 mmPb was obtained in the double layered filters of Sn (0.19 mm)-Pb (0.1 mm) and Pb (0.1 mm)-Sn (0.37 mm). Thus, the Sn-Pb filter had the lower weight about 13% than apron of 0.25 mmPb.

Improvement of the shield ability and lightweight of a radiation protective apron

International Nuclear Information System (INIS)

Kim, Young Keun; Jang, Young Il; Kim, Jung Min

2003-01-01

In this work, we characterized the shield ability and lightweight of radiation protective aprons which were consisted of various metal (Pb, Sn, Ni, Ti and Cu) by measuring the x-ray dose transmitted through the filters. The transmitted ratio and lead equivalent of various metal were obtained by linear interpolation and the lead equivalent of double layered filters contained Pb layer was determined. The transmitted ratio of the apron (0.25 mmPb) specified in KS B 0845 was 5.2%. The transmitted ratio of the filters at the thickness of 0.6 mm was decreased in the order of Ni (32.60%), Ti (17.75%), Cu (13.25%) and Sn (3.84%). From the results of experimental evaluation for combined filter of Pb and Sn, it was founded that in the case of the first Sn layer, the lead equivalent was higher than that of the first Pb layer. The lead equivalent corresponding to apron of 0.25 mmPb was obtained in the double layered filters of Sn (0.19 mm)-Pb (0.1 mm) and Pb (0.1 mm)-Sn (0.37 mm). Thus, the Sn-Pb filter had the lower weight about 13% than apron of 0.25 mmPb

Gonadal shielding to irradiation is effective in protecting testicular growth and function in long-term survivors of bone marrow transplantation during childhood or adolescence.

Science.gov (United States)

Ishiguro, H; Yasuda, Y; Tomita, Y; Shinagawa, T; Shimizu, T; Morimoto, T; Hattori, K; Matsumoto, M; Inoue, H; Yabe, H; Yabe, M; Shinohara, O; Kato, S

2007-04-01

An increasing number of long-term surviving bone marrow transplantation (BMT) recipients have recovered from their primary disease but are at risk of developing failure of endocrine organs. We investigated 30 recipients who underwent allogeneic BMT during childhood or adolescence. Testicular growth and function were evaluated by serial measurement of testicular volume, basal luteinizing hormone (LH), basal follicle-stimulating hormone (FSH) and testosterone levels and by gonadotropin-releasing hormone (GnRH) provocative test. Puberty started spontaneously in all patients. However, all except four patients had normal testosterone levels with elevated LH, indicating partial Leydig cell dysfunction. Standard deviation scores of testicular volume at last evaluation were statistically lower in those who had received irradiation without gonadal shield compared to those with (-2.04+/-0.45 vs -0.30+/-1.17, respectively, Pgonadal irradiation. Serial measurement of testicular volume showed a tendency of growth to stop at 10 ml in those without gonadal shield. Among the 30 patients, only one patient has fathered a child after reaching spontaneous puberty. These results suggest that gonadal shield is effective to protect testicular growth and function, although the attainment of fertility is difficult to achieve.

Highly Efficient and Reliable Transparent Electromagnetic Interference Shielding Film.

Science.gov (United States)

Jia, Li-Chuan; Yan, Ding-Xiang; Liu, Xiaofeng; Ma, Rujun; Wu, Hong-Yuan; Li, Zhong-Ming

2018-04-11

Electromagnetic protection in optoelectronic instruments such as optical windows and electronic displays is challenging because of the essential requirements of a high optical transmittance and an electromagnetic interference (EMI) shielding effectiveness (SE). Herein, we demonstrate the creation of an efficient transparent EMI shielding film that is composed of calcium alginate (CA), silver nanowires (AgNWs), and polyurethane (PU), via a facile and low-cost Mayer-rod coating method. The CA/AgNW/PU film with a high optical transmittance of 92% achieves an EMI SE of 20.7 dB, which meets the requirements for commercial shielding applications. A superior EMI SE of 31.3 dB could be achieved, whereas the transparent film still maintains a transmittance of 81%. The integrated efficient EMI SE and high transmittance are superior to those of most previously reported transparent EMI shielding materials. Moreover, our transparent films exhibit a highly reliable shielding ability in a complex service environment, with 98 and 96% EMI SE retentions even after 30 min of ultrasound treatment and 5000 bending cycles (1.5 mm radius), respectively. The comprehensive performance that is associated with the facile fabrication strategy imparts the CA/AgNW/PU film with great potential as an optimized EMI shielding material in emerging optoelectronic devices, such as flexible solar cells, displays, and touch panels.

Protective effect of blue-light shield eyewear for adults against light pollution from self-luminous devices used at night.

Science.gov (United States)

Ayaki, Masahiko; Hattori, Atsuhiko; Maruyama, Yusuke; Nakano, Masaki; Yoshimura, Michitaka; Kitazawa, Momoko; Negishi, Kazuno; Tsubota, Kazuo

2016-01-01

We investigated sleep quality and melatonin in 12 adults who wore blue-light shield or control eyewear 2 hours before sleep while using a self-luminous portable device, and assessed visual quality for the two eyewear types. Overnight melatonin secretion was significantly higher after using the blue-light shield (P light shield (P light shield as providing acceptable visual quality.

Investigation of Lightning and EMI Shielding Properties of SWNT Buckypaper Nanocomposites

National Research Council Canada - National Science Library

Wang, Ben; Liang, Richard; Zhang, Chuck; Kramer, Leslie; Funchess, Percy

2005-01-01

... EMI and lightning strike protection properties. The EMI shielding and lightning strike attenuation properties of the composites with the surface layer of SWNT buckypaper nanocomposite were preliminarily characterized...

Shielding benchmark problems

International Nuclear Information System (INIS)

Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Kawai, Masayoshi; Nakazawa, Masaharu.

1978-09-01

Shielding benchmark problems were prepared by the Working Group of Assessment of Shielding Experiments in the Research Comittee on Shielding Design of the Atomic Energy Society of Japan, and compiled by the Shielding Laboratory of Japan Atomic Energy Research Institute. Twenty-one kinds of shielding benchmark problems are presented for evaluating the calculational algorithm and the accuracy of computer codes based on the discrete ordinates method and the Monte Carlo method and for evaluating the nuclear data used in the codes. (author)

Evaluation of the frequency and accuracy of gonad shield placement in patients undergoing pelvic radiography

Energy Technology Data Exchange (ETDEWEB)

Karami, V.; Zabihzadeh, Mansour; Sarikhani, S. [Ahvaz Jundishapur University of Medical Sciences, Ahvaz (Iran, Islamic Republic of)

2016-11-01

Gonad shielding has been advocated to reduce radiation exposure in patients undergoing pelvic radiography. The aim of this study is to evaluate the frequency and accuracy of gonad shield placement in patients undergoing pelvic radiography. A retrospective study was performed on 1230 anteroposterior (AP) pelvic radiographs of 939 children under 16 years old. All the radiographs were reviewed to determine the frequency of gonad shielding and to evaluate whether gonad shields were correctly positioned when they are used. The gonad shield was present in 82 radiographs (30 girls and 52 boys) and was completely disregarded in 1148 radiographs. From 82 images which shield was present, the gonad shields adequately positioned in 28 radiographs (3 girls and 25 boys) and in the remaining 54 radiographs, the shield did not adequately protected the gonads due to incorrect placement of the shield. The inaccuracy placement and absence of gonad shields were more common in girls than boys (P-value < 0.05). More care should be taken to correctly positioning of the gonad shields in boys and its usage should be encouraged. However, the practice of ovarian shielding is not an effective way to reduce radiation exposure in girls undergoing pelvis radiography. (author)

Evaluation of the frequency and accuracy of gonad shield placement in patients undergoing pelvic radiography

International Nuclear Information System (INIS)

Karami, V.; Zabihzadeh, Mansour; Sarikhani, S.

2016-01-01

Gonad shielding has been advocated to reduce radiation exposure in patients undergoing pelvic radiography. The aim of this study is to evaluate the frequency and accuracy of gonad shield placement in patients undergoing pelvic radiography. A retrospective study was performed on 1230 anteroposterior (AP) pelvic radiographs of 939 children under 16 years old. All the radiographs were reviewed to determine the frequency of gonad shielding and to evaluate whether gonad shields were correctly positioned when they are used. The gonad shield was present in 82 radiographs (30 girls and 52 boys) and was completely disregarded in 1148 radiographs. From 82 images which shield was present, the gonad shields adequately positioned in 28 radiographs (3 girls and 25 boys) and in the remaining 54 radiographs, the shield did not adequately protected the gonads due to incorrect placement of the shield. The inaccuracy placement and absence of gonad shields were more common in girls than boys (P-value < 0.05). More care should be taken to correctly positioning of the gonad shields in boys and its usage should be encouraged. However, the practice of ovarian shielding is not an effective way to reduce radiation exposure in girls undergoing pelvis radiography. (author)

Characterization of a lead breast shielding for dose reduction in computed tomography

Energy Technology Data Exchange (ETDEWEB)

Correia, Paula Duarte; Brochi, Marco Aurelio Corte; Azevedo-Marques, Paulo Mazzoncini de, E-mail: pauladuarte@usp.br [Universidade de Sao Paulo (FM/RSP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina; Granzotti, Cristiano Roberto Fabri; Santos, Yago da Silva [Universidade de Sao Paulo (FFCLRP/RSP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras

2014-07-15

Objective: several studies have been published regarding the use of bismuth shielding to protect the breast in computed tomography (CT) scans and, up to the writing of this article, only one publication about barium shielding was found. The present study was aimed at characterizing, for the first time, a lead breast shielding. Materials and methods: the percentage dose reduction and the influence of the shielding on quantitative imaging parameters were evaluated. Dose measurements were made on a CT equipment with the aid of specific phantoms and radiation detectors. A processing software assisted in the qualitative analysis evaluating variations in average CT number and noise on images. Results: the authors observed a reduction in entrance dose by 30% and in CTDIvol by 17%. In all measurements, in agreement with studies in the literature, the utilization of cotton fiber as spacer object reduced significantly the presence of artifacts on the images. All the measurements demonstrated increase in the average CT number and noise on the images with the presence of the shielding. Conclusion: as expected, the data observed with the use of lead shielding were of the same order as those found in the literature about bismuth shielding. (author)

Radiation shielding for the Super Collider West Utility region

International Nuclear Information System (INIS)

Meinke, R.; Mokhov, N.; Orth, D.; Parker, B.; Plant, D.

1994-02-01

Shielding considerations in the 20 x 20-TeV Superconducting Super Collider are strongly correlated with detailed machine specifics in the various accelerator sections. The West Utility, the most complex area of the Collider, concentrates all the major accelerator subsystems in a single area. The beam loss rate and associated radiation levels in this region are anticipated to be quite high, and massive radiation shielding is therefore required to protect personnel, Collider components, and the environment. The challenging task of simultaneously optimizing accelerator design and radiation shielding, both of which are strongly influenced by subsystem design details, requires the integration of several complex simulation codes. To this end we have performed exhaustive hadronic shower simulations with the MARS12 program; detailed accelerator lattice and optics optimization via the SYNCH, MAD, and MAGIC codes; and extensive 3-D configuration modeling of the accelerator tunnel and subsystems geometries. Our technique and the non-trivial results from such a combined approach are presented here. An integrated procedure is found invaluable in developing cost-effective radiation shielding solutions

Radiation protection during hybrid procedures: innovation creates new challenges.

Science.gov (United States)

Sawdy, Jaclynn M; Gocha, Mark D; Olshove, Vincent; Chisolm, Joanne L; Hill, Sharon L; Phillips, Alistair; Galantowicz, Mark; Cheatham, John P; Holzer, Ralf J

2009-09-01

The cooperation between interventional cardiologists and cardiothoracic surgeons has expanded the spectrum of treatment modalities for patients with congenital heart disease. These hybrid techniques have created new challenges, one of which being the provision of adequate but practical radiation protection. This study evaluates the use of a lightweight radiation protection drape (RADPAD) that may be suitable for shielding during hybrid procedures. To simulate a pediatric patient, an 8.7 liter water-filled tub was placed on an X-ray table and exposed to 10-second cine acquisition runs. Radiation exposure was measured at twelve specified locations around the table using a model with three different levels of radiation protection: no shielding, shielding using a traditional 0.35 mm lead-equivalent apron, and shielding using the 0.25 mm lead-equivalent RADPAD. The traditional lead apron and the RADPAD significantly reduced the amount of radiation dose when compared with no shielding. The standard lead apron provided slightly greater radiation protection than the RADPAD (0.000064 radiation absorbed dose [rad] vs. 0.000091 rad; p = 0.012). The measured rad was significantly higher on the right side of the table, and the measured radiation dose decreased significantly with increasing distance from the table. The RADPAD has been shown to function as an efficient shielding device, even though it does not quite match the protection that can be expected from a standard lead apron. It complies with regulatory radiation protection requirements and its lightweight and sterile use make it particularly useful during hybrid procedures in the operating room.

Evaluation of eye shields made of tungsten and aluminum in high-energy electron beams

International Nuclear Information System (INIS)

Weaver, Randi D.; Gerbi, Bruce J.; Dusenbery, Kathryn E.

1998-01-01

Purpose: To protect the lens and cornea of the eye when treating the eyelid with electrons, we designed a tungsten and aluminum eye shield that protected both the lens and cornea, and also limited the amount of backscatter to the overlying eyelid when using electron beam therapy. Methods and Materials: Custom curved tungsten eye shields, 2 mm and 3 mm thick, were placed on Kodak XV film on 8 cm polystyrene and irradiated to evaluate the transmission through the shields. To simulate the thickness of the eyelid and to hold the micro-TLDs, an aquaplast mold was made to match the curvature of the eye shields. Backscatter was measured by placing the micro-TLDs on the beam entrance side to check the dose to the underside of the eyelid. Measurements were done with no aluminum, 0.5, and 1.0 mm of aluminum on top of the tungsten eye shields. The measurements were repeated with 2- and 3-mm flat pieces of lead to determine both the transmission and the backscatter dose for this material. Results: Tungsten proved to be superior to lead for shielding the underlying structures and for reducing backscatter. At 6 MeV, a 3-mm flat slab of tungsten plus 0.5 mm of aluminum, resulted in .042 Gy under the shield when 1.00 Gy is delivered to d max . At 6 MeV for a 3-mm lead plus 0.5-mm aluminum, .046 Gy was measured beneath the shield, a 9.5% decrease with the tungsten. Backscatter was also decreased from 1.17 to 1.13 Gy, a 4% decrease, when using tungsten plus 0.5 mm of aluminum vs. the same thickness of lead. Measurements using 9 MeV were performed in the same manner. With 3 mm tungsten and 0.5 mm of aluminum, at 3 mm depth the dose was .048 Gy compared to .079 Gy with lead and aluminum (39% decrease). Additionally, the backscatter dose was 3% less using tungsten. Simulating the lens dose 3 mm beyond the shield for the 2-mm and 3-mm custom curved tungsten eye shields plus 0.5 mm of aluminum was .030 and .024 Gy, respectively, using 6 MeV (20% decrease). Using 9-MeV electrons, the dose

Electromagnetic shielding formulae

International Nuclear Information System (INIS)

Dahlberg, E.

1979-02-01

This addendum to an earlier collection of electromagnetic shielding formulae (TRITA-EPP-75-27) contains simple transfer matrices suitable for calculating the quasistatic shielding efficiency for multiple transverse-field and axial-field cylindrical and spherical shields, as well as for estimating leakage fields from long coaxial cables and the normal-incidence transmission of a plane wave through a multiple plane shield. The differences and similarities between these cases are illustrated by means of equivalent circuits and transmission line analogies. The addendum also includes a discussion of a possible heuristic improvement of some shielding formulae. (author)

Handbook of radiation shielding data

International Nuclear Information System (INIS)

Courtney, J.C.

1976-07-01

This handbook is a compilation of data on units, conversion factors, geometric considerations, sources of radiation, and the attenuation of photons, neutrons, and charged particles. It also includes related topics in health physics. Data are presented in tabular and graphical form with sufficient narrative for a least first-approximation solutions to a variety of problems in nuclear radiation protection. Members of the radiation shielding community contributed the information in this document from unclassified and uncopyrighted sources, as referenced

Shielding proposal to reduce cross-talk from ITER lower port to equatorial port

Energy Technology Data Exchange (ETDEWEB)

Juarez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Catalan, J.P.; Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

2015-12-15

Radiation cross-talk from Torus Cryopump LP to EP was found to be a phenomenon driving Shutdown Dose Rates at EP Port Interspace after 12 days of cooling time, as relevant as neutron permeation through EP itself. In this work three different shields are proposed to mitigate the radiation cross-talk: two neutron shields placed inside LP, and a temporary gamma shield placed at EP PI during maintenance activities. Contributions from different reactor regions to Shutdown Dose Rates are computed, for the unshielded design, as long as the different shielded cases. The Rigorous-Two-Steps (R2S) method was used. The neutron shields inside TCP-LP are found to reduce SDR at EP PI 43 μSv/h and 99 μSv/h, while the gamma shield inside EP PI offers a reduction of 157 μSv/h in its heaviest configuration. Among these relevant reductions, the gamma shield inside the EP PI offers the best shielding option, as it reduces gamma cross-talk from TCP-LP and also protects EP PI from Port Duct and EP bellows activation, while it does not interfere with TCP performance.

Lessons from shielding retrofits at the LAMPF/LANSCE/PSR accelerator, beam lines and target facilities

International Nuclear Information System (INIS)

Macek, R.J.

1994-01-01

The experience in the past 7 years to improve the shielding and radiation control systems at the Los Alamos Meson Physics Facility (LAMPF) and the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) provides important lessons for the design of radiation control systems at future, high beam power proton accelerator facilities. Major issues confronted and insight gained in developing shielding criteria and in the use of radiation interlocks are discussed. For accelerators and beam lines requiring hands-on-maintenance, our experience suggests that shielding criteria based on accident scenarios will be more demanding than criteria based on routinely encountered beam losses. Specification and analysis of the appropriate design basis accident become all important. Mitigation by active protection systems of the consequences of potential, but severe, prompt radiation accidents has been advocated as an alternate choice to shielding retrofits for risk management at both facilities. Acceptance of active protection systems has proven elusive primarily because of the difficulty in providing convincing proof that failure of active systems (to mitigate the accident) is incredible. Results from extensive shielding assessment studies are presented including data from experimental beam spill tests, comparisons with model estimates, and evidence bearing on the limitations of line-of-sight attenuation models in complex geometries. The scope and significant characteristics of major shielding retrofit projects at the LAMPF site are illustrated by the project to improve the shielding beneath a road over a multiuse, high-intensity beam line (Line D)

Nuclear characteristics of epoxy resin as a space environment neutron shielding

Energy Technology Data Exchange (ETDEWEB)

Adeli, Ruhollah [Nuclear Science and Technology Research Institute, Yazd (Iran, Islamic Republic of). Central Iran Research Complex; Shirmardi, Seyed Pezhman [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School; Mazinani, Saideh [Amirkabir Nanotechnology Research Institute, Tehran (Iran, Islamic Republic of); Ahmadi, Seyed Javad [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Nuclear Fuel Cycle Research School

2017-03-15

In recent years many investigations have been done for choosing applicable light neutron shielding in space environmental applications. In this study, we have considered the neutron radiation-protective characteristics of neat epoxy resin, a thermoplastic polymer material and have compared it with various candidate materials in neutron radiation protection such as Al 6061 alloy and Polyethylene. The aim of this investigation is the effect of type of moderator for fast neutron, notwithstanding neutron absorbers fillers. The nuclear interactions and the effective dose at shields have been studied with the Monte Carlo N-Particle transport code (MCNP), using variance reductions to reduce the relative error. Among the candidates, polymer matrix showed a better performance in attenuating fast neutrons and caused a lower neutron and secondary photon effective dose.

Shielding member for thermonuclear device

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Masanori

1997-06-30

In a thermonuclear device for shielding fast neutrons by shielding members disposed in a shielding vessel (vacuum vessel and structures such as a blanket disposed in the vacuum vessel), the shielding member comprises a large number of shielding wires formed fine and short so as to have elasticity. The shielding wires are sealed in a shielding vessel together with water, and when the width of the shielding vessel is changed, the shielding wires follow after the change of the width while elastically deforming in the shielding vessel, so that great stress and deformation are not formed thereby enabling to improve reliability. In addition, the length, the diameter and the shape of each of the shielding wires can be selected in accordance with the shielding space of the shielding vessel. Even if the shape of the shielding vessel is complicated, the shielding wires can be inserted easily. Accordingly, the filling rate of the shielding members can be changed easily. It can be produced more easily compared with a conventional spherical pebbles. It can be produced more easily than existent spherical shielding pebbles thereby enabling to reduce the production cost. (N.H.)

Optimisation of the radiation shielding of medical cyclotrons using a genetic algorithm

International Nuclear Information System (INIS)

Mukherjee, Bhaskar

2000-01-01

Effective radiation shielding is imperative for safe operation of modern Medical Cyclotrons producing large activities of short-lived radioisotopes on a commercial basis. The optimal cyclotron shielding design demands a careful balance between the radiological, economical and often the sociopolitical factors. One is required to optimize the cost of radiation protection and the cost of radiological-health detriment. The cost of radiation protection depends explicitly on a) the nature of the radiation field produced by the cyclotron, b) the cyclotron operation condition, c) the cost of shielding material, d) the level of dose reduction, e) the projected net revenue from the sale of the radioisotopes, and f) the depreciation rate of the cyclotron facility. The Genetic Algorithm (GA) is used for a cost -benefit analysis of this problem. The GA is a mathematical technique that emulates the Darwinian Evolution paradigm. It is ideally suited to search for a global optimum in a large multi-dimensional solution space, having demonstrated strength compared to the classical analytical methods. Furthermore the GA method runs on a PC in a Windows environment. This paper highlights an interactive spreadsheet macro program for the cost benefit analysis of the optimize Medical Cyclotron shielding using a GA search engine. (author)

Space Station Validation of Advanced Radiation-Shielding Polymeric Materials, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — In Subtopic X11.01, NASA has identified the need to develop advanced radiation-shielding materials and systems to protect humans from the hazards of space radiation...

Experimental Studies on Shadow Shields for Thermal Protection of Cryogenic Tanks in Space

National Research Council Canada - National Science Library

Knoll, Richard

1968-01-01

... (high-emissivity coatings on annular rings of shields) on thermal performance. The experimental data, in general, agreed closely with an analytical model which assumed diffuse surfaces with nonuniform radiosity...

A contribution to shielding effectiveness analysis of shielded tents

Directory of Open Access Journals (Sweden)

Vranić Zoran M.

2004-01-01

Full Text Available An analysis of shielding effectiveness (SE of the shielded tents made of the metallised fabrics is given. First, two electromagnetic characteristic fundamental for coupling through electrically thin shield, the skin depth break frequency and the surface resistance or transfer impedance, is defined and analyzed. Then, the transfer function and the SE are analyzed regarding to the frequency range of interest to the Electromagnetic Compatibility (EMC Community.

Shielding behavior of multi-transformation phase change materials (MTPCM) against nuclear radiations

International Nuclear Information System (INIS)

Kumar, Ravindra; Goplani, Deepak; Kumar, Rohitash; Das, Mrinal Kumar; Kumar, Pramod; Jodha, Ajay Singh; Misra, Manoj; Khatri, P.K.

2008-01-01

In nuclear hardened structures and AFV's, special shielding materials are being used to provide protection from radiations generated in nuclear blast. However, in blast an intense heat pulse is also generated along with radiation. Currently used shield does not take care of this heat pulse. Defence Laboratory, Jodhpur has developed multi transformation phase change materials (MTPCM) based cool panels for passive moderation of temperature in severe desert heat. The MTPCM contains light nuclei of hydrogen, carbon and oxygen, and thus can absorb good amount of neutrons. MTPCM can also absorb intense heat pulse along with heat generated by secondary fires during blast as its latent heat (160-170 J/g) without significant rise in temperature (melting point 36-38 deg. C). Thus MTPCM can provide protection against both radiation as well as heat pulse generated in a nuclear blast along with its designed regular function of passively moderating temperature below 40 deg C during severe desert summer. A study has been undertaken to explore multiple applications of MTPCM panel. Protection factor provided by standard MTPCM panels against neutron and gamma radiations (both initial and fall out) were measured and results compared with PF provided by special lining pad currently being used in AFV's and field structures for nuclear protection. It is observed that MTPCM provides good PF (2.17) against neutron which is better than currently used shield pads (PFP%1.8). Present paper discusses results of this study. (author)

The ATLAS SCT grounding and shielding concept and implementation

CERN Document Server

Bates, RL; Bernabeu, J; Bizzell, J; Bohm, J; Brenner, R; Bruckman de Renstrom, P A; Catinaccio, A; Cindro, V; Ciocio, A; Civera, J V; Chouridou, S; Dervan, P; Dick, B; Dolezal, Z; Eklund, L; Feld, L; Ferrere, D; Gadomski, S; Gonzalez, F; Gornicki, E; Greenhall, A; Grillo, A A; Grosse-Knetter, J; Gruwe, M; Haywood, S; Hessey, N P; Ikegami, Y; Jones, T J; Kaplon, J; Kodys, P; Kohriki, T; Kondo, T; Koperny, S; Lacasta, C; Lozano Bahilo, J; Malecki, P; Martinez-McKinney, F; McMahon, S J; McPherson, A; Mikulec, B; Mikus, M; Moorhead, G F; Morrissey, M C; Nagai, K; Nichols, A; O'Shea, V; Pater, J R; Peeters, S J M; Pernegger, H; Perrin, E; Phillips, P W; Pieron, J P; Roe, S; Sanchez, J; Spencer, E; Stastny, J; Tarrant, J; Terada, S; Tyndel, M; Unno, Y; Wallny, R; Weber, M; Weidberg, A R; Wells, P S; Werneke, P; Wilmut, I

2012-01-01

This paper describes the design and implementation of the grounding and shielding system for the ATLAS SemiConductor Tracker (SCT). The mitigation of electromagnetic interference and noise pickup through power lines is the critical design goal as they have the potential to jeopardize the electrical performance. We accomplish this by adhering to the ATLAS grounding rules, by avoiding ground loops and isolating the different subdetectors. Noise sources are identified and design rules to protect the SCT against them are described. A rigorous implementation of the design was crucial to achieve the required performance. This paper highlights the location, connection and assembly of the different components that affect the grounding and shielding system: cables, filters, cooling pipes, shielding enclosure, power supplies and others. Special care is taken with the electrical properties of materials and joints. The monitoring of the grounding system during the installation period is also discussed. Finally, after con...

Transparent fast neutron shielding material and shielding method

International Nuclear Information System (INIS)

Nashimoto, Tetsuji; Katase, Haruhisa.

1993-01-01

Polyisobutylene having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of greater than 7.0 x 10 22 /cm 3 is used as a fast neutron shielding material. The shielding material is excellent in the shielding performance against fast neutrons, and there is no worry of leakage even when holes should be formed to a vessel. Further, it is excellent in fabricability, relatively safe even upon occurrence of fire and, in addition, it is transparent to enable to observe contents easily. (T.M.)

Electromagnetically shielded building

Energy Technology Data Exchange (ETDEWEB)

Takahashi, T; Nakamura, M; Yabana, Y; Ishikawa, T; Nagata, K

1992-04-21

This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs.

Electromagnetically shielded building

International Nuclear Information System (INIS)

Takahashi, T.; Nakamura, M.; Yabana, Y.; Ishikawa, T.; Nagata, K.

1992-01-01

This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs

Radiation shielding concrete

International Nuclear Information System (INIS)

Kunishima, Shigeru.

1990-01-01

The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

Shielding augmentation of roll-on shield from NAPS to Kaiga-2

International Nuclear Information System (INIS)

Pradhan, A.S.; Kumar, A.N.

2000-01-01

Extensive radiation field surveys were conducted in NAPS and KAPS reactor buildings as a part of commissioning checks on radiation shielding. During such surveys, dose rate higher than the expected values were noticed in fuelling machine service areas. A movable shield, separating high field area fuelling machine vault and low field area fuelling machine service area, known as roll-on shield was identified as one of the causes of high field in fuelling machine service area along with weaker end-shield. This paper discusses systematic approach adopted in bringing down the dose rates in fuelling machine service area by augmentation of roll-on shield. (author)

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

Science.gov (United States)

Caputo, Fanny; de Nicola, Milena; Sienkiewicz, Andrzej; Giovanetti, Anna; Bejarano, Ignacio; Licoccia, Silvia; Traversa, Enrico; Ghibelli, Lina

2015-09-01

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields.

A Reinforcement for Multifunctional Composites for Non-Parasitic Radiation Shielding, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Radiation shielding is a requirement to protect humans from the hazards of space radiation during NASA missions. Multifunctional materials have the potential to...

One Year assessment of shielding for a multi-energy linear accelerator

International Nuclear Information System (INIS)

Lee, Jae Gi; Carlson, Joel; Lee, Hyun Seok; Ye, Sung Joon; Chung, Jin Beom; Kim, Jae Sung; Kim, Jung In

2014-01-01

In 2005, the publication of Report No. 151 of the National Council on Radiation Protection and Measurements (NCRP) suggested shielding methodologies along with shielding data. Recently, intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have become more widely used for cancer treatment. Thus, we analyzed shielding parameters for a multi-energy medical linear accelerator using the VMAT technique. Calculated total workload was similar to the recommendation of NCRP Report No. 49 and No. 51. However, these results were higher than the previous results in the NCRP Report No. 151. Also, the VMAT technique uses an intensity modulated beams with various gantry angles so that scattered and leakage doses should be carefully considered by retrospective analysis using the treatment data from each facility

One Year assessment of shielding for a multi-energy linear accelerator

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Gi; Carlson, Joel; Lee, Hyun Seok; Ye, Sung Joon [Seoul National University Graduate School of Convergence Science and Technology, Seoul (Korea, Republic of); Chung, Jin Beom; Kim, Jae Sung [Dept. of Radiation Oncology, Seoul National University Bundang Hospital, Seoul (Korea, Republic of); Kim, Jung In [Dept. of of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of)

2014-11-15

In 2005, the publication of Report No. 151 of the National Council on Radiation Protection and Measurements (NCRP) suggested shielding methodologies along with shielding data. Recently, intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have become more widely used for cancer treatment. Thus, we analyzed shielding parameters for a multi-energy medical linear accelerator using the VMAT technique. Calculated total workload was similar to the recommendation of NCRP Report No. 49 and No. 51. However, these results were higher than the previous results in the NCRP Report No. 151. Also, the VMAT technique uses an intensity modulated beams with various gantry angles so that scattered and leakage doses should be carefully considered by retrospective analysis using the treatment data from each facility.

Radiation shield analysis for a manned Mars rover

International Nuclear Information System (INIS)

Morley, N.J.; ElGenk, M.S.

1991-01-01

Radiation shielding for unmanned space missions has been extensively studied; however, designs of man-rated shields are minimal. Engle et al.'s analysis of a man-rated, multilayered shield composed of two and three cycles (a cycle consists of a tungsten and a lithium hydride layer) is the basis for the work reported in this paper. The authors present the results of a recent study of shield designs for a manned Mars rover powered by a 500-kW(thermal) nuclear reactor. A train-type rover vehicle was developed, which consists of four cars and is powered by an SP-100-type nuclear reactor heat source. The maximum permissible dose rate (MPD) from all sources is given by the National Council on Radiation Protection and Measurements as 500 mSv/yr (50 rem/yr) A 3-yr Mars mission (2-yr round trip and 1-yr stay) will deliver a 1-Sv natural radiation dose without a solar particle event, 450 mSv/yr in flight, and an additional 100 mSv on the planet surface. An anomalously large solar particle event could increase the natural radiation dose for unshielded astronauts on the Martian surface to 200 mSv. This limits the MPD to crew members from the nuclear reactor to 300 mSv

Benchmark analysis and evaluations of materials for shielding

International Nuclear Information System (INIS)

Benton, E.R.; Gersey, B.B.; Uchihori, Y.; Yasuda, N.; Kitamura, H.; Shavers, M.R.

2005-01-01

The goal of this project is to provide a benchmark set of heavy ion beam measurements behind ''standard'' targets made using radiation detectors routinely used for astronaut dosimetry and to test the radiation shielding properties of candidate multifunctional spacecraft materials. These measurements are used in testing and validating space radiation transport codes currently being developed by NASA and in selecting promising materials for further development. The radiation dosimetry instruments being used include CR-39 plastic nuclear track detector (PNTD), Tissue-Equivalent Proportional Counter (TEPC), the Liulin Mobile Dosimetry Unit (MDU) and thermoluminescent detector (TLD). Each set of measurements include LET/y spectra, and dose and dose equivalent as functions of shield thickness. Measurements are being conducted at the NIRS HIMAC, using heavy-ion beams of energy commonly encountered in the galactic cosmic ray (GCR) environment and that have been identified as being of particular concern to the radiation protection of space crews. Measurements are being made behind a set of standard'' targets including Al, Cu, polyethylene (HDPE) and graphite that vary in thickness from 0.5 to > 30 g/cm 2 . In addition, we are measuring the shielding properties of novel shielding materials being developed by and for NASA, including carbon and polymer composites. (author)

Comparison between Clinically Used Irregular Fields Shielded by Cerrobend and Standard Lead Blocks

Directory of Open Access Journals (Sweden)

Farajollahi A. R.

2015-06-01

Full Text Available Introduction: In radiation therapy centers across Iran, protection of normal tissues is usually accomplished by either Cerrobend or lead block shielding. In this study, the influence of these two shielding methods on central axis dose distribution of photon beam a Cobalt unit was investigated in clinical conditions. Materials and Methods: All measurements were performed for 60Co γ-ray beams and the Cerrobend blocks were fabricated by commercial Cerrobend materials. Standard lead block shields belonged to Cobalt unit. Data was collected through a calibrated ionization chamber, relative dosimetry systems and a TLD dosimetery. Results: Results of the percent depth dose (PDD measurements at depths of 0.5, 1, 5, 10, 15 and 20 cm for 23 different field sizes of patients with head and neck cancer showed no significant differences between lead and Cerrobend shielding methods. Measurement results of absolute dosimetry in depths of 1.5, 3, 5, 7, 10 and 12 cm also showed no significant differences between these two shielding methods. The same results were obtained by TLD dosimetry on patient skin. Conclusion: Use of melt shielding methods is a very easy and fast shield-making technique with no differences in PDD, absolute and skin dose between lead and Cerrobend block shielding methods.

Intrinsically disordered proteins as molecular shields.

Science.gov (United States)

Chakrabortee, Sohini; Tripathi, Rashmi; Watson, Matthew; Schierle, Gabriele S Kaminski; Kurniawan, Davy P; Kaminski, Clemens F; Wise, Michael J; Tunnacliffe, Alan

2012-01-01

The broad family of LEA proteins are intrinsically disordered proteins (IDPs) with several potential roles in desiccation tolerance, or anhydrobiosis, one of which is to limit desiccation-induced aggregation of cellular proteins. We show here that this activity, termed molecular shield function, is distinct from that of a classical molecular chaperone, such as HSP70 - while HSP70 reduces aggregation of citrate synthase (CS) on heating, two LEA proteins, a nematode group 3 protein, AavLEA1, and a plant group 1 protein, Em, do not; conversely, the LEA proteins reduce CS aggregation on desiccation, while HSP70 lacks this ability. There are also differences in interaction with client proteins - HSP70 can be co-immunoprecipitated with a polyglutamine-containing client, consistent with tight complex formation, whereas the LEA proteins can not, although a loose interaction is observed by Förster resonance energy transfer. In a further exploration of molecular shield function, we demonstrate that synthetic polysaccharides, like LEA proteins, are able to reduce desiccation-induced aggregation of a water-soluble proteome, consistent with a steric interference model of anti-aggregation activity. If molecular shields operate by reducing intermolecular cohesion rates, they should not protect against intramolecular protein damage. This was tested using the monomeric red fluorescent protein, mCherry, which does not undergo aggregation on drying, but the absorbance and emission spectra of its intrinsic fluorophore are dramatically reduced, indicative of intramolecular conformational changes. As expected, these changes are not prevented by AavLEA1, except for a slight protection at high molar ratios, and an AavLEA1-mCherry fusion protein is damaged to the same extent as mCherry alone. A recent hypothesis proposed that proteomes from desiccation-tolerant species contain a higher degree of disorder than intolerant examples, and that this might provide greater intrinsic stability

Radiation Exposure Analyses Supporting the Development of Solar Particle Event Shielding Technologies

Science.gov (United States)

Walker, Steven A.; Clowdsley, Martha S.; Abston, H. Lee; Simon, Hatthew A.; Gallegos, Adam M.

2013-01-01

NASA has plans for long duration missions beyond low Earth orbit (LEO). Outside of LEO, large solar particle events (SPEs), which occur sporadically, can deliver a very large dose in a short amount of time. The relatively low proton energies make SPE shielding practical, and the possibility of the occurrence of a large event drives the need for SPE shielding for all deep space missions. The Advanced Exploration Systems (AES) RadWorks Storm Shelter Team was charged with developing minimal mass SPE storm shelter concepts for missions beyond LEO. The concepts developed included "wearable" shields, shelters that could be deployed at the onset of an event, and augmentations to the crew quarters. The radiation transport codes, human body models, and vehicle geometry tools contained in the On-Line Tool for the Assessment of Radiation In Space (OLTARIS) were used to evaluate the protection provided by each concept within a realistic space habitat and provide the concept designers with shield thickness requirements. Several different SPE models were utilized to examine the dependence of the shield requirements on the event spectrum. This paper describes the radiation analysis methods and the results of these analyses for several of the shielding concepts.

Heavy density concrete for nuclear radiation shielding and power stations: [Part]2

International Nuclear Information System (INIS)

Singha Roy, P.K.

1987-01-01

This article is the second part of the paper entitled 'Heavy density concrete for nuclear radiation shielding and power stations'. In this part, some of the important properties of heavy density concrete are discussed. They include density, water retentivity, air content, permeability with special reference to concrete mixes used in India's nuclear power reactors. All these properties are affected to various extents by heating. Indian shield concrete is rarely subjected to temperatures above 60degC during its life, because of thermal shield protection. During placement, the maximum anticipated rise in temperature due to heat of hydration is restricted to around 45degC by chilling, if necessary to reduce shrinkage stresses and cracks. (M.G.B.)

Utilization of colemanite as a radiation protection material

International Nuclear Information System (INIS)

Bayulken, Ahmet; Aksut, Cem

1986-01-01

In experiments utilizing neutrons, a good shielding is very important. For developing countries, economics of the protection system is also a very important factor. In this work, a new material for protection blocks is investigated. These blocks are fabricated with colemanite powder in a paraffin wax matrix, and their behaviour as a neutron shield are investigated with a Pu-Be neutron source. (author)

Optimal beta-ray shielding thicknesses for different therapeutic radionuclides and shielding materials

International Nuclear Information System (INIS)

Cho, Yong In; Kim, Ja Mee; Kim, Jung Hoon

2017-01-01

To better understand the distribution of deposited energy of beta and gamma rays according to changes in shielding materials and thicknesses when radionuclides are used for therapeutic nuclear medicine, a simulation was conducted. The results showed that due to the physical characteristics of each therapeutic radionuclide, the thicknesses of shielding materials at which beta-ray shielding takes place varied. Additional analysis of the shielding of gamma ray was conducted for radionuclides that emit both beta and gamma rays simultaneously with results showing shielding effects proportional to the atomic number and density of the shielding materials. Also, analysis of bremsstrahlung emission after beta-ray interactions in the simulation revealed that the occurrence of bremsstrahlung was relatively lower than theoretically calculated and varied depending on different radionuclides. (authors)

Progress Toward Electrostatic Radiation Shielding of Interplanetary Spacecraft: Strategies, Concepts and Technical Challenges of Human Exploration Beyond Low Earth Orbit

Science.gov (United States)

Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.

2004-01-01

The radiation problem is a serious obstacle to solar system exploration. Electrostatic shielding was previously dismissed as unworkable. This was based on the false assumption that radial symmetry is needed to provide isotropic protection. KSC recently demonstrated the feasibility of asymmetric, multipole electrostatic shielding. Combined with passive shielding it might solve the radiation problem

Shielding properties of protective thin film coatings and blended concrete compositions for high level waste storage packages

International Nuclear Information System (INIS)

Fusco, Michael A.; Winfrey, Leigh; Bourham, Mohamed A.

2016-01-01

Highlights: • Measured linear attenuation coefficients are the same for bare and coated steels. • Gamma mean free path is much larger than coating thickness; buildup is negligible. • ‘Concrete-6’ reduces exposure rate outside spent fuel cask significantly over ordinary concrete. - Abstract: Various thin film coatings have been proposed to protect stainless steel high level waste (HLW) containers from premature failure due to localized corrosion, hydrogen embrittlement, and mechanical wear. These coatings include TiN, ZrO 2 , MoS 2 , TiO 2 , and Al 2 O 3 , to be deposited either in multiple layers or as a thicker, single-layer composite. Linear attenuation coefficients of these materials have been simulated using MicroShield and measured experimentally for various photon energies. Additionally, spent fuel casks with overpacks made of two different types of concrete were simulated to compare exposure rate at the cask surface. In the energy range that is significant for high level waste storage all coating materials possess very similar attenuation behavior. A specialty concrete, containing magnetite (Fe 3 O 4 ) and lead oxide (PbO), reduces the exposure rate at the outer surface of the overpack by several orders of magnitude. The higher-Z elements not present in ordinary concrete greatly increase attenuation of intermediate-energy gammas (0.4–1.0 MeV). The thin film coatings do not affect the shielding capabilities of the HLW packaging, as their total proposed thickness is nearly three orders of magnitude less than the mean free path (MFP) of the primary photons of interest.

Shielding Studies for Reducing the associated Radiological Risks Due To Irradiated Low Enriched Uranium Foil

International Nuclear Information System (INIS)

Margeanu, C.A.

2011-01-01

Present work estimates the radiation dose rates corresponding to irradiated Low Enriched Uranium (20 wt % 235 U) foil as part of shielding studies for radiological risks reduction after irradiation inside TRIGA 14 MW Research Reactor in an investigation on 99 Mo production possibility. Post-Irradiation Examination Laboratory's cell shielding calculations have been performed; radiation source was obtained by using ORIGEN-S code with specific cross-sections libraries. Different post-irradiation cooling times have been considered, gamma dose rates being estimated by using MAVRIC module from Scale 6 programs package, for following exposure situations (relative to Pie cell): i) front side, ii) lateral side and iii) back side. Three different calculations were performed: a) without any protection shield between operator and cell, except for the cell stainless steel wall; b) with a Lead protection shield between operator and cell and c) with a depleted Uranium shield, located inside the cell in between the radiation source and cell window. Radiation dose rates to cell external wall surface and for other eight fixed distances from cell wall were estimated. To obtain a consistent set of solutions, the study was done for various Uranium foil weights and different Lead and depleted Uranium shields thicknesses. Calculations were focused to assure that the dose rate to an operator positioned at 60 cm working distance from the cell will not exceed 0.02 mSv/h, maximum allowed dose rate for professionally exposed personnel according to Romanian regulations.

Studies of ionizing radiation shielding effectiveness of silica-based commercial glasses used in Bangladeshi dwellings

Directory of Open Access Journals (Sweden)

Sabina Yasmin

2018-06-01

Full Text Available Following the rapid growing economy, the Bangladeshi dwellers are replacing their traditional (mud-, bamboo-, and wood-based houses to modern multistoried buildings, where different types of glasses are being used as decorative as well as structural materials due to their various advantageous properties. In this study, we inquire the protective and dosimetric capability of commercial glasses for ionizing radiation. Four branded glass samples (PHP-Bangladesh, Osmania-Bangladesh, Nasir-Bangladesh, and Rider-China of same thickness and color but different elemental weight fractions were analyzed for shielding and dosimetric properties. The chemical composition of the studied material was evaluated by EDX technique. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the attenuation coefficients of the studied materials for 59 keV, 661 keV, 1173 keV and 1332 keV photon energies. A number of shielding parameters- half value layer (HVL, radiation protection efficiency (RPE and effective atomic number (Zeff were also evaluated. The data were compared with the available literature (where applicable to understand its shielding capability relative to the standard materials such as lead. Among the studied brands, Rider (China shows relatively better indices to be used as ionizing radiation shielding material. The obtained, Zeff of the studied glass samples showed comparable values to the TLD-200 dosimeter, thus considered suitable for environmental radiation monitoring purposes. Keywords: Silica-based commercial glass, HPGe γ-ray spectrometry, EDX analyses, Shielding effectiveness, Dosimetric properties

Protocol of source shielding maintenance in a level measurement systems

International Nuclear Information System (INIS)

Gonzales, E.; Figueroa, J.

1996-01-01

Maintenance labor of the source shielding and locking system is not performed in many Venezuelan enterprises that employ radioactive level gauge in large container. The lack of maintenance and the ambient long lasting action have produced impairment of many devices and their given parts rise to economical and radiological protection problems. In order to help to solve the mentioned problems, principally to reduce the unjustified dose to workers, the IVIC Health Physics Service worked out a protocol to perform, in a safety way, the maintenance of source shielding and its locking system. This protocol is presented in this paper. (authors)

E-Alerts: Nuclear science and technology (radiation shielding, protection, and safety). E-mail newsletter

International Nuclear Information System (INIS)

1999-01-01

Topics include: Shielding design, nuclear radiation transport properties of materials, decontamination; Container design and transportation requirements for radioactive materials; and Fallout shelters

The shielding calculation for the CN guide shielding assembly in HANARO

International Nuclear Information System (INIS)

Kim, H. S.; Lee, B. C.; Lee, K. H.; Kim, H.

2006-01-01

The cold neutron research facility in HANARO is under construction. The area including neutron guides and rotary shutter in the reactor hall should be shielded by the guide shielding assembly which is constructed of heavy concrete blocks and structure. The guide shielding assembly is divided into 2 parts, A and B. Part A is about 6.4 meters apart from the reactor biological shield and it is constructed of heavy concrete blocks whose density is above 4.0g/cm 3 . And part B is a fixed heavy concrete structure whose density is above 3.5g/cm 3 . The rotary shutter is also made with heavy concrete whose density is above 4.0g/cm 3 and includes 5 neutron guides inside. It can block the neutron beam by rotating when CNS is not operating. The dose criterion outside the guide shielding assembly is established as 12.5 μSv/hr which is also applied to reactor shielding in HANARO

INTOR radiation shielding for personnel access

International Nuclear Information System (INIS)

Gohar, Y.; Abdou, M.

1981-01-01

The INTOR reactor shield system consists of the blanket, bulk shield, penetration shield, component shield, and biological shield. The bulk shield consists of two parts: (a) the inboard shield; and (b) the outboard shield. The distinction between the different components of the shield system is essential to satisfy the different design constraints and achieve various objectives

Neutron shieldings

International Nuclear Information System (INIS)

Tarutani, Kohei

1979-01-01

Purpose: To decrease the stresses resulted by the core bendings to the base of an entrance nozzle. Constitution: Three types of round shielding rods of different diameter are arranged in a hexagonal tube. The hexagonal tube is provided with several spacer pads receiving the loads from the core constrain mechanism at its outer circumference, a handling head for a fuel exchanger at its top and an entrance nozzle for self-holding the neutron shieldings and flowing heat-removing coolants at its bottom. The diameters for R 1 , R 2 and R 3 for the round shielding rods are designed as: 0.1 R 1 2 1 and 0.2 R 1 2 1 . Since a plurality of shielding rods of small diameter are provided, soft structure are obtained and a plurality of coolant paths are formed. (Furukawa, Y.)

Comparison of eye shields in radiotherapeutic beams

International Nuclear Information System (INIS)

Currie, B.E.; Wellington Hospital, Wellington; Johnson, A.D.

2004-01-01

Full text: Both MeV electrons and kV photons are used in the treatment of superficial cancers. The advantages and disadvantages for each of these modalities have been widely reported in the literature (See for example [1-2]). Of particular note in the literature is the use of lead and tungsten eye shields to protect ocular structures during radiotherapy. An investigation addressing issues raised in the literature that are relevant to the Wellington Cancer Centre method of treatment of lesions near the eye shall be summarised. Various small sized fields were irradiated to determine depth dose and profile curves in a water phantom shielded by various commercially available eye shields. Transmission factors relevant to critical ocular structures and particle distribution theories are used to further elucidate the comparison between the use of MeV electrons and kV photons in the treatment of superficial cancers. Superficial X-rays from a Pantak Therapax unit SXT 150 model of HVL 4.90mm Al were used for the lead eye shield measurements and electrons from a Varian Clinac 2100C nominal energies 6MeV and 9MeV (R p 3.00cm and 4.34cm respectively) were used for the tungsten eye shield measurements. For the photon measurements circular applicators of 3cm, 4cm and 5cm diameter were used and for the electrons standard 6x6cm and 10x 10cm applicators were used, with no custom inserts. A Scanditronix RFA-300 water phantom and Scanditronix RFAplus version 5.3 software application were used to collect and collate all data. The eye shields were the Radiation Products Design Inc. medium lead eye shield (item 934-014) and the MED-TEC tungsten eye shields MT-T-45 M and MT-T-45 S. It is demonstrated that electron fields have appreciably greater scatter into the area directly under the eye shields than the photon fields. Similarly at the region of d max for the electron fields the relative dose is appreciably greater than the photon fields at similar depth. The relative merits for

PMMA/MWCNT nanocomposite for proton radiation shielding applications

Science.gov (United States)

Li, Zhenhao; Chen, Siyuan; Nambiar, Shruti; Sun, Yonghai; Zhang, Mingyu; Zheng, Wanping; Yeow, John T. W.

2016-06-01

Radiation shielding in space missions is critical in order to protect astronauts, spacecraft and payloads from radiation damage. Low atomic-number materials are efficient in shielding particle-radiation, but they have relatively weak material properties compared to alloys that are widely used in space applications as structural materials. However, the issues related to weight and the secondary radiation generation make alloys not suitable for space radiation shielding. Polymers, on the other hand, can be filled with different filler materials for reinforcement of material properties, while at the same time provide sufficient radiation shielding function with lower weight and less secondary radiation generation. In this study, poly(methyl-methacrylate)/multi-walled carbon nanotube (PMMA/MWCNT) nanocomposite was fabricated. The role of MWCNTs embedded in PMMA matrix, in terms of radiation shielding effectiveness, was experimentally evaluated by comparing the proton transmission properties and secondary neutron generation of the PMMA/MWCNT nanocomposite with pure PMMA and aluminum. The results showed that the addition of MWCNTs in PMMA matrix can further reduce the secondary neutron generation of the pure polymer, while no obvious change was found in the proton transmission property. On the other hand, both the pure PMMA and the nanocomposite were 18%-19% lighter in weight than aluminum for stopping the protons with the same energy and generated up to 5% fewer secondary neutrons. Furthermore, the use of MWCNTs showed enhanced thermal stability over the pure polymer, and thus the overall reinforcement effects make MWCNT an effective filler material for applications in the space industry.

Radiation Protection and Architecture Utilizing High Temperature Superconducting Magnets

Data.gov (United States)

National Aeronautics and Space Administration — This study will explore the effectiveness of using electromagnets to protect a habitat from radiation through active radiation shielding.Active radiation shielding...

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

KAUST Repository

Caputo, Fanny

2015-08-20

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields. © The Royal Society of Chemistry 2015.

Radiation shielding plate

International Nuclear Information System (INIS)

Kobayashi, Torakichi; Sugawara, Takeo.

1983-01-01

Purpose: To reduce the weight and stabilize the configuration of a radiation shielding plate which is used in close contact with an object to be irradiated with radiation rays. Constitution: The radiation shielding plate comprises a substrate made of lead glass and a metallic lead coating on the surface of the substrate by means of plating, vapor deposition or the like. Apertures for permeating radiation rays are formed to the radiation shielding plate. Since the shielding plate is based on a lead glass plate, a sufficient mechanical strength can be obtained with a thinner structure as compared with the conventional plate made of metallic lead. Accordingly, if the shielding plate is disposed on a soft object to be irradiated with radiation rays, the object and the plate itself less deform to obtain a radiation irradiation pattern with distinct edges. (Moriyama, K.)

Infinite slab-shield dose calculations

International Nuclear Information System (INIS)

Russell, G.J.

1989-01-01

I calculated neutron and gamma-ray equivalent doses leaking through a variety of infinite (laminate) slab-shields. In the shield computations, I used, as the incident neutron spectrum, the leakage spectrum (<20 MeV) calculated for the LANSCE tungsten production target at 90 degree to the target axis. The shield thickness was fixed at 60 cm. The results of the shield calculations show a minimum in the total leakage equivalent dose if the shield is 40-45 cm of iron followed by 20-15 cm of borated (5% B) polyethylene. High-performance shields can be attained by using multiple laminations. The calculated dose at the shield surface is very dependent on shield material. 4 refs., 4 figs., 1 tab

Journalists' Privilege to Withhold Information in Judicial and Other Proceedings: State Shield Statutes

National Research Council Canada - National Science Library

Cohen, Henry

2007-01-01

.... To date, 33 states and the District of Columbia have recognized a journalists' privilege through the enactment of press "shield laws," which protect the relationship between reporters, their source...

Electromagnetic shield

International Nuclear Information System (INIS)

Miller, J.S.

1987-01-01

An electromagnetic shield is described comprising: closed, electrically-conductive rings, each having an open center; and binder means for arranging the rings in a predetermined, fixed relationship relative to each other, the so-arranged rings and binder means defining an outer surface; wherein electromagnetic energy received by the shield from a source adjacent its outer surface induces an electrical current to flow in a predetermined direction adjacent and parallel to the outer surface, through the rings; and wherein each ring is configured to cause source-induced alternating current flowing through the portion of the ring closest to the outer surface to electromagnetically induce an oppositely-directed current in the portion of the ring furthest from the surface, such oppositely-directed current bucking any source-induced current in the latter ring portion and thus reducing the magnitude of current flowing through it, whereby the electromagnetic shielding effected by the shield is enhanced

Development of Point Kernel Shielding Analysis Computer Program Implementing Recent Nuclear Data and Graphic User Interfaces

International Nuclear Information System (INIS)

Kang, Sang Ho; Lee, Seung Gi; Chung, Chan Young; Lee, Choon Sik; Lee, Jai Ki

2001-01-01

In order to comply with revised national regulationson radiological protection and to implement recent nuclear data and dose conversion factors, KOPEC developed a new point kernel gamma and beta ray shielding analysis computer program. This new code, named VisualShield, adopted mass attenuation coefficient and buildup factors from recent ANSI/ANS standards and flux-to-dose conversion factors from the International Commission on Radiological Protection (ICRP) Publication 74 for estimation of effective/equivalent dose recommended in ICRP 60. VisualShield utilizes graphical user interfaces and 3-D visualization of the geometric configuration for preparing input data sets and analyzing results, which leads users to error free processing with visual effects. Code validation and data analysis were performed by comparing the results of various calculations to the data outputs of previous programs such as MCNP 4B, ISOSHLD-II, QAD-CGGP, etc

Ductile iron cask with encapsulated uranium, tungsten or other dense metal shielding

International Nuclear Information System (INIS)

Barnhart, V.J.; Anderson, R.T.

1989-01-01

In a cask for the transportation and storage of radioactive materials, an improvement in the shielding means which achieves significant savings in weight and increases in payload by the use of pipes of depleted uranium, tungsten or other dense metal, encapsulating polyethylene cores, dispersed in two to four rows of concentric boreholes around the periphery of the cask body which is preferably made of ductile iron. Alternatively, rods or small balls of these same shielding materials, alone or in combination, are placed in these bore holes. The thickness, number and arrangement of these shielding pipes or rods is varied to provide optimum protection against the neutrons and gamma radiation emitted by the particular radioactive material being transported or stored. (author) 4 figs

Studies of ionizing radiation shielding effectiveness of silica-based commercial glasses used in Bangladeshi dwellings

Science.gov (United States)

Yasmin, Sabina; Barua, Bijoy Sonker; Khandaker, Mayeen Uddin; Chowdhury, Faruque-Uz-Zaman; Rashid, Md. Abdur; Bradley, David A.; Olatunji, Michael Adekunle; Kamal, Masud

2018-06-01

Following the rapid growing economy, the Bangladeshi dwellers are replacing their traditional (mud-, bamboo-, and wood-based) houses to modern multistoried buildings, where different types of glasses are being used as decorative as well as structural materials due to their various advantageous properties. In this study, we inquire the protective and dosimetric capability of commercial glasses for ionizing radiation. Four branded glass samples (PHP-Bangladesh, Osmania-Bangladesh, Nasir-Bangladesh, and Rider-China) of same thickness and color but different elemental weight fractions were analyzed for shielding and dosimetric properties. The chemical composition of the studied material was evaluated by EDX technique. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the attenuation coefficients of the studied materials for 59 keV, 661 keV, 1173 keV and 1332 keV photon energies. A number of shielding parameters- half value layer (HVL), radiation protection efficiency (RPE) and effective atomic number (Zeff) were also evaluated. The data were compared with the available literature (where applicable) to understand its shielding capability relative to the standard materials such as lead. Among the studied brands, Rider (China) shows relatively better indices to be used as ionizing radiation shielding material. The obtained, Zeff of the studied glass samples showed comparable values to the TLD-200 dosimeter, thus considered suitable for environmental radiation monitoring purposes.

Comparison of different methods for shielding design in computed tomography

International Nuclear Information System (INIS)

Ciraj-Bjelac, O.; Arandjic, D.; Kosutic, D.

2011-01-01

The purpose of this work is to compare different methods for shielding calculation in computed tomography (CT). The BIR-IPEM (British Inst. of Radiology and Inst. of Physics in Engineering in Medicine) and NCRP (National Council on Radiation Protection) method were used for shielding thickness calculation. Scattered dose levels and calculated barrier thickness were also compared with those obtained by scatter dose measurements in the vicinity of a dedicated CT unit. Minimal requirement for protective barriers based on BIR-IPEM method ranged between 1.1 and 1.4 mm of lead demonstrating underestimation of up to 20 % and overestimation of up to 30 % when compared with thicknesses based on measured dose levels. For NCRP method, calculated thicknesses were 33 % higher (27-42 %). BIR-IPEM methodology-based results were comparable with values based on scattered dose measurements, while results obtained using NCRP methodology demonstrated an overestimation of the minimal required barrier thickness. (authors)

Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

International Nuclear Information System (INIS)

Abulfaraj, W.H.; Kamal, S.M.

1994-01-01

The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concrete shielding. Multiattribute utility theory is selected to accommodate decision maker's preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Illmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy weight heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Illmenite Serpentine concrete. (Author)

Shielding Calculations for PUSPATI TRIGA Reactor (RTP) Fuel Transfer Cask with Micro shield

International Nuclear Information System (INIS)

Nurhayati Ramli; Ahmad Nabil Abdul Rahim; Ariff Shah Ismail

2011-01-01

The shielding calculations for RTP fuel transfer cask was performed by using computer code Micro shield 7.02. Micro shield is a computer code designed to provide a model to be used for shielding calculations. The results of the calculations can be obtained fast but the code is not suitable for complex geometries with a shielding composed of more than one material. Nevertheless, the program is sufficient for As Low As Reasonable Achievable (ALARA) optimization calculations. In this calculation, a geometry based on the conceptual design of RTP fuel transfer cask was modeled. Shielding material used in the calculations were lead (Pb) and stainless steel 304 (SS304). The results obtained from these calculations are discussed in this paper. (author)

The Active Muon Shield

CERN Document Server

Bezshyiko, Iaroslava

2016-01-01

In the SHiP beam-dump of the order of 1011 muons will be produced per second. An active muon-shield is used to magnetically deflect these muons out of the acceptance of the spectrom- eter. This note describes how this shield is modelled and optimized. The SHiP spectrometer is being re-optimized using a conical decay-vessel, and utilizing the possibility to magnetize part of the beam-dump shielding iron. A shield adapted to these new conditions is presented which is significantly shorter and lighter than the shield used in the Technical Proposal (TP), while showing a similar performance.

Principles of Radiation Protection Concepts

International Nuclear Information System (INIS)

Abd Aziz Mhd Ramli

2004-01-01

The contents of this chapter are follows - Radiation Protection Concepts: justification, dose limitation, optimisation, potential exposures, situation requiring intervention; Special Considerations. Protection from Radiation Hazards, Remove the Hazard, Prevent the Hazard, Guard the Worker, Implementation of Radiation Protection and Safety Measures, Distance, Shielding, Time, Monitoring Programme, Safety System. Radiation Protection in Radiological Service: Specific Requirement in Diagnostic Radiological Service

REACTOR SHIELD

Science.gov (United States)

Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

1959-02-17

Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

Radiation protection for human missions to the Moon and Mars

International Nuclear Information System (INIS)

Simonsen, L.C.; Nealy, J.E.

1991-02-01

Radiation protection assessments are performed for advanced Lunar and Mars manned missions. The Langley cosmic ray transport code and the nucleon transport code are used to quantify the transport and attenuation of galactic cosmic rays and solar proton flares through various shielding media. Galactic cosmic radiation at solar maximum and minimum, as well as various flare scenarios are considered. Propagation data for water, aluminum, liquid hydrogen, lithium hydride, lead, and lunar and Martian regolith (soil) are included. Shield thickness and shield mass estimates required to maintain incurred doses below 30 day and annual limits (as set for Space Station Freedom and used as a guide for space exploration) are determined for simple geometry transfer vehicles. On the surface of Mars, dose estimates are presented for crews with their only protection being the carbon dioxide atmosphere and for crews protected by shielding provided by Martian regolith for a candidate habitat

Safety and shielding management for pulse power lab at IPR

International Nuclear Information System (INIS)

Upadhyay, Shweta; Faldu, Akash; Koshti, Rahul; Kumar, Rajesh

2016-01-01

Experiments in pulsed power lab works with very high voltage and high current regime for the nanosecond to microsecond time scale. This produces lot of electromagnetic noise, which can cause interference or malfunctioning of equipment. Laboratory Safety and protection are a very important aspect of science and engineering. Without it, practical performance could result in very serious injury, if not death. To reduce its effect electromagnetic shielding and grounding has to be enforced effectively. Pulse power lab deals with many safety issues like Radiation safety (shielding), High voltage safety, electrical and mechanical safety, etc. In this paper radiation all the safety aspects in pulse power lab is described. (author)

Neutron shielding behavior of thermoplastic natural rubber/boron carbide composites

Science.gov (United States)

Mat Zali, Nurazila; Yazid, Hafizal; Megat Ahmad, Megat Harun Al Rashid

2018-01-01

Many shielding materials have been designed against the harm of different types of radiation to the human body. Today, polymer-based lightweight composites have been chosen by the radiation protection industry. In the present study, thermoplastic natural rubber (TPNR) composites with different weight percent of boron carbide (B4C) fillers (0% to 30%) were fabricated as neutron shielding through melt blending method. Neutron attenuation properties of TPNR/B4C composites have been investigated. The macroscopic cross section (Σ), half value layer (HVL) and mean free path length (λ) of the composites have been calculated and the transmission curves have been plotted. The obtained results show that Σ, HVL and λ greatly depend on the B4C content. Addition of B4C fillers into TPNR matrix were found to enhance the macroscopic cross section values thus decrease the mean free path length (λ) and half value layer (HVL) of the composites. The transmission curves exhibited that the neutron transmission of the composites decreased with increasing shielding thickness. These results showed that TPNR/B4C composites have high potential for neutron shielding applications.

Design of emergency shield

International Nuclear Information System (INIS)

Soliman, S.E.

1993-01-01

Manufacturing of an emergency movable shield in the hot laboratories center is urgently needed for the safety of personnel in case of accidents or spilling of radioactive materials. In this report, a full design for an emergency shield is presented and the corresponding dose rates behind the shield for different activities (from 1 mCi to 5 Ci) was calculated by using micro shield computer code. 4 figs., 1 tab

RadShield: semiautomated shielding design using a floor plan driven graphical user interface.

Science.gov (United States)

DeLorenzo, Matthew C; Wu, Dee H; Yang, Kai; Rutel, Isaac B

2016-09-08

The purpose of this study was to introduce and describe the development of RadShield, a Java-based graphical user interface (GUI), which provides a base design that uniquely performs thorough, spatially distributed calculations at many points and reports the maximum air-kerma rate and barrier thickness for each barrier pursuant to NCRP Report 147 methodology. Semiautomated shielding design calculations are validated by two approaches: a geometry-based approach and a manual approach. A series of geometry-based equations were derived giv-ing the maximum air-kerma rate magnitude and location through a first derivative root finding approach. The second approach consisted of comparing RadShield results with those found by manual shielding design by an American Board of Radiology (ABR)-certified medical physicist for two clinical room situations: two adjacent catheterization labs, and a radiographic and fluoroscopic (R&F) exam room. RadShield's efficacy in finding the maximum air-kerma rate was compared against the geometry-based approach and the overall shielding recommendations by RadShield were compared against the medical physicist's shielding results. Percentage errors between the geometry-based approach and RadShield's approach in finding the magnitude and location of the maximum air-kerma rate was within 0.00124% and 14 mm. RadShield's barrier thickness calculations were found to be within 0.156 mm lead (Pb) and 0.150 mm lead (Pb) for the adjacent catheteriza-tion labs and R&F room examples, respectively. However, within the R&F room example, differences in locating the most sensitive calculation point on the floor plan for one of the barriers was not considered in the medical physicist's calculation and was revealed by the RadShield calculations. RadShield is shown to accurately find the maximum values of air-kerma rate and barrier thickness using NCRP Report 147 methodology. Visual inspection alone of the 2D X-ray exam distribution by a medical physicist may not

Challenges in commercial manufacture of radiation shielding glasses

International Nuclear Information System (INIS)

Gupta, R.K.

2011-01-01

Radioactive hot-cells employ Radiation Shielding Windows (RSWs), assembled from specialty glasses, developed exclusively for nuclear industry. RSWs serve the twin purpose of direct viewing and shielding protection to the operator and use various types of radiation resistant and optically compatible glasses, such as low-density borosilicate glass; medium-density glass with up to 45% Lead and high-density glass with over 70% lead. Some glasses are Ceria-doped for enhancing their resistance threshold to radiation browning. A clear view of future requirement, capital and environmental costs could be the driving force towards bringing about changes in melting practices, encourage melting development, and enhancing collaboration. With DAE and CGCRI working in tandem, production of the entire range of RSW glasses by an Indian glass industry participant may no longer be a distant dream

Topics in radiation at accelerators: Radiation physics for personnel and environmental protection

International Nuclear Information System (INIS)

Cossairt, J.D.

1993-11-01

This report discusses the following topics: Composition of Accelerator Radiation Fields; Shielding of Electrons and Photons at Accelerators; Shielding of Hadrons at Accelerators; Low Energy Prompt Radiation Phenomena; Induced Radioactivity at Accelerators; Topics in Radiation Protection Instrumentation at Accelerators; and Accelerator Radiation Protection Program Elements

Neutron shielding material

International Nuclear Information System (INIS)

Nodaka, M.; Iida, T.; Taniuchi, H.; Yosimura, K.; Nagahama, H.

1993-01-01

From among the neutron shielding materials of the 'kobesh' series developed by Kobe Steel, Ltd. for transport and storage packagings, silicon rubber base type material has been tested for several items with a view to practical application and official authorization, and in order to determine its adaptability to actual vessels. Silicon rubber base type 'kobesh SR-T01' is a material in which, from among the silicone rubber based neutron shielding materials, the hydrogen content is highest and the boron content is most optimized. Its neutron shielding capability has been already described in the previous report (Taniuchi, 1986). The following tests were carried out to determine suitability for practical application; 1) Long-term thermal stability test 2) Pouring test on an actual-scale model 3) Fire test The experimental results showed that the silicone rubber based neutron shielding material has good neutron shielding capability and high long-term fire resistance, and that it can be applied to the advanced transport packaging. (author)

Development and production of radiation shielding window (RSW) glass: Indian scenario

International Nuclear Information System (INIS)

Phani, K.K.

2006-01-01

Nuclear energy/power and its peaceful applications play an ever increasing role in India. Irradiated nuclear fuels, irradiated structural materials from reactors, nuclear wastes and radio-isotopes emit high energy gamma radiations which are extremely health hazardous. These materials are handled remotely by manipulators inside the hot cells, which are constructed by shielding materials such as lead and concrete walls. The direct visual control of processes in the hot cells during operation demands the windows in the radiation shielding walls. These windows must provide the clear viewing but yet ensure the good protection to the working personnel from the high energy radiation

Shielding benchmark problems, (2)

International Nuclear Information System (INIS)

Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Shin, Kazuo; Tada, Keiko.

1980-02-01

Shielding benchmark problems prepared by Working Group of Assessment of Shielding Experiments in the Research Committee on Shielding Design in the Atomic Energy Society of Japan were compiled by Shielding Laboratory in Japan Atomic Energy Research Institute. Fourteen shielding benchmark problems are presented newly in addition to twenty-one problems proposed already, for evaluating the calculational algorithm and accuracy of computer codes based on discrete ordinates method and Monte Carlo method and for evaluating the nuclear data used in codes. The present benchmark problems are principally for investigating the backscattering and the streaming of neutrons and gamma rays in two- and three-dimensional configurations. (author)

Protecting Spacecraft Fragments from Exposure to Small Debris

Directory of Open Access Journals (Sweden)

V. V. Zelentsov

2015-01-01

Full Text Available Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable debris. In case of possible collision with the observed debris an avoidance manoeuvre is provided. The situation with unobservable debris is worse, its dimensions ranging from 100 mm to several microns. This debris is formed as a result of explosions of dead space objects and at collisions of destroyed spacecraft fragments against each other. This debris moves along arbitrary trajectories at different speeds.At collision of a spacecraft with fragments of small-size space debris, various consequences are possible: the device can immediately fail, suffer damages, which will have effect later and damages, which break no bones to the aircraft. Anyway, the spacecraft collision with small-size debris particles is undesirable. The protective shields are used to protect the aircraft from damage. Development of shield construction is complicated because the high cost of launch makes it impossible to conduct field tests of shields in space. All the work is carried out in the laboratory, with particles having co-impact speeds up to 10 km/s (possible speeds are up to 20 km/s and spherically shaped particles of 0.8 ... 3 mm in diameter.Various materials are used to manufacture shields. These are aluminum sheet, sandwich panels, metal mesh, metal foam, and woven materials (ballistic fabric. The paper considers single-layer (from sheet metal sandwich materials and multilayer shield designs. As experimental studies show, a single-layer shield protects colliding at speeds

Primary shield displacement and bowing

International Nuclear Information System (INIS)

Scott, K.V.

1978-01-01

The reactor primary shield is constructed of high density concrete and surrounds the reactor core. The inlet, outlet and side primary shields were constructed in-place using 2.54 cm (1 in) thick steel plates as the forms. The plates remained as an integral part of the shields. The elongation of the pressure tubes due to thermal expansion and pressurization is not moving through the inlet nozzle hardware as designed but is accommodated by outward displacement and bowing of the inlet and outlet shields. Excessive distortion of the shields may result in gas seal failures, intolerable helium gas leaks, increased argon-41 emissions, and shield cooling tube failures. The shield surveillance and testing results are presented

Evaluation of the shielding integrity of end-shields in PHWR type NPPs

International Nuclear Information System (INIS)

Sah, B.M.L.; Ramamirtham, B.; Kutty, B.S.

1996-01-01

In the new plants (Narora Atomic Power Plants (NAPP) onwards) relatively higher radiation fields exist on the north and south fuelling machine (FM) vault walls of the E1 100m accessible area passages. These fields were first noticed at NAPS-1 and subsequently at NAPS-2 and KAPS-1. Such surveys done at RAPS have indicated that the fields on these walls would come out to be quite low (only 1-2 mR/h) from sources other than that arising from 41 Ar contamination. RAPS/MAPS experience pointed to adequacy of shielding of the FM vault walls and sufficient overall shielding thickness of the end-shields. Further, radiometry tests of end-shields carried out at Kaiga and RAPP 3 and 4 indicated fairly satisfactory and uniform filling of balls. Hence, incomplete filling of water column of the end-shields due to any venting problem was suspected to be one possible reason for the observed high fields in NAPS and Kakrapar Atomic Power Station (KAPS). Since the presence of high radiation fields, both neutron and gamma, is of long-term concern, a special study/measurement of radiation levels on reactor face during high power operation was undertaken. In order to compare the shielding integrity of the older (RAPS/MAPS solid plate type shielding) and newer (NAPS/KAPS steel ball-filled type) end shields, these experiments were done at MAPS-2 and NAPS-2. (author). 2 refs., 2 tabs

Protection of persons undergoing radiological examinations ...

African Journals Online (AJOL)

Protection was in the form of gonad shields, lead apron to shield the unwanted parts during examinations and coning the X-ray field before exposure. The staff had Thermoluminscent Dosimeters (TLD) to monitor dose levels received by such staff every three months. They wore hand gloves, lead aprons and stayed behind ...

Magnetic shielding for superconducting RF cavities

Science.gov (United States)

Masuzawa, M.; Terashima, A.; Tsuchiya, K.; Ueki, R.

2017-03-01

Magnetic shielding is a key technology for superconducting radio frequency (RF) cavities. There are basically two approaches for shielding: (1) surround the cavity of interest with high permeability material and divert magnetic flux around it (passive shielding); and (2) create a magnetic field using coils that cancels the ambient magnetic field in the area of interest (active shielding). The choice of approach depends on the magnitude of the ambient magnetic field, residual magnetic field tolerance, shape of the magnetic shield, usage, cost, etc. However, passive shielding is more commonly used for superconducting RF cavities. The issue with passive shielding is that as the volume to be shielded increases, the size of the shielding material increases, thereby leading to cost increase. A recent trend is to place a magnetic shield in a cryogenic environment inside a cryostat, very close to the cavities, reducing the size and volume of the magnetic shield. In this case, the shielding effectiveness at cryogenic temperatures becomes important. We measured the permeabilities of various shielding materials at both room temperature and cryogenic temperature (4 K) and studied shielding degradation at that cryogenic temperature.

Elevated gamma-rays shielding property in lead-free bismuth tungstate by nanofabricating structures

Science.gov (United States)

Liu, Jun-Hua; Zhang, Quan-Ping; Sun, Nan; Zhao, Yang; Shi, Rui; Zhou, Yuan-Lin; Zheng, Jian

2018-01-01

Radiation shielding materials have attracted much attention across academia and industry because of the increasing of nuclear activities. To achieve the materials with low toxicity but good protective capability is one of the most significant goals for personal protective articles. Here, bismuth tungstate nanostructures are controllably fabricated by a versatile hydrothermal treatment under various temperatures. The crystals structure and morphology of products are detailedly characterized with X-ray diffraction, electron microscope and specific surface area. It is noteworthy that desired Bi2WO6 nanosheets treated with 190 °C show the higher specific surface area (19.5 m2g-1) than that of the other two products. Importantly, it has a close attenuating property to lead based counterpart for low energy gamma-rays. Due to the less toxicity, Bi2WO6 nanosheets are more suitable than lead based materials to fabricate personal protective articles for shielding low energy radiations and have great application prospect as well as market potential.

Mini-chamber, an advanced protection concept for NIF

International Nuclear Information System (INIS)

Peterson, P.F.; Scott, J.M.

1996-01-01

Inertial confinement fusion (ICF) target debris and ablated near-target materials pose the primary threat to the National Ignition Facility (NIF) final optics debris shields, as well as a major challenge in future inertial fusion energy (IFE) power plants. This work discusses a NIF 'mini-chamber,' designed to mitigate the debris threat. Although the NIF base-line design protects against debris using a frost-protected target positioner and refractory first-wall coatings, the mini-chamber provides important flexibility in three areas: debris-shield protection from beyond-design basis shots (i.e. heavy hohlraums, special diagnostics, shields); fielding of large experiments with significant surface ablation; and studying key ablation and gas-dynamics issues for liquid-wall IFE power plants. Key mini-chamber modeling results are presented, followed by discussion of equipment requirements for fielding a NIF mini-chamber. 7 refs., 3 figs

Design of a PET/CT facility considering the shielding calculation in accordance with AAPM TG-108

International Nuclear Information System (INIS)

Guevara R, V. Y.; Romero C, N.; Berrocal T, M.

2014-08-01

A Positron Emission Tomography / Computed Tomography facility may require protection barriers on floor, ceiling and walls, because the patient becomes a radioactive source that emits photons of 0.511 MeV, after having received a radiopharmaceutical, usually F-18 fluorodeoxyglucose (F-18 FDG). This work has as objective to propose the design of a PET/CT facility, taking into account technical and radiation protection considerations applied internationally, and also develop the necessary shielding for such installation by applying as published by the American Association of Physicists in Medicine Task Group Report 108. A shielding spreadsheet in Excel program was developed with reference to the recommendations of the AAPM TG - 08, to determine the shielding required for the walls, floor and ceiling. For fixing the radiation levels in the shielding calculation has been considered the actual restrictions for the occupationally exposed personnel (100 μSv/week) as well as the people in general (20 μSv/ week). The radiopharmaceutical used as a reference for the shielding calculation was the F-18 FDG. With the assistance of an architectural plan were determined distances from potential sources of radiation in facility (uptake and image acquisition living rooms) to points of interest around them. Finally the thickness of the protective barriers in lead and concrete necessary to achieve the established radiation levels were calculated and these results were stored in a table. This paper shows that technical aspects considered in the design of the installation and environments distribution can improve work processes within the PET/CT facility, consequently resulting in a reduction of the dose levels for people in general. (author)

Efficacy of face shields against cough aerosol droplets from a cough simulator.

Science.gov (United States)

Lindsley, William G; Noti, John D; Blachere, Francoise M; Szalajda, Jonathan V; Beezhold, Donald H

2014-01-01

Health care workers are exposed to potentially infectious airborne particles while providing routine care to coughing patients. However, much is not understood about the behavior of these aerosols and the risks they pose. We used a coughing patient simulator and a breathing worker simulator to investigate the exposure of health care workers to cough aerosol droplets, and to examine the efficacy of face shields in reducing this exposure. Our results showed that 0.9% of the initial burst of aerosol from a cough can be inhaled by a worker 46 cm (18 inches) from the patient. During testing of an influenza-laden cough aerosol with a volume median diameter (VMD) of 8.5 μm, wearing a face shield reduced the inhalational exposure of the worker by 96% in the period immediately after a cough. The face shield also reduced the surface contamination of a respirator by 97%. When a smaller cough aerosol was used (VMD = 3.4 μm), the face shield was less effective, blocking only 68% of the cough and 76% of the surface contamination. In the period from 1 to 30 minutes after a cough, during which the aerosol had dispersed throughout the room and larger particles had settled, the face shield reduced aerosol inhalation by only 23%. Increasing the distance between the patient and worker to 183 cm (72 inches) reduced the exposure to influenza that occurred immediately after a cough by 92%. Our results show that health care workers can inhale infectious airborne particles while treating a coughing patient. Face shields can substantially reduce the short-term exposure of health care workers to large infectious aerosol particles, but smaller particles can remain airborne longer and flow around the face shield more easily to be inhaled. Thus, face shields provide a useful adjunct to respiratory protection for workers caring for patients with respiratory infections. However, they cannot be used as a substitute for respiratory protection when it is needed. [Supplementary materials are

Assessment of radiation protection practices among radiographers ...

African Journals Online (AJOL)

Application of shielding devices such as gonad shield for protection was neglected mostly in government hospitals. Most x-ray machines were quite old and evidence of quality assurance tests performed on such machines were lacking. Conclusion: Radiographers within Lagos metropolis showed an excellent knowledge of ...

Protecting sources: from shield laws to Wikileaks

Directory of Open Access Journals (Sweden)

Mélanie Dupéré

2015-09-01

Full Text Available This paper focuses on recent developments in the right and ability of journalists to protect their sources’ anonymity in the United Kingdom, particularly in light of the Snowden revelations of June 2013, and the significance of collaboration between the global online media organization Wikileaks and mainstream news organisations. It explores two key difficulties faced by journalists: the notion of a qualified professional privilege and the unknown extent of covert requests by public authorities for disclosure involving communications data and metadata. In doing so, it comments upon the opening filled by Wikileaks, which protects its sources’ anonymity through high data security and encryption. This paper’s findings tend to show that the covert practice of blanket mass digital surveillance of individual communications including journalists’ is undermining source protection and the rise of Wikileaks as an alternative model is challenging the traditional role of journalists as mediators and gatekeepers in the digital era.

Nuclear power plant component protection

International Nuclear Information System (INIS)

Michel, E.; Ruf, R.; Dorner, H.

1976-01-01

Described is a nuclear power plant installation which includes a concrete biological shield forming a pit in which a reactor pressure vessel is positioned. A steam generator on the outside of the shield is connected with the pressure vessel via coolant pipe lines which extend through the shield, the coolant circulation being provided by a coolant pump which is also on the outside of the shield. To protect these components on the outside of the shield and which are of mainly or substantially cylindrical shape, semicylindrical concrete segments are interfitted around them to form complete outer cylinders which are retained against outward separation radially from the components, by rings of high tensile steel which may be interspaced so closely that they provide, in effect, an outer steel cylinder. The invention is particularly applicable to pressurized-water coolant reactor installations

Shielding container for radioactive isotopes

International Nuclear Information System (INIS)

Sumi, Tetsuo; Tosa, Masayoshi; Hatogai, Tatsuaki.

1975-01-01

Object: To effect opening and closing bidirectional radiation used particularly for a gamma densimeter or the like by one operation. Structure: This device comprises a rotatable shielding body for receiving radioactive isotope in the central portion thereof and having at least two radiation openings through which radiation is taken out of the isotope, and a shielding container having openings corresponding to the first mentioned radiation openings, respectively. The radioactive isotope is secured to a rotational shaft of the shielding body, and the shielding body is rotated to register the openings of the shielding container with the openings of the shielding body or to shield the openings, thereby effecting radiation and cut off of gamma ray in the bidirection by one operation. (Kamimura, M.)

Manual on shielded enclosures. Incorporating: Applications guide, procedures guide, basics guide

International Nuclear Information System (INIS)

1996-01-01

This publication is part of practical radiation safety manual series for different fields of application aimed primarily at persons handling radiation sources on a daily routine basis, which could at same time be used by the competent authorities, supporting their efforts in the radiation protection training of workers or medical assistance personnel or helping on-site management to set up local radiation protection rules. It is dedicated to shielding enclosures: their application and procedures guides

Gamma ray shielding properties of PbO-Li2O-B2O3 glasses

Science.gov (United States)

Kumar, Ashok

2017-07-01

The mass attenuation coefficients have been measured in (0.6-x) PbO-x Li2O-0.40 B2O3 (where 0≤ x≤0.25 mol%) glasses for photon energies of 356, 662, 1173 and 1332 keV in a narrow beam geometry with an overall scatter acceptance angle of 2.31°. The experimental results are found to be within 3% of their theoretical values. These coefficients were then used to obtain the values of mean free path, effective atomic number and electron density. The shielding properties of these glasses have also been compared among themselves in terms of their mean free path and radiation protection efficiency. The shielding properties prepared glasses have also been compared with standard concretes as well as with the standard shielding glasses. It is found that the prepared glasses are the better shielding substitute to the conventional concretes as well as other standard shielding glasses. The Pb3B4O9 has been found to be the most effective shield.

IMRT treatment of anal cancer with a scrotal shield

International Nuclear Information System (INIS)

Hood, Rodney C.; Wu, Q. Jackie; McMahon, Ryan; Czito, Brian; Willett, Christopher

2012-01-01

The risk of sterility in males undergoing radiotherapy in the pelvic region indicates the use of a shielding device, which offers protection to the testes for patients wishing to maintain fertility. The use of such devices in the realm of intensity-modulated radiotherapy (IMRT) in the pelvic region can pose many obstacles during simulation, treatment planning, and delivery of radiotherapy. This work focuses on the development and execution of an IMRT plan for the treatment of anal cancer using a scrotal shielding device on a clinical patient. An IMRT plan was developed using Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA), using a wide array of gantry angles as well as fixed jaw and fluence editing techniques. When possible, the entire target volume was encompassed by the treatment field. When the beam was incident on the scrotal shield, the jaw was fixed to avoid the device and the collimator rotation optimized to irradiate as much of the target as possible. This technique maximizes genital sparing and allows minimal irradiation of the gonads. When this fixed-jaw technique was found to compromise adequate coverage of the target, manual fluence editing techniques were used to avoid the shielding device. Special procedures for simulation, imaging, and treatment verification were also developed. In vivo dosimetry was used to verify and ensure acceptable dose to the gonads. The combination of these techniques resulted in a highly conformal plan that spares organs and risk and avoids the genitals as well as entrance of primary radiation onto the shielding device.

Enhancement of thermal neutron shielding of cement mortar by using borosilicate glass powder.

Science.gov (United States)

Jang, Bo-Kil; Lee, Jun-Cheol; Kim, Ji-Hyun; Chung, Chul-Woo

2017-05-01

Concrete has been used as a traditional biological shielding material. High hydrogen content in concrete also effectively attenuates high-energy fast neutrons. However, concrete does not have strong protection against thermal neutrons because of the lack of boron compound. In this research, boron was added in the form of borosilicate glass powder to increase the neutron shielding property of cement mortar. Borosilicate glass powder was chosen in order to have beneficial pozzolanic activity and to avoid deleterious expansion caused by an alkali-silica reaction. According to the experimental results, borosilicate glass powder with an average particle size of 13µm showed pozzolanic activity. The replacement of borosilicate glass powder with cement caused a slight increase in the 28-day compressive strength. However, the incorporation of borosilicate glass powder resulted in higher thermal neutron shielding capability. Thus, borosilicate glass powder can be used as a good mineral additive for various radiation shielding purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Concrete shielding for nuclear ship 'Mutsu'

International Nuclear Information System (INIS)

Nagase, Tetsuo; Saito, Tetsuo

1983-01-01

The repair works of the shielding for the nuclear ship ''Mutsu'' were completed in August, 1982. For the primary shielding, serpentine concrete was adopted as it contains a large quantity of water required for neutron shielding, and in the secondary shielding at the upper part of the reactor containment vessel, the original shielding was abolished, and the heavy concrete (high water content, high density concrete) which is effective for neutron and gamma-ray shielding was newly adopted. In this report, the design and construction using these shielding concrete are outlined. In September, 1974, Mutsu caused radiation leak during the test, and the cause was found to be the fast neutrons streaming through a gap between the reactor pressure vessel and the primary shielding. The repair works were carried out in the Sasebo Shipyard. The outline of the repair works of the shielding is described. The design condition for the shielding, the design standard for the radiation dose outside and inside the ship, the method of shielding analysis and the performance required for shielding concrete are reported. The selection of materials, the method of construction and mixing ratio, the evaluation of the soundness and properties of concrete, and the works of placing the shielding concrete are outlined. (Kako, I.)

Beta induced Bremsstrahlung dose rate in concrete shielding

International Nuclear Information System (INIS)

Manjunatha, H.C.

2013-01-01

Dosimetric study of beta-induced Bremsstrahlung in concrete is importance in the field of radiation protection. The efficiency, intensity and dose rate of beta induced Bremsstrahlung by 113 pure beta nuclides in concrete shielding is computed. The Bremsstrahlung dosimetric parameters such as the efficiency (yield), Intensity and dose rate of Bremsstrahlung are low for 199 Au and high for 104 Tc in concrete. The efficiency, Intensity and dose rate of Bremsstrahlung increases with maximum energy of beta nuclide (Emax) and modified atomic number (Zmod) of the target. The estimated Bremsstrahlung efficiency, Intensity and dose rate are useful in the calculations photon track-length distributions. These parameters are useful to determine the quality and quantity of the radiation (known as the source term). Precise estimation of this source term is very important in planning of radiation shielding. (author)

Determination of shielding factors for typical buildings in Brazil

International Nuclear Information System (INIS)

Salinas, Isabel Cristina Poquet

2006-10-01

This study presents a methodology for the determination of the air kerma inside buildings due to contamination on the external surfaces and the shielding factors for the construction material to be used on emergency assessment systems for urban areas. The commonly used construction materials were simulated with the MCNP computer code. A special methodology to simulate the bricks with holes were developed, mixing all different regions into a single one, making the simulation easier and faster. The effective density and the attenuation coefficients for the 50-3000 keV energy range were determined. The effective protection for the bricks with no cement cover decreases by 40-50% for energies greater then 300 keV when compared to bricks covered on both sides. With the data made available it was possible to evaluate the influence of the construction materials densities and thickness on the exposure due to external surfaces contamination and to estimate the error on the dose when the shielding factor applied on the calculation differs from the more realistic ones. The shielding factors for three types of walls were determined for a five rooms house. Special protection procedures should be applied for houses built with bricks with no cement cover, because they are due to the double of the dose when compared to houses built with bricks two-sided cement covered. The influence of windows and doors were evaluated too. This work was developed at the IRD in order to provide information on the construction material commonly uses on building in Brazil. (author)

Dynamic Analysis of AP1000 Shield Building Considering Fluid and Structure Interaction Effects

Directory of Open Access Journals (Sweden)

Qiang Xu

2016-02-01

Full Text Available The shield building of AP1000 was designed to protect the steel containment vessel of the nuclear reactor. Therefore, the safety and integrity must be ensured during the plant life in any conditions such as an earthquake. The aim of this paper is to study the effect of water in the water tank on the response of the AP1000 shield building when subjected to three-dimensional seismic ground acceleration. The smoothed particle hydrodynamics method (SPH and finite element method (FEM coupling method is used to numerically simulate the fluid and structure interaction (FSI between water in the water tank and the AP1000 shield building. Then the grid convergence of FEM and SPH for the AP1000 shield building is analyzed. Next the modal analysis of the AP1000 shield building with various water levels (WLs in the water tank is taken. Meanwhile, the pressure due to sloshing and oscillation of the water in the gravity drain water tank is studied. The influences of the height of water in the water tank on the time history of acceleration of the AP1000 shield building are discussed, as well as the distributions of amplification, acceleration, displacement, and stresses of the AP1000 shield building. Research on the relationship between the WLs in the water tank and the response spectrums of the structure are also taken. The results show that the high WL in the water tank can limit the vibration of the AP1000 shield building and can more efficiently dissipate the kinetic energy of the AP1000 shield building by fluid-structure interaction.

Shielding container

International Nuclear Information System (INIS)

Darling, K.A.M.

1981-01-01

A shielding container incorporates a dense shield, for example of depleted uranium, cast around a tubular member of curvilinear configuration for accommodating a radiation source capsule. A lining for the tubular member, in the form of a close-coiled flexible guide, provides easy replaceability to counter wear while the container is in service. Container life is extended, and maintenance costs are reduced. (author)

Attenuation characteristics of materials used in radiation protection as radiation shielding

International Nuclear Information System (INIS)

Almeida Junior, Airton T.; Araujo, F.G.S.; Nogueira, M.S.; Santos, M.A.P.

2013-01-01

Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60 Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness.Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60 Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness. (author)

30 CFR 56.15004 - Eye protection.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection. 56.15004 Section 56.15004... SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15004 Eye protection. All persons shall wear safety glasses, goggles, or face shields or other suitable...

Evidence for an extensive Phanerozoic sediment cover on the Canadian and Fenno-Scandian shields

Energy Technology Data Exchange (ETDEWEB)

Laine, E.P.; Dickson, S.M.

1985-01-01

Examination of the age and diameter of 75 terrestrial meteorite impact craters taken from platform and shield regions throughout the world suggest that both the Canadian and Fenno-Scandian Shields were covered by a sedimentary blanket during a portion of the Phanerozoic. Subsequent erosion, fostered perhaps by a combination of glacial and tectonic processes, has exposed both of these shields to reveal an anomalous distribution of craters through time. The primary evidence for sedimentary cover and subsequent erosion is in the form of a 280 Myr gap in the record of craters less than 15 km in diameter. Small craters of Cambrian, Ordovician and Silurian age are found in shield regions, suggesting either a thin or non-existent sediment cover during this period. However, there is no record of small diameter craters on either shield of Devonian, Carboniferous, Permian, Triassic, or Jurassic age (400 to 120 Myr). This 280 Myr gap suggests that the shields were protected from smaller body impacts by a sedimentary cover. In contrast, the record of impacts on platform sediments implies no such hiatus in the infall of cosmic bodies to the earth's surface between the Devonian and the Early Cretaceous. Subsequent erosion, perhaps by Early Cretaceous time, exposed the shields to further bombardment. In addition, pre-Devonian craters became exhumed. Thus, the record of impact craters suggests that the Canadian and Fenno-Scandian Shields were covered by sediments while part of Pangaea.

Conservative method for determination of material thickness used in shielding of veterinary facilities

International Nuclear Information System (INIS)

Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F.

2014-01-01

For determination of an effective method for shielding of veterinary rooms, was provided shielding methods generally used in rooms which works with X-ray production and radiotherapy. Every calculation procedure is based in traditional variables used to transmission calculation. The thickness of the materials used for primary and secondary shieldings are obtained to respect the limits set by the Brazilian National Nuclear Energy Commission (CNEN). This work presents the development of a computer code in order to serve as a practical tool for determining rapid and effective materials and their thicknesses to shield veterinary facilities. The code determines transmission values of the shieldings and compares them with data from transmission 'maps' provided by NCRP-148 report. These 'maps' were added to the algorithm through interpolation techniques of curves of materials used for shielding. Each interpolation generates about 1,000,000 points that are used to generate a new curve. The new curve is subjected to regression techniques, which makes possible to obtain nine degree polynomial, and exponential equations. These equations whose variables consist of transmission of values, enable trace all the points of this curve with high precision. The data obtained from the algorithm were satisfactory with official data presented by the National Council of Radiation Protection and Measurements (NCRP) and can contribute as a practical tool for verification of shielding of veterinary facilities that require using Radiotherapy techniques and X-ray production

Antibodies from a Human Survivor Define Sites of Vulnerability for Broad Protection Against Ebolaviruses

Science.gov (United States)

2017-03-31

search, analyzed data, and wrote and/or edited the paper . E.G. and L.M.W. designed the germline-reverted constructs and E.G., L.M.W., A.Z.W., D.M.A... albumin (PBSA), and incubated with dilutions of test antibody (5, 50 nM). Bound Abs were detected with anti-human IgG conjugated to horseradish

Use of lead shielding on pregnant patients undergoing CT scans: Results of an international survey

Energy Technology Data Exchange (ETDEWEB)

Iball, Gareth R., E-mail: gri@medphysics.leeds.ac.u [Department of Medical Physics and Engineering, Old Medical School, Leeds General Infirmary, Leeds, W. Yorkshire LS1 3EX (United Kingdom); Brettle, David S. [Department of Medical Physics and Engineering, Old Medical School, Leeds General Infirmary, Leeds, W. Yorkshire LS1 3EX (United Kingdom)

2011-05-15

Aim: An online survey has been used to assess the use of abdominal lead shielding on pregnant patients undergoing CT scans. The aim of the study was to identify potential geographical variations in the use of such shielding as well as the opinions of the users in terms of the weight, manoeuvrability and ergonomics of the lead shields. Materials and methods: The online questionnaire was distributed to CT Radiographers in the UK, Europe, North America and Australia and responses were gathered electronically over a six month period. All completed responses were downloaded and subsequently analysed for each geographical region. Results: In total, 390 completed questionnaires were received with over 100 from each of the UK, North America and Australia. The use of lead shielding was found to vary significantly across the globe with the highest usage in North America (94.5%) and the lowest usage in Europe (46.3%). Approximately 20% of all respondents said that they experienced occupationally related back pain and 25% of all respondents said that patients complained about the weight of the shielding. Conclusion: Significant geographical variations in both the use of lead shielding for foetal radiation protection and the users' opinions of the shielding devices that are used have been identified and it has become clear that existing shielding solutions are not optimised for this task.

Wood metal. A material of interest for the preparation of individual collimators and radiation protective means

International Nuclear Information System (INIS)

Schumann, E.; Keiner, P.; Klose, E.

1978-01-01

On the grounds of its physical properties Wood metal is suitable for the preparation of individual collimators, shields and other radiation protective means in clinical radiology. Advantages and disadvantages of these self-made protective means are discussed. Its use for constructing special shielding elements and filters applied in radiotherapy as well as for shielding syringes applied in nuclear medicine is demonstrated. (author)

Shielding structure analysis for LSDS facility

Energy Technology Data Exchange (ETDEWEB)

Choi, Hong Yeop; Kim, Jeong Dong; Lee, Yong Deok; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

The nuclear material (Pyro, Spent nuclear fuel) itself and the target material to generate neutrons is the LSDS system for isotopic fissile assay release of high intensity neutron and gamma rays. This research was performed to shield from various strong radiation. A shielding evaluation was carried out with a facilities model of LSDS system. The MCNPX 2.5 code was used and a shielding evaluation was performed for the shielding structure and location. The radiation dose based on the hole structure and location of the wall was evaluated. The shielding evaluation was performed to satisfy the safety standard for a normal person (1 μSv/h) and to use enough interior space. The MCNPX2.5 code was used and a dose evaluation was performed for the location of the shielding material, shielding structure, and hole structure. The evaluation result differs according to the shielding material location. The dose rate was small when the shielding material was positioned at the center. The dose evaluation result regarding the location of the shielding material was applied to the facility and the shielding thickness was determined (In 50 cm + Borax 5 cm + Out 45cm). In the existing hole structure, the radiation leak is higher than the standard. A hole structure model to prevent leakage of radiation was proposed. The general public dose limit was satisfied when using the concrete reinforcement and a zigzag structure. The shielding result will be of help to the facility shielding optimization.

Shielding structure analysis for LSDS facility

International Nuclear Information System (INIS)

Choi, Hong Yeop; Kim, Jeong Dong; Lee, Yong Deok; Kim, Ho Dong

2014-01-01

The nuclear material (Pyro, Spent nuclear fuel) itself and the target material to generate neutrons is the LSDS system for isotopic fissile assay release of high intensity neutron and gamma rays. This research was performed to shield from various strong radiation. A shielding evaluation was carried out with a facilities model of LSDS system. The MCNPX 2.5 code was used and a shielding evaluation was performed for the shielding structure and location. The radiation dose based on the hole structure and location of the wall was evaluated. The shielding evaluation was performed to satisfy the safety standard for a normal person (1 μSv/h) and to use enough interior space. The MCNPX2.5 code was used and a dose evaluation was performed for the location of the shielding material, shielding structure, and hole structure. The evaluation result differs according to the shielding material location. The dose rate was small when the shielding material was positioned at the center. The dose evaluation result regarding the location of the shielding material was applied to the facility and the shielding thickness was determined (In 50 cm + Borax 5 cm + Out 45cm). In the existing hole structure, the radiation leak is higher than the standard. A hole structure model to prevent leakage of radiation was proposed. The general public dose limit was satisfied when using the concrete reinforcement and a zigzag structure. The shielding result will be of help to the facility shielding optimization

Assessment of radiation shielding materials for protection of space crews using CR-39 plastic nuclear track detector

International Nuclear Information System (INIS)

DeWitt, J.M.; Benton, E.R.; Uchihori, Y.; Yasuda, N.; Benton, E.V.; Frank, A.L.

2009-01-01

A significant obstacle to long duration human space exploration such as the establishment of a permanent base on the surface of the Moon or a human mission to Mars is the risk posed by prolonged exposure to space radiation. In order to keep mission costs at acceptable levels while simultaneously minimizing the risk from radiation to space crew health and safety, a judicious use of optimized shielding materials will be required. We have undertaken a comprehensive study using CR-39 plastic nuclear track detector (PNTD) to characterize the radiation shielding properties of a range of materials-both common baseline materials such as Al and polyethylene, and novel multifunctional materials such as carbon composites-at heavy ion accelerators. The study consists of analyzing CR-39 PNTD exposed in front of and behind shielding targets of varying composition and at a number of depths (target thicknesses) relevant to the development and testing of materials for space radiation shielding. Most targets consist of 10 cm x 10 cm slabs of solid materials ranging in thickness from 1 to >30 g/cm 2 . Exposures have been made to beams of C, O, Ne, Si, Ar, and Fe at energies ranging from 290 MeV/amu to 1 GeV/amu at the National Institute of Radiological Sciences HIMAC and the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory. Analysis of the exposed detectors yields LET spectrum, dose, and dose equivalent as functions of target depth and composition, and incident heavy ion charge, energy, and fluence. Efforts are currently underway to properly weigh and combine these results into a single quantitative estimate of a material's ability to shield space crews from the interplanetary galactic cosmic ray flux.

Investigation of P(VDF-TrFE)/ZrO{sub 2}-MMA polymer composites applied to radiation shielding

Energy Technology Data Exchange (ETDEWEB)

Fontainha, C.C.P. [Depto. de Engenharia Nuclear - UFMG, Av. Antonio Carlos 6627, 31270-970 Belo Horizonte, MG (Brazil); Baptista Neto, A.T.; Santos, A.P.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear, Av. Antonio Carlos 6627, C.P. 941, 30270-901, Belo Horizonte, MG (Brazil)

2015-07-01

Exposure to high radiation dose in medical diagnostic imaging procedures can lead patients to suffer tissue damaging. However, there are several studies that identify significant dose reduction with the use of radiation protective attenuators, minimizing the delivered dose in the region that covers the main beam, while preserving the diagnostic quality of the generated image. Most radiation attenuator materials are produced from shielding metal containing composites, whose efficiency is the goal of investigations around the world. In this context, polymeric materials were chosen for this investigation in order to provide light-weighted and flexible protective composites, a must in personal protective shielding. Therefore, this work is concerned to the investigation of poly(vinylidene fluoride - try-fluor-ethylene) [P(VDF-TrFE)] copolymers mixed with zirconia nanoparticles. The resulting polymer composites, prepared with 1, 2, 3, 5 and 10 at.% of ZrO{sub 2} nanoparticles, were investigated for application as protective shielding in some interventional radiology procedures. Two variety of composites were produced, one using pure ZrO{sub 2} nanoparticles and the other using sol-gel route with zirconium butoxide as the precursor for zirconium oxide nano-clusters. The P(VDFTrFE)/ ZrO2-MMA polymer composites produced by sol-gel route have provided a much better dispersion of the pure ZrO{sub 2} material into the P(VDF-TrFE) host matrix. UV-Vis and FTIR spectrometry and differential scanning calorimetry (DSC) were used to characterize the composite samples. FTIR data reveal a possible link between the MMA monomers with the P(VDF-TrFE) chain through shared C=O bonds. The radiation shielding characterization was conducted by using a 70 kV x-rays beam which is applicable, for instances, in catheter angiography. The results demonstrate that composites with 10% of ZrO{sub 2}, and only 1.0 mm thick, can attenuate 60% of the x-rays beam. The composite density was evaluated to be

Sci-Fri AM: Quality, Safety, and Professional Issues 03: The Increasing Costs of Shielding Diagnostic CT Scanners in Ontario

Energy Technology Data Exchange (ETDEWEB)

Richer, Jeff; Frimeth, Jeff; Nesbitt, James [Windsor Regional Hospital, Xspect Inc., XRCT Inc. (Canada)

2016-08-15

Purpose: In Ontario, shielding for all X-ray machines, including CT scanners, must be evaluated according to Safety Code 20A (Health Canada, 1983) which is based on NCRP-49 (NCRP, 1976). NCRP-147 (NCRP, 2004) is the international standard for shielding calculations of CT scanners and is also referenced in Safety Code 35 (Health Canada, 2008) which, was published to supersede SC20A. The goal of this work is to demonstrate the cost effectiveness of NCRP-147 for CT scanner shielding. Methods: CT scanner shielding calculations are performed using SC20A and NCRP-147: A room located on the third floor with the nearest building 75m away A room with high occupancy uncontrolled adjacent spaces Two side by side rooms on the main floor Results: 1. SC20A: The exterior windows required 0.1mm of Pb to protect the public who may occupy the building at 75m. 1. NCRP-147: No additional shielding required. 2. SC20A: Two walls adjacent to high occupancy uncontrolled space required an additional 1.58mm Pb. 2. NCRP-147: No additional shielding required. 3. SC20A: The entire floor and ceiling slabs in both rooms required an additional 0.79mm Pb. In addition, 0.79mm Pb was added to the walls from the ceiling to overlap the existing Pb shielding in the walls. 3. NCRP-147: No additional shielding required. Conclusion: The application of NCRP Report No. 147 affords the required protection to staff and the public, in the true spirit of the ALARA principle, taking into account relevant social and economic factors.

Re-evaluation of the shielding adequacy of the brachytherapy treatment room at Korle-Bu teaching hospital, Ghana

International Nuclear Information System (INIS)

Arwui, C. C.

2009-06-01

Staff and the general public's safety during the operation of the 137 Cs brachytherapy unit at the Korle Bu teaching hospital depends on the adequacy of the shielding of the facility. Shielding design of the brachytherapy unit at the hospital was based on postulated workload and postulated occupancy factors to critical locations at the facility where the public and staff may occupy. This facility has been in existence for the past twelve (12) years and has accumulated operational workload data which differs from the postulated one. A study was carried out to re-evaluate the integrity of the biological shielding of the 137 Cs brachytherapy unit. This study analyzed the accumulated workload data and used the information to perform shielding calculations to verify the adequacy of the biological shielding thicknesses to provide sufficient protection of staff and the public. Dose rate calculations were verified by measurements with calibrated dose rate meters. This provided the basis for determining the current state of protection and safety for staff and the general public. The results show that despite the variation in actual and postulated workloads, the dose rates were below the reference values of 0.5μSv/h for public areas and 7.5μSv/h for controlled areas. It was confirmed that the present shielding thickness of 535 mm can accommodate a high dose rate (HDR) 192 Ir source with activity in the range 370 - 570 GBq with an operational workload of 30 patients per week and an average treatment time of 10 minutes.

IMRT treatment of anal cancer with a scrotal shield.

Science.gov (United States)

Hood, Rodney C; Wu, Q Jackie; McMahon, Ryan; Czito, Brian; Willett, Christopher

2012-01-01

The risk of sterility in males undergoing radiotherapy in the pelvic region indicates the use of a shielding device, which offers protection to the testes for patients wishing to maintain fertility. The use of such devices in the realm of intensity-modulated radiotherapy (IMRT) in the pelvic region can pose many obstacles during simulation, treatment planning, and delivery of radiotherapy. This work focuses on the development and execution of an IMRT plan for the treatment of anal cancer using a scrotal shielding device on a clinical patient. An IMRT plan was developed using Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA), using a wide array of gantry angles as well as fixed jaw and fluence editing techniques. When possible, the entire target volume was encompassed by the treatment field. When the beam was incident on the scrotal shield, the jaw was fixed to avoid the device and the collimator rotation optimized to irradiate as much of the target as possible. This technique maximizes genital sparing and allows minimal irradiation of the gonads. When this fixed-jaw technique was found to compromise adequate coverage of the target, manual fluence editing techniques were used to avoid the shielding device. Special procedures for simulation, imaging, and treatment verification were also developed. In vivo dosimetry was used to verify and ensure acceptable dose to the gonads. The combination of these techniques resulted in a highly conformal plan that spares organs and risk and avoids the genitals as well as entrance of primary radiation onto the shielding device. Copyright © 2012 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Effectiveness of Bismuth Shield to Reduce Eye Lens Radiation Dose Using the Photoluminescence Dosimetry in Computed Tomography

International Nuclear Information System (INIS)

Jung, Mi Young; Kweon, Dae Cheol; Kwon, Soo Il

2009-01-01

The purpose of our study was to determine the eye radiation dose when performing routine multi-detector computed tomography (MDCT). We also evaluated dose reduction and the effect on image quality of using a bismuth eye shield when performing head MDCT. Examinations were performed with a 64MDCT scanner. To compare the shielded/unshielded lens dose, the examination was performed with and without bismuth shielding in anthropomorphic phantom. To determine the average lens radiation dose, we imaged an anthropomorphic phantom into which calibrated photoluminescence glass dosimeter (PLD) were placed to measure the dose to lens. The phantom was imaged using the same protocol. Radiation doses to the lens with and without the lens shielding were measured and compared using the Student t test. In the qualitative evaluation of the MDCT scans, all were considered to be of diagnostic quality. We did not see any differences in quality between the shielded and unshielded brain. The mean radiation doses to the eye with the shield and to those without the shield were 21.54 versus 10.46 mGy, respectively. The lens shield enabled a 51.3% decrease in radiation dose to the lens. Bismuth in-plane shielding for routine eye and head MDCT decreased radiation dose to the lens without qualitative changes in image quality. The other radiosensitive superficial organs specifically must be protected with shielding.

Radiation shielding calculation using MCNP

International Nuclear Information System (INIS)

Masukawa, Fumihiro

2001-01-01

To verify the Monte Carlo code MCNP4A as a tool to generate the reference data in the shielding designs and the safety evaluations, various shielding benchmark experiments were analyzed using this code. These experiments were categorized in three types of the shielding subjects; bulk shielding, streaming, and skyshine. For the variance reduction technique, which is indispensable to get meaningful results with the Monte Carlo shielding calculation, we mainly used the weight window, the energy dependent Russian roulette and spitting. As a whole, our analyses performed enough small statistical errors and showed good agreements with these experiments. (author)

MMW [multimegawatt] shielding design and analysis

International Nuclear Information System (INIS)

Olson, A.P.

1988-01-01

Reactor shielding for multimegawatt (MMW) space power must satisfy a mass constraint as well as performance specifications for neutron fluence and gamma dose. A minimum mass shield is helpful in attaining the launch mass goal for the entire vehicle, because the shield comprises about 1% to 2% of the total vehicle mass. In addition, the shield internal heating must produce tolerable temperatures. The analysis of shield performance for neutrons and gamma rays is emphasized. Topics addressed include cross section preparation for multigroup 2D S/sub n/-transport analyses, and the results of parametric design studies on shadow shield performance and mass versus key shield design variables such as cone angle, number, placement, and thickness of layers of tungsten, and shield top radius. Finally, adjoint methods are applied to the shield in order to spatially map its relative contribution to dose reduction, and to provide insight into further design optimization. 7 refs., 2 figs., 3 tabs

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters

Science.gov (United States)

Shavers, M. R.; Zapp, N.; Barber, R. E.; Wilson, J. W.; Qualls, G.; Toupes, L.; Ramsey, S.; Vinci, V.; Smith, G.; Cucinotta, F. A.

2004-01-01

With 5-7 month long duration missions at 51.6° inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (C nH n) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry.

LOFT shield tank steady state temperatures with addition of gamma and neutron shielding

International Nuclear Information System (INIS)

Kyllingstad, G.

1977-01-01

The effect of introducing a neutron and gamma shield into the annulus between the reactor vessel and the shield tank is analyzed. This addition has been proposed in order to intercept neutron streaming up the annulus during nuclear operations. Its installation will require removal of approximately 20- 1 / 2 inches of stainless steel foil insulation at the top of the annulus. The resulting conduction path is believed to result in increased water temperatures within the shield tank, possibly beyond the 150 0 F limit, and/or cooling of the reactor vessel nozzles such that adverse thermal stresses would be generated. A two dimensional thermal analysis using the finite element code COUPLE/MOD2 was done for the shield tank system illustrated in the figure (1). The reactor was assumed to be at full power, 55 MW (th), with a loop flow rate of 2.15 x 10 6 lbm/hr (268.4 kg/s) at 2250 psi (15.51 MPa). Calculations indicate a steady state shield tank water temperature of 140 0 F (60 0 C). This is below the 150 0 F (65.56 0 C) limit. Also, no significant changes in thermal gradients within the nozzle or reactor vessel wall are generated. A spacer between the gamma shield and the shield tank is recommended, however, in order to ensure free air circulation through the annulus

[Optimizing staff radiation protection in radiology by minimizing the effective dose].

Science.gov (United States)

von Boetticher, H; Lachmund, J; Hoffmann, W; Luska, G

2006-03-01

In the present study the optimization of radiation protection devices is achieved by minimizing the effective dose of the staff members since the stochastic radiation effects correlate to the effective dose. Radiation exposure dosimetry was performed with TLD measurements using one Alderson Phantom in the patient position and a second phantom in the typical position of the personnel. Various types of protective clothing as well as fixed shields were considered in the calculations. It was shown that the doses of the unshielded organs (thyroid, parts of the active bone marrow) contribute significantly to the effective dose of the staff. Therefore, there is no linear relationship between the shielding factors for protective garments and the effective dose. An additional thyroid protection collar reduces the effective dose by a factor of 1.7 - 3.0. X-ray protective clothing with a 0.35 mm lead equivalent and an additional thyroid protection collar provides better protection against radiation than an apron with a 0.5 mm lead equivalent but no collar. The use of thyroid protection collars is an effective preventive measure against exceeding occupational organ dose limits, and a thyroid shield also considerably reduces the effective dose. Therefore, thyroid protection collars should be a required component of anti-X protection.

Concrete shielding for nuclear ship 'Mutsu'

International Nuclear Information System (INIS)

Nagase, Tetsuo; Nakajima, Tadao; Okumura, Tadahiko; Saito, Tetsuo

1983-01-01

The nuclear ship ''Mutsu'' was constructed in 1970 as the fourth in the world. On September 1, 1974, during the power raising test in the Pacific Ocean, radiation leak was detected. As the result of investigation, it was found that the cause was the fast neutrons streaming through the gap between the reactor pressure vessel and the primary shield. In order to repair the shielding facility, the Japan Nuclear Ship Research Development Agency carried out research and development and shielding design. It was decided to adopt serpentine concrete for the primary shield, which is the excellent moderator of fast neutrons even at high temperature, and heavy concrete for the secondary shield, which is effective for shielding both gamma ray and neutron beam. The repair of shielding was carried out in the Sasebo Shipyard, and completed in August, 1982. The outline of the repair work is reported. The weight increase was about 300 t. The conditions of the shielding design, the method of shielding analysis, the performance required for the shielding concrete, the preliminary experiment on heavy concrete and the construction works of serpentine concrete and heavy concrete are described. (Kako, I.)

Accelerator shielding benchmark problems

International Nuclear Information System (INIS)

Hirayama, H.; Ban, S.; Nakamura, T.

1993-01-01

Accelerator shielding benchmark problems prepared by Working Group of Accelerator Shielding in the Research Committee on Radiation Behavior in the Atomic Energy Society of Japan were compiled by Radiation Safety Control Center of National Laboratory for High Energy Physics. Twenty-five accelerator shielding benchmark problems are presented for evaluating the calculational algorithm, the accuracy of computer codes and the nuclear data used in codes. (author)

Dosimetric evaluation of indigenously developed non-lead bilayered radiation protective aprons

International Nuclear Information System (INIS)

Senthilkumar, S.

2018-01-01

Radiation shielding garments are commonly used to protect medical patients and radiation workers from X-radiation exposure during diagnostic imaging in hospitals. Originally, protective aprons consisted of lead-impregnated vinyl with a shielding equivalent given in millimeters of lead. All contained up to 2 mm of lead. While lead has long been used to shield patients from X-rays, its toxicity poses a health threat if the protective apron containing the metal wear out or the lead gets damaged. However, lead garments must be treated as hazardous waste for disposal and are heavy, causing back strain and other orthopedic problems for those who must wear them for long periods of time. The main purpose of this work was to indigenously develop light weight non lead based bilayered radiation protective aprons and evaluate dosimetrically with different combination of fabricated non lead materials and commercially available lead based aprons

External dosimetry sources and shielding

International Nuclear Information System (INIS)

Calisto, Washington

1994-01-01

A definition of external dosimetry r external sources dosimetry,physical and mathematical treatment of the interaction of gamma radiation with a minimal area in that direction. Concept of attenuation coefficient, cumulated effect by polyenergetic sources, exposition rate, units, cumulated dose,shielding, foton shielding, depth calculation, materials used for shielding.Beta shielding, consideration of range and maximum β energy , low stopping radiation by use of low Z shielding. Tables for β energy of β emitters, I (tau) factor, energy-range curves for β emitters in aqueous media, gamma attenuation factors for U, W and Pb. Y factor for bone tissue,muscle and air, build-up factors

Radiation Protection in PET-CT

International Nuclear Information System (INIS)

2011-10-01

The presentation is based on the following areas: radiological monitoring installations in the production of PET radiopharmaceuticals, personal dose, dosage advertising, nuclear medicine, PET, radiation protection of patients, requirements for medical practice, regulatory aspects, dose calculation, shields, quantities, center Cudim, cyclotron and synthesis of radiopharmaceuticals, biological effects of radiation protection practices.

Method for dismantling shields

International Nuclear Information System (INIS)

Fukuzawa, Rokuro; Kondo, Nobuhiro; Kamiyama, Yoshinori; Kawasato, Ken; Hiraga, Tomoaki.

1990-01-01

The object of the present invention is to enable operators to dismantle shieldings contaminated by radioactivity easily and in a short period of time without danger of radiation exposure. A plurality of introduction pipes are embedded previously to the shielding walls of shielding members which contain a reactor core in a state where both ends of the introduction pipes are in communication with the outside. A wire saw is inserted into the introduction pipes to cut the shieldings upon dismantling. Then, shieldings can be dismantled easily in a short period of time with no radiation exposure to operator's. Further, according to the present invention, since the wire saw can be set easily and a large area can be cut at once, operation efficiency is improved. Further, since remote control is possible, cutting can be conducted in water and complicated places of the reactor. Biting upon starting the wire saw in the introduction pipe is reduced to facilitate startup for the rotation. (I.S.)

Magnetic shield effect simulation of superconducting film shield covering directly coupled HTS dc-SQUID magnetometer

International Nuclear Information System (INIS)

Terauchi, N.; Noguchi, S.; Igarashi, H.

2011-01-01

A superconducting film shield over a SQUID ring improves the robustness of the SQUID with respect to magnetic noise. Supercurrent in the SQUID magnetometer and the superconducting film shield were simulated. The superconducting film shield reduces the influence of the external magnetic field on the SQUID ring. An HTS SQUID is a high sensitive magnetic sensor. In recent years, the HTS SQUID is widely used in various applications. In some applications, high robustness with respect to magnetic noise is required to realize stable operation at outside of a magnetic shielding room. The target of this paper is a directly coupled HTS dc-SQUID magnetometer. To enhance the robustness of the SQUID magnetometer, use of a superconducting thin film shield has been proposed. The magnetic field directly penetrating the SQUID ring causes the change of the critical current of Josephson junction, and then the SQUID magnetometer transitions into inoperative state. In order to confirm the magnetic shield effect of the superconducting film shield, electromagnetic field simulation with 3D edge finite element method was performed. To simulate the high temperature superconductor, E-J characteristics and c-axis anisotropy are considered. To evaluate the effect of the superconducting film shield, an external magnetic field which is supposed to be a magnetic noise is applied. From the simulation results, the time transition of the magnetic flux penetrating the SQUID ring is investigated and the effect of the superconducting film shield is confirmed. The amplitude of the magnetic flux penetrating the SQUID ring can be reduced to about one-sixth since the superconducting film shield prevents the magnetic noise from directly penetrating the SQUID ring.

Passive magnetic shielding in MRI-Linac systems

Science.gov (United States)

Whelan, Brendan; Kolling, Stefan; Oborn, Brad M.; Keall, Paul

2018-04-01

Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

MATHEMATICAL MODELLING OF THE SHIELDING EFFECTIVENESS FOR PES/STAINLESS STEEL FABRICS

Directory of Open Access Journals (Sweden)

RADULESCU Ion Razvan

2017-05-01

Full Text Available Textile screens for electromagnetic radiation represent a modern solution, due to their flexibility, lightweight and good mechanical resistance. Electromagnetic shielding is a must in various applications, while strict regulations are set for electromagnetic compatibility. Conductive fabrics are widely used for electronic equipment covers, RF suits or EMI protection tents. This paper aims to investigate the shielding effectiveness of conductive woven fabrics with stainless steel yarns at different weft distances [2,3,4,5 mm]. These conductive fabrics were investigated for their physical-mechanical properties (mass per surface unit, density on warp and weft direction and thickness, within the INCDTP accredited laboratories. The conductive fabrics as well as combinations thereof where tested for their shielding effectiveness accordingly to the standard ASTM ES 07, within the EMC laboratories of ICPE-CA. A signal generator, an amplifier, a TEM Cell and a spectrum analyser were used were used for this purpose. Graphs in logarithmic scale were issued for the shielding effectiveness analysis. Moreover, an experimental factorial plan was conceived for obtaining a mathematical model for the studied fabrics in relation to the weft distance between the conductive yarns. The coefficients of the mathematical model were obtained through the least squares regression method in Excel, while the response curve was designed in Matlab. The response curve enables the computation of intermediate values of the shielding effectiveness in relation to the distance between conductive yarns.

Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses [Shielding Synchrotron Light Sources: Importance of geometry for calculating radiation levels from beam losses

International Nuclear Information System (INIS)

Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

2016-01-01

Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. Lastly, the principles used to provide

Investigation of ionizing radiation shielding effectiveness of decorative building materials used in Bangladeshi dwellings

International Nuclear Information System (INIS)

Yesmin, Sabina; Sonker Barua, Bijoy; Uddin Khandaker, Mayeen; Tareque Chowdhury, Mohammed; Kamal, Masud; Rashid, M.A.; Miah, M.M.H.; Bradley, D.A.

2017-01-01

Following the rapid growing per capita income, a major portion of Bangladeshi dwellers is upgrading their non-brick houses by rod-cement-concrete materials and simultaneously curious to decorate the houses using luxurious marble stones. Present study was undertaken to investigate the gamma-ray attenuation co-efficient of decorative marble materials leading to their suitability as shielding of ionizing radiation. A number of commercial grades decorative marble stones were collected from home and abroad following their large-scale uses. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the mass attenuation coefficients of the studied materials for high energy photons. Some allied parameters such as half-value layer and radiation protection efficacy of the investigated marbles were calculated. The results showed that among the studied samples, the marble ‘Carrara’ imported from Italy is suitable to be used as radiation shielding material. - Highlights: • Studies of decorative building materials for shielding of ionizing radiation. • High energy photon beam were used to obtain various interaction properties. • Marble stone ‘Carrara’ from Italy shows suitability to be used as shielding material.

Gamma ray shielding properties of PbO-Li2O-B2O3 glasses

International Nuclear Information System (INIS)

Kumar, Ashok

2017-01-01

The mass attenuation coefficients have been measured in (0.6-x) PbO-x Li 2 O-0.40 B 2 O 3 (where 0≤ x≤0.25 mol%) glasses for photon energies of 356, 662, 1173 and 1332 keV in a narrow beam geometry with an overall scatter acceptance angle of 2.31°. The experimental results are found to be within 3% of their theoretical values. These coefficients were then used to obtain the values of mean free path, effective atomic number and electron density. The shielding properties of these glasses have also been compared among themselves in terms of their mean free path and radiation protection efficiency. The shielding properties prepared glasses have also been compared with standard concretes as well as with the standard shielding glasses. It is found that the prepared glasses are the better shielding substitute to the conventional concretes as well as other standard shielding glasses. The Pb 3 B 4 O 9 has been found to be the most effective shield. - Highlights: • Shielding efficiencies of PbO-B 2 O 3 -Li 2 O glasses have been compared. • Measurements have been done for 356, 662, 1173 and 1332 keV photon energies. • Experimental values have been found to be within 3% of their theoretical ones. • Pb 3 B 4 O 9 has been found to be the most effective shield.

Scintillation counter, segmented shield

International Nuclear Information System (INIS)

Olson, R.E.; Thumim, A.D.

1975-01-01

A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

Reassessment of shielding calculations for a room housing a Cesium-137 irradiator

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Leticia S.; Barbosa, Rugles C., E-mail: leticia.fmufg@gmail.com, E-mail: rbarbosa@cnen.gov.br [Centro Regional de Ciências Nucleares do Centro Oeste (CRCN-CO/CNEN-GO), Abadia de Goiás, GO (Brazil); Rezende, Ana C.B., E-mail: anacbrz@gmail.com [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil). Escola de Engenharia

2017-07-01

This aim of this work is to reassess the shielding calculations for a room that houses an irradiator with cesium-137 ({sup 137}Cs) source with activity of 444GBq (12Ci). Shielding or barriers have the function of reducing the intensity of the radiation emitted by a radioactive source, are constituted by materials of high atomic number and guarantee the radiological protection in areas occupied by occupationally exposed individuals or by individuals of the public. The barriers located in the direction of the direct beam of radiation are called primary barriers and are thicker. Already the barriers that attenuate the radiation scattered by the radiated surface are called secondary barriers. In the new calculations, the thickness of the primary barrier was determined by model of the point nucleus model and for the secondary barriers, the differential albedo dose model was used. The results obtained show that all secondary barriers were constructed with overestimated thicknesses and that the radiological protection of individuals from the public and occupationally exposed individuals in the areas outside these barriers is guaranteed. The primary barrier was constructed with a thickness 8% smaller than the thickness obtained in the new calculations. In addition to shielding calculations, classification and signaling of adjacent areas were performed, including necessary emergency procedures. The necessary instrumentation for monitoring these areas was also determined. (author)

Reassessment of shielding calculations for a room housing a Cesium-137 irradiator

International Nuclear Information System (INIS)

Oliveira, Leticia S.; Barbosa, Rugles C.; Rezende, Ana C.B.

2017-01-01

This aim of this work is to reassess the shielding calculations for a room that houses an irradiator with cesium-137 ( 137 Cs) source with activity of 444GBq (12Ci). Shielding or barriers have the function of reducing the intensity of the radiation emitted by a radioactive source, are constituted by materials of high atomic number and guarantee the radiological protection in areas occupied by occupationally exposed individuals or by individuals of the public. The barriers located in the direction of the direct beam of radiation are called primary barriers and are thicker. Already the barriers that attenuate the radiation scattered by the radiated surface are called secondary barriers. In the new calculations, the thickness of the primary barrier was determined by model of the point nucleus model and for the secondary barriers, the differential albedo dose model was used. The results obtained show that all secondary barriers were constructed with overestimated thicknesses and that the radiological protection of individuals from the public and occupationally exposed individuals in the areas outside these barriers is guaranteed. The primary barrier was constructed with a thickness 8% smaller than the thickness obtained in the new calculations. In addition to shielding calculations, classification and signaling of adjacent areas were performed, including necessary emergency procedures. The necessary instrumentation for monitoring these areas was also determined. (author)

Meeting the Grand Challenge of Protecting Astronauts Health: Electrostatic Active Space Radiation Shielding for Deep Space Missions

Science.gov (United States)

Tripathi, Ram K.

2016-01-01

This report describes the research completed during 2011 for the NASA Innovative Advanced Concepts (NIAC) project. The research is motivated by the desire to safely send humans in deep space missions and to keep radiation exposures within permitted limits. To this end current material shielding, developed for low earth orbit missions, is not a viable option due to payload and cost penalties. The active radiation shielding is the path forward for such missions. To achieve active space radiation shielding innovative large lightweight gossamer space structures are used. The goal is to deflect enough positive ions without attracting negatively charged plasma and to investigate if a charged Gossamer structure can perform charge deflections without significant structural instabilities occurring. In this study different innovative configurations are explored to design an optimum active shielding. In addition, to establish technological feasibility experiments are performed with up to 10kV of membrane charging, and an electron flux source with up to 5keV of energy and 5mA of current. While these charge flux energy levels are much less than those encountered in space, the fundamental coupled interaction of charged Gossamer structures with the ambient charge flux can be experimentally investigated. Of interest are, will the EIMS remain inflated during the charge deflections, and are there visible charge flux interactions. Aluminum coated Mylar membrane prototype structures are created to test their inflation capability using electrostatic charging. To simulate the charge flux, a 5keV electron emitter is utilized. The remaining charge flux at the end of the test chamber is measured with a Faraday cup mounted on a movable boom. A range of experiments with this electron emitter and detector were performed within a 30x60cm vacuum chamber with vacuum environment capability of 10-7 Torr. Experiments are performed with the charge flux aimed at the electrostatically inflated

EBT-P gamma-ray-shielding analysis

International Nuclear Information System (INIS)

Gohar, Y.

1983-01-01

First, a one-dimensional scoping study was performed for the gamma-ray shield of the ELMO Bumpy Torus proof-of-principle device to define appropriate shielding material and determine the required shielding thickness. The dose-equivalent results are analyzed as a function of the radiation-shield thickness for different shielding options. A sensitivity analysis for the pessimistic case is given. The recommended shielding option based on the performance and cost is discussed. Next, a three-dimensional scoping study for the coil shield was performed for four different shielding options to define the heat load for each component and check the compliance with the design criterion of 10 watts maximum heat load per coil from the gamma-ray sources. Also, a detailed biological-dose survey was performed which included: (a) the dose equivalent inside and outside the building, (b) the dose equivalent from the two mazes of the building, and (c) the skyshine contribution to the dose equivalent

Permeation of Telone EC through protective gloves.

Science.gov (United States)

Zainal, Hanaa; Que Hee, Shane S

2005-09-30

Telone is a potent fumigant that is based on the chlorinated unsaturated hydrocarbon, 1,3-dichloropropene (1,3-DCP). It is often applied without dilution and so poses severe inhalation and air pollution threats. Urinary metabolites of 1,3-DCP have been detected after Telone skin exposure, so that preventing dermal exposure is also important. The objective of the study was to assess if nitrile and multi-layer ("laminated") gloves provide adequate protection against Telone EC formulation. To accomplish this, disposable (Safeskin) and chemically resistant (Sol-Vex) nitrile and laminated (Barrier mark and Silver Shield) glove materials were challenged by Telone EC with hexane liquid collection in an ASTM-type I-PTC-600 permeation cell. Analyses of cis- and trans-1,3-DCP in the collection fluid at specified times were performed on a moderately polar capillary column by gas chromatography-electron capture detection. Telone EC caused microholes in both nitrile materials, though the chemically protective material was degraded slower than the disposable nitrile. The laminated gloves offered limited protection. Silver Shield protected best because 1.5-2.3 mg 1,3-DCP permeated by 8 h relative to 2.5-7.6 mg for Barrier, implying about 2.5 times more protection for 8 h. Even for Silver Shield, the extent of protection was inadequate as illustrated by a risk assessment of the skin exposure situation. The normalized breakthrough times for both types of laminated gloves varied between 27 and 60 min. It is recommended that Viton gloves still be worn for protection.

Seminoma of the testis: is scrotal shielding necessary when radiotherapy is limited to the para-aortic nodes?

Science.gov (United States)

Bieri, S; Rouzaud, M; Miralbell, R

1999-03-01

To evaluate the influence of different shielding conditions and field geometry on the scatter dose to the remaining testicle during postoperative radiotherapy (RT) in seminoma. Testicular dose measurements were made with LiF thermoluminescent dosimeters (TLD) in 29 patients with stage I and IIA seminoma. The target volume consisted of para-aortic (PA) and para-aortic and homolateral iliac (PAI) lymph nodes in 14 and 15 patients, respectively. All patients had a scrotal shield as well as an additional block extending 7 cm inferiorly from the caudal field edge to shield the testicle from external scatter and collimator leakage. Doses with and without testicular blocks were measured for all patients. In seven patients treated exclusively to the PA region the gonadal dose was assessed according to four different shielding conditions: without any protection, with a gonadal shield alone, with the addition of an inferior field border block to the gonadal shield, and with the field border block alone. For patients treated with PAI fields the mean testicular doses per fraction were 3.89 cGy (S.D. +/- 1.44) and 1.48 cGy (S.D. +/- 0.51) without and with gonadal shielding, respectively (P-value shielding conditions, the additional external block to the testicular shield did not reduce significantly the measured dose on the testis. These results suggest a benefit of gonadal shielding even in seminoma patients undergoing radiotherapy limited to the para-aortic region.

Radiation shielding for fusion reactors

International Nuclear Information System (INIS)

Santoro, R.T.

2000-01-01

Radiation shielding requirements for fusion reactors present different problems than those for fission reactors and accelerators. Fusion devices, particularly tokamak reactors, are complicated by geometry constraints that complicate disposition of fully effective shielding. This paper reviews some of these shielding issues and suggested solutions for optimizing the machine and biological shielding. Radiation transport calculations are essential for predicting and confirming the nuclear performance of the reactor and, as such, must be an essential part of the reactor design process. Development and optimization of reactor components from the first wall and primary shielding to the penetrations and containment shielding must be carried out in a sensible progression. Initial results from one-dimensional transport calculations are used for scoping studies and are followed by detailed two- and three-dimensional analyses to effectively characterize the overall radiation environment. These detail model calculations are essential for accounting for the radiation leakage through ports and other penetrations in the bulk shield. Careful analysis of component activation and radiation damage is cardinal for defining remote handling requirements, in-situ replacement of components, and personnel access at specific locations inside the reactor containment vessel. (author)

Radiation shielding estimates for manned Mars space flight

International Nuclear Information System (INIS)

Dudkin, V.E.; Kovalev, E.E.; Kolomensky, A.V.; Sakovich, V.A.; Semenov, V.F.; Demin, V.P.; Benton, E.V.

1992-01-01

In the analysis of the required radiation shielding for spacecraft during a Mars flight, the specific effects of solar activity (SA) on the intensity of galactic and solar cosmic rays were taken into consideration. Three spaceflight periods were considered: (1) maximum SA; (2) minimum SA; and (3) intermediate SA, when intensities of both galactic and solar cosmic rays are moderately high. Scenarios of spaceflights utilizing liquid-propellant rocket engines, low-and intermediate-thrust nuclear electrojet engines, and nuclear rocket engines, all of which have been designed in the Soviet Union, are reviewed. Calculations were performed on the basis of a set of standards for radiation protection approved by the U.S.S.R. State Committee for Standards. It was found that the lowest estimated mass of a Mars spacecraft, including the radiation shielding mass, obtained using a combination of a liquid propellant engine with low and intermediate thrust nuclear electrojet engines, would be 500-550 metric tons. (author)

Shielding analysis in the design phase of the new Emergency Operation Facility for Tihange Nuclear Power Plant

Science.gov (United States)

Genard, Gilles; Portal, Romain; Bouchat, Virginie; Vanderperre, Serge

2017-09-01

In the framework of the design studies for a new Emergency Operation Facility (EOF) for Tihange NPP, radiation protection analyses are needed to comply with effective dose rate criteria. In this aim, the shielding performed by, at the one hand, external walls and roof of the building and, on the other hand, internal walls, has been sized by means of MicroShield calculations. This paper explains how the calculations for external walls, doors, roof, floor and internal walls are made. The assumptions on the source terms and on the source geometry as well as the way the shielding is determined and the results of the sizing are presented.

Shielding analysis in the design phase of the new Emergency Operation Facility for Tihange Nuclear Power Plant

Directory of Open Access Journals (Sweden)

Genard Gilles

2017-01-01

Full Text Available In the framework of the design studies for a new Emergency Operation Facility (EOF for Tihange NPP, radiation protection analyses are needed to comply with effective dose rate criteria. In this aim, the shielding performed by, at the one hand, external walls and roof of the building and, on the other hand, internal walls, has been sized by means of MicroShield calculations. This paper explains how the calculations for external walls, doors, roof, floor and internal walls are made. The assumptions on the source terms and on the source geometry as well as the way the shielding is determined and the results of the sizing are presented.

Parameters calculation of shielding experiment

International Nuclear Information System (INIS)

Gavazza, S.

1986-02-01

The radiation transport methodology comparing the calculated reactions and dose rates for neutrons and gama-rays, with experimental measurements obtained on iron shield, irradiated in the YAYOI reactor is evaluated. The ENDF/B-IV and VITAMIN-C libraries and the AMPX-II modular system, for cross sections generation collapsed by the ANISN code were used. The transport calculations were made using the DOT 3.5 code, adjusting the boundary iron shield source spectrum to the reactions and dose rates, measured at the beginning of shield. The neutron and gamma ray distributions calculated on the iron shield presented reasonable agreement with experimental measurements. An experimental arrangement using the IEA-R1 reactor to determine a shielding benchmark is proposed. (Author) [pt

Morphometry of terrestrial shield volcanoes

Science.gov (United States)

Grosse, Pablo; Kervyn, Matthieu

2018-03-01

Shield volcanoes are described as low-angle edifices built primarily by the accumulation of successive lava flows. This generic view of shield volcano morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galápagos). Here, the morphometry of 158 monogenetic and polygenetic shield volcanoes is analyzed quantitatively from 90-meter resolution SRTM DEMs using the MORVOLC algorithm. An additional set of 24 lava-dominated 'shield-like' volcanoes, considered so far as stratovolcanoes, are documented for comparison. Results show that there is a large variation in shield size (volumes from 0.1 to > 1000 km3), profile shape (height/basal width (H/WB) ratios mostly from 0.01 to 0.1), flank slope gradients (average slopes mostly from 1° to 15°), elongation and summit truncation. Although there is no clear-cut morphometric difference between shield volcanoes and stratovolcanoes, an approximate threshold can be drawn at 12° average slope and 0.10 H/WB ratio. Principal component analysis of the obtained database enables to identify four key morphometric descriptors: size, steepness, plan shape and truncation. Hierarchical cluster analysis of these descriptors results in 12 end-member shield types, with intermediate cases defining a continuum of morphologies. The shield types can be linked in terms of growth stages and shape evolution, related to (1) magma composition and rheology, effusion rate and lava/pyroclast ratio, which will condition edifice steepness; (2) spatial distribution of vents, in turn related to the magmatic feeding system and the tectonic framework, which will control edifice plan shape; and (3) caldera formation, which will condition edifice truncation.

PWR upper/lower internals shield

Energy Technology Data Exchange (ETDEWEB)

Homyk, W.A. [Indian Point Station, Buchanan, NY (United States)

1995-03-01

During refueling of a nuclear power plant, the reactor upper internals must be removed from the reactor vessel to permit transfer of the fuel. The upper internals are stored in the flooded reactor cavity. Refueling personnel working in containment at a number of nuclear stations typically receive radiation exposure from a portion of the highly contaminated upper intervals package which extends above the normal water level of the refueling pool. This same issue exists with reactor lower internals withdrawn for inservice inspection activities. One solution to this problem is to provide adequate shielding of the unimmersed portion. The use of lead sheets or blankets for shielding of the protruding components would be time consuming and require more effort for installation since the shielding mass would need to be transported to a support structure over the refueling pool. A preferable approach is to use the existing shielding mass of the refueling pool water. A method of shielding was devised which would use a vacuum pump to draw refueling pool water into an inverted canister suspended over the upper internals to provide shielding from the normally exposed components. During the Spring 1993 refueling of Indian Point 2 (IP2), a prototype shield device was demonstrated. This shield consists of a cylindrical tank open at the bottom that is suspended over the refueling pool with I-beams. The lower lip of the tank is two feet below normal pool level. After installation, the air width of the natural shielding provided by the existing pool water. This paper describes the design, development, testing and demonstration of the prototype device.

Study and installation of concrete shielding in the civil engineering of nuclear construction (1960); Etude et mise en place des betons de protection dans le genie civil des ouvrages nucleaires (1960)

Energy Technology Data Exchange (ETDEWEB)

Dubois, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

The object of this report is to give technical information about high density concretes which have become very important for radiation biological shielding. The most generally used heavy aggregates (barytes, ilmenite, ferrophosphorus, limonite, magnetite and iron punching) to make these concretes are investigated from the point of view prospecting and physical and chemical characteristics. At first, a general survey of shielding concretes is made involving the study of components, mixing and placing methods, then, a detailed investigation of some high density concretes: barytes concrete, with incorporation of iron punching or iron shot, ferrophosphorus concrete, ilmenite concrete and magnetite concrete, more particularly with regard to grading and mix proportions and testing process. To put this survey in concrete form, two practical designs are described such as they have been carried out at the Saclay Nuclear Station. Specifications are given for diverse concretes and for making the proton-synchrotron 'Saturne' shielding blocks. (author) [French] Ce rapport a pour objet de donner des precisions techniques au sujet des betons a haute densite qui ont pris une grande importance pour la protection biologique contre les rayonnements. Les agregats lourds les plus couramment utilises (barytine, ilmenite, ferrophosphore, limonite, magnetite et riblons) pour la fabrication de ces betons, sont examines du point de vue prospection et caracteristiques physiques et chimiques. On procede d'abord a une etude generale des betons de protection comprenant l'etude des constituants, de la confection et de la mise en place, ensuite, a un examen detaille de quelques betons a haute densite: betons a base de barytine, avec incorporation de riblons ou de grenaille de fonte, betons au ferrophosphore, a base d'ilmenite ou de magnetite, notamment en ce qui concerne la granulometrie, la composition, le dosage et les processus d'essais. Pour concretiser ces etudes, deux applications pratiques

Shielding experiments for accelerator facilities

Energy Technology Data Exchange (ETDEWEB)

Nakashima, Hiroshi; Tanaka, Susumu; Sakamoto, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

2000-06-01

A series of shielding experiments was carried out by using AVF cyclotron accelerator of TIARA at JAERI in order to validate shielding design methods for accelerator facilities in intermediate energy region. In this paper neutron transmission experiment through thick shields and radiation streaming experiment through a labyrinth are reported. (author)

Shielding experiments for accelerator facilities

International Nuclear Information System (INIS)

Nakashima, Hiroshi; Tanaka, Susumu; Sakamoto, Yukio

2000-01-01

A series of shielding experiments was carried out by using AVF cyclotron accelerator of TIARA at JAERI in order to validate shielding design methods for accelerator facilities in intermediate energy region. In this paper neutron transmission experiment through thick shields and radiation streaming experiment through a labyrinth are reported. (author)

Nuclear data for radiation shielding

International Nuclear Information System (INIS)

Miyasaka, Shunichi; Takahashi, Hiroshi.

1976-01-01

The third shielding expert conference was convened in Paris in Oct. 1975 for exchanging informations about the sensitivity evaluation of nuclear data in shielding calculation and integral bench mark experiment. The requirements about nuclear data presented at present from the field of nuclear design do not reflect sufficiently the requirements of shielding design, therefore it was the object to gather the requirements about nuclear data from the field of shielding. The nuclides used for shielding are numerous, and the nuclear data on these isotopes are required. Some of them cannot be ignored as the source of secondary γ-ray or in view of the radioactivation of materials. The requirements for the nuclear data of neutrons in the field of shielding are those concerning the reaction cross sections producing secondary γ-ray, the reaction cross sections including the production of secondary neutrons, elastic scattering cross sections, and total cross sections. The topics in the Paris conference about neutron shielding data are described, such as the methodology of sensitivity evaluation, the standardization of group constant libraries, the bench mark experiment on iron and sodium, and the cross section of γ-ray production. In the shielding of nuclear fission reactors, the γ-ray production owing to nuclear fission reaction is also important. In (d, t) fusion reactors, high energy neutrons are generated, and high energy γ-ray is emitted through giant E1 resonance. (Kako, I.)

Optimization of multi-layered metallic shield

International Nuclear Information System (INIS)

Ben-Dor, G.; Dubinsky, A.; Elperin, T.

2011-01-01

Research highlights: → We investigated the problem of optimization of a multi-layered metallic shield. → The maximum ballistic limit velocity is a criterion of optimization. → The sequence of materials and the thicknesses of layers in the shield are varied. → The general problem is reduced to the problem of Geometric Programming. → Analytical solutions are obtained for two- and three-layered shields. - Abstract: We investigate the problem of optimization of multi-layered metallic shield whereby the goal is to determine the sequence of materials and the thicknesses of the layers that provide the maximum ballistic limit velocity of the shield. Optimization is performed under the following constraints: fixed areal density of the shield, the upper bound on the total thickness of the shield and the bounds on the thicknesses of the plates manufactured from every material. The problem is reduced to the problem of Geometric Programming which can be solved numerically using known methods. For the most interesting in practice cases of two-layered and three-layered shields the solution is obtained in the explicit analytical form.

SHIELD verification and validation report

International Nuclear Information System (INIS)

Boman, C.

1992-02-01

This document outlines the verification and validation effort for the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system code. Along with its predecessors, SHIELD has been in use at the Savannah River Site (SRS) for more than ten years. During this time the code has been extensively tested and a variety of validation documents have been issued. The primary function of this report is to specify the features and capabilities for which SHIELD is to be considered validated, and to reference the documents that establish the validation

Radiation shield for nuclear reactors

International Nuclear Information System (INIS)

Weissenfluh, J.A.

1978-01-01

A shield for use with nuclear reactor systems to attenuate radiation resulting from reactor operation is described. The shield comprises a container preferably of a thin, flexible or elastic material, which may be in the form of a bag, a mattress, a toroidal segment or toroid or the like filled with radiation attenuating liuid. Means are provided in the container for filling and draining the container in place. Due to its flexibility, the shield readily conforms to irregularities in surfaces with which it may be in contact in a shielding position

Practical high-density shielding materials for medical linear accelerator rooms

International Nuclear Information System (INIS)

Barish, R.J.

1990-01-01

High-energy linear accelerators are replacing lower energy units in radiation therapy centers. Radiation protection requirements necessitate expensive reconstruction of existing treatment rooms to accommodate these new machines. We describe two shielding materials: one made by embedding small pieces of scrap steel in cement, and the other made with cast iron in cement. Both materials produce high-density barriers at low cost using standard construction methods

Hybrid Active-Passive Radiation Shielding System

Data.gov (United States)

National Aeronautics and Space Administration — A radiation shielding system is proposed that integrates active magnetic fields with passive shielding materials. The objective is to increase the shielding...

Calculation of the neutrons shielding in cyclotron accelerator

International Nuclear Information System (INIS)

Ribeiro, Martha S.; Sanches, Matias P.; Rodrigues, Demerval L.

2000-01-01

The objective of radioprotection in cyclotron facilities is to reduce the dose levels in the workplaces to classify them like supervised areas. In this way, the radiation dose rates in areas occupied by workers during cyclotron operations should not exceed 7,5 μSv/h. In controlled areas these levels are not observed and some rigorous controls must be exerted by administrative procedures or protection mechanisms. The Cyclotron Laboratory at IPEN-CNEN/SP has a cyclotron model Cyclone 30, 30 MeV, used for research and it is also used for radioisotopes production for medical diagnosis and therapeutical applications. Among them, 123 I, 67 Ga and 18 F can be pointed. When accelerator is operating, failures in perforations and paths that conduce to room accelerator can be occur and thus, the dose levels are higher than that established by law. For this reason, a review for shielding structure was necessary in order to optimize radiation dose. The purpose of this work was to determine the shielding thickness and adequate material to diminish the dose rates in workplaces to a value below 7,5 μSv/h. It was used a method to employ the equivalent dose value in the facility areas for neutrons fluency rate for the principal reactions in target irradiation processes. The purposed shielding for the vault doors ensures dose levels lower than established limits to supervised areas. (author)

Topogram-based tube current modulation of head computed tomography for optimizing image quality while protecting the eye lens with shielding.

Science.gov (United States)

Lin, Ming-Fang; Chen, Chia-Yuen; Lee, Yuan-Hao; Li, Chia-Wei; Gerweck, Leo E; Wang, Hao; Chan, Wing P

2018-01-01

Background Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. Purpose To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. Material and Methods An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit. Image quality, assessed using regions of interest drawn on the bilateral extraorbital areas and the nasal bone with a water-based marker, was evaluated using both a signal-to-noise ratio (SNR) and contrast-noise ratio (CNR). Two CT specialists independently assessed image artifacts using a three-point Likert scale. Results The estimated radiation dose received by the lens was significantly lower when barium sulfate or bismuth-antimony shields were used in conjunction with a fixed tube current (22.0% and 35.6% reduction, respectively). Topogram-based TCM mitigated the beam hardening-associated artifacts of bismuth-antimony and barium sulfate shields. This increased the SNR by 21.6% in the extraorbital region and the CNR by 7.2% between the nasal bones and extraorbital regions. The combination of topogram-based TCM and barium sulfate or bismuth-antimony shields reduced lens doses by 12.2% and 27.2%, respectively. Conclusion Image artifacts induced by the bismuth-antimony shield at a fixed tube current for lenticular radioprotection were significantly reduced by topogram-based TCM, which increased the SNR of the anthropomorphic nasal bones and periorbital tissues.

UVB shielding role of FeCl3 and certain cyanobacterial pigments

International Nuclear Information System (INIS)

Kumar, A.; Tyagi, M.B.; Srinivas, G.; Singh, N.; Kumar, H.D.; Sinha, R.P.; Friedrich-Alexander-Universitaet, Erlangen; Haeder, D.P.

1996-01-01

The shielding role of ferric iron (FeCl 3 ) and certain cyanobacterial pigments (a brown-colored pigment from Scytonema hofmanii culture filtrate and a pink extract from Nostoc spongiaeforme) against UVB-induced damage in the filamentous, nitrogen-fixing cyanobacterium Nostoc muscorum has been demonstrated. Addition of these colored compounds to agarose gels (1-3 mm thick) resulted in a considerable decrease in UVB transmittance through the gels. The lowest UVB transmittance (15%) occurred through a 3 mm gel containing 0.01% FeCl 3 , followed by S. hofmanii culture filtrate (40%) and N. spongiaeforme extract (50%). These substances appear to act as very efficient UVB-absorbing screens. Percent survival and 14 CO 2 uptake of N. muscorum increased significantly if UVB exposure was given on gels containing FeCl 3 or other UVB-shielding substances. The highest protection of N. muscorum was recorded with FeCl 3 , followed by S. hofmanii culture filtrate and N. spongiaeforme extract. Such UV-shielding substances if present in required concentration range may enhance the survival of cyanobacteria exposed to high levels of UVB. (author)

Shielding design of highly activated sample storage at reactor TRIGA PUSPATI

International Nuclear Information System (INIS)

Naim Syauqi Hamzah; Julia Abdul Karim; Mohamad Hairie Rabir; Muhd Husamuddin Abdul Khalil; Mohd Amin Sharifuldin Salleh

2010-01-01

Radiation protection has always been one of the most important things considered in Reaktor Triga PUSPATI (RTP) management. Currently, demands on sample activation were increased from variety of applicant in different research field area. Radiological hazard may occur if the samples evaluation done were misjudge or miscalculated. At present, there is no appropriate storage for highly activated samples. For that purpose, special irradiated samples storage box should be provided in order to segregate highly activated samples that produce high dose level and typical activated samples that produce lower dose level (1 - 2 mR/ hr). In this study, thickness required by common shielding material such as lead and concrete to reduce highly activated radiotracer sample (potassium bromide) with initial exposure dose of 5 R/ hr to background level (0.05 mR/ hr) were determined. Analyses were done using several methods including conventional shielding equation, half value layer calculation and Micro shield computer code. Design of new irradiated samples storage box for RTP that capable to contain high level gamma radioactivity were then proposed. (author)

Radiation safety aspects during nondestructive testing of reactor shielding components by gamma radiometry

International Nuclear Information System (INIS)

Viswanathan, S.; Jose, M.T.; Venkatraman, B.

2016-01-01

In nuclear facilities, effective shielding of radioactive components and structures are essential to ensure radiation protection to operating personnel. The shield structures are made of lead, steel and concrete with varying thickness of up to 1200 mm. It needs to be verified for shielding integrity, presence of voids, blowholes and defects to avoid exposure to workers and to public at large. Radiometry using gamma source serves as excellent tool for non-destructive examination of such structures and components. Gamma sources of high activity up to 50 Curies (gamma camera type) depending on the thickness of component have to be used. During the testing exposure to the operating personnel needs to be minimized, this requires certain safety procedures to be followed. This paper focuses the methodology to be adapted by means of selection of source, effective training of personnel, compliance with safety requirements and maintenance of source devices

Experimental simulation and numerical modeling of vapor shield formation and divertor material erosion for ITER typical plasma disruptions

International Nuclear Information System (INIS)

Wuerz, H.; Arkhipov, N.I.; Bakhtin, V.P.; Konkashbaev, I.; Landman, I.; Safronov, V.M.; Toporkov, D.A.; Zhitlukhin, A.M.

1995-01-01

The high divertor heat load during a tokamak plasma disruption results in sudden evaporation of a thin layer of divertor plate material, which acts as vapor shield and protects the target from further excessive evaporation. Formation and effectiveness of the vapor shield are theoretically modeled and are experimentally analyzed at the 2MK-200 facility under conditions simulating the thermal quench phase of ITER tokamak plasma disruptions. ((orig.))

Handout on shielding calculation

International Nuclear Information System (INIS)

Heilbron Filho, P.F.L.

1991-01-01

In order to avoid the difficulties of the radioprotection supervisors in the tasks related to shielding calculations, is presented in this paper the basic concepts of shielding theory. It also includes exercises and examples. (author)

Pretinning Nickel-Plated Wire Shields

Science.gov (United States)

Igawa, J. A.

1985-01-01

Nickel-plated copper shielding for wires pretinned for subsequent soldering with help of activated rosin flux. Shield cut at point 0.25 to 0.375 in. (6 to 10 mm) from cut end of outer jacket. Loosened end of shield straightened and pulled toward cut end. Insulation of inner wires kept intact during pretinning.

Radiation Shielding Materials and Containers Incorporating Same

Energy Technology Data Exchange (ETDEWEB)

Mirsky, Steven M.; Krill, Stephen J.; and Murray, Alexander P.

2005-11-01

An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (''PYRUC'') shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

Investigation of factors influencing the efficacy of electromagnetic shielding in X band frequency range

Directory of Open Access Journals (Sweden)

Vida Zaroushani

2016-12-01

/nickel oxide composite can represents a new generation of electromagnetic shielding, which is considered as a promising candidate for occupational protection against microwave exposure. It is recommended that future studies improve the shielding effectiveness by decreasing the percolation depth and investigate the efficacy of the fabricated shield in the workplaces.

Quality control, mean glandular dose estimate and room shielding calculation in mammography

International Nuclear Information System (INIS)

Rakotomalala, H.M.

2014-01-01

This study focuses in the importance of Radiation Protection in mammography. A good control of the radiological risk depends on the dose optimization, room shielding calculation and the quality of equipment. The work was carried out in the three private medical centers called A, B, and C. Dosimetry estimates were made on the equipment of the three centers. Values has been compared with the Diagnostic Reference Levels established by the International Atomic Energy Agency (IAEA). Conformity control of the radiological devices has also been done with the Mammographic Quality Control Kit of the INSTN-Madagascar. Verifications of shields of the room containing the mammography equipment were done by theoretical calculations using the method provided by NCRP 147. [fr

Shielding technology for high energy radiation production facility

International Nuclear Information System (INIS)

Lee, Byung Chul; Kim, Heon Il

2004-06-01

In order to develop shielding technology for high energy radiation production facility, references and data for high energy neutron shielding are searched and collected, and calculations to obtain the characteristics of neutron shield materials are performed. For the evaluation of characteristics of neutron shield material, it is chosen not only general shield materials such as concrete, polyethylene, etc., but also KAERI developed neutron shields of High Density PolyEthylene (HDPE) mixed with boron compound (B 2 O 3 , H 2 BO 3 , Borax). Neutron attenuation coefficients for these materials are obtained for later use in shielding design. The effect of source shape and source angular distribution on the shielding characteristics for several shield materials is examined. This effect can contribute to create shielding concept in case of no detail source information. It is also evaluated the effect of the arrangement of shield materials using current shield materials. With these results, conceptual shielding design for PET cyclotron is performed. The shielding composite using HDPE and concrete is selected to meet the target dose rate outside the composite, and the dose evaluation is performed by configuring the facility room conceptually. From the result, the proper shield configuration for this PET cyclotron is proposed

Hybrid Magnetic Shielding

Science.gov (United States)

Royal, Kevin; Crawford, Christopher; Mullins, Andrew; Porter, Greg; Blanton, Hunter; Johnstone, Connor; Kistler, Ben; Olivera, Daniela

2017-09-01

The search for the electric dipole moment of the neutron requires the ambient magnetic field to be on the pT scale which is accomplished with large magnetic shielding rooms. These rooms are fitted with large mu-metal sheets to allow for passive cancellation of background magnetic fields. Active shielding technology cannot uniformly cancel background magnetic fields. These issues can be remedied by combining the methods into a hybrid system. The design used is composed of panels that have an active layer of cancellation between two sheets of mu-metal. The panels form a cube and draw in magnetic fields perpendicular to the surface which can then be reduced using active shielding. This work is supported by the Department of Energy under Contract DE-SC0008107.

Modular reactor head shielding system

International Nuclear Information System (INIS)

Jacobson, E. B.

1985-01-01

An improved modular reactor head shielding system is provided that includes a frame which is removably assembled on a reactor head such that no structural or mechanical alteration of the head is required. The shielding system also includes hanging assemblies to mount flexible shielding pads on trolleys which can be moved along the frame. The assemblies allow individual pivoting movement of the pads. The pivoting movement along with the movement allowed by the trolleys provides ease of access to any point on the reactor head. The assemblies also facilitate safe and efficient mounting of the pads directly to and from storage containers such that workers have additional shielding throughout virtually the entire installation and removal process. The flexible shielding pads are designed to interleave with one another when assembled around the reactor head for substantially improved containment of radiation leakage

Mechanical shielded hot cell

International Nuclear Information System (INIS)

Higgy, H.R.; Abdel-Rassoul, A.A.

1983-01-01

A plan to erect a mechanical shielded hot cell in the process hall of the Radiochemical Laboratory at Inchas is described. The hot cell is designed for safe handling of spent fuel bundles, from the Inchas reactor, and for dismantling and cutting the fuel rods in preparation for subsequent treatment. The biological shielding allows for the safe handling of a total radioactivity level up to 10,000 MeV-Ci. The hot cell consists of an α-tight stainless-steel box, connected to a γ-shielded SAS, through an air-lock containing a movable carriage. The α-box is tightly connected with six dry-storage cavities for adequate storage of the spent fuel bundles. Both the α-box, with the dry-storage cavities, and the SAS are surrounded by 200-mm thick biological lead shielding. The α-box is equipped with two master-slave manipulators, a lead-glass window, a monorail crane and Padirac and Minirag systems. The SAS is equipped with a lead-glass window, tong manipulator, a shielded pit and a mechanism for the entry of the spent fuel bundle. The hot cell is served by adequate ventilation and monitoring systems. (author)

Radiation shielding

International Nuclear Information System (INIS)

Aitken, D.

1979-01-01

Shields for equipment in which ionising radiation is associated with high electrical gradients, for example X-ray tubes and particle accelerators, incorporate a radiation-absorbing metal, as such or as a compound, and are electrically non-conducting and can be placed in the high electrical gradient region of the equipment. Substances disclosed include dispersions of lead, tungsten, uranium or oxides of these in acrylics polyesters, PVC, ABS, polyamides, PTFE, epoxy resins, glass or ceramics. The material used may constitute an evacuable enclosure of the equipment or may be an external shield thereof. (U.K.)

Radiation protection to the eye and thyroid during diagnostic cerebral angiography: a phantom study.

LENUS (Irish Health Repository)

Shortt, C P

2008-08-01

We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

Radiation protection to the eye and thyroid during diagnostic cerebral angiography : a phantom study

International Nuclear Information System (INIS)

Shortt, C. P.; Malone, L.; Thornton, J.; Brennan, P.; Lee, M. J.

2008-01-01

Full text: We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

Manual on radiation protection in hospitals and general practice. Basic protection requirements

International Nuclear Information System (INIS)

Braestrup, C.B.; Vikterloef, K.J.

1974-01-01

The manual as a whole deals with the radiation protection of patients, occupationally exposed persons, and the public. Volume 1, on basic protection requirements, is a general review common to all medical applications of ionizing radiation and radionuclides. Radiation protection is required for patients and staff, and with regard to medical research and chemical trials of new methods; radiation equipment and operating procedures are discussed in connection with diagnostic x-ray installations, x-ray beam therapy, gamma-ray installations for teletherapy, brachytherapy, unsealed sources for therapeutic use, and the diagnostic use of unsealed sources in nuclear medicine. In planning of radiation facilities, attention is paid to levels at which medical care is given, the centralization and decentralization of radiation facilities, diagnostic x-ray facilities and therapy facilities, and nuclear medicine and therapy with unsealed sources. Shielding design is discussed applicable to diagnostic radiology, radiotherapy, nuclear medicine and the therapeutic use of radionuclides. Assignment of responsibilities, legal responsibilities, safety checks, refresher courses and symposia are discussed in the context of organizing radiation protection. Radiation surveys are necessary, and such surveys are described for x-ray and gamma-ray beams, sealed radioactive sources and nuclear medicine. A whole section is devoted to personnel monitoring and health surveillance. An annex gives a list of commonly used radionuclides, another deals with the design of protective shielding

Development of a computational code for calculations of shielding in dental facilities

International Nuclear Information System (INIS)

Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Guimaraes, Antonio C.F.; Moreira, Maria de L.

2014-01-01

This paper is prepared in order to address calculations of shielding to minimize the interaction of patients with ionizing radiation and / or personnel. The work includes the use of protection report Radiation in Dental Medicine (NCRP-145 or Radiation Protection in Dentistry), which establishes calculations and standards to be adopted to ensure safety to those who may be exposed to ionizing radiation in dental facilities, according to the dose limits established by CNEN-NN-3.1 standard published in September / 2011. The methodology comprises the use of computer language for processing data provided by that report, and a commercial application used for creating residential projects and decoration. The FORTRAN language was adopted as a method for application to a real case. The result is a programming capable of returning data related to the thickness of material, such as steel, lead, wood, glass, plaster, acrylic, acrylic and leaded glass, which can be used for effective shielding against single or continuous pulse beams. Several variables are used to calculate the thickness of the shield, as: number of films used in the week, film load, use factor, occupational factor, distance between the wall and the source, transmission factor, workload, area definition, beam intensity, intraoral and panoramic exam. Before the application of the methodology is made a validation of results with examples provided by NCRP-145. The calculations redone from the examples provide answers consistent with the report

Computed tomography shielding methods: a literature review.

Science.gov (United States)

Curtis, Jessica Ryann

2010-01-01

To investigate available shielding methods in an effort to further awareness and understanding of existing preventive measures related to patient exposure in computed tomography (CT) scanning. Searches were conducted to locate literature discussing the effectiveness of commercially available shields. Literature containing information regarding breast, gonad, eye and thyroid shielding was identified. Because of rapidly advancing technology, the selection of articles was limited to those published within the past 5 years. The selected studies were examined using the following topics as guidelines: the effectiveness of the shield (percentage of dose reduction), the shield's effect on image quality, arguments for or against its use (including practicality) and overall recommendation for its use in clinical practice. Only a limited number of studies have been performed on the use of shields for the eyes, thyroid and gonads, but the evidence shows an overall benefit to their use. Breast shielding has been the most studied shielding method, with consistent agreement throughout the literature on its effectiveness at reducing radiation dose. The effect of shielding on image quality was not remarkable in a majority of studies. Although it is noted that more studies need to be conducted regarding the impact on image quality, the currently published literature stresses the importance of shielding in reducing dose. Commercially available shields for the breast, thyroid, eyes and gonads should be implemented in clinical practice. Further research is needed to ascertain the prevalence of shielding in the clinical setting.

Radiation shielding cloth

International Nuclear Information System (INIS)

Ijiri, Yasuo; Fujinuma, Tadashi; Tamura, Shoji.

1989-01-01

Radiation shielding cloth having radiation shielding layers comprising a composition of inorganic powder of high specific gravity and rubber are excellentin flexibility and comfortable to put on. However, since they are heavy in the weight, operators are tired upon putting them for a long time. In view of the above, the radiation ray shielding layers are prepared by calendering sheets obtained by preliminary molding of the composition to set the variation of the thickness within a range of +15% to -0% of prescribed thickness. Since the composition of inorganic powder at high specific gravity and rubber used for radiation ray shielding comprises a great amount of inorganic powder at high specific gravity blended therein, it is generally poor in fabricability. Therefor, it is difficult to attain fine control for the sheet thickness by merely molding a composition block at once. Then, the composition is at first preliminarily molded into a sheet-like shape which is somewhat thickener than the final thickness and then finished by calendering, by which the thickness can be reduced in average as compared with conventional products while keeping the prescribed thickness and reducing the weight reduce by so much. (N.H.)

Radiation shielding glass

International Nuclear Information System (INIS)

Kido, Kazuhiro; Ueda, Hajime.

1997-01-01

It was found that a glass composition comprising, as essential ingredients, SiO 2 , PbO, Gd 2 O 3 and alkali metal oxides can provide a shielding performance against electromagnetic waves, charged particles and neutrons. The present invention provides radiation shielding glass containing at least from 16 to 46wt% of SiO 2 , from 47 to 75wt% of PbO, from 1 to 10wt% of Gd 2 O 3 , from 0 to 3wt% of Li 2 O, from 0 to 7wt% of Na 2 O, from 0 to 7wt% of K 2 O provided that Li 2 O + Na 2 O + K 2 O is from 1 to 10wt%, B 2 O 3 is from 0 to 10wt%, CeO 2 is from 0 to 3wt%, As 2 O 3 is from 0 to 1wt% and Sb 2 O 3 is from 0 to 1wt%. Since the glass can shield electromagnetic waves, charged particles and neutrons simultaneously, radiation shielding windows can be designed and manufactured at a reduced thickness and by less constitutional numbers in a circumstance where they are present altogether. (T.M.)

Use of polyethylene pellets in the design and construction of a storage safe, a transport vessel and a portable shield for californium-252

International Nuclear Information System (INIS)

Sharma, S.

1986-01-01

A storage and shielding facility for 300 μg of Californium-252 sources was designed and constructed. Though the safe was in a permanent location, the fact that it consisted of a lead bucket surrounded by polyethylene pellets made it simple, movable and inexpensive. If need be, more quantities of Cf-252 could be added without altering the basic design and sacrificing the radiation protection guidelines. The measured radiation levels from 300 μg of stored Cf-252 in and around the storage vault were lower than the expected dose rates by a factor of 5. The measured radiation levels around the occupied environs of the facility were below the maximum permissible yearly dose of 500mrem for non-occupational workers. A transport vessel was designed and constructed to carry up to 50 μg of Californium-252 sources. It consisted of a standard 55 gallon steel drum on casters containing cylindrical lead shield surrounded by polyethylene pellets. The measured maximum surface dose rates on the drum and at one meter away were within the radiation protection guidelines and were less than the expected dose rates. A portable shield was designed and constructed to protect the body in afterloading operations and handling of the sources. It consisted of polyethylene pellets in an aluminum box and an attached 10 cm thick plexiglass eye shield. The simple design, with the ease of using polyethylene pellets can be extended to construct bedside shields

Shield design of concrete wall between decay tank room and primary pump room in TRIGA facility

International Nuclear Information System (INIS)

Khan, M. J. H.; Rahman, M.; Haque, A.; Zulquarnain, A.; Ahmed, F. U.; Bhuiyan, S. I.

2007-01-01

The objective of this study is to recommend the radiation protection design parameters from the shielding point of view for concrete wall between the decay tank room and the primary pump room in TRIGA Mark-II research reactor facility. The shield design for this concrete wall has been performed with the help of Point-kernel Shielding Code Micro-Shield 5.05 and this design was also validated based on the measured dose rate values with Radiation Survey Meter (G-M Counter) considering the ICRP-60 (1990) recommendations for occupational dose rate limit (10 μSv/hr). The recommended shield design parameters are: (i) thickness of 114.3 cm Ilmenite-Magnetite Concrete (IMC) or 129.54 cm Ordinary Reinforced Concrete (ORC) for concrete wall A (ii) thickness of 66.04 cm Ilmenite-Magnetite Concrete (IMC) or 78.74 cm Ordinary Reinforced Concrete (ORC) for concrete wall B and (iii) door thickness of 3.175 cm Mild Steel (MS) on the entrance of decay tank room. In shielding efficiency analysis, the use of I-M concrete in the design of this concrete wall shows that it reduced the dose rate by a factor of at least 3.52 times approximately compared to ordinary reinforced concrete

Shielding modification design of the N.S. Mutsu

International Nuclear Information System (INIS)

Yamaji, A.; Miyakoshi, J.; Kageyama, T.; Futamura, Y.

1983-01-01

Shielding modification design of the N.S. Mutsu was performed for reducing the radiation doses outside the primary and the secondary shields by providing shields for neutrons streaming through the air gap between the pressure vessel and the primary shield. This was accomplished by replacing parts of the shields and adding new shields in the upper and lower sections of both primary and secondary shields, and also replacing the thermal insulator in the gap. The shielding design calculations were made using one- and two-dimensional discrete ordinates codes and also a point kernel code. Special attention was paid to the calculations of, (1) the neutrons streaming through the gap between the pressure vessel and the primary shield, (2) the radiations transmitted through the radial shield of the core in the primary shield, (3) the radiations transmitted through the upper and lower sections of the secondary shield, and (4) the dose rate equivalent in the accommodation area. Their calculational accuracies were estimated by analyzing various experiments. To support the modification, a variety of experiments and tests were carried out, which were material tests, cooling test of the primary shield, mechanical strength test of the double bottom, trial fabrication tests of new shields, performance degradation test of heavy concrete and duct streaming experiment in the secondary shield. (author)

Assessment in hygiene and radiation protection in use of shielded laminar flow hoods; Bilan en matiere d'hygiene et de radioprotection de l'utilisation de hottes blindees a flux laminaire

Energy Technology Data Exchange (ETDEWEB)

Bouquey, C.; Roudaut, M.; Pommier, M.; Lortal, B. [Institut Bergonie, Service de pharmacie, 33 - Bordeaux (France); Cazaux, A.L. [Institut Bergonie, Service de medecine nucleaire, 33 - Bordeaux (France)

2010-07-01

Radiopharmacy Bergonie institute has grown in 2008, on this occasion, shielded enclosures have been changed. The choice fell on new technologies taking into account the problems of radiation protection and bacterial contamination. We chose laminar flow hoods for achieving the prescription of radiopharmaceuticals in an aseptic environment and full automation of samples of the dose of F.D.G.. we have undertaken a review of performance of this material in sterility, radiation protection and reliability. conclusions: we reconcile our need to optimize radiation protection of manipulators while respecting the constraints of health described in the good practices of preparation (G.P.P.). However, a new problem arises, how do manage electronic and computer quickly without service organization be not perturbed. (N.C.)

Radiation shielding curtain

International Nuclear Information System (INIS)

Winkler, N.T.

1976-01-01

A radiation shield is described in the form of a stranded curtain made up of bead-chains whose material and geometry are selected to produce a cross-sectional density that is the equivalent of 0.25 mm or more of lead and which curtain may be mounted on various radiological devices to shield against scattered radiation while offering a minimum of obstruction to the radiologist

Method for limiting movement of a thermal shield for a nuclear reactor, and thermal shield displacement limiter therefor

International Nuclear Information System (INIS)

Meuschke, R.E.; Boyd, C.H.

1989-01-01

This patent describes a method of limiting the movement of a thermal shield of a nuclear reactor. It comprises: machining at least four (4) pockets in upper portions of a thermal shield circumferentially about a core barrel of a nuclear reactor to receive key-wave inserts; tapping bolt holes in the pockets of the thermal shield to receive bolts; positioning key-wave inserts into the pockets of the thermal shield to be bolted in place with the bolt holes; machining dowel holes at least partially through the positioned key-way inserts and the thermal shield to receive dowel pins; positioning dowel pins in the dowel holes in the key-way insert and thermal shield to tangentially restrain movement of the thermal shield relative to the core barrel; sliding limiter keys into the key-way inserts and bolting the limiter keys to the core barrel to tangentially restrain movement of the thermal shield relative and the core barrel while allowing radial and axial movement of the thermal shield relative to the core barrel; machining dowel holes through the limiter key and at least partially through the core barrel to receive dowel pins; positioning dowel pins in the dowel holes in the limiter key and core barrel to restrain tangential movement of the thermal shield relative to the core barrel of the nuclear reactor

Methods and experimental coefficients used in the computation of reactor shielding; Methodes et coefficients experimentaux pour le calcul des protections de reacteurs

Energy Technology Data Exchange (ETDEWEB)

Bourgeois, J; Lafore, P; Millot, J P; Rastoin, J; Vathaire, F de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

1) The concept of an effective removal cross section has been developed in order more easily to compute reactor shielding thicknesses. We have built an experimental facility for the purpose of measuring effective removal cross sections, the value of which had not been published at that time. The first part of this paper describes the device or facility used, the computation method applied, and the results obtained. 2) Starting from this concept, we endeavoured to define a removal cross section as a function of energy. This enabled us to use the method for computations bearing on the attenuation of fast neutrons of any spectrum. An experimental verification was carried out for the case of fission neutrons filtered by a substantial thickness of graphite. 3) Finally, we outline a computation method enabling us to determine the sources of captured gamma rays by the age theory and we give an example of the application in a composite shield. (author) [French] 1) La notion de section efficace effective de deplacement a ete introduite pour calculer commodement les epaisseurs de protection des reacteurs. Nous avons construit un dispositif experimental destine a mesurer les sections efficaces effectives de deplacement dont la valeur n'avait pas ete publiee a cette epoque. La premiere partie de cette communication decrit le dispositif utilise, la methode de calcul employee et les resultats obtenus. 2) A partir de cette notion, nous avons essaye de definir une section efficace de deplacement fonction de l'energie. Ceci permet d'utiliser la methode du deplacement pour des calculs d'attenuation de neutrons rapides dont le spectre est quelconque. Une verification experimentale a ete faite dans le cas de neutrons de fission filtres par une epaisseur notable de graphite. 3) Enfin une methode de calcul permettant de determiner les sources de gamma de capture par la theorie de l'age est exposee et un exemple d'application donne dans une protection composite. (auteur)

Methods and experimental coefficients used in the computation of reactor shielding; Methodes et coefficients experimentaux pour le calcul des protections de reacteurs

Energy Technology Data Exchange (ETDEWEB)

Bourgeois, J; Lafore, P; Millot, J P; Rastoin, J; Vathaire, F de [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

1. The concept of an effective removal cross section has been developed in order more easily to compute reactor shielding thicknesses. We have built an experimental facility for the purpose of measuring effective removal cross sections, the value of which had not been published at that time. The first part of this paper describes the device or facility used, the computation method applied, and the results obtained. 2. Starting from this concept, we endeavored to define a removal cross section as a function of energy. This enabled us to use the method for computations bearing on the attenuation of fast neutrons of any spectrum. An experimental verification was carried out for the case of fission neutrons filtered by a substantial thickness of graphite. 3. Finally, we outline a computation method enabling us to determine the sources of captured gamma rays by the age theory and we give an example of the application in a composite shield. (author)Fren. [French] 1. La notion de section efficace effective de deplacement a ete introduite pour calculer commodement les epaisseurs de protection des reacteurs. Nous avons construit un dispositif experimental destine a mesurer les sections efficaces effectives de deplacement dont la valeur n'avait pas ete publiee a cette epoque. La premiere partie de cette communication decrit le dispositif utilise, la methode de calcul employee et les resultats obtenus. 2. A partir de cette notion, nous avons essaye de definir une section efficace de deplacement fonction de l'energie. Ceci permet d'utiliser la methode du deplacement pour des calculs d'attenuation de neutrons rapides dont le spectre est quelconque. Une verification experimentale a ete faite dans le cas de neutrons de fission filtres par une epaisseur notable de graphite. 3. Enfin une mde de calcul permettant de determiner les sources de gamma de capture par la theorie de l'age est exposee et un exemple d'application donne dans une protection composite. (auteur)

Welding shield for coupling heaters

Science.gov (United States)

Menotti, James Louis

2010-03-09

Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.

Several problems in accelerator shielding study

International Nuclear Information System (INIS)

Nakamura, Takashi; Hirayama, Hideo; Ban, Shuichi.

1980-01-01

Recently, the utilization of accelerators has increased rapidly, and the increase of accelerating energy and beam intensity is also remarkable. The studies on accelerator shielding have become important, because the amount of radiation emitted from accelerators increased, the regulation of the dose of environmental radiation was tightened, and the cost of constructing shielding rose. As the plans of constructing large accelerators have been made successively, the survey on the present state and the problems of the studies on accelerator shielding was carried out. Accelerators are classified into electron accelerators and proton accelerators in view of the studies on shielding. In order to start the studies on accelerator shielding, first, the preparation of the cross section data is indispensable. The cross sections for generating Bremsstrahlung, photonuclear reactions generating neutrons, generation of neutrons by hadrons, nuclear reaction of neutrons and generation of gamma-ray by hadrons are described. The generation of neutrons and gamma-ray as the problems of thick targets is explained. The shielding problems are complex and diversified, but in this paper, the studies on the shielding, by which basic data are obtainable, are taken up, such as beam damping and side wall shielding. As for residual radioactivity, main nuclides and the difference of residual radioactivity according to substances have been studied. (J.P.N.)

Shielding concerns at a spallation source

International Nuclear Information System (INIS)

Russell, G.J.; Robinson, H.; Legate, G.L.; Woods, R.

1989-01-01

Neutrons produced by 800-MeV proton reactions at the Los Alamos Neutron Scattering Center spallation neutron source cause a variety of challenging shielding problems. We identify several characteristics distinctly different from reactor shielding and compute the dose attenuation through an infinite slab/shield composed of iron (100 cm) and borated polyethylene (15 cm). Our calculations show that (for an incident spallation spectrum characteristic of neutrons leaking from a tungsten target at 90/degree/) the dose through the shield is a complex mixture of neutrons and gamma rays. High-energy (> 20 MeV) neutron production from the target is ≅5% of the total, yet causes ≅68% of the dose at the shield surface. Primary low-energy (< 20 MeV) neutrons from the target contribute negligibly (≅0.5%) to the dose at the shield surface yet cause gamma rays, which contribute ≅31% to the total dose at the shield surface. Low-energy neutrons from spallation reactions behave similarly to neutrons with a fission spectrum distribution. 6 refs., 8 figs., 1 tab

Highly heat removing radiation shielding material

International Nuclear Information System (INIS)

Asano, Norio; Hozumi, Masahiro.

1990-01-01

Organic materials, inorganic materials or metals having excellent radiation shielding performance are impregnated into expanded metal materials, such as Al, Cu or Mg, having high heat conductivity. Further, the porosity of the expanded metals and combination of the expanded metals and the materials to be impregnated are changed depending on the purpose. Further, a plurality of shielding materials are impregnated into the expanded metal of the same kind, to constitute shielding materials. In such shielding materials, impregnated materials provide shielding performance against radiation rays such as neutrons and gamma rays, the expanded metals provide heat removing performance respectively and they act as shielding materials having heat removing performance as a whole. Accordingly, problems of non-informity and discontinuity in the prior art can be dissolved be provide materials having flexibility in view of fabrication work. (T.M.)

Gonadal Shielding in Radiography: A Best Practice?

Science.gov (United States)

Fauber, Terri L

2016-11-01

To investigate radiation dose to phantom testes with and without shielding. A male anthropomorphic pelvis phantom was imaged with thermoluminescent dosimeters (TLDs) placed in the right and left detector holes corresponding to the testes. Ten exposures were made of the pelvis with and without shielding. The exposed TLDs were packaged securely and mailed to the University of Wisconsin Calibration Laboratory for reading and analysis. A t test was calculated for the 2 exposure groups (no shield and shielded) and found to be significant, F = 8.306, P shield was used during pelvic imaging. Using a flat contact shield during imaging of the adult male pelvis significantly reduces radiation dose to the testes. Regardless of the contradictions in the literature on gonadal shielding, the routine practice of shielding adult male gonads during radiographic imaging of the pelvis is a best practice. © 2016 American Society of Radiologic Technologists.

Estimating ISABELLE shielding requirements

International Nuclear Information System (INIS)

Stevens, A.J.; Thorndike, A.M.

1976-01-01

Estimates were made of the shielding thicknesses required at various points around the ISABELLE ring. Both hadron and muon requirements are considered. Radiation levels at the outside of the shield and at the BNL site boundary are kept at or below 1000 mrem per year and 5 mrem/year respectively. Muon requirements are based on the Wang formula for pion spectra, and the hadron requirements on the hadron cascade program CYLKAZ of Ranft. A muon shield thickness of 77 meters of sand is indicated outside the ring in one area, and hadron shields equivalent to from 2.7 to 5.6 meters in thickness of sand above the ring. The suggested safety allowance would increase these values to 86 meters and 4.0 to 7.2 meters respectively. There are many uncertainties in such estimates, but these last figures are considered to be rather conservative

Selective shielding device for scintiphotography

International Nuclear Information System (INIS)

Harper, J.W.; Kay, T.D.

1976-01-01

A selective shielding device to be used in combination with a scintillation camera is described. The shielding device is a substantially oval-shaped configuration removably secured to the scintillation camera. As a result of this combination scanning of preselected areas of a patient can be rapidly and accurately performed without the requirement of mounting any type of shielding paraphernalia on the patient. 1 claim, 2 drawing figures

Radiation shielding material

International Nuclear Information System (INIS)

Matsumoto, Akio; Isobe, Eiji.

1976-01-01

Purpose: To increase the shielding capacity of the radiation shielding material having an abundant flexibility. Constitution: A mat consisting of a lead or lead alloy fibrous material is covered with a cloth, and the two are made integral by sewing in a kilted fashion by using a yarn. Thereafter, the system is covered with a gas-tight film or sheet. The shielding material obtained in this way has, in addition to the above merits, advantages in that (1) it is free from restoration due to elasticity so that it can readily seal contaminants, (2) it can be used in a state consisting of a number of overlapped layers, (3) it fits the shoulder well and is readily portable and (4) it permits attachment of fasteners or the like. (Ikeda, J.)

Designing 4H-SiC P-shielding trench gate MOSFET to optimize on-off electrical characteristics

Science.gov (United States)

Kyoung, Sinsu; Hong, Young-sung; Lee, Myung-hwan; Nam, Tae-jin

2018-02-01

In order to enhance specific on-resistance (Ron,sp), the trench gate structure was also introduced into 4H-SiC MOSFET as Si MOSFET. But the 4H-SiC trench gate has worse off-state characteristics than the Si trench gate due to the incomplete gate oxidation process (Šimonka et al., 2017). In order to overcome this problem, P-shielding trench gate MOSFET (TMOS) was proposed and researched in previous studies. But P-shielding has to be designed with minimum design rule in order to protect gate oxide effectively. P-shielding TMOS also has the drawback of on-state characteristics degradation corresponding to off state improvement for minimum design rule. Therefore optimized design is needed to satisfy both on and off characteristics. In this paper, the design parameters were analyzed and optimized so that the 4H-SiC P-shielding TMOS satisfies both on and off characteristics. Design limitations were proposed such that P-shielding is able to defend the gate oxide. The P-shielding layer should have the proper junction depth and concentration to defend the electric field to gate oxide during the off-state. However, overmuch P-shielding junction depth disturbs the on-state current flow, a problem which can be solved by increasing the trench depth. As trench depth increases, however, the breakdown voltage decreases. Therefore, trench depth should be designed with due consideration for on-off characteristics. For this, design conditions and modeling were proposed which allow P-shielding to operate without degradation of on-state characteristics. Based on this proposed model, the 1200 V 4H-SiC P-shielding trench gate MOSFET was designed and optimized.

Development of X-ray protective clothes for medical treatments

International Nuclear Information System (INIS)

Nagai, M.; Koike, K.; Fujinuma, T.; Aso, T.; Konba, T.

1991-01-01

As various medical treatments using X-ray irradiation are getting more important in modern medicine, effective, excellent X-ray protective clothes have been required. Elastomeric or PVC sheets containing powdery lead are usually employed as conventional X-ray protective clothes. In this case, enhancement of X-ray shielding efficiency increases the weight because the efficiency depends on the amount of lead incorporated. Such heavy clothes give significant fatigue and inconvenience during long term use. Consequently, lightweight and comfortable X-ray protective clothes have been eagerly desired in the medical field. The authors have improved these defects in the conventional clothes by means of elastomeric blending technologies and successfully developed new, lightweight and comfortable X-ray shielding clothes. The new clothes consist of lead-containing rubber sheet in which lead is homogeneously incorporated and lightweight PVC laminated with fabrics. They achieved favorable sense of touch, comfortable wearing and long-term durability. Furthermore, the clothes satisfy all requirements including X-ray shielding efficiency defined in JIS specifications. This article introduces the development of the new clothes and their properties in detail. (author)

Shielding analysis in the design phase of the new Emergency Operation Facility for Tihange Nuclear Power Plant

OpenAIRE

Genard Gilles; Portal Romain; Bouchat Virginie; Vanderperre Serge

2017-01-01

In the framework of the design studies for a new Emergency Operation Facility (EOF) for Tihange NPP, radiation protection analyses are needed to comply with effective dose rate criteria. In this aim, the shielding performed by, at the one hand, external walls and roof of the building and, on the other hand, internal walls, has been sized by means of MicroShield calculations. This paper explains how the calculations for external walls, doors, roof, floor and internal walls are made. The assump...

Shielding effectiveness of superconductive particles in plastics

International Nuclear Information System (INIS)

Pienkowski, T.; Kincaid, J.; Lanagan, M.T.; Poeppel, R.B.; Dusek, J.T.; Shi, D.; Goretta, K.C.

1988-09-01

The ability to cool superconductors with liquid nitrogen instead of liquid helium has opened the door to a wide range of research. The well known Meissner effect, which states superconductors are perfectly diamagnetic, suggests shielding applications. One of the drawbacks to the new ceramic superconductors is the brittleness of the finished material. Because of this drawback, any application which required flexibility (e.g., wire and cable) would be impractical. Therefore, this paper presents the results of a preliminary investigation into the shielding effectiveness of YBa 2 Cu 3 O/sub 7-x/ both as a composite and as a monolithic material. Shielding effectiveness was measured using two separate test methods. One tested the magnetic (near field) shielding, and the other tested the electromagnetic (far field) shielding. No shielding was seen in the near field measurements on the composite samples, and only one heavily loaded sample showed some shielding in the far field. The monolithic samples showed a large amount of magnetic shielding. 5 refs., 5 figs

Shielding and grounding in large detectors

International Nuclear Information System (INIS)

Radeka, V.

1998-09-01

Prevention of electromagnetic interference (EMI), or ''noise pickup,'' is an important design aspect in large detectors in accelerator environments. Shielding effectiveness as a function of shield thickness and conductivity vs the type and frequency of the interference field is described. Noise induced in transmission lines by ground loop driven currents in the shield is evaluated and the importance of low shield resistance is emphasized. Some measures for prevention of ground loops and isolation of detector-readout systems are discussed

Tax Shield, Insolvenz und Zinsschranke

OpenAIRE

Arnold, Sven; Lahmann, Alexander; Schwetzler, Bernhard

2010-01-01

Dieser Beitrag analysiert den Wertbeitrag fremdfinanzierungsbedingter Steuervorteile (Tax Shield) unter realistischen Bedingungen (keine Negativsteuer; mögliche Insolvenz) für unterschiedliche Finanzierungspolitiken. Zusätzlich wird der Effekt der sogenannten Zinsschranke auf den Wert des Tax Shield ermittelt. Die Bewertung des Tax Shield mit und ohne Zinsschranke findet im einperiodigen Fall auf der Basis von Optionspreismodellen und im mehrperiodigen Fall auf der Basis von Monte Carlo Simul...

Measuring space radiation shielding effectiveness

OpenAIRE

Bahadori Amir; Semones Edward; Ewert Michael; Broyan James; Walker Steven

2017-01-01

Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles ...

Investigation of ionizing radiation shielding effectiveness of decorative building materials used in Bangladeshi dwellings

Science.gov (United States)

Yesmin, Sabina; Sonker Barua, Bijoy; Uddin Khandaker, Mayeen; Tareque Chowdhury, Mohammed; Kamal, Masud; Rashid, M. A.; Miah, M. M. H.; Bradley, D. A.

2017-11-01

Following the rapid growing per capita income, a major portion of Bangladeshi dwellers is upgrading their non-brick houses by rod-cement-concrete materials and simultaneously curious to decorate the houses using luxurious marble stones. Present study was undertaken to investigate the gamma-ray attenuation co-efficient of decorative marble materials leading to their suitability as shielding of ionizing radiation. A number of commercial grades decorative marble stones were collected from home and abroad following their large-scale uses. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the mass attenuation coefficients of the studied materials for high energy photons. Some allied parameters such as half-value layer and radiation protection efficacy of the investigated marbles were calculated. The results showed that among the studied samples, the marble 'Carrara' imported from Italy is suitable to be used as radiation shielding material.

Gonad shielding in computerized tomography

International Nuclear Information System (INIS)

Rockstroh, G.

1984-01-01

The reduction of gonadal dose by shielding of the gonads was investigated for a Somatom 2 using an anthropomorphic phantom. For small distances from the slice examined the gonadal dose results from intracorporal secondary radiation and is only insignificantly reduced by shielding. For greater distances shielding is relatively more effective, the gonadal dose however is small because of the approximately exponential decay. Shielding of the gonads therefore does not seem adequate for the reduction of gonadal dose. From dose measurements in cylinder phantoms of several diameters it appears that no different results would be obtained for children and young adults. An effective reduction of gonadal dose is only possible with lead capsules for males. (author)

Radiation-resistant composite for biological shield of personnel

Science.gov (United States)

Barabash, D. E.; Barabash, A. D.; Potapov, Yu B.; Panfilov, D. V.; Perekalskiy, O. E.

2017-10-01

This article presents the results of theoretical and practical justification for the use of polymer concrete based on nonisocyanate polyurethanes in biological shield structures. We have identified the impact of ratio: polymer - radiation-resistant filling compound on the durability and protection properties of polymer concrete. The article expounds regression dependence of the change of basic properties of the aforementioned polymer concrete on the absorbed radiation dose rate. Synergy effect in attenuation of radioactivity release in case of conjoint use of hydrogenous polymer base and radiation-resistant powder is also addressed herein.

Effect of bedside shielding on air-kerma rates around gynecologic intracavitary brachytherapy patients containing 226Ra or 137Cs

International Nuclear Information System (INIS)

Papin, P.J.; Ramsey, M.J.; LaFontaine, R.L.; LePage, R.P.

1990-01-01

An anthropomorphic phantom was implanted with 226Ra or 137Cs gynecologic intracavitary brachytherapy sources. Air-kerma rate measurements were taken at 10-cm increments along a horizontal plane from the side of the bed at 50 cm, 87 cm, and 136 cm heights above the floor. Five portable lead shields were placed at the head, at the foot and along one side of the bed and readings were taken again at the corresponding heights above, below and behind the shields. The readings were normalized to 100-mg Ra equivalence, and air-kerma rate curves were drawn allowing for the comparison of 226Ra and 137Cs with and without lead shields. The data demonstrated that the air-kerma rates for 137Cs were reduced more than those for 226Ra with the use of the portable lead shields. There was four times the transmission with 226Ra than with 137Cs. The optimal placement was with the lateral bedside shields proximal to the head and foot closest to the bed, with the middle shield overlapping in back. The shields at the head and foot should extend out and overlap the bedside shields. The level of the sources should be positioned near the bottom of the shields. This information will provide the medical health physicist with an estimate of air-kerma rates for both 226Ra and 137Cs with and without shielding for evaluating personnel exposures as well as the effectiveness of current shielding in relation to radiation protection requirements in adjacent rooms or hallways

Survivor shielding. Part A. Nagasaki factory worker shielding

International Nuclear Information System (INIS)

Santoro, Robert T.; Barnes, John M.; Azmy, Yousry Y.; Kerr, George D.; Egbert, Stephen D.; Cullings, Harry M.

2005-01-01

Recent investigations based on conventional chromosome aberration data by the RERF suggest that the DS86 doses received by many Nagasaki factory workers may have been overestimated by as much as 40% relative to those for other survivors in Japanese-type houses and other shielding configurations (Kodama et al. 2001). Since the factory workers represent about 25% of the Nagasaki survivors with DS86 doses in excess of 0.5 Gy (50 rad), systematic errors in their dose estimates can have a major impact on the risk coefficients from RERF studies. The factory worker doses may have been overestimated for a number of reasons. The calculation techniques, including the factory building modeling, weapon source spectra and cross-section data used in the DS86 shielding calculations were not detailed enough to replicate actual conditions. The models used did not take into account local shielding provided by machinery, tools, and the internal structure in the buildings. In addition, changes in the disposition of shielding following collapse of the building by the blast wave were not considered. The location of large factory complexes may be uncertain, causing large numbers of factory survivors, correctly located relative to each other, to be uniformly too close to the hypocenter. Any or all of these reasons are sufficient to result in an overestimate of the factory worker doses. During the DS02 studies, factory worker doses have been reassessed by more carefully modeling the factory buildings, incorporating improved radiation transport methods and cross-section data and using the most recent bomb leakage spectra (Chapter 2). Two-dimensional discrete ordinates calculations were carried out initially to estimate the effects of workbenches and tools on worker doses to determine if the inclusion of these components would, in fact, reduce the dose by amounts consistent with the RERF observations (Kodama et al. 2001). (author)

Dosimetry and shielding

International Nuclear Information System (INIS)

Farinelli, U.

1977-01-01

Today, reactor dosimetry and shielding have wide areas of overlap as concerns both problems and methods. Increased interchange of results and know-how would benefit both. The areas of common interest include calculational methods, sensitivity studies, theoretical and experimental benchmarks, cross sections and other nuclear data, multigroup libraries and procedures for their adjustment, experimental techniques and damage functions. This paper reviews the state-of-the-art and the latest development in each of these areas as far as shielding is concerned, and suggests a number of interactions that could be profitable for reactor dosimetry. Among them, re-evaluation of the potentialities of calculational methods (in view of the recent developments) in predicting radiation environments of interest; the application of sensitivity analysis to dosimetry problems; a common effort in the field of theoretical benchmarks; the use of the shielding one-material propagation experiments as reference spectra for detector cross sections; common standardization of the detector nuclear data used in both fields; the setting up of a common (or compatible) multigroup structure and library applicable to shielding, dosimetry and core physics; the exchange of information and experience in the fields of cross section errors, correlations and adjustment; and the intercomparison of experimental techniques

Evaluation of the effectiveness of the lead aprons and thyroid shields worn by cardiologists in angiography departments of two main general hospitals in Mashhad, Iran

International Nuclear Information System (INIS)

Bahreyni Toossi, M.T.; Zare, H.; Bayani, Sh.; Esmaili, S.

2008-01-01

In recent years coronary artery angiography and angioplasty procedures have become very popular. Consequently radiation protection of the cardiologists, their assistants and technicians working in the vicinity of the x-ray tube is essential. Although in recent years in developed countries, high dose x-ray examinations such as coronary angiography have attracted the attention of health physicists but in developing countries it may take some years before it would receive any attention. In Iran generally film badge is the most common personal radiation monitoring device used for this purpose; it is placed beneath the lead apron. The shielding effect of different lead aprons and thyroid shields have been evaluated. TL dosimeters, suitably calibrated, were placed over and under lead shields corresponding to the thyroid and gonad positions of the personnel. 223 angiography examinations by femoral route were included in this work. Four types of aprons and three types of thyroid shields were examined. They were different in shape and lead equivalent thickness. Our results have revealed that apron with 0.35 mmPb, one piece and front closed has maximum shielding effect. Also thyroid shield with 0.5 mmPb and very large edge provide a better protection against radiation than other types. (author)

Special radiation protection aspects of medical accelerators

CERN Document Server

Silari, Marco

2001-01-01

Radiation protection aspects relevant to medical accelerators are discussed. An overview is first given of general safety requirements. Next. shielding and labyrinth design are discussed in some detail for the various types of accelerators, devoting more attention to hadron machines as they are far less conventional than electron linear accelerators. Some specific aspects related to patient protection are also addressed. Finally, induced radioactivity in accelerator components and shielding walls is briefly discussed. Three classes of machines are considered: (1) medical electron linacs for 'conventional' radiation therapy. (2) low energy cyclotrons for production of radionuclides mainly for medical diagnostics and (3) medium energy cyclotrons and synchrotrons for advanced radiation therapy with protons or light ion beams (hadron therapy). (51 refs).

In-Plane Shielding for CT: Effect of Off-Centering, Automatic Exposure Control and Shield-to-Surface Distance

Energy Technology Data Exchange (ETDEWEB)

Kalra, Mannudeep K.; Dang, Pragya; Singh, Sarabjeet; Saini, Sanjay; Shepard, Jo Anne O. [Massachusetts General Hospital, Boston (United States)

2009-04-15

To assess effects of off-centering, automatic exposure control, and padding on attenuation values, noise, and radiation dose when using in-plane bismuth-based shields for CT scanning. A 30 cm anthropomorphic chest phantom was scanned on a 64-multidetector CT, with the center of the phantom aligned to the gantry isocenter. Scanning was repeated after placing a bismuth breast shield on the anterior surface with no gap and with 1, 2, and 6 cm of padding between the shield and the phantom surface. The 'shielded' phantom was also scanned with combined modulation and off-centering of the phantom at 2 cm, 4 cm and 6 cm below the gantry isocenter. CT numbers, noise, and surface radiation dose were measured. The data were analyzed using an analysis of variance. The in-plane shield was not associated with any significant increment for the surface dose or CT dose index volume, which was achieved by comparing the radiation dose measured by combined modulation technique to the fixed mAs (p > 0.05). Irrespective of the gap or the surface CT numbers, surface noise increased to a larger extent compared to Hounsfield unit (HU) (0-6 cm, 26-55%) and noise (0-6 cm, 30-40%) in the center. With off-centering, in-plane shielding devices are associated with less dose savings, although dose reduction was still higher than in the absence of shielding (0 cm off-center, 90% dose reduction; 2 cm, 61%) (p < 0.0001). Streak artifacts were noted at 0 cm and 1 cm gaps but not at 2 cm and 6 cm gaps of shielding to the surface distances. In-plane shields are associated with greater image noise, artificially increased attenuation values, and streak artifacts. However, shields reduce radiation dose regardless of the extent of off-centering. Automatic exposure control did not increase radiation dose when using a shield.

Structural analysis of the Passive Magnetic Shield for the ITER Heating Neutral Beam Injector system

Energy Technology Data Exchange (ETDEWEB)

Cabrera, Santiago, E-mail: santiago.cabrera@ciemat.es [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); Rincón, Esther; Ahedo, Begoña; Alonso, Javier; Barrera, Germán; Ramos, Francisco; Ríos, Luis [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); El-Ouazzani, Anass; García, Pablo [ITER Organization, Route de Vinon-sur-Verdon – CS 90 046, 13067 St Paul Lez Durance Cedex (France); Agarici, Gilbert [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3 – 07/08, 08019 Barcelona (Spain)

2015-10-15

The ITER Passive Magnetic Shield (PMS) main function is to protect the Neutral Beam Injector (NBI) from the external magnetic field coming from the tokamak, and to shield the NB cell from the radiation coming from all activated components. The shielding from the external magnetic field is performed in association with the Active Compensation Cooled Correction Coils (ACCC). The Bushing and Transmission Line (TL) PMS also provides structural support for HV bushing, allowing its maintenance and providing air sealing function between NBI cell and High Voltage deck room. The paper summarizes the structural analyses performed in order to evaluate the mechanical behaviour of the HNB PMS under operation combined with seismic event. The RCC-MR Code is used to validate the design, assuming creep is negligible, since the structure is expected to be at room temperature. P-type damage is assessed.

Situations of potential exposure in self-shielding electron accelerators

International Nuclear Information System (INIS)

Rios, D.A.S.; Rios, P.B.; Sordi, G.M.A.A.; Carneiro, J.C.G.G.

2017-01-01

The study discusses situations in the industrial environment that may lead to potential exposure of Occupationally Exposed Individuals and Public Individuals in self-shielding electron accelerators. Although these exposure situations are unlikely, simulation exercises can lead to improvements in the operating procedure as well as suggest changes in production line design in order to increase radiation protection at work. These studies can also be used in training and demonstrate a solid application of the ALARA principle in the daily activities of radiative installations

Nuclear analysis and shielding optimisation in support of the ITER In-Vessel Viewing System design

International Nuclear Information System (INIS)

Turner, Andrew; Pampin, Raul; Loughlin, M.J.; Ghani, Zamir; Hurst, Gemma; Lo Bue, Alessandro; Mangham, Samuel; Puiu, Adrian; Zheng, Shanliang

2014-01-01

The In-Vessel Viewing System (IVVS) units proposed for ITER are deployed to perform in-vessel examination. During plasma operations, the IVVS is located beyond the vacuum vessel, with shielding blocks envisaged to protect components from neutron damage and reduce shutdown dose rate (SDR) levels. Analyses were conducted to determine the effectiveness of several shielding configurations. The neutron response of the system was assessed using global variance reduction techniques and a surface source, and shutdown dose rate calculations were undertaken using MCR2S. Unshielded, the absorbed dose to piezoelectric motors (PZT) was found to be below stable limits, however activation of the primary closure plate (PCP) was prohibitively high. A scenario with shielding blocks at probe level showed significantly reduced PCP contact dose rate, however still marginally exceeded port cell requirements. The addition of shielding blocks at the bioshield plug demonstrated PCP contact dose rates below project requirements. SDR levels in contact with the isolated IVVS cartridge were found to marginally exceed the hands-on maintenance limit. For engineering feasibility, shielding blocks at bioshield level are to be avoided, however the port cell SDR field requires further consideration. In addition, alternative low-activation steels are being considered for the IVVS cartridge

Nuclear analysis and shielding optimisation in support of the ITER In-Vessel Viewing System design

Energy Technology Data Exchange (ETDEWEB)

Turner, Andrew, E-mail: andrew.turner@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Pampin, Raul [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Loughlin, M.J. [ITER Organisation, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Ghani, Zamir; Hurst, Gemma [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Lo Bue, Alessandro [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Mangham, Samuel [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Puiu, Adrian [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Zheng, Shanliang [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2014-10-15

The In-Vessel Viewing System (IVVS) units proposed for ITER are deployed to perform in-vessel examination. During plasma operations, the IVVS is located beyond the vacuum vessel, with shielding blocks envisaged to protect components from neutron damage and reduce shutdown dose rate (SDR) levels. Analyses were conducted to determine the effectiveness of several shielding configurations. The neutron response of the system was assessed using global variance reduction techniques and a surface source, and shutdown dose rate calculations were undertaken using MCR2S. Unshielded, the absorbed dose to piezoelectric motors (PZT) was found to be below stable limits, however activation of the primary closure plate (PCP) was prohibitively high. A scenario with shielding blocks at probe level showed significantly reduced PCP contact dose rate, however still marginally exceeded port cell requirements. The addition of shielding blocks at the bioshield plug demonstrated PCP contact dose rates below project requirements. SDR levels in contact with the isolated IVVS cartridge were found to marginally exceed the hands-on maintenance limit. For engineering feasibility, shielding blocks at bioshield level are to be avoided, however the port cell SDR field requires further consideration. In addition, alternative low-activation steels are being considered for the IVVS cartridge.

Improving the shielding effectiveness of a board-level shield by bonding it with the waveguide-below-cutoff principle

OpenAIRE

Degraeve, Andy; Pissoort, Davy; Armstrong, Keith

2015-01-01

This paper discusses the shielding performance or shielding effectiveness of a board-level shield in function of its bonding method. Improved shielding performance at board-level in order to harden integrated circuits against unintentional and intentional electromagnetic interference, and this under harsh environmental conditions, is getting more and more important to achieve the desired levels of functional performance and operational reliability despite an ever more aggressive electromagnet...

Antithermal shield for rockets with heat evacuation by infrared radiation reflection

Directory of Open Access Journals (Sweden)

Ioan RUSU

2010-12-01

Full Text Available At high speed, the friction between the air mass and the rocket surface causes a localheating of over 1000 Celsius degrees. For the heat protection of the rocket, on its outside surfacethermal shields are installed.Studying the Coanda effect, the fluid flow on solids surface, respectively, the author Ioan Rusuhas discovered by simply researches that the Coanda effect could be /extended also to the fluid flowon discontinuous solids, namely, on solids provided with orifices. This phenomenon was named by theauthor, the expanded Coanda effect. Starting with this discovery, the author has invented a thermalshield, registered at The State Office for inventions and Trademarks OSIM, deposit F 2010 0153This thermal shield:- is built as a covering rocket sheet with many orifices installed with a minimum space fromthe rocket body- takes over the heat fluid generated by the frontal part of the rocket and avoids the directcontact between the heat fluid and the rocket body- ensures the evacuation of the infrared radiation, generated by the heat fluid flowing overthe shield because of the extended Coanda effect by reflection from the rocket bodysurface.

Optimal Magnetic Field Shielding Method by Metallic Sheets in Wireless Power Transfer System

Directory of Open Access Journals (Sweden)

Feng Wen

2016-09-01

Full Text Available To meet the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs such as the International Committee on Non-Ionizing Radiation Protection (ICNIRP guidelines, thin metallic sheets are often used to shield magnetic field leakage in high power applications of wireless power transfer (WPT systems based on magnetic field coupling. However, the metals in the vicinity of the WPT coils cause the decrease of self and mutual inductances and increase of effective series resistance; as such, the electric performance including transmission power and the efficiency of the system is affected. With the research objective of further investigating excellent shielding effectiveness associated with system performance, the utilization of the optimal magnetic field shielding method by metallic sheets in magnetic field coupling WPT is carried out in this paper. The circuit and 3D Finite Element Analysis (FEA models are combined to predict the magnetic field distribution and electrical performance. Simulation and experiment results show that the method is very effective by obtaining the largest possible coupling coefficient of the WPT coils within the allowable range and then reducing the value nearest to and no smaller than the critical coupling coefficient via geometric unbroken metallic sheets. The optimal magnetic field shielding method which considers the system efficiency, transmission power, transmission distance, and system size is also achieved using the analytic hierarchy process (AHP. The results can benefit WPT by helping to achieve efficient energy transfer and safe use in metal shielded equipment.

Shielding design of ITER pressure suppression system

International Nuclear Information System (INIS)

Yamauchi, Michinori; Sato, Satoshi; Nishitani, Takeo; Kawasaki, Hiromitsu

2006-01-01

The duct shield from streaming D-T neutrons has been designed for the ITER pressure suppression system. Streaming calculations are performed with the DUCT-III code for the region from the inlet of the pressure relief line to the rupture disk. Next, the neutron permeation through the shield is studied by Monte Carlo calculations with the MCNP code. It is found that 0.15 m thick iron shield is enough to suppress the permeating component from the outside. In addition, it is suggested that the volume of the shield can be reduced by about 30% if the optimized iron shield structure having localized thickness across intense permeation paths is employed to shield the pressure suppression line. (T.I.)

Spectral perturbations from silicon diode detector encapsulation and shielding in photon fields.

Science.gov (United States)

Eklund, Karin; Ahnesjö, Anders

2010-11-01

Silicon diodes are widely used as detectors for relative dose measurements in radiotherapy. The common manufacturing practice is to encapsulate the diodes in plastic for protection and to facilitate mounting in scanning devices. Diodes intended for use in photon fields commonly also have a shield of a high atomic number material (usually tungsten) integrated into the encapsulation to selectively absorb low-energy photons to which silicon diodes would otherwise over-response. However, new response models based on cavity theories and spectra calculations have been proposed for direct correction of the readout from unshielded (e.g., "electron") diodes used in photon fields. This raises the question whether it is correct to assume that the spectrum in a water phantom at the location of the detector cavity is not perturbed by the detector encapsulation materials. The aim of this work is to investigate the spectral effects of typical encapsulations, including shielding, used for clinical diodes. The effects of detector encapsulation of an unshielded and a shielded commercial diode on the spectra at the detector cavity location are studied through Monte Carlo simulations with PENELOPE-2005. Variance reduction based on correlated sampling is applied to reduce the CPU time needed for the simulations. The use of correlated sampling is found to be efficient and to not introduce any significant bias to the results. Compared to reference spectra calculated in water, the encapsulation for an unshielded diode is demonstrated to not perturb the spectrum, while a tungsten shielded diode caused not only the desired decrease in low-energy scattered photons but also a large increase of the primary electron fluence. Measurements with a shielded diode in a 6 MV photon beam proved that the shielding does not completely remove the field-size dependence of the detector response caused by the over-response from low-energy photons. Response factors of a properly corrected unshielded diode

Superconducting magnetic shields production. Realisation d'ecrans magnetiques supraconducteurs

Energy Technology Data Exchange (ETDEWEB)

Lainee, F; Kormann, R [Thomson-CSF, Domaine de Corbeville, 91 - Orsay (FR); Lainee, F [Ecole des Mines de Paris, 91 - Evry (FR)

1992-02-01

Low fields and low frequency shielding properties of YBCO magnetic shields are measured at 77 K. They compare favourably with shielding properties of mumetal shields. Therefore high-T{sub c} superconducting magnetic shields can already be used to shield small volumes. The case of magnetic shields for large volumes is also discussed. 3 refs; 6 figs; 4 tabs.

Problems of the power plant shield optimization

International Nuclear Information System (INIS)

Abagyan, A.A.; Dubinin, A.A.; Zhuravlev, V.I.; Kurachenko, Yu.A.; Petrov, Eh.E.

1981-01-01

General approaches to the solution of problems on the nuclear power plant radiation shield optimization are considered. The requirements to the shield parameters are formulated in a form of restrictions on a number of functionals, determined by the solution of γ quantum and neutron transport equations or dimensional and weight characteristics of shield components. Functional determined by weight-dimensional parameters (shield cost, mass and thickness) and functionals, determined by radiation fields (equivalent dose rate, produced by neutrons and γ quanta, activation functional, radiation functional, heat flux, integral heat flux in a particular part of the shield volume, total energy flux through a particular shield surface are considered. The following methods of numerical solution of simplified optimization problems are discussed: semiempirical methods using radiation transport physical leaks, numerical solution of approximate transport equations, numerical solution of transport equations for the simplest configurations making possible to decrease essentially a number of variables in the problem. The conclusion is drawn that the attained level of investigations on the problem of nuclear power plant shield optimization gives the possibility to pass on at present to the solution of problems with a more detailed account of the real shield operating conditions (shield temperature field account, its strength and other characteristics) [ru

Neutron shielding for a 252 Cf source

International Nuclear Information System (INIS)

Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Eduardo Gallego, Alfredo Lorente

2006-01-01

To determine the neutron shielding features of water-extended polyester a Monte Carlo study was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through inelastic collisions and absorption reactions. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide production induced by neutron activation must be considered. In this investigation the Monte Carlo method was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a 252 Cf isotopic neutron source. During calculations a detailed model for the 252 Cf and the shield was utilized. To compare the shielding features of water extended polyester, the calculations were also made for the bare 252 Cf in vacuum, air and the shield filled with water. For all cases the calculated neutron spectra was utilized to determine the ambient equivalent neutron dose at four sites around the shielding. In the case of water extended polyester and water shielding the calculations were extended to include the prompt gamma rays produced during neutron interactions, with this information the Kerma in air was calculated at the same locations where the ambient equivalent neutron dose was determined. (Author)

Meeting the Grand Challenge of Protecting Astronaut's Health: Electrostatic Active Space Radiation Shielding for Deep Space Missions

Data.gov (United States)

National Aeronautics and Space Administration — This study will seek to test and validate an electrostatic gossamer structure to provide radiation shielding. It will provide guidelines for energy requirements,...

Influence of bismuth shielding use in the dose CT and the imaging quality in standard brain protocol

International Nuclear Information System (INIS)