Sealed Sources Research Articles

Potential for Contamination during Removal of Radioactive Seeds from Surgically Excised Tissue

The purpose of this study was to determine whether the use of a scalpel or electrocautery to remove radioactive sealed sources ("seeds") from surgically excised tissue could damage the seed and cause it to leak its radioactive contents. Attempts were made to cut or burn Oncura Model 6711 non-radioactive seeds while in pig muscle or on a stainless steel plate. Additionally, one active 125I seed was purposely charred using pressure with an electrocautery knife to see whether the casing could be damaged. Electron microscopy scanning was performed on the dummy seeds to determine if the integrity of the metal casing had been compromised. Two types of leak tests were performed on the active seed to verify the presence or absence of loose contamination. The seed casing was not damaged from either use of a scalpel or electrocautery when the seed was in tissue. The active seed was not found to be leaking after applying pressure with an electrocautery knife while the seed was on a stainless steel plate. We conclude that removal of active Model 6711 seeds from surgically excised tissue can be done safely with a scalpel or electrocautery because constant, firm pressure cannot be applied to the seed. This is likely true for seeds made of similar materials.

“Age” determination of irradiated materials utilizing inductively coupled plasma mass spectrometric (ICP-MS) detection

A gas pressurized extraction chromatography (GPEC) system has been developed to perform elemental separations on radioactive samples to determine total and isotopic compositions of Cs and Ba from an irradiated salt sample, fuel sample and two sealed radiation sources. The GPEC system employs compressed nitrogen to move liquid through the system, compared to gravity or pumped liquids that are typically used for separations. A commercially available Sr-Resin™ was used to perform the separation for the above mentioned analytes. A 1% acetic acid solution was determined to be the best extractant for Ba. A flow rate of 0.1 mL/min was determined to be optimal for the separation of Ba. Complete recovery of the Cs and Ba was achieved, within the systematic uncertainties of the experiments.

TU-D-211A-01: U.S. NRC Regulatory Initiatives in Enhancing Accountability of Radioactive Material

As the lead U.S. regulatory agency for civilian uses of radioactive material, the United States Nuclear Regulatory Commission (USNRC) plays a key role in domestic and international security activities. The events of September 11, 2001 highlighted the need to enhance security to address potential terrorist threats. The USNRC took numerous immediate actions to enhance materials security and also initiated broader programs, designed to improve security in a comprehensive manner over the long‐term. As with its other regulatory programs, USNRC utilized a risk‐informed, graded approach to enhance security. Consistent with the risk‐informed approach, it was necessary to categorize radioactive sources and materials according to risk. USNRC cooperated with other domestic organizations and the International Atomic Energy Agency (IAEA) in revising and adopting the security principles and source categories in the IAEA Code of Conduct. The highest risk sources were designated as Category 1 and 2. Based on these categories, USNRC then developed and issued enhanced security requirements to the U.S. licensees who possess Category 1 and 2 radioactive sources. In parallel with these efforts, USNRC worked with other organizations to improve the overall nuclear security infrastructure. The U.S. Congress passed the Energy Policy Act of 2005, which created the Radiation Source Security and Protection Task Force. This Task Force is chaired by USNRC and is composed of representatives from 13 Federal agencies and 2 States. It is a primary vehicle for advancing source security issues across the U.S. government. This presentation describes an important element of the security infrastructure, the National SourceTracking System (NSTS). The system was launched in late 2008 after several years of development. The NSTS maintains an inventory of all Category 1 and 2 sources in the U.S. Licensees are required to maintain their inventory data and report transfers online. This enhances security by allowing close tracking of the locations of sources, and identifying possible unauthorized transfers. For the future, USNRC plans to integrate the NSTS into a broader electronic license verification system so that questions about sources and license authorization can be quickly resolved. This presentation will focus on the following topics regarding tracking Category 1 and 2 sealed sources with the National SourceTracking System: 1. Deployment and Implementation of NSTS 2. Experience with NSTS 3. Credentialing Process for Access to NSTS 4. Potential Expansion of the System 5. User Feedback 6. Questions

Quality assurance management system for spent radioactive sealed sources in Egypt

AbstractTo achieve the overall protection goals set by the regulatory authorities, Quality Assurance (QA) has to take place in every phase of a waste management system. It is the duty of the Hot Laboratories Center (HLC), to develop a quality system starting from the Quality Assurance Management System (QAMS) for all activities concerned with the management and safety of radioactive waste to be confident that the work will be accomplished according to written and approved procedures to protect the public, employees and the environment from any mismanagement of radioactive waste. It is intended that this QAMS document is closely integrated with system planning. As work scope is adjusted to reflect schedule adjustments, resource limitations, or other scope changes due to programmatic considerations, changes or revisions of QA requirements that result will be accomplished by revisions of this QAMS and its subordinate quality plans. The Quality Assurance Program (QAP) is described in planning documents and implementing procedures that contain detailed instructions for each process or activity. The QAP serves as a resource for the technical staff to ensure that the results of the compliance assessment are traceable and reproducible, that accountability is maintained, and that conclusions are based on sound practices. Copyright © 2009 John Wiley & Sons, Ltd.

Quality assurance program for spent radioactive sealed sources in Egypt

AbstractEffective implementation of the Hot Laboratories Center Quality Assurance Program (QAP) is dependent on the efforts at all levels of all participants. Management is responsible for defining quality, developing appropriate plans to attain quality, and supporting the workers in the pursuit of quality. QA organizations of the program participants are responsible for verifying the achievement of quality in the implementation of the Hot Laboratories Center QA program. A written QAP shall be developed, implemented, and maintained. The QAP describes the organizational structure, functional responsibilities, levels of authority, and interfaces for those managing, performing, and assessing the work. The QAP shall describe the management processes, including planning, scheduling, and resource considerations. The organization, responsibilities/authorities of all participants, internal and external interfaces, and lines of communication should be established during the conceptual phase. Quality Assurance (QA) as an essential management tool is being strongly applied in the area of predisposal of Spent Radioactive Sealed Sources (SRSS). Quality Control is now considered as part of the planning and systematic actions of QA. To ensure compliance with the requirements, and to assure the envisaged behavior of the SRSS package and disposal system, a QAP for all stages of SRSS management, including SRSS conditioning, transportation, storage, and disposal are required. Copyright © 2009 John Wiley & Sons, Ltd.

Recovery and purification of 4.66 TBq(126 Ci) of 137Cs from a 20-year-old spent sealed source

An attempt to recover and purify 4.66 TBq(126 Ci) of 137Cs as solution from a 20-year-old doubly encapsulated sealed source containing 137CsCl was made successfully. The primary capsule was first cut open to retrieve the secondary capsule. The top end of the secondary SS capsule was then cut to render it as an open cylinder and the 137CsCl pellet inside was dissolved in small aliquots of water. Each aliquot of the 137CsCl solution was dispensed into glass vials, sealed, assayed and stored. Barium formed during the radioactive decay of 137Cs was removed by carbonate precipitation. Chloride was removed by heating with HNO 3 and evaporation. About 91.8% of the total activity could be recovered and used subsequently for making brachytherapy sources.

Total Occupational Exposure During Characterisation, Conditioning, and Securing of Radioactive Sealed Sources: A New Dosimetric Concept Using Active Electronic Dosimeters

Radiation dosimetry in protection against ionising radiation involves research of all possible pathways through which natural or man-made radioactive materials can contaminate a habitat and actually harm its biota. It also takes into account natural and artificial (man-made) electromagnetic ionizing radiation (gamma and x radiation). This article presents a dosimetric study assessing exposure to man-made ionising radiation of local environment and total occupational exposure of two professional workers involved in characterisation, conditioning, and securing of unused radioactive sealed sources. The purpose of the study was to validate a new active electronic dosimeter (AED) of type ALARA OD and to develop a new monitoring method by tracing the external occupational exposure over real time. This method is used to continuously measure and record external radiation doses and, which is a novelty, establish dose rates receiving pattern as a function of real time. Occupational whole body dosimetric results obtained with AED were compared with results obtained with passive dosimetry (film badge and thermoluminiscence). Air, dust, and silicon sand samples were analysed by gamma-spectrometry to estimate internal exposure of the two workers to 222Rn due to inhalation or ingestion of dust and sand in indoor air. In order to establish total occupational exposure, control radon measurement was performed in the immediate environment and the external Hazard index (Hex) was calculated.

Ir-192 방사선원의 밀봉 용접부 품질에 미치는 저항용접 공정변수의 영향

Ir-192 radiation sealed sources are widely employed to the therapeutic applications as well as the non-destructive testing. Production of Ir-192 sources requires a delicate but robust welding technique because it is employed in a high radioactive working environment. A GTA(Gas Tungsten Arc) welding technique is currently well established for this purpose. However, this welding method requires a frequent replacement of the electrode, which results in the delay of the production to take a preparatory action such as to isolate the radiation sources from the working place before getting access to the welding machine. Hence, a resistance welding technique is considered as an alternative method of the GTA welding technique. The advantages of resistance welding are high welding speed and high-rate production. Also it has very long life of electrode comparing to GTA welding. In this study, the resistance welding system and proper welding conditions were established for sealing Ir-192 source capsule. As a results of various experiments, it showed that electrode displacement can be employed as a indicator to predict welding quality. We proposed two mathematical models(linear and curvilinear) to estimate electrode displacement with process parameters such as applied force, welding current and welding time by using regression analysis method. Predicting results of both linear and curvilinear model were relatively good agreement with experiment.

Flow-rate measurements of a dual-phase pipe flow by cross-correlation technique of transmitted radiation signals

The flow rate measurements of dual-phase pipe flow were conducted with a couple of sealed radioisotopes for the cross-correlation technology. The flow was produced in an acrylic tubing of which internal diameter is 8 cm and into which pressurized nitrogen gas was periodically injected. Under the given conditions where the distance between two sources is four times of the diameter, N/ S ratio ranges from 0.12 to 0.15 and the data sampling time is 4 ms, the measured flow rates were estimated with the maximum relative error of 1.7%. From the subsequent experiments, it was proven that the closer the distance between the two sealed sources is, the higher the precision of measurement result is. It is anticipated that the industrial application of the technique for flow rate measurements in an in-service process can play an important role for monitoring multi-phase process media in petrochemical and refinery industries.

Combination of sealed source and radiotracer technique to understand malfunctioning in a chemical plant

Pure terphthalic acid (PTA) is produced by the oxidation of paraxylene in an oxidation reactor of a PTA plant. Since the reaction is exothermic, the temperature rises above 210 °C. Vapours formed in the reactor are passed through a series of heat exchangers and the cooled liquid is fed back to the reactor, which flows to the reactor by gravity. In one of the heat exchangers, improper flow distribution in the inlet and outlet pipelines was suspected. Maldistribution of flow in the heat exchanger was also suspected. Gamma scanning of the pipelines and a radiotracer experiment were carried out in the heat exchanger to study the malfunctioning. A specially fabricated pipe scanner was used to scan both 24 in diameter and 16 in diameter pipelines. From gamma scanning of the pipelines mostly on the bends, absence of the full bore flow of the liquid was observed. Presence of vapours along with the liquid could be obstructing the liquid flow, thereby causing the malfunctioning. A radiotracer experiment was also carried out to study the flow pattern in the heat exchanger. From the experiment, mean residence time of the heat exchanger was estimated as 470 s, which theoretically should be about 102 s. It indicated that the flow is decelerated in the heat exchanger because of the presence of vapour lock in the tube side.

Preparation of 65Zn and 134Cs sealed sources based on commercial organic and synthesized inorganic sorbents for calibration purposes of γ-detectors

The sealed source of 65Zn was prepared by using permutit as a commercial organic resin in an anion form, while in case of the 134Cs, the sealed source was prepared by using the synthesized 12-molybdocerate(IV) gel as an inorganic exchanger in cation form. The batch technique was carried out for loading 65Zn from 0.2 M HCl-60% acetone medium and for loading 134Cs from 0.005 M HNO 3 onto the appropriate exchanger. The sealed source material of 65Zn-permutit or 134Cs-12-molybdocerate(IV), about 100 mg, was placed inside the cavity of a holder capsule (artelone) and its activity was measured to be 56.61±2.59 kBq (1.53±0.07 μCi) for 65Zn on 21 April 2008 and 1.48±0.089 kBq (0.04±0.0024 μCi) for 134Cs on 5 May 2008. The self absorption was calculated by using artelone and compared with the same thickness of stainless steel capsule as the holder material. The quality control was performed on the prepared sealed sources.

Wipe testing of sealed radiation sources using a radiation protection assistant robot

Sealed radiation sources are commonly used in different research institutes, industries, and hospitals. The sources of various strengths are manufactured in different sizes and shapes. It is a regulatory requirement that these sources must be monitored frequently for their integrity and to avoid any radiological contamination hazard. Mainly, a wipe test is recommended for the contamination detection due to the leakage of sealed radiation sources. A radiation protection assistant robot has been fabricated to execute different tasks in a hazardous radiation environment. In this study, the robot was used to conduct the wipe test of five sealed radiation sources. The sealed radiation sources were tested safely and securely without giving any radiation dose to the radiation worker. The radiation doses received by the robot gripper and waist during the wipe test were 3.4 Gy and 208.9 mGy, respectively.

Radioisotopes applications in industry: an overview

Radioactive isotopes, particularly in the form of radiotracers and radioactive sealed sources, have been used over a broad spectrum of process industries for equipment and process troubleshooting, monitoring, control, inspection, optimisation and many other purposes. Radioisotope-based measurement techniques are best suited for multiphase flow systems encountered in industrial processes, since these systems are opaque and contain a large volume fraction of the dispersed phase. In this manuscript, some of these techniques and their applications are outlined and discussed.

Lack of international consensus on the disposition and storage of disused sealed sources

A lower-activity analogue of the trans-national problem of spent fuel management and disposal is the global problem of radioactive sealed source [source: The IAEA definition of a sealed source is “Radioactive material that is permanently sealed in a capsule or closely bonded and in a solid form.” Taken from glossary of Nuclear Waste Data Management found at http://www-ewmdb.iaea.org/showhelp.asp?Topic=8-1-1.] disposal. Sources are found in almost every country in the world because of their beneficial medical and commercial or industrial applications. Some of the isotopes used have short half-lives—iridium-192 (Ir-192), 73.8 days—while others have very long half-lives—americium-241 (Am-241), 432 years or plutonium-239 (Pu-239), 24,130 years. It is critically important, particularly for longer-lived isotopes, to find final disposition pathways. Lack of a permanent disposition pathway such as recycling or irretrievable disposal creates numerous problems, including the potential loss of regulatory control, which increases the risk of inadvertent or deliberate misuse of the material. The misuse of radioactive materials has the potential for substantial public health and economic damage. Disused sources also pose an inherent risk to the end-users from a liability, safety, and public health perspectives. This paper examines various disposition pathways employed by several key source manufacturing or possessing nation-states for disused sources. Examples of source disposition pathways include long-term storage, deep geological disposal, borehole disposal and shallow land burial. The Off-Site Source Recovery Project (OSRP), part of the office of Global Threat Reduction Initiative (GTRI), acts as an intermediary in the recovery and ultimate disposition of US origin sealed radiological materials. Several concepts that could help mitigate the challenge of a lack of long-term disposition options for sources are available, but these tools have not yet been applied by most nation-states. For example, regional consolidation and repatriation of sources to the country of manufacture would ease or eliminate the need for in situ disposal or storage in a number of developing nation-states.

Safety during whole life time: important aspect in safety assessment of sealed radioactive sources

AbstractMany sealed sources with long halflife isotopes commonly used in industry or medicine have a long working life, up to several decades. Source integrity must be guaranteed in transport and use at any time. On the one hand, safety during the working life has to be ensured by the source design. Its strain has to be tested. On the other hand, source durability depends on the specific operating conditions. BAM as the competent authority in Germany has to assess the suitability of a source design for safe transport and use also for a longer service life for: (a) sources approved as special form radioactive material according to the regulations for the safe transport of radioactive material, (b) sources in approved devices for licence free use according to the Radiation Protection Ordinance, Para 25, and (c) sources with an extended leak test period according to Radiation Protection Ordinance, Para 66. In all these domains BAM has to assess if design and additional arrangements are qualified and guarante...

Optimizing signal-to-noise on a home X-ray source for the analysis of microcrystals

The concept of using a microfocus X-ray source in combination with X-ray optics for diffraction experiments was first pioneered by U. Arndt in the early 90’s. Since then, there have been numerous research activities for finding suitable combinations of high-brilliant microfocusing sealed tube X-ray sources and X-ray optics (e.g. capillaries, TR mirrors). A major breakthrough was the development of graded multilayer mirrors by H. Goebel. Combining graded multilayer mirrors with a state-of-the-art high-brilliance microfocus sealed tube results in a new class of high-brilliant X-ray sources for the home lab. These sources are characterized by a high performance (high flux densities, high spatial resolution) and excellent beam stability together with low power consumption and low maintenance. Third generation microfocusing sealed tube sources, such as the IμS (Incoatec Microfocus Source), are now well established and give a performance beyond that of typical traditional X-ray sources at power settings far below 1 kW. However, the past research work was focused, almost exclusively, on sources using Cu radiation. We will present selected results from single crystal diffraction experiments with the IμS for Mo radiation. The flux density obtained from this source is about 1.5 times the flux density of a 5 kW rotating anode plus graphite monochromator on a 100 μm sample. In our experiments with very small crystals (< 50 μm), we have achieved gain factors of up to 3. Our results show that this source-opticscombination is very well suited for the structure determination on small crystals, as well as on medium sized samples.

A bulk silicon micromachined structure for gas microdischarge-based detection of beta-particles

This paper describes two Si micromachined structures for sensing beta-particles. The basic device (the micro-detector) includes a square silicon cathode surrounded by a concentric anode, and is formed by stacks of glass and Si wafers. Incident beta-particles ionize the gas encapsulated between the electrodes, resulting in an avalanche current pulse or ‘count’. It is shown experimentally that devices with 8 × 8 mm2 footprint can detect radiation in the proximity of sealed sources, such as 90Sr and 204Tl with 0.1–1.0 µCi strengths. The sensitivity (cpm mRad−1 h) of the micromachined device is comparable to that of commercial radiation detectors, but substantially superior when normalized to the detector volume, which is about 0.06% of the conventional detectors. An extension of the basic device, the stacked micro-detector, consists of a two-tiered arrangement of cavities separated by a thin glass intercavity attenuator that is intended to provide controlled energy absorption. Higher energy particles are detected in both cavities, while lower energy particles are detected in the first cavity and subsequently absorbed by the intercavity attenuator. This can provide initial assessment of the incident radiation without adding significant complexity to the system. Preliminary experimental validation is performed by comparing the device response to 204Tl and 90Sr.

Transmission positron images using imaging plates

As an image recording medium for transmission positron microscopes, imaging plates are quite useful and powerful. Imaging plates are also quite sensitive and the photon-stimulated luminescence (PSL) is linearly proportional to the positron intensity in six digits (10 6). No bulky or expensive equipment is necessary to accommodate in vacuum. Imaging plates can be set under bright lights, this is different from the photographic films. Darkness is only required during exposure and transfer to a reader. Slow Positron Facility at KEK, Japan was used to study the effect of “mono-chromatic” positron beam. Specimens were set just in front of an imaging plate. After a certain time of exposure, the imaging plates were processed by a reader. Used imaging plates can be used repeatedly after erased by ultra-violet lights. Images through samples can be obtained. Similar experiments using non-monochromatic (white) positrons and electrons have been performed at Teikyo University of Science and Technology (TUST) and Research Reactor Institute, Kyoto Univ. (RRI). Sealed 22Na positron source can be conveniently used for non-destructive tests.

Fully sealed carbon nanotube flat-panel light source and its application as thin film transistor–liquid-crystal display backlight

The authors investigated a full sealed flat-panel light source, which is based on a triode structure with a metal mesh gate electrode and uses a carbon nanotube cold cathode. It has a flat surface luminance distribution with good uniformity, a stable luminance of 12000cd∕m2, and a luminous efficiency that was measured to be 14.5lm∕W. It also shows a high color rendering index of 88 and a wide optical emission spectrum. Further, its application as thin film transistor–liquid-crystal display (TFT-LCD) backlight was demonstrated and the resulted performance of the TFT-LCD display was studied and compared to the commercial TFT-LCD products, which use the cold-cathode fluorescent lamp backlight and light emitting diode backlight. It is shown that the light transmission ratio in the TFT-LCD module using our light source is ∼8%, as compared to ∼4% of the commercial products. With this and the very high luminance, our light source is very useful to the situation, in which the TFT-LCD screen is employed to work under outdoor sunshine conditions.

Mobile PET in the UK: legislative, regulatory and cost-effectiveness considerations

Mobile PET/CT or mobile stand alone PET, is becoming more widely available throughout the developed world, allowing many small and medium-sized hospitals that do not have the scale or financial resources to purchase the static diagnostic equipment, to benefit from this imaging technology. Before embarking on such a service, a number of legislative, logistical and administrative issues have to be addressed to ensure that a mobile PET/CT service is run with optimal efficiency and safety and in compliance with the regulations governing the use of radioactive substances. Some of these issues are similar to those encountered in operating a mobile magnetic resonance imaging scanner but there are important differences owing to the use of both sealed and open radioactive sources. This article highlights the legislative, administrative and practical issues relevant to the UK and also discusses some of the practical issues that need to be addressed to ensure the operation of a safe and effective PET service.