アメリシウム

Decontamination is most successful when the material can be recycled for use in a nuclear facility since the need to prove releasability (cleanliness) is eliminated. Nevertheless, cleaning material for unrestricted release is also possible in some cases. It may also be possible to decontaminate an item enough to change its classification from TRU/transuranic/ waste to LLW /low-level waste/, thereby allowing immediate disposal of the item, while a relatively small quantity of decontamination waste is stored as TRU waste. Electropolishing to remove the thinnest metal surface has been very effective and produces a relatively small waste volume, especially when one of the wetted sponge units is used rather than an emersion tank. Surface scabbling has been used in decontamination of concrete, and various abrasive blasting methods have also been effective. Strippable and self-stripping coatings may be used to decontaminate surfaces, even though the primary application of strippable coatings has been in preventing contamination of surfaces. /Plutonium facilities/

In most cases of contamination of equipment and buildings, a mixture of normal housecleaning methods will remove the material. Vacuum cleaners that can handle wet material and have high-efficiency filters are particularly useful. Some surfaces may require repeated scrubbing and vacuuming before they are free of contamination.

In most cases, contamination should be controlled, and removed as soon as possible. The contaminated area or equipment should be marked and posted immediately. Nonessential persons should be moved out of the area until decontamination has been completed. Usually simple cleaning techniques and procedures are adequate for most decontamination tasks. Spills and contaminated areas should be cleaned from the outer region inward to reduce the possibility of further spread of the contamination. After cleaning, the area or equipment should be surveyed to ensure that all the contamination has been removed.

/SRP/ Wastes in the Waste Isolation Pilot Plant (WIPP) are from the nuclear weapons industry (plutonium) - research and development. For a waste to be accepted at WIPP it must be a transuranic "TRU" waste and: (1) </= 100 nanoCi/gram, (2) an alpha emitting transuranium isotope with atomic number greater than uranium, and (3) have a half life greater than 20 years. The wastes must be handled remotely if they produce >/= 200 millirems/hr; if less, they can be contact handled.

Program design decisions can affect TRU waste-generation. For example, the quantity of protective clothing may be a significant factor. If an incinerator is available, combustible protective clothing may be selected to have a low ash content and generate a minimum of harmful effluents such as oxides of nitrogen or halogenated compounds. In other facilities, water-washable, reusable protective clothing may minimize waste disposal. /Plutonium facilities/

Another opportunity for waste minimization occurs when materials are used as a contingency protection against contamination. For example, strippable coatings may be applied to an area that is not expected to become contaminated or may receive only minor contamination so that it can be easily cleaned. Another example involves the disposition of disposable surgeons' gloves, which are routinely worn inside glove-box gloves. Unless there are serious contamination control problems in the facility, these can be surveyed and disposed of as sanitary waste rather than LLW or TRU waste. /Plutonium facilities/

Likewise, all tools and equipment to be placed in a contaminated environment should be tested for reliability and preferably used on a clean mock-up to ensure their serviceability before they become contaminated. There is often a temptation to put the equipment into ... service when it first arrives rather than test it completely first. This can result in unnecessary waste volume. /Plutonium facilities/

For more Disposal Methods (Complete) data for AMERICIUM, RADIOACTIVE (8 total), please visit the HSDB record page.

In a nuclear weapon accident involving fire or conventional explosion, most of the radiation dose received by people in the immediate vicinity would result from inhalation of plutonium-239. This is accompanied by the nuclide americium-241, which is much easier to determine by external counting because of the 60 keV gamma ray emission. In the event of an accident, a priority would be to identify any people who have had intakes of plutonium-239 which were so large that decorporation therapy should be considered. Direct measurement of lung content provides the most rapid and convenient method for assessing intakes by inhalation. A transportable system has been considered as this could be deployed close to the site of the accident and would allow rapid measurements to be made. The feasibility of a transportable americium-241-in-nose-blow and nasal swab measurement system has also been considered. This would be used to help select people for americium-241-in-lung measurements. /Americium-241 and plutonium-239)

In any facility that handles radioactive materials, the major controls protecting workers, the public, and the environment are structures and installed equipment, which shield, contain, and confine the radioactive materials. However, to allow useful work to be performed in the facility and to assure that its protective features remain effective, a number of administrative controls are ordinarily required. These administrative controls are usually contained in a series of procedures related to the operations and maintenance activities to be carried out in the facility. All personnel who work in controlled areas should be familiar with the administrative controls that apply to their work. When changes or additions to administrative controls are made, these changes or additions should be effectively communicated to all persons who may be affected. /Plutonium facilities/

Radiation Protection Procedures: A ... facility should have a written policy on radiation protection, including a policy on keeping exposures ALARA. All radiation protection procedures and controls should have formal, recognizable technical bases for limits, methods, and personnel protection standards. Procedures should be adequately documented, updated periodically, and maintained in a centralized historical file. A control system should be established to account for all copies and ensure that all new procedures are included in the historical files. A designated period of time for maintaining historical files should be established. ... In addition, radiation protection procedures should have a documented approval system and established intervals for review and/or revision. A tracking system should be developed to ensure that the required reviews and revisions occur. /Plutonium facilities/

A thorough radiation protection training program should be established at ... facilities. Separate training programs should be established for general employees, radiation workers, and radiation control technicians. The training of all staff members should be carefully documented. /Plutonium facilities/

The TLV Physical Agents Committee accepts the occupational exposure guidance of the International Commission on Radiological Protection (ICRP). ... ICRP Guidelines for Exposure to Ionizing Radiation: Effective Dose (a) in any single year, 50 mSv, (b) averaged over 5 years, 20 mSv per year. Annual Equivalent Dose to: (a) lens of the eye, 150 mSv, (b) skin, 500 mSv, (c) hands and feet, 500 mSv. Embryo-Fetus exposures once the pregnancy is known - monthly equivalent dose 0.5 mSv - dose to the surface of women's abdomen (lower trunk) 2 mSv for the remainder of the pregnancy - intake of radionuclide one twentieth of Annual Limit on Intake (ALI). /Ionizing radiation/

The TLV Physical Agents Committee accepts the occupational exposure guidance of the International Commission on Radiological Protection (ICRP). Ionizing radiation includes particulate radiation (e.g., alpha particles and beta particles emitted from radioactive materials, and neutrons from nuclear reactors and accelerators) and electromagnetic radiation (e.g., gamma rays emitted from radioactive materials and x-rays from electron accelerators and X-ray machines) with energy greater than 12.4 electron-volts (eV) ... The guiding principle of radiation protection is to avoid all unnecessary exposures. ICRP has established principles of radiological protection. These are (1) the justification of a work practice: No work practice involving exposure to ionizing radiation should be adopted unless it produces sufficient benefit to the exposed individuals or the society to offset the detriment it causes. (2) The optimization of a work practice: All radiation exposures must be kept as low as reasonably achievable (ALARA), economic and social factors being taken into account. (3) The individual dose limits: The radiation dose from all relevant sources should not exceed the /ICRP/ prescribed dose limits. /Ionizing radiation/

There are 17 isotopes and isomers of americium that are now recognized(1). Americium-232 through 247 are artificially produced and all are radioactive(2).

Radionuclide: Americium-241, Physical Half Life: 458 years. /From table; Americium-241/

Radioactive Half-life: Am-242: 16.02 hours

Radioactive Half-life: Am-242m: 141 years

For more Radiation Limits and Potential (Complete) data for AMERICIUM, RADIOACTIVE (15 total), please visit the HSDB record page.

Protective clothing, commonly of Tyvex material, is used to keep contamination off personal clothing and skin. It does not stop the external radiation exposure (except alpha rays), but it helps prevent the spread of contamination both onto and into the body. /Plutonium facilities/

During operations in which there is a potential to breach a containment system (such as glove changes or seal-outs) and create airborne radioactivity, respiratory protection is the primary method of preventing internal dose from inhalation. To minimize the possibility of inhalation, individuals must ensure the physical integrity of the respirator, obtain a good seal, and ensure the protection factor of the respirator is adequate. There are also methods to prevent injection wounds (such as placing leather gloves over glovebox gloves or ensuring there are no sharp objects inside containments). If personnel have any suspicion of an injection wound, they should immediately seek the assistance of the site radiological control organization. /Plutonium facilities/

In most /emergency/ situations, respiratory protection that is designed to protect responders against chemical or biological agents is likely to offer some degree of respiratory protection in a radiological attack. Concerns about the presence of chemical or biological contaminants will influence the selection of respiratory protection. If used properly, simple face masks provide reasonably good protection against inhaling particulates, and allow sufficient air transfer for working at high breathing rates. If available, high-efficiency particulate air filter masks provide even better protection.

The recommendations in the American National Standards Institute standard, ANSI Z88.2-1992, "American National Standard For Respiratory Protection," are endorsed by the U.S. Nuclear Regulatory Commission and may be used by licensees in establishing a respiratory protection program with the /several/exceptions /including limitations that do not permit or greatly restrict the use of quarter-facepiece respirators and supplied air respirators and self-contained breathing apparatus (SCBA) that operate in the demand mode./

Applicability of OSHA's Respiratory Protection Rules: ... if an NRC licensee is using respiratory protection to protect workers against nonradiological hazards, the OSHA requirements apply. If the NRC has jurisdiction and is responsible for inspection, the ... NRC will inform the licensee and OSHA if the NRC observes an unsafe condition relative to nonradiological hazards. In general, .... if a licensee is in compliance with the NRC regulations in Subpart H, the licensee is considered to be in compliance with the corresponding and comparable OSHA regulations on respiratory protection. ... In situations involving mixed hazards, such as airborne radioactive materials and nonradioactive hazardous materials, compliance with 10 CFR Part 20 alone may not provide sufficient protection.

Treatment reversing the effects of irradiation is currently not possible. Anaesthetics and antiemetics are administered to counter the symptoms of exposure, as well as antibiotics for countering secondary infections due to the resulting immune system deficiency. (L1852)

Absorption of uranium, neptunium, americium, and curium was increased by factors of 3.4, 7.1, 2.7 and 1.7, respectively, when nitrate solutions of these actinides were gavaged to adult rats fed an iron-deficient diet. Retention increased proportionately in liver, kidney and carcass. The concentration of the actinides excreted also increased substantially (over that of controls) in the urine of iron-deficient rats gavaged with uranium-233 and neptunium-237, but not in those with americium-241 or curium-244. Weanling rats on an iron-deficient diet, gavaged with ferric nitrate immediately before administration of plutonium-238 nitrate, retained between 4% and 12% of the plutonium-238 retained by litter mates that were not treated intragastrically with iron. /Americium-241/

TERRESTRIAL FATE: If land deposition occurs, americium will sorb to the soil, leach into the subsurface soil, and redistribute by the action of wind, water, or biotic transport. Americium from fallout is predominantly retained to the upper few centimeters of soil where it is associated with organic matter and bound to manganese and iron oxides(1).

AQUATIC FATE: Americium released to water in effluent, runoff, or atmospheric deposition adsorbs to particulate matter and is rapidly depleted from the water column and deposited in sediment. Adsorption is very high with distribution coefficients between the particulate-associated phase and the dissolved phase in sediment and water of the order of 10X+5 to 10X+6. Colloidal materials can be mobile in groundwater systems for great distances and are capable of binding and transporting radionuclide contaminants, including americium, in subsurface systems. Americium forms stable americium-carbonate complexes in seawater(1). Americium(III) ions hydrolyze and form weak complexes with serum proteins and other ligands. Fish may take up americium, but little builds up in the fleshy tissue(1).

ATMOSPHERIC FATE: Americium released to the atmosphere will be associated with particulate matter and will be deposited on land or surface water by dry or wet deposition. Residence half-times of americium-241 particles in the lower stratosphere range from 3 to 12 months in polar regions and from 8 to 24 months in equatorial regions, with removal being highest in the spring and lowest in the fall. Half-times for particles in the troposphere are about 1 month(1).

Flours that were milled from crops of wheat, rye, barley, and oats grown on German soil where radionuclides resulted exclusively from global fallout contained less than or equal to 5.2, 11, 31, and 70 uBq/kg of americium-241, respectively. The concentration of americium-241 in the bran was a factor of 10-38 higher than in the flour for wheat, rye, and oats(1). Geometric mean concentration ratios of americium-241 (Bq/kg dry plant/Bq/kg dry soil) in the various crops were: corn kernel, 0.0011; corn husk, 0.0016; bush beans, 0.0072; turnip green, 0.0528; and turnip tuber, 0.0053(1).

Assessments of potential internal exposures of the child following radionuclide intakes by the mother require consideration of transfers during lactation as well as during pregnancy. Current ICRP work on internal dosimetry includes the estimation of radiation doses to newborn infants from radionuclides ingested in mothers' milk. ... Comparisons of model predictions show ... americium-241. The corresponding infant doses from milk consumption are estimated in preliminary calculations to be ... <0.1% for ... americium-241. . /Americium-241/

Studies of the transfer of radionuclides to the milk of lactating ewes showed similar levels of transfer for americium-241 and curium-244.

Americium toxicity results primarily from the damage done by the alpha particle emitted during radioactive decay. This alpha particle has very limited penetration in tissue, and hence, the cellular damage occurs only in the immediate vicinity of the sequestered americium. The ionizing radiation produced by americium causes cellular damage that includes DNA breakage, accurate or inaccurate repair, apoptosis, gene mutations, chromosomal change, and genetic instability. This leads to loss of normal cell and tissue homeostasis, and development of malignancy. Ionizing radiation that does not directly damage DNA can produce reactive oxygen intermediates that directly affect the stability of p53, an important enzyme in cell-cycle regulation, and produce oxidative damage to individual bases in DNA and point mutations by mispairing during DNA replication. (L1837)

/AQUATIC SPECIES/ Laboratory radiotracer experiments were performed to study the uptake, assimilation and retention of americium-241 and cesium-134 by the common cuttlefish Sepia officinalis. Uptake and loss kinetics of the radionuclides were measured following exposure through sediments, seawater and food at different stages of the animal's life cycle. Sediment was found to be a minor uptake pathway for both radionuclides in juveniles. Following a short seawater exposure, cuttlefish accumulated 241-Am and 134-Cs, but only to a limited extent (whole-body CF < 2). Among the cuttlefish organs, branchial hearts and their appendages displayed the highest degree of uptake for 241-Am (CF = 42 and 16, respectively), but these tissues contained low percentage of total 241-Am due to their relatively small contribution to whole organism weight. The major fraction of incorporated radionuclides was associated with muscular tissues (viz. 65% and 82% of total 241Am and 134Cs, respectively). Whole-body loss of 241-Am and 134-Cs was relatively rapid (Tb½ = 14 and 6 days, respectively). After dietary exposure, around 60% and 30% of ingested 241-Am was assimilated into the tissues of juvenile and adult cuttlefish, respectively. However, assimilated 241-Am was more strongly retained in adults than in juveniles (Tb½ = 28 vs. 5 days, respectively), suggesting that different mechanisms govern 241Am elimination at both ages. Ingested 134-Cs was assimilated to a similar extent in juveniles (29%) and adults (23%), but the depuration rate was four times faster in adults. /These/ results strongly suggest that these two radionuclides follow different excretion pathways and that the mechanisms can vary with age for a given radionuclide. /Americium-241/

/AQUATIC SPECIES/ The biokinetics of cesium-134 and americium-241 in mussel species contaminated through water pathway has been studied under laboratory conditions. At equilibrium, the concentration factors for cesium-134 and americium-241in small and large mussels were 2.80 and 2.57 and 200 and 150, respectively. The concentration factor of cesium-134 in soft parts of the mussels was significantly high than whole body and shell tissue. However, the concentration factors of americium-241 in soft parts and shell tissue samples were found to have similar rates. The depuration kinetics of the radionuclides were described by two-component exponential models. The biological half-lives at slow components between small and large mussels did not change significant, and were found to be 46.8 to 46.5 and 72.2 to 75.3 days for cesium-134 and americium-241. The depuration kinetics of cesium-134 and americium-241 in soft parts described a single-component exponential model and the biological half-lives were found to be 29.4 and 41.1 days, respectively. /Americium-241/

/OTHER TERRESTRIAL SPECIES/ Adults of the geotrupine beetle Anoplotrupes stercorosus (Coleoptera, Geotrupidae), a common European forest insect species, were used in the role of bio-monitors for mainly man-made radionuclides in a forest environment. Activities of cesium-137, potassium-40, plutonium-238, plutonium(239+240), strontium-90 and americium-241 were studied. Samples originated from four areas in Poland, two from the north-east and two from the south of the country. The north-eastern areas were previously recognized as the places where hot particle fallout from Chernobyl took place. Results confirmed the differences in the activities between north-eastern and southern locations. Significant correlations were found between activities of 40-K and 137-Cs, and between activities of plutonium and americium isotopes. An additional study of the concentration of radionuclides within the bodies of beetles showed a general pattern of distribution of radioisotopes in the insect body. /Cesium-137, potassium-40, plutonium-238, plutonium(239+240), strontium-90 and americium-241/

Vegetation samples collected in 1994 and 1995 from the industrial area of a plant for the utilization and repair of nuclear-powered submarines in the coastal area of Cut Bay in Olenjya Bay in the Kolsky Gulf, Russia contained an americium-241 concentration of 0.2-0.4 Bq/kg of air dry sample(1). Seaweeds collected from the water area of Cut Bay had an americium-241 concentration of 0.2 Bq/kg of moist sample(1). Americium-241 was detected at a mean concentration of 0.299 Bq/kg in mosses collected from Antarctica in 1989-1996(2). Terrestrial moss and tree trunk moss samples collected from the central Italy had a mean americium-241 concentration of 0.0518 Bq/kg and 0.653 Bq/kg, respectively(2). One lichen sample collected from Antarctica had an americium-241 concentration of 1.94 Bq/kg, while the mean concentration in tree trunk lichens collected from central Italy was 0.436 Bq/kg(2).

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1000 curies or 37 TBq. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b). /Americium-237/

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 100 curies or 3.7 TBq. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b). /Americium-238/

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 100 curies or 3.7 TBq. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b). /Americium-239/

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 10 curies or 0.37 TBq. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b). /Americium-240/

For more CERCLA Reportable Quantities (Complete) data for AMERICIUM, RADIOACTIVE (13 total), please visit the HSDB record page.

Americium is a byproduct of plutonium production in nuclear reactors. Americium-241 is used in smoke detectors and in industrial radiography; Also used with beryllium as a neutron source, and as a target material in nuclear reactors and accelerators to synthesize heavier elements; [Argonne] Used in medical diagnosis as a bone mineral analyzer; Used as a radiation source in the treatment of cancer; [Merck Index] A typical household smoke detector contains about 0.9 uCi of Am-241. [ATSDR ToxProfiles]

Soft gamma emission from americium-241 is used to measure the thickness of metal sheets and metal coatings, the degree of soil compaction, sediment concentration in streams, and to induce X-ray fluorescence in chemical analysis. As an alpha emitter, it is mixed with beryllium to produce a neutron source for oil-well logging and to measure water content in soils and industrial process streams. The alpha source is also used to eliminate static electricity and as an ionization source in smoke detectors. /Americium-241/

As target material for production of transcurium elements in high neutron-flux reactors. /Americium-243/

The actinide inventory of radioactive sources consists primarily of radionuclides such as plutonium and americium used in 238Pu-Be and 241Am-Be neutron sealed sources, americium-241gamma sources and plutonium-238Pu heat sources. ... Americium oxides are normally used in sources as americium metal is not stable. For neutron sources, fine americium oxide powder is mixed with beryllium powder. Most neutron sources contain Am-Be in powder or pellet form, but some contain the Am-Be in sintered form. /Am-Be/

Large neutron and gamma sources are used in mining, as well as in oil and gas well logging. These neutron sources contain either 238Pu-Be or 241Am-Be. Californium-252 and a few 226Ra-Be neutron sources are also in use. The activity of some americium-241 neutron sources used in well logging can be as high as several hundreds of GBq per source but are usually within the range of 1 to 800 Gbq /Am-Be/

For more Uses (Complete) data for AMERICIUM, RADIOACTIVE (8 total), please visit the HSDB record page.

Americium can be produced through alpha bombardment of plutonium isotopes and their subsequent beta decay.

The metal is obtained by reduction of the trifluoride with barium in a vacuum at 1200 °C. /Zero valence americium/

Alloys of americium with platinum, palladium, and iridium have been prepared by hydrogen reduction of americium oxide in the presence of the finely divided metals. /Americium alloys/

Americium-241 and americium-243 can be made from uranium-239 or plutonium-239 by neutron activation involving an operating nuclear reactor or nuclear bomb detonation. In this process, neutron activation of uranium-238 can produce uranium isotopes up to at least uranium-241, and each of these beta decays to a neptunium isotope of the same mass. Neutron activation of neptunium can produce isotopes starting with neptunium-239 up through at least neptunium-244, and each of these isotopes beta decays to a plutonium isotope of the same mass. Neutron activation of plutonium isotopes starting with plutonium-239 can produce isotopes through at least plutonium-246, and of these, plutonium-241, plutonium-243, plutonium-245, and plutonium-246 beta decay to americium isotopes of the same mass. /Americium-241, Americium-243, Americium-245, Americium-246/

For more Methods of Manufacturing (Complete) data for AMERICIUM, RADIOACTIVE (6 total), please visit the HSDB record page.

Americium-241: Prepared by dissolution, solvent extraction and ion exchange from plutonium-241; radiopurity >99%, is available as a dioxide powder in gram quantities shipped in welded stainless steel containers meeting special form requirements.

Americium-243 with a radiopurity of >99.9% is available as an oxide powder in milligram quantities shipped in welded stainless steel containers meeting special form requirements. It is produced by transuranic processing from neutron capture on plutonium-242.

Americium: INACTIVE

At the end of their useful life, usually 5 to 15 years, sealed radioactive sources that have applications in medicine, industry, and research are defined as spent or disused. However, the residual level of radioactivity in some sources can still be high, representing a significant radiological hazard. If not properly managed and disposed of, such disused radioactive sources pose a potential health hazard to the public for periods, depending on the half-life and activity level of the radionuclides, which may extend to hundreds or thousands of years. ... The wide range of activities makes it convenient to classify radioactive source strengths as weak (<10 GBq), medium (10 GBq-10TBq) or strong (>10 TBq). Higher activity and longer half-life sources require a greater degree of isolation. Specifically, sources of particular concern for disposal are high activity sources containing cobalt-60, strontium-90, and cesium-137, as well as long lived radium, americium and plutonium sources. /Americium-241/

Americium is a metal of the actinide series which is produced synthetically by neutron activation of uranium or plutonium followed by beta decay. Isotopes Twenty isotopes of americium are known, 232-Am through 248-Am, including three metastable states. All isotopes are radioactive. Americium-243 and 241-Am, alpha emitters, are the longest lived with half-lives of 7,380 years and 432.7 years, respectively. Americium-241 and 243-Am also undergo spontaneous fission. Americium-242m has a half-life of 141 years, and the half-lives of the remaining isotopes are measured in hours, minutes, or seconds. Americium-241 is the most common isotope of environmental concern. /Americium isotopes/

Americium-241 is the only isotope of americium produced for commercial use.

Americium-243 is the longest-lived isotope of americium, with a half-life of 7,370 years.