Plutonium

2022-08-26

Plutonium is a transuranic radioactive chemical element with symbol Pu and atomic number 94. It is an actinide metal of silvery-grey appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous. [1] Very small amounts of plutonium occur naturally. Plutonium-239 and plutonium-240 are formed in nuclear power plants when uranium-238 captures neutrons. [2]

Uses [3]

Plutonium is a key fissile component in modern nuclear weapons; care must be taken to avoid accumulation of amounts of plutonium which approach critical mass, the amount of plutonium which will self-generate a nuclear reaction. Despite not being confined by external pressure as is required for a nuclear weapon, it will nevertheless heat itself and break whatever confining environment it is in. Shape is relevant; compact shapes such as spheres are to be avoided. Plutonium could also be used to manufacture radiological weapons. The plutonium isotope 238Pu is an alpha emitter with a half-life of 87 years. These characteristics make it well suited for electrical power generation for devices which must function without direct maintenance for timescales approximating a human life time. It is therefore used in RTGs such as those powering the Galileo and Cassini space probes. Plutonium-238 was used on the Apollo-14 lunar flight in 1971 to power seismic devices and other equipment left on the Moon, and it was also the power supply of the two Voyager supercraft launched in 1977. Plutonium-239 can also be used as a fuel in a new generation of fast-breeder nuclear weapons, which burn a mixed oxide (MOX) fuel consisting of uranium and plutonium.

In the Environment [4]

Plutonium released during atmospheric testing of nuclear bombs, which ended in 1980, is the source of most of the plutonium in the environment worldwide.

Plutonium is also released to the environment from research facilities, waste disposal, nuclear fuel reprocessing facilities, nuclear weapons production facilities, and accidents at facilities where plutonium is used.

Plutonium can be transported in the atmosphere.

It can be deposited on land or water by settling or by precipitation.

Plutonium can stick to particles in soil, sediment, and water.

Plutonium will undergo radioactive decay in the environment.

Sources & Routes of Exposure

Sources of Exposure [4]

Everyone is exposed to very low levels of plutonium in air, and possibly in drinking water and food.

Exposure to higher levels could occur from an accidental release during its use.

Exposure during transport and disposal is unlikely because transport containers are virtually indestructible by accident or fire; disposal sites are deep underground and away from the public.

Workers at nuclear facilities using plutonium may be exposed to higher levels of it.

People who live near facilities that use plutonium in their operations may be exposed to it from accidental releases to the air.

Routes of Exposure [5]

Inhalation – The exposure route of primary concern for workers and the general population.

Oral – Minor route of exposure.

Dermal – Minor route of exposure

Health Effects [3]

The alpha radiation plutonium emits does not penetrate the skin, but can irradiate internal organs it is inhaled or ingested.

Extremely small particles of plutonium on the order of micrograms can cause lung cancer if inhaled into the lungs.

Considerably larger amounts may cause acute radiation poisoning and death if ingested or inhaled; however, so far, no human is known to have died because of inhaling or ingesting plutonium and many people have measurable amounts of plutonium in their bodies.

When people breathe it in, plutonium may remain in the lungs or move to the bones or organs. Generally, it stays in the body for a long time and continually exposes body tissues to radiation. After a few years this could result in the development of cancer.

Furthermore, plutonium may affect the ability to resist disease and the radioactivity from plutonium may cause reproductive failure.

Safety [6]

First Aid Measures

Inhalation: Remove from exposure area to a restricted area with fresh air as quickly as possible. If breathing has stopped, perform artificial respiration by administering oxygen; mouth-to-mouth resuscitation should be avoided to prevent exposure to the person rendering first aid. Any evidence of serious contamination indicates that treatment must be instituted. (Inhalation of radioactive particles may indicate that other parts of the body were also contaminated, such as the digestive tract, skin and eyes.) If time permits, wipe the face with wet filter paper, force coughing and blowing of the nose. Get medical attention immediately. The victim may be contaminated with radioactive particles. Thorough decontamination should be started before the victim is moved to the medical area. Any personnel involved in rendering first aid must be monitored for radioactivity and thoroughly decontaminated if necessary.

Skin Contact: Remove victim to a suitable area for decontamination as quickly as possible. Remove clothing and shoes immediately. Thoroughly wash the victim with soap and water, paying particular attention to the head, fingernails and palms of the hands. Upon completion of washing, monitor the victim for radioactivity. It is imperative that the skin should be decontaminated as quickly as possible. Minute skin injuries greatly increase the danger of isotope penetration into the victim; shaving should not be attempted. If water and soap have been inadequate in removing the radioactive compound, decontaminating compounds consisting of surfactants and absorbent substances may be effective. Complexing reagents may also be of use. The use of organic solvents is to be avoided, as they may increase the solubility and absorption of the radioactive substance. Skin contamination with radioactivity may be an indication that other parts of the body have been exposed. Contaminated clothing must be stored in an airtight, chemically compatible container for later decontamination or disposal. The water used to wash the victim must be stored in an airtight, chemically compatible container for later disposal. Any personnel involved in rendering first aid to the victim must be monitored for radioactivity and decontaminated if necessary.

Eye Contact: Remove victim to a restricted area for decontamination. Thoroughly wash eyes with large amounts of water, occasionally lifting the upper and lower lids (approximately 15 minutes). Following the water treatment, provide an isotonic solution. Do not use eyebaths, rather provide a continuous and copious supply of fluid. Monitor the victim for radioactivity. If activity is present, rewash the eyes, and remonitor until little or no radioactivity is present. Get medical attention immediately. Any water used to wash the victim’s eyes must be stored in an airtight, chemically compatible container for later disposal. Any other articles that are used to decontaminate the victim must also be stored in similar containers for later decontamination or disposal. Any personnel involved in rendering first aid to the victim must be monitored for radioactivity and decontaminated if necessary.

Ingestion: In the case of ingestion of radioactive substances, the mouth should be rinsed out immediately after the accident, care being taken not to swallow the water used for this purpose. Vomiting should be induced either mechanically, or with syrup of ipecac. Do not induce vomiting in an unconscious person. Lavage may be useful. Care should be taken to avoid aspiration. The vomitus and lavage fluids should be saved for examination and monitoring. Get medical attention immediately. The gastric fluids and fluids used for lavage must be stored in airtight, chemically compatible containers for later disposal. The victim must be monitored for radioactivity and decontaminated, if necessary, before being transported to a medical facility. Any personnel involved in rendering first aid to the victim must be monitored for radioactivity and decontaminated if necessary.

Fire Information

Negligible fire hazard in bulk form; however, dust, powder, or fumes are flammable or explosive when exposed to heat or flames.

Small fires should be extinguished with Metal-X (Class D) fire extinguisher.

Do not move damaged containers; move undamaged containers out of fire zone. Contact the local, State, or Department of Energy radiological response team. Use suitable agent for surrounding fire. Cool containers with flooding amounts of water, apply from as far a distance as possible. Avoid contamination of water sources and sewers. Avoid breathing dusts or vapours, keep upwind. Keep unnecessary people out of area until declared safe by radiological response team.

Exposure Controls and Personal Protection

At a minimum, provide process enclosure ventilation. Depending upon work activities, a more stringent ventilation system may be necessary to comply with exposure limits.

A High Efficiency Particulate Air (HEPA) filtration system may be required for handling and storing this material.

One method of controlling external radiation exposure is to provide adequate shielding. The absorbing material used and the thickness required to attenuate the radiation to acceptable levels depends on the type of radiation, its energy, the flux and the dimensions of the source.

Alpha Particles: For the energy range of alpha particles usually encountered, a fraction of a millimetre of any ordinary material is sufficient for absorbance. Thin rubber, acrylic, stout paper, or cardboard will suffice.

Beta Particles: Beta particles are more penetrating than alpha, and require more shielding. Materials composed mostly of elements of low atomic number such as acrylic, aluminium and thick rubber are most appropriate for the absorption of beta particles. For example, 1/4 inch of acrylic will absorb all beta particles up to 1 MeV.

Gamma Rays: The most suitable materials shielding gamma radiation are lead and iron. The thickness required will depend on whether the source is producing narrow or broad beam radiation. Primary and secondary protective barriers may be required to block all radiation.

Eye Protection: Employee must wear appropriate eye protection that will not allow the introduction of particles into the eyes. Contact lenses should not be worn.

Clothing, glove and eye protection equipment will provide protection against alpha particles, and some protection against beta particles, depending on thickness, but will not shield gamma radiation.

Clothing: Overgarments, including head coverings and foot covering, should be worn by any employee engaged in handling radioactive substances. These garments are also recommended even if the employee is working with a “glovebox” containment system. Certain clothing fibres may be useful in dosimetry so clothing should be kept. In the event of an accident, large scale release or a large scale clean-up, full protective clothing will be necessary.

Gloves: Employee must wear appropriate protective gloves to prevent contact with this substance. Used gloves may present a radioactive contamination hazard and should be disposed of as radioactive waste.

Respirator: Respirators should provide protection for the respiratory tract against inhalation of most of the radioactive particles encountered in the workplace. Respirators will not offer protection against beta and gamma radiation, but will block alpha particles. Respiratory equipment must be jointly certified by NIOSH/MSHA. The following respiratory protection is recommended. Lower levels of protection may be appropriate depending on containment systems. Consult a qualified health physicist for more information.

General conditions: Type ‘C’ supplied-air respirator with a full face-piece operated in pressure-demand or other positive pressure mode or with a full face piece, helmet or hood operated in continuous-flow mode.

Self-contained breathing apparatus with a full face piece operated in pressure-demand or other positive pressure mode.

For firefighting and other immediately dangerous to life or health conditions: Self-contained breathing apparatus with full face piece operated in pressure-demand or other positive pressure mode.

Supplied-air respirator with full face piece and operated in pressure-demand or other positive pressure mode in combination with an auxiliary self-contained breathing apparatus operated in pressure-demand or other positive pressure mode.

Regulation

United States [2]

The U.S. Nuclear Regulatory Commission (USNRC) has recommended the following radiation exposure limits for the general public and for workers:

General public

0.1 rem/year for the general public and 0.5 rem/year for people who work with patients in nuclear medicine. These regulations are for all forms of radiation combined, so they are not only for plutonium.

Workers

5 rem/year for workers in industries where exposure to radiation may occur and 0.5 rem for the pregnancy period following the declaration of pregnancy by a woman in an industry where exposure to radiation may occur.

These recommended radiation exposure limits are for all forms of radiation combined and are not specific to plutonium. The limits are expressed in units called rem (roentgen equivalent man). A rem is a radiation unit that expresses the radiation equivalent dose to a particular organ or tissue. The limits on equivalent dose are used to calculate the limits on the amount of radioactive substances that can be inhaled or ingested.

References

https://en.wikipedia.org/wiki/Plutonium

http://www.atsdr.cdc.gov/phs/phs.asp?id=646&tid=119

http://www.lenntech.com/periodic/elements/pu.htm

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=647&tid=119

http://www.atsdr.cdc.gov/toxguides/toxguide-143.pdf

http://science.energy.gov/~/media/nbl/pdf/price-lists/SDS/SDS-Plutonium_Metal.pdf