Transuranic waste (TRU) is stated by U.S. regulations, and independent of state or origin, to be waste which has been contaminated with
alpha emitting transuranic radionuclides possessing
half-lives
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
greater than 20 years and in concentrations greater than 100
nCi/g (3.7
MBq
''MBQ'' is an original English-language manga created by Tokyopop's Rising Stars of Manga second-place winner Felipe Smith.
''MBQ'' is an expansion of his second-place winning entry in the third Rising Stars competition. It is the story of a y ...
/kg).
Elements having
atomic numbers
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of ever ...
greater than that of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
are called transuranic. Elements within TRU are typically man-made and are known to contain
americium-241 and several isotopes of
plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exh ...
.
Because of the elements' longer
half-lives
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
, TRU is disposed of more cautiously than
low level waste and intermediate level waste. In the U.S. it is a byproduct of weapons production, nuclear research and power production, and consists of protective gear, tools, residue, debris and other items contaminated with small amounts of radioactive elements (mainly plutonium).
Under U.S. law, TRU is further categorized into "contact-handled" (CH) and "remote-handled" (RH) on the basis of the radiation field measured on the waste container's surface. CH TRU has a surface dose rate not greater than 2
mSv
mSv or MSV may refer to:
* Maize streak virus, a plant disease
* Medium-speed vehicle, US category
* Medium Systems Vehicle, a class of fictional artificially intelligent starship in The Culture universe of late Scottish author Iain Banks
* Millis ...
per hour (200
mrem
The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body.
Quantities measu ...
/h), whereas RH TRU has rates of 2 mSv/h or higher. CH TRU has neither the high radioactivity of high level waste, nor its high heat generation. In contrast, RH TRU can be highly radioactive, with surface dose rates up to 10 Sv/h (1000 rem/h).
The United States currently permanently disposes of TRU generated from defense nuclear activities at the
Waste Isolation Pilot Plant
The Waste Isolation Pilot Plant, or WIPP, is the world's third deep geological repository (after Germany's Repository for radioactive waste Morsleben and the Schacht Asse II salt mine) licensed to store transuranic radioactive waste for 10,00 ...
, a deep geologic repository.
Other countries do not include this category, favoring variations of High, Medium/Intermediate, and Low Level waste.
References
{{reflist
External links
Final Environmental Assessment for Actinide Chemistry and Repository Science Laboratory - Citing a DOE TRU DefinitionUS Department of Energy's page on the Waste Isolation Pilot Plant (WIPP)
Radioactive waste