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A symbol for triton.

A symbol for tritium.

A symbol for half-life.

A symbol for tantalum.

A synonym for tails.

(1) A waste or by-product from mining or machining processes. In uranium mining it is the crushed ore from which uranium has been extracted. It is also the depleted uranium from which 235U has been isotopically separated.

(2) The sample produced in isotope separation that is depleted in a given isotope.

Synonym: mill tailings.
Synonym: tailing.
Related to isotope separation.

A synonym for reflector.

tank reactor
A reactor design that places the reactor core in a large enclosed tank. Compare with pool reactor.

Related to swimming pool reactor.

A chemical element with atomic number 73. Tantalum was discovered in 1802 by Anders Gustav Ekeberg. The name tantalum is derived from the mythological creature Tantalos, father of Niobe.

Symbol: Ta.
Related to transition metals.

target nucleus
The nucleus in a nuclear reaction on which a projectile particle or radiation is incident.

target nuclide
The initial nucleus in a nuclear reaction on which a projectile is incident. It is used in the context of a nuclear reaction where the projectile interacts with a target nucleus, producing a product nucleus and an ejectile.

Related to ejectile.
Related to product nuclide.
Related to projectile.

A symbol for terbium.

A symbol for technetium.

A symbol for tellurium.

A chemical element with atomic number 43. Technetium was discovered in 1937 at the University of California at Berkeley by Enrico Fermi and Carlo Perrier. The longest lived isotope of technetium is 98Tc which has a half life of 1.5 billion years.

Symbol: Tc.
Synonym: (obsolete) masurium.
Synonym: (obsolete) nipponium.
Related to transition metals.

An acronym for total effective dose equivalent.
Reference: 10CFR20.1003; 10CFR50.2; 10CFR63.2; 10CFR835.2; DOE G 440.1-3; DOE G 441.1-3; DOE G 441.1-11; DOE M 231.1-2; USACHPPM TG 204.

A chemical element with atomic number 52. Tellurium was discovered by Joseph Müller von Reichenstein in 1782 but was not named until Martin Heinrich Klaproth isolated it in 1798. The name tellurium is derived from tellus, Latin for earth.

Symbol: Te.
Related to metalloids.

A chemical element with atomic number 65. Terbium was discovered in 1843 by Carl Gustaf Mosander while he was conducting experiments on the minerals gadolinite and yttria. The name terbium is derived from Ytterby, a town in Sweden, the place of discovery.

Symbol: Tb.
Related to lanthanides.
Related to rare earths.
Related to terbium earths.

terbium earths
Elements with atomic numbers 63 through 66. The set of cerium earths includes the following elements: 63 europium (Eu); 64 gadolinium (Gd); 65 terbium (Tb); 66 dysprosium (Dy).

Related to dysprosium.
Related to europium.
Related to gadolinium.
Related to periodic table.
Related to terbium.

ternary fission
Breakup of a compound nucleus into three fragments of comparable mass.

Related to fission.
Related to fission fragment.
Related to fission neutron.
Related to fission product.
Related to photofission.
Related to spontaneous fission.

An acronym for turbine generator.

An acronym for turbine generator.

A symbol for thorium.

A chemical element with atomic number 81. Thallium was discovered in 1861 by Sir William Crookes who successfully isolated it the following year.

Symbol: Tl.

A symbol for thoron emanation.

thermal breeder reactor
A breeder reactor that uses thermal neutrons to sustain the fission reaction.

thermal fission
Fission induced by thermal neutrons.

thermal neutron
A neutron with an energy approximately equal to 0.025 eV.

Related to cold neutron.
Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to ultra cold neutron.
Related to very cold neutron.

thermal reactor
A reactor in which the fission reaction is sustained primarily by thermal neutrons.

thermal shield
A layer of high-density material placed between the reactor vessel and the biological shield. The thermal shield reduces radiation heating that could damage the biological shield.

thermoluminescence dosimeter
A device that uses electron or hole trapping in inorganic crystals for recording and integrating radiation dose. Ionization produced by radiation in the crystal traps electrons or holes in an excited state of the crystal. The dose is proportional to the number of traps created. Dose is determined by heating the crystal and measuring the light produced when the traps are depopulated. Lithium fluoride (LiF) is a common example of a thermoluminescence dosimeter.

Acronym: TLD.
Synonym: thermoluminescenct dosimeter.

thermoluminescent dosimeter
A synonym for thermoluminescence dosimeter.

Of or pertaining to the use of very high temperatures to initiate the fusion of light nuclei.

Related to nuclear fusion.

A chemical element with atomic number 90. Thorium was discovered in 1828 by Jöns Jakob Berzelius in the mineral monazite. The name thorium is derived from Thor, the Scandinavian god of war.

Symbol: Th.
Related to actinides.

thorium decay series
The nuclides fed in the radioactive decay of 232Th including all daughters through stable 208Pb. Also known as the (4n) series because each member of the series has a mass equivalent to (4n), where n is an integer.

Synonym: thorium series.
Related to actinium decay series.
Related to uranium decay series.

thorium series
A synonym for thorium decay series.

thoron emanation

The nuclide 220Rn.

Symbol: ThEm.

thorough decontamination
Decontamination carried out by a unit, with or without external support, to reduce contamination on personnel, equipment, materiel and/or working areas to the lowest possible levels, to permit the partial or total removal of individual protective equipment and to maintain operations with minimum degradation. This may include terrain decontamination beyond the scope of operational decontamination.

Related to decontamination.
Related to immediate decontamination.
Related to operational decontamination.
Related to radioactive contamination.

A chemical element with atomic number 69. Thulium was discovered in 1879 by Per Teodor Cleve. The name thulium was given in honor of Thule, the ancient name of Scandinavia.

Symbol: Tm.
Symbol: (obsolete) Tu.
Related to lanthanides.
Related to rare earths.
Related to yttrium earths.

A symbol for titanium.

A chemical element with atomic number 50. Tin has been known from antiquity. The name tin is derived from stannum, Latin for dripping and easily melted.

Symbol: Sn.
Synonym: stannum.

tissue equivalent material
Material whose composition approximates that of a given biological tissue.

Synonym: phantom material.
Related to phantom.

tissue weighting factor
A normalization factor applied to equivalent doses to account for different sensitivities of tissues and organs. Tissue weighting factors recommended in ICRP publication 60 are bladder: 0.05; bone surface: 0.01; breast: 0.05; colon: 0.12; esophagus: 0.05; gonads: 0.20; liver: 0.05; lung: 0.12; red bone marrow: 0.12; skin: 0.01; stomach: 0.12; thyroid: 0.05; and remainder: 0.05.

Symbol: wT.
Synonym: organ weighting factor.
Related to radiation weighting factor.
Reference: ICRP Publication 60.

A chemical element with atomic number 22. Titanium was discovered in 1791 by William Gregor. The name titanium was given in honor of Titans, the first sons of the earth.

Symbol: Ti.
Related to transition metals.

A symbol for thallium.

An acronym for thermoluminescence dosimeter.

A symbol for thulium.

An acronym for total organ dose equivalent.

tomic energy
(obsolete term)

A synonym for nuclear energy.

total effective dose equivalent
The sum of the deep-dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures).

Acronym: TEDE.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Reference: 10CFR20.1003; NUREG-0544, Rev. 4.

total organ dose equivalent
The sum of the deep-dose equivalent and the committed dose equivalent for an organ.

Acronym: TODE.
Related to committed dose equivalent.
Related to deep-dose equivalent.
Related to dose.

A nuclide incorporated into a molecule to provide information on chemical processes and pathways. The tracer can be radioactive or an enriched stable isotope of an element.

Synonyms: indicator; isotope tracer; isotopic indicator; isotopic tracer.

tracer, isotopic
See instead isotopic tracer.

Any person within inhabited building distance but not inside an explosives bay or other occupied areas (offices, break area, shops, etc.).

transient equilibrium
A type of radioactive equilibrium in which the parent nuclide has a half-life that is longer but comparable to its radioactive daughter. The activity of the daughter will decrease over time and will be proportional to that of the parent.

Related to equilibrium.
Related to radioactive equilibrium.
Related to secular equilibrium.

transition metals
The set of chemical elements in groups IB through VIIB and group VIII in the periodic table. The transition metals includes the elements scandium (Sc, Z=21), titanium (Ti, Z=22), vanadium (V, Z=23), chromium (Cr, Z=24), manganese (Mn, Z=25), iron (Fe, Z=26), cobalt (Co, Z=27), nickel (Ni, Z=28), copper (Cu, Z=29), zinc (Zn, Z=30), yttrium (Y, Z=39), zirconium (Zr, Z=40), niobium (Nb, Z=41), molybdenum (Mo, Z=42), technetium (Tc, Z=43), ruthenium (Ru, Z=44), rhodium (Rh, Z=45), palladium (Pd, Z=46), silver (Ag, Z=47), cadmium (Cd, Z=48), hafnium (Hf, Z=72), tantalum (Ta, Z=73), tungsten (W, Z=74), rhenium (Re, Z=75), osmium (Os, Z=76), iridium (Ir, Z=77), platinum (Pt, Z=78), gold (Au, Z=79), mercury (Hg, Z=80), rutherfordium (Rf, Z=104), dubnium (Db, Z=105), seaborgium (Sg, Z=106), bohrium (Bh, Z=107), hassium (Hs, Z=108), meitnerium (Mt, Z=109), ununnilium (Uun, Z=110), unununium (Uuu, Z=111), and ununbium (Uub, Z=112).

Related to the following terms:
bohriumcadmiumchromiumcobaltcopperdubniumgoldhafniumhassiumiridiumironmanganesemeitneriummercurymolybdenumnickelniobiumpalladiumosmiumperiodic tableplatinumrheniumrhodiumrutheniumrutherfordiumscandiumseaborgiumsilvertantalumtechnetiumtitaniumtungstenvanadiumyttriumzinczirconium

Modifying the nucleus of an atom by bombardment with nuclear particles.

Synonym: atomic transmutation.

transuranic element
An element above uranium in the periodic table, one with an atomic number greater than 92.

Synonym: transuranium element.
Related to transuranium radionuclide.

transuranic waste
Without regard to source or form, waste that is contaminated with alpha-emitting transuranium radionuclides with half-lives greater than 20 years and concentrations greater than 100 nCi/g at the time of assay. Heads of Field Elements can determine that other alpha contaminated wastes, peculiar to a specific site, must be managed as transuranic waste.

Synonym: TRU waste.

transuranium element
A synonym for transuranic element.

transuranium radionuclide
Any radionuclide having an atomic number greater than 92.

Related to transuranic element.

Any method, technique, or process designed to change the physical or chemical character of waste to render it less hazardous, safer to transport, store or dispose of, or reduced in volume.

A synonym for scram.

triplet state
A configuration in which the spins of two particles are oriented parallel.

Related to singlet state.

triplet state annihilation
Annihilation of a triplet positronium, an atom-like structure in which the positron and electron spin s are parallel. This form of annihilation produces three photons.

Synonym: three photon annihilation
Related to ortho positronium.
Related to singlet state annihilation.

An isotope of hydrogen with a single proton and two neutrons. Tritium is radioactive with a half-life of 12.33 years. It is found in nature as a result of the interaction of cosmic rays in the upper atmosphere. A tritium nucleus is called a triton.

Symbol: 3H.
Symbol: T.
Related to deuterium.
Related to hydrogen.
Related to triton.

The nucleus of tritium, 3H.

Symbol: t.
Related to tritium.

TRU waste
Synonym for transuranic waste.

An acronym for technical specification.

(obsolete term)

A symbol for thulium.

A chemical element with atomic number 74. Tungsten was discovered in 1783 by Don Fasto d'Elhuyar and Juan José d'Eluhyar. The name tungsten is derived from tung sten, Swedish for heavy stone.

Symbol: W.
Synonym: wolfram.
Related to transition metals.

two photon annihilation
A synonym for singlet state annihilation.

type B package
Type B packaging together with its radioactive contents. On approval, a Type B package design is designated by the Nuclear Regulatory Commission as B(U) unless the package has a maximum normal operating pressure of more than 700 kPa (100 lb/in2) gauge or a pressure relief device that would allow the release of radioactive material to the environment under the tests specified in 10CFR part 71.73 (hypothetical accident conditions), in which case it will receive a designation of B(M). The term B(U) refers to the need for unilateral approval of international shipments; the term B(M) refers to the need for multilateral approval of international shipments. There is no distinction made in how packages with these designations may be used in domestic transportation. To determine their distinction for international transportation, see Department of Transportation regulations in 49CFR part 173. A Type B package approved before September 6, 1983, was designated only as Type B. Limitations on its use are specified in 10CFR part 71.,13.

Reference: 10CFR71.
Related to package.
Related to fissile material package.
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