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La
A symbol for lanthanum.

label
(1) A synonym for labeled atom. (2) A specific nuclide, stable or radioactive, attached to a molecule. Labels are used to track chemical or other processes. For a stable nuclide to be considered a label, the presence of the nuclide must perturb the isotopic ratio normally present in the sample.

labeled compound
A molecule that contains a specific stable or radioactive nuclide.

Synonym: labeled molecule.

lanthanide group
A synonym for lanthanides.

lanthanides
Elements with atomic numbers 58 through 71 (Z=57-71), the elements that follow lanthanum in the periodic chart. The set of lanthanides includes the following elements: cerium (Ce, Z=58); praseodymium (Pr, Z=59); neodymium (Nd, Z=60); promethium (Pm, Z=61); samarium (Sm, Z=62); europium (Eu, Z=63); gadolinium (Gd, Z=64); terbium (Tb, Z=65); dysprosium (Dy, Z=66); holmium (Ho, Z=67); erbium (Er, Z=68); thulium (Tm, Z=69); ytterbium (Yb, Z=70); lutetium (Lu, Z=71).

Synonym: lanthanide group.
Synonym: lanthanide series.
Synonym: lanthanons.
Related to cerium.
Related to dysprosium.
Related to erbium.
Related to europium.
Related to gadolinium.
Related to holmium.
Related to lanthanum.
Related to lutetium.
Related to neodymium.
Related to periodic table.
Related to praseodymium.
Related to promethium.
Related to rare earths.
Related to samarium.
Related to terbium.
Related to thulium.
Related to ytterbium.


lanthanide series
A synonym for lanthanides.

lanthanons
A synonym for lanthanides.

lanthanum
A chemical element with atomic number 57. Lanthanum was discovered in 1839 by Carl Gustaf Mosander who separated its oxide from cerium oxide. The name lanthanum is derived from lanthanein, Greek for that which is hidden.

Symbol: La.
Synonym: (obsolete) ausonium.
Related to cerium earths.
Related to lanthanides.
Related to rare earths.


lawrencium
A chemical element with atomic number 103. Lawrencium was discovered in 1965 by a team of Soviet scientists at the Joint Institute for Nuclear Research in Dubna, Russia. The name lawrencium was given in honor of Ernest O. Lawrence, inventor of the cyclotron.

Symbol: Lr.
Related to actinides.


LCO
An acronym for limiting condition for operation.

LD
An acronym for lethal dose.

LD-50/30
A symbol for median lethal dose 50/30.

LD-50/60
A symbol for median lethal dose 50/60.

lead
A chemical element with atomic number 82. Lead has been known from antiquity. The name lead is derived from plumbum, the Latin meaning heavy.

Symbol: Pb.
Synonym: plumbum.


LET
An acronym for linear energy transfer.

lethal dose
That dose of radiation which is likely to cause death.

Acronym: LD.
Related to dose.


LEU
Acronym for low-enriched uranium.

level scheme
A diagram showing the excited states of a system as horizontal lines and whose vertical position represents the energy of the state. Transitions between excited states are represented as vertical arrows connecting the appropriate excited states.

Synonym: energy level diagram.
Related to decay scheme.


LHGR
An acronym for linear heat generation rate.

Li
A symbol for lithium.

light water
(1) The molecule 1H2O.
(2) Natural water.
(3) Water in which the hydrogen atoms are the nuclide 1H.
(4) A sample of water whose hydrogen consists primarily of the nuclide 1H.

Synonym: heavy water.

light-water reactor
A reactor that uses ordinary water as a moderator and a coolant.

Acronym: LWR.

light work
Work that results in personnel having an inhalation rate of less than 1.2 cubic meters of air per hour.

linear energy transfer
The rate at which a particle loses energy as it passes through matter.

Acronym: LET.

lithium
A chemical element with atomic number 3. Lithium was discovered in 1817 by Johan August Arfvedson. The name lithium is derived from lithos, Greek for stone.

Symbol: Li.
Related to alkali metals.


LLW
An acronym for low-level radioactive waste.

load factor
A synonym for capacity factor.

LOCA
An acronym for loss-of-coolant accident.

LOOP
An acronym for loss of offsite power.

loss-of-coolant accident
Inadvertent escape of water from the primary coolant system.

Acronym: LOCA.

low energy region neutron
A neutron with an energy below 1 eV.

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


low-enriched uranium
A sample of uranium that has a 235U concentration greater than its natural isotopic abundance (0.711%) and less than 20%.

Acronym: LEU.

low-level radioactive waste
Radioactive material that (1) is not high-level radioactive waste, spent nuclear fuel, or by-product material; and (2) the Nuclear Regulatory Commission, consistent with existing law classifies as low-level radioactive waste.

Acronym: LLW.
Synonym: low-level waste.


low-level waste
Synonym for low-level radioactive waste.

low population zone
The area immediately surrounding a reactor in which the population density is kept low for safety concerns.

Acronym: LPZ.

low specific activity
Radioactive material with limited specific activity that satisfies the descriptions and limits set forth in the three low specific activity categories. Shielding materials surrounding the low specific activity material may not be considered in determining the estimated average specific activity of the package contents.

Reference: 10CFR71.
Acronym: LSA.
Related to low specific activity, category I.
Related to low specific activity, category III.
Related to low specific activity, category III.


low specific activity, category I
(1) Ores containing only naturally occurring radionuclides (e.g., uranium, thorium) and uranium or thorium concentrates of such ores.

(2) Solid unirradiated natural uranium or depleted uranium or natural thorium or their solid or liquid compounds or mixtures.

(3) Radioactive material, other than fissile material, for which the A2 value is unlimited.

(4) Mill tailings, contaminated earth, concrete, rubble, other debris, and activated material in which the radioactive material is essentially uniformly distributed, and the average specific activity does not exceed 106 A2/g. Note: A2 Value is the maximum activity of radioactive material, other than special form, LSA and SCO material, permitted in a Type A package.

Acronym: LSA-I.
Related to low specific activity.
Related to low specific activity, category II.
Related to low specific activity, category III.


low specific activity, category II
(1) Water with tritium concentration up to 0.8 TBq/liter (20.0 Ci/liter).

(2) Material in which the radioactive material is distributed throughout, and the average specific activity does not exceed 10 - 4 A2/g for solids and gases, and 10 - 5 A2/g for liquids. Note: A2 Value is the maximum activity of radioactive material, other than special form, LSA and SCO material, permitted in a Type A package.

Reference: 10CFR71.
Acronym: LSA-II.
Related to low specific activity.
Related to low specific activity, category I.
Related to low specific activity, category III.


low specific activity, category III
Solids (e.g., consolidated wastes, activated materials) in which: (1) The radioactive material is distributed throughout a solid or a collection of solid objects, or is essentially uniformly distributed in a solid compact binding agent (such as concrete, bitumen, ceramic, etc.). (2) The radioactive material is relatively insoluble, or it is intrinsically contained in a relatively insoluble material, so that, even under loss of packaging, the loss of radioactive material per package by leaching, when placed in water for 7 days, would not exceed 0.1 A2. (3) The average specific activity of the solid does not exceed 2 x 103 A2/g. Note: A2 value is the maximum activity of radioactive material, other than special form, LSA and SCO material, permitted in a Type A package.

Reference: 10CFR71.
Acronym: LSA-III.
Related to low specific activity.
Related to low specific activity, category I.
Related to low specific activity, category II.


LPZ
An acronym for low population zone.

Lr
A symbol for lawrencium.

LSA
An acronym for low specific activity.

LSA-I
A synonym for low specific activity, category I.

LSA-II
A synonym for low specific activity, category II.

LSA-III
A synonym for low specific activity, category III.

LSSS
An acronym for limiting safety system set point.

Lu
A symbol for lutetium.

lutetium
A chemical element with atomic number 71. Lutetium was discovered in 1907 independently discovered by Carl Auer von Welsbach and Georges Urbain. The name lutetium is derived from Lutetia, Latin for Paris (France).

Symbol: Lu.
Synonym: cassiopeium.
Related to lanthanides.
Related to rare earths.
Related to yttrium earths.


LWR
Acronym for light-water reactor.
 
 
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