radioactive equilibrium

WordNet

1. a stable situation in which forces cancel one another
2. a sensory system located in structures of the inner ear that registers the orientation of the head (同)labyrinthine sense, vestibular sense, sense of balance, sense_of_equilibrium
3. exhibiting or caused by radioactivity; "radioactive isotope"; "radioactive decay"; "radioactive fallout"

PrepTutorEJDIC

1. (力・勢力・作用などの)釣り合い,均衡;(心の)平静
2. (光・熱を)放射する / 発光する,発熱する
3. 放射性の,放射能のある(による)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/01 12:40:08」(JST)

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In nuclear physics, secular equilibrium is a situation in which the quantity of a radioactive isotope remains constant because its production rate (e.g., due to decay of a parent isotope) is equal to its decay rate.

Secular equilibrium in radioactive decay

Secular equilibrium can only occur in a radioactive decay chain if the half-life of the daughter radionuclide B is much shorter than the half-life of the parent radionuclide A. In such a situation, the decay rate of A, and hence the production rate of B, is approximately constant, because the half-life of A is very long compared to the timescales being considered. The quantity of radionuclide B builds up until the number of B atoms decaying per unit time becomes equal to the number being produced per unit time; the quantity of radionuclide B then reaches a constant, equilibrium value. Assuming the initial concentration of radionuclide B is zero, full equilibrium usually takes several half-lives of radionuclide B to establish.

The quantity of radionuclide B when secular equilibrium is reached is determined by the quantity of its parent A and the half-lives of the two radionuclide. This can be seen from the time rate of change of the number of atoms of radionuclide B:

,

where λ_A and λ_B are the decay constants of radionuclide A and B, related to their half-lives t_1/2 by , and N_A and N_B are the number of atoms of A and B at a given time.

Secular equilibrium occurs when , or

.

Over long enough times, comparable to the half-life of radionuclide A, the secular equilibrium is only approximate; N_A decays away according to

,

and the "equilibrium" quantity of radionuclide B declines in turn. For times short compared to the half-life of A, and the exponential can be approximated as 1.

See also

• Bateman Equation
• Transient equilibrium

References

• IUPAC definition
• EPA definition

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English Journal

• A method for optimum PSA setting in the absence of a pure α or β emitter and its application in the determination of (237)Np/(233)Pa.

• Feng XG1, He QG2, Wang JC2, Chen J2.
• Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.Appl Radiat Isot.2014 Nov;93:114-9. doi: 10.1016/j.apradiso.2014.01.029. Epub 2014 Feb 12.
• In the application of liquid scintillation counting (LSC), the α/β discrimination is carried out with the function of pulse shape analysis (PSA), which requires the setting of the optimum PSA level. The optimum PSA are usually determined by the generation of cross-over plots, whereby a pair of via
• PMID 24582116

• Development of a fluorescence assay for the characterization of brevenal binding to rat brain synaptosomes.

• McCall JR1, Goodman AJ, Jacocks HM, Thompson AM, Baden DG, Bourdelais AJ.
• Journal of natural products.J Nat Prod.2014 Sep 26;77(9):2014-20. doi: 10.1021/np500118p. Epub 2014 Sep 17.
• The marine dinoflagellate Karenia brevis produces a family of neurotoxins known as brevetoxins. Brevetoxins elicit their effects by binding to and activating voltage-sensitive sodium channels (VSSCs) in cell membranes. K. brevis also produces brevenal, a brevetoxin antagonist, which is able to inhib
• PMID 25226846

Japanese Journal

• 放射平衡とサイコロを使ったモデル実験

• 小倉 昭弘
• 物理教育 63(1), 26-29, 2015-03-13
• NAID 110009923807

• Removal of iodide from water by chlorination and subsequent adsorption on powdered activated carbon

• Ikari Mariya,Matsui Yoshihiko,Suzuki Yuta,Matsushita Taku,Shirasaki Nobutaka
• Water research 68, 227-237, 2015-01-01
• … Chlorine oxidation followed by treatment with activated carbon was studied as a possible method for removing radioactive iodine from water. …
• NAID 120005553677

• 放射性Cs汚染地域におけるエネルギー作物生産およびガス化発電利用に関する基礎検討とケーススタディ

• 松本 啓吾,武野 計二,大島 義人 [他],小林 真
• 化学工学論文集 41(1), 48-54, 2015
• 福島第一原子力発電所事故による放射性物質汚染地域の有効活用のため，草本系エネルギー作物であるエリアンサスを栽培し，ガス化発電するシステムを想定した基礎検討として，ガス化炉を模擬した管型試験炉を用いた基礎試験および平衡計算結果をもとに，放射性物質で最も危険性が憂慮されるCsの各機器への移行について評価した．エリアンサスを用いた管型試験炉による基礎試験の結果，電気炉後流の冷却過程におけるCs回収率は， …
• NAID 130004855803

Related Links

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• Radioactive Equilibrium - Radioactivity.eu.com

Establishing a radioactive equilibrium The radioactive equilibrium takes about 2 million years to form in the lineage of uranium 238, at which point the activities of these descendants become equal to that of uranium 238. The short half ...

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「放射平衡」

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英

radioactive equilibrium

同

放射能平衡

「equilibrium」

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• n.

• 平衡、平衡状態、平衡感覚

関

balance、balanced、equilibrated、equilibration、equilibria、equilibrium state

　 　 　

「radioactive」

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• 放射性の、放射活性のある

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