WordNet
- a stable situation in which forces cancel one another
- 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
- exhibiting or caused by radioactivity; "radioactive isotope"; "radioactive decay"; "radioactive fallout"
PrepTutorEJDIC
- (力・勢力・作用などの)釣り合い,均衡;(心の)平静
- (光・熱を)放射する / 発光する,発熱する
- 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)
[Wiki en表示]
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 λA and λB are the decay constants of radionuclide A and B, related to their half-lives t1/2 by , and NA and NB 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; NA 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
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- PMID 24582116
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- McCall JR1, Goodman AJ, Jacocks HM, Thompson AM, Baden DG, Bourdelais AJ.
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- PMID 25226846
Japanese Journal
- 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
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- 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
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