Lecture 13 - 1 Radon NSS and Non-conservative MFB ...

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Unformatted text preview: 1 Radon: NSS and Non-conservative MFB ¡ Lecture#13 ¡ review reaction kinetics ¡ radioactive decay (1 st order kinetics) ¡ non steady state (NSS), non conservative (CMFR) ¡ ICP #11 ¡ Reading V: Ch 5 (pg. 98-100; 110-111); Handout DFE2; Radon Guide Posted on Website What you should learn today ¡ Why is radon a problem in homes? ¡ Can we fix the radon problem? ¡ How do we set up and solve non steady-state, non-conservative CMFR problems? Reaction kinetics ¡ R = rate of reaction (mass/volume-time ≡ g/L-d) ¡ m ● rxn = ± VR → units of mass flow ( ≡ g/d); − for decay; + generation ¡ R = kC n Where k is the rate constant, n is the order of reaction, and C is the contaminant concentration ¡ reaction order, n n=0; zero order n=1; first order n=2; second order ¡ unit of k → depends on order such that kC n will give units of g/L-d n=0; k ≡ g/L-d n=1; k ≡ 1/d n=2; k ≡ L/g-d Batch with 1 st order reaction kinetics ¡ for no flow reaction: dm/dt = m ● rxn = ± VR ¡ R = kC n ¡ for 1 st order reaction, n=1, R = kC (k ≡ 1/d) ¡ dm/dt = VdC/dt = -VkC (for decay) ¡ dC/dt = -kC → dC/C = -kt (integrate) ¡ C=C exp(-kt) dm/dt = VdC/dt = m ● in- m ● out + m ● rxn ICP#10 (review) ¡ C = C CO exp(-k Co t) + C Cr exp(-k Cr t) ¡ t ½ = 0.693/k Co = (0.693/5.263 yr)(1yr/365d) k Co =3.6x10-4 d-1 ¡ t ½ =0.693/k Cr = (0.693/26.5d) k Cr =2.6x10-2 d-1 ¡ C Co = 1x10-3 Ci/L; C Cr = 1 Ci/L C = 100 μ Ci/L when t = 17.5 yr (dictated by decay rate of 60 Co ( 51 Cr reaches 100 μ Ci after 1 yr) ICP#10 (cont.) Radioactive Decay 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 5 10 15 20 Time, years C u r i e s Total Cobalt Chromium...
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Lecture 13 - 1 Radon NSS and Non-conservative MFB ...

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