2.
RADIOACTIVITY PRODUCTIONS IN NUCLEAR REACTORS

2.1 RADIOACTIVE SPECIES IN LIGHT WATER REACTORS

There are approximately one hundred major radioactive nuclides which can be found in a reactor system (see Appendix A, Table A-1). Each nuclide decays with emission from the nucleus of characteristic energetic elementary particles or energetic photons. In some cases, the change is accomplished by the capture by the nucleus of an extra-nuclear electron.

The various decay processes and the particles and radiations emitted are:

Decay Process

Radiation Emitted

Mass (amu)

Electrical Charge

Typical Energy (MeV)

Alpha Emission

Alpha particle (α)

4

+2

4–9

Beta Emission

Beta particle (ß)

0.0005

−1

0–3

Positron Emission

Positron (ß+)

0.0005

+1

0–3

 

Two gamma-rays (γ)

0

0

0.51

Electron Capture

Characteristic x-ray

0

0

0–0.1

Internal Transition

Gamma-ray (γ)

0

0

0.1–3

Internal Conversion

Converted electron (e)

0.0005

−1

0.1–1

 

Characteristic x-ray

0

0

0.0–1

Neutron Emission

Neutron (n)

1

0

0–14

Spontaneous Fission (e.g., Cf-252)

Fission products and other radiations

≈200



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Radiochemistry in Nuclear Power Reactors 2. RADIOACTIVITY PRODUCTIONS IN NUCLEAR REACTORS 2.1 RADIOACTIVE SPECIES IN LIGHT WATER REACTORS There are approximately one hundred major radioactive nuclides which can be found in a reactor system (see Appendix A, Table A-1). Each nuclide decays with emission from the nucleus of characteristic energetic elementary particles or energetic photons. In some cases, the change is accomplished by the capture by the nucleus of an extra-nuclear electron. The various decay processes and the particles and radiations emitted are: Decay Process Radiation Emitted Mass (amu) Electrical Charge Typical Energy (MeV) Alpha Emission Alpha particle (α) 4 +2 4–9 Beta Emission Beta particle (ß−) 0.0005 −1 0–3 Positron Emission Positron (ß+) 0.0005 +1 0–3   Two gamma-rays (γ) 0 0 0.51 Electron Capture Characteristic x-ray 0 0 0–0.1 Internal Transition Gamma-ray (γ) 0 0 0.1–3 Internal Conversion Converted electron (e−) 0.0005 −1 0.1–1   Characteristic x-ray 0 0 0.0–1 Neutron Emission Neutron (n) 1 0 0–14 Spontaneous Fission (e.g., Cf-252) Fission products and other radiations — — ≈200

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Radiochemistry in Nuclear Power Reactors The decay of a radioactive species is a random process dependent only on the number of radioactive atoms present at a given time (i.e., the decay rate is a first-order reaction): (2–1) Upon integration, the result can be written as (2–2) where N=number of atoms present at time t;   No=number of atoms present at t=0;   λ=decay constant. The constant λ is the characteristic decay constant for the radioactive species. The characteristic rate of radioactive decay may conveniently be stated in terms of the half-life (t1/2), which is the time required for an initial number of atoms to be reduced to half that number by decay. A sample of any radioactive substance which is decaying at the rate of 3.7×1010 disintegration per second is traditionally said to contain one curie (Ci) of radioactivity. A millicurie (mCi) is 10−3 curies and a microcurie (μCi) is 10−6 curies. The microcurie is probably the most frequently used activity unit in the nuclear industry. The SI unit for the activity is Becquerel (Bq). One Bq is equal to one disintegration per second of activity, thus one Ci equals 3.7×1010 Bq.

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Radiochemistry in Nuclear Power Reactors The concentrations of radioactive species in different types of samples may be expressed in different ways. For example: Sample Form Recommended Expression Recommended Unit Liquid Concentration μCi/L or Bq/mL Reactor water or condensed steam Concentration μCi/kg or Bq/gm Gas Concentration μCi/cc or Bq/cc Solid Solid concentration μCi/gm or Bq/gm of specified solid substance Surface Surface concentration µCi/cm2 or Bq/cm2 Any form of target substance Specific activity μCi/gm or Bq/gm of target element It should be noted that the activity concentration in reactor water or condensed steam is commonly reported in μCi/kg or Bq/gm. Using the mass instead of volume avoids the confusion of water density differences at different temperatures. The radioactive species may be produced in a reactor by different nuclear reactions from various target materials in the system. 2.2 NUCLEAR FISSION The fission process is usually accompanied by the emission of neutrons and much more rarely by the emission of a particles and possibly other light fragments. Tritium is also emitted in some fission processes. Fission has been produced in some nuclides (notably U-235, U-238, and Th-232) by neutrons, protons, deuterons, helium ions, and γ and x-rays of moderate energies. In a reactor by far the most important of these reactions is neutron-produced fission. The species U-232, U-233, U-235, Pu-239, Am-241, and Am-242 undergo fission either with thermal or fast neutrons, whereas fission of U-238 requires fast neutrons.

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Radiochemistry in Nuclear Power Reactors 2.2.1 Mass Distribution and Fission Product Chains The fission process may occur in many different modes, and a very large number of fission products, ranging from Z=30 (zinc) to Z=65 (terbium) and from A=72 to A=161 in the thermal neutron fission of U-235, are known. Fission into two equal fragments is by no means the most probable mode in thermal-neutron fission. Asymmetric modes are much more favored, the maximum fission product yields occurring at A=95 and A=138. The asymmetry appears to become less pronounced with increasing bombarding energy. When the total fission yield at each mass number is plotted against mass number, the curve shown in Figure 2–1 results. The curve is essentially symmetrical about the minimum at A=233.5/2 and has two rather broad maxima around mass numbers 95 and 138. The yields in each of the two peaks sum to approximately 100%. Sufficient information is available on the fission yields in the thermal-neutron fission of Pu-239 to draw a mass-yield curve for this case. The general shape is similar to the U-235 curve, but there are certain significant differences (see Figure 2–1). The yield at the minimum is not as low as for U-235; it is about 0.04 percent of the fission yield at A=119. The heavy peak appears not to be appreciably displaced, compared to U-235 fission, but the light peak has its maximum at about A=99. An enormous amount of radiochemical work was required to arrive at the present state of knowledge about fission products. It was necessary to develop chemical separation procedures, to analyze radioactive decay and growth patterns, to determine beta- and gamma-ray energies, to establish mass assignments of many previously unknown nuclides and to measure the fission yields. The fission yield of a nuclide is the fraction or the percentage of the total number, of fissions which lead directly or indirectly to that nuclide. As would be expected from the different neutron-proton ratios for U-235 and the stable elements in the fission product region, the primary products of fission are generally on the neutron-excess side of stability. Each such product decays by successive ß− processes to a stable isobar. Chains with as many as six β− decays have been established, and undoubtedly some fission products still further removed from stability (higher on the parabolic slope of the stability valley) have escaped detection because of their very short half-lives. No neutron-deficient nuclides have been found among the products of thermal-neutron fission.

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Radiochemistry in Nuclear Power Reactors Figure 2–1. Yields of Fission Product Chains as a Function of Mass Number for the Thermal-Neutron Fission of U-235 and Pu-239

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Radiochemistry in Nuclear Power Reactors 2.2.2 Charge Distribution Direct information on the distribution of yields along any given chain is confined to the relatively few good measurements of independent fission yields of individual chain members and of the shielded nuclides. An hypothesis which appears to account fairly well for most of the data is the postulate of “equal charge displacement.” To state this, we make use of the quantity ZA, the value of Z corresponding to the highest binding energy for a given A. Furthermore, we define Zp as the most probable charge for a primary fission fragment of mass number A. The postulate of equal charge displacement is that the two complementary fragments in a given fission event always have equal ZA−Zp values and, furthermore, that the probability distribution around Zp is the same for all values of A. Remembering that on the average 2.5 neutrons are emitted per U-235 fission, we can write ZA−Zp=Z233.5-A−(92−Zp), or Zp=46+1/2 (ZA−Z233.5-A). From this formula and ZA, Zp can be calculated for any A. The measured independent yields indicate a probability distribution such that 50% of the total chain yield occurs for Z=Zp, about 25% each for Z=Zp±1, about 2% for Z=Zp±2, and much less for other Z values. The isobaric yield distribution around Zp appears to be Gaussian, and the postulate of a universal distribution in Z at all values of A is borne out by experiment, but not understood theoretically. As an example, the charge dispersion among products with A=93 from thermal-neutron fission of U-235 is shown in Table 2–1 and Figure 2–2. As can be seen in Figure 2–2, the fractional independent yield or relative probability P(Z) of formation of a product with atomic number Z is well-represented by a Gaussian curve,(3) in which P(Z) is the fractional independent yield of the fission product with atomic number Z, fo.e. is the odd-even effect factor, and C is nearly constant for all fission product mass chains. The fractional cumulative yield of a fission product with charge Z is given by:(4)

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Radiochemistry in Nuclear Power Reactors Table 2–1 BETA DECAY CHAIN FOR MASS NUMBER 93 (Yields are for thermal-neutron fission of U-235) Nuclide Fractional Independent Yield Cumulative Yield % Br-93 (0.81s) 4.9×10–4 0.003 Kr-93 (1.3s) 0.075 0.49 Rb-93 (5.8s) 0.48 3.54 Sr-93 (7.5m) 0.39 6.21 Y-93 (10.2h) 0.19 6.37 Zr-93 (9.5×105y) 2×10–4 6.37 Nb-93 (Stable) 27×10−9 6.37 Figure 2–2. Charge Dispersion for Products with A=93 from Thermal-Neutron Fission of U-235

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Radiochemistry in Nuclear Power Reactors The value of C is related to the Gaussian curve width parameter (σ) which is nearly constant (σ=0.56) for all masses.*(5) Zp for each mass chain has been empirically determined based on many values of Zp found experimentally. Based on the charge distribution probability, Rider(6) has calculated by both the independent and cumulative fission yields for all fission products from various fission reactions. A summary of major fission product yields in thermal-neutron fission of U-235 and Pu-239 is given in Table 2–2. 2.3 TRANSURANIC NUCLIDES The transuranic elements are those produced by successive neutron capture of uranium and its products in a reactor. The chain of production and the radiation characteristic of each isotope are shown in Figure 2–3. In this production chain, the major products are: Neptunium −237, −239; Plutonium −238, −239, −240, −241, −242; Americium −241, 243; Curium −242; −244. Except for Np-239 and Pu-241, all the isotopes above are alpha emitters. Np-239 is a beta emitter and decays to Pu-239 with 2.36-day half-life. Pu-241 is also a beta emitter and decays to Am-241 with a 14.4-year half-life. A small fraction (0.0023%) of Pu-241 also decays to U-237 by emitting alpha particles. Experimental measurements, as well as theoretical calculations of each transuranic isotope buildup in the fuel element as a function of fuel burnup, have been reported by several investigators(8,9,10) for various fuel materials. Variations of transuranic isotope content with fuel burnup relative to total uranium are shown in Figure 2–4 for 2.5% enriched UO2 fuel. The transuranic activity buildup varies quite rapidly with the fuel burnup; however, the predominant alpha activity at the end of irradiation is Cm-242 (90 to 95%) because of its shorter half-life. As the fuel exposure increases, the fissionable nuclides (Pu-239 and Pu-241) are created in the fuel, and a large fraction of fission may be attributed to plutonium isotopes near the end of fuel life (Figure 2–5). *   C≈(σ2+1/12)

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Radiochemistry in Nuclear Power Reactors Table 2–2 CUMULATIVE YIELDS OF MAJOR FISSION PRODUCTS IN THERMAL NEUTRON FISSION OF U-235 AND Pu-239 Nuclide Half-life Decay constant λ, l/s Fission yields(Y), % Y*λ U-235 Pu-239 U-235 (U+Pu)/2 Br-84 31.80 m 3.63E-04 0.967 0.444 0.706 3.51E-06 2.56E-06 Kr-85m 4.48 h 4.30E-05 1.300 0.565 0.933 5.59E-07 4.01E-07 Kr-85 10.72 y 2.05E-09 0.285 0.128 0.207 5.86E-12 4.24E-12 Kr-87 1.37 h 1.41E-04 2.520 0.990 1.755 3.54E-06 2.47E-06 Kr-88 2.84 h 6.78E-05 3.550 1.320 2.435 2.41E-06 1.65E-06 Kr-89 3.15 m 3.67E-03 4.600 1.440 3.020 1.69E-04 1.11E-04 Kr-90 32.30 s 2.15E-02 4.860 1.400 3.130 1.04E-03 6.72E-04 Rb-88 17.70 m 6.53E-04 3.570 1.360 2.465 2.33E-05 1.61E-05 Rb-89 15.40 m 7.50E-04 4.770 1.680 3.225 3.58E-05 2.42E-05 Rb-90 2.60 m 4.44E-03 4.500 1.390 2.945 2.00E-04 1.31E-04 Rb-90m 4.30 m 2.69E-03 1.240 0.680 0.960 3.33E-05 2.58E-05 Rb-91 58.00 s 1.19E-02 5.670 2.160 3.915 6.77E-04 4.67E-04 Sr-89 50.50 d 1.59E-07 4.780 1.690 3.235 7.59E-09 5.14E-09 Sr-90 29.10 y 7.55E-10 5.910 2.110 4.010 4.46E-11 3.03E-11 Sr-91 9.51 h 1.93E-04 5.930 2.490 4.210 1.14E-05 8.11E-06 Sr-92 2.71 h 7.10E-05 5.910 3.040 4.475 4.20E-06 3.18E-06 Sr-93 7.40 m 1.56E-03 6.370 3.920 5.145 9.94E-05 8.03E-05 Y-90 2.67 d 3.00E-06 5.920 2.110 4.015 1.78E-07 1.21E-07 Y-91 58.50 d 1.37E-07 5.930 2.490 4.210 8.13E-09 5.77E-09 Y-92 3.54 h 5.44E-05 5.980 3.060 4.520 3.25E-06 2.46E-06 Y-93 10.20 h 1.89E-05 6.370 3.920 5.145 1.20E-06 9.71E-07 Zr-95 64.00 d 1.25E-07 6.490 4.890 5.690 8.14E-09 7.13E-09 Zr-97 16.80 h 1.15E-05 5.930 5.320 5.625 6.80E-07 6.45E-07 Nb-95 34.97 d 2.29E-07 6.490 4.890 5.690 1.49E-08 1.31E-08 Nb-97 1.23 h 1.57E-04 5.950 5.370 5.660 9.31E-06 8.86E-06 Mo-99 2.79 d 2.88E-06 6.120 6.160 6.140 1.76E-07 1.77E-07 Mo-101 14.60 m 7.91E-04 5.180 5.940 5.560 4.10E-05 4.40E-05 Tc-98m 6.02 h 3.20E-05 5.380 5.420 5.400 1.72E-06 1.73E-06 Tc-101 14.20 m 8.14E-04 5.180 5.950 5.565 4.21E-05 4.53E-05 Tc-104 18.00 m 6.42E-04 1.920 5.960 3.940 1.23E-05 2.53E-05 Ru-103 39.27 d 2.04E-07 3.040 6.950 4.995 6.21E-09 1.02E-08 Ru-105 4.44 h 4.34E-05 0.972 5.360 3.166 4.22E-07 1.37E-06 Ru-106 1.02 y 2.15E-08 0.403 4.280 2.342 8.68E-11 5.05E-10 Rh-105 35.40 h 5.44E-06 0.972 5.360 3.166 5.29E-08 1.72E-07 Sb-125 2.76 y 7.96E-09 0.029 0.115 0.072 2.31E-12 5.73E-12 Te-129m 33.60 d 2.39E-07 0.127 0.270 0.199 3.03E-10 4.74E-10 Te-132 3.26 d 2.46E-06 4.280 5.230 4.755 1.05E-07 1.17E-07 I-131 8.04 d 9.98E-07 2.880 3.850 3.365 2.87E-08 3.36E-08 I-132 2.28 h 8.44E-05 4.320 5.390 4.855 3.65E-06 4.10E-06 I-133 20.80 h 9.26E-06 6.690 6.930 6.810 6.19E-07 6.30E-07 I-134 52.60 m 2.20E-04 7.710 7.270 7.490 1.69E-05 1.65E-05 I-135 6.57 h 2.93E-05 6.300 6.450 6.375 1.85E-06 1.87E-06 I-136 1.39 m 8.31E-03 2.970 1.740 2.355 2.47E-04 1.96E-04

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Radiochemistry in Nuclear Power Reactors Nuclide Half-life Decay constant λ, l/s Fission yields(Y), % Y*λ U-235 Pu-239 U-235 (U+Pu)/2 Xe-133 5.24 d 1.53E-06 6.700 6.980 6.840 1.03E-07 1.05E-07 Xe-133m 2.23 d 3.60E-06 0.189 0.232 0.211 6.80E-09 7.57E-09 Xe-135m 15.30 m 7.55E-04 1.000 1.680 1.340 7.55E-06 1.01E-05 Xe-135 9.10 h 2.12E-05 6.540 7.600 7.070 1.38E-06 1.50E-06 Xe-137 3.82 m 3.02E-03 6.060 6.040 6.050 1.83E-04 1.83E-04 Xe-138 14.20 m 8.14E-04 6.420 5.120 5.770 5.22E-05 4.69E-05 Xe-139 39.70 s 1.75E-02 5.040 3.050 4.045 8.80E-04 7.06E-04 Xe-140 13.70 s 5.06E-02 3.620 1.600 2.610 1.83E-03 1.32E-03 Cs-137 30.17 y 7.29E-10 6.220 6.690 6.455 4.53E-11 4.70E-11 Cs-138 32.20 m 3.59E-04 6.640 5.910 6.275 2.38E-05 2.25E-05 Cs-139 9.30 m 1.24E-03 6.280 5.350 5.815 7.80E-05 7.22E-05 Ba-139 83.70 m 1.38E-04 6.350 5.600 5.975 8.76E-06 8.25E-06 Ba-140 12.75 d 6.29E-07 6.270 5.540 5.905 3.95E-08 3.72E-08 Ba-141 18.30 m 6.31E-04 5.790 5.230 5.510 3.66E-05 3.48E-05 Ba-142 10.70 m 1.08E-03 5.730 4.600 5.165 6.19E-05 5.58E-05 La-140 40.27 h 4.78E-06 6.280 5.550 5.915 3.00E-07 2.83E-07 La-141 3.90 h 4.94E-05 5.810 5.310 5.560 2.87E-06 2.74E-06 La-142 92.50 m 1.25E-04 5.830 4.910 5.370 7.28E-06 6.71E-06 Ce-141 32.50 d 2.47E-07 5.800 5.260 5.530 1.43E-08 1.37E-08 Ce-143 33.00 h 5.83E-06 5.940 4.430 5.185 3.47E-07 3.03E-07 Ce-144 284.60 d 2.82E-08 5.470 3.740 4.605 1.54E-09 1.30E-09 Nd-147 10.99 d 7.30E-07 2.250 2.040 2.145 1.64E-08 1.57E-08 Np-239 2.35 d 3.41E-06 60.000 60.000 60.000 2.05E-06 2.05E-06

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Radiochemistry in Nuclear Power Reactors Figure 2–3. Actinide Chains in Uranium-Plutonium Fuel (Reproduced with Permission, from Ann. Rev. Nucl. Sci., Ref. 7)

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Radiochemistry in Nuclear Power Reactors Figure 2–4. Variation of Transuranic Isotope Content with Fuel Exposure in UO2 Fuel

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Radiochemistry in Nuclear Power Reactors Figure 2–5. Variation of Fractional Fissions from Fissionable Nuclides in UO2 Fuel (2.5% U-235) with Fuel Exposure

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Radiochemistry in Nuclear Power Reactors 2.4 ACTIVATION OF WATER AND IMPURITIES IN REACTOR COOLANT Water and impurities in water are activated only when the water flows through the core region; the residence time in the flux zone is only a few seconds for each path. The relevant nuclear data for major activation products in the BWR coolant are given in Table 2–3. Among these nuclides, N-16 (t1/2=7.1 s) is probably the most important nuclide because of its high-energy gamma ray (6.1 MeV) where the radiological effect is concerned. The chemistry and transport behavior of N-16 and other semi-volatile species in the BWR primary system will be discussed later (Subsection 5.4). The production rates of radioactive species in water depend on the concentrations of their parent targets in water. The equilibrium concentration of a radioactive nuclide can be estimated as follows: (2–3) where No=number of parent target atoms N=number of activation product atoms n=parent target input rate, atom/s λ=decay constant, s−1 βc=reactor water cleanup time constant, s−1. = P=reactor power and core geometric factor =effective neutron flux for target activation σ=effective activation cross section

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Radiochemistry in Nuclear Power Reactors Table 2–3 MAJOR WATER AND IMPURITY ACTIVATION PRODUCTS IN REACTOR COOLANT Nuclide Half-Life Reaction Natural Isotopic Abundance (%) Average Activation Cross Sectiona 3H 12.3 y 2H(n,α)3H 0.015 0.53 mb(T)     6Li(n,α)3H 7.5 942 b (F)     10B(n,2α)3H — 5.6 mb (F)     10B(n,α)7Li — 3838 b (F)     235U(n,f)3H — 0.01% fy 14C 5730 y 13C(n,γ)14C 1.11 0.9 mb (T)b     14N(n,p)14C 99.63 1.8 b (F)b     17O(n,α)14C 0.038 240 mb (F)b 15C 2.45 s 18O(n,α)15C 0.204 1.5 mb (F) 13N 9.97 m 16O(p,α)13N 99.76 50 mb (P)c 16N 7.13 s 16O(n,p)16N 99.76 19 mb (F) 19O 26.9 s 18O(n,γ)19O 0.204 160 mb (T) 18F 1.83 h 18O(p,n)18F 0.204 300 mb (P) 24Na 14.96 h 23Na(n,γ)24N 100 528 mb (T) 32P 14.28 d 31P(n,γ)32P 100 190 mb (T)     32S(n,p)32P 95 69 mb (F) 38Cl 37.2 m 37Cl(n,γ)38Cl 24.23 430 mb (T) (a) Data for 20°C; T, F, and P in the parentheses indicate thermal and fast neutron and proton reactions, respectively; the activation cross-section data are adopted from References 1 and 2. (b) P.J.Magno, et al, Proc. 13th AEC Air Cleaning Conf., P1047 (1972). (c) M.S.Singh and L.Ruby, Nucl. Tech., 17, 104 (1973).

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Radiochemistry in Nuclear Power Reactors At equilibrium condition during normal operation, (2–4) Thus, by measuring Neq and P can be calculated. For the parent nuclide, (2–5) At equilibrium, (2–6) Thus, the total active impurity at equilibrium condition can be estimated by: (2–7) The core average neutron flux in a light water reactor may be approximately related to the power density of the core. For a BWR with the core power density at 50 W/cm3, the average fluxes for thermal, epithermal and fast neutrons in the core region are estimated at 1.35×1014, 6×1013 and 3.9×1013 n/cm2/s, respectively.

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Radiochemistry in Nuclear Power Reactors 2.5 ACTIVATION OF CORROSION PRODUCTS The metallic impurities are released into the coolant from the struc-tural materials in the feedwater and primary systems as a result of corrosion/erosion. When they are deposited on the fuel surfaces, they become activated by the neutron flux in the core. Some activation products are also produced in the structural materials in the core. The pertinent nuclear data for the major activated corrosion products are given in Table 2–4. The activity (A) produced in the structural material in the core region at time to can be calculated by (2–8) All symbols have the meanings given previously. The calculated specific activities as a function of irradiation time at a constant neutron flux for the major activation products generally found in lightwater reactors are shown in Figure 2–6. The calculation of activity production in the fuel deposit is rather complex; it involves variations in corrosion product deposition rate, neutron flux, release of activities, etc. The details of model calculations are discussed and compared with the experimental data in Section 4.

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Radiochemistry in Nuclear Power Reactors Table 2–4 MAJOR ACTIVATED CORROSION PRODUCTS IN LIGHT WATER REACTORS Nuclide Half-Life Formation Reaction Nature Isotopic Abundance (%) Activation Cross Section (Barns)a Thermal Epithermal Fast 51Cr 27.7 d 50Cr(n,γ)51Cr 4.35 16.0 0.68   54Mn 312.2 d 54Fe(n,p)54Mn 5.8     0.11 56Mn 2.58 h 55Mn(n,γ)56Mn 100 13.3 1.13   55Fe 2.73 y 54Fe(n,γ)55Fe 5.8 2.5 0.1   59Fe 44.51 d 58Fe(n,γ)59Fe 0.3 1.14 0.1   58Co 70.88 d 58Ni(n,p)58Cob 68.3     0.146 60Co 5.27 y 59Co(n,γ)60Co 100 37.5 6.05   63Ni 100 y 62Ni(n,γ)63Ni 3.6 14.6 0.77   65Ni 2.52 h 64Ni(n,γ)65Ni 0.9 1.50 0.07   64Cu 12.7 h 63Cu(n,γ)64Cu 69.2 4.4 0.40   65Zn 243.8 d 64Zn(n,γ)65Zn 48.6 0.82 0.13   76As 26.3 h 75As(n,γ)76As 100 4.4 5.08   95Zr 64.02 d 94Zr(n,γ)95Zr 17.4 0.075 0.031   110mAg 249.8 d 109Ag(n,γ)110mAg 48.17 4.7     113Sn 115.1 d 112Sn(n,γ)113Sn 1.01 0.71 2.2   124Sb 60.2 d 123Sb(n,γ)124Sb 42.7 4.0 9.7   181Hf 42.4 d 180Hf(n,γ)181Hf 35.2 12.6 2.26   182Ta 114.43 d 181Ta(n,γ)182Ta 100 22.0 56.4   187W 23.9 h 186W(n,γ)187W 28.6 37.2 33.9   aData for 20°C. bBurnup cross section, σb, for Co-58 is 1.9×10−21 cm2.

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Radiochemistry in Nuclear Power Reactors Figure 2–6. Specific Activity of Major Corrosion Products as a Function of Irradiation Time with Neutron Flux

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Radiochemistry in Nuclear Power Reactors 2.6 REFERENCES (1) C.M.Lederer et al., “Table of Isotopes,” 7th ed., John Wiley & Sons, Inc., New York (1978). (2) “Handbook on Nuclear Activation Cross Sections,” Technical Report Series No. 156, IAEA, Vienna (1974). (3) A.C.Wahl, “Mass and Charge Distribution in Low-Energy Fission,” Proc. 1st International Atomic Energy Symposium on Physics and Chemistry of Fission, Vienna, Austria (IAEA, 1965). (4) B.Ehrenberg and S.Amiel, Phys., Rev. C, 6, p. 618 (1972). (5) A.C.Wahl et al., Proc. 2nd International Atomic Energy Symposium on Physics and Chemistry of Fission, Vienna, Austria, p. 813 (IAEA, 1969). (6) B.F.Rider, “Compilation of Fission Product Yields,” Vallecitos Nuclear Center, 1981 (NEDO-12154–3C), ENDF-322 (October 1981). (7) T.H.Pigford, “Environmental Aspects of Nuclear Energy Production,” Am. Rev. Nucl. Sci., Vol. 24, 1974, p. 515. (8) H.S.Bailey, et al., Nucl. Tech., 17, 1973, p. 217. (9) H.Umezawa, et al., J. Nucl. Sci. Tech., 10, 1973, p. 489. (10) W.B.Wilson, et al., Nucl. Safety, 29, 2, 177 (1988). 2.7 BIBLIOGRAPHY G.Friedlander, J.W.Kennedy, E.S.Macias and J.M.Miller, “Nuclear and Radiochemistry,” 3rd ed., John Wiley & Sons, Inc., New York (1981). D.C.Layman and G.Thorton, “Remote Handling of Mobile Nuclear Systems,” U.S. AEC, January 1966 (TID-21719).