Fission product yields

Meek, M. E. and Rider, B. F. (1974). Compilation of Fission Product Yields, Vallecitos Nuclear Center, 1974, General Electric Report No. NEDO-12154-1 (General Electric Company, Vallecitos Nuclear Center, Pleasanton, California). 

Zysin, Y. A., Fission Product Yields and Their Mass Distribution, p. 63,... 

Evaluation and Compilation of Fission Product Yields 1993, T,R. England and B,F. Rider Rept. LA-UR-94-3106 (1994), ENDF/B-VI evaluation MAT 9228, Revision 1,... 

Crouch, E.A.C. (1977) Fission product yields from neutron-induced fission. Atomic Data Nuclear Data Tables, 19,417-532. 

The mass spectrometric method of fission product yield measurements can be applied to the entire mass range of fission products. Inghram et al. (55) investigated fission products in the rare earth region and showed how the partial yield curves obtained from isotope abundance measurements for the various elements can be fitted together by the method of stable... 

England, T. R. and Rider, B. F. 1994. Evaluation and compilation of fission product yields 1993. Los Alamos National Laboratory Report LA-UR-94-3106. ENDF (Evaluated Nuclear Data File) 349. Viewed on January, 2006. 

U.S. Air Force, Fission Product Yield Release Test 1, Rep. NARF-59-32T (1959). 

In addition, the physical measurements (after some corrections for prompt neutron emission) allow one to obtain fragment mass distributions (prior to prompt neutron emission). A comparison of these fission fragment yield curves with fission product yield curves makes it possible to extract information on prompt neutron emission. This will be discussed in the next subsection. 

Fission fragments (pre-neutron emission). The yield curves discussed above refer to fission product yields after emission of prompt neutrons. As discussed above, the physical methods based on momentum conservation at scission (double energy, double velocity, or energy and velocity measurements) allow the measurement of the yield distribution of fission fragments (prior to prompt neutron emission). In these cases, simultaneous information is obtained on the kinetic energy of the fragments detected. 

O Table 56.7 lists independent fission product yields (England and Rider 1994) per 100 fissions for the most important fissionable nuclides. For thermal, fast neutron (fission spectrum), and high-energy neutron (14 MeV) induced, for fast neutron induced,... 

The advantage of this technique is that it does not require a double fission-chamber calibration as in the gross fission-product counting technique, or elaborate chemistry and reliance upon fission-product yields as required in the method that separates and counts a single fission product. 

For the purpose of determining off-site effects of criticality accidents it has been normal practice to postulate accliients in various configurations and media within a plant. Foir My specific proposed accident it is the fission energy estimate, that ultimately determines the dose at the boundary since all other factors, i.e., fission-product yields, decay rates, dilution effect, breathing rates, plateoul, etc., involved in the dose estimate are relatively weil understood. 

Fission product yields from fast neutron fission show a very similar distribution to Figure 1.29, the main difference being that yields in the minimum between the two peaks increase by a factor of about three. 

In 1937 Perrier and Segre bombarded a molybdenum target with deuterons to produce technetium as the first man-made element [34]. This element has 31 known isotopes with mass numbers firom 86 to 117, and all are radioactive. The most readily available isotope is Tc = 2.1 X10 years), which can be isolated from spent nuclear fuel where it constitutes approximately 6% of the fission product yield of U. In the recovery process, the pertechnetate anion, [ TcO, ] , is extracted with pyridine firom aqueous solution and ultimately isolated as [NH j [TcO, ] with a purity of better than 99.9% [35]. The ammonium salt is readily available at a reasonable cost from Oak Ridge National Laboratory [36]. 

Xenon balance in the reactor is illustrated in Figure 8.1. Since iodine-135 decays to become xenon-135, its balance in the reactor must also be considered, Iodine-135 is formed by decay of tellurium-135 and as a fission product and, in turn, decays to become xenon 135. The half life of tellurium-135 is 19 seconds in comparison to 6.7 hours for iodine-135, For all practical purposes it can be assumed that all iodine-135 is formed directly by fission, For this reason a fission product yield fraction for iodine-135, Vt, is given in Table 8,2 when tellurium-135 is, in fact, the fission product. Tables 6.2 and 8.3 provide fission product yields, half-lives, and decay constants for those isotopes involved with fission product poisoning. 

Table 8.P Fission Product Yields in Atoms per Fission for I135(yj), Xe(Yj ), and Pml49(Yp) from Thermal...

Measurements of fission product yields and decay properties are made, for example at the reactor of the Studsvik Neutron Research Laboratory of the University of Uppsala, in Sweden. This has a facility called OSIRIS for the rapid transfer and analysis of irradiated samples. 

An evaluation of the available measured nuclear data is necessaiy to produce a recommended file of cross-section data for a nuclide, or an evaluation of fission product yields or the radioactive decay data for a nuclide. This is because there are often several sets of measurements or gaps in the measured data which must be filled using theory. Inconsistent data must be examined and a best estimate made, taking into accoimt any theoretical constraints. There are several evaluation projects which coordinate the efforts of the scientists working in the field and make plans to meet the data requirements. All cross-section... 

E. A. C. Crouch, Fission-Product Yields from Neutron-Induced Fission, Atomic Data and Nuclear Data Tables 19, 417-432, Academic Press, New York (1977). 

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