Iodine spike

In this method lg of soil is refluxed with 2M sodium hydroxide after centrifuging to remove solids. The clean extract is digested with perchloric acid-nitric acid at 265 °C. The iodine content of the extract is determined by the catalytic action of iodine on the oxidation of arsenic III ions with cerium IV ions. Between 96 and 97% recovery of added iodine spikes to soil were obtained by this method. 

We further assessed the extraction recovery of different iodine species in a KCl extractant (Table 10.4). Two concentrations (either 0.091 or 0.91 mg/1) of iodine spike species were used. In the mixed iodine treatment, a mixture of iodide, iodate, and 4-iodoaniline (each with a concentration of either 0.091 or 0.91 mg/1) was spiked into SRM 2709. It appears, for iodide and iodate, the lower spike concentration produced a recovery of >100% this is likely related to the larger analytical uncertainty at lower... 

For iodine-131 (the same considerations are valid for caesium), the effects of the phenomenon of iodine spike are, in addition, taken into consideration (this is an increase in the release of these radioactive products from the fissured fuel rods caused by power variations). The phenomena involved are connected with the ingress and subsequent exit of water through the gap and with likely fracturing of the fuel matrix. Guidance on figures to be used can be found in USNRC (1996). The normal values are ... 

Iodine spiking in pressurized water reactors was first analyzed in detail by Neeb (1971) using data obtained by measurment during several reactor shutdowns at the Obrigheim PWR plant. The time-behavior of the activity concentrations of the iodine isotopes in the coolant, which is exemplarily shown in Fig. 4.9., is fully consistent with the results reported by other authors, e. g. by Chubb et al. (1977), from Westinghouse PWR plants. 

Adams, J. P., Atwood, C. L. The iodine spiking release rate during a steam generator tube rupture. Nucl. Technology 94, 361—371 (1991)... 

Beslu, P., Leuthrot, C., Brissaud, A., Harrer, A., Beuken, G. Solid fission products and actinides release and deposition inside PWR s primary circuits. Proc. 5. Intemat. Meeting on Thermal Nuclear Reactor Safety, Karlsruhe 1984, (KfK-3880) p. 1387-1397 Bishop, W. N. Iodine spiking. Report EPRI NP-4595 (1986)... 

Chubb, W., Piplica, E. J., Lutz, R. J. The iodine spiking phenomenon in pressurized water reactor coolants. Trans. Am. Nucl. Soc. 26, 517-518 (1977)... 

Neeb, K. H., Schuster, E. Iodine spiking in PWRs Origin and general behavior. Trans. Am. Nucl. Soc. 28, 650-651 (1978)... 

The rupture of a steam generator tube in a PWR can potentially lead to releases of radioactive substances to the atmosphere. These releases could be significant because, if iodine spiking does not occur immediately before the initiation of this event, it will occur during the course of the transient. Actual incidents of steam generator tube rupture have occurred in at least 12 operating nuclear power plants. 

In 1986, in-core sipping equipment designed and manufactured by Siemens KWU was purchased [22,23]. Since then, fiiU core sipping tests have been performed in all cases where the occurrence of a leak has been demonstrated by operational data. The decision to perform sipping tests was taken based on primary coolant activity measurements obtained during reactor operation and iodine spike analysis. 

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