Reactivity effects (autocatalysis) in BR-1 and BR-K1 pulsed reactors
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Manifestations of autocatalysis, caused by neutron-absorbing samples loaded into a cavity in the core, in explosive accidents in BR-1 and BR-K1 reactors were investigated. The investigation was conducted on the basis of calculations using a multigroup neutron-gas-dynamic program for one-dimensional calculations of fission surges in various configurations of the reactors indicated. It was shown that, even though the boron content in the screens is comparatively limited and the natural isotopic composition of boron is used in the BR-K1 screen, in the case of accidents accompanied by a chain reaction of an explosive type strong manifestations of autocatalysis with nine-fold (BR-1) and 520-fold (BR-K1) increase of energy release in accidental surges are possible.
However, the analysis also showed that the manifestations of autocatalysis on this scale are possible only if large excess margins of reactivity are present in the reactors. In BR-1 and BR-K1 reactors, where the margin of reactivity is limited, only moderate manifestations of autocatalysis with a 1.5-fold (BR-1) and 4-fold (BR-K1) increase of energy release in a surge can be observed in reality.
The indicated manifestations of autocatalysis in BR-1 and BR-K1 reactors do not require a re-examination of the categories of danger for these reactors, but they must be taken into account during reactor operation. The prohibition of any changes in the reactor configurations which can increase the margin of reactivity must be carefully followed.
We thank L. A. Kuz'min for assisting in the calculations and S. V. Petrin for providing the data on the characteristics of accident situations in BR-1 and BR-K1 reactors and for a fruitful discussion of the results obtained in this work.
KeywordsBoron Explosive Isotopic Composition Energy Release Boron Content
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- 1.R. Nicholson, “Methods for determining the energy release in a hypothetical fast reactor of meltdown accidents,”Nucl. Sci. Eng.,18, No. 2, 207–219 (1964).Google Scholar
- 2.G. Hummel and D. Okrent,Reactivity Coefficients in Large Fast Power Reactors [in Russia], Atomizdat, Moscow (1975), p. 237.Google Scholar
- 3.D. Hetrick, “Computer simulation of hypothetical criticality accidents in aqueous fissile solutions,”Trans. Am. Nucl. Soc.,63, No. 1, 226–228 (1991).Google Scholar
- 4.I. Pazsit, “Comment on the modeling of thin absorbers via δ functions,”Nucl. Sci. Eng.,116, No. 3, 223–225 (1994).Google Scholar
- 5.V. F. Kolesov, V. S. Bosamykin, V. Kh. Khoruzhii, and V. F. Yudintsev, “Nuclear safety of critical assemblies with neutron absorber in a cavity,” At. Énerg.,83, No. 2, 105–112 (1997).Google Scholar
- 7.Yu. B. Khariton, A. M. Voinov, V. F. Kolesov, et al., “Aperiodic research pulsed reactors”, in:Problems of Modern Experimental and Theoretical Physics [in Russian], Nauka, Leningrad (1984), pp. 103–119.Google Scholar
- 8.Yu. B. Khariton, A. M. Voinov, V. F. Kolesov, et al., “Pulsed reactors at All-Russia Scientific-Research Institute of Experimental Physics (review),”Voprosy Atomnoi Nauki i Tekhniki, Ser. Fiz. Yadernykh Reaktorov, No. 2 3–12 (1985).Google Scholar
- 9.A. I. Pavlovskii, A. A. Malinnkin, V. F. Kolesov, et al., “BR-1 booster reactor,” ibid., No. 1, 3–13 (1985).Google Scholar
- 10.V. S. Bodamykin, A. A. Malinkin, V. F. Kolesov et al., “Construction and physicotechnical characteristics of the BR-K1 booster reactor,” ibid., No. 1, 3–13 (1996).Google Scholar