Three-dimensional diffusion theory model of Chernobyl-4

Conference · Thu Jan 01 04:00:00 EST 1987 · Trans. Am. Nucl. Soc.; (United States)

OSTI ID:5746034

Heeb, C M; Lotz, T L; Doherty, A L

A three-dimensional neutron diffusion theory model of the Chernobyl-4 RBMK reactor was developed to analyze the April 26, 1986, accident. The model provides a means to determine the reactivity worths of key reactor systems such as control rods and reactor coolant condition, as well as power distributions at various times during the accident scenario. Hence it is useful in evaluating proposed corrective action by the USSR. Initial applications of the model have focused on the scram rod worths as a function of insertion and the reactivity effect of increasing core steam void fraction. The model uses neutron diffusion theory in two energy groups. The 2-group spectrum-average macroscopic cross sections were calculated using the WIMS code. The Winfrith improved multigroup scheme was used. The cell spectrum calculation employed 69 energy groups, which were ultimately collapsed to the 2-group set used in the model. The 2-group macroscopic cross sections are dependent on fuel burnup, fuel temperature, and water density. Each node in the model can have different macroscopic cross-section values, which depend on nodal values of these three variables. Fuel channel water density calculations include the effects of subcooled as well as saturated coolant boiling. Fuel temperatures are also calculated for each fuel node. The model also contains nodal /sup 135/Xe feedback.

• Research Organization: Pacific Northwest Labs., Richland, WA
• OSTI ID: 5746034
• Report Number(s): CONF-870601-
• Conference Information: Journal Name: Trans. Am. Nucl. Soc.; (United States) Journal Volume: 54
• Country of Publication: United States
• Language: English

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