A new model for the dynamic of criticality excursions in fissile solutions - 14446
- Millennium, a Nuvia Company, 16 avenue du Quebec, bat. Lys 91945 Villebon-sur-Yvette (France)
A recent international inter-code comparison exercise for criticality excursion analysis demonstrated that the transient criticality codes participating the exercise are showed to reproduce well the initial peak power compared with measurements performed with TRACY and SILENE reactors. However the oscillatory behavior after peak power is less well reproduced. The integrated behavior in term of energy release is quite well reproduced. The recent experiments performed with TRACY JAEA's reactor and the analytic interpretation of void clustering during prompt critical have suggested a simplified vibration model of a damped oscillator. Finally a recent ICNC paper by present authors offered a perfect correlation between peak pressure and peak power. Owing to these three facts the present paper aims at proposing a new system of equations for the dynamic of a critical excursion taking into account gas bubble generation after exceeding the solubility threshold of dissolved radiolytic gas. The model explains why the simple vibration model of the JAEA school fairly represent pressure dynamic records at moderate peak pressure as measured with SILENE reactor. Also, an important parameter of the proposed model, namely the rate of transfer from dissolved gas to gas bubbles, is fixed by the correlation between peak pressure and peak power. Thus the model has one less tunable parameter and can predict a large range of critical low pressure excursions. After presentation of the model and discussion of some of its important features, some numerical simulations are made based upon SILENE and TRACY transient experiments ranging from tenths of kPa to several bars and comparisons are presented between calculated results and experimentally recorded one's. (authors)
- Research Organization:
- American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 23100897
- Resource Relation:
- Conference: ICNC 2015: 2015 International Conference on Nuclear Criticality Safety, Charlotte, NC (United States), 13-17 Sep 2015; Other Information: Country of input: France; 6 refs.; available on CD Rom from American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (US)
- Country of Publication:
- United States
- Language:
- English
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