Sensitivity of reactivity insertion limits with respect to safety parameters in a typical MTR

Lumped parameters analysis of coupled kinetics and thermal-hydraulics for small reactors

“…Full details on the reactor description can be found in Housiadas (2000). The results of Table 2 indicate that the lumped parameters model Table 2 Comparison between the predictions obtained with the proposed lumped parameters model and the code generated results (in parentheses) of Nasir et al (1999) provides quite accurate predictions for the peak points of power and core temperature for reactivity insertions up $1.5. At larger reactivity insertions the model performances deteriorate rapidly, and unrealistic results are provided.…”

“…To assess the capabilities of the model presented above, we reproduced relevant transient cases that were analysed recently in the literature (Mirza et al, 1998;Nasir et al, 1999). In these works, unprotected (without scram) reactivity insertion transients in typical pool-type research reactors were analysed with the help of the code PARET.…”

“…To determine the validity range of the model we compared the model predictions with the sensitivity analysis results of Nasir et al (1999). The latter used the code PARET to investigate the response of a research reactor to various ramp reactivity insertion conditions.…”

“…The comparison is provided in Table 2 in terms of peak power and maximum coolant and fuel temperatures attained, together with the times to reach peak conditions. As before, the required input data were taken from the paper of Nasir et al (1999) (see Table 1). Since the paper does not document results for ramp reactivity insertions less than $1.5/0.5 s, we performed some supplementary PARET simulations (cases of Table 2 marked with an asterisk).…”

“…The analysis of the transient behaviour of research reactors has received prompt (Woodruff, 1984), as well as recent attention (Mirza et al, 1998;Nasir et al, 1999;Housiadas, 2000) because of its relevance in determining the limits imposed by clad melting temperature. As a rule, the analysis of such transients is carried out with the help of large code systems that simulate the coupled kinetics and thermal-hydraulics of the reactor core.…”