• Erez Gilad

PUBLISHED: How to accurately evaluate the readioactivity in the core?

Nuclear constitutes an essential energy resource in many countries worldwide, as it is a key contributor to reliable, safe, and clean (zero-emission) electricity supply during the Covid pandemic.

The state of Israel is interested in adding nuclear energy to its future mix of energy resources. In particular, the main interest is in an innovative nuclear reactor design, the Small Modular Reactor (SMR). This reactor type is of great interest to the international nuclear community thanks to its enhanced safety, economic competitiveness, and short constructiontime.

Nevertheless, a nuclear power plant in Israel will be considered a strategic facility, and its destruction due to terror attacks or war activities is a scenario that must be considered. This threat is unique to the state of Israel and comprises many accurate rockets covering the entire area of Israel.

Accurate simulation models of the radioactive nuclide inventory in the reactor core provide the necessary data for risk analysis and evaluation of exposure hazards to the public. Public health is in interest, especially in postulated accidental releases of radioactive materials to the atmosphere.

Our newly published paper aims to provide a novel view and deeper physical insight into the numerical consequences of deviation from Critical Boron Concentration (CBC) during the burnup of the SMR fuel, affecting the evaluation of the radioactive inventory. Soluble boron is used in many commercial reactors to reach criticality, where a nuclear facility is maintained under control by the reactor operators. The paper is entitle "Study of radionuclide inventory in nuclear fuel under uncertainties in boron concentration using high-fidelity models", and was revently published in International Journal of Energy Research, DOI:10.1002/er.7702 [LINK] [PDF].

The results of our research indicate that deviation from the critical boron concentration during calculation may lead to significant discrepancies in nuclide densities during the irradiation cycle, which tends to decrease towards the end of the cycle. The physical processes underlying this behavior are studied in depth using a high-fidelity model and Monte Carlo transport calculations with the Serpent code. The methodology presented in this study may be used for systematic uncertainty and sensitivity analysis to optimize and perform the best estimation of the consequences of an accidental release of radioactive material to the atmosphere.

Dr. Christian Castagna, first author of the paper.

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