“…It is also one of the most challenging problems in nuclear reactor engineering, and has not been solved well yet, Gong et al (2011). There are many optimization methods and papers about LPO during recent years, such as ant colony algorithm (Machado and Schirru, 2002), artificial intelligence techniques like artificial neural networks (Sadighi et al, 2002), genetic algorithms (Mohseni et al, 2008), discrete particle swarm optimization (Babazadeh et al, 2009), continuous particle swarm optimization (Meneses et al, 2009;Babazadeh et al, 2009), improved pivot particle swarm method (Liu and Cai, 2012), interval bound algorithm (Gong et al, 2011), harmony search algorithm (Poursalehi et al, 2013a), continuous firefly algorithm (Poursalehi et al, 2013b), discrete firefly algorithm (Poursalehi et al, 2013c), bat algorithm (Kashi et al, 2014) and etc.…”