Ambient office  = 89 nanosieverts per hour

Ambient outside = 150 nanosieverts per hour

Soil exposed to rain water = 154 nanosieverts per hour

Beefsteak tomato from Central Market = 67 nanosieverts per hour

Tap water = 56 nanosieverts per hour

Filter water = 52 nanosieverts per hour

Part 2 of 2 Parts (Please read Part 1 first)
      In their research, the authors developed improved crossover and mutation operators. An LP can be considered as a two-dimensional array containing materials of different types such as fuel, absorber and reflector. Each LP is represented by a “chromosome” whose “genes” represent the different locations and types of FAs in the core. The chromosome representation is chosen to be a permutation of the core structure. This is done in order to preserve the predetermined quantities of the different materials and elements in the core. This representation is selected because it gives researchers simple and intuitive physical meaning to the “genetic” variation of the of the population. Variations that are similar have similar LPs.
       Another contribution of the authors is that they are taking geometrical aspects into account by considering the physical spatial structure of the core. They have developed a new geometric crossover operator based on the layout of the core. Their tests indicate that this approach yields excellent results for optimization. Crossover is the genetic operator that is responsible for creating new entities based on two or more parents. The operator swaps gene segments between the parents to create offspring with a mixture of the parents’ genes. This done by swapping rectangular segments of neighboring FAs between two selected LP parents.
       The researchers from BGU also came up with highly adaptive mutation techniques. These are based on the instantaneous genetic variance of the population. The algorithm tracks the genetic diversity of the population in real time. Then it automatically alters the mutation rate based on the level of homogeneity of the population. As the population becomes more homogenous, the mutation rate is raised. This approach results in enhanced algorithmic performances.
       The BGU researchers challenge the traditional assumptions about symmetrical core design which have dominated the field of LP design up to this point. This assumption is based on the fact that the different primary coolant loops in the nuclear reactor have to maintain similar thermal-hydraulic conditions during normal operation. This imposes symmetry on the power distribution of the reactor core. Symmetrical LP designs are much more intuitive than other layouts and engineers who design nuclear reactors often include their intuitions and experiences in reactor core design. Such symmetry constraints are not necessarily honored in the design of research reactors and small modular reactors. The BGU researchers came to the conclusion that the best LPs are not necessarily symmetrical.
       This study was an excellent example of an interdisciplinary project. In order to carry it out, the researchers had to have major expertise in both GAs and nuclear reactor physics. This is obviously an important area of research, but it is just in the beginning stages. Any tool that improves the operation of nuclear power plants is certainly welcome as the nuclear industry competes with cheap natural gas and renewable sources with falling prices. Many nuclear reactors are in danger of being shut down because they are too uneconomical to maintain and operate.

Ambient office  = 89 nanosieverts per hour

Ambient outside = 150 nanosieverts per hour

Soil exposed to rain water = 154 nanosieverts per hour

Yam from Central Market = 67 nanosieverts per hour

Tap water = 56 nanosieverts per hour

Filter water = 52 nanosieverts per hour

Part 1 of 2 Parts
       Genetic algorithms (GA) are a type of computer software that utilize evolutionary processes imitating biology. A bunch of solutions to a problem are developed that are all slightly different from each other. Then they are set loose to solve the problem. A few of the best solutions are then used to create a new set of slightly different solutions. In some cases, two solutions are combined to make a new solution and then the process is run again. Through successive “generations”, better and better solutions are “evolved.”
       When nuclear fuel rod assemblies (FAs) are burned in a nuclear reactor core, they are not all consumed at the same rate. After eighteen to twenty-four months, the reactor is shut down and the reactor vessel is opened up to insert new FAs. This process is expensive and time consuming. Usually, about one third of the FAs that show the most depletion is replaced. The new assemblies and the two thirds of the assemblies that are left are rearranged to form a new configurations of FAs in the core. The arrangement of FAs is referred to as a “Loading Pattern” (LP). The new arrangement is supposed to satisfy several criteria but some of these are in conflict. Maximizing the production of energy might work against insuring safety regulations and operational constraints and visa versa.
       Figuring out the best arrangement of FAs to simultaneously satisfy the conflicting criterion is an example of what is called a “classical discrete optimization problem”. The search space of possible arrangements is huge. This is a multi-objective, nonlinear, nonconvex, NP-hard combinatorial problem. In a standard pressurized water reactor, the most common kind of commercial power reactor, there are about two hundred FAs. There are also about two hundred different possible ways to arrange those assemblies. These different LPs each have to be evaluated, analyzed and characterized using sophisticated computer simulation with complex calculations. Assuming that it takes one second to evaluate a single core, it would take about 10360 years to explore the entire search space of possible configurations. The current age of the universe is only about 1010 years. Obviously, a better and faster way is needed to evaluate possible core configurations.
       The genetic algorithms mentioned above are well-known methods of solving this type of optimization problem. They generate and evolve solutions to move through the huge search space of possible LPs to find the best one. Each LP is considered as an individual. Parent LPs are selected based on how well they fit the criterion and then they are mutated and recombined to create the next generation. After many generations, optimal LPs emerge from the process.
       Dr. Erez Gilad and Ph.D. candidate Ella Israli are researchers at the Unit of Nuclear Engineering at Ben-Gurion University of the Negev (BGU). They recently published a study in the Annals of Nuclear Energy on the use of GAs for optimizing core design in nuclear reactors. They mentioned some of the problems that can be found with some uses of the GAs. They said that many GAs studies use old and outmoded GA implementation. These might disregard important and critical information such as the geometric structure of the core. Another problem would be the imposing of symmetric restrictions just to reduce the runtime of the algorithm. In their report, the authors develop, implement and evaluation novel GA methods using different case studies of LP design.
Please read Part 2

Ambient office  = 89 nanosieverts per hour

Ambient outside = 150 nanosieverts per hour

Soil exposed to rain water = 154 nanosieverts per hour

Iceberg lettuce from Central Market = 67 nanosieverts per hour

Tap water = 56 nanosieverts per hour

Filter water = 52 nanosieverts per hour

       Saudi Arabia is accepting bids for the construction of multiple nuclear power reactors. Westinghouse, a U.S. company, is very interested in building those reactors but there are problems because some of the technologies involved have dual use. This means that they can be used for commercial nuclear power reactors and also can be used in the development of nuclear weapons. The U.S. has rules about who they can sell such technologies to and Saudi Arabia does not satisfy the criterion for such sales. U.S. official are working hard to figure out a way to get around these restrictions.
       Saudi Arabia has said that if Iran were to obtain nuclear weapons, then Saudi Arabia would need to develop nuclear weapons as well as a counter. There are reports that Saudi Arabia and Pakistan have an understanding that if Iran obtains nuclear weapons, Pakistan would ship nuclear weapons to Saudi Arabia immediately.
       Israel is also very worried about Iran having nuclear weapons and has warned the world that it may take unilateral military action to attack Iranian nuclear facilities. While Israel and Saudi Arabia both see Iran as an enemy and Saudi Arabia has recently been working with Israel against Iranian interests, Israel is still very concerned that Saudi Arabia might develop their own nuclear arsenal.
       Israel understands that it will not be able to convince the U.S. to forego billions of dollars’ worth of Saudi Arabia nuclear construction. It has presented the U.S. with a list of their concerns about the Saudi Arabia nuclear projects as well as a set of “red-lines” that could trigger Israeli military actions against Saudi Arabia.
        Israel has asked that U.S. negotiations over nuclear power plants with Saudi Arabia be as transparent as possible to prevent surprises that might upset Israel. Israel also wants a list of all the nuclear technology that the U.S. is considering selling to Saudi Arabia. They want to be included in the planning of where the Saudi nuclear power plants should be located. Israel demands that any U.S. deal with Saudi Arabia does not include the right to enrich uranium inside Saudi Arabia. Israel also demands that the U.S. be the only country to sell nuclear fuel to Saudi Arabia if U.S. companies get the contract for the Saudi nuclear reactors. And, finally, Israel demands that the U.S. remove all spent nuclear fuel from Saudi Arabia as quickly as possible in order to prevent Saudi Arabia from reprocessing the fuel to obtain plutonium for nuclear weapons.
       The U.S. Energy Secretary met with the Israeli energy minister a couple of weeks ago to discuss Israel concerns and demands. The U.S. Energy Secretary told the Israeli energy minister that the concerns of Israel would be carefully considered as the U.S. moves forward in negotiations with Saudi Arabia. The U.S. Energy Secretary will be traveling to Israel in October and will discuss the Israeli concerns then.
       Israel’s concerns about a Saudi nuclear program are certainly justified. And they have sufficient influence with the U.S. that their concerns and redlines will be taken seriously. Unfortunately, there are other suppliers of nuclear technology that are negotiating to build Saudi reactors and if the U.S. bids are too expensive or restrictive, Saudi Arabia may well purchase its reactors from other countries that will not attach such restrictions as the Israelis demand.