Minimizing the Standard Deviation of the Thermal Load in the Spent Nuclear Fuel Cask Loading Problem

Abstract

The paper assumes that, at the end of the operational period of a Spanish nuclear power plant, an Independent Spent Fuel Storage Installation will be used for long-term storage. Spent fuel assemblies are selected and transferred to casks for dry storage, with a series of imposed restrictions (e.g., limiting the thermal load). In this context, we present a variant of the problem of spent nuclear fuel cask loading in one stage (i.e., the fuel is completely transferred from the spent fuel pool to the casks at once), offering a multi-start metaheuristic of three phases. (1) A mixed integer linear programming (MILP-1) model is used to minimize the cost of the casks required. (2) A deterministic algorithm (A1) assigns the spent fuel assemblies to a specific region of a specific cask based on an MILP-1 solution. (3) Starting from the A1 solutions, a local search algorithm (A2) minimizes the standard deviation of the thermal load among casks. Instances with 1200 fuel assemblies (and six intervals for the decay heat) are optimally solved by MILP-1 plus A1 in less than one second. Additionally, A2 gets a Pearson’s coefficient of variation lower than 0.75% in less than 260s CPU (1000 iterations).

Technical Options and Cost Estimates for Spent Nuclear Fuel Management at the Barakah Nuclear Power Plants

“…(6) SNF can be sent to a reprocessing unit, as shown in path options (6) and (8). However, this option has been excluded from this study because of the UAE national policy strategy, which aims to not implement any type of reprocessing for nuclear fuel wastes [37]. Recently, several reactors from around the world have been permanently shut down, such as in the US, where 35 reactors have been decommissioned [46][47][48].…”

“…Wet storage, wherein the SNFs continue to be stored in an SFP pool or SFPI Dry storage, wherein the SNFs are stored in an ISFSI ese two options have been further evaluated through a comparison of their long-term costs. Based on this analysis, the ISFSI option is more justified in terms of cost-benefit tradeoff, making it a preferable option for ensuring that the fuel is placed in a safer configuration for long-term storage [37,46]. By contrast, in the case of a number of other countries, such as Spain, the SNFs will be stored in pools for several years, after which they will be stored in casks and transferred directly to a centralized interim storage (CIS), e.g., a centralized dry storage (CDS) or a deep geological repository (DGR), e.g., a PDF [35,36].…”

“…Converted to USD, the fixed-cost investments for CDS and PDF for the year 2020 were approximately 310.7 and [5,9,15,37,61,65].…”

“…Depending on these particularities, a number of the models also consider a more specific context to obtain more accurate results for a specific country. Technological options can be adjusted to better match the needs of a country, as seen in France, the US, Spain, South Korea, and China [7,9,24,[31][32][33][34][35][36][37].…”

Theoretical and Experimental Analysis on Influence of Natural Airflow on Spent Fuel Heat Removal in Dry Cask Storage

“…One method of increasing the heat removal from concrete dry storage is adding an air gap as a ventilation channel in the dry storage There are many studies on spent fuel heat removal from non-ventilated dry storage and ventilated dry storage. Several studies on heat removal from non-ventilated dry storage, among others, have discussed decay heat removal after a long-term storage period using the ALGOR code [11,12], heat transfer enhancement in non-ventilated dry storage using inert gas [13], and minimizing the deviation of the thermal load in a non-ventilated dry cask [14].…”