Production planning for a project job shop, with application to disassembly, evaluation and maintenance of nuclear weapons

Production planning in some make-to-order operations bears considerable resemblance to resource-constrained project scheduling. This type of operation is referred to as a 'project job shop.' The practical problem that provides motivation for the methodology developed in this paper is such a production environment - the Department of Energy Pantex plant in Amarillo, Texas, where nuclear weapons are maintained and dismantled. In order to be useful in practice at Pantex, a production planning model must be able to handle a few hundred tasks (at least), with about 30 different types of facility resources, and 80-90 technicians who hold different combinations of 90-100 different certifications (qualifications to perform specific tasks). An approach has been developed to this production planning problem that is also transferable to project scheduling environments. The formulation uses continuous variables rather than the discrete variables commonly used in project scheduling formulations. This formulation allows time periods of variable lengths, and accepts arbitrary time boundaries (daily, weekly, monthly, etc.) within which resource availability is measured. The solution approach for this formulation is described, and two example problems are used to illustrate application of the model.

Keywords:

• Production Planning
• Resource-CONSTRAINED Project Scheduling
• Project Job Shops
• Generalized Benders' Decomposition