An Investigation of Major Component Disposal Costs for Advanced Nuclear Reactors PDF Download

Author: Chumani Mokoena
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
Waste disposal is an important aspect for decommissioning of Nuclear Power Plants (NPPs) that requires an understanding of the characteristics of the waste forms. The costs of disposal depend on the activity, volume, dose rate and waste handling/packaging. The U.S. average nuclear reactor age is 40 years old, with many pursuing license extensions. Decommissioning costs are several hundred million dollars, with waste disposal alone predicted to cost over $100 million by the U.S. Nuclear Regulatory Commission (NRC). The current NPP fleet is exclusively made of light water reactors and as such there are no detailed study of decommissioning for advanced reactors that are being developed for deployment. This work modelled activity and benchmarked the disposal costs for a Pressurized Water Reactor's (PWR) components (core shroud, barrel and reactor pressure vessel) against previous work funded by the NRC. The same methodology was then applied towards characterizing disposal costs for a Molten Salt Reactor. Both a crude analytical method that is accessible to the general community and more detailed numerical method with MCNPX and CINDER90 were used to estimate the activity of the reactor vessel and its internals. Disposal costs are based on the Texas Low Level Waste (LLW) facility. Generally, the analytical method overestimated the flux and/or activity of components closer to the core such as the core barrel (PWR) or MSR internals. However, the waste classification was consistent for both methods. The nuclides contributing to the long-term activity of the components throughout the study were Ni-59, Co-60 and Ni-63, while the nuclides with a half-life less than five-years dominated the initial total activity. The PWR core shroud, barrel and vessel were designated as greater than Class C, Class C and Class A, respectively. Based on the disposal costs of the PWR components analyzed, the levelized cost of disposal for a PWR was scaled to be $0.68-$0.9/MWh assuming a 40-year operating lifetime, below the $1/MWh that is typically budgeted. The MSR analysis focused on the activity and disposal costs of the graphite reflectors, core can/shroud, and reactor vessel. Metal components were modelled as either SS316 or Hastelloy N based with an operating period of 5 to 10 years. Graphite reflectors were Class C waste with a specific disposal cost of about $2,200/kg. The core can was greater than Class C waste for both Hastelloy N and SS316. The vessel was Class C for SS316 (5-10 years) and Class C for Hastelloy N (5-7 years) before becoming greater than Class C waste for a 10-year operating lifetime. MSR disposal costs were computed with and without a PWR activation charge limits assuming both an immediate disposal (high cost) and disposal after a 20-year decay period after plant shutdown (low cost). Without activation cost limits, the total levelized cost of disposal is $8.27 to an enormous $779/MWh but the range reduces to $7.25-$20.10/MWh if limits on activation charge are imposed. In all scenarios, the MSR disposal of the reactor vessel and its internals alone were larger than $1/MWh commonly assumed for light water reactors. In addition, the noted cost does not include increased scope for fueled-salt cleanup and decontamination of the considered components as well as primary piping and heat exchangers. Therefore, this work motivates advanced reactor developers, particularly, the MSR community, to estimate the disposal cost of their technologies as it may play an important role in their economic viability.