CONSTRUCTION DELAYS AD EXTRA-COSTS ON LARGE AND SMALL NUCLEAR PROJECTS

The new nuclear projects under realization in the Western countries (i.e. Europe and US) are experiencing dramatic construction time-overruns and cost-revisions. The First Of A Kind (FOAKE) phenomenon alone might not explain such high cost increases. Delays are the upmost adverse event that can occur in the construction phase, due to the extra-cost that are engendered, and to the impairment of the whole project management. Initiator events of such delays in the realization schedule of new nuclear project may range from intrinsic to external factors. The former are more linked to the complexity level of the project itself: it seems like the project complexity of current large projects has escaped the control of project management, resulting in systematic construction time and cost overruns. External delay initiator events are more related to the intervention of external forces: e.g. a credit crunch, an adverse ruling by a civil court, extra reviews of the Safety Authority, etc. On account of these delays and related extra-costs, the economics and competitiveness of nuclear power is being heavily questioned. Such adverse conditions occur on large, GW-scale project. Small-Modular Reactors (SMR), like Gen III+ PWR, did not prove on the field, yet, their capacity to build “on time” and “on budget”. Nevertheless they are believed to have shorter lead times and present features able, in principle, to mitigate some construction risks. External delay events can hit in the same way large and small Nuclear Power Plants (NPP) and cause the same halt on the construction activity. Internal delay events should be mitigated by smaller design project, with layout simplifications and more standardized supply chain options. This paper aims to model the construction time uncertainty in order to account for the advantages/disadvantages of the two different alternative projects and assess their economic performance. A large Pressurized Water Reactor (PWR) plant versus multiple SMR with the same total power output, are compared and tested against construction time and cost overruns.