The role of the uncertainty in code development
- CEA-Grenoble (France)
From a general point of view, all the results of a calculation should be given with their uncertainty. It is of most importance in nuclear safety where sizing of the safety systems, therefore protection of the population and the environment essentially depends on the calculation results. Until these last years, the safety analysis was performed with conservative tools. Two types of critics can be made. Firstly, conservative margins can be too large and it may be possible to reduce the cost of the plant or its operation with a best estimate approach. Secondly, some of the conservative hypotheses may not really conservative in the full range of physical events which can occur during an accident. Simpson gives an interesting example: in some cases, the majoration of the residual power during a small break LOCA can lead to an overprediction of the swell level and thus of an overprediction of the core cooling, which is opposite to a conservative prediction. A last question is: does the accumulation of conservative hypotheses for a problem always give a conservative result? The two phase flow physics, mainly dealing with situation of mechanical and thermal non-equilibrium, is too much complicated to answer these questions with a simple engineer judgement. The objective of this paper is to make a review of the quantification of the uncertainties which can be made during code development and validation.
- Research Organization:
- US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Div. of Systems Technology; Nuclear Energy Agency, 75 - Paris (France); SCIENTECH, Inc., Boise, ID (United States)
- OSTI ID:
- 544381
- Report Number(s):
- NUREG/CP-0159; NEA/CSNI/R-(97)4; CONF-961192-; ON: TI97008508; TRN: 98:000219
- Resource Relation:
- Conference: Organization for Economic Co-Operation and Development (OECD)/Committee on the Safety of Nuclear Installations (CSNI) workshop on transient thermal-hydraulic codes requirements, Annapolis, MD (United States), 5-8 Nov 1996; Other Information: PBD: Jul 1997; Related Information: Is Part Of Proceedings of the OECD/CSNI workshop on transient thermal-hydraulic and neutronic codes requirements; Ebert, D.; PB: 824 p.
- Country of Publication:
- United States
- Language:
- English
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