Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Homma, Toshimitsu; Tomita, Kenichi*; Hato, Shinji*
Nuclear Engineering and Technology, 37(3), p.245 - 258, 2005/06
This paper addresses two types of uncertainty: stochastic uncertainty and subjective uncertainty in probabilistic accident consequence assessments. The off-site consequence assessment code OSCAAR has been applied to uncertainty and sensitivity analyses on the individual risks of early fatality and latent cancer fatality in the population due to a severe accident. A new stratified meteorological sampling scheme was successfully implemented into the trajectory model for atmospheric dispersion and the statistical variability of the probability distributions of the consequence was examined. A total of 65 uncertain input parameters was considered and 128 runs of OSCAAR were performed in the parameter uncertainty analysis. The study provided the range of uncertainty for the expected values of individual risks of early and latent cancer fatality close to the site. In the sensitivity analyses, the correlation/regression measures were useful for identifying those input parameters whose uncertainty makes an important contribution to the overall uncertainty for the consequence.
Liu, X.*; Tomita, Kenichi*; Homma, Toshimitsu
JAERI-Research 2002-004, 37 Pages, 2002/03
JAERI-Research-2002-004.pdf:2.14MB
One important step in Level 3 Probabilistic Safety Assessment is meteorological sequence sampling, on which the previous studies were mainly related to code systems using straight line plume model and more efforts are needed for trajectory puff model such as the OSCAAR code system. This report describes the development of a new meteorological sampling scheme for the OSCAAR code system that explicitly considers population distribution. A group of principles was set forth for the development of this new sampling scheme, including completeness, stratification, sample allocation, practicability and so on. The calculation results illustrate that although it is quite difficult to idealize stratification of meteorological sequences based on a few environmental parameters the new scheme do gather the most inverse conditions in a single subset of meteorological sequences. The size of this subset may be as small as a few dozens, so that the tail of a CCDF curve is possible to remain relatively static in different trials of the PCA code system.
Liu, X.; Homma, Toshimitsu
JAERI-Tech 2001-054, 49 Pages, 2001/08
JAERI-Tech-2001-054.pdf:1.54MB
no abstracts in English
Homma, Toshimitsu; Liu, X.; Tomita, Kenichi*
Proceedings of 5th International Conference on Probabilistic Safety Assessment and Management (PSAM-5), p.2753 - 2758, 2000/00
no abstracts in English