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| NKS Programme Area: | NKS-R | | Research Area: | Severe accidents and Reactor Physics | | Report Number: | NKS-9 | | Report Title: | On Detonation Dynamics in Hydrogen-Air-Steam Mixtures: Theory and Application to Olkiluoto Reactor Building | | Activity Acronym: | SOS-2 | | Authors: | I. Lindholm, A. Silde | | Abstract: | This report consists of the literature study of detonation dynamics in hydrogen-air-steam
mixtures, and the assessment of shock pressure loads in Olkiluoto 1 and 2 reactor building
under detonation conditions using the computer program DETO developed during this work at
VTT. The program uses a simple 1-D approach based on the strong explosion theory, and
accounts for the effects of both the primary or incident shock and the first (oblique or normal)
reflected shock from a wall structure. The code results are also assessed against a Balloon
experiment performed at Germany, and the classical Chapman-Jouguet detonation theory. The
whole work was carried out as a part of Nordic SOS-2.3 project, dealing with severe accident
analysis.
The initial conditions and gas distribution of the detonation calculations are based on previous
severe accident analyses made by MELCOR and FLUENT codes.
According to DETO calculations, the maximum peak pressure in a structure of Olkiluoto
reactor building room B60-80 after normal shock reflection was about 38.7 MPa, if a total of
3.15 kg hydrogen was assumed to burned in a distance of 2.0 m from the wall structure. The
corresponding pressure impulse was about 9.4 kPa-s. The results were sensitive to the distance
used. Comparison of the results to classical C-J theory and the Balloon experiments suggested
that DETO code represented a conservative estimation for the first pressure spike under the
shock reflection from a wall in Olkiluoto reactor building.
Complicated 3-D phenomena of shock wave reflections and focusing, nor the propagation of
combustion front behind the shock wave under detonation conditions are not modeled in the
DETO code. More detailed 3-D analyses with a specific detonation code are, therefore,
recommended. In spite of the code simplifications, DETO was found to be a beneficial tool
for simple first-order assessments of the structure pressure loads under the first reflection of
detonation shock waves.
The work on assessment of detonation loads will continue in the future with full 3-
dimensional simulations with detailed DET3D computer program. | | Publication date: | 01 Febr 2000 | | ISBN: | ISBN: 87-7893-058-8 | | Number of downloads: | 21827 | | Download: |  NKS-09.pdf |
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