VGB POWERTECH 7 (2021) - International Journal for Generation and Storage of Electricity and Heat

VGB PowerTech 7 l 2021
Study on the integrity of containment against hydrogen threats
5. Conclusion
(a) 0.0s (b) 0.2s (c) 0.4s
(d) 0.6s (e) 0.8s (f) 1.0s
(g) 1.2s (h) 2.0s
(i) 2.8s
Fig. 7. Combustion pressure: (a) A-series, (b) B-series.
In this study, the detailed hydrogen behavior
and combustion in the containment of a
reference NPP were evaluated. The structural
integrity of the containment against
hydrogen threat, such as hydrogen combustion
was evaluated.
For the analysis of the hydrogen behavior
and combustion, first, severe accident sequences
were selected for the reference
NPP, and the amounts of hydrogen generated
were calculated using the MAAP5
code. Next, a 3D analysis of the hydrogen
behavior and combustion in the containment
was performed using the GASFLOW-
MPI code considering the amount of hydrogen
generated and discharged to the
containment obtained from the MAAP5
results. As a result, the combustion pressure
generated in the containment under
each accident condition was obtained.
Subsequently, the structural deformation
and stress response of the containment
were analysed using the ABAQUS code. Because
the hydrogen combustion load in the
containment can take various forms, the
structural responses were evaluated under
three combustion load conditions that are
considered conservative in terms of the
structural integrity of the containment
among the results of the hydrogen combustion
pressure generated under hypothetical
conditions. A structural analysis method
was performed using the dynamic structural
analysis to reflect not only the magnitude
of the pressure but also the inertia ef-
the A-series condition. Therefore, if the
containment integrity is proven by applying
the pressure condition obtained in
the analysis of the B-series, the A-series
based on the severe accident conditions
will be satisfied. Under this background,
the B-series was selected as the
pressure conditions to be applied to the
structural integrity evaluation of the containment.
The pressure behavior in each combustion
load can be identified in F i g u r e 7 ( b ) , as
previously described. For each of these
three cases, the stress, strain, and displacement
of each component were examined to
evaluate the structural integrity of the containment.
Finally, it was examined whether
the maximum membrane strain of the containment
exceeded the criterion of 1.5 %
of the membrane strain at a location separated
by a certain distance. Ta b l e 6 , F i g -
u r e 8 , 9, and 10 present the results for
each case.
From the results, the maximum membrane
strain rate of the containment was 1.32 %
in the case of B3; clearly, this value does
not exceed the safety criterion, 1.5 %.
Therefore, the containment has sufficient
structural integrity against the dynamic
loads generated during hydrogen combustion.
(j) 3.6s (k) 4.0s (l) 4.6s
Fig. 8. Structural analysis for case B1.
500
700
450
600
400
Pressure in kPa
350
300
250
200
150
100
0 4 8 12 16 20 0 2 4 6 8 10
Time in s
Time in s
(a)
(b)
Fig. 9. Structural analysis for case B2.
Pressure in kPa
500
400
300
200
75