atw Vol. 63 (2018) | Issue 8/9 ı August/September
| | Fig. 6.
Start-up Delay Times after One Overhaul Period Exposure to VOC.
Plant ID
Compounds
other plants, the re-evaluation has
been performed in 2017.
Figure 7 shows the hydrogen
depletion rates after an overhaul
period of exposure to VOCs in containment
air. A total of 62 tests are
performed with 248 catalyst samples
from seventeen (17) plants as
described in Table 2. The test results
show that the hydrogen depletion
rates are much higher than the
required depletion rate of 0.2 g/sec
that is specified in technical specification
of PAR purchase in Koran
nuclear power plants. A total averaged
value is estimated as 0.270 g/sec with
C1 G H1 H2 M1 P Y Estimated Sources
of VOCs
Benzene ! ! ! ! ! ! ! Paint, Insulation, Glue
Docosane ! ! ! ! Oil
Eicosane ! ! ! ! ! Oil
Heptadecane ! ! ! ! ! ! ! Oil
Heptane, 3-methylene- ! ! ! Oil
Hexadecane ! ! ! ! ! ! Oil
Octadecane ! ! ! ! ! ! Oil
1-Propene, 2-methyl- ! ! ! Paint
Dibutylformamide ! ! ! Insulation
Diethyl phtalate ! ! ! Paint, Insulation
Heneicosane ! ! ! ! Oil
Methylstyrene ! ! ! ! Paint, Insulation
Nonadecane ! ! ! Oil
Tridecane ! ! ! ! Oil
Nonaneitrile ! ! ! Oil, Resin
Tetradecane ! ! ! Oil
Toluene ! ! Paint, Sealing
| | Tab. 3.
Major Compounds Adsorbed on the Sample Catalyst Surface.
a standard deviation of 0.03 sec. The
measured hydrogen depletion rates of
catalysts exposed to VOCs have no
difference with those of new catalysts
that is estimated as 0.2687 g/sec with
a standard deviation of 0.0108 sec.
The recombination reaction takes
place on some active sites on the
degraded catalyst releasing the heat
of reaction. This causes the catalyst
surface temperature to increase
creating a driving force for convective
flow. Increase convective flow
accelerates the reaction rate leading
to further increase in the catalyst
temperature until all the adsorbed
| | Fig. 5.
Hydrogen Depletion Rates after One Overhaul Period Exposure to VOC.
VOCs desorb and all the active sites
are free, i.e., the catalyst is fully
regenerated. The same conclusion
about the hydrogen depletion rate
has been reported in reference [6].
The adsorbed airborne substances
on the catalyst surface are analyzed
qualitatively using GC/MS (gas
chromatograph/mass spectrometer)
method for selected samples from
seven (7) plants. Various VOCs are
detected and their major compounds
are summarized in Table 3. It is
estimated that these compounds are
originated from paints, oils, lubricant,
insulation, glues, etc., which are commonly
used in the plant maintenance.
Although benzene, heptadecane etc.
are commonly detected, the detected
volaticle organic compounds differ
from each plants. In the previous
results, the plant H1 showed a relatively
longer start-up delay time compared
to other plants [8]. There was a
steam generator replacement in plant
G and H when the PARs were installed
in 2013. Further tests are performed
in next overhaul for plant H. The test
results of H 2 represents test results in
the second overhaul (2016) in plant H.
The detected VOCs are different from
the results of the first overhaul (2014)
but the start-up delay time still
remained in relatively larger value
than other plants. The common VOCs
detected in plant G, H1 and H2 are
benzene, hetadecane, octadecane etc.
(the plant G and H are the same type
plants). However, these materials are
also detected in other plants having a
relatively shorter start-up delay time.
From the present results, it is considerd
that the detected materials are
plant-specific and strongly dependent
on the maintenance activities. The
VOC materials presented in Table 3
are at least not strongly related to the
RESEARCH AND INNOVATION 461
Research and Innovation
Effects of Airborne Volatile Organic Compounds on the Performance of Pi/TiO 2 Coated Ceramic Honeycomb Type Passive Autocatalytic Recombiner ı Chang Hyun Kim, Je Joong Sung, Sang Jun Ha and Phil Won Seo
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