atw 2018-09v3

inforum

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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