ML20212A069

Confinement of Airborne Radioactivity, Progress Rept for Jan-Dec 1975

ML20212A069
Person / Time
Site:	Calvert Cliffs
Issue date:	12/31/1975
From:	Dexter A, Evans A, Merz G E.I. DU PONT DE NEMOURS & CO., INC.
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ML20211R020	List: ML20211R015 ML20211R059 ML20212A069
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DP-1430, NUDOCS 8703030276
Download: ML20212A069 (35)

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,' z, .2nd Pciconinn -- .- e s maregnated c /. -, 4 3, t,ar c c a i n u s a g x -- i ORNL-TM-2860 i t Contract No. W-7405-eng-26. 1 r REACTOR CHEMISTRY DIVISION s. ,e. AGING, WEATHERING AND POISONING OF IMPREGNATED CHARCOALS USED FOR TRAPPING RADI0 IODINE I. R. D. Ackley, Zell Combs, and R. E. Adams MARCH 1970 g LEG AL NOTICE =-.~~.-c- ~.- -. .-.-.~.m- =... ~. e I .mp." wa 1 j OAK RIDGE NATIONAL LABORATORY ) Oak Ridge, Tennessee operated by UNION CARBIDE CORPORATION J for the U. S. ATOMIC ENERGY COMMISSION co i nPt TM 2B L'? l ,,... n '.?;T iS i S '\\ 3 prrk' a

-111-TABLE OF CONTDITS f PAGE Abstract i Introduction 2 Procedure 2 Results and Discussion 1 4 i Conclusions 6 References 7 Tables 8 ~ i Fig'ures 10 e 0 1 I 1 1

.i.... AGING WEATHERING,AND ?OISONING OF IMPREGNATED CHARCOALS USED FOR TRAPPING RADI0 IODINE R. D. Ackley, Zell Combs, and R. 2. Adams ABSTRACT Aging, weathering (exposure to flowing air), and poisoning are processes which might adversely affect charcoal performance, especially with regard to trapping radioiodine in the form of methyl lodide (CH I). 3 Accordingly, some effort has been applied toward investigating the effects of the above processes. The bulk of the data obtained corresponds to four different types of charcoal. Three types are iodized, thus providing isotopic exchange capability, and the other is triethylenediamine-impregnated. The influences of the processes were examined by observing the variation in I of CH 1 rem Val capability for the iodized 3 charcoals or in CH I removal capability for the amine-impregnated charcoal. 3 The results, which were generally in accord with expectation, indicated the following: (1) aging per se has little or no effect on impregnated charcoal performance; (2) weathering with air at around 50% relative humidity has an appreciable effect; and (3) poisoning of iodized charcoal can have a large effect. I e 0 e = 9 b ? .-._.._..________.____...m_,

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I INTRODUCTION . A significcat proportion of airborne radiciodine may exist as methyl iodide (CH I), which readily penetrates beds of the usual types of activated 3 charcoal if the prevailing relative humidity is greater than, say, 30%. Investigation prompted by this potential problem has resulted in the discover / or developnent and subsequent use of certain types of impregnated charcoal which are effective for decontaminating air screams transporting CH b 3 even at relative humidities as high as, for example, 90%. The impregnated charcoals under consideration here may be described as either (1) iodized, l to provide I, I exchange capability or (2) amine-impregnated of which triethylenediamine-impregnated charcoal is the most notable example. Recent information concerning the use of impregnated. charcoals for trapping radioiodine together with referen:es to earlier, and, in some cases, more detailed reports may be found else.:here. Aging, weathering (or exposure to continu?d air flow), and poisoning are processes which, conceivably, may deleteriously affect impregnated ' i charcoal performance, particularly its performance with respect to trapping the radiciodine occurring es CH I. Accordingly, an effort has been 3 directed toward investigating the severity of these three processes. The majority of the data obtained (and those to be presented herein) correspond te four different types of impregnated charcoal; also, the data for each type were all obtained using charcoal having the same lot number. Identification of the charcoal types follows:.MSA 85851 (lot 93066), 8-14 mesh (Tyler), from Mine Safety Appliances; BC-727 (lot 01345), 8-14 mesh (Tyler), from Barnebey-Cheney; C601 (lot 11766),12 x 16 mesh (U.S.), from North American Carbon; and 5% TEDA (UK)(lot W/310B), 8-12 mesh (BSS), from ~ Sutcliffe, Speakman via United Kingdom Atomic Energy Authority researchers. The HSA 85851, BC-727, and G601 types are iodized and the 5% TEDA (UK) is triethylenediamine-impregnated. PROCEDURE Results from a standardized radioactive methyl iodide removal test were used to indicate aging, weathering, and poisoning effects. The conditions of the test, in which CH labeled with CH I is employed, 3 3 are given in Table 1. From each test two removal efficiencies were l l [ .7..~ "$221E I- -, - - - - - - - - - - ---2 = ' ' ~ ~ ~

h 3 calculated, one for the first or upstream 1-in. test bed and one for the two 1-in. cast beds in series. The effect of aging, in the absence of weathering, has not been studied formally. However, a number of applicable results have been obtained in conjunction with other objectives, and a collection of those obtained under th2 Table 1 conditions are employed herein. These results correspond to charcoal stored in closed containers with an air atmosphere at room temperature. For investigating weathering, two setups for exposing charcoal to ficwing air were employed. One was located in a laboratory and the other, in the Oak Ridge Research Reactor (ORR) Building. The charcoal holders used, and there were six par setup, were glass tubes,1-in. I.D., and each contai ed two 1-in. depths of charcoal separated by a distance of about 1 in. The same type of holder was used in the tests corresponding to Tabie 1, so that reloading of the weathered chsrcoal was avoided. In the laboratory, the charcoal was exposed to treated process air under the conditions of, approximately, 40 fpm (superficial velocity), 78*F, and 50% relative humidity (R.H.). The treatment of the process air consistad of having,it flow through a bed of charcoal and a high efficiency filter and then over a pool of distilled water. In the ORR building,- the exposure was.to flowing air taken directly out of the interior of the building near the reactor, and the conditicus were (appror.imately) 20 fpm, 78"F, and 50% R.H. Considering the two differing velocities and based on this one aspect, the intensity of the laboratory exposure was greater than that for the ORR exposure. Periodically, one or more charcoal holders were withdrawn from the weathering setups, and the weathered charcoal subjected to the removal test corresponding to Table 1. Also, once charcoal was withdrawn, it was not returned to either weathering setup. In the case of iodised charcoal, 1 the removal efficiency obtained refers to that for the I of CH 7, 131 3 and this I removal is accomplished via the conbined effect of isotopic exchange and the usual sorption processes. For brevity, the result is of ten termed, albeit inaccurately, as CH I removal. In the case if 3 triathylenediamine-impregnated charcoal, the renoval efficiency can be regarded simply as that'for CH 1. 3

' The first group of weathering results to be presented is for one of the types of iodized ch'arcoal, MSA 35851, and corresponds to a year or more of exposure. After terminating that phase of the work, the decision was j made to investigate a greater variety of charcoals and, of necessity, the planned maximum exposure times were reduced (to 4 months). A schadul'e ' was arranged providing for the obtaining of 2-and 4-month data points for i each type of charcoal to be involved. In order to be able to relate the newer and older results, type MSA 85851 was again included along with types BC-727, G601, and 5% TEDA (UK), and the corresponding results are reported herein. RESULTS AND DISCUSSION The data collected to exhibit the effect of aging alone are shown in. Figs. 1-3. In Fig.1. no trend is apparent, but in each of Figs. 2 and 3 there is a suggestion of a slight decrease in removal efficiency with c time. If the decrease is real, it vould be more prominent for the 1-in. removal efficiencies, and such is the case here. Obviously, however, the number of data points for Figs. 2 and 3 are insufficient to provide the basis for firm conclusions en the effect of aging on either of the two i charcoal types involved. l The earlier weathering results are given in Figs. 4 and 5 for 1-and i 2-in. depths, respectively. The upstream 1-in. depth during weathering is l also upstream during the CH 1 removal test. When ccmpared on either an 3 exposure time or cumulative flow basis, the ORR building-exposed charcoal (actually, building air-exposed) exhibits a much larger effect due to weathering than does the laboratory-exposed charcoal (actually, treated process air-exposed). This observation is, of course, in accord with-expectation, since the ORR building air would not normally be as free of impurities as the treated process air used in the laboratory setup. Thus, the data for ORR building-exposed charcoal are very likely indicative of poisoning. In view' of the magnitude of the overall decrease in the 1-in. removal efficiency for ORR-expcsed charcoal, the decrease being from 90 to 50%, poisoning would appear to represent a potentially serious problem, even when the conditions of exposure are not regarded as severe. Whether 31 the apparent recovery of CH I removal capability indicated by the 15-3 month data point in Fig. 5 is real or spurious is not known. The positions of that point and the analogous one of Fig. 4 can be explained by assuming that, while the first 1-in. depth adsorbed additional impurities during the 4 period involved, the second 1-in. depth, on balanca, desorbed impurities. ^ At 1 east as likely, the explanation is associated with a slight difference in physical locations of the charcoal holders or a slight aberration in experimental technique. 'The relatively low rate of decrease observed for the laboratory-exposed charcoal may be due to mild poisoning and/or due to some more subtle process. The more recent weathering data are shown in Figs. 6-10, where the removal efficiencies corresponding to both 1-in, and 2-in. depths for a given type of charcoal are displayed on the same graph. (In comparing the graphs with each other, allowances would of course need to be made for the differences in ordinate scales.) 1 A summary of the weathering data in Figs. 4-10 'is provided in Table 2 which gives the observed overall rates of decrease in CH I or CH I 3 3 removal efficiency in percent per month. That is, the first set of data for MSA 85851 is for 12-or 15-month exposures, in the laboratory or in the ORR Building, respectively, and the remainder of the results are for 4-month exposures. Also, now referring to the results in Table 2 for /:- month exposures, the second set of data for MSA 85851, the first set of data for BC-727, and the data for 5% TEDA (UK) should be especially comparable since the corresponding test beds of charcoal in their holders were side by side in the weathering setups during the same periods of time. A similar consideration applies to the second set of data for BC-727 and the data for G601. In only one case (in Table 2) is the rate for labora ory-exposed charcoal higher than the analogous rate for ORR building-exposed charcoal, this case being the rates for a 2-in. depth, BC-727, 1st Set of Data; and this exception is in a sense more apparent } than real when allowance is made for the integrated air flows that were ~ (As already noted, the air velocity was twice as high for the involved. laboratory exposures as for the ORR Building exposures.) Considering the results for MSA 85851 and BC-727 types of charcoal, for which two sets of 131 data were obtained, it appears that the effect of weathering on CH I 3 removal capability is not highly predictable, even in the case of rather carefully controlled conditions of exposure. And, probably, even larger variations would be encountered in most real situations. k - m -m .m- -.,.. - - -,., ~, _,.,,,

w In Table 2 the relatively low rates of decrease for the triethylene-diamine-impregnated charcoal, 5% TEDA (UK), indicate that it withstands .the effects of these variations of weathering very well, although, to soms this is related to its initially high CH I removal capability.

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In this connection, mention might be made that the application of triethylenediamine-impregnated charccal would appear to be limited to situations where the possibility of tha charcoal reaching a more than moderately elevated temperature would be virtually zero, since, as demonstrated in ignition experiments on this charcoal, the impregnant volatilizes at a temperature of about 190*C and occasionally ignites.I ) The available results on weathering and poiscning of impregnated charcoal, including other results not presented here, demonstrate that adequati, consideration should be given to these effects in the design and operation of adsorbars containing impregnated charcoal for trapping that radiciodine occurring as CH 1 along with the radioiodine occurring as I

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Obviously, where possible, adsorbers should not b. subjected to extended air flow except when the need to trap radiciodine arises. In those cases where continued air flow is required, an additional upstream bed of i unimpregnated charcoal to bear the brunt of. poisoning due to impurities in the air would be helpful; alternately, an increased depth of impregnated charcoal might be employed. In addition, in the majority of applications, particularly if continued flow pertains, faitly frequent and appropriately designed in-place tests to determine CH I removal capability would 3 appear to be required. CONCLUSIONS 1. Aging of itself has little or no effect on the performance of impregnated charcoal with respect to trapping CH b. 3 2. Weathering with air at around 50% relative humidity results in appreciable reduction in CH I removal capability. 3 3. Poisoning of iodized charcoal may result in a drastic reduction of CH b removal capa W ty. 3 4. Installed beds of impregnated charcoal should be protected from the effects of poisoning and, if feasible, from the effects of weathering. In place tests should be conducted periodically, with a frequency governed by individual circumstances. M

___..e.. ._ __ REFERENCES 1. R. E. Adams, t D. Ackley, and Zell Combs, "Trappin3 of Radioactive Iodine and Methyl Iodide by Impregnated Charcoals," in Nuclear Safety Program Annual Progress Report for Period Ending December 31, 1968, USAEC Report ORNL-4374, pp.,93-105,167. 2. al. E. Adams, R. D. Ackley, and R. P. Shields, " Application of Impregnated Charcoals for Removing Radioiodine from Flowing Air at High Relative Humidity," Paper SM-110/37 (pp. 387-402) in Treatment of Airborne Radioactive Wastes (Proceedings of a symposium held by the Inter-national Atomic Energy Agency in New York, 26-30 August 1968), International Atomic Energy Agency, Vienna, 1968. 3. D. A. Collins, L. R. Taylor, and R. Taylor, The Development of Impregnated Charcoals for Tre'_,,ing Nethyl Iodide at High Humidity, UKAEA Report TRG-1300(W)(1967). N. Coo *C Q *emm e em h... % ee e, w e e em me * **' N ** * *,"**- m e

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. Table 1. Conditions of Radioactive Methyl Iodide Removal Test

• Geometry of test charcoal: two 1-in. depths in series, 1 in. diam.

Air velocity (superficial): 40 fpm Temperacure and pressure: 25'C and 1 atm i Relative humidity (R.H.): 65% Time for preequilibration (to 65% R.H.): 3,16 hr Duration of CH I injection: 2 hr 3 Duration of additional air flow: 4 hr 3 Inlet CH I concentration: arcund 17 mg/m 3 Amount of CH I injected per en of charcoal: 0.5 mg 3 l l l3l 131 ) re oval i he case of iodized charcoal.

• Refers to l (of CH I

3 P e l l l l 1 l 1 l l l l 2 l Table 2. Race of Decrease

• in CH3 I Removal (Decontamination)

Efficiency or CH 1 Trapping Efficiency of Impregnated 3 Charcoals During Weathering e. Charcoal Type Rate of Decrea,s.e,(%/ Month) Laboratorv-Exposed ORR Building-Exposed 1-in. Depth 2-in. Depth 1-in. Depth 2-in. Depth / MSA 85851 1st Set of Data 0.72 0.11 2.7 0.50 2nd Set of Data 2.1 0.45 3.4 0.54 BC-727 lot Set of Data 2.5 0.32 2.6 0.23 2nd Set of Data 1.6 0.38 3.7 1.1 G601 1.7 0.38 3.5 0.56 5% TEDA (UK) 0.51 0.001 1.5 0.02

• As given by results from test detailed in Table 1.

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tG I t ! l 1 j.* goo ORNL-DWG 68-8S(O lo i 4 4 i 950R 2-in. 0EPTHS l {o l l l l o o o ~l l .o o 8 98 r L >-ozU 96 2 u. k w a 94 <t> a o o 2y 92 a a FOR 4-in. DEPTHS H E o D y go O O a ...L o u n -l NOTE: HORIZONTAL LINES ARE AT LEVEL OF AVERAGE VALU I I I I I M M A M J J A S O N D J F M A M J J 1967 r c 1968- = / Figure 1. Effect of Aging on CH 131 3 I Removal Capability of Iodized t Charcoal, Type MSA 85851 (Lot 93066). i / e 1 \\ \\l \\ l.\\, w

~ M I i l ORNL-DWG 68-8809 100 FCR 2-in. DEPTHS

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I .et 98 O O z W 96 o [- FOR t-in. DEPTHS i is. l l 94 o 9 o o2W 92 a: . ~- n [% u NOTE: HORIZONTAL LINES ARE AT LEVEL OF AVERAGE I l 1 VALUES. l l l l l l l l l 88 A M J J A S O N D J F M A M J c 1967 = c 1968 ^ =l i 131 Figure 2. Effect of Aging on CH3 1 Removal Capability of Iodized /, Charcoal, Type BC-727 (Lot 01345). a I e f l 8 I ll i n.

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ORNL-DWG 68-3808 400 FOR 2in. DEPTHS B8 O ,\\ Z Y L58 i N La. LL3 O d FOR 4 in. DEPTHS >o2 tu m H -[ NOTE: HORIZONTAL LINES ARE AT LEVEL o o OF AVER AGE VALUES I I I I I I I I I I I 98 J J A S O N D J F M A M J J C 1967 1968 l Effect of Aging on CH tResoval Capability of Figure 3. 3 Triethylenediamine-Impregnated Charcoal (5%. UK, Lot W/310B). /- l

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.,,,,,--o-g g 80 42 MONTHS ta. > tas a. '5a 70 ORR BLOG.-EXPOSED, AT 20 fpm 3 8 a: at A ra' N [ TEMPERATURE: AMBIENT N 45 MONTHS 50 RELATIVE HUMIDITY:~5O% u 4 40 0 2 4 6 8 40 (at0 ) 3 INTEGRATED AIR FLOW PER TEST BED (f t ) I Figure 4. Effect of Weathering on CH3 I Removal Capability of MSA 85851 Iodized Charcoal (1-in. Depth). h a I t 4. ~ ' ~ * ~ ~ l ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - ~~ l ....-...u... ._~.__,c..

.i 4 ORNt.-DWG 64-4493 E 400 l UNEXPOSED l l 7 ~~0-. , LAB.-EXPOSED, AT 40 fpm ~~- ia ~ ~ -c.. - - - -. . - - -y a ,5l 42 MONTHS E a-95 o i g ORR BLDG.-EXPOSED, AT 20fpm e Wu 45 MONTHS ba 90 2 TEMPERATURE: AMBIENT y RELATIVE HUMIDITY: ~50% [ M l 6 85 L 0 2 4 6 8 40 (m40 ) 4 i INTEGRATED AIR FLOW PER TEST BED (f t ) 3 I Figure 5. Ef feet of Weathering on CH3 I Removal Capability of MSA 85851 Iodized Charcoal (2-in. Depth). O l

t 1 ORNL-OwG 70 433 's -l l 1 l L AB., 40 f pm, 2-in. DEPTH sl __ N l ORR, 20 fpm, 2-in. DEPTH 95 2 TEM PERATURE: AMBIENT w REI STIVE HUMIDITY: ~50 7. G' K E \\N I g ay LAB.- EXPOSED, AT 40 f pm, g t-in. DEPTH OF CHARCOAL E 'g N \\ C. g ORR BLOG.-EX, POSED, 4 MONTHS AT 20 f pm,1-sn. z \\1 EPTH OF CHARCOAL u D 80 .hi*N i N l N N 4 MONTHS 4 O t 2 3 4 (st0 ) INTEGRATED AIR FLOW PER TEST BED (f f3) Figure 6. Effect of Weathering on CH3 I Removal Capability of Iodized Charcoal, Type MSA 85851 (Lot 93066). l l e l l l

~. ORNL-DWG 70-455 100 aNo LAB., 40 fpm, 2-in. OEPTH i I % =-al 98 ORR, 20 fpm,2-in. OEPTH e 96 TEMPERATURE: AMBIENT RELATIVE HUMIDITY:~50 % 8 94 \\ e \\ b 92 \\ b \\ \\ g 8 2 90 ll! \\ LAB.-EXPOSED, AT 40 fpm, \\ t-in. OEPTH OF CHARCOAL yc \\ [ 88 j \\\\ \\ = \\ \\ \\, y _0RR BLOG.-EX, POSED,\\ l 4 MONTHS < AT 2O f pm, CHARCOAL h 4 MONTHS 1-in. DEPTH OF l i 4 O 1 2 3 4 (x10 ) 3 INTEGRATED AIR FLOW PER TEST BED (f t ) lI Figure 7. Effect of Weathering on CH3 I Removal Capability of Iodized Charcoal Type BC-727 (Lot 01345) - 1st Set of Data.

ORNL-0WG 70-453 100 g g 115 L AB., 40 f pm, 2-in. DEPTH g N -e N 95 -e ORR, 20 f pm, 2-in. DEPTH "t e 3 TEMPERATURE: AMBIENT z 90, RELATIVE HUMIDITY:~ 50 %- Gc \\ \\ L AB.-EXPOSED, AT 40 fpm, u. W g \\ 1-in. DEPTH OF CHARCOAL $ 80 N l 3 \\ 4 MONTHS \\ ORR BLOG.-EXPOSED, a: AT 20 fpm,1-in. y ) g DEPTH OF CHARCOAL C E 80 \\ \\\\ \\ \\\\ 75 4 MONTHS 70 4 0 1 2 3 4 (x10 ) l INTEGRATED AIR FLOW PER TEST BE0 (f t3) I Figure 8. Effect of Weathering on CH3 I Removal Capability of Iodized Charcoal Type BC-727 (Lot 01345) - 2nd Set of Data. ,=.e - e l l

ORNL-OwG 70-454 l l 8 4 0 w -e ',40 fpm, 2-in. DEPTH l ~

• a ORR, 20 fpm,2-in. DEPTH 95 TEMPERATURE: AMBIENT RELATIVE HUMIDITY:~507, d

b 90 T 5 N N E \\ LAs.-EXPOSED, AT 40 fpm, 1-in. DEPTH OF CHARCOAL D g \\ \\ as 4 months a N \\ C \\ eo E \\ \\ ORR BLOG.-EXPOSED,( 4 months AT 20 fpm,1-in. a DEPTH OF CHARC0AL 70 O 1 2 3 4 (x10 ) 4 INTEGRATED AIR FLOW PER TEST BED (f t ) ~ 3 Figure 9. Effect of Weathering on CH3 I Removal Capability of Iodized Charcoal. Type C601 (Lot 11766). 4 ,,,,n.-, --...,r,n.-

~ ORNl-0WG 70-434 100 - ---3) l ORR, 20 fpm,2-in DEPTH L AB., 40 f pm, 2-in. OEPTH 99 l-f TEMPERATURE: AM BIENT \\, RELATIVE HUM 10lTY:~50 7 98 s 2 \\ \\ 97 w \\ LAB.-EXPCSED, AT 40\\f pm, \\ 4 MONTHS b y 1-in. OEPl'H OF CHARCOAL

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\\\\\\ 94 g \\ ORR BLOG.-EXPOSED, AT 20 f pm,1-in. \\ DEPTH OF CHA.'ICOAL 93 i 4 MONTHS l 92 4 I O 1 2 3 4 ( 10 ) INTEGRATED AIR FLOW PER TEST BED (ff3) Figure 10. Effect of Weathering on CH I Removal Capability of 3 Triethylenediamine-Impregnated Charcoal (5lll, UK, Lot W/310B).

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