ML20211R059

Aging,Weathering & Poisoning of Impregnated Charcoals Used for Trapping Radioiodine

ML20211R059
Person / Time
Site:	Calvert Cliffs
Issue date:	03/31/1970
From:	Ackley R, Russell Adams, Combs Z OAK RIDGE NATIONAL LABORATORY
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20211R020	List: ML20211R015 ML20211R059 ML20212A069
References
ORNL-TM-2860, NUDOCS 8703030252
Download: ML20211R059 (23)

Text

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P CONFINEMENT OF AIRBORNE RADIOACTIVITY Progress Report: January - December 1975 s

i s by A.G. EVANS

/ A.H. DEXTER t

i*

l .tpproved by G. F. Mer:, Research Manager i

Reactor Engineering Division

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. Pub 1ication Date: 5epten.ber 1976 -.e .

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5 E.1. DU PONT DE NEMOURS AND COMPANY SAVANNAH RIVER LABORATORY AIKEN. SOUTH CAROLINA 298o1 PAIF4 RED SOA ? t U S S 44 6*ty Af ff ARCu assO ttWttOritatist ADes.asrtim4TeOso unsOf A ConstaACT ataBP te t I .

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( ARSTRACT ,,,

7..

• Efforts are underway at Savannah River I.aboratory (SRL1 and'the Naval Research Laboratory (NRL1 to develop new carbor.-

. impregnant formulations suitable for use in r.uclear power plants as well as in the SRP system. Emphasis has been placed on

> carbons derived from domestic raw materials and impregnated with ,

..' an amine having lower vapor pressure, higher flash point, and lower cost than triethylenediacine (TEDA). Promising results

s. have licen obtained with carbons derived from coat , petroleum, snod, and ec,conut s'id in: prey.nated with a combin c. ion of iodine salts and hexamethylenetetramine (INTA). Serv:ce-aging of several of the IMTA-iodine salt :arbons is also being studied. (

A separate study of the ability of sedits thiosulfate and potassium hydroxide to retain iodine in aqueans selutions in the presence of high-intensity gamma radiation show that concentra-tions of N1 wt *. thiosulfate are required to reduce iodine evolution to less than l'.. A 0.05 wt *. addition of potassium hydroxide has about the same effect. These studies revealed tnat lower concentrations of thiosulfate actually appear to promote evolution of both iodine and an unidentified species of iodine that ti capable of penetratira, several inches of carbon adsorber.

The uaidentifiel iodine compounds are, however, efficiently

). retained by a liEPA filter. This result suggests that the pene-trating iodine may exist in the form of a particulate or aerosol.

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i CONTENTS Intre.Juction 5

. Carbon Studies S 1 Carbon Testiag S Service Aging Studies 6 Particle Si:e Distribution Effects 10 Sbisture Condensation Effects 11 Quality Assurance Tests 12 TEDA Analysis of New Confinement Carbons 12 TEDA Analysis of Used Carbons 13 New Impregnant Developments 13 One-Step Impregnations 14 Two-Step Impregnations 17 IIMTA Carbon Service Aging Studies 19 Iodine Evaporation Studies 19 Experimental Equipment .20 Experime.ntal Results 21 q

influence of Additives on lodine Evaporation 21 No Additives 21 i

. Sodium Thiosulfate 21 I Sodium Thiosulfate + Pottssium Hydroxide 22 Potassium liydroxide 22 Penetrating Form of Iodine 24 Conelusions 26 Appendix - TEDA Analysis 27 References 31 I .

-3 i -

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LIST OF TABLES 7

1 Effect of Service on Type CX-176 Carbon

. 8 2 Effect of Service on Other Carbon Types R

11 ,

• 3 Particle Si:e Distributions of Impregnated Carbons 16 4 One-Step Impregnations of Cocon st Carbon with Constant IIMTA 17

?

S One-Step lepregnations of Coconut Carbon with Constant Iodine 18 6 Two-Step lepregnations of Different Carbon Types 24 7 Iodine Evaporated After Exposure to 10' Rads LIST OF FIGURES 9

1 Iodine Penetration vs. Carbon Service Experimental Arrangement 20 2

3 Effect of Additive and Radiation Dose on Iodine 23 Evaporation (S x 10M Solution of KI) 2S 4 Schematic of lodine Penetration Experirent

{ 28 A-1 Infrared Absorption Spectrum of TEDA Extract 4-1 _

9' -

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d.

CONFINEMENT OF AIRBORNE RADIOACTIVITY Progress Report: January - December 1975 INTRODUCTION This report describes work durirg 1975 as part of a cc.atinuing prcgram to provide adequate confinement of airborne radioactivity in the highly unlikely event of a major Savannah River Plant (SRP)

• reactor accident.: An accident of concern is a loss of coolant accompanied cooling system.by severely degraded perfomance of the emergency This accident sequence could result in significant melting of fuel accompanied by release of airborne fission-product activity such as radioiodine. Some of the iodine would volatili:e into the air in the reactor building, and some might be dissolved in emergency cooling water and transferred to a retention basin.

Because the retention basin is not confined, iodine could evolve into the environment.

Airborne !odine is confined within the reactor building by beds of activated carbon. This rtport describes the continuing prograr. to improve the confinement capabilities of these beds.

A second part of this report describes the laboratory evaluation of additives that could retard volatili:ation of iodine from aoueous solutions.

~

CARB0f4 STUDIES Carbon Testing Previous confinement studies at Savannah River have shown that iodine retention on activated carbon is greatly influenced .

by impregnants on the carbon, temperature of the carbon beds, '

length of time the carbon has been in service, coisture content ,

' of the air passing through the beds, api radiation exposure to iodine-bearing carbon in the beds.: is

• To improve the perfomance of the confinement system, un-lepregnated carbon that had been used as an iodine adsorber for many years was phased out of service and replaced by Type GX-176 carbon *, a coconut carbon toimpregnated with potassium iodido and triethylenediamine (TEDA).83 Char.geover to the new carbon was a

conpleted in 1975.

, i

• Product of North Amcrican Carbon Company, Columbus, Ohio.

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The use of impregnated carh:n necessitated development and implementation of new quality assurance ter.ts to confim vendor compliance with purctase specifiestions. Neutron activation analysis and til measurements 85 were used to ensure both preper iodine salt impregnation level snd a proper balance of I . K, and .

pti for optimum performance in the system. A TEDA extraction -

procedure was developed for use with the QA tests. Details of

- this procedure are reported in the Appendix.

Installation of the new type of carbon required aging studies .

to determine the iodine retention of this carbon in serv 4ce.

Improved performance of the new carbon was demonstrated during 18 months of continuous service. These service-aging studies will be cor.tinued.

Studies are also in progress to develop an impregnant formulation that will overcome the disadvantages of TEDA-impreg-nated coconut carben: high cost, relatively high TEDA vapor pressure, relatively low TEDA flash point, and dependence on foreign sources for raw materials. Cooperative efforts between the Savannah Riser Laboratory (SRL) and the Naval Research Laboratory (NRL) indicate that sever 11 carbon-impregnant com-binations that use domestic base carbons with iodine salts and hexamethylenetetramine (IlMTA) may be as effective as the TEDA-K!-

coconut carbon combinations.

Service-Aging Studies Changeover from the unimpregnated carbon to Type GX-176 carbon 83 began in May 1974 and was completed in July 197S.

Service-aging studies on the new carbon were started early

in 1974 when small samples were installed in test beds in the Carbon Test Facility (CTF) in the P reactor area, and periodic

sampling of full-si

ed carbon beds was also begun. 3 Carbon with j up to 15 months exposure to a tactor bui. ding air was tested for

- iodine penetration with the SRL radiolytic desorption test."

All sampics of Type GX-176 carbon perfomed better in a radiation

' environment than did the unimpregnated carbon with no service exposure.

{ ,.

Significant dif ferences in service-aging rates were noted i

between CTF-aged sauples and carbon removed from the confinement l .

system. Type GX-176 carbon in the confinenent system continues

, to outperform both the CTF carbons and samples of 1pe G-615 carbon

• exposed earlier in the confinement system.8 Test data i

• Product of North American Carbon Company, Columbus, Ohio.

i 4

i

m = : n. :<< .. . - ~, ,. . = . _ - -

-- w -- = ;v.smr? a for Type CX-176 carbon are shown in Table 1. Data for Type G-615 carbon and unimpregnated Type 416 carbon

• are shown in Table 2.

These date. are also presented in Figure 1. Reasons for the more rapid deterioration of Type G-615 carbon and the CTF sampics of Type GX-176 carbon are discussed below.

. TABLE 1 Effect of Service on Type GX-176 Carbon t ar?'ecAy, Cmartmt Iod~' "

. f0M t O .7:#:ltr 548$ne Penstantices, 1

0 (Control) 0.025 10.01 8 6 K-2 0.052 10.03 b P-2 0.062 a0.04 8 P-2 0.051 10.03 -

12 K-2 0.0t,0 20.04 12 P-0 0.055 10.03 18 K-2 0.090 10.02 6 CTF 0.129 "~

'.5 CTF 0.249 12 CTF 0.156 15 CTF 0.207 18 CTF 0.375

o. Deternined by radiation desorption test: I hour loading, 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> desorption at 80*C and j 95*. relattre humidity in a radiation field of i = >l.5 x 10' rads /hr absorbed dose rate in carbon.

b. Average and standard deviations given for replicate determinations for confinement carbons. Single determinations given for

, , CTF ct.rbons. ~

e. Carbon esposed at flow rate of 67 FPM (1.25 m normal flow rate). Service age is estimated by assuming linear relation- -

ship between flow rate and se vice.

I e

l .

l _ __ _ _ . _ . _.

TABLE 2 Effect of Service on Other Carbon Types

.: san Ser]!:c, Ompart-cr.c 10dinc ?enetmeicn,

?p Arnt :a  :.*w&ar P 5

416 0 (Control) 0.33 20.04 416 21 C-2 0.61 20.10 416 33 P- 2 1.04 20.20 416 33 P-3 3.61 20.80 l

416 46 K-3 4.38 21.20 G-615 0 (Control) 0.03 20.01 G-615 6 C-2 0.07 ?0.04 G-615 9 C-2 0.129 20.05

c. See Table 1, footnote a, for test conditions; values listed are averages with standard deviations,

b. Unimpregnated carbon formerly used in the '

confit.ement system. ,

c. An 8 x 16 mesh carbon containing 2*. TEDA -

(Type GX-176 carbon is a 10 x 16 mesh carbon containing 1*. TEDA), Both Type G-bl5 carbon and Type GX-176 carbon contain 2*. K! and l'.

fire retardant.

i a' i*

-S-i i

.\ ,

. . . . . . , . . . ~ . .. _ . . . . . .-..=_=_.-~w.~

6.0 i

. i l l g g i g .

4.0 - O '

S 2.0 -

1.0 -

$ O.8 ~

ree Micar c- 0.6 - # -

.9

$O.4 - g -

= a e r -

1 O e 4I6 Carbon e 0.2 -

U (comp. 2 8 3) g _

o O O GX-176 Carbon (conf. sys.)

QA O GX-176 Corben 0.1 - (CTF)

O A G 615 Carbon I '

O.08 -

g Comp. P-2 \ (comp. C-2) - '

O.06 O O# * ' ' -

- 0O OComp. P 6 .

- 1

\

O.04 -

Corr p. K+2 ~

A 0.02 ' I ' I ' I ' '

! I ' s O 10 20 30 40 50

• 60 Carbon Service, months FIGURE 1. lodine Penetration vs. Carbon Service i

)

' 1

.I 6

y , ; Q(v.Jy P A,.:b z g . ,. p g.; :% T,y @. .$ 4... 4 >g i si .- .-

. . x -

i T.:r: ::a .'::. :!.1:rihri:>: Sf;L':2 Three types of impregn2ted carbon nave received service exposure in the SRP confinement system:

e Type G-615 carbon", an 5x1b mesh .oconut carbon impregnated

/

with 5', TEDA.

s.

e Type G-615 carben, an Sxle =esh ceconut carbon impregnated with 2'. TEDA and h Ki (plus a flame retsrdant).

e Tyne GX-176 carbon, a 10xto riesh coconut carbon coi=pregnated with 1*. TEDA and l'. KI iplus a (1sme retardant) .

Types G 61$ snd C-bl5 carbons were removed frot service after exposure of only e conths and 9 co sths respectively, because of tne possibic ri A of carbon ignitten." Initial ss= pics of a prototype Type GX-176 carbon were installed in the CTF slong with Type G-615 carbon smples. Later, production lots of Type GX-176 carbon with a finer cesh si:e were i sced l in the confinewens syster.

- As discussed in the previous section, the full-si:ed confine-ment-systen beds of the production lot of Type GX-176 carbon with 18 months exposure have continued to perfor:. better ths:. either the 1ype LA-176 carbon exposed in the CTF c,r the Type G-615 carbon exposed :n the confinecent system for 9 months.

Sieve analyses indicate that differences in perfornsuce of the three carbons (Type G-bl5, prototyre GX-176, and conficement ,

- Type CV-176) nsy be due to variations in their particle site distrioutions. The dats in Table 3 show that both Type GX-615 carbon and the prototype lot of Type GX-176 carbon contain s Isrger weight fraction of particles greater than 1.10 c:2 in diameter (the nominst opening in a U.S. Standard number 14 sieve) than does the production let of Type GX-176 carbon. Although other factors (to be discussed in subsequent paragraphs) 'isy affect the perfornance of the (.TI: :srbons, sgin;'. rates of carbon

• types GX-176 and C-ol5 are pransbly aficcred more by particle si:e distribution of carbon granules than by impregnant content.

• 6 roduct of 53srnebey Cheney Campany, Columous, Ohio

" Product of North Accrican Carbon Cenpany, Columbus, Ohio a

. _ , . . -- . _ . _ __x _

)

• i N .- /

l l

- , - , - - . - - - - . . - - - - . 1

~. i 1

TABLE 3 Particle Size Distributions of Impregnated Cartons PsTC CX-17C P.srel ase Qpe (pisto-

.'. 2 :iac, C-t'):,$ typey' 7 tic CX-17C Cpecifi-(confincrvn t)0 catimc

'in '.o. A Sieve 4.3 0.0 0.0 50.1 th Nt. IC # sieve 24.6 7.9 0.1-0.6 15.0 on No. 12 Sieve 37.1 5.3 6.5-8.4 -

(5 .No. 14 Sieve 25.8 61.3 34.1-37.2 -

W Li. Ib St.r e 6.5 24.1 50.4-54.8 190.0 th

• o. IS Sieve 0. 9  !.4 2.2-4.5 15.0 Through No. 15 0.3 0.0 0.1-0.2 gl.0

. Lt.S. Standard ASD1 E-ll series sieves.

Production lot exposed in C 2 compartment April throua,h ]

December 11872.

l

. . Cll- ca rbon.

. Produ:

!!ay 11874 tion lot installed in centinement system beginning Values given are the range of values obtained from the Ib .ubiots comprising the full purchase crder.

This specification did net apply to the Type C-bl5 or pr.itotype Type tiX-17b carbons.

.'Olatusv Cor.daneation Effects During the first six conths of operation of the rTF with the prototype GX-176 carbon installed, meistute condensation and corre*. ion problems were experienced. In one case, ecisture i conJenution corroded the stainless steel retaining screen and 6 the alu innum test-bed body. and leached impregnants from the ca rbon. The combined effects of impregnant leaching and con-tasination of the carbon with corrosion products probably contributed to rapid deterioration af the CTF carbon during the

. . . s . . .

l first six months 'riole 1). The CTF data (Table 1) show that the carbon deteriort ted more slewly between b and 12 months (when less condensation oecurred due to warmer weather).

To resolve the differences betmeen aging rates in the CTF sad in the confinement systems, production lots of Type CX-176 carbon were in t alleJ in the t.ry, and the test beds were tnermally o-insulated to mit.asi:e moisture condensation. Use of production lots of Type GX-170 carbon in the CTF will also permit evaluation l of the particle-si:e distribution effects because exposure con- I ditions and impregnant Icvels will be the same in the CTF for both the production and prototype GX-175 carbon.

Quality Assurance Tests a

Earlier studies at sRL hasc show the importance of proper balance of iodine, r,otassium, and pl! for optimum carbon perform-ance **85 and the need for control of TEDA content to reduce the 8

ha:ard of carbon ignition.8 3

• 8' P,esent sti. dies indicate that close control of particle si:e distribation is also needed. The effect on performance of each of these parameters is great enough to dictate extensive quality assurance tests of ala carbons installed in the SRP confinement system.

Type GX-176 carbon used at SRP was subjected to a variety of chemical, physical, and iodine-penetration tests before it was irstalled in the reactor off-gas cleanup system. Among the tests

• p. rformed were: ieve analyses, di analyses, iodine and potassium analyses (by neutron activation analysis), iodine-penetration. tests using both the high temperature (IS0*C) test and the tsdistion test, and ignition temperature tests on each of the 16 sublots of carbon received.

" EDA Analycle of .'.'e 1 Ccnf *u~a 1: Carbons

• Khen the carbon was purchased, no quantitative analytical j

P procedure was available for arcertaining whether the material I met the TEDA content specifiestions. Ignition temperature tests on the carbon indicated that none of the sublots contained sufficient TE"A to cause premature ignition t.nder adverse cperating conditions, se installation in the confinement system was started without a specific TEDA analysis, flowever, an analytical procedure wss developed and all sublots of carbon were l

analy.ed before the installation was completed. The procedure involves measurement of infrared absorbance of TEDA that is i

extracted into CCI..

/

1 1

? +.

88u59

. . .- . . n w , m .~

,v f

TEDA concentration rar.ged from 0.86 to 1.08 wt % with an average value uf 0.99 wt i and a standard error of 0.08 wt %. The purchase specification for TEDA concentration on the carbon was 1.0 wt % with a range of 20.1 wt *. (an agreed-upon range pending specific analytical data to show the actual range). Apparently the manufacturing controls were effcetiv6 because only two sub-

• lots fell belov the minisuu ranga (one by 0.03 wt % and another 0.04 wt %).

TECA Analysis of Vaed Carbons Determination of TEDA by infrared absorption is possiblo only in the absence of other hydrocarbons (see the Appendix). l During the analysis of the new carbons, spectrum shapes were scanned visually for evidence of interference by other compounds.

The absorption spectra wera con:istent with those observed for pure TEDA 17 CC1.. To determine applicability of the procedure to used carbons, a sample of Type GX-176 carbon that had service-aged fer 6 months in the confinement system was analy:ed. The spe:trum shape was considetably different; it had a stror.ger peak at a wave 1er.gth below 3.3 cm than did pure TEDA. The calculated concentratien of TEDA (based om absorbance at 3.71 um) was 1.61 wt % compared to 1.03 wt *. TEDA for the same sublot before confinement-system exposure. The different spectium shapo and the increased TEDA concentration indicate that the method car. net be used in its prescrt form to determine TEDA in scryice-aged carbons.

No further development work to adapt the procedure to used .

carbons is planned. The quantitative loss of IEDA from carbon

,. dried at 140*C suggests that a procedure based on thermal ,

strf pping rather than solvent extraction may be possible. Gas chromatography could be used to separatt Teat from the acnospheric contaminants.

New Impregnant Developments

• Although the use of TEDA as an impregnsnt to enhance methyl lodide retention by carbon has been establisned,'e 8' TEDA char-coals have the disadvantage of the high cost of TEDA pound in bulk lots), potential ignitien ha:ards,8b 8"(%$8.00/ and the stripping of TEDA from the charcoal at temperatures ss low as 140*C. For these reasons, studies are continuing both at SRL and NRL to develop other eftcet!ve inpregnants or impregnant combinations for organic todide trapping.

- 13 -

-~~-. .

k i

British 4tudies have shown that other amine corpounds pyridine, nor; holine., piperidine, and others) are also effective a earben impregnants. *

• ll.mever, like TLDA. these compound

'leb ivetoret.itively 1 *,-*C" low melting and/or boiling points (ranging from 1 and are not 8uitable impregnants for applications

.i t elevated te:peratures.

preliminary Jata on carben impregnsted with triethanot. wine

, ill A. bp 2** to 2 9'C) were given in the r.revious progress report.8'

'.ubsequent data from both SRI. and NRL show that TEA is not as y effective a> ll.t'A. particularly for ': ethyl lodide trapping, therefore, a search was undertaken at .NRL for other smine cors-piaunds having both a low vapor pressure at 100*C and sufficient scrtiary anine functional groups to react with methyl iodide.

the coepound hexamethylenetetramane (INTA. C6!1oN.) was found

- to have both thermal stability (it sublimes at 20T*C) anJ ilequate iodine retention preperties when cochined with inorganic iodine salts and potassium hydroxide.

IrfrA is used conscrei lly as an accelers or in vulesni:Inc rubber, in the manufacture of formaldehyde-type resins, and as

.: poison gas absorber. It is used mediesliy as urinary antiseptic and has been used as an anlytics! resgent for the eletermnation of s!!y1 halides. Th. price of listrA is about

$2.25 per pound in buli lots (less than c. e-third the cost of IIDA). Even though I!!frA is also useil c. ercia!!y as fuel for some types of camp stoves, carbon ignitloa terperature is not

_ lowered by li.'fra icpregnation leveas as high as O'..

u-::c; i~pecp:2: cu  ;

i Pre!!minary *tudies at NHL showed that ilVTA-impregnated 6arbons are effective for trapping methyl lodide only when the Ir pregnants are combined in .3 specific sequence before the inpregnation step is begun.8 l i r.it , the ll3ffA and I; nust be lut tmately nixed (i;rour:d together with a .aortsr and pestle or

, in a laboratory hall till). Then potassium hydroxide, water and K! (when used) are added, nd the slurry is stirred until a solids-free solution is obtained. Stirring for several hours is frequently necessary. the clear, solids free solution can y

then be added to the ca.rhon by drip or spray sJJition techniques

, that uniformly impregnate all the earlon granules. The total

.olume of solution added nust be carefully controlled to saturs?c.

I,ut not fluod, the carbon.

Larlier work with iodine salt inpregnatteris (with or without ilIN shomed that the volume of water in the irpregnation solutions si.uuld be the amount of water required to saturate the carbon (with purer allowance for rinse notations to transfer all the impregnants

-II- .

s*

_ . _ . , _ . . ., _ _. ._ .. _ . - . . . . . . . . . . . - . . - . ~. -

to the carbon). The InstTA solutions, however, must be prepared with about two-thirds the water to avoid carbon flooding in this single.

solutten impregnation technique (use of '.0.4 al water /g carbon for a sharcoal normally requiring 0.6 ml/g for saturation). The reason far the lower saturation volume has not been investigated, but the carbon micropere structure is probably partia!!y plugged by the large hydrated, iodinated IDfTA molecule.

SRL participation in the IlifTA carbon development effort has heen directed toward adapting the impregnation techniques to a variety of base carbons. Studies a were initiated with Type G-210 coconut base carbon * (%1100 m /E surface area, 8 x 16 mesh particle si:e distribution). Previous studies at SRL have shown the necessit alkalinity.8{ of proper balance Thus, all the SRL among formulationsiodine, pctassium, are based on and an iodine-to potassium weight ratio of 2:1 (stom ratio of 0.6:1) which was found most effective in the earlier studies. Because no data were available on optimum impregnation levels for the IDUA-iodine combinatic.1 on coconut carbon, twn series of samples were prepared. The first series consisted of syste=atie variation of the iodine content and form from 1*. te 3'. with a constant 5'.

lonA. Samples prepared for this socies were made with and without flame retardants to stuJy the effect of the flame retardants on Ignition temperatures and iodine penetrations of IDR'A formulations.

After the samples were tested for methyl iodide penetration at NRL, the optimum combination of iodine. iodine salts (1% icdine as 13, l'. iodine as 1*) was used to prepare the second series in which the llMTA content was systematically varied from 1'. to 6'..

Test data from the first sample series (Table J) show that o

methyl iodide p:netration on samples without flame retardants (first 5 samples) is lowest at 2'. total lodine with half the iodine in the ele = ental form (! ) and half the iodine in salt form (l') . Data on sanples incorporating flame retardants also show that the 12.l* combination is best and that moncbasic sodium phosphate INall:PO.*ll:0) is a better additive than the dibasic

, salt (Na:llPO.* ll 0). 2 I -

Test data from the second sample series (Table 5) show that .

2'. IIMTA impregnation is the best lisfTA con::ntration for methyl lodide reter.tlon (lowest penetration values) even though the

, thernal penetratir.c test data are higher for this combination.

Data for Type C 615 carbon (a commercial product of the same base carbon containina 2'. TEDA) are sho n for comparison.

i i

• Product of North American Carbon Company, Columbus, Ohio.

l '. . ,

t e

__ , _ , _ - - ~ _ _ _ , _ _ _ . , _ - - . ,.m.,____- ._-- .___.,.__,_-..-,--_,_._m ,,.-,..y,,,... ,,y ,_ -, _ _- _ , . _ . _ . - .

4 TABLE 4 l

i One Step lepregnations of Coconut Ca4ond 'dith Constant DeffA

.'=~wp:2 tim *e:<. :o, S ,, gg y,. . p,., g ,,,, gm, ,

.ff A !s l'* CH CCher (1/K) pH # Terp., *C Jgd cy,t d 5.0 1.0 . 0.7 - 0.024 275 0.00061 9.32 3 ,

t 5.0 1.0 1.0 0.7 - 0.041 325 0.00031 1.33 ,

5.0 2.0 . 1.4 - 0.037 265 0.00041 2.53 5.0 3.0 . 2.1 - 0.043 265 0.00045 2.01 5.0 1.0 2.0 0.7 - 0.053 315 0.00000 2.39 5.0 2.0 . 1.4 1.0I 0.036 355 0.00000 3.05 5.0 1.0 1.0 0.7 1.0I 0.033 39 0 0.00u52 1.se 5.0 1.0 1.0 0.7 1.0# 0.045 355 0.00057 3.18

e. Tne G 210 base car' ion (see test for description).

b. As El. AJJition calculated on the basis of weight percent iodine aJJed.

a. Determined free analyses of carbons after impregnation (Reference 15).

d. sal. Thermal Desorption test (see test for test ceditions).

e. NRL methyl lodide test data. Test run at 25'C, 9M relative humidity, '

5 og Olst/s C loadings and 0.25 second stay time in 2.in. deep carbon bed.

f. NaHaPO.*ha0 (manobasic sodium phosphate) flame retardant aJded. ,

p. Nastfo.*2ifa0 (dibasic sodium phosphate) flame retardant added.

7 e

h

... , . . . .. , ..,me,.ww cco.-ssee;w l

TABLE $

une Step Impregnations of Coconut Car *aan* With Constart lodine in t. ..mtion levels, s y,,g, gy ggg, lodine Penetmeion, s i' h *C.*,; la l~b KCH Ct Inte (1/KJ/; h Te.p , *C la b CHsi b

2.0 #

I.0 1.0 0.7 1.0 0.034 350 0.00047 0.99

. J.o 1.0 1.0 0.7 1.o' O.034 370 0.00141 0.65 3.u 1.0 #

t 1.0 0.7 1.0 0.029 415 0.00105 1.19

. J.0 1.0 1.0 0.7 l.0 0.036 42 0.00092 1.37 5.0 I.0 1.0 0.7 1.0 0.03s *90 0.00052 1.46 6.0 1.0 3.0 0.7 1.0' O.037 435 0.00074 1.76 0.0 . (2.0 EI) . . 1.C 0.039 360 0.0060 3.79 411 tul J. 13 rc a; J10 base carbon (see test for Jescription).

J. Nov lable 4 for Jetaats. '

. Llis it). .llau.

J. 4; oll Carbon (2*. TEDA).

.. I'r yrsatary flame retardant.

N: .~tep fr; rey.a:Lan Work at NRI. han shown that applicatien of the iodine compounds and IDrrA in two separate impregnation steps produces a charcoal with equal or better methyl lodide retention properties than the i carbons produced by the single. step impregnation technique. *'

Since the lodine. iodine salt mixture along is freely soluble in i hater, as is the ll>frA alone, the separate impregnation solutions can be prepared in a few minutes (without the lengthy stirring '

required in the one-step lepregnation). The lodine salt mixture dissolved in about one half the volume of water required to saturate the carbon is added to the carbon first. The IBfrA in an equal volume of water is then added. It is not necessary to reduce the water volu.me as it was for the one. step impregnations.

Proper control of thu pil of the two impregnation solutions is required, however, to obtain a final product in the desired pil range (19.5). Thus, both solutions must be titrated to approxi. -

mately the saae pil before the impregnation step. *'itres depend e on the base charcoal used. Low pil carbons, such as coal and petroleum, require more Koli addition than do the highly alkaline i coconut and wood charcoals. .

i

. 17 l

d.

Two series of test carbons have been prepared at S:tL by the two-step impregnation technique. The first series was prepared before test data in Table 5 were availsble and contained 5*. !!)fTA.

Test data on this series of two-step impregnations are shown in Table 6. The second series of two-step impregnations was prepared with M lthfft. Test data were unavailable at the end of the report period.

The data in Table 6 show that the two-step impregnation

\.) ,

technique produces a product about equivalent ta the one-step technique i.ith coconut base carbon (1.78 methyl !odide penetration for the two step method vs.1.86*. methyl iodide penetration for the one-step method). These data also indicate that 5', II5frA retains methyl iodi e more effectively on all the non-coconut base carbons (particularly ceal carbons) than on the two coconut charcoals tested.

TABLE 6 Two Step l ;regnations' of Different Carbon Types 9:no t' art st u

. ~y;d . er x .-2:is *

. ,.*:i t i.:e.

.70. "

.stsiis (Ui:)/;H .'s=7., *: lg' CH s!'

1. p.0u289 1,74 G-210 C.nunut 0.030 398

1. 0.0u231 2.47 G-212 Coconut 0.u27 335

1. 450 0.00141 0.50 G-352 Coal 0.090 BPL Coal 0.086 433 0.00337 0.53 337 letroleen 0.095 425 0.00721 0.73

1. 436 0.00150 0.99 GX-202 m :pA 0.045

=. 5% IMIA, l'. la , l'. l * , 0. 7*. Loll, l'. Nalla PO. *ll 0 (see text for impregnet son details).

k. See Table 4 for test details.

3. Produst of . North Ascrican Carbon Company, Columbus, Ohio.

d. I'roduct of Pittsburgh Activated Carbon Division, C. !gon Corporation, Pittsturgh, Pa.

c. Product of hitco Chemical Corporation, New York, N. Y.

. IS -

,,,.--~***' ~

L

' " ' ' ' ' ~ ~ ' ~

_.._,~m..,1 10.*: *.12ri t n . ce.: ec Q'y ::t:adia Since lotlA is . now impregnant,'serviec aging eff?ets on ,

lonA-impregnated carbon < are uncertain. Thus, studies w!!! he conducted on the effect of <erviec on the iodine retention proper-ties of the ItllA cariens before such carbons are recommended for use in off-/as cleanu;> syster.s. Addi.ional studies are needed ,

on the sers tee. att rit ion rates of the non-coeonut base earben<.

. the t'i rst test progran is in progress. Sacpler of coconut earbon c9ntaining -' loTIA were anstalled in the CTI in 19~5 and are scheduled for remmal af ter b. 12. and IS r.onths exposure. The

, first sample is scheduled for rezov21 in April 19 6.

~

Additional IDfTA carbons are scheduled for installation in the CTF as test positions become available (April 1976). Testing of coconut , coal , petroleum , and wooJ. base carbons impregnated with 2*.IDfTA are included in the service-aging schedule so that both iodine retention properties and service attr! tion properties cra be evaluated.

10 DINE EVAPORATION STUDIES A loss of coolant accompanied by severely degraded performance of the emergency cooling system could result- in melting of fual and dissolution of fission products in the emergency coolant. Volatile fission products such as iodine could subsequently evolve from the emergency coolant and be released to the environment. One cethod to reduce the potential for such evolution is the use of additives that would retain the volatile, fission-product iodine in solution.

In earlier SRL studies 85 of possible additives, sodium thio-sulfate appeared to be the most promising. Laboratory-scale experi-ments in the abscace of a radiation fie13 shcwed that iodine release e could be reduced by 10' with a sodium thiosulfate concentration of '

8 x 10 ')! in a 5.5 x 10 5)! aqueous solution of iodine. Other work J indicated that although the combined effects of temperature and radiation would destroy a portion of the thiosulfate, sufficient additi"e could probably be maintained to keep the iodine in solution.

These tests, however, evaluateJ only the -tability of thiosulfate in the radiation field, not the iodine-thiosulfate-radiation combination.

. To examine the combined effect, laboratory-scale experiments were performed with the SRL ' Ca IrradiJtion Facility to obtain radiation doses 06 10' to 10' rad, doses comparable to those expecte.1 during the hypothetical accident. During these e*periments, a combination of additive and radiation field was found that generated an iodine speeles that could not be trapped by carbon beds but could be collected on a llEl'A filter. Attempts to identify the volatile species have been unsuccessful to date. -

Experimental Equipment The SRL "Co Irradiation Facility 88 which providet, 2.7 x 10' rs.da/hr was used to irradiate aqueous solutions of K1 t.i deses of

{0' 88 rads. The KI in each experiment was " tagged" with %1 mC1 of 1, and scit.tillation counting equipment was used to measure the 888 volatill:ation of the 1 as a function of radiation dose imparted to the solution. Typically, 4 liters of solution in a stainless

- steel vessel was irradiated for %5 hr while air flowed over the solution surface at 13 1/ min. The volatili:ed 8 88 1 was transported by the flowing air and collected on activated carbon that was -

. monitored with a scintillation counter (Figure 2). An inventory 888 1 activity of all system (material balance) was made of the components after each test. Pre-irradiation pit was typically about 7, and in several experiments this was increased to >10 by adding KOH. The solutions were not buffered. Solution temperature during irradiation was %50*C.

4,,

HEPA _

Co' coa __

cownte, In F ' "" ees

] iPhoto,mwit.pe.e, se.nt. 4,.o, j Ce ystel E e nowst

,,3 u ete,

~ ~ ~

Coreca . Sotesy ,,,,,,,

eens seas I -

_y u ,

G7 4,E W '. 4 ,.

, kh

• Soluteen Con Q q4 .- ,

l Soco wen- ,

f E '

!' --**co sNgs

- i i.;

. 'l I ; .! .

u g. i.

) .

s

' . :_DQ -Y,. -.. a u "

i FIGURE 2. Experimental Arrangement O

f . $

s i '.

. . . . -- _ _ - _ _ . _ _ a, Experimental Results Experimental results are given in two parts: 1) the effect of additives. and 2) the attempts to identify a renetrating form of iodine that was found during the experiments.

In;%ence of Additives on Icdir.e Evaporation Investigation of the influence of additives on iodine retention included nine experime.ts, one with no additives, two -

with sodium thiosulfate, four with sodium thiosulfate and KOH, and two with K0ll.

..') /ddleives. Irradiation of a water solution containing K!

(5.6 10-'M) to a dose of 10' rad caused the evaporation of 14.6%

of the iodine (Experiment 1). This result compared with 16 to 34%

evaporation of iodine 85 from a solution co.itaining elemental lodine

(*.1.5 a 10**4) in the absence of radiation. These results indicate that radiation converts ionic iodide to volatile iodine, most probably through Oil radical attack of the iodide Gil * !" + 1 + Oll' (1)

The oil radicals result from the radiolysis of the water. Further, because the iodine evaporation is about equivalent in the two experiments, the conversion of iodide to iodine is thought be be Limost quantitative.

3..!*:c- :';;ies:e fate. hhen sodium thiosulfate was added at a molarity (5.5 s 10**) approximately equal to that of the KI, an almost,guantitative release of the lodine occurred (94% in one experiment and 90*. In another). Thb ineffectiveness of the thiosulfate at this concentration is thought to be due to the radiolysis of thiosulfate by the reaction ' 8

, S:0$' + 4(0) + 1130 + 2S0** + 2H' (2) augmented by acil decomposition of the thinsulfate by the reaction ' 8 S0j"+ ll*+hsOi+1150i+S 2

(3) llosever, if all of the thiosulfate were destroyed, the lodine release should be about equivalent to the non. additive release.

. This was not the case, and the degradation of the thiosulfate

• or the degradation products is assumed to actually promote the release of iodine from solution. .

---

..m.....,,,,,%,,,,,. . . _

\  ; ,

~

'N , ., .

.- /

=

i An unexpected result of this experiment was that about 11 to 15', of the iodine evolved was a penetrating form that passed through the 3 in. of activated carbon designed to collect the iodine. Some of this activity was Stopped in a 1-ft-thick backup bed of carbon, but a large portion penetrated it.

.redim ~;:!:a dfa:e + rocassim Hydroxide. To reduce possible-t

• acid decomposition of the thiosulfate. K0li (10-4!) was added to increase the preirradiation pil of the solution from "4 to >10.

( Some improvement was found in tha t iodine evaporation was reduced

. to 30%. The penetrating iodine was found again.

With the same K1 and K0li concentrations, the thiosulfate concentratic,n was increased to 0.1 wt '.. Almost quantitattve release of the iodine occurred, but there was no evidence of generation of the penetrating form. When the thiosulfato con-centration was increased to I wt ' with the same K1 and Koll concentrations, iodine evolution was significantly reduced to 0.044', in one experiment and 0.55', in another. There was no evidence of the penetrating fom.

The first of these experiments with KOH added indicates that the KOH served to partially neutrali:e the reaction product ( ll')

of Equation 2 thus reducing acid decomposition by Equation 3.

Ilowever, when the thiosulfate was increased to 0.1 wt '., the K0!!

was either ineffective in neutrali:ing the larger quantity of decomposition products (:ll') or was depleted in neutrall:ing the lower pit solution resulting from the larger addition of thlo-sulfate. In the case of the 1 wt ', addition of thiosulfate, sufficient thiosulfate was apparently present, even with decom-position, to maintain iodine essentially in the nonvapori:able lodide fom by 05:0* * + 1

• 5.0i" + 21* (4) t Pc:assiwi Ep.!r :f.!e. The alternatives to thiosulfate as an  ;!

• additive for f odine retention are limited. One that has been suggested is Koil. The rationale behind the use of K0ll is that it serves two purposes: 1) it promotes formation of the nonvolatile

. iodide by

• (5) 31:

• t>0ll*

• 51*

• 101 + 31120 and, 2) it increases solution pit to prevent the 011 radical attack 7

• of the iodidea : c Off* l' *1*Oll" (1) e e-

~.

which occurs in neutral or acidic solutions. In alkaline solution, the Oil r:dicals are diJsociated by the reaction sa 01

• ll* - + 0" (6)

The effectiveness of K0il as an additive was briefly examined.

With the same K1 concentration-as previously used, experiments were perforr.ed with K0li concentrations of 10-8M and g = 10-8M

13. 0 $ w t *.) . The iodine evolutions measured were 2.5 and 1.2%,

respectively.

A comparison of these rest.lts with the thiosulfate results indicates that 0.05 wt *. K0il is almost as effective as 1 wt %

thiosulfate. In addite.on, the change in iodine evolution is slighc for an almost 10. fold change in KOH; a 100. fold change in lodine evoin'.lon occurs for a 10. fold change in thiosulfate con.

centration.

The additive experiments are summari:ed in Table 7. Figure 3 shows iodine evolutJon as a function of radiation dose. '

. ..s..j.s .

.... i J

3

.i 4

. . .. s .a . . . :......s..

. f.

f .:*..s<, ,.c.::o ..s .:.

.: -ww y

/

/ .

l

'f. ... ... , . . s s .

,!. sve e j .)

- . . s .,:1

.... ..,.r. ,

l

, I

. .i 1

.r

3 3

l r --- T i . i . . . e v . .r

c. .....

FIGURE 3. Effec

• of Additive and Radiaticn Dose on todine .

Evaporation (5=10MSolutionofKI) .,

I '.

. 23 I g

t,

., .r, . ,n . , ,, ,. , g ,,9 y

~~...-.....-....~.~..-*.*.-*-~-

0

TABLE 7 lodine Evaporated Af ter Esoosure to 10' Rads

n:xnr uu t icne, '.'t1 g,p .

• D :e s.!wn t- lLi,

.'. 1 J 13 , W n .c.a ru t.,y No Additive 0.010 . - !4.0 d

Thiusul f.ste 0.010 0.014 - 94 0.010 0.014 - Oo#

Thiosul fate #

and K0li 0.010 0.014 0.006 30 0.010 0.1 0.000 'Jo 0.010 1.0 0.006 0.uJ4 0.010 1.0 0.000 0.55 K0!! 0.010 - 0.000 2.5 0.010 - 0.050 1.2

a. Expericents that gave the penetrating loden.. Species.

Fencerating Tom of Iodin.t 4 previously noted, several thiosulfate .idditivo esperiments produced significant quantities of an ludine f..rm capable of Tests were passing through several inches of setivated c sanon.

conducted to identify the penetrating icjane species :.nd to de.

' termine whether the species might be produced in systems (nat use activated carbon for removtng radiciodine.

Nine experiments were performed in the Co irradiation facility in an attempt to obtain a sample ot" ti.c penetrating lodine for analysis and identification. The esperimental equip.

ment shown in Figure 4 w.ts designcJ to freeze >ait a staple.

Nittor.cn was also substituted far air as the fltu gas to avoid free:ing out osygen. Af ter seven sa:!. esper.nents with KI and thiosult' ate concentrations equal to those that had previously given the penetrating lodine, the penetrating sodene was not forned in a nitrogen atmosphere. Oxygen apprears to be a pre.

requisite for its formation.

24

r o .-

.-e--- .-- w - - ~- - ~ ~ - - - " " ' ' - ~ ' " ~ ' ~ ~

. ...s.4.=*. n m .s . **. .

E shCut' y-- --O

___.__ _ _ _ _ _ _ _ _ _i_ _ _ _ ,

N4f 0*t'e .h I

?

, I s MYtt elef

, -n a < .

m . .*

r- !corC04 ad i Ig g

• Cold co:o

. ya 1 T'a t'a l r s...., U

/

-1 -

+7 r

Y m rrR eg'f,a I  !

( l cume ] ,

g

// W,K-t.

I i

II

,,,, y,,, y V@ .

vMe .==u, I i

i $ "o',7

• l I

w I HecJ l L_g__.._____. _____7 i P.ece co.aie,

_ Sta.nins i, ,,, ,,,.., e . g sini tous co.ain ci b( c

.- "co si. i

. V n__ . ,

w s D.

,W N

FIGURE 4 Schematic of todine Penetration Experiment i

Two experiments were then performed with flowing air and 's cc,ld trap containing dry ice and trichloroethylene ( "0'C) substituted for the liquid nitrogen trap. In both experimentn,

• the penetrating lodine was generated, but the trap was inc1pable

- of free:Ing out a tample. Two experiments were perforned . )

determine if the deccmposition products of thiosulfate ($3,* and 8 S) 6.cre involved in the femation of the p:netrating iodine.

One crperiment used K! plus NaA0. in the raJintion field and the c.ther used Ki plus sulfur. Neither experiment produced the penetrating forn of lodine.

Two additional experinents, with IIEPA filters in the air strevn, showed that the penetrating lodine was readily removable.

This rese' suggests that the penetrating iodine mav exist in '

the for:. sither a particulate Jr an aerosol. Both of these forms can pass through sctivated carbon beds. In the absence of

• a suitable :.nalytical technique to apply to the naterial collected oa the hila, identificatien work was halted.

- 25 -

t

p Conclusions The additive systems examined to date (with the exception of 1 wt t thiosulfate), do not greatly reduce iodine evolution from aqueous sclutions in an intense rajistion field. The 1 wt *. thio-sulfate additive offers the largest reduction but requires the largest amount of material.

A penetrating lodine species observed during the teste has not been identified. The present studies show that air is necessary for its formation and that thiosulfate in relatively low cor.centrations promotes its formation. Whether it is formed in the absence of thiosulfate is unknown. Although the decom-position products of thiotulfate did not promote the formation

, of the penetrating species in.these experiments, they may do so at a different pil.

e ' ae

%g l

O e

I

. c f,

O I

w

n

__n......

. . b.. . . . ..m.

. :< 3,- v: we . u: c=

APPEfiDIX - TEDA ANALYSIS Several possible analytical methods for determination of TEDA in carben were ir.vestigated. These included thermogravimetric analysit. differential thermal analysis, Kjeldahl nitrogen analysis, and solzent extraction followed by infrared abscrption analysis of the ext r.ct. The sniver.t extra. tion procedure proved most satis-factot> for analysis of the extract. The solvent extraction

• proce.!uce proved most satisfactory for analysis of new carbons.

The other methods either failed to provide specific TEDA content or lacked sensitivity for determining TEDA at the 120.1% level.

TEDA is dissolved from carbon in a Soxhlet extractor with CC1. as the solvent. In the absence of calibrated standards, carefully prepared laboratory-impregnated carbons were used to determine the extraction effic;ency (31.0 26.0% confidence inter-val). The TEDA content of the extract is determined with a calibrated infrared spectrophotometer. The infrared absorption band at 2880 cm** was chosen for determination of TEDA (see Figure A1) because the most reproducible data were obtained at this frequency.

Careful attention to detail is necessary to obtain reproducibic data with this method.

Carbcn, History The 2880 cm*8 (3.47 km wavelensti.) absorption band results from infrared absorption by carbon-hydrogen bands in the TEDA molecule. ..ny solvent-soluble hydrocarbon present as a contamit. ant in the carbon will interfere w .h the determination of TEDA; the <

metnod is tScrefore only useful for new charcoals which have not been exposed to organic chemical vapors. .

Sample Prepa-ation Water and dust must be removed frcm the carbon before TEDA c/ traction. The carbon dust and fines concentra* e in the er. tract alo.,g with the TEDA and decrease infrared transmission. Water, even in small quantities, also causes infrared interference. In

- addition, water deposits in the extraction solution remove some of the TEDA from the LC1. bec1use of preferential solubility in the aqueous phase. Dust can be renoved by blowing an air jet through a sample of the carbon suspended between two small, fine sieves (3-in.- series, 40 60 mesh).

27

._ _ ~

g- ' ,

• * ., r s a 1

~ ,

t

!' Wovile:qth, pm 4 5 6 7 8 5 10 2.5 3' '

i l 1 I I i. I -

-_( -

~

80 - '#C* p cct, '

b i

\ ~~

j J 6 60 -

{ '

E  !

t.

t j = ,

s -- i < > , s _

1

, j I

~

2 40 -

f b I

% 3 _2880 cm-' 1 EDA l-a e ccq --

Cotibration Peak

- (#

e l 20 -

.! l

~~

'#~

Tua ,Y. / ,

O 2000 .300 !L00 1400 (200 1000 -

! 4000 350C, 3000 2500 I Frequeecy, cm-' _

~

., FIGJRE A-1. Infrared Absorption of Spectrum of TEDA Extract

% /

w l

A 1

4 o

~~ -, __ ,,,

, ~ , . . . , . . . .

Drying the sample requ' ires considerable care. Three methods w"

were evaluated: heated drying, desiccant drying, and an intert gas purge. The mest consistent results were obtained whers a dry

' , . nitrogen purge at room temperature was used. TEDA losses into the dry nitrogen gas stream were not measurable (based on the lack of weight gain of a liquid nitrogen cold trap downstream of tb.

carbon drying chamber). Laboratory-prepared standards were dried in the same manner, so that all data are reported relative to nitrogen-dried samples.

• TEDA losses into heated air or nitrogen gas streams ranged from a 10'. loss in 2-1/2 hr at 100*C to quantitative loss (>99%)

in 2 hr at 140*C.

Desiccant drying was also unsatisfactory. Approximately

- 2 wt *. moistute remained in carbon samples stored in a desiccator over molecular sieves (Type 4A, predried at 600'C) for 96 hr.

Once dries'. in the nitrogen gas strea:n, carbon samples can be stored over molecular sieves in a desiccator without appreciable wight gain.

2 Because of the rapid absorption of moisture from laboratory l .

• air by dry arbon (>l ag/ min for a 2-g sample on a humid day),

rapid transfer and weighing techniques must be used. Although a

" dry. box" would be desirable to minimi:e moisture pickup during this phase of the oper:t'an, it was not found essential.

Sample Extraction - . . .

TEDA was dissolved from the carbon in a modified "Pyrez" micro extraction apparatus (Fisher Catalog 820-o30). Modifications included a larger boiling flask for larger solvent volumes and a wire mesh basket to contain the carbon sample.

' The sample is extracted for about 240 cycles (a cycle is the accumulation of a full extraction chamber of solvent in contact l

with the carbon in spectrographic-grade carbon tetrachloride

• 00 sCX-415 or SQ.2001). Spectrograde CCI. is required to minimi:e Intert'erence in the infrared measuremer.t. Ther=al degradation of TI:DA in the boiling flask was observed when cycle times were shortened be!m 45 seconds or when extraction tices longer than 3 i

'.ourt were used. Themal degradation is a function of the heating rate and the concentration of TEDA in the residual CC1. In the bolling flask (the concentration in this flask increases as the solvent is evsporated intc, the extraction chamber). Thus, the initial CC1. addition must be varied with the TEDA content to avoid exceeding a total TE0A concentration of about 1 mg/ml. An

! initial volume cf 20 ml of CLh was satisfactory for Type GX-16

~

- 29 l

he

{

\ '

t s .

\

t ps carbon (1% TEDA). 8 J0-m1. volume would be required for Type G-615 carbon (2% TEDA). Lt.rger boiling (1ssks may be requirel i for carbons containing 4-5'. TEDA. A therms! shiel.i extendin,.

-- ~~

> from the hot plate to the top of the extraction chamber was also found useful in avoiding thermal degrsoction. Lower heating rates could be used with the thermal shield beenuse it prevents air swept through the fune hood from cooling the apparatus.

Toxicity of CC1. precludes its use outside a fume hood.

When the extraction is complete, the extract is transferred

' with clean-CC1. washings, to a volumetric flask whose volune

, depends on the TEDA content of the carbon and the volume of solvent used in the extraction. For Type CA-176 carbon, a 25 m1 s flask was used.

1. Prec'autions must be taken in handling the finst solutions to av id evaporative tusses of CCi., which can occur even ti.reugh the ground glass stopper of the volu=ctric flask. If infrsaed analysis is inaticipated the same day as the extraction, an :ce l bath is reconmended. Overnight storsge should be in a refrigerstor. j Periodic cleanup of all glassware with chronic acid is also necessary to remove residust TEDA or TEDA degradation products.

Concentration Detenninations

• As noted earlier, the 3.74 .m wavelength shsorptions peak gave the most consistent data. A CsF: cell with a 1.0 mm path length was found necessary for the analysis because the less-expensive NsC1 cells fer,and retain TEDA. Careful cleaninr. of the cell after each determination is necessary to remove residual TEDA.

The spectrophotometer (a Perkin Elmers .bdct 5:1) was esli- l brated against samples of known concentrations of com=erci.1 TEDA .-

(98% purity). Three separate calibration runs were made, and a ,

• 1 east squares fit of the data points was esiculated tt obtain a

" standard" curve.

• The overall accuracy of the procedure is limited by uncer-

• tainties in the extraction cificiency but is estinated to be within s10% of the concentratien determined at the 90', confidence IcVel. Replicate determinations of the same carbon yielded values within slot of each other at the 93'. confidence IcVel, i

l .

j ,

i

, . . . . ~., -ve.>r<%

• rM j

REFERENCES 1.

W. S. Durant, R. C. Milham, D. R. Muhlbaler, and A. H. Peters.

Activity heactors.

Confiner ent Systers of the Savannah River Plant USAEC Report DP-1071. E. I. du Pont de Nemours and Co., Savannah River Laboratory, Aiken, SC (1966).

2. W. S. Durant.

Terfor":ance of Activated Carbon Bede in SAP

. Reactor Confinement Facilities - !Y:gress Report: Sepce~her

,~'.

JJC1 - Capte-lar 1Jff. USAEC Report CP-1028 e

E. I. du Pont de Nemours and Co., Savannah River Laboratory, Aiken, SC (1966).

3.

R. C. M 1 ham. High .**cnteratum Adscrhents for Iodine -

Progress Foport: January 1265 - Septerher 13tt. USAEC Report DP-1075 E. I. du Pont de Nemours and Co., Savannah River Laboratory Aiken, _SC. (1966) . .

4 R. C. Milham Stulies - Irogreseand L. R. Jones.

?eport: Iodine and Noble Gas Retention Catcher JJte .%:er-her lata.

USAEC Report DP-1009, E. I. du Pc.nt de Nemours and Co.,

Savannah River Laboratory Aiken, SC (1969). '

S.

R. C. Milhan Pr:;rees ?eport:snis'anuary

~ L. R. 12t3 Jones. Icdine Retention St. dies -

.i:o:e 1969. USAEC Report DP-1213, E. I. du Pont de Nemours and Co., Savannah ~ . r Laboratory, Aiken, SC (1969).

6.

R. C. Milham Pr:gress Eepcrt:and L. R. Jones. Icdine Retentien Studies -

'u:y 1963 - Dece~ler lit?. USAEC Repcrt DP-1234. E.1. du Pont de Nemours and Co., Savannah R8.ver Laboratory Allen SC (1970).

7. t, A. G. Evans and L. R. Jones. Iodine Retention Studies -

• !c Prs;ress Report: s cnuary 1970 - J:o:e 1370. USAEC Report A l DP-1259, E. 1. du Pont de Nemours and Co., Savannah River

• l Laboratory, Aiken, SC (1971). I l o 8.

! A. G. Evans and L. R. Jones. Icdina Retentien Studies -

Pr grees Report: Ju;y 1270 - :ece-ber 1973. USAEC Report DP-1271

- E. I. du Pont de Nemours and Co., Savannah River l Laboratory, Aiken, SC (1971).

9.

A. G. Cyans and L. R. Jones. Ccnfine ent of Airbone Radioactivity - Freircos Rep:rt: .anuary 1??1 s*<ne 1371. '

e USAEC Report DP 1280. E. I. du Pont de Nemours and Co.,

Savannah River Laboratory, Aiken, SC (1971). ,

{

10. A. C. Evans and L. R. Jones. Confine ~ent of Airbone .

l Radioactivity Erc3ress Report: July 1?71 - Dece-her 1371. \ -

USAEC Report DP-1295, E. I. du Pont de Nemours and Co.,

Savannah River Laboratory, Aiken. SC (1972). }

g l

i i '

1 l

E

11. A. C. Evans and L. R. Jones. C:nfir.c en: of Airbsme Radioactiv:'ty - Trogreae Repor: Janu:.rj 1972 - sur.e 1972.

USAEC Report DP-1316. E. I. du Pcnt de hemours and Co.,

Savannah River Laboratory, Aiken, SC (1973). .

r f l 12. A. G. Evans. Confinement of Airborne Radicactivity - ,

Progrees Esport: suiy 137: - :ece -l ar 1972. USAEC Report '

DP-1329, E.1. du Pont de Nemours and Co., Savannah River e Laboratory, Aiken SC (1973) . ,

'8- 13.

A. C. D.'=ns and L. R. Jones. Confine .en: of Airborne

) . Radioactivity - Ingress Fepart: Ja':uarj 1973 - J:o:e 1973.

}" ,

USAEC Report DP-1340 E. I. du Pont de Nemours and Co.,

Savannah River Laboratory, Aike.. SC (1973). ,

?

14 A. G. Evans and L. R. Jones. Confinement of Airborne Radioa:tivity - Prcgrees Report: suiy 1973 - Dece*:ber 1373.

USAEC Report DP-13SS, E.1. du Pont de Necours and Co.,

Savannah River Laboratory, Aiken, SC (1974).

IS. A. H. Dexter, A. C. Evans, and L. R. Jones. Confine ent of Airborne Radioactivity - Progresa Repor:: Januarj -

Dece.ber 1974. USEPA Report DP-1390, E. I. du Pont de Nemours and Co. , Savannah River Laboratory, Aiken, SC (197S).

16. D. A. Collias, L. R. Taylor, and R. Taylor. The revelop-cnc of Ir pwyna+ed Char:cais fcr Trapping No:hyt Icdide ac High R:eridity. UKAEA Report TRG 1300(W), (1967).

17. V. R. Diet: and C. II. Blachly. Activation of ;/ater SoZub!a A:-ince by Halogens for Trapping Radisiodine frors Airetrect.e.

USERDA-NRL Patent Application, Case N eer S-44,893 (1975).

18. V. R. Deltz, personal communiestion to A. C. Evans.

19. W. N. Bishop and D. A. Nitti, " Stability of 1hiosulfate Spray Solutions," ilue!. TechnoI. 13, 449 (1971).

4

20. ii. E. Zittel and T. II. Row, " Radiation and Ther. sal Stability

1. of Spray Solutions,' .'/ucE. Technol. 10, 436 (1971).

21. L. R. Jones. " Effects of Ra.11ation on Reactor Confinee.-nt System Materials." Tt elsh ..EC Air Cleaning Conference, Oak Ridge, Tennessee, August 28-31. 1972. USAEC Report CONF-720323 Volur.e 2 (1972).

4

22. A. R. Denaro and G. C. Jayson. Fundamentato of Radiation Chantis tes. Ann Arbor Science Publishers Inc., Ann Arbor, Michigan (1972).

p * * * ,