TRITIUM STORAGE DEVELOPMENT 

PROGRESS REPORT NO. 10 

OCTOBER-DECEMBER 1976 

Prepared for the 

NUCLEAR FUEL CYCLE AND PRODUCTION DIVISION 

UNITED STATES DEPARTMENT OF ENERGY 

WASHINGTON, D.C. 20545 

r PROCESS TECHNOLOGY DlvlsloN 

I 

DEPARTMENT OF NUCLEAR ENERGY 

I\ BROOKHAVEN NATIONAL LABORATO 

I 

I ASSOCIATED UNIVERSITIES, INC. 

CONtMtZ NO. EY-76X424016 Wm( +a*.- -. 

-. r I UNITED STATES DEPARTMENT OF ENERGY 
DISCLAIMER 

This report was prepared as an account of work sponsored by an 

agency of the United States Government. Neither the United States 

Government nor any agency Thereof, nor any of their employees, 

makes any warranty, express or implied, or assumes any legal 

liability or responsibility for the accuracy, completeness, or 

usefulness of any information, apparatus, product, or process 

disclosed, or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial product, 

process, or service by trade name, trademark, manufacturer, or 

otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any 

agency thereof. The views and opinions of authors expressed herein 

do not necessarily state or reflect those of the United States 

Government or any agency thereof. 
DISCLAIMER 

Portions of this document may be illegible in 

electronic image products. Images are produced 

from the best available original document. 
BNL 50728 

U C-70 

(Nuclear Waste Management - TID-4500) 

TRITIUM STORAGE DEVELOPMENT 

PROGRESS REPORT NO. 10 

OCTOBER-DECEMBER 1976 

PETER COLOMBO. Project Head 

M EYER STEINBERG, Division Head 

Contributors: 

P. Colombo 

R. Johnson 

M. Greene 

J. Reilly 

R. Wiswall. Jr. 

NOTICE 

mi report was prepared as an account of work 

sponsored by the United Statco Covemmcnt. Nrithcr the 

United States nor Le United States Department of 

Enerw, nor any of their employees, nor any of their 

u~~~ina~tu,;, oubaontmoton, nr lhrir cmplov~~~, mpkcs 

bay warrsnty, ervssu Illlpl;il, 8, nr?l~mn* an)# lrgal 

liability or responsibility for the accuracy,completcncsr 

or uvfvlnen of any informtion, apparatus, product or 

proce5 dircloxd, or reprewnU that its ux would not 

infringe privately owned tighu. 

PROCESS TECHNOLOGY DIVISION 

DEPARTMENT OF NUCLEAR ENERGY 

BROOKHAVEN NAT'IONAL LABORATORY 

UPTON, NEW YORK 11973 
This report was prepared as an account of work sponsored by the United States 

Government. Neither the United States nor the Unitcd States Depart~~~clit of Energy 

(DOE), nor any of their employees, nor any of their contractors, subcontractors, or 

their employees, makes any warranty, express or implied, or assumes any legal liability 

or reoponolblllt)~ for the accuracy, coi~~~lec~~~ess UI uscful~~ess ofany Information, 

apparatus, product or process disclosed, or represents that its use would not infringe 

privately owned rights. 

Printed in the United States of America 

Available from 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

Price: Printed Copy $4.00; Microfiche $3.00 

December 1977 400 copies 
. . 

Table of Contents 

Introduction 

Summary 

Page 

I. Tritium Storage in Metal Hydride 1 

. A.' ~~drogen-~etai Reaction Studies 

B. Engineering Scale Studies - 4 

11. Preparation of Polymer-Impregnated ~ritiated Concrete by - -- " 

the Injector Method 12 

References 15 

~istribution List 

List of Tables 

1. Experimental Hydriding of Zirconium 3 

List of Figures 

1. Low-Pressure Glass System for Hydriding Studies. 2 

2. Metallograph of Hydrided Zirconium Rod Sample No. 9. 5 

3. Metallographs of Nonhydriding Zirconium Sponge and Hydrided 

Sponge Sample No. 3. 6 

4. Scanning Electron Micrographs of Nonhydrided Sponge and 

Hydrided Sponge Sample No. 4. 

5. Container for Tritium Storage in Metal Hydride for Use with 

Small Size Reaction Metal. 9 

6. Container for Tritium Storage in Metal Hydride for Use with 

Large Size Reaction Metal. 9 

7. Conceptual Fixation of Aqueous Waste in Polymer Impregnated 

Concrete by the Injection Technique. 13 

8. Fixation of Aqueous waste in Polymer Impregnated Concrete by 

the Injector Method. 13 

9. Injector Technique for the Fixation of Aqueous Wastes in 

Polymer Impregnated concrete. 

- iii - 
INTRODUCTION 

. . . . 

The goal .of this is the development of a process for the conirersion 'of tritium waste' into a chemically and physically stable solid form. 

The major portion of the work to date at Brookhaven National Laboratory (BNL) 

has been on the fixation of tritium in concrete suitable for burial. '~nasmuch 

as the polymer-impregnated tritiated-concrete method has been developed into 

a workable process, the technology is now being transferred. to Mound Laboratory 

for a full scale demonstration, A low-level effort in 'this 'area will be' 

maintained at BNL to continue the transfer of this technology and complctc . .. 

some of the developmental studies. A new phase of this program has been 

initlatea to demonstrate a process for the fixation of trPtium as a tritide 

in a stable metal hydride. It is well known that some metals can absorb 

large quantities of hydrogen by reaction to form hydrides. Preliminary leach 

studies at BNL indicate zirconium to be suitable for further investigation as 

a potential substrate material. 
. . SUMMARY 

Laboratory and engineering scale work has been initiated on the storage 

of tritium in a metal hydride. Laboratory hydriding apparatus has been 

assembled and a preliminary series of experiments was carried out on zirconium. 

Several engineering design concepts for the reaction and storage of tritium in 

a metal hydride are presented. The design of a three (3) inch diameter 

bench scale reaction system is in progress. Developmental work is continuing 

on' the injector technique for the fixation of tritium in polymer impregnated 

concrete . 
I. TRITIUM STORAGE IN METAL HYDRIDE 

A program has been initiated to demonstrate a safe and economical process 

forthe fixation of tritium as a tritide in a metal hydride. For tritium 

absorption and retention purposes, zirconium appears to be most desirable 

although alternatives such as Ti, Hf, V,Nb and certain alloys of these can* -. 

also be used. The choice of zirconium as the leading candidate metal for 

this study is based on its @own properties and on the chemica1,and physical 

properties of the hydride. The process can be reversed, if desired, by 

heating the hydride above its decomposition temperature (defined as' 'the 

temperature at which the hydride dissocj.ation pressure is above 1 atm) and 

collecting the evolved gas. While the fixation process will be deve1bpe'd 

for long term storage or disposal by burial, retrxevability of the tritium 

will be considered for future needs such as for use in controllbd'thermonuclear reactors. 

A. Hydrogen-Metal Reaction Studies 

A glass system was designed and fabricated as shown in Figure 1 for conducting the initial hydriding studies at pressures below one atmosphere and 

up to 900~~. Measurement of pressure, volume, and temperature permit the 

extent of hydriding to be followed continuously. 

A preliminary series of hydriding experiments were conducted using 

zirconium metal and hydrogen gas. The experiments were designed mainly to 

establish operating procedures and working parameters for the engineering 

scale studies. Specimens of both pure and commercial grade zirconium metal 

were prepared from foil, rod, and sponge for this study. The '~rocedure was 

- 4 

to outgas the specimen for one hour at 700° in a good vacuum (10 to . .. 

torr) and then hydride at'a controlled temperature between 600 and 900~~. 

Table 1 summarizes some of the results obtained. 

The hydride reaction proceeded smoothly and at adequate rates. Even 

the thickest specimen, the 1/2 inch rod (sample No. 61, went to composition . . . . 

ZrH1.8 in four hours at 600~~. It cracked, however, as did most of the bar 

stock specimens. The sponge on the other hand appeared to retain much of 

its strength and was free of visible cracks.. The rate of hydrogen uptake 
VESSEL 

STATION I . STATION ,3 

i:. ' 

~i~hrel- 1. : LO"-pressure glass system for hydriding studies. I' . . , ,. 
TABLE 1 

Experimental Hydriding of Zirconium 

Sanple 

N3. 

Weight, Hydriding Hydriding Press. , torr H/Zr atom Time, 

9 Temp, OC Initial - Fmm Final Ratio (a) Min Notes 

1/4" rod .. 1.61 230 cracked (b) 

1.88 240 cracked 

1.90 7 no change 

1.87 15 no change 

1.83 3 0 cracked 

1/4" rod 

sponge 

sponge 

1/16" foil 

1/2" rod 

1/4" rod 

1/4" rod 

245 cracked (brc) 

185 cracked (brc) 

210 cracked (C 

9 1/4" rod 2.8007 7 65 280 44 intact ('? 

10 1/4" rod, . 2.6842 725-804 152 230 cracked (btc') 

11 1/4" rod 2.8169 723-816 463 239 1.67 340 cracked (C ) 

' 12 . . 1/4" rod 3.0350 900 478 329 ' 1.10 . . 55 . intact(c.) r- . . . . 

13 . ' sponge , . 5.8538 900 730 431 , 1.50 130 . no change(c) 

:a)Atom ratio determined by weighr gain. 

'b)System recharged with hydrogen during run. . , .. . 

IC) ~~drbrgen added in ' &all volume increments. : 
by the sponge was observed to be much greater than for bar stock. One 

specimen (No. 3) went to ZrHl 6 in seven minutes at 600%. 

~hree of the specimens (NOS. .3, 4, and 9) were subjected to metallurgical 

examination. A metallograph of hydrided commercial grade zirconium 1/4 inch 

rod, sample No. 9 (Figure 2) indicates extensive cracking and void formation 

even though the specimen remained intact at the completion of the run. In 

Figures .3 and 4, non-hydrided and hydrided sponge may be compared; a change 

in structure is evident, with an appreciable increase in void size appa'rent 

in sample No. 3 (Figure 3). 1t was determined that outgassing did not significantly effect the structure of the sponge. A nnn-hydrided polished 

sponge specimen was maintained at 700°c for one hour - in - vacuo. -. No measurable 

volume of gas was collected and the weight remained unchanged. Microscopic 

examination showed no change in appearance. , 

Qualitatively, sponge meterial seems more attractive both from a cost 

and strength viewpoint. However, the increased surface area to volume ratio 

may possibly result in higher leachability. . . 

. . B. Engineering Scale Studies 

An engineering scale study of the storage of waste tritium as a tritide 

in a metal hydride has been initiated. This process is heing designed to 

treat concentrated tritium effluent. from the Mound Laboratory isotope exchangel. 

The developmental work at BNL, however, will be limited to operation with 

tracer quantities of tritium. The final "hot" demonstration will subsequently 

be carried out at Mound Laboratory. 

In this process, tritium and hydrogen gas produced electrolytically 

from enriched tritium effluent is fed into a reaction system containing a 

reaction metal such as zirconium maintained at the required temperature and 

pressure. After reaction is completed, the metal tritide-hydride product is 

removed and placed in a suitable shipping container. Although permanent 

storage or burial is the immediate and primary concern in this program, 

retrievability of the tritium, such as for evcntual use in controlled thern~onuclear reactors should also be considered. A need also exists for safe and 

efficient transport systems, as well as for short-term storage in tritium 
I. No. 9. 
Nonhydrided Zirconium Sponge - 300 X 

-- - Hydrided Zirconium Sponge - 300 X 

Figure 3. Metallographs of nonhydriding zirconium sponge 

and hydrided sponge sample No. 3. 
W.nrrhydriod sponge - 200x 

Figure 4. Scanning electron micrographs of nonhydrided 

sponge and hydridcd sponge sample No. 4. 
processing systems. 

An evaluation of the product stab~lity is of primary importance in the 

design of the shipping container and storage system from the standpoint of 

safety and tritium retention. Extensive testing is planned and will include 

leach studies, mechanical and physical testing, thermal stability, chemical 

stability, thermal conductivity, radiation resistance, and pyrophoricity 

studies. 

Minimal containment of the product for shipping and storage is required 

if it is sufficiently stable. However, severe degradation could necessitate 

further treatment such as encapsulation in cement or polymer- Of course, the 

type and extent of containment and treatment needed is also dependent on 

whether retrievability of the tritium is desired. Burial of the waste product 

would require low leach rates, and low cost containment would be advantageous 

from an economic viewpoint. Inasmuch as the design of the storage system, as 

well as the reaction system,is dependent on the storage option selected 

(retrievability, interim storage, burial, etc.), the overall process must be 

taken into account in any design. 

A preliminary design concept in which the same vessel is utilized for 

reaction and storage is shown in Figure 5. This vessel. wn11ld he designed 

to withstand the temperature and pressure of the hydriding operation, as 

well as pressure buildup due to helium decay product formation. Metal that 

is to be reacted is loaded into the vessel through the top opening, which 

also serves as the feed gas inlet, into which there is inserted a sintered 

metal filter and valve. A filter is required to prevent discharge of tritide 

fines out of the reaction storaqe vessel" Aftex the reactinn is nnmpl~ted, the 

valve is shut off and the container is capped for shipment. If retrievability 

of the tritium is not desired, the valve and shipping cap may be omitted and 

the container may simply be sealed with a plug and serve as either a burial 

container or be emptied after shipment and reused in the process. 

On the basis of earlier preliminary laboratory work at BNL (1-3) and 

Battelle Northwest lab~ratiries(~', the reaction metal could be zirconium or 

Zircaloy in the form of 1/4 inch diameter rod or 1/2 inch diameter tubing cut 
REACTION 

METAL 

Figure 5. Container for tritium storage in metal hydride 

for use with small size reaction metal. 

CONNECT ION 

Figure 6. Container for tritium storage in metal hydride 

for use with large site reacLlo~l ntetal. 
into 1/2 to 1 inch long pieces. The void,volume for solid cylinders in a 

random packed bed for low particle diameter to vessel diameter ratios is 

approximately 33%. For higher ratios and hollow cylinders or tubing, the 

void volume is greater, of course. Because of expansion of the metal during 

tritide-hydride formation which could severely buckle and weaken the reaction ~r 

vessel, an allowance of approximately,20% additional void volume must be made. 

The void volume can be reduced with an ordered bed system, especially 

for certain geometries. Minimum void volume is possible with a single'large 

piece of reaction metal sized to fit the rea~Liun vessel less whatever 

allowance is needed for expansion during reaction. In other than a very 

small system, the reaction time could be excessive and severe physical degradation of a more massive piece by cracking and reduction to fines could be 

a problem. This, of course, will have to be determined by laboratory studies. 

Minimum void volume without the possible problems of excessive reaction 

time and degradation can be obtained with plates or discs the size oE the 

reaction vessel (less an expansion allowance) stacked one on top of another. 

If need be, spacers can be used to permit undisturbed flow of feed gas to 

the metal surfaces. In addition to minimum void volume, good heat transfer 

rates for the removal of heat of reaction are possible in this system because 

of the higher thermal conductivity of the metal plates as compared with a 

bed of slugs or particles wherein heat transfer is mainly by gas phase conduc tioil. 

The use of massive pieces or large size plates would necessitate a 

vessel of a design that would permit their loading. One possible design is 

ulwwn in Figure b in which the top is welded in place after the container 

bo been loadd. An engifieering study is needed to determine the feasibility 

anB economics of this system. 

The use of scrap 2i;ircaloy and irradiated Zircaloy fuel cladding hulls 

has been suggested(4) to increase the economic favorability of this process. 

Compacted spent cladding hulls would be more readily accommodated in a vessel 

of the type just described, but the presence of long lived actinides in the 

cladding hulls would of course create additional problems. Unfabricated 
lower cost metal such as zirconium sponge would also increase the economic 

favorability of the process. 

The design of a three inch diameter bench scale reaction system is in 

progress. A preliminary engineering scale evaluation of the candidate metals 

will be carried out in this system. 
11. PREPARATION OF POLYMER-IMPREGNATED TRITIATED CONCFtETE 

BY INJECTOR METHOD 

While the end-over-end drum tumbling method has been pursued to date and 

developed to a workable form, it is desirable to produce polymer impregnated 

tritiated concrete (PITC) by a technique which is more directly compatible 

with the glove box operations in use with high-level tritiated aqueous waste. 

Development of such a technique using an injector to distribute the aqueous 

tritiated waste in dry cement is continuing. 

A schematic diagram of the injector technique is shown in Figure 7. In 

this process, the cement casting container is filled with dry cement and compacted by vibration. The injector, which is simply a hollow tube containing 

several orifices along its length through which the aqueous waste is dispersed, 

is inserted into the dry cement. Tritiated aqueous waste is then introduced 

into the cement through the injector. Aqueous waste is added to the cement 

until the waste reaches the external surfaces of the cement as evidenced hy 

dampness. The injector is withdrawn and the cement casting is allowed to 

cure. After the casting has cured, catalyzed styrene monomer is introduced 

into the casting container and allowed to soak through the composite. After 

the casting has been completely permeated by the monomer, the monomer is 

thermally polymerized. Subsequent to the waste injection, this grQcess i~ 

the same as the previously developed end-over-end drum t~lmbling method. 

As shown in Figure 8, this process does not produce a homogeneous composite. Rather the aqueous waste content is higher near the centerline of 

the composite coincident with the injector and decreases as the surface is 

approached. The polymer loading, however, is highest near the sprface of I 1' 

Ll~e cu~nposire anu decreases as the centerline is approached, although polymer 

is present throughout the composite. This effectively encapsulates the waste. 

An apparatus fox producing PTTC hy this teahniquc 13 shown i11 Fiqurt! 9. 

Polymer-impregnated specimens containing nontritiated water are being 

prepared by the injector technique to optimize the procedure for preparing 

PITC specimens to be leach tested at the Savannah River Plant. In addition, 

concrete and polymer reinforcement materials and polymer additives are being 

investigated. Specimens with wire mesh, glass fibers, and glass fiber cloth 

have been prepared and are being evaluated. 
Dry Cement 

Aqueous 

Waste 

Ca talyced 

Monomer 

I. CONTAINER FILLED WITH 2. IN JECTlON BEG U N.AQUEOUS 

DRY CEMENT: WASTE IN- WASTE DIFFUSES INTO DRY 

JECTOR INSERTED. CEMENT THROUGH INJECTOR 

PORTS. 

3. AQUEOUS WASTE DIFFUSES 4. AFTER IMPREGN4TlON. THE 

THROUGH THE CEMENT. POLYMER LOADING OF THE 

THE WASTE CONTENT IN COMPOSITE IS HIGHEST AT 

THE CEMENT DECREASES THE CASTING SURFACES. 

AS THE CASTING SURFACES EFFECT! VELY ENCAPSU ~ATING 

ARE APPROACHED. THE WASTE. POLYMER IS 

Cement 

Cure 

Waste 

Injection 

PRESENT THROUGHOUT THE 

COMPOSITE. 

Contamer + Filling 

- - 

T 1 ' 

Figure 8. Fixation of aqueous waste in polymer impregnated 

concrete by the injector method. 

Contalner 

Vibration 

Thermal 

Polymrr- - 

ization 

+ 

Disposal 

Injector 

Insertion 

- -- 

Figure 7. Conceptual fixation of aqueous waste in polymer 

impregnated concrete by the injection technique. 

Soak 

Impregnation 

- 
CATALYST 

/ADDITION H 

RESERVOIR RESERWI R 

VALVE SHUTVALVE 

Figure 9. Injector technique for the fixation of aqueous 

wastes in polymer impregnated concrete. 
References . . 

1. Colombo, P., et. al., "Tritium Concentration and Fixation", Progress 

Report January-March 1974, BNL 18879. 

2. Colombo, P., et. al., "Tritium concentration and Fixation", Progress 

Report April-June 1974, BNL 19303. 

3. Colombo, P. , et. a1 . , "Tritium Storage ~evelo~ment" , Progress Report 

April-June 1975, BNL 20421. 

4. Seheele, R.D. and L.L. Burger, "Zirconium Hydride as a Storage Medium . ,. ..-:- 

for Tritium", BNWL 2083, July 1976. .,, .. . ,. . 

. , 

. . 
- 

DISTRIBUTION LIST 

B.C.. Musgrave . . ' 

Allied Chemical Corporation 

550 Second Street 

Idaho Falls, Idaho 83401 

A.K. Williams 

Allied General Nuclear Services 

Barnwell, South Carolina 29812 

Martin Steindler 

Argonne National Laboratory 

9700 South Cnss Avenue, Bldg. 205 

Argonne, Illinois 60439 

L.E. Trevorrow 

Argonne National Laboratory 

9700 South Cass Avenue 

Argonne, Illinois 60439 

R.I. Newman, Vice President 

Barnwell Nuclear Fuels Plant 

Allied-Gulf ~uclear Services 

P.O. Box 847 

Barnwell, South Carolina 29812 

L.L. Burger 

Battelle Northwest Laboratories 

325 Building 

Richland, Washington 9935'2 

Victor Benaroya, Chief 

Effluent Treatment Systems Branch 

Directorate of Licensing 

Department of Energy 

Washington, D.C. 20545 

P.E. Coffman 

Division of Operational Safety 

Department of Energy. . . washington, B.C. 20545 

John C. Dempsey 

Development Branch 

Division of Nuclear Fuel Cycle and Prod. 

Department of Energy 

Washington, D.C. '20545 

W.H. McVey, Chief 

Fuel Cycle Branch 

Division of Reactor Research 

and Development 

Department of Energy 

Washington, D . C . 20545 

N. Thomasson 

Environmental protection Agency 

401 M Skeet, S.W., Koom 91U 

Washington, D.C. 20460 

L.T. Lakey 

Exxnn Nuclear Company 

2101 Horn Rapids Road 

Richland, Washington 99352 . 

G. Winsor 

Manager Safetyand Analytical Ser. 

Midwest Fuels Recovery Plant 

Morris, Illinois 60450 

M. Barbier 

Mitre Corporation 

1820 Dully Madison Avenue 

McLean, Virginia 22101 

George Abell. . 

MQ~sXI~O Resea.rch Corporation 

Mound Laboratory 

Miamisburg, Ohio 45352 

C. J. '~ershner 

Monsant.0 Reseaxch Corpoxation 

Mound Laboratory 

Mia~~Psburg, O-Mo 45352 

Emkl Mershad . . 

.Monsanto Research Corpo~nt.i on 

Mound Laboratory 

Miamisburg, Ohio 45352 

C.A. Burchsted 

Oak Ridgc National Labrsrdtory 

P.O. Box X . 

Oak Ridge, Tennessee 37830 
DISTRIBUTION LIST . (Continued) 

Hersche1.W. Godbee 

Oak Ridge National Laboratory 

P.O. BOX X 

Oak ~idge, Tennessee 37830 

E.H. Kobish 

Oak Ridge National Laboratory 

P.O. Box X 

Oak Ridge, Tennessee 37830 

K.H. Lin 

Oak Ridge National Laboratory 

P.O. Box X 

Oak Ridge, Tennessee 37830 

E.C. Choi 

Ontario Hydro 

700 University Avenue 

Toronto, Ontario 

M5GlX6 Canada 

R.H. Hawkins 

Savannah River Laboratory 

Bldg. 735A, Room B123 

Aiken, South Carolina 29801 

D.A. Orth 

Savannah River Laboratory 

Bldg. 773-A, Room 117 

Aiken, South Carolina 29801 

D.T. Pence 

Science Applications, Inc. 

1200 Prospect Street 

P.O. Box 2361 

La Jolla, California 92038 

J. J. Cohen 

University of California, Lawrence 

P.O. Box 808 

Livermore, California 94550 

BROOKHAVEN NATIONAL LABORATORY DISTRIBUTION 

Manowitz , , 

Steinberg 

Colomho 

Johnson 

Neilson, Jr. 

Becker 

Belkin - DOE 

Schweller - DOE