Future Directions in Tritium Removal and Cleanup

DOE-HDBK-1129-99

dC T

, at any time, t is

Therefore, the rate of tritium released from the system,

dC T

= LCT2(t) = LCT2(i)e -t(F/V)

where L = leak rate of the system

The tritium release from the system due to leakage T2(rel) over any time period from 0 to t, is

∫LCT2(i)e -t(F/V) dt

T2(rel) =

(V/F) LCT2(i)e -t(F/V) |t0

(V/F) LCT2(i)e -t(F/V)

The calculated leak rate that will result in a tritium release, T2(rel), of 1 Ci due to an initial tritium

release, CT2(i), of 1 g (10,000 Ci) into a glovebox with a volume, V, of 1m3 and a flow rate, F, of

1m3/min is

T 2(rel)/(V/F) CT2(i)e -t(F/V)

1/ (1 x 10000 x 1)

.0001 m3/min

1.667 cm3/s

Therefore, a glovebox leak rate of 1.667 cm3/s will result in the release of 1 Ci of tritium from a

1 m3 volume glovebox during the time it takes a tritium removal system operating at a flow rate of 1

m3/min to clean up the glovebox following a tritium release.

4.1.3 Future Directions in Tritium Removal and Cleanup

Future tritium facilities should analyze the applicability of confinement systems in their facilities.

For example, DOE O 420.1, Change 2, states, "For a specific nuclear facility, the number and

arrangement of confinement barriers and their required characteristics shall be determined on a

case-by-case basis. Factors that shall be considered in confinement system design shall include

type, quantity, form, and conditions for dispersing the material. Engineering evaluations, trade-

offs, and experience shall be used to develop practical designs that achieve confinement system

objectives. The adequacy of confinement systems to effectively perform the required functions

shall be documented and accepted through the Safety Analysis Report."

As regulatory release criteria and ALARA concerns are strengthened, the desirability of barriers

increases. Most current confinement systems are of the glovebox and of the room or building

cleanup types. One disadvantage of these current designed systems is that tritium is converted to

oxide, which eventually must be handled and disposed (with the attendant risks). Room or building

type confinement systems are used in some tritium facilities such as in the T-building at Mound, in

TFTR at Princeton Plasma Physics Laboratory, and in TSTA and WETF at Los Alamos. If the

system is not very close to 100% efficient, the released oxide (which is ~ 25,000 times more toxic

than the gas) could give an overall detriment (e.g., if 25,000 Ci of gas are collected, but only one Ci

of oxide is released by the system, the whole operation is just a draw). Some current designs,

notably the cleanup systems at RTF, make use of gettering without oxidation. Additionally,

research efforts for other systems that replace the oxidation step are active in the DOE complex.

The primary advantage of these getter systems is that tritium is removed and stored in elemental