The diffusion of T in austenitic stainless steel, at temperatures above 373K, was found to be closely described by the equation:

D (cm2/s) = (4.7 x 10-3) m-½ exp[-12900/RT]

where m was the isotopic mass. Diffusion below 373K was greater than predicted by this equation, due to short-circuit and grain-boundary diffusion. Cold work, before or during exposure, significantly increased diffusion. Cold-working before exposure caused short-circuit diffusion through strain-induced martensite, while deformation during exposure led to enhanced transport by moving dislocations. Permeation through sheets was limited by surface absorption and was much less rapid than was predicted by the diffusion step alone. The solubilities were always lower than expected and were greatly dependent upon the surface conditions.

Tritium Absorption in Type 304L Stainless Steel. M.R.Louthan, J.A.Donovan, G.R.Caskey: Nuclear Technology, 1975, 26(2), 192-200

 

Table 63

Permeation of D through AISI 316

 

Temperature (K)

Pb-Li Layer

P (m3[STP]/smbar½)

518

yes

3.9 x 10-13

526

yes

4.1 x 10-13

526

no

6.8 x 10-13

540

no

2.7 x 10-13

547

no

1.0 x 10-12

548

yes

5.4 x 10-13

556

yes

6.0 x 10-13

556

no

1.2 x 10-12

570

yes

7.4 x 10-13

584

yes

1.1 x 10-12

586

yes

7.0 x 10-13

589

yes

9.0 x 10-13

589

no

2.3 x 10-12

600

no

3.0 x 10-12

625

yes

1.3 x 10-12

626

yes

1.3 x 10-12

626

no

4.2 x 10-12

629

yes

1.2 x 10-12

632

no

4.8 x 10-12

652

no

6.9 x 10-12

665

yes

2.0 x 10-12

667

yes

2.0 x 10-12

667

no

7.8 x 10-12

680

no

9.0 x 10-12