vii
15.7 15.8
Crack in t h e Core Outlet P i p e ..................................
15-9
Cutup of Loop and Preparation of Samples ..................................................................................
Oxygen Analysis ..............................................................................................................................
182 182
..................................................
184
15.10 Metallographic Examination ...................................................................................................
185
15.11 Isotope Activity Calculation from F l u x and Inventory History ..................................................
187
15.12 Isotope Activity Balance ............................................................................
..............................
190
.......................................................
190
15.13 Uranium-235 Observed in Graphite Samples .....................
15.14 Penetration of F i s s i o n Products into Graphite and Deposition onto Surfaces ........................
192
15.15 Gamma Irradiation of F u e l Salt i n t h e Solid P h a s e .....................................................................
193
.
PART 5 . MATERIALS DEVELOPMENT 1 6. MSRE SURVEILLANCE PROGRAM .....
.
17
................................................................................................
196
16.1
General Description of t h e Surveillance Facility and Observations on Samples Removed .......................................................................................
..............................
196
16.2
Mechanical Properties of t h e MSRE Hastelloy N Surveillance Specimens ..............................
200
GRAPI-IITE STUDIES ....................................................................................
.................
208
17.1
Mateiials Procurement and Property Evaluation ............................
208
17.2
Graphite Surface Sealing with Metals ............................................................................................
211
17.3
G a s Impregnation of MSBR Graphites ............................................
.........................
212
17.4
Irradiation of Graphite ......................
..........................................................................
18. HASTELLOY N STUDIES ..........................................................................................................................
215 217
18.1 Imprcivitig the R e s i s t a n c e of Hastelloy N to Radiation Damage by
............................................................................
217
18.2
Aging Studies on Titanium-Modified Hastelloy N ........................................................................
217
18.3
P h a s e Identification Studies in Hastelloy N ............
219
18.4
Hot-Ductility Studies o f Zirconium-Rearing Modified Hastelloy N ........
...............................
221
18.5
R e s i d u a l Stress Measurements in Hastelloy N Welds ..................................................................
223
18.6
Corrosion Studies ...................................................... ........................................................... File1 S a l t s ................................................................................................................ Coolmt S a l t s .................................................................................................................................... Equipment Modifications ............ ..............................................................................
226 226 227 230
18.7
Titanium Diffusion i n Hastelloy N ..........................................................
...............................
230
18.8
Hastelloy N-Tellurium Compatibility ............................................................................................
233
Composition Modifications ..........................
.............................................
19. GRAPHITE-TO-METAL JOINING .............................................................................................
........
236
19.1
Brazing of Graphite to Hastelloy N ................................................................................................ Joint Design ...................................................... .............................................. Brazing Development ........................................................................................................................
236 236 237
19.2
Compatibility of Graphite-Molybdenum t3razed Joints with Molten Fluoride S a l t s ..................
237