NSUF EBR-II-HEXBLOCK: EBR-II Legacy Hexblocks and Assemblies

The HEX-BLOCK inventory is composed of two major parts. The most accessible part for future research was derived from an EBR-II reflector assembly designated U9807 that has been extensively disassembled with various portions of the inventory residing at two locations, Westinghouse-Pittsburgh and Idaho National Laboratory. The second, much larger part of the inventory resides only at Idaho National Laboratory, but has not been disassembled, requiring significant funding and effort to render them available for further research. This second part of inventory is comprised of five complete EBR-II reflector assemblies, U9902 from Row 9, and assemblies U9005, U9006, and U9027 from Row 10. Reflector U9027 was fabricated with a 12% cold-worked Type 316 steel can and Type 304 steel blocks, while the other four assemblies had Type 304 steel cans and blocks. See the attached documentation describing these five assemblies. For a description of the general features of the hex-blocks in each of these assemblies, see the reports describing the disassembled assembly designated as U9807. Additionally, see the compiled publications resulting from various studies on U9807. The U9807 assembly was originally composed of a stack of 5 hexagonal cross-section 304 SS blocks contained in a thin-wall (1 mm) hexagonal 304 SS wrapper duct located in row 8 of the EBR-II fast reactor in contact with sodium flowing between the blocks and the wrapper duct. Each block had dimensions of ~52 mm flat-to-flat cross-sectional thickness and 218-250 mm length, with the length depending on the individual block. Block 1 at the bottom of the assembly was discarded as waste upon disassembly. During their in-core residence the U9807 blocks spent about four-and a-half years (~54 months) in row 8 and were then parked in row 16 for about eight years (~96 months). The largest fraction of the dose (~97%) was accumulated in row 8 before the middle of 1986 and the assembly was discharged from the reactor in late 1994. The five blocks accumulated ~0.4 to ~33 dpa depending on their axial and radial position in the block assembly, with the highest doses experienced on the inboard core-facing side of the assembly. Significant axial and radial gradients in dpa rate, temperature and gamma heating, with the latter leading to significant internal temperature increases, developed over the stack of five blocks, producing a complex internal spatial distribution of void swelling, thereby leading to measurable macroscopic distortion of the blocks. Two of the five blocks, namely, block 3, positioned at mid-core height and experiencing the maximum neutron exposure, and block 5, positioned well above the core at much lower neutron exposure were selected for destructive examination, specifically to allow identification and separation of two concurrent but opposite strain contributions arising from void -related swelling and carbide precipitation-related densification. As a result of cutting, blocks 3 and 5 have been rendered into a large collection of various size specimens ranging from TEM disks, thin plates, cm-size cubes and various larger sizes, all suitable for immediate access and examination. While small portions of this inventory have been shipped to various National laboratories and universities, the largest portion of this inventory is located at Westinghouse-Pittsburgh. All portions of this inventory have assigned temperatures, displacement doses and calculated helium levels. The remaining two blocks (2, 4) from U9807 reside at INL and are available for studies requiring larger volumes of material. Some limited profilometry data is available and displacement doses and temperatures can be generated from available information.

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필드	값
Award Announced Date	2024-01-16T09:40:11.353
Awarded Institution	None
Facility Tech Lead	Alina Montrose, Yaqiao Wu
Irradiation Facility
PI	None
PI Email	[email protected]
Project Type	RTE
RTE Number	None