HFIR Pressure Vessel and Structural Components Materials Surveillance Program

A proposal has been made to increase the size of the HFIR HB-2 and HB-4 beam tubes and to extend the life of the vessel to 50 EFPY(100 MW). Studies indicate that the increase in radiation-induced embrittlement of the vessel can be tolerated, and an appropriate expanded vessel-materials surveillance program has been devised. This program, which is the subject of this report, includes additional beam-tube nozzle-material surveillance specimens, relocation of existing specimens of all materials, and additional dosimetry. As an aid in the placement of specimens and dosimeters, extensive two- and three-dimensional neutron and gamma flux/dpa transport calculations were made. Surveillance data will be added to the HFIR vessel (delta)NDTT vs dpa data base, and dosimetry will be used to normalize the calculated fluxes. The updated (delta)NDTT vs dpa correlation and the normalized dpa values will be used in the calculation of the probability of vessel failure. This procedure, in conjunction with periodic hydrostatic proof testing, is used to determine the useful life of the vessel.