Bronze Alloy Development for Zinc Vapor Capture
- PDF / 1,770,690 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 7 Downloads / 179 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Bronze Alloy Development for Zinc Vapor Capture Paul S. Korinko
Submitted: 27 January 2017 / in revised form: 20 March 2017 / Published online: 24 April 2017 Ó ASM International 2017
Abstract After gamma-emitting 65Zinc was detected in a vacuum pumping system contained in a tritium glovebox, a series of experiments were undertaken to develop a method and material to trap zinc vapors in an area that is more suitable for preventing dose to workers. In this study, bronze alloys with 0–30% tin were prepared using a powder metallurgical process and exposed to three levels of zinc vapors. All of the alloys demonstrated acceptable zinc gettering capacity; however, low tin content bronzes are considered for further testing. Keywords Deposits
Radioactive contamination Zinc vapor
Background Gamma-emitting contamination of 65Zinc (Zn) deposits was detected in a vacuum pumping system after a thermal treatment of irradiated components that are used for tritium production [1]. Select deposits were analyzed, and it was determined that the source of the contamination was vapor deposition of small amounts of activated zinc from residual elements in the irradiated objects. The deposits were characterized for shape, formation, and adhesion as described in Ref. [1]. The results indicate that the 65Zn is derived from activated natural zinc and migrates as a metallic vapor [1].
P. S. Korinko (&) SRNL - MST, Builidng 773-A, Aiken, SC 29808, USA e-mail: [email protected]; [email protected]
123
As a result of conducting a number of experiments, a method to trap zinc vapors using filters that were heated to a specific temperature and placed strategically in the process piping was developed [2]. This solution, although effective for low tritium production rates, creates challenges at increased production rates since the gammaemitting zinc is captured in a glovebox that is designed to contain gaseous radioactive materials. Consequently, the facility operators desired a solution for this problem that is more compatible in an area of the facility designed for harder radioisotopes. This area has limited ability to change pressure and temperature profiles. To ensure the quality of the product, any material selected for evaluation could not absorb hydrogen and had to be otherwise compatible with the process. A comprehensive review of materials was conducted, and essentially, two alloy systems—copper and cobalt based—were compatible with the criteria [3]. Subsequently, a series of experiments was conducted to validate the usefulness of copper and commercial off-theshelf bronze materials [4]. While these materials were successful at capturing zinc vapor, they contain higher than acceptable levels of phosphorus, lead, or other species that are incompatible with the process and process gas [5]. Consequently, an alloy development program was undertaken to develop a binary alloy from pure powders. Powders were blended, compressed into pellets, sintered, and then tested for zinc capture in the appar
Data Loading...
