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Kuppusamy, M.V.
- Qualification of Critical Weld Joints for Dynamically Balanced Nuclear Component
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Affiliations
1 Quality Assurance Division, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102, India, IN
1 Quality Assurance Division, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102, India, IN
Source
Indian Welding Journal, Vol 55, No 2 (2022), Pagination: 54-62Abstract
Centrifugal extractors (CE) are widely used in reprocessing of spent fuel of fast breeder reactors due to various advantages. The extraction is carried out from a solution of 4-6N nitric acid, organic compounds, and elements containing fission products. Centrifugal forces generated from the rotating bowl (RB) are utilized for this purpose. RB is a thin hollow shell with complex internals. It rotates along a longitudinal axis inside a stationary bowl by maintaining a minimal specified annular gap ranging 3-5 mm during operation. A high-grade dynamic balancing is essential for each fabricated RB to keep generated vibrations within limits of safe operations. The Cylindricity of RB is controlled up to 0.1 mm and a surface finish of N8 is maintained for many reasons including the requirement of dynamic balancing. Despite maintaining all parameters, it is sometimes observed that a considerable quantity of fabricated RB gets rejected due to the non-feasibility of possible corrections during dynamic balancing of fabricated RB. The post-weld examination of internal surfaces is difficult and any type of post-weld repair of fabricated RB remains unproductive. A welding procedure has been adopted during manufacturing of AISI 304L material, 40 mm ID x 1.5 mm (thk) RB with specified dynamicbalancing requirement of grade 2.5 as per ISO1940-1 (2003) at 3500 RPM and corrosion rate of a maximum of 15 mills per year as per practice C of ASTM A 262. The welding procedure qualification has been carried out using gas tungsten arc welding (GTAW). The welding variables such as groove design, heat input, welding position, welding sequence, fixtures, clean fit-up, etc are found as important to monitor apart from other commonly used to meet the acceptance criteria as per ASME sec IX.Keywords
Welding Qualification, Dynamic Balancing, Corrosive Environment, Nuclear ReprocessingReferences
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