Session: 10-03: Advanced Manufacturing 3

Paper Number: 135340

135340 - Joining Fuel Rod to End Cap W/ No Flaw. Repeatable. 

Abstract: 

Joining fuel rod to end cap w/ no flaw concept was presented to ICONE30 Kyoto 2023.

Fuel rod to end cap, either induction, laser or GTAW are joined at the shoulder globally w/ HAZ, residual stress and uncertainty. And as much as quality and process has improved dramatically, industry have not delivered 100% flawless welds. Inspection and re-inspection has improved certainty, definitely. But with up coming SMRs that are sealed for the life of the power plant, any fuel leak will render the entire project at risk.

FuseRing propose to use solid state induction to join away from the shoulder. The end product is tucked inside the tubing, away from circulating fluid and with two, maybe three barriers of security.

Details. Key is end cap geometry. By shaping end plug slightly smaller than ID of Zirc4 tubing but with thin fins protruding from body of the plug, similar to hair on forearm. Heat fins and plug using induction coil in an inert environment, Take to hot working temperature, plunge plug and fins into tubing thru coil winding. This will preseve as much heat as possible.

Simulation has show fins heat up slightly more than plug body. And by shaping the coils, heat is driven into plug body slightly w/out melting fins. As fins are plunged into tubing (because fins are slightly larger OD), fins will bend backwards. Plunge plug x mm into tubing and twist slightly.

Theory is to join tips of the fins to the ID of the tubing. Tubing walls are not heated. Objective is to transfer heat from fins to wall ID, solid state join tips of the fins to ID of the wall. Plug body will supply the remaining required heat to bond. Objective is to bond the tips of the fins and the first several atomic layers of wall ID. The rotation / shear is to break any large crystalls as it forms; by dynamic shear, just like conventional solid state, theory is fine grain will form between wall ID to fin tips.

There will need to be many experiments to find the optimum plug to fin geometry. But once proven that fin tips can join to wall ID, that will be one big step in quality improvement. Multiple fins can be shaped to secure isolation.

FuseRing and engineers are building Demo #2 using Zirc4 tubing 12 mm OD, wall 0.5 mm. Simulations complete, equipment are being designed. Expecting preliminary tubular welds Spring 2024.

Clamps to the tubing will need to be insulated so as not to act as a heat sink to the fins. Also first contact of fins to tubing will be a ceramic disk to help pre shapre the fins w/out un due stress on tubing shoulders.

Presenting Author: Paul Cheng Fusering Inc

Presenting Author Biography: Retired from Saudi Aramco 2016. Received 6 x USPTOs plus published and pending.

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