shim rod

shim rod

[′shim ‚räd]
(nucleonics)
A control rod used for making occasional coarse adjustments in the reactivity of a nuclear reactor.
References in periodicals archive ?
SR: safety rod, ShR: shim rod, and AR: automatic regulating rod.
The effective multiplication factors, [k.sub.eff], were analyzed for two cases corresponding to the complete withdrawal and the full insertion of control rods (four shim rods and one automatic regulating rod).
The reactor core is controlled by seven control rods: two safety rods (SR), four shim rods (ShR), and one automatic regulating rod (AR).
Calculating the cross sections of the safety and shim rods is more complicated due to the strong absorption of the control rods.
In the case of full insertion of the four shim rods and the automatic regulating rod, the difference of the [k.sub.eff] values is about 242 pcm.
To do this, the four shim rods were inserted into the core.