The radioactive metals would not be in the core

The primary heavy radioactive metals are not chemically reactive with iron, but they are with oxygen. Therefore, most of them would form compounds that are not as heavy as the heavy metals in your definition.

Most of the heat you will get from the core would be from four metals (see this post on ES.SE for further details):

• Uranium 235, with a half-life of 0.703 billion years,
• Potassium 40, with a half-life of 1.277 billion years,
• Uranium 238, with a half-life of 4.468 billion years, and
• Thorium 232, with a half-life of 14.056 billion years.

These metals will form compounds that are no longer as dense as heavy metals, thus falling into the 'rock' category of Gimelist's answer to your last question.

A repeated melt cycle as proposed in your question will invfact increase the concentration of radioactive minerals in the crust and decrease them in the core. So relative to our Earth, your planet will have less radioactive heat in the core. Thus there will be less temperature differential across the mantle, and less convection.

What effects this has on geomagnetism and plate tectonics are hard to determine, but they don't sound good for life on the planet.