Uranium shells

Uranium shells were projectiles made from depleted uranium and an upgraded version of the standard shells used by PLA tanks. They were available to Chinese commanders at the nuclear missile silo.

Background
China's reliance upon nuclear energy left them with a growing supply of depleted uranium. Their solution to this build-up was to use the extremely dense element in their tank shells. Compared to more conventional tank shells, depleted uranium shells had more penetrating power and were overall more effective in combat.

In order to gain access to depleted uranium shells, the uranium shells upgrade needed to be researched from the nuclear missile silo. The upgrade made all Battlemaster and Overlord tanks deal 25% more damage with their main guns.

True to his infamous fondness for all things nuclear, General Tsing Shi Tao's tanks already came armed with depleted uranium shells without having to purchase the upgrade. In addition, his tanks used uranium shells which also emitted residual radiation, increasing their effectiveness against infantry.

General Shin Fai could not gain this upgrade on his own, although he did not have much use for it considering that tanks were not used in his doctrine.

Trivia
Tao was supposed to be able to upgrade his tanks even further with the removed weapons grade uranium shells upgrade. You can use this upgrade in some mods, such as Shockwave.
 * Depleted uranium ammunition is commonly used in tank guns and artillery cannons. Despite having much of its radioactivity used, DU munitions remain harmful and can still leave effects upon the human body.