重铀酸铵（Ammonium diuranate）是化学物质的一种，浅黄色的固体，分子式为(NH₄)₂U₂O₇，是铀生产中的一种重要的中间产品。重铀酸铵具有放射性，它又有“黄饼”（Yellowcake）之称，以它的黄色外观得名。重铀酸铵加热至260℃时会分解成三氧化铀。

Ammonium diuranate or (ADU) ((NH₄)₂U₂O₇), is one of the radioactive intermediate chemical forms of uranium produced during yellowcake production. The name "yellowcake" originally given to this bright yellow substance, now applies to mixtures of uranium oxides which are actually hardly ever yellow. It also is an intermediate in mixed-oxide (MOX) fuel fabrication.