Plutonium is much rarer in nature than uranium and is more commonly used for bombs rather than as reactor fuel. Like uranium, it comes in various isotope forms, with plutonium 239 the most commonly used. It is mixed with the much more unstable plutonium 240 to generate power.
It's my understanding that a horse's knees close around age 2- 2 1/2. My gelding JUST turned 3. A couple days ago in fact. Will a horse's knees almost certainly be closed by that age?
By their late teens or early 20s, horses begin to show the signs of aging. Their backs begin to sag, and many develop age-related disorders such as kidney and liver disease. In the wild, these conditions contribute to rapid deterioration and death, but with proper care, horses can live into their mid 30s.