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?
Typically the onset of osteoarthritis (OA) in adult horses is 4 to 6 years old, but that can vary a great deal due to breed of the horse and its use. Conformation is also a very important consideration leading to OA.