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?
Stabled animals tend to appear younger than they are, whereas those grazing sandy areas, such as range horses, appear relatively old because of wear on the teeth. Horses, like people, vary considerably in vigor and longevity. In general, they have passed their physical peak when they reach 9 to 10 years of age. At this age, the chance of an unsoundness being present has increased. Age determination is made by a study of the 12 front teeth, called incisors.