Search results
Results From The WOW.Com Content Network
Specific activity (symbol a) is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. [ 1 ] [ 2 ] It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g).
The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product. 226 Ra occurs in the decay chain of uranium-238 (238 U), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206.
Because of its relative longevity, 226 Ra is the most common isotope of the element, making up about one part per trillion of the Earth's crust; essentially all natural radium is 226 Ra. [29] Thus, radium is found in tiny quantities in the uranium ore uraninite and various other uranium minerals, and in even tinier quantities in thorium minerals.
It was originally defined as "the quantity or mass of radium emanation in equilibrium with one gram of radium (element)", [1] but is currently defined as 1 Ci = 3.7 × 10 10 decays per second [4] after more accurate measurements of the activity of 226 Ra (which has a specific activity of 3.66 × 10 10 Bq/g [5]).
Radium (88 Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is 226 Ra with a half-life of 1600 years. 226 Ra occurs in the decay chain of 238 U (often referred to as the radium series). Radium has 34 known isotopes from 201 Ra to 234 Ra.
The official United States Government Manual offers no definition. [ 1 ] [ 2 ] While the Administrative Procedure Act definition of "agency" applies to most executive branch agencies, Congress may define an agency however it chooses in enabling legislation, and through subsequent litigation often involving the Freedom of Information Act and the ...
The National Credit Union Administration (NCUA), government backer of credit unions, equivalent to the FDIC. The National Labor Relations Board (NLRB) administers the principal United States labor law, the National Labor Relations Act. The board is vested with the power to prevent or remedy unfair labor practices and to safeguard employees ...
The Department of Defense Activity Address Code (DoDAAC) is a six position code that uniquely identifies a Department of Defense unit, activity, or organization that has the authority to requisition, contract for, receive, have custody of, issue, or ship DoD assets, or fund/pay bills for materials and/or services. The first positions of the ...