Block from U+2E80 to U+2EFF. This block was introduced in Unicode version 3.0 (1999). It contains 115 codepoints.
The Wikipedia provides the following information on block CJK Radicals Supplement:
CJK Radicals Supplement is a Unicode block containing alternative, often positional, forms of the Kangxi radicals. They are used headers in dictionary indices and other CJK ideograph collections organized by radical-stroke.