The 2021 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments contains data from 169 experimental series that were performed at 57 nuclear facilities. A total of 165 of the 169 evaluations are published as approved benchmarks. The remaining four evaluations are published as draft documents only.

The cover of the handbook shows the ZPR-9 machine at Argonne National Laboratory-East in Illinois to support development of a gas cooled fast reactor (GCFR), in the United States.

Newly evaluated criticality, control worth, and spectral characteristics measurements from ZPR-9 have been added to this edition of the handbook.

The information and data included in this handbook are available to NEA member countries, to all contributing countries and to others on a case-by-case basis.

Example calculations are presented; however, these do not constitute validation or endorsement of the codes or cross-section data.