[en] NUPEC has started NUPEC Containment Integrity project entitled 'Proving Test on the Reliability for Reactor Containment Vessel' since June 1987. This is the project for the term of twelve years sponsored by MITI (Ministry of International Trade and Industry, Japanese Government). The test items are (1) Hydrogen mixing and distribution test, (2) Hydrogen Burning Test, (3) Iodine trapping characteristics test, and (4) Structural behavior test. Based on the test results, computer codes are verified and as the results of analysis and evaluation by the computer codes, containment integrity is to be confirmed. This paper indicates the results of hydrogen mixing and distribution test and hydrogen burning test. The NUPEC tests conducted so far suggest that hydrogen will be well mixed in the model containment vessel and the prediction by the computer code is in excellent agreement with the data. The NUPEC hydrogen burning test data is in good agreement with the FITS data at SNL that were obtained at the lower hydrogen concentration condition. (author)