[en] A radioactively contaminated marine sediment core stemming from Irish Sea has been characterized by radiometric and mass spectrometric techniques as for ²³⁷Np, ²⁴¹Am, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu, ¹³⁷Cs and ¹⁵⁴Eu. The data obtained with independent methods in the framework of a QA/QC program as compared with the source term discharges, as well as with those reported in literature, are in good agreement. (author)