TINH TOAN LIEU CHIEU TRONG MQT S TRUOfNG HgfP SV CO NGHIEM TRQNG CUA THIET BI CHIEU XA SVST-C06O/B TRAN KHAC AN, CAO VAN CHUNG, TRAN VAN HtlNG, NGUYEN ANH TUAN Trung tdm Nghien ctru vd Trien khai Cdng ngh? Biic xg Abstract: Two serious accidents which could happen to SVST-C06O/B irradiator are assumed: the source racks are jammed and could not return to the storage position and a source pencil is knocked out on the production maze by a tote-box By using MCNP code the calculation of exposure doses in the approach zone and the residential area outside the facility for two above-mentioned cases has been carried out and its results for both cases show that the exposure doses in the approach zone are higher than the limit dose (>100 mSv/h) but the exposure doses in the residential area are still in safe range (