Modeling of postulated accident release of 99MoO3 powder from ETRR-2 Stack

The postulated accident modeled in this study simulates the release of 99MoO3 powder, activated by neutrons, to the environment through the ventilation system of the universal cell of ETRR-2 (Egyptian second nuclear research reactor). The simulation was carried out in both the normal and abnormal situation cases. The 98MoO3 powder was contained in an ampoule of quartz surrounded with a tight Aluminum can. The can is purposed to be irradiated in the ETRR-2 irradiation grid with a neutron flux of 1.4 × 1014 n/cm2 s to produce 99MoO3. The Aluminum can was delivered after irradiation to the universal cell to remove the quartz ampoule to the outside the Aluminum can. During the process of removing the quartz ampoule from the Aluminum can, the ampoule may be broken due to a human error and the 99MoO3 powder released in the universal cell that is connected to the hot cell ventilation system. The postulated radiation doses to the public at various downwind distances were calculated using the health physics computer code HotSpot 2.06 developed at the Lawrence Livermore National Laboratory, USA. This study is a complementary study for 99MoO3 production safety document. The results indicated that the persons who are within downwind distances for all metrological conditions (A-F classes) would receive a committed effective dose (CED) less than the permissible dose for both the normal and abnormal cases.