Radioactive Contamination Control Method in Neutron Source Damage Event in Tehran Research Reactor

The event of the initiator neutron source damage in the Tehran Research Reactor (TRR) caused to release a significant amount of radioactive materials in the primary cooling system of the TRR. The event caused the impuritie level to exceed beyound the allowed limit and to an extent that the present water purification system was not able to function effectively. Hence, elimination of radioactive pollutions was found to be a necessary task for the safe operation of the reactor. It was realized, initially that the contamination is due to very small particles size. Thus, the method of water treatment for the small-size particle elimination was found to be essential. For this purpose, the efficiency of fiber filters was studied for selecting the most efficient sample. In spite of implementation of a high particle removal efficiency, however, the effectiveness of the fiber filters in this process was found to be low, and consequently, it was concluded that contamination particles are ranged in a very small-size and in the dimensions of molecular size. Based on this investigation, the method of purification of molecular size impurities were examined. Our examinations showed that utilizing a carbon active filter is the best approach for purifiying the reactor primary cooling system. The laboratory results have also shown that the efficiency of carbon active filter of 40cm deeps is about 76% for removing the alpha emitter particles. By considering these results, we set up a filtration system for water purification with granular charcoal of 100cm deeps. After the successful purification of the polluted primary cooling system, the reactor was able to operate safely.