Brazil
 INES 3 |
Potential Overexposure During Co-60 Source Exchange |
On July 21, 2008, two radiation workers, A and B, one American and one Brazilian, respectively, had received a potential overexposure. While in a hospital in the State of São Paulo, Brazil, they were in the process of exchanging an expended cobalt-60 source with a new cobalt-60 source. After engaging the source holder with the removal tool, worker A transferred the source holder from the unit head into the transfer cask. Once the source holder was in the transfer cask, worker A continued making preparations to complete the removal sequence.
INES 1 |
COOLANT RADIOACTIVITY EXCEEDING OPERATING LIMITS DUE TO FUEL ROD FAILURE |
Angra-1 had been experiencing some small fuel rods leakage since 4 months with primary water coolant activity indicating some percentage of Tech. Spec. limits. In 93.03.05 during a normal operation at 50% rated power a routine surveillance of reactor coolant activity detected values greater than the corresponding limiting conditions for operation. According to required actions the plant was immediately shut down following normal procedures. Preliminary estimations pointed out that around 100 fuel rods had failed. The utility is preparing defueling the core and inestigating the causes.
INES 2 |
TEMPORARY COMPLETE LOSS OF RESIDUAL HEAT REMOVAL |
During a scheduled outage for refueling and maintenance, the reactor, with the new fuel elements already in place, was in the cold shutdown condition. A loss of instrument air (due to loss of cooling of the non-safety related air compressors) led to full opening of a control valve of the residual heat removal (RHR) system, this led to an increase in the RHR pump flow. This pump was shut down by the operator, with the alleged intention of preventing its damage. The reactor stayed for 10 minutes without forced cooling and the reactor coolant temperature rose from 35 deg. C to 37 deg. C.
INES 0 |
LEAKOFF IN MOTOR BEARING HEAT EXCHANGER OF SERVICE WATER PUMP |
During normal operation of a leakoff in the motor bearing heat exchanger of service water pump was observed mixing coolant water with lubrificating oil of motor bearing. The pump was immediately shutoff and a backup pump was aligned for normal operational mode as requested by Technical Specifications.
INES 1 |
LEAKAGE IN THE GASEOUS WASTE PROCESSING SYSTEM (GWPS) |
During normal operation pressure decreases were observed in two (2) gas decay tanks of GWPS. The release time was approximately 4 hours and the estimated total radiation dose to the whole body of a critical individual was 10-4 mrem. The affected tanks were promptly isolated.
BASIS FOR RATING: As per INES Users' Manual page 10, "Failure of the barriers themselvesleading to radiological consequences will generally result inclassification by criteria 1 and 2 of the scale". As estimated dose waswell below the accepted limits the event was rated as level 1.
DIFFICULTIES IN RATING:
INES [N/A] |
FIRE IN GAS STORAGE |
During normal operation on the externally located gas storage facility, when a routine procedure was being done for change of a H2 cylinder, a fire was initiated and it was promptly extinguished.
BASIS FOR RATING: This event was considered as a typical industrial accident and notrelated to nuclear operations.
DIFFICULTIES IN RATING:
