Mexico
 INES 0 |
Hydrogen Recombiner functional testing not satisfactory |
On January 24, 2011 the Laguna Verde NPP Unit 2 was operating at 21% of rated power. While testing the Hydrogen Recombiner System Division I, it was observed that there was not an increment in the temperature of its heater; therefore the test was not satisfactory. All other safety systems were at operative condition.
INES 2 |
Reactor trip due to high pressure in the reactor pressure vessel |
On January 19, 2011 the Laguna Verde NPP Unit 2 was operating at 43.2% of rated power in process for testing. According to the sequence of events, it follows that: While testing for the load rejection signal, the main turbine incremented its speed. The main turbine control valves started to close while controlling the turbine speed. The pressure at the first step in the turbine was at 17 kg/cm2, with the control valves closed. Then, the pressure at the first step started to decrease until 4.6 kg/cm2.
INES 0 |
Reactor trip due to failure in the Main Generator |
On January 15, 2011, Laguna Verde NPP Unit 1 was operating at 37.3 % rated power and in the process of decreasing power in order to repair a component related to the electrical protection of the main generator. Suddenly there was an automatic reactor trip due to the failure of this electrical protection. All safety systems were in operative condition and worked as required, and the reactor was taken to a safe shutdown condition.
INES 1 |
Potential damage in riser pipe at Laguna Verde NPP U2 |
On October 22, 2010, Laguna Verde NPP Unit 2 personnel found during the outage inspection that the riser pipe of two jet pumps of the recirculation system were affected with a small crack. The root cause of this event is still in investigation. Corrective actions are still in planning and the refueling activities are in hold.
INES 1 |
Non Usual Event declared due to loss of outside power at Laguna Verde NPP U1 |
On December 02, 2010, Laguna Verde NPP Unit 1 was operating at 87.5 % rated power, when a loss of outside power event ocurred, and a Non Usual Event was declared by the operator. All safety systems worked as required, including all three diesel generators; and the reactor was taken to a safe shutdown condition.
INES 2 |
Engineering Safety Feature Inoperative at Laguna Verde NPP-1 |
On July 12, 2002 while the reactor was increasing power following inspection and repairing of small leaks in the main steam tunnel, there was an automatic shutdown. The cause was human failure of the main control personnel to control reactor pressure. During recovery actions, it was found that the Reactor Core Isolation Cooling system (RCIC) was inoperative.
INES 2 |
Internal contamination of workers in a Medical Center |
On November 28, 2002 a technician of the Nuclear Medicine Department of the Medical Center “Centro Médico Siglo XXI” reported to the National Commission on Nuclear Safety and Safeguards - CNSNS (Mexico’s nuclear regulatory body) that he and eight of his co-workers were contaminated with I-131. The technician became aware of the problem because radiation alarms activated while his co-workers were around. The nine workers were checked with a whole body counter at the regulatory body’s laboratory, and the results verified the internal contamination of the workers.
INES 2 |
Fuel assembly drop during refuelling |
On November 21, 1998 while performing refuelling, at the time of unloading the core and lifting a spent fuel assembly, a failure occurred affecting the refuelling machine which caused the spent fuel assembly to slump to the reactor core. The fuel assembly was taken to a safe condition. Reactor vessel water and refuelling floor atmosphere were monitored without finding any abnormal changes.
INES 1 |
A NON USUAL EVENT DUE TO THE LIBERATION OF GASES INSIDE THE PLANT |
A non usual event was declared due to the detection of domestic gas odor. The cause of the event was the activation of the relief valve of the stationary tank of gas placed at the roof of the control building. The gas was suctioned by the HVAC system. This event took place during the task to fill the tank.
INES 1 |
RECIRCULATION TRANSIENT WITH A SUDDEN INCREASE IN POWER OVER 100% |
Valve RRC-FCV-8830B opens, the HPU-B subloop 2 trips and subloop 1 does not start in its auto mode producing a peak in the neutronic flux: APRM A 108%, APRM C 109%, APRM D 115% and the flow through the core is 29.4 KT/hr. Power can be lowered with the recirculation loop A: loop "A" 1550 LPS; Loop "B" 1890 LPS and power is at 1915 MWT.
Initiator event: recirculation transient with a sudden increase in power frequency: expected.
