On 20 August 1997 at 02:30 tests of the modified turbine controller were being carried out and for this reason three out of six main coolant pumps were switched off. Reloading of the reactor and the turbines occurred as expected. At 02:33 unexpedcted level increase in one of the six steam generators (SG) was observed. The level increase continued though the level interlock actuated properly and operator action was carried out. At 02:37 unit protection on high SG level actuated that caused the trip of both operating turbines and consequently reactor protection actuated. During the reactor protection actuation sticking of one of the 37 control rods was identified in a position about 200-250 cm (25-50 cm from the upper end position). The parameters of the reactor were stabilized. The cause of the SG level increase has not yet been identified. For defining the causes of the control rod sticking elaboration of a programme was started. Cooling down of the reactor was initiated. On 7 August 1997 sticking of the same control rod was identified during starting the reactor after annual outage. That time the sticking was eliminated with repeated operation of the rod. During additional tests of the affected rod the failure did not reoccur, the reactor was restarted. INES rating: Table II (chapter III-2.4.2) was used since initating event occurred (trip of both operating turbines). The frequency of the initiating event is expect (column 1 of the table). The reactor protection system is able to fulfill its safety function in case of sticking of one control rod, requirements set by the Technical Specifications were fulfilled. Therefore row B of the table was used and the basic rating 1/2 was selected. Additional uprating factor was taken into account according to chapter III-5.3. of the INES manual, namely the repetition of the event indicated that the possible lessons have not been learnt. The final rating was selected level 2.
Behnam Raeesian is an internationally recognized visual artist and poster designer from Iran, known for bold political and cultural works. Through exhibitions, workshops, jury roles, and collaborations with cultural institutions worldwide, he has built a strong voice in contemporary political graphic design. His projects confront complex issues such as nuclear risk and technological impact, transforming […]
Everywhere you look, the nuclear industry’s hype machine is in overdrive. Goldman Sachs, Microsoft, and the UK government all tout small modular reactors as the silver bullet for climate change and energy security. Tech billionaires are hiring nuclear veterans. Wall Street is whispering about “round-the-clock power” for artificial intelligence data centers. For those old enough […]
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A vast subsea nuclear graveyard planned to hold Britain’s burgeoning piles of radioactive waste is set to become the biggest, longest-lasting and most expensive infrastructure project ever undertaken in the UK. The project [UK's nuclear waste dump] is now predicted to take more than 150yrs to complete with lifetime costs of £66bn in today’s money...The […]
