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The displacement of water in the lower 1.25 m of the core as the rod moves down could cause a local increase of reactivity in the bottom of the core as the graphite part of the control rod passes that section. This "positive scram" effect was discovered in 1983 at the Ignalina Nuclear Power Plant. The control rod channels are cooled by an ...
Following a scram, if the reactor (or section(s) thereof) are not below the shutdown margin (that is, they could return to a critical state due to insertion of positive reactivity from cooling, poison decay, or other uncontrolled conditions), the operators can inject solutions containing neutron poisons directly into the reactor coolant.
The RBMK reactors also have a flawed control rods design in which during rapid scrams, the graphite reaction enhancement tips of the rods would displace water at the bottom of the reactor and locally increase reactivity there. This is called the "positive scram effect" that is unique to the flawed RBMK control rods design.
The study, published in Environmental Health Perspectives, examined the effects of PM2.5, a mixture of microscopic particles measuring less than 2.5 micrometers in diameter. These particles can ...
At Chernobyl in 1986, a poorly understood positive scram effect resulted in an overheated reactor core. This led to the rupturing of the fuel elements and water pipes, vaporization of water, a steam explosion, and a graphite fire. Estimated power levels prior to the incident suggest that it operated in excess of 30 GW, ten times its 3 GW ...
President-elect Donald Trump has said he might install his picks for top administration posts without first winning approval in the U.S. Senate. This would erode the power of Congress and remove a ...
Canadian Prime Minister Justin Trudeau returned home Saturday after his meeting with Donald Trump without assurances the president-elect will back away from threatened tariffs on all products from ...
The primary design cause of the accident, as determined by INSAG-7, was a major deficiency in safety features, [2]: 22 particularly the "positive scram" effect that was caused by the control rods' graphite tips that initially increased reactivity when control rods entered the core to try to reduce reactivity.