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Fred Henderson
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Why doesn't the ceramic pellets react with each other in the fuel tube when it is being fabricated?
A fresh does not need startup neutron sources to go critical or beyond critical. One can remove control elements (control rods in BWRs or PWRs) or dilute the boron in PWRs, and the core can attain keff > 1.montoyas7940 said:A new core with no fission products present might not (probably won't) fission at all. Start up sources (americium and californium IIRCC) are used to provide neutrons in a new core. Otherwise is would just sit there.
montoyas7940 said:Obviously we have never attempted a startup without sources or irradiated fuel.
For some utilities, a sourceless startup means not having to deal with hardware in the fuel. I know about start,up sources in PWR fuel, but I understand, there are not startup sources in BWR fuel, but they are in components somewhere in the core among fuel assemblies near the in-core instrumentation.anorlunda said:Does irradiated fuel make the source unnecessary? Never thought about that; probably yes. Still, the engineers need to be able to make a verifiable calculation. How much delta-k per second can the operator make, and how many seconds can elapse after criticality and before the onset of the reaction? They may prefer the known properties of a source to the uncalibrated decays of irradiated fuel.
montoyas7940 said:How does a fog nozzle overmoderate a fuel bundle? Wouldn't void coefficient be large? We store new fuel in liquid water at <100F and are far from criticality.
montoyas7940 said:A new core with no fission products present might not (probably won't) fission at all. Start up sources (americium and californium IIRCC) are used to provide neutrons in a new core. Otherwise is would just sit there.
Am I missing something?
anorlunda said:Does irradiated fuel make the source unnecessary? Never thought about that; probably yes. Still, the engineers need to be able to make a verifiable calculation. How much delta-k per second can the operator make, and how many seconds can elapse after criticality and before the onset of the reaction? They may prefer the known properties of a source to the uncalibrated decays of irradiated fuel.
QuantumPion said:Light water reactor fuel has two peaks in the moderator curve - one at typical cold water density and another at very low density similar to foam. Also note that new fuel is stored in water chock full of boron.
montoyas7940 said:Our reactor is a BWR and the water in the fuel storage pool is not borated -I am sure. I don't think the storage racks contain boron or halfnium but I will find out.
The double peak in the moderator curve is very interesting! Is it also true for BWR fuel? It would have to be wouldn't it since water is the moderator in both cases or is it due to the boron?
We use voids (similar to foam) to reduce reactivity.
Fuel tube thermal runaway is a phenomenon that occurs when the temperature of a fuel tube increases rapidly and uncontrollably, leading to a chain reaction that can cause fires or explosions.
Fuel tube thermal runaway can be caused by a variety of factors, such as a malfunction in the fuel tube's cooling system, a chemical reaction between the fuel and its container, or an external heat source.
To prevent fuel tube thermal runaway, proper safety measures must be in place, including regular maintenance of the fuel tube, proper handling and storage of the fuel, and monitoring of the temperature and pressure inside the fuel tube.
The potential dangers of fuel tube thermal runaway include explosions, fires, and release of toxic gases. These can cause serious harm to people, damage to property, and harm to the environment.
Fuel tube thermal runaway can be detected through various methods, such as temperature and pressure sensors, visual inspections, and thermal imaging. Regular monitoring and maintenance can also help in detecting any potential issues before they escalate.