Supercritical water cooled reactor during LBLOCA

In summary, during a LB LOCA in a SCWR, there would be a rapid depressurization that would initially decrease reactivity. However, as the water changes to a two-phase flow, the void effect would cause reactivity to increase again. There are specialized software and resources available for simulating SCWRs, and reaching out to experts in the field may also provide helpful information.
  • #1
Jock Flannigan
2
0
Hello,

I was wondering, how would SCWR react during LB LOCA, mainly at the time of a break. There is fast depressurization of cource, but what will happen to reactivity in first few seconds after the break? I would expect to get a two-phase flow fairly soon and then it should be like a normal BWR.

The problem is, there not many tools that can simulate it (TRACE and RELAP do not have SC correlations and only ATHLET has Mokry correlation, which is not very precise).

Or if anyone has any good online materials on SCW, I would really appreciate it (old lectures from Unis etc).

Thanks!
 
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  • #2
Ostensibly, a SCWR is designed to scram on a depressurization signal. To simulate a LBLOCA, one would need a system code like RELAP or VIPRE/RETRAN with the appropriate properties. I would image someone has done that. The question then is, has someone published such study? Perhaps in the Gen4 forum.

Meanwhile here are some properties - Thermophysical Properties at Critical and Supercritical Conditions
http://cdn.intechweb.org/pdfs/13204.pdf

http://www1.lsbu.ac.uk/water/supercritical_water.html

There is a paper "Safety analysis code SCTRAN development for SCWR and its application to CGNPC SCWR" in Annals of Nuclear Energy, but it requires purchase.
http://www.sciencedirect.com/science/article/pii/S0306454913000455

http://www.osti.gov/scitech/biblio/22107829
 
  • #3


Hi there,

That's a great question! From my understanding, during a LB LOCA (large break loss of coolant accident), the SCWR (supercritical water reactor) would experience a rapid depressurization as you mentioned. This would cause a decrease in reactivity due to the decrease in pressure. However, as the water changes to a two-phase flow, the reactivity would start to increase again due to the void effect. The void effect refers to the decrease in moderation of neutrons as the water changes from liquid to vapor, which leads to an increase in reactivity.

As for simulation tools, I'm not too familiar with the specific ones you mentioned, but I would suggest looking into more specialized software that is specifically designed for SCWR simulations. You could also try reaching out to experts or researchers in the field for more information and resources.

I hope this helps! Good luck with your research.
 

Related to Supercritical water cooled reactor during LBLOCA

1. What is a Supercritical Water Cooled Reactor (SCWR)?

A SCWR is a type of nuclear reactor that uses supercritical water as its coolant. This means that the water is heated to a temperature and pressure above its critical point, where it exists as a single phase, rather than as separate liquid and gas phases.

2. What is LBLOCA?

LBLOCA stands for Large-Break Loss-of-Coolant Accident. It refers to a scenario in which a break in the reactor coolant system causes the loss of a large amount of coolant, leading to a rapid decrease in reactor core cooling capacity.

3. How does a SCWR handle LBLOCA events?

A SCWR is designed to withstand LBLOCA events by utilizing passive safety features. These features include a large inventory of water in the reactor, passive cooling systems, and a negative void reactivity coefficient, which means that the reactor becomes less reactive as the coolant expands during a loss-of-coolant accident.

4. What are the main challenges in using supercritical water as a coolant in a nuclear reactor?

One of the main challenges is the high temperature and pressure conditions required for the water to remain in its supercritical state. This places significant demands on the materials used in the reactor, as they must be able to withstand these extreme conditions while also maintaining their structural integrity.

5. What are the potential benefits of using a SCWR during LBLOCA events?

The use of a SCWR can potentially improve the safety and efficiency of nuclear power plants. The passive safety features of a SCWR can help prevent or mitigate the consequences of a LBLOCA event. Additionally, the high temperature and pressure conditions of supercritical water can increase the thermal efficiency of the reactor, leading to a more efficient use of nuclear fuel.

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