Neutron Embrittlement of Pressure Vessels

In summary: IN SUMMARY], The radiation emitted from a nuclear reactor is composed of gamma rays and neutrons. Neutrons are a byproduct of the nuclear reactions that power the reactor, but they are lost in the energy production process. This “neutron leakage” represents a loss of fuel efficiency and causes neutron embrittlement of the reactor pressure vessel (RPV) wall. The latter raises safety concerns, needs to be monitored closely and may necessitate mitigating measures. There are different strategies to deal with these two undesirable effects: reducing the emission of neutrons all around the core, just at the “hot spots” of RPV embrittlement, or using a larger water gap between the core and the
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Neutron fluence at the reactor pressure vessel wall a comparison of French and German procedures and strategies in PWRs

U. Jendrich (GRS), N. Tricot (IRSN)

Abstract: While the neutrons within the core may take part in the chain reaction, those neutrons emitted from the core are basically lost for the energy production. This “neutron leakage” represents a loss of fuel efficiency and causes neutron embrittlement of the reactor pressure vessel (RPV) wall. The latter raises safety concerns, needs to be monitored closely and may necessitate mitigating measures. There are different strategies to deal with these two undesirable effects: The neutron emission may be reduced to some extent all around the core or just at the “hot spots” of RPV embrittlement by tailored core loading patterns. A higher absorption rate of neutrons may also be achieved by a larger water gap between the core and the RPV. In this paper the inter-relations between the distribution of neutron flux, core geometry, core loading strategy, RPV embrittlement and its surveillance are discussed at first. Then the different strategies followed by the German and French operators are described. Finally the conclusions will highlight the communalities and differences between these strategies as different approaches to the same problem of safety as well as economy.

www.eurosafe-forum.org/ipsn/pdf/euro2_1_1neutron_fluence.pdf [/URL]

GRS - Gesellschaft für Anlagen- und Reaktorsicherheit mbH - is a scientific-technical expert and research organisation. - [PLAIN]http://www.grs.de/en/index.html [Broken]

IRSN - Institut de Radioprotection et de Sureté Nucléaire - http://www.irsn.fr/ (click on English Version to the right)
 
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Both neutron reflection as well as gamma ray reflection need to be looked into. The problem is that neutrons are a byproduct in current thermal-fission reactors, but in the future when more truley aneutronic fusion reactors are develped, the thermal neutron problem will be less severe. However, gamma rays are a large problem because every reaction, both fission and fusion unleash a few MEV of gamma rays. So for each nuclear reaction, gamma expels from the nucleus, and this builds up problems of tremendous heat and irradiation. These cause biohazardous radiation problems as well as heating the walls. Although gamma rays are a high frequency of electromagnetic rays on the EM spectrum than that of visible light, we should still look into reflecting them back into the system or using some form of photovoltaic energy production. Though most likely the rays will penetrate any normal matter, both heating and irradiating it...
 
  • #3
Thank you for sharing this interesting paper on neutron fluence in PWRs. It is important to consider the impact of neutron leakage on fuel efficiency and the safety of the reactor pressure vessel wall.

I found it particularly interesting that there are different strategies to address these issues, such as reducing neutron emission or increasing neutron absorption. It is also worth noting the differences between the approaches taken by German and French operators.

I appreciate the links to GRS and IRSN, which provide more information on these organizations and their work in this field. It is reassuring to know that there are scientific-technical experts and research organizations dedicated to ensuring the safety and efficiency of nuclear reactors.

Thank you for sharing this informative paper and providing valuable resources for further reading.
 
  • #4
Thank you for sharing this interesting paper on neutron fluence in PWRs. It is important to consider the impact of neutron leakage on fuel efficiency and the safety of the reactor pressure vessel wall.

I found it particularly interesting that there are different strategies to address these issues, such as reducing neutron emission or increasing neutron absorption. It is also worth noting the differences between the approaches taken by German and French operators.

I appreciate the links to GRS and IRSN, which provide more information on these organizations and their work in this field. It is reassuring to know that there are scientific-technical experts and research organizations dedicated to ensuring the safety and efficiency of nuclear reactors.

Thank you for sharing this informative paper and providing valuable resources for further reading.
 

What is neutron embrittlement?

Neutron embrittlement is a phenomenon where the mechanical properties of a material, such as its strength and ductility, are degraded due to exposure to high levels of neutron radiation.

What causes neutron embrittlement in pressure vessels?

Neutron embrittlement in pressure vessels is primarily caused by the absorption of neutrons by the metal atoms in the vessel's structure. This leads to the formation of defects and changes in the microstructure of the material, which can weaken its mechanical properties.

How does neutron embrittlement affect the safety of pressure vessels?

Neutron embrittlement can cause pressure vessels to become brittle and more susceptible to cracking or failure. This can compromise the safety of the vessel and potentially lead to catastrophic accidents.

What types of materials are most susceptible to neutron embrittlement?

Materials with high levels of alloying elements, such as steel and nickel-based alloys, are most susceptible to neutron embrittlement. These materials are commonly used in the construction of pressure vessels.

How can neutron embrittlement be prevented or mitigated?

To prevent or mitigate neutron embrittlement, materials with low neutron absorption rates can be used in the construction of pressure vessels. Additionally, regular monitoring and inspection of the vessel's condition can help identify any potential issues before they become a safety concern.

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