Does neutron embrittlement pose a real threat in this century?

[BenKlesc]

I've been reading up on neutron embrittlement lately. However I go onto the DOE's website, and they are now saying that there really is no technical limit to how long a reactor can stay operational.

Eventually I believe in the next 100 years because of embrittlement, reactors will have to be shut down and rebuilt. Does this mean we are going to have to build 100 reactors in this century to keep up?

 

[Astronuc]

I've been reading up on neutron embrittlement lately. However I go onto the DOE's website, and they are now saying that there really is no technical limit to how long a reactor can stay operational.

Eventually I believe in the next 100 years because of embrittlement, reactors will have to be shut down and rebuilt. Does this mean we are going to have to build 100 reactors in this century to keep up?

The original commercial reactors were designed for 40 years and 20% margin to capacity. In the past two decades, as some plants approached 40 years, we've evaluated the materials and determined that reactor vessels can operate to 60 years. Now as some plants pass 40 years, we are looking beyond 60 years to 80 years.

Back in the 1960s and 1970s, we did not have 40 years experience. Some of the oldest plants were shutdown and decommissioned well before their full life, since they were essentially uneconomical compared to alternatives, e.g., gas-fired generation. From those that have operated 40+ years, we are still learning about the effects of radiation (dose (dpa) accumulation) and operation at temperature (thermal aging). There have been some efforts at annealing the pressure vessels, if that is necessary.

The pressure vessels operate with some distance from the core, but they still receive some neutron and gamma irradiation, which varies azimuthally around the core. Core internals made of stainless steel receive more irradiation, but they can be replaced, up to a point.

I'll see if I can find some references.

 

[gmax137]

The good news is, this was considered in the original plant design: material coupons of the steel used in the vessel forgings were placed in holders inside the vessel. So now, every ten years or so a coupon can be retrieved and studied and the actual effects of the actual neutron fluence on the actual steel used in that vessel can be determined.

 

[Astronuc]

DOE's Light Water Reactor Sustainability (LWRS) program hosted at INL the repository for reports on the work being done regarding reactor pressure vessel (RPV) aging and aging of various other components and materials.

https://lwrs.inl.gov/Materials Aging and Degradation/Forms/AllItems.aspx

https://lwrs.inl.gov/Materials Aging and Degradation/LWRS NDE RD Roadmap_9-12-2012.pdf

Relevant to the OP:
https://lwrs.inl.gov/Materials Agin...teel_under_light_water_reactor_conditions.pdf (Despite the title, the report includes some discussion of ferritic alloys used in RPV.

RPV steels include SA508 Cl 2a, SA533 Gr A Cl 2, SA508 Cl 3a and SA533 Gr B Cl 2.

 

[BenKlesc]

DOE's Light Water Reactor Sustainability (LWRS) program hosted at INL the repository for reports on the work being done regarding reactor pressure vessel (RPV) aging and aging of various other components and materials.

https://lwrs.inl.gov/Materials Aging and Degradation/Forms/AllItems.aspx

https://lwrs.inl.gov/Materials Aging and Degradation/LWRS NDE RD Roadmap_9-12-2012.pdf

Relevant to the OP:
https://lwrs.inl.gov/Materials Aging and Degradation/Thermodynamic_and_kinetic_model_of_phase_stability_in_austenitic_steel_under_light_water_reactor_conditions.pdf (Despite the title, the report includes some discussion of ferritic alloys used in RPV.

RPV steels include SA508 Cl 2a, SA533 Gr A Cl 2, SA508 Cl 3a and SA533 Gr B Cl 2.

Thanks! As someone who is just entering the industry out of school, I really do worry if we will have the capability or means to replace most of the reactors in the United States that are now nearing 50 years of age. Eventually they will need to be rebuilt, but the question remains will they be rebuilt.

That's also very true! I was reading up on Yankee Rowe and how it was shut down prematurely. It was the first nuclear plant in the country to ask for an extension to their license, and the Union Of Concerned Scientists petitioned the NRC to shut it down because they were concerned about embrittlement. It was shut down, but now we know this is happening to every reactor.

That's also good to hear that we have the coupons, so we can know it's not at risk of melting down while it's operating. We can monitor it closely. That used to be one of the more greater concerns and argument against the technology as they age.

 

[artis]

I think it is not a technical matter or problem to rebuild an expired power plant but rather an economical and political problem.

Economy wise if something else which is also environmentally acceptable will get much cheaper investors usually go that way as a nuke plant is rather expensive and due to countless regulations and political pressure also a risky business.
Eventually I think maybe not all but some plants will get new ones built in their place because our energy needs don't seem to decrease rather the opposite.