Have pulsed fission reactors got any potential in nuclear energy?

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Discussion Overview

The discussion centers on the potential use of pulsed fission reactors in nuclear energy applications. Participants explore the feasibility, technical challenges, and operational characteristics of these reactors compared to conventional steady-state reactors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether pulsed fission reactors have any practical application in nuclear power, suggesting that the lack of need for pulsed operation might be a reason for their limited use.
  • Another participant requests clarification on whether the inquiry pertains to fission or fusion reactors, indicating a potential misunderstanding of reactor types.
  • A participant references an article stating that pulsed reactors are primarily used for research purposes, but the reasons for this limitation are not clearly explained.
  • Technical details are provided about the operation of pulsed reactors, including the typical pulse duration and the focus on transient behavior of nuclear fuel in response to hypothetical accidents.
  • Concerns are raised regarding the mechanical integrity of fuel during pulsed operation, including risks associated with pressure pulses and potential ruptures in the cooling system.
  • Discussion includes the observation that utilities do not operate power reactors in a pulsed mode, indicating a consensus on this operational limitation.
  • A mention of Project Orion is made, suggesting an alternative concept but dismissing its feasibility for use near Earth.

Areas of Agreement / Disagreement

Participants express a range of views on the practicality and safety of pulsed fission reactors, with some agreeing on their limited application primarily for research, while others raise technical concerns and operational limitations without reaching a consensus on their potential in power generation.

Contextual Notes

The discussion highlights various technical challenges associated with pulsed fission reactors, including issues related to delayed neutrons, fuel integrity, and operational safety, but does not resolve these complexities or provide definitive conclusions.

DyerMaker
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How did you find PF?: Searched for some forum about mechanical engineering in Google

Do pulsed nuclear fission reactors have any chances to be used in nuclear power?
If the answer is "no" is that just because of no need in pulsed operation mode while having a common one, are there any more complicated issues like ones with delayed neutrons or both these reasons?

Thank you!
 
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Thank you for you reply.
I am asking about pulsed fission reactors, like ones described here: https://www.euronuclear.org/glossary/pulsed-reactor/
It is claimed that's the only reasonable way to use them is to use them in research studies, but not explained why.
 
DyerMaker said:
Thank you for you reply.
I am asking about pulsed fission reactors, like ones described here: https://www.euronuclear.org/glossary/pulsed-reactor/
It is claimed that's the only reasonable way to use them is to use them in research studies, but not explained why.
Note in the Euronuclear article, it states "FRMZ, research reactor of the university of Mayence in Germany, type TRIGA-Mark-II; pulse power 250 MW, permanent power 0.1 MW." Pulses are typically in the 10's of ms (milli-seconds) for looking at 'transient behavior' of nuclear fuel, usually in response to a reactivity accident, which is a 'hypothetical' accident. The 'permanent' of 0.1 MW should be 'steady-state' power. After a pulse/test, the fuel is normally inspected to see if integrity is maintained.

Power reactors operate normally at constant power, although a reactor may 'load-follow'. Power maneuvering may be unrestricted, i.e., no restriction on power ascension (ramp) rates, but normally it's a few %/hr to 10-40%/hr, depending on the conditioning of the fuel. Often, if the fuel mechanical integrity is not limiting, the balance of plant (response of turbine/generator) is limiting. Another concern would be pressure pulses in the cooling system and potential for rupture of the piping or coolant boundary, as well as fatigue of the piping/pressure boundary.

There are technical limits on peak fuel enthalpy (stored energy) and temperature. With about 30% of fission products being isotopes of Xe and Kr (noble gases) with another significant fraction being Br, I, Rb, Cs, which are volatile well below the melting point of UO2/MOX fuel, the fuel could potentially balloon or rupture is the fuel temperature became too great, especially near the surface of the fuel.

Pulses in 'pulsed' reactor operation are completed well before the longer-lived delayed neutron precursors release neutrons, but on may observe their effect in the 'tail' after the pulse.

Utilities (power reactor operators) do not pulse their power reactors, nor would they plan to do so.
 
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Astronuc said:
Note in the Euronuclear article, it states "FRMZ, research reactor of the university of Mayence in Germany, type TRIGA-Mark-II; pulse power 250 MW, permanent power 0.1 MW." Pulses are typically in the 10's of ms (milli-seconds) for looking at 'transient behavior' of nuclear fuel, usually in response to a reactivity accident, which is a 'hypothetical' accident. The 'permanent' of 0.1 MW should be 'steady-state' power. After a pulse/test, the fuel is normally inspected to see if integrity is maintained.

Power reactors operate normally at constant power, although a reactor may 'load-follow'. Power maneuvering may be unrestricted, i.e., no restriction on power ascension (ramp) rates, but normally it's a few %/hr to 10-40%/hr, depending on the conditioning of the fuel. Often, if the fuel mechanical integrity is not limiting, the balance of plant (response of turbine/generator) is limiting. Another concern would be pressure pulses in the cooling system and potential for rupture of the piping or coolant boundary, as well as fatigue of the piping/pressure boundary.

There are technical limits on peak fuel enthalpy (stored energy) and temperature. With about 30% of fission products being isotopes of Xe and Kr (noble gases) with another significant fraction being Br, I, Rb, Cs, which are volatile well below the melting point of UO2/MOX fuel, the fuel could potentially balloon or rupture is the fuel temperature became too great, especially near the surface of the fuel.

Pulses in 'pulsed' reactor operation are completed well before the longer-lived delayed neutron precursors release neutrons, but on may observe their effect in the 'tail' after the pulse.

Utilities (power reactor operators) do not pulse their power reactors, nor would they plan to do so.
Thank you!
 
Well, there's always Project Orion, but we can forget about using it near Earth.
 

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