neutron poison
C2Technical / Scientific / Nuclear Engineering
Definition
Meaning
A substance that absorbs neutrons in a nuclear reactor without undergoing fission, slowing or stopping the chain reaction.
In a broader sense, any material or element with a high neutron absorption cross-section that interferes with the efficiency of a nuclear reaction. It can also be used metaphorically for something that impedes progress or efficiency in a system.
Linguistics
Semantic Notes
The term is not a toxin or chemical poison; the 'poison' is metaphorical, indicating an agent that 'kills' or 'absorbs' neutrons, harming the chain reaction. It is a count noun (e.g., 'Xenon is a neutron poison').
Dialectal Variation
British vs American Usage
Differences
No significant lexical or orthographic differences. The concept is identical in both varieties, used exclusively in technical contexts.
Connotations
Identical technical connotations. Potential metaphorical use is extremely rare in both.
Frequency
Extremely low frequency in general language, confined to specialised nuclear physics and engineering texts in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
[Substance] is/acts as a neutron poison.The accumulation of [neutron poison] reduces reactivity.Engineers must compensate for the [neutron poison].Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[No established idioms for this highly technical term]”
Usage
Context Usage
Business
[Not used]
Academic
Used in nuclear physics, engineering, and energy studies journals and textbooks.
Everyday
[Virtually never used]
Technical
Core term in nuclear reactor design, operation, and safety analysis.
Examples
By Part of Speech
verb
British English
- [No standard verb form. The process is 'to poison (the reaction with a neutron absorber)'.]
American English
- [No standard verb form. The process is 'to poison (the core with xenon)'.]
adverb
British English
- [No standard adverb form]
American English
- [No standard adverb form]
adjective
British English
- The xenon-135 isotope has significant neutron-poisoning properties.
- They calculated the neutron-poison effect.
American English
- The build-up created a neutron-poisoning scenario.
- Boron has a high neutron-poison cross-section.
Examples
By CEFR Level
- [This term is far above A2 level.]
- [This term is far above B1 level.]
- Nuclear reactors use control rods to manage neutron poisons.
- Some materials produced in a reactor can become neutron poisons.
- The transient fission product xenon-135 is a potent neutron poison that complicates reactor restart after a shutdown.
- Reactor operators must carefully model the build-up and burn-up of various neutron poisons to maintain criticality.
Learning
Memory Aids
Mnemonic
Imagine a 'poison' for a neutron's 'life'—instead of making it split atoms (fission), the poison absorbs and 'kills' it, stopping the reaction chain.
Conceptual Metaphor
POISON IS AN UNWANTED ABSORBER (Metaphor from biology/chemistry applied to physics: a substance that 'kills' the necessary particles for a process).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating 'poison' literally as 'яд' in a chemical hazard sense. The Russian technical equivalent is 'нейтронный поглотитель' or 'нейтронный яд' (the latter is a direct calque).
- The term describes a functional role, not a hazardous chemical property to humans directly.
Common Mistakes
- Using it as a mass noun (e.g., 'too much neutron poison'). Better: 'too high a concentration of neutron poison'.
- Confusing it with 'radioactive poison' or 'toxic waste'. A neutron poison is defined by its nuclear property, not its chemical toxicity.
Practice
Quiz
What is the primary characteristic of a neutron poison?
FAQ
Frequently Asked Questions
No. The term 'poison' is a metaphor from reactor physics. It refers to the material's ability to 'kill' the chain reaction by absorbing neutrons. The material itself may or may not be chemically toxic.
Xenon-135 is a classic example, as it is a fission product with an extremely high neutron absorption cross-section. Boron-10, often used in control rods, is another intentional neutron poison.
Yes. Materials used as neutron poisons (like boron in control rods or gadolinium as a burnable absorber) are essential for controlling and shutting down nuclear reactors safely.
Some, like xenon-135, 'burn out' by absorbing a neutron and transforming into a different, less absorptive isotope. Others are physically removed or diluted through fuel management and reactor operation.