plutonium core later nicknamed "demon core"
E192861
The plutonium core later nicknamed the "demon core" was a subcritical mass of plutonium used in Manhattan Project criticality experiments that caused two fatal radiation accidents, including the one that killed physicist Louis Slotin.
All labels observed (1)
| Label | Occurrences |
|---|---|
| plutonium core later nicknamed "demon core" canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T1717458 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: plutonium core later nicknamed "demon core" Context triple: [Louis Slotin, experimentedOn, plutonium core later nicknamed "demon core"]
-
A.
K-West Reactor
K-West Reactor is one of the plutonium production reactors at the Hanford Site in Washington State, historically used to support the U.S. nuclear weapons program.
-
B.
X-10 graphite reactor
The X-10 graphite reactor was an early nuclear reactor at Oak Ridge, Tennessee, built during the Manhattan Project as a pilot plant for plutonium production and a key step toward the development of nuclear weapons and nuclear energy.
-
C.
K-25 Project
The K-25 Project was a World War II–era Manhattan Project effort to build and operate a massive gaseous diffusion plant for uranium enrichment in Oak Ridge, Tennessee.
-
D.
Chicago Pile-2
Chicago Pile-2 was an early research nuclear reactor built at the Argonne site to continue and expand experimental work following the first controlled chain reaction achieved by Chicago Pile-1.
-
E.
D Reactor
D Reactor was one of the early plutonium production reactors at the Hanford Site in Washington, built during the Manhattan Project to support the U.S. nuclear weapons program.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: plutonium core later nicknamed "demon core" Target entity description: The plutonium core later nicknamed the "demon core" was a subcritical mass of plutonium used in Manhattan Project criticality experiments that caused two fatal radiation accidents, including the one that killed physicist Louis Slotin.
-
A.
K-West Reactor
K-West Reactor is one of the plutonium production reactors at the Hanford Site in Washington State, historically used to support the U.S. nuclear weapons program.
-
B.
X-10 graphite reactor
The X-10 graphite reactor was an early nuclear reactor at Oak Ridge, Tennessee, built during the Manhattan Project as a pilot plant for plutonium production and a key step toward the development of nuclear weapons and nuclear energy.
-
C.
K-25 Project
The K-25 Project was a World War II–era Manhattan Project effort to build and operate a massive gaseous diffusion plant for uranium enrichment in Oak Ridge, Tennessee.
-
D.
Chicago Pile-2
Chicago Pile-2 was an early research nuclear reactor built at the Argonne site to continue and expand experimental work following the first controlled chain reaction achieved by Chicago Pile-1.
-
E.
D Reactor
D Reactor was one of the early plutonium production reactors at the Hanford Site in Washington, built during the Manhattan Project to support the U.S. nuclear weapons program.
- F. None of above. chosen
Statements (37)
| Predicate | Object |
|---|---|
| instanceOf |
Manhattan Project artifact
ⓘ
nuclear experiment device ⓘ plutonium core ⓘ |
| associatedWithCountry |
United States of America
ⓘ
surface form:
United States
|
| associatedWithInstitution |
Los Alamos Laboratory
ⓘ
surface form:
Los Alamos National Laboratory
|
| associatedWithPhysicist |
Harry Daghlian
ⓘ
Louis Slotin ⓘ |
| associatedWithProgram | U.S. nuclear weapons development ⓘ |
| associatedWithRisk | prompt criticality ⓘ |
| causedAccident |
Harry Daghlian criticality accident
ⓘ
Louis Slotin ⓘ
surface form:
Louis Slotin criticality accident
|
| causedDeathOf |
Harry Daghlian
ⓘ
Louis Slotin ⓘ |
| era | World War II ⓘ |
| experimentType | hand-assembled criticality experiments ⓘ |
| firstAccidentDate | 1945-08-21 ⓘ |
| firstAccidentType | criticality accident ⓘ |
| hasAlternativeName |
demon core
ⓘ
plutonium core later nicknamed "demon core" ⓘ |
| historicalSignificance | notorious example of laboratory criticality hazard ⓘ |
| intendedTargetContext | planned third atomic bomb in World War II ⓘ |
| intendedUse | core for a third nuclear weapon ⓘ |
| isSubcriticalMass | true ⓘ |
| locationDuringUse | Los Alamos Laboratory ⓘ |
| material | plutonium ⓘ |
| nicknameOrigin | given after fatal criticality accidents ⓘ |
| notUsedInCombat | true ⓘ |
| numberOfFatalAccidents | 2 ⓘ |
| postAccidentDisposition | eventually melted down and recycled into other cores ⓘ |
| radiationExposureConsequence | acute radiation syndrome ⓘ |
| safetyLesson | led to stricter criticality safety procedures ⓘ |
| secondAccidentDate | 1946-05-21 ⓘ |
| secondAccidentType | criticality accident ⓘ |
| usedFor | criticality experiments ⓘ |
| usedInProject | Manhattan Project ⓘ |
| yearOfFirstAccident | 1945 ⓘ |
| yearOfSecondAccident | 1946 ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: plutonium core later nicknamed "demon core" Description of subject: The plutonium core later nicknamed the "demon core" was a subcritical mass of plutonium used in Manhattan Project criticality experiments that caused two fatal radiation accidents, including the one that killed physicist Louis Slotin.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.