Hazards Summary Report for the VMR Critical-Assembly Experiments

Technical Report · Fri Jun 10 04:00:00 EDT 1960

DOI:https://doi.org/10.2172/4143836· OSTI ID:4143836

Egen, Richard A. ^[1]; Hogan, William S. ^[1]; Dingee, David A. ^[1]; Chastain, Joel W. ^[1]

---

1. Battelle Memorial Inst., Columbus, OH (United States)

Critical experiments are described for the Variable Moderator Reactor (VMR), a reactor concept under investigation by American-Standard for the AEC. The VMR is light-water moderated and cooled and is fueled with slightly enriched uranium dioxide pellets loaded into aluminum tubes. The core consists of 37 hexagonal fuel cans each loaded with 61 fuel pins. The cooling water, which flows upward around the pins inside the fuel can, boils in passing through the core. Reactor control in the prototype will be achieved by varying the moderator height. The site, laboratory, and the critical assembly, including control and safety mechanisms, are described in detail. Special characteristics of the assembly pertinent to safety were calculated. The nuclear energy released and the average and maximum fuel temperatures resulting from step reactivity increases up to 2% Δ k/k are presented graphically for two cases. In the first case, fuel-temperature effects are considered to be the only shutdown mechanism; in the second radiolytic gas is considered to contribute to shutdown, in addition to fuel-temperature effects. The accident considered to be the maximum credible accident causes a step addition in reactivity of 1.5% Δ k/k. The nuclear-energy release is between 160 and 310 megawatt-sec depending on the assumed shutdown mechanisms. This accident does not cause any fuel to be vaporized (and probably none to be melted) and, hence, there does not appear to be a hazard from fission-product activity. It appears that this critical assembly program can be conducted with reasonable assurance of safe operation and that no public persons will be jeopardized by its operation.

• Research Organization: Battelle Memorial Inst., Columbus, OH (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• DOE Contract Number: W-7405-ENG-92
• NSA Number: NSA-14-018563
• OSTI ID: 4143836
• Report Number(s): BMI-1445
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCIDENTS
ALUMINUM
Analysis
BOILING
CONFIGURATION
CONTROL
CONTROL SYSTEMS
CRITICAL ASSEMBLIES
CRITICALITY
Critical Assemblies
Criticality
DECOMPOSITION
DIAGRAMS
ENERGY
ENVIRONMENT
EQUATIONS
EXCURSIONS
FLUID FLOW
FUEL CANS
FUEL ELEMENTS
LEVELS
Light Water Moderated Reactor
MEASURED VALUES
MELTING
MODERATORS
Nuclear Criticality Safety Program (NCSP)
OPERATION
PELLETS
REACTIVITY
REACTOR CORE
REACTOR SAFETY
REACTORS
SHUTDOWN
Safety
TEMPERATURE
TUBES
URANIUM DIOXIDE
VARIATIONS
VMR
Variable Moderator Reactor
WATER COOLANT
WATER MODERATOR