HEALTH PHYSICS FOLLOWING A NUCLEAR EXCURSION: THE LRL INCIDENT OF 26 MARCH 1963
On March 26, 1963 at approximately 0000 hr a nuclear excursion occurred in a shielded vault designed for critical assembly experiments. The excursion was estimated at 4 x 10/sup 17/ fissions, and was followed by oxidation of the enriched U metal in the assembly. The fire was observed via closed circuit TV; later entry established that burning was limited to the assembly Nearby combustibles did not burn or scorch. Disaster plans were immediately implemented to determine radiation exposures to personnel directly involved, the possibility of recurring criticality, and the extent of release of radioactive materials to the laboratory and to the off-site environment. Air and surface contamination levels were determined in the building housing the vault and at other points within the laboratory perimeter. Air, vegetation, and soil samples, obtained within hours following the excursion, were analyzed for fission product and alpha activity fallout. Results indicated the release of small amounts of short-lived, high-yield gaseous fission products and their daughters. No detectable alpha activity was released to the environment. The maximum exposure to any of the four persons in the building at the time was 120 mrems penetrating radiation. All neutron exposures were less than detectable limits, i.e., 50-mrem fast neutrons and 1-mrem thermal neutrons. Urinalyses, nasal wipes, and thyroid scans were all negative, indicating no internal exposure. An air sample taken from within the vault 57 hr after the excursion showed levels of approximates 2 x 10/ sup -6/ mu C/cm/sup 3/ of short-lived fission products. Radioactive decay and changing the vault air reduced these levels to below MPC values. The air exhausted from the vault was filtered and scrubbed with caustic before release to the atmosphere The initial vault entry was made to evaluate the possibility of a further excursion. The gross amounts of all fissile material were removed before decontamination operations were begun The building, exclusive of the vault, was reoccupied 6 days after the incident. This incident reaffirms the value of carefully designed vault facilities for critical assembly work. (auth)
- Research Organization:
- Univ. of California, Livermore
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-016242
- OSTI ID:
- 4067035
- Journal Information:
- Health Physics (England), Vol. Vol: 10; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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AIR
ALPHA DETECTION
BODY
BUILDINGS
CLEANING
COMBUSTION
CONTAMINATION
CRITICAL ASSEMBLIES
CRITICALITY
DECAY
DECONTAMINATION
ENRICHMENT
ENVIRONMENT
FALLOUT
FILTERS
FISSION
FISSION PRODUCTS
GASES
IRRADIATION
LEVELS
METALS
MPC
NEUTRONS
NUCLEAR EXPLOSIONS
OXIDATION
PERSONNEL
PLANTS
QUANTITATIVE ANALYSIS
RADIATION DOSES
RADIATION PROTECTION
RADIOACTIVITY
SAFETY
SAMPLING
SHIELDING
SURFACES
TELEVISION
TESTING
THERMAL NEUTRONS
THYROID
URANIUM
URINE