MEASUREMENT OF RADIATION LEVEL OF THE 10 kc HOT CAVE. Report No. 11

Technical Report · Fri Jul 01 04:00:00 EDT 1960

OSTI ID:4108619

The shielding of the 10-kilocurie Hot Cave at the JAERl was so designed that the maximum radiation intensity is less than 30 mr per 48-hr week (equivalent to 0.63 mr/hr) on any outside vertical wall and less than 150 mr per 48-hr week above the roof, when the 10-kilocurie Co/sup 60/ -ray source is located at the center of the cell. The measurement of the field intensity was made by G-M and scintillation type: survey meters. In the preliminary test using 500-c Co/sup 60/ source, several weak points such as the manipulator through-tube and the shielding around the storage well were detected. To reduce the radiation leakage, an additional lead-shielding plug of 18 cm in thickness was inserted in a through-tube, and an iron shield box of 5 cm in thickness was attached around the tube at the hot side. For the storage cell, lead blocks of 10 cm in thickness were placed over the floor. After reducing the leakage of the shielding, radiation leak tests with 10-kilocurie Co/sup 60/ source were carried out. The source was located at 70 and 175 cm above the floor at the center of each cell. The radiation levels on the outer surface of the cave did not exceed the specified limit except at two points, the manipulator through-tube and the periphery of the steel door on the roof. The distribution of the radiation intensity scattered from the manipulator through-tube with the lead shield of 38 cm in thickness was measured. Since this radiation is a very sharp directional beam, an operator may work under little influence of the scattered radiation. In general, the radiation levels at all positions outside the cave are at the safe level when the 10-kilocurie Co/sup 60/ source is in use. (auth)

• Research Organization: Japan Atomic Energy Research Inst., Tokyo
• NSA Number: NSA-15-004164
• OSTI ID: 4108619
• Report Number(s): JAERI-1011
• Country of Publication: Japan
• Language: English

Related Subjects

AIR
BEAMS
COBALT 60
DETECTION
DISTRIBUTION
GAMMA RADIATION
GEIGER-MUELLER COUNTERS
HEALTH AND SAFETY
IRON
LEAD
MEASURED VALUES
PERSONNEL
PLANNING
QUANTITY RATIO
RADIATION DOSES
RADIATION PROTECTION
RADIOACTIVITY
REMOTE HANDLING
SAFETY
SCATTERING
SCINTILLATION COUNTERS
SEALS
SHIELDING
STANDARDS
STEELS
STORAGE
SURFACES
TESTING
TUBES
USES