IMPACT OF TARGET MATERIAL ACTIVATION ON PERSONNEL EXPOSURE AND RADIOACTIVE CONTAMINATION IN THE NATIONAL IGNITION FACILITY
Detailed activation analyses are performed for the different materials under consideration for use in the target capsules and hohlraums used during the ignition campaign on the National Ignition Facility. Results of the target material activation were additionally used to estimate the levels of contamination within the NIF target chamber and the workplace controls necessary for safe operation. The analysis examined the impact of using Be-Cu and Ge-doped CH capsules on the external dose received by workers during maintenance activities. Five days following a 20 MJ shot, dose rates inside the Target Chamber (TC) due to the two proposed capsule materials are small ({approx} 1 {micro}rem/h). Gold and depleted-uranium (DU) are considered as potential hohlraum materials. Following a shot, gold will most probably get deposited on the TC first wall. On the other hand, while noble-gas precursors from the DU are expected to stay in the TC, most of the noble gases are pumped out of the chamber and end up on the cryopumps. The dose rates inside the TC due to activated gold or DU, at 5 days following a 20 MJ shot, are about 1 mrem/h. Dose rates in the vicinity of the cryo-pumps (containing noble 'fission' gases) drop-off to about 1 mrem/h during the first 12 hours following the shot. Contamination from activation of NIF targets will result in the NIF target chamber exceeding DOE surface contamination limits. Objects removed from the TC will need to be managed as radioactive material. However, the results suggest that airborne contamination from resuspension of surface contamination will not be significant and is at levels that can be managed by negative ventilation when accessing the TC attachments.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 974385
- Report Number(s):
- LLNL-JRNL-414639; ITPSBD; TRN: US1002311
- Journal Information:
- IEEE Transactions on Plasma Science, Vol. 38, Issue 3; ISSN 0093-3813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
61 RADIATION PROTECTION AND DOCIMETRY
CONTAMINATION
CRYOPUMPS
DEPLETED URANIUM
DOSE RATES
FIRST WALL
FISSION
GASES
GOLD
IGNITION
MAINTENANCE
PARTICLE RESUSPENSION
PERSONNEL
RADIOACTIVE MATERIALS
RARE GASES
SURFACE CONTAMINATION
TARGET CHAMBERS
TARGETS
US NATIONAL IGNITION FACILITY
VENTILATION