Showing papers by "Pacific Northwest National Laboratory published in 1973"

Plutonium Fuel Technology, Part II: Radiation Exposure from Plutonium in LWR Fuel Manufacture

Abstract: Personnel radiation exposure problems in fabricating and handling plutonium fuels are described. The effects of variations in plutonium isotopic composition, due to differences in reactor types and fuel exposure and the resultant combined effects on personnel radiation exposure, are also described. It is concluded that increased shielding will be required for plutonium fuel fabrication facilities when full-scale plutonium recycle is under way, due to the higher radiation levels associated with high exposure plutonium and to more restrictive personnel radiation exposure limits than those currently used. However, it should be possible to handle completed plutonium fuel assemblies containing high exposure plutonium without excessive personnel exposure and with a minimum of special handling procedures.

Criticality of Plutonium Nitrate Solutions Containing Borated Raschig Rings

Abstract: Experimental criticality data on borated raschig rings in plutonium nitrate solutions are presented for use in establishing criticality safety limits and in verifying calculational methods for thes...

Effects of Chronic 60Co (Gamma) Radiation, Dose Rate, Temperature, and Cohabitation on Population Performance of Flour Beetles

Abstract: This investigation concerned the population dynamics and the possible control of Tribolium confusum Jacquelin duVal and T. castaneum (Herbst) subjected to chronic irradiation. At 3 dose levels of 60Co gamma radiation (24, 49, and 170 R per day) 5 replicate populations of single species (20 pairs in each) and of mixed species (10 pairs of each species) were established in 5 g of food in lucite test tubes. Larvae, pupae, and adults were counted monthly and along with eggs were transferred to new food. Culture conditions were 25 and 32°C in 70–75% relative humidity. In general, at 25°C the single-species reproductive performance, measured as the number of larvae and adults, was impaired by exposure to radiation. Poorest performance appeared at 170 R per day; whereas, 24 and 49 R per day resulted in reduced, but comparable productivity. Larvae were more radiation-sensitive than adults. Numbers of adults reached zero more slowly than larvae at 170 R per day, indicating no adult replacement. Results were accentuated at 32°C. Responses to radiation of mixed- and single-species populations were comparable at 25°C. There was greater survival of larvae and adults in mixed-species populations at 32°C than at 25°C. Data from this experiment showed that 170 R per day dose rate was sufficient to stop larval development; but 49 R per day was not enough to eliminate flour beetle populations. The radiation effects on population performance were attributed to induced genetic aberrations rather than to physiological impairment. The feasibility of implanting radiation sources in a grain storage facility to control insects is discussed.

Biomedical probe using a fiber optic coupled scintillator

Abstract: A biomedical scintillation counter similar in size to a fiberoptic gastroscope was fabricated to count low concentrations of internal radioactivity. The probe was built specifically to count the uranium L x rays (average energy 17 keV) emitted in the decay of plutonium located in the tracheobronchial lymph nodes. Plutonium is found in the trachenbronchial lymph nodes due to translocation of inhaled insoluble plutonium compounds. Efforts with the scintillation technique resulted in a probe with higher sensitivity than a previously developed solid-state avalanche diode probe. Although the probe was developed specifically for counting plutonium, it can be readily applied to counting other isotopes with low energy photons such as /sup 131/I, /sup 125/I, / sup 197/Hg, /sup 67/Ga, /sup 133 /Xe, /sup 99m/Tc, etc. The physical features and the performance of the fiber optic coupled scintillation counter are described, and the probe is compared with similar solid-state probes. Previous fiber optic probes have been built for dosimetry; however, the present probe is designed for low background, low energy, high sensitivity photon counting. (WHK)

Radiation Damage Induced Time Delay in GaAs Lasers

Abstract: Fast-neutron irradiation induced time delays in the turn-on of the optical output pulse of diffused GaAs laser diodes have been observed. The results are explained using a double-acceptor model that predicts the delay's functional dependence on fluence and that also accounts qualitatively for the observed temperature dependence of the delay. Little neutron damage induced change occurs at LN2 temperature, where the delay is thought to be a result of the time required to establish the population inversion, the double-acceptor traps being inactive. At high temperature the increase in delay with fluence appears to be caused by introducing more traps at a rate proportional to the number already existing. A "pivot" operating point can be found at which the diode time delay is almost unaffected by damage to > 1014 n/cm2 (> 10 keV).