On-line liquid-effluent monitoring of sewage at Lawrence Livermore National Laboratory

LLNL's sanitary sewer system is a possible route for the escape of toxic materials. Liquid effluents are released to Livermore's sanitary sewer system and the effluent is treated at the Livermore Water Reclamation Plant (LWRP). The plant is a secondary-treatment operation that returns most of the water to the San Francisco Bay via a transport pipeline. The remaining portion is used for irrigating vegetation along the roadways and a local golf course. An automatic on-line, sewage-effluent-monitoring system has been developed that diverts a representative fraction of the total waste stream leaving the site. This portion is monitored for pH, radiation, and heavy metals as it passes through a detection assembly. The assembly consists of an industrial pH probe, two NaI radiation detectors, and an x-ray fluorescence metal detector. A microprocessor collects, reduces, and analyzes the data to determine if the levels are acceptable by established environmental limits

REM meter for pulsed sources of neutrons

A rem meter was constructed specifically for measuring neutrons produced by fusion experiments for which the source pulses last 10 ms or longer. The detector is a /sup 6/Li glass scintillator, 25.4 mm in diameter and 3.2 mm thick, surrounded by 11.5 cm of polyethylene. This detector has a sensitivity of 8.5 x 10/sup 4/ counts/mrem. The signals from this fast scintillator are shaped using a shorted delay line to produce pulses that are only 10 ns long so that dose equivalent rates up to 12 mrem/s can be measured with less than a 1% counting loss. The associated electronic circuits store detector counts only when the count rate exceeds a preset level. When the count rate returns to background, a conversion from counts to dose equivalent is made and the results are displayed. As a means of recording the number of source pulses that have occurred, a second display shows how many times the preset count rate has been exceeded. Accumulation of detector counts and readouts can also be controlled manually. The unit will display the integrated dose equilavent up to 200 mrem in 0.01 mrem steps. A pulse-height discriminator rejects gamma-ray interactions below 1 MeV, and the detector size limits the response above that energy. The instrument can be operated from an ac line or will run on rechargeable batteries for up to 12 hours

Neutron spectrum measurements for radiation protection purposes

The energy spectra of low-intensity neutron sources used for calibrating personnel neutron dose-rate meters and dosimeters and for characterizing the neutron fields to which personnel are exposed were measured. Several detector-analyzer systems that will measure in the energy range 50 keV to 20 MeV at intensities from 10/sup -1/ to 10/sup 5/ n/cm/sup 2/-s are described. The systems include NE213 and stilbene organic scintillators as well as H/sub 2/, /sup 3/He, and CH/sub 4/ proportional counters. Also described are pulse-height analysis and pulse-shape discrimination systems. An unfolding code, NUTSPEC, reduces the pulse-height data to an absolute differential neutron flux phi(E) for the above detectors. The code uses a derivative unfolding method for the scintillation detectors, and for the proportional counters it calculates a response matrix and uses an iterative unfolding method to determine phi(E). The unfolded flux distribution combined with published conversion factors produces differential neutron dose-equivalent and kerma rates. Spectral segments obtained with different detectors from several measurements merge into a single differential flux spectrum over the range 50 keV to 20 MeV, together with the corresponding differential kerma and neutron dose-equivalent distributions. Also reported are spectrum measurements near /sup 252/Cf and /sup 238/PuBe sources with various moderators

On-line monitoring of toxic materials in sewage at the Lawrence Livermore Laboratory

It is becoming increasingly important for industry to prevent releases of potentially toxic material to the environment. The Lawrence Livermore Laboratory has developed a system to monitor its sewage effluent on a continuous basis. A representative fraction of the total waste stream leaving the Plant is passed through a detection assembly consisting of an x-ray fluorescence unit which detects high levels of metals, sodium iodide crystal detectors that scan the sewage for the presence of elevated levels of radiation, and an industrial probe for pH monitoring. With the aid of a microprocessor, the data collected is reduced and analyzed to determine whether levels are approaching established environmental limits. Currently, if preset pH or radiation levels are exceeded, a sample of the suspect sewage is automatically collected for further analysis, and an alarm is sent to a station where personnel can be alerted to respond on a 24-hour basis. In the same manner, spectral data from the x-ray fluorescence unit will be routed through the 24-hour alarm system as soon as evaluation of the unit is complete. The design of the system and operational experience is discussed

Determination of continuous gamma-ray spectra over the energy range 0. 1 to 8 MeV. [RETECTUR code]

An experimental facility was established at LLL to characterize radiation fields produced by a variety of sources and transmitted through various shielding materials. Specific techniques for acquiring and reducing continuous gamma-ray energy spectra are discussed including NaI(Tl) detectors. Use of several detector sizes allowed study of a wide variety of source intensities and calculation of response matrices for a number of collimated detector configurations. A computer program to perform the data reduction by an iterative unfolding process is described. The reduction technique discloses the continuous gamma-ray energy spectrum over the range 0.1 to 8 MeV as opposed to the traditional peak intensity analysis. 11 references

On-line liquid-effluent monitoring of sewage at Lawrence Livermore National Laboratory

An automatic on line sewage effluent monitoring system has been developed. A representative fraction of the total waste stream leaving the site is monitored for pH, radiation, and metals as it passes through a detection assembly. This assembly consists of an industrial pH probe, NaI radiation detectors, and an x-ray fluorescence metal detector. A microprocessor collects, reduces and analyzes the data to determine if the levels are acceptable by established environmental limits. Currently, if preset levels are exceeded, a sample of the suspect sewage is automatically collected for further analysis, and an alarm is sent to a station where personnel can be alerted to respond on a 24-hour basis. Since at least four hours pass before LLNL effluent reaches the treatment plant, sufficient time is available to alert emergency personnel, evaluate the situation, and if necessary arrange for diversion of the material to emergency holding basins at the treatment plant. Information on the current system is presented, and progress is reported in developing an on-line tritium monitor as an addition to the assembly