Radiation levelness measurement with

Screening measurements of incident response samples begin as soon as possible after sample receipt and logging. A necessary first step is prescreening to prevent a sample from being taken to a laboratory if its radionuclide content is unsuitably high for the usual controls of personnel radiation exposure and contamination of the analyst, the laboratory, and radiation detectors. External radiation is measured with conventional low-level radiation monitors that include the G-M detector and... 

The remaining measuring channels, located in a second chassis, measure radiation levels associated with operating specific experimental facilities. These channels are not required by Technical Specifications, but are described in the Safety Analysis Report. Each beam port has an associated radiation monitor channel, with the detector located on the Reactor Laboratory walls in line with the radiation beam that would be emitted if the beam ports were operated with plugs and external shields removed. A fifth channel detector is located beside the pneumatic tube send-receive station in room 43. This channel has a remote indicator, which provides both dose rate readout and alarm on high radiation level. All five of these detectors annunciate via the EXPERIMENTAL FACILITY RADIATION LEVEL HIGH annunciator when high alarm setpoints are exceeded. These are not connected to the external evacuation alarm. 

Radiation-Density Gauges Gamma radiation may be used to measure the density of material inside a pipe or process vessel. The equipment is basically the same as for level measurement, except that here the pipe or vessel must be filled over the effective, irradiated sample volume. The source is mounted on one side of the pipe or vessel and the detector on the other side with appropriate safety radiation shielding surrounding the installation. Cesium 137 is used as the radi-... 

Spectral Gamma Ray Log. This log makes use of a very efficient tool that records the individual response to the different radioactive minerals. These minerals include potassium-40 and the elements in the uranium family as well as those in the thorium family. The GR spectrum emitted by each element is made up of easily identifiable lines. As the result of the Compton effect, the counter records a continuous spectrum. The presence of potassium, uranium and thorium can be quantitatively evaluated only with the help of a computer that calculates in real time the amounts present. The counter consists of a crystal optically coupled to a photomultiplier. The radiation level is measured in several energy windows. 

The downward spectral irradiance data [Ed(X), the ambient UV radiation] were generated with the atmospheric model of Frederick and Lubin (27) and ozone levels measured during the course of this study (J.E. Frederick, pers. commun.). The relative degree of UV enhancement (%ENH) for each chamber was calculated as follows ... 

A y-ray source (e.g. 137Cs, Co, 226Ra) is frequently used for liquid level measurement and for liquid and solid level detection. The absorption of the y radiation varies with the thickness x and nature of the absorbing material between the source and the detector according to the Beer-Lambert law, viz ... 

A blood-volume determination was carried out on a patient by injection with 20.0 mL of blood that had been radioactively labeled with Cr-51 to an activity of 4.10 /tiCi/mL. After a brief period to allow for mixing in the body, blood was drawn from the patient for analysis. Unfortunately, a mix-up in the laboratory prevented an immediate analysis, and it was not until 17.0 days later that a scintillation measurement on the blood was made. The radiation level was then determined to be 0.009 35 /rCi/mL. If 51Cr has fj/2 = 27.7 days, what is the volume of blood in the patient ... 

On hard-to-handle services, such as the fluidized-bed level measurement in combustion processes, there is little choice but to use radiation gauges. On slurry and sludge services, d/p units with extended diaphragms eliminate the dead-ended cavity and bring the sensing diaphragm flush with the inner surface of the tank. Other level transmitters that can be considered for hard-to-handle services include the capacitance/RF, laser, radar, sonic, and TDR types. 

Fig. 13.4. Example of a discharge with silicon evaporation from a test limiter made of Si-doped CFC (SEP NS31). The figure shows the time traces of the local silicon fluxes from the limiter (Si/D), the line-integrated radiation of Si XII emission, the local surface temperature of the limiter measured at the location of maximal power loading, the energy loss due to plasma radiation (Prad), the radiation level 7 = Pia.d/P, the diamagnetic energy Fdia and the convective power on the test limiter P — Praa, respectively...

A radiological dispersal device (RDD) explodes, contaminating 10 square miles with radioactive cobalt (Co-60). The highest measured radiation level is about 10 meters from the site of the explosion and it reads about 150 mrem/hr. The average radiation dose through the affected area is 5 mrem/hr, and about 500,000 people live and work in this area. The device itself consisted of 1,000 pounds of explosive, set off near City Hall. 

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