ISOTOPIC COMPOSITION OF CZT DETECTORS VERIFICATION
ISOTOPIC COMPOSITION OF CZT DETECTORS SERIES

Metallic corrosion products from surfaces in the coolant circulation loop are brought into the reactor core by coolant circulation. Locating and tracking crud in pipes and valves Measurements at different angles localized the hot spot in three dimensions.ĥ. The image below shows a source within a shipping container.

ISOTOPIC COMPOSITION OF CZT DETECTORS SERIES

The H series can also be used to inspect received shipping containers to better understand the isotopes within, and know where in the container they will be. That point can then be metered to check if it exceeds the authorized dose limit. In a single measurement, the detector will locate the hottest point on the box, from its perspective. H100 and H400 have been used to inspect outgoing shipping containers to confirm their contents and shielding. H100 and H400 are also used to find hot particles on equipment and scaffolding, preventing personal-contamination events.Ĥ. A quick image using H100 pinpointed the location of the discrete radioactive particles, which were then removed. These had not been identified before with a survey meter, though it was known that the count rate was elevated there.

For example, one plant discovered that a few hot Cs-137 particles were painted into a floor. However, by imaging the entire region in a single measurement, a hot spot will appear over the particle. It can sometimes be hard to find discrete radioactive particles with a survey instrument because one must put the probe directly over the discrete radioactive particle and move slowly enough to tell that the count rate is elevated there. Adding more shielding here won't reduce dose as much as shielding the other direction.ģ. It is clear that the addition of shielding reduces the dose from one direction below that from another hot spot coming from the room above. For instance, the images below show the same region with and without shielding. Furthermore, gaps in the shield can be identified through the image. The distribution of gamma rays from each isotope can be measured before and after a shield is added to help validate its effectiveness. The H100, H400, or P100 can help to verify the adequacy of temporary shielding by identifying the primary contribution to the dose from each isotope. In some situations, ALARA mandates that shields be installed prior to personnel working in the area.

ISOTOPIC COMPOSITION OF CZT DETECTORS VERIFICATION

Verification of temporary shielding performance By replacing the pump seals, tungsten was removed, lowering the dose rate such that routine non-outage maintenance could be completed in that area of the plant.Ģ. On further investigation, the tungsten was found to be from pump-seal material that became activated in the coolant. This was responsible for elevating dose rates in a certain area of the plant such that maintenance could only be completed during an outage. In a third example, the H100 was used to see emission lines from radioactive tungsten coming from specific pipes. Unlike previous work where this hot spot had not been identified, the operator was able to lay down shielding on the floor to reduce the dose to workers. The H100 was positioned to view the area and it was discovered that a pipe segment under the floor was producing most of the dose, not the piping unit as originally expected. However, it wasn't clear which part was responsible for most of the dose. In another example, survey measurements showed that a piping unit was radioactive. Thus, the pit could be cleaned before work progressed.

H100 can also determine the isotopic composition of each hot spot. Moving the H100 to the other side of the cavity, which shields the system from the drain direction, another, unexpected, source term of the wall of cavity was identified. In the first measurement (first picture), the drain in the far left corner was identified as a primary contributor to the source term. These pictures were taken at the side of a reactor cavity before work was performed in it. The H100 or H400 gamma-ray camera can be used to locate the primary source(s) of radiation before work will be performed in some area. How might I use H3D detectors at my plant?

Isotopic composition of czt detectors