A significant amount of piping is embedded in nuclear power plants (NPPs). In decommissioning these materials must be removed and cleaned. It can then be evaluated for radioactivity content below the release level. MARSSIM presents Derived Concentration Guideline Levels (DCGLs) that meet release guidelines. Calculating DCGL requires scenarios for the placement of embedded pipe and its long-term potential location or use. Some NPPs choose to keep the embedded pipes in the building. Because others will dismantle the building and dispose of the piping in-situ, determining the disposal option for embedded piping requires the use of measurement techniques with the sensitivity and accuracy necessary to measure the level of radioactive contamination of embedded piping and meet DCGL guidelines. The main measuring detectors used in NPPs are gas counters that are remotely controlled as they move along the inside of the pipe. The Geiger-Mueller (GM) detector is a detector commonly used in the nuclear field. Typically, this GM detector used 3-detectors that cover the entire perimeter of the pipe and are positioned at 120-degrees to each other. This is called a pipe crawler. It is very insensitive to gamma and X-ray, only measures beta-emitter and does not provide nuclide identification. The second method is a method using a high-resolution gamma-ray detector. Although not yet commercialized in many places, embedded piping is a scanning method. The technique only detects gamma-emitting nuclides, but some nuclides can be identified. Gamma-ray scanning identifies the average concentration per pipe length by the detector collimator. It is considerably longer than a pipe crawler. In addition, several techniques, including direct measurement of dose rate and radiochemical analysis after scraping sampling, are used and they must be used complementary to each other to determine the source term. Expensive sampling and radiochemical analysis can be reduced if these detectors are used to measure the radioactivity profile and to perform waste classification using scaling factor. In the actual Trojan NPP, a pipe crawler detector was used to survey the activity profile in a 26 foot of an embedded pipe. These results indicate that the geometric averaging of the factors and a dispersion values for each nuclide are constant within the accuracy factors. However, in order to accurately use the scaling factor in waste classification, it must have sample representativeness. Whether the sample through smear or scraping is representative of the radionuclide mixture in the pipe. Since the concentration varies according to the thickness of the deposit and depending on the location of the junction or bend, a lot of data are needed to confirm the reliability of the nuclide mixture. In this study, the reliability of the scaling factor, sampling representativeness and concentration measurement accuracy problems for waste classification in decommissioning NPP were evaluated and various techniques for measuring radioactive contamination on the inner surface of embedded pipes were surveyed and described. In addition, the advantages and limitations of detectors used to measure radioactivity concentrations in embedded piping are described. If this is used, it is expected that it will be helpful in determining the source term of the pipe embedded in the NPPs.

With a growing concern of greenhouse gas (GHG) emissions due to climate change, many activities and efforts onthe greenhouse gas reduction have been implemented in solid waste sectors. Since recycling is the major managementoption for solid waste in Korea, it is important to estimate the reduction of the greenhouse gas emission during recyclingprocesses. In this study, two common methodologies, Prognos method of EU and waste reduction model (WARM) methodof USA, have been critically reviewed and compared to estimate the reduction for recycling of waste paper in terms ofsystem boundary, recycling processes, and emission factors. As a common point of two methodologies, the reductionfactors for the paper recycling have been developed by subtracting the recycled product emissions from the virgin productemissions to get the greenhouse gas savings. While the recycling losses and transportation are considered in twomethodology development, there are a number of differences between the methodologies in system boundary,transportation distance and forest carbon sequestration. As a result, it caused the difference in final greenhouse gasreduction factor of paper recycling. The reduction factor was −820kgCO2eq/ton in Prognos method, while −3,891kgCO2eq/ton was found in the WARM method. When both methods were applied to recycling of waste paper in Korea,the greenhouse gas reductions by the Prognos method and the WARM method were found to be 3,485.2tCO2eq/day and2,248.8tCO2eq/day, respectively. When the carbon sequestration by forest is considered in the WARM method, thereduction rate was estimated to be 16,538.3tCO2eq/day. The main reasons for such difference can be attributed to systemboundary and forest carbon sequestration. Especially, forest carbon sequestration can be an important factor in Korea thatusually manufactures papers from imported pulp from abroad. This study implies that the applications and results of bothmethods to estimate greenhouse gas reduction by waste recycling should carefully reviewed and acknowledged beforeuse due to the different assumptions and results that are anticipated.