Figure 18 - uploaded by Benno Bucher
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Vehicle equipped with gamma spectrometric equipment (left) and measurement with high pressure ionisation chamber (right).
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The flights of the civil (ARM23c) and military (ARM23m) parts of the exercise were performed between June 19 th and 23 rd and between September 11 th and September 15 th , respectively. The measuring system RLL001 was employed for all measurements. As usual, during the civil exercise the environs of some of the Swiss nuclear power plants were screened, on behalf of the Swiss Nuclear Safety Inspectorate (ENSI). At the site of the nuclear power plant Gösgen (KKG) with its pressurized water reactor, the activation products of the primary coolant loop are kept in the well shielded reactor building, thus generating no elevated readings neither on the premises nor in the vicinity of the power plant. The nuclear power plant of Mühleberg (KKM) is now being decommissioned. During this phase, activated components are temporarily stored and processed on the plant premises. The dose rate produced by these components, easily detected and identified with the Swiss airborne gamma spectrometry system, is nevertheless very modest and closely monitored by the Swiss Nuclear Safety Inspectorate (ENSI). Search exercises for radionuclide sources were performed in both parts of ARM23. The operational software of the RLL systems was able to detect the radionuclide sources placed in military training areas. The Man-Made Gross-Count (MMGC) ratio demonstrated a good sensitivity for the identification of radionuclide sources. Nevertheless, a weak radionuclide source placed in the field of view of the helicopter (300 m x 300 m at a ground clearance of 100 m) together with a much stronger radionuclide source emitting higher energy pho-tons was obscured due to Compton scattered photons and therefore could not be detected. Measurements of two teams using drones equipped with radiation monitors demonstrated that low flying drones (ground clearance below 10 m) can be a valuable and complementary tool to identify sources and to further reduce the target area to be searched with ground teams. An altitude profile over Lake Constance confirmed the already observed influence of airborne radon progeny on the determination of cosmic and background corrections. Background flights were performed over several Swiss regions. Besides attenuation effects of water bodies, variations of natural radionuclide content could be observed. A new flight strategy in alpine topography was tested near the Swiss mountain Chrüz. Following contour lines of the topography reduces the necessity for drastic flight altitude changes compared to the parallel line pattern normally used, but is much more challenging for the pilots.
The flights of the civil part (ARM21c) of the exercise were performed between June 28 th and July 2 nd and the flights of the military part (ARM21m) were performed between August 30 th and September 2 nd , 2021. Both parts of the exercise included the measurement of an altitude profile over Lake Neuchâ-tel with sufficient altitude range to determine the slope of the altitude dependent cosmic correction. According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Gösgen (KKG) and Mühleberg (KKM) were surveyed, the former extended with an area to the southeast of the power plant. The measurements showed no artificial radionuclides outside of the plant premises. The series of background measurements over Swiss cities was continued with flights over Frauenfeld, Lugano, Nyon and Wil. As a follow-up of the Caesium deposition in the wake of the Chernobyl accident, measurements were performed over areas in western and southern Switzerland. Residual 137 Cs activity can still be detected in the vicinity of Lugano and several other sites tested during ARM21 as a follow-up of the Chernobyl deposition. Comparison to results of ground measurements , maps published in the scientific literature and previous airborne measurements yielded reasonable agreement to the measurement results. Detector RLL001 used in ARM21c continues to operate as specified. Problems with one NaI(Tl) crystal of detector RLL004 used during ARM21m indicates that not all of the crystals with poor quality have been identified in previous exercises.
The flights of the civil (ARM22c) and military (ARM22m) parts of the exercise were performed between June 13th and 17th and between September 5th and September 9th, respectively.
Both parts of the exercise included the measurement of altitude profiles. Two profiles were measured during ARM22c over Lake Thun and one profile during ARM22m over Lake Neuchâtel with sufficient altitude range to determine the slope of the altitude-dependent cosmic correction. The altitude profile over Lake Neuchâtel showed a clear deviation from the expected profile, suggesting a massive influence of airborne radon progeny on the result.
According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Beznau (KKB) and Leibstadt (KKL), the Paul Scherrer Institute (PSI) and the intermediate storage facility (ZWILAG) were surveyed with an extension of the measuring area into German territory, following a request of German authorities. The site of the former Lucens reactor was measured and found unobtrusive in the measured data.
Background flights were performed over several Swiss cities, regions and valleys. Besides attenuation effects of water bodies, variations of natural radionuclide content could be observed. Remains of the Chernobyl deposition were detected near the French border and in southern Switzerland.
The flights of the civil part ARM20c of the exercise were performed between June 12 th and June 19 th , 2020. According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Beznau (KKB) and Leibstadt (KKL) and the nuclear facilities of the Paul Scherrer Institute (PSI) and the Zwischenlager Würenlingen AG (Zwilag) were surveyed. The measurements showed no artificial radionuclides outside of the plant premises. Additional measurements were performed between Brugg and Zurich, over the lakeshore of Lake Zurich and over the town of St. Gallen. An altitude profile over Lake Thun was used to quantify the influence of cosmic rays and the helicopter background on the measurement system. A source search exercise and an intercomparison with ground measurements was performed on Thun military training ground. A short report of the measurement results of ARM20c was placed on the NEOC website https://www.naz.ch/ on June 19 th , 2020. The flights of the military part ARM20m of the exercise were performed from November 9 th to November 13 th. ARM20m focused on a fine-meshed survey of a large area north of Lake Geneva, adding to the aeroradiometric coverage of Switzerland. The radiological maps show the influence of attenuating water layers and the underlying geology on the measurement results. A flight near Mont Pelé checked on the 137 Cs activity remaining after the Chernobyl accident in 1986. Several changes were bundled into the present report. The data evaluation was performed with a new software developed in the .net environment. Raw data, evaluated data and parameters used in the evaluation for each measuring area are stored together in a single text file using the ERS 2.0 format description (see PSI report 18-04). The colour gradient scale used in previous reports was replaced with a discrete colour scale defined by the Swiss Expert Group for Aeroradiometrics (FAR). The reference soil mass was switched from dry weight to wet weight, as the importance of radio-analytical laboratory measurements as reference is diminished in comparison with in-situ gamma-spectrometric ground measurements .
Results of the airborne gamma spectrometry measurements within the framework of the 2019 Swiss exercise ARM19.
The measurement flights of the exercise ARM18 were performed between May 28th and
June 1st, 2018. The exercise was organized by the National Emergency Operations Centre
(NEOC) under coordination from the Expert Group for Aeroradiometrics (FAR). Representatives of KompZen ABC-Kamir participated both in the exercise and performed separate measuring flights.
According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Beznau (KKB) and Leibstadt (KKL) and the nuclear facilities of the Paul Scherrer Institute (PSI) and the Zwischenlager Würenlingen AG (Zwilag) were surveyed. The measurements showed no artificial radionuclides outside of the plant premises. On request of German authorities, the measuring area was extended into German territory. In this area, a dose rate anomaly associated with Th-232 activity in a mineral processing plant could be identified.
The series of radiological background measurements over Swiss cities was complemented with measurements over Solothurn, Fribourg and Yverdon-les-Bains. The measurement in the vicinity of Yverdon-les-Bains was used to directly compare the evaluation software of the old ARM system (MGS32) to the proprietary software of the manufacturer of the RLL system (Mirion).
The international exercise CONTEX18 was performed in the International Atomic Energy
Agency (IAEA) Response and Assistance Network (RANET) framework between June 19th
and 21st in northern Denmark, coordinated by the Danish Emergency Management Agency (DEMA). It provided the opportunity to measure an altitude profile over the North Sea with low airborne radon progeny concentrations. A clear difference to measurements over Swiss inland lakes was observed. This difference was used for investigating a potential method to compensate for the influence of airborne radon progeny on the measurement of U-238 activity concentrations. The organisers of the exercise placed several sources of different radionuclides and activities in the exercise area, challenging the performance of airborne detection. A method using maxima of the man-made-gross-count(MMGC)-ratio to define points which should be inspected more closely was developed. The spectra of these points of interest were inspected in detail and led to the identification of Cs-137, Ir-192, Tc-99m, Se-75 and In-111 sources.
Measurements around Mont Vully on behalf of the University of Basel could not clearly locate small scale anomalies of U-238 concentrations due to the field of view of the airborne measurements and depth of the peat layer containing elevated U-238 concentrations.
Measurements along a transversal showed expected results due to flight altitude and attenuation of photons by water bodies.
Description of airborne Gamma spectrometry Systems of participating Teams, Results of the measurements, Comparison of the results of the different Teams and comparison with ground measurements, suggestions for a version 2.0 of ERS data Format.
The measurement flights of the exercise ARM16 were performed between June 27 th and July 1 st , 2016. The exercise was organized by the National Emergency Operations Centre (NEOC) under coordination from the Expert Group for Aeroradiometrics (FAR). Representatives of KompZen ABC-Kamir participated with a second Super Puma helicopter carrying the prototype of a new airborne gamma-spectroscopy system (RLL) in parts of the exercise. According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Beznau (KKB) and Leibstadt (KKL) and the nuclear facilities of the Paul Scherrer Institute (PSI) and the Zwischenlager Würenlingen AG (Zwilag) were surveyed. Both reactor blocks of KKB were in maintenance shutdown during the flights. The series of radiological background measurements over Swiss cities was complemented with measurements over Luzern, Emmen, Cham, Baar and Zug. A permanent dose rate probe of the Swiss NADAM Network near Vicosoprano measures the highest values observed in this network. The vicinity of the probe was inspected with airborne gamma-spectrometry and the elevated dose rate was confirmed and could be attributed to elevated concentrations of natural radionuclides. The emergency exercise LAURA, consisting mainly of the search for radioactive sources, was conducted at Emmen military airfield in cooperation with local first responders. Several measuring flights were performed to test the evaluation procedures. Especially the parameters for background and altitude corrections were inspected.
