P-6a-310 Radiation Protection at the new High Flux Reactor FRM-II E. Finke1, K. Böning1, U. Bork2 , K.-D. Wünsch3 1 ZBE FRM-II Bau, Technische Universität München, 2 Siemens/KWU NLL5, Erlangen 3TÜV Bau und Betrieb GmbH INTRODUCTION A new high flux reactor with a thermal neutron flux of about 8E+14 [n/s cm2].is under construction in Garching near Munich, Bavaria, and is to start operation in 2001. Its core with the power of 20 MWth consists of one fuel element only, cooled by light water, and is surrounded by a moderator tank filled with heavy water. A great number of horizontal beamtubes are installed as well as vertical channels to allow for different kinds of installations, for example, a hot, a cold and an ultracold neutron source, and several irradiation facilities. The description of the radiation protection concept takes into account the utilization envisaged, the demand of the regulations as well as the experience from the highflux reactor ILL in Grenoble and the Orphee reactor in Saclay. The radiation protection concept includes • the organisation of radioprotection • the classification of the different rooms • radiation monitoring of persons, systems, emission and environment also in case of incidents and accidents • usage and storage of radioactive samples and used parts • documentation. More detail is given on the classification of the different rooms and radiation monitoring of persons, systems, emission and environment also in case of incidents and accidents. THE NEW RESEARCH NEUTRON SOURCE FRM-II The new research neutron source FRM-II in Garching is under construction since 1996 and will start operation in 2001. It will serve for a multitude of different scientific and technical investigations for German and foreign scientists (1-4). Figure1: Model of the future neutron source FRM-II: Main Data of the Plant: top left reactor building with entrance hall, • reactor type: swimmingpool reactor with bottom right the existing research reactor München moderator tank FRM ("atomic-egg"), structurally combined by the • useable neutron flux: max 8.1014 n/cm2/s new neutron guide hall. thermal • thermal power: 20 MW • reactor core: compact core, consisting of one single fuel element. The reactor core with the fuel element is located in a heavy water moderator tank, which also contains various experimental installations and neutron beam tube heads. Room for experiments is provided in the experimental hall, arranged close to the reactor pool, and in the neutron guide hall. Figure 1 shows the model of the reactor building. Experiments of basic scientific research are foreseen in the fields of material science, physics, chemistry, biology and medicine. Further applications are planned for radiation therapy, neutron activation analysis, transmutation doping of silicon, production of radio- pharmaceutical products or technical preparations. DEFINITION AND SURVEY OF THE DIFFERENT AREAS OF RADIATION PROTECTION The whole area of the FRM-II up to the outer fence is regarded as supervised area. This survey area is subdivided into different controlled areas: • the reactor building (some areas are only supervised areas) P-6a-310 • a part of the basement below the neutron guide hall • a part of the stack Permanently or temporarily restricted areas can be installed on request (for example hot cell, filling station for resins). The neutron guide hall, directly connected to the reactor building belongs to the supervised area. Here local controlled areas can be installed on request (for example in the neutron guide tunnel). Experimental installations are placed inside the reactor building near the reactor in the experiment hall and within the reactor hall and outside the reactor building in the neutron guide hall. The safety installations for electrical and ventilation control are installed inside the reactor building. Systems containing radioactive materials are located totally within the controlled area. The experiments (experimental hall) and the reactor systems (reactor hall and basement) are separated by different ventilation systems. A further classification is done by subdividing the controlled area in zones of defined dose rate and in zones reserved for different operations. The survey of the different zones of radioprotection is done by the radioprotection staff of the FRM-II. The controlled areas are only to be entered and left by the designated entries and exits. The staff also marks the controlled areas as well as the defining, fencing and marking of the exclusion areas. PERSONAL MONITORING Personal monitoring is performed by the following means: • Measuring and evaluating of the personal doses • Monitoring and controlling the observation of the dose limits • Monitoring of the contamination • Monitoring the incorporation • Medical monitoring and instruction • Recording of the radiation protection passports • Checking, calibration and repair of the radiation protection measurements The occupationally exposed persons are equipped with two gammasensitive dosemeters, an official one and one which can be read off directly. If necessary, there is an additional neutron sensitive dosemeter. In accordance with the respective activities dosimeters for extremities (for instance finger ring dosimeters) are issued. Shieldings take care that the limits of the radioprotection ordinance for personal dose in case of permanent installations are not surpassed. The concentration of radioactive gases and particles in the air is controlled by firmly installed and mobile monitors which give alarm when given limits are exceeded. Working on systems containing tritium is to be performed with special protection measures, so that the personnel cannot get in touch with tritium containing atmosphere. In the reactor laboratory, where unsealed radioactive substances are handled, the workplaces can be surveyed by monitoring the air. To avoid the spreading of contamination out of the controlled areas, the exits of these areas are equipped by hand-feet monitors and whole-person monitors. By the above mentioned survey instrumentation with appropriate alarm settings, when limits are surpassed, and with additional organisational measures, especially control and limitation of access, establishment of zones of radioprotection the protection of staff, students and guest scientists is ensured. MONITORING THE FACILITIES The installations of radiation and activity control have been planned in order to keep under surveillance the limits of the radiation protection ordinance for the staff and the public. These installations have the following tasks: • Control of the activity flow in the systems of the facility and the due function of the activity barriers enclosing the radioactive substances. • Control of the exposition of the personnel working in the facility and determination of direct radiation, contamination and airborne concentration inside the facility including the control of objects, working clothes and other surfaces under contamination. • Control of the emission and preparation of the balance-sheet of radioactive effluents via the stack and the waste water. • Control of the exposition of the environment by direct measurements and sampling in the surroundings and by calculating the impact of the emission of radioactive effluents on the environment. The planned installations of radiation and activity control consist of the following subsystems: 1. Control of the different systems inside the facility: About 10 monitors control the activity concentration of: P-6a-310 the coolant in different places: primary coolant cleaning system, secondary coolant system, the warm layer; the exhaust air from the filtered system and the hot cell. 2. Dose rate monitoring: About 18 fixed and about 20 mobile monitors survey the dose rate in different locations.The monitors installed respectively in the experimental hall, the reactor hall and the neutron guide hall are presented in table 1, figures 2 and 3. 3. Control of contamination: About 3 personal monitors, 4 hand-feet monitors and about 13 mobile contamination monitors as well as smear-test monitors and tritium contamination monitors are used. 4. Control of airborne concentration in room air: About 2 monitors for gaseous and 2 for airborne aerosol activity as well as 2 monitors for tritium are installed, mobile monitors are also at hand. The activity of argon 41 in the neutron guide hall is determined regularly by gammaspectroscopy of a compressed air sample. 5. Emission control is presented in table 2 and figure 4: About 3 monitors and 4 sample-taking devices for gaseous and airborne continuous emission control are installed, one monitor for the control of the liquid activities has been provided. 6. Laboratory instrumentation: Different laboratory measuring equipment including several liquid scintillation counters, gamma spectroscopy, alpha and beta monitors, smear-sample monitors, tritium monitors in two different laboratories as well in some other locations on the campus. 7. Control of the experimental installations: Different monitors control the exhaust of the cold neutron source, the pneumatic tubes and the hot cell. The dose rate inside the hot cell, at the unloading stations of the pneumatic tubes and of the irridiation stations are measured continuously. 8. Accident monitoring is presented in table 3, figures 3 and 4: 2 dose rate monitors and 2 monitors and 2 sample taking devices for gaseous and airborne continuous emission control are installed. 9. Immission control: Immission control is performed according to the