New, unconventional methods developed at the Russian Science Center Kurchatov Institute for evaluating the state of spent VVR fuel assemblies from submarines are described. They were used in ...combination with other methods during inspections of spent fuel assemblies held in TK-6 and -11 containers at the point of storage of spent nuclear fuel and radioactive wastes in the town of Gremikha in Murmansk Oblast.
The radiation conditions in the dry-storage block for spent nuclear fuel BSKh-3A was characterized by a high dose rate and allowed only brief admission of workers. The plan to normalize the radiation ...conditions included repeat replacement of workers, whose individual dose limit has been exhausted, and on the whole did not conform to the principle of protection optimization. Analysis of the design and radiation state of BSKh-3A has shown that possibilities for reducing the worker dose do exist. At the stages of current planning and actual performance of the work, it was possible to make changes in the technology used in the work, reduce labor costs, and add and optimize additional protection. As a result, the work was performed in accordance with the radiation safety norms and regulations, worker replacement was not required, and the collective dose was reduced more than 20-fold compared with the nominal level.
As part of the work on eliminating the nuclear legacy temporary storage facilities for high-level solid wastes were opened, radiometric inspection of the wastes was performed, wastes were sorted, ...control rods of ship reactors were identified in the wastes and removed, and spectrometric determination of the induced activity in each rod was made. Forty-four rods with activity totaling 1.35·10
13
Bq were packaged and shipped to a long-term storage site. The activity distribution was determined from samples and will be taken into account in planning subsequent work on the handling of such wastes and picking the most appropriate type of packaging. The work was performed using remote-control machines in compliance with the standards and regulations for the radiation safety of personnel.
An information-analytical system for solving various problems facing developers and implementing agencies at all stages of work has been developed at Russian Science Center Kurchatov Institute as ...part of a project for ecological rehabilitation of a temporary storage site located in the village of Gremikha for nuclear fuel and radioactive wastes. The information-analytical system accumulates all information on the project: technical characteristics of the objects, cartographic information, documentation, and information on the participants of the project, technologies, and equipment. The centralized storage of the initial data and the data obtained from examinations makes its use effective for all participants of the project. Analysis of the stored information and the formation of structured sets of data are necessary for planning further work on the project and choosing concrete design solutions, exchanging information between participants in the work, and providing information to state organs and the public.
The remotely controlled replacement of the concrete covering of the spent
fuel dry storage unit 3A with a new iron horizontal biological shielding was
carried out during works aimed at the ...improvement of the radiological
environment at the NWC ?SevRAO? - Branch of FSUE ?RosRAO?, Andreeva Bay,
Murmansk Region. Video control systems, a BROKK robotic manipulator, HIAB
manipulator crane, gamma detectors of the ASCRO radiation monitoring system,
and a CARTOGAM gamma camera were employed. A CARTOGAM gamma camera was used
in all stages of the work involving high radiation levels for the remote
location of the most dangerous gamma radiation sources and the evaluation of
their dose rates. Gamma detectors of the ASCRO radiation monitoring system
were located at several spots of the dry storage unit 3A in order to control
the radiation situation. The use of the ASCRO and CARTOGAM has allowed us to
avoid unauthorized exposure of the staff involved in the operations at the
dry storage unit 3A site.
U cilju unapredjenja radioloske sredine izvrsena je daljinski upravljana
zamena betonskog prekrivaca skladisne jedinice 3A isluzenog goriva novom,
gvozdenom i horizontalnom, bioloskom zastitom. Skladiste se nalazi u Zalivu
Andrejeva, u Murmanskoj oblasti. Korisceni su video sistemi, BROKK robotski
manipulator, HIAB kran, gama detektori iz ASCRO sistema za monitoring
zracenja i CARTOGAM gama kamera. CARTOGAM gama kamera koriscena je u svim
fazama posla, ukljucujuci visoke nivoe zracenja, za daljinsko lociranje
najopasnijih izvora gama zracenja i procenu njihovih jacina doza. ASCRO gama
detektori bili su postavljeni na nekoliko pozicija oko skladisne jedinice 3A
za nadgledanje nivoa radijacije. Korisceni ASCRO detektori i CARTOGAM kamare
omogucili su da se izbegne neovlasceno izlaganje zracenju osoblja koje je
ucestvovalo u radu.
One of the most important problems arising in the comprehensive salvaging of nuclear submarines and the ecological rehabilitation of previous shore-based technical bases is the handling of the spent ...nuclear fuel. For the temporary storage site in Gremikha this is the preparation and removal of about 800 fuel assemblies and eight spent parts removed from Alpha class boats. The unsatisfactory state of the infrastructure and the sanitary-hygienic support on the object made it impossible remove the spent fuel immediately. Several years of work were needed to remove at the end of 2008, following the standard scheme, the first batch of 294 fuel assemblies for reprocessing at the Industrial Association Mayak. This was accomplished with the active and financial support of the French Atomic Energy Commission, the European Bank for Reconstruction and Development, and the European Commission (TACIS).
The search of the main gamma-radiation sources at the site of the temporary storage of solid radioactive wastes was carried out. The relative absorbed dose rates were measured for some of the ...gamma-sources before and after the rehabilitation procedures. The effectiveness of the rehabilitation procedures in the years 2006-2007 was evaluated qualitatively and quantitatively. The decrease of radiation background at the site of the temporary storage of the solid radioactive wastes after the rehabilitation procedures allowed localizing the new gamma-source.
Prikazana je potraga za glavnim izvorima gama zracenja na prostoru privremenog odlagalista cvrstog radioaktivnog otpada. Za neke gama izvore, pre i posle postupka rehabilitacije, izmerene su relativne jacine apsorbovanih doza. Uspesnost postupka rehabilitacije u periodu 2006-2007. godina procenjena je kvalitativno i kvantitativno. Slabljenje osnovnog nivoa zracenja na prostoru privremenog odlagalista cvrstog radioaktivnog otpada, omogucilo je lokalizaciju novih gama izvora po sprovedenom obnavljanju.
Places of location of some γ-ray sources on the site for temporary storage of solid radioactive wastes of SevRAO OF-2 Federal State Unitary Enterprise (Gremikha settlement, Murmansk oblast, Russia) ...were determined using a procedure for remote determination of radiation source coordinates with a Cartogam γ-imaging system. The γ-ray spectra from these radiation sources were recorded using the remote procedure with an ISOCS spectrometric complex. In particular, the isotope composition of γ-active containers Bet8, TK113, L18, and L20 was determined. The main technogenic γ-radiation from these objects is associated with the decay of
137
Cs and, to a lesser extent, with the decay of
60
Co,
152
Eu, and
154
Eu. For the Bet8 container, its activity content was estimated (∼10
14
Bq). The dependence of the specific activity of the soil surface layer in the guard zone in front of the waste storage site on the distance from the site was determined with a 7 m step. The specific activity considerably decreases with an increase in the distance from the site (from 15–28 kBq kg
−1
at a distance of 3 m to 1–2.8 kBq kg
−1
at a distance of 10–24 m).
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