ICEM11 Final Program 9.7.11pm_ICEM07 Final Program ... - Events

Session 39 Abstracts
“ organizational measures concerning time of staffs or publics stay in the vicinity on conditionally released materials for
individual performed scenarios and nuclide vectors.
The article further describes VISIPLAN 3D ALARA calculation planning software tool, having been used for calculation of
staffs and publics external exposure for individual scenarios. Several other parallel papers proposed for ICEM 11 are presenting
selected details of the project.
A-3) UNCERTAINTY ANALYSIS OF ACTIVITY MEASUREMENT OF NEW MONITORING SYSTEM
FOR FREE-RELEASE FOR NPP A-1 DECOMMISSIONING, SLOVAKIA (wP-59244)
Alojz Slaninka, VUJE, a.s./ Slovak University of Technology in Bratislava; Ondrej Slávik, VUJE, a.s.;
Vladimir Necas, Slovak University of Technology (Slovakia)
Within 2nd stage of decommissioning project of NPP A-1 in Slovakia it is necessary to decontaminate, monitor and if possible
to free release large amounts of contaminated materials, mainly contaminated soil and concrete debris (thousands of tons). Their
contamination is caused by dominant 137Cs (33 years after shutdown) that emits 661.65 keV gamma ray that can be easily detected
by scintillation or semiconductor detectors. In this connection a new free release monitoring post with a large volume 600 L container
counting geometry was designed and developed. The monitoring system is based on a pair of electrically cooled semiconductor
HPGe detectors that are placed into a modifiable vertical or horizontal pair of lead collimators. The detectors are equipped
with a Canberra Packard gammaspectrometry chain including proper characterised HPGe detectors type GC 3020. The vertical
arrangement of the collimator ensures monitoring of materials in 200 l rotating drums. The horizontal one ensures monitoring of
the one side of a 600 l rectangular container. The monitoring system is integrated with an industrial scale for determination of massic
activities of measured materials and in addition by a rotating table in the case of 200 l drums monitoring. Full-energy peak detection
efficiency polynomial curves…
A-4) LASER REMOVAL OF CONTAMINANTS ON THE METAL SURFACE (wP-59343)
Hui Jun Won, Jei Kwon Moon, Sun Hee Jung, Chong Hun Jung,
Kune Woo Lee, Korea Atomic Energy Research Institute;
Byung -Sun Choi, Korea Atomic Energy Research Institute (Korea)
A Q-switched Nd:YAG laser with a 532 nm and 450 mJ/pulse was employed to study the decontamination characteristics of
Type 304 stainless steel specimens and aluminum specimens artificially contaminated with CsNO3 , Co(NH4 ) 2 (SO4 )2, Eu2O3 and
CeO2 , respectively. The relative atomic molar ratio of the contaminants on metal surface before and after laser irradiation was determined
by EPMA. The morphology of specimen surface was examined by SEM. The optimum number of laser shots and the laser
fluence for the system were determined. More than 98 % of CsNO3 , Co(NH4 ) 2 (SO4 )2, Eu2O3 on Type 304 stainless steel specimens
could be removed by the circular type laser beam within the 16 laser shots at 13.3 J/cm2 and 10 Hz. The removal of contaminants
on aluminum surface, however, was found to be more difficult by laser. Comparative study on the removal characteristics
between the circular type laser beam and the string type laser beam was also performed. The variation of laser removal performance
on the contaminants was investigated by changing the irradiation angle.
A-5) INFLUENCE OF THE CONDITIONAL RELEASE OF THE MATERIALS WITH VERY
LOW LEVEL OF RADIOACTIVITY ON THE ENVIRONMENT (wP -59132)
Slavka Prvakova, University of Economics in Bratislava; Adela Mrskova, DECOM, A. S.;
Jozef Pritrsky, DECOM (Slovakia)
Significant amount of solid materials (metals, non-metals, building structures) that could be contaminated or activated is produced
during operation and especially decommissioning of nuclear power plants. Considerable fraction of these materials has level
of radioactivity close to the radiological limits allowing its safe release into the environment thereby could be potentially recycled
within the special constructions, as for example tunnels, roads or bridges. If the requirements of legislation on the radiological limits
for handling such material and long term safety of the constructions are fulfilled, contaminated material can be released in the
form of recycled concrete, remelted steel, etc.
The paper presents implementation of the IAEA and EC recommendations into the form of detailed analytical approaches with
the aim to develop integrated scenarios and to analyse long-term influence of the conditional release of the material with very low
level of radioactivity on the environment. Further, an estimation of the key input parameters characteristic for the specific conditions
of Slovak case in order to fulfil the radiological limits according to the Slovak legislation is included. Analysed integrated scenarios
represent surface or underground civil construction with radionuclides released directly into the geosphere and transported
by a groundwater flow into the biosphere. The migration of radionuclides is modelled in the near-surface conditions with the advection
as a dominant transport mechanism. Computer code GoldSim is used to evaluate the long-term safety assessment of the conditionally
released material on the environment.
A-6) CONDITIONAL RELEASE OF STEEL FROM DECOMMISSIONING
IN A FORM OF REINFORCED CONCRETE (wP -59058)
Jozef Pritrsky, DECOM; Miroslav Brodnan, University of Zilina;
Vladimir Necas, Slovak University of Technology (Slovakia)
The paper deals with the conditional release of low-level radioactive steel from decommissioning in a form of reinforced concrete.
The main goal was to determine limits for radionuclides concentration and calculate the annual dose for a member of a critical
group of public, which should not exceed 0.01 mSv/year (according to IAEA Safety Guide RS-G-1.7). Corrosion is the principle
mechanism of radionuclides release in this case, therefore effort was devoted to assess the time-dependent rate of steel reinforcement
corrosion. It was assumed, that concrete is initially highly alkaline (with pH of 12 to 13) because of hydration products
such as calcium hydroxide, which keeps the steel surface passive and protected from corrosion. However, carbonic acid resulting
from carbon dioxide and water in the atmosphere can react with these products to produce calcium carbonate. This process is
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