Radionuclide inventory

Results from the Group estimate, when compared to those from SIAE, showed the following  

The following sections detail the methods used to estimate the radionuclide inventories of the nuclear submarines and icebreaker. The results are given in Tables III to XVI. 

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The radionuclide content of the aqueous phase will be a more sensitive indicator of change than the sediment since only a small proportion of the radionuclide inventory is present in solution. Over a three day period, the control batch (Figure 1) showed a 20%... 

J. Jowett, Customer Guidance on the Requirements for Waste Package Radionuclide Inventories, NIREX, (SERCO), Report No. A/R/PSEG/04441, Draft 3, December 2001. 

Of particular relevance is the inherent hazard represented by the radioactive inventory of the waste and is the summed product of the activity (Bq) of each radionuclide present and its corresponding Specific Instantaneous Toxic Potential (SITP). This can be adjusted for decay for longer timescales and it is usual to employ the full radionuclide inventory for waste streams as sampled and quantified by Magnox Electric Ltd and reported in the U.K. Radioactive Waste Inventory. ... 

Improvements to the quality of the radionuclide inventory from developments in sampling, detection and analysis also serves to improve the RHP assessment. 

Actinides in the environment can be classified into two groups (i) the uranium and thorium series of radionuclides in the natural environment and (ii) neptunium, plutonium, americium and curium which are formed in a nuclear reactor during the neutron bombardment of uranium through a series of neutron capture and radioactive decay reactions. Transuranics thus produced have been spread widely in the atmosphere, geosphere and aquatic environment on the earth, as a result of nuclear bomb tests in the atmosphere, and accidental release from nuclear facilities (Sakanoue, 1987). Most of these radionuclide inventories have deposited in the northern hemisphere following the tests conducted by the United States and the Soviet Union. 

On 7 April 1989, a fire broke out in the stem section of the Komsomolets nuclear submarine. The submarine sank to a depth of 1685 m at 73°43T6"N, 13°15 52"E, near the south-west of Bear Island. The site is about 300 nautical miles from the Norwegian coast. The wreck contains one nuclear reactor and two nuclear warheads, one of which was fractured. The radionuclide inventory includes 1.5 PBq Sr, 2 PBq Cs, about 16 TBq " Pu in the two warheads and 5 TBq of actinides in the reactor s core. During June/July 1994, an international expedition to the Komsomolets site at the request of the Russian Federation was organised. The objectives of the scientific cmise on board the R/V Mstislav Keldysh were to close nine door holes, including torpedo tubes, by capping them with titanium metal cover caps, and to sample and monitor for ambient radioactivity. A series of 280-600 1 sea-water samples collected in profile, a suite of surface sediments and cores and various biota samples were returned to lAEA-MEL for analysis. The results showed that a very limited leakage of caesium and tritium had occurred from the submarine. 

Caesium is said to behave conservatively that is, the bulk of the radionuclide inventory is associated with the water phase and so transport processes are dominated by the bulk movement of sea water. Plutonium and americium, on the other hand, behave non-conservatively the bulk of their inventory is associated with sediments and the transport processes affecting sediments are very important to their behaviour. The proportion of each nuclide present in the water column as suspended particulate is a simple function of value and suspended sediment load (Sholkovitz, 1983), as indicated in Table 8.2. Thus, for the full range of sediment loadings, water column inventories of Cs are dominated by... 

Edgington, D. N., J. Van Klump, . A. Robbins,Y. S. Kusner, V. D. Pampura I. V. Sandimirov, 1991. Sedimentation rates, residence times and radionuclide inventories in Lake Baikal from Cs and... 

FUNCTION Retain Radionuclides in Fuel This function refers to the Standard MHTGR safety design approach to design, fabricate, and operate the fuel so that normal operation releases are limited to the extent that only the radionuclide inventory within the fuel itself presents a potential challenge to meeting the lOCFRlOO doses. Thus, only the fuel conditions need be maintained for off-normal events to assure lOCFRlOO compliance. The three sub-functions described in the following paragraphs are those required to maintain the fuel within the required conditions. 

WE = Waste handling from storage in elevator pit to transfer and preparation for storage in room 109 WS109 = Waste storage in room 109 Radionuclide Inventory for Postulated Events... 

The Source Term Working Group was established to prepare a detailed inventory of and release rates for the radionuclides dumped at each Kara Sea disposal site. To this end, inventories were calculated for the spent nuclear fuel (SNF) and activated components at time of disposal and projected forward in time protective barriers, if any, were evaluated for their potential effect on radionuclide release and a number of model scenarios were developed to predict the potential release of the radionuclide inventory into the Kara Sea. 

The following sections detail what is currently known or estimated about the seven nuclear submarines and icebreaker with respect to the characteristics of their SGIs, their reactor operating histories, their radionuclide inventories, and their disposal operations. 

Table III presents a summary of the estimated total 1994 radionuclide inventories of fission products, activation products, and actinides in the marine reactors dumped in the Kara Sea [3, 7, 8,12].

TABLE III. ESTIMATED 1994 RADIONUCLIDE INVENTORIES OF FISSION PRODUCTS, ACTIVATION PRODUCTS, AND ACTINIDES IN THE MARINE REACTORS DUMPED IN THE KARA SEA [3, 7, 8, 12]... 

A prompt criticality with core disassembly in the far distant future would involve very little radioactivity compared to the present radionuclide inventory in these cores. By the year 2700, nearly all of the current fission product inventory in the cores would have decayed. Also, the amount of fission products produced in a prompt critical excursion is relatively small. For example, the amount of Cs generated in a 10" fission criticality excursion (about the same as the SL-1 accident in the USA) would be 0.044 GBq [31]. 

For the reactors and their associated SNF dumped in the Kara Sea, the isotopes making up the radionuclide inventory and their activities were calculated on the basis of the information on quantity, enrichment, and bumup of the nuclear fuel. These inventories were grouped into three categories fission products, activation products, and the actinides. 

Several hundred uranium dioxide fuel assemblies make up the core of a reactor. For a reactor with an output of 1,000 MWe, a typical core contains about 75 t of low-enrichment uranium ( 3.5% U). During the operating cycle of a nuclear reactor, several competing processes determine the final radionuclide inventory in the spent fuel. These processes are... 

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