Radiation-Hygienic Conceptions Analysis of Handling With Reactor Compartments of Being Utilised Nuclear-Powered Submarines. A. Ja. Blekher and V. V. Dovgusha, Research Institute of Industrial and Marine Medicine str. Yu. Gagarin, 67, 196143 St. Petersburg, Russia
Elaboration of conception for disjunction and utilisation of ships and vessels with nuclear-powered plants (NPP) removed out of exploitation includes the following main decision:
Two conceptions of handling with RC radioactive saturation have been discussed: the first one consists of the absence at present of enterprises with appropriate equipment for disjunction of RC with high-activity equipment and their long-term keeping is necessary for natural activity decay (during 50-80 years). After long-term keeping RC can be disintegrated without large dose expenditures and as a rule - without special remote and protective equipment. Thus for 70 years of keeping the rate of activated gamma-radiation sources will reduce in 1000 times on average.
The alternative conception provides for complete utilisation (remelting) of RC equipment and case. However RC disassembling immediately after ship's removal out of exploitation is connected with considerable dose loading, heightened risk of environmental radioactive contamination and necessity of using special equipment with remote control. Really, at being repaired nuclear-powered ships (NPS) the dose rate in reactor caisson was up to 400 mSv/h, near the reactor case 20-40 mSv/h, in steam generator caisson - 2 mSv/h. Thus, the present conception realisation is possible only after creation of specialised ship disintegrating enterprise, equipped with appropriate technology, that requires large-scale capital investments. Owing to the told the idea of disassembling of RC radioactive equipment before its maintenance did not obtain spreading neither in home nor in foreign practice and in spite of its attractiveness can be regarded only as perspective while keeping in containers ship's NPP equipment of NPS pressure hull and pressurising bulkheads upon its face planes has been realised both in our country and in USA. For normalisation of the radiation situation in conformity with sanitary requirements in the lower part of compartment, in the reactor's arrangement zone, separate areas of pressure hull (container) are covered by proper biological protection. The thickness and configuration in every concrete case can be determined by dosimetric inspection results.
The most reasonable and ecologically safe version in organising RC long-term storage of NPS removed out of exploitation is their arrangement in concrete trenches (holes), protected from atmospheric precipitation, or in polar climate conditions in permafrost or artificially frozen ground.
Go to:
Table of Contents of the 1997
SRA-Europe Conference
Program of the 1997 SRA-Europe Conference
RiskWorld Welcome Page
Tec-Com, Inc.