RU2134459C1 - Method for disposal of solid radioactive wastes in permafrost regions - Google Patents

Abstract

FIELD: handling and disposal of contaminated soil and bottoms of water reservoirs in Arctic regions. SUBSTANCE: solid radioactive wastes charged with isotopes of plutonium and radionuclides which escape during subsurface nuclear explosions on difficult-to-get-at and little-inhabited areas of Arctic region are gathered from contaminated territory and disposed to surface burial hills. Solid radioactive wastes are placed in layer-by- layer manner and each layer is rammed, rinsed with water, and frozen by natural cold in winter. EFFECT: provision for localizing radionuclides for long time. 2 cl, 1 dwg

Description

 The invention relates to the field of treatment and disposal of solid radioactive waste (TPOA): soil, soil, vegetation, bottom sediments of streams contaminated with radionuclides and plutonium isotopes emitted from accidents from wells during the production of underground nuclear explosions (UNE) for peaceful purposes in the distribution zone permafrost (ZRMM), in remote inaccessible areas of the North.

 A known method of disposal of solid radioactive waste [1] in the surface burial sites of the bunker type, erected on a trained foundation of cast concrete. TPAO are placed inside the hopper in special containers. After filling the hopper with containers, the entire interior space is filled with special concrete solutions. The hopper is tightly closed and carefully sealed. Then, over the bunker, with the help of bulldozers, a mound is built in layers in the following sequence from the bottom up: gravel, a sand cushion, a waterproof bituminous geomembrane is built on top; sand drain; a layer of gravel; soil layer. The total height of the mound is 10 meters. After filling and tamping the mound, it is covered with a layer of soil, which is planted with perennial grasses and shrubs.

 The disposal method (according to experts' forecasts) should ensure the complete isolation of solid waste for 300 years.

 The main disadvantages of the above method of disposal of solid waste are: the need to separate the solid waste by the degree of activity, which cannot be done after the accident; the need for concentration of solid waste, which is also extremely difficult to do after an accident and the need for special stationary installations; Mandatory packing of solid waste in stainless steel containers that must be imported; great difficulties in erecting a bunker in an uninhabited area and considerable costs.

 The disposal method and construction of the repository do not guarantee the complete isolation (≈ 300 years) of the TPOA, while the half-life of plutonium isotopes lasts tens of thousands of years and, therefore, after the storage period, the TPO containing plutonium isotopes must be reburied.

 In order to reduce the time for disposal of solid radioactive waste, to localize the migration of radionuclides, to reduce the cost of construction of a repository, a method for their disposal is proposed in ZMM, which consists in constructing burial mounds of simplified design directly in the infected area, using local materials, natural resources characteristic of ZMM, and developed technologies industries of the North - mining, hydraulic engineering.

 Closest to the claimed method is a method for the disposal of solid radioactive waste in the permafrost zone, described in the USSR author's certificate 1829721, 1996, G 21 F 9/24.

 The claimed invention is aimed at solving the problems of localization of APNW radionuclides and, as a consequence, ensuring the safety of the population and the environment of the northern regions of the country from the most dangerous emergency factor - long-lived radionuclides and plutonium isotopes thrown out during accidents from wells during underground nuclear explosions.

The required technical result in the implementation of the invention is expected to be obtained with the maximum use of the climate and natural resources of the North:
a) the presence of continuous permafrost;
b) the wide distribution of a natural natural preservative - ice (in all possible forms);
c) sharply continental climate with harsh winters;
d) small capacity (1.5 - 2.0 m) of seasonal thawing of soil (soil) in the summer period;
d) negative heat balance - the amount of heat received by the repository in summer is lower than its outflow in the cold season.

 The inventive method for the disposal of solid radioactive waste (TPO) consists in laying collected areas from soil contaminated with radionuclides (soil, vegetation, bottom sediments of streams, etc.) on a specially prepared site in layers in winter with each layer spilling with water until completely saturated and freezing naturally the cold. The result is an ice-rock structure of a mound type - a burial ground in which TPOs are compounded with ice, which prevents the migration of radionuclides outside the contaminated area.

 After completion of the installation of the TRAO, the entire surface of the mound is covered with an ice shell, which acts as a barrier and accumulator of cold; a layer of loam is applied on top, then a heat-insulating layer of local materials, which prevents thawing of the burial ground in the summer. A layer of soil and soil is poured on top, which is planted with perennial grasses and shrubs to prevent erosion.

 The proposed method allows (in comparison with the analogue [1]) to do without the construction of a bunker, concentrate solid waste, packing in containers, compounding, which can significantly reduce costs.

FIG. 1 Combined method for the disposal of solid radioactive waste (solid waste) in burial mounds in the permafrost propagation zone
1 - the base of the burial ground (soil not contaminated with radionuclides);
2 - TPAO cemented by ice;
3 - ice shell (barrier);
4 - ice-cemented loam;
5 - thermal insulation layer;
6 - soil layer;
7 - soil layer;
8 - shrub, perennial grasses.

The work is carried out in winter with the onset of a stable negative air temperature (t _av.day. ≤ - 10 ^o C) directly on the territory contaminated with radionuclides using equipment used in open cast mining and hydraulic engineering (bulldozers, scrapers, loaders, dump trucks) .

 The collected solid radioactive waste (contaminated soil, soil, vegetation) from the contaminated area is transported to the prepared elevated base (1) of FIG. 1, leveled and compacted with a bulldozer; layer thickness ≈ 20 - 30 cm (2). The laid layer is abundantly watered with water from a watering machine, after which it is frozen with natural cold. If necessary, spill with water and subsequent freezing are repeated. After this, the second layer is laid out and frozen, and so on, until all radioactive waste is completely laid out in the burial mound in accordance with the natural analogue - the heaving hill, which plays the role of a barrier and an additional cold accumulator. A layer of loam (4) with a spill of water and freezing is laid on top of the ice shell. Then, a heat-insulating layer of local materials (moss, peat, sawdust, slag) of the calculated thickness (5) is laid, which ensures a stable negative temperature of the laid frozen TPO during the summer period, the thickness of which is inversely dependent on the capacity of the cold accumulator. On top of the heat-insulating layer, successively poured: a soil layer (6), a soil layer with tamping without spillage with water (7).

 The radioactive waste repository should represent a mound in shape, and with a large number of radioactive waste - to the prism of a trapezoidal cross section, elongated by a long axis from north to south. The overall dimensions of the repository are determined by the amount of radioactive waste and the technical capabilities of the mechanisms used during installation.

All work must be completed in the winter (t _{cf. day} ≤ - 10 ^o C). In summer, the surface of the repository should be planted with perennials with herbs and shrubs to protect against erosion (8).

 The erected burial ground will represent an artificial heaving hillock, being a natural part of the northern landscape, and will not require special attention, except for periodically cutting down coniferous shoots to avoid fire.

 Ice-cemented TPOs located in the repository, reliably protected from adverse factors - thawing and penetration of fluids (air, water), deprived of the ability to migrate, will not be described for biota; being in a burial ground in a low concentrated form, they will not produce heat and do not require additional cooling in the summer with engine (artificial) cold.

The main advantages of the proposed method (technology):
- high mechanization of all types of work;
- the use of mass-produced (non-special) equipment for all types of work, widely used in the national economy;
- Combining operations on compounding, stacking and disposal of radioactive waste;
- insignificant expenses for all types of work due to the use of the same natural substance - water (ice) as a compounding material and a barrier material.

- use of natural cold to ensure negative year-round temperature inside the RW repository;
- use of local (natural) materials and waste for thermal insulation of the burial ground.

Literature:
1. Stocraqe des deehets radioaetiff un abei a'tontes eprenves (Surehamp Ar 11 Chant. Er. 1992 - 251.p. 28-29 - Fr.

 2. Karpov EG Underground ice of the Yenisei North. - Novosibirsk: 1986, 123 s.

Claims (2)

 1. A method for the disposal of solid radioactive waste (TPOA) in the permafrost zone, characterized in that TPOA is layered in layers on a prepared site, each layer is leveled and compacted, watered with water and frozen with natural cold until all radioactive waste is laid out, then the entire surface is covered with ice with a carapace, a layer of loam is applied over it with its gradual freezing, after which an insulating layer of local materials is laid, and a layer of soil and soil is poured on top of it without frosting, and this burial place is formed as a mound, and when a large number SRW - a lying prism with a trapezoidal section the long axis of elongated from north to south.  2. The method according to claim 1, characterized in that peat, moss, sawdust and slag are used as local thermal insulation materials.