CS217141B1 - A method of decontaminating laundry and clothing - Google Patents

Abstract

The essence of the invention is that 1 kg of contaminated clothing or laundry is soaked for 30 to 60 minutes in 4 liters of water at 30 °C with the addition of Alfa detergent in the amount of 0.8 to 1.2 g per 1 liter of water and technical grade ethylenediaminetetraacetic acid disodium salt (Syntron B) in the amount of 0.4 to 0.6 g per 1 liter of water, after which it is rinsed in six to seven times the volume of water at 25 to 30 °C for 4 to 6 minutes, then washed in 4 liters of water at 95 °C for 15 to 25 minutes with the addition of Zenit detergent in the amount of 2.5 to 3.5 g per 1 liter of bath for lightly contaminated and lightly soiled clothing or laundry, or 4 to 5 g per 1 liter for heavily contaminated and heavily soiled clothing. or laundry and 0.4 to 0.6 g per 1 l of water of disodium salt of ethylenediaminetetraacetic acid - technical grade (Syntron B) and 0.4 to 0.6 g per 1 l of water of pure sodium hexametaphosphate, then rinse 3 to 5 times for 2 to 7 minutes, with the volume of rinse water for the washing bath increasing gradually in each STEP by 20 to 30% and its temperature decreasing in each step by 15 to 20 °C.

Description

The invention relates to a method of decontamination of laundry and clothing contaminated with radioactive substances, e.g. of workers at nuclear power plants.

Currently, the laundry and work clothes of nuclear power plant workers are washed according to separate procedures established by the operating rules of the special laundry, according to which the washing process begins with soaking in a strongly alkaline environment with subsequent spinning and double intermediate rinsing. Then the actual washing takes place in detergent solutions. Then the laundry or clothes are rinsed first in clean water and later in water with the addition of a complexing agent, while the temperature of the rinsing water is gradually reduced. Rinsing - depending on the type of clothing and laundry, is usually carried out five times.

The disadvantage of the current state of the technology used is the low decontamination efficiency, which not only negatively affects labor productivity, but also leads to direct economic losses, because laundry and clothing are discarded as radioactive waste due to insufficiently effective decontamination. The low decontamination efficiency is caused by several incorrect steps in the washing process. These are mainly j

- soaking in a strongly alkaline environment, which causes the formation of colloidal forms of radionuclides, which are slightly but irreversibly adsorbed onto the surface of decontaminated materials, and in addition, in an alkaline environment, conditions are not created for effective competition for the adsorption of ionic forms of radionuclides; on the contrary, their adsorption increases at high pH, because the ion-transfer capacity of weak cations increases, which are the decontaminated fabrics due to their chemical nature.

- late addition of the complexing agent, only after the fourth to seventh operation, can no longer positively affect the decontamination efficiency

- selection of detergents, which are not optimal in terms of washing properties and, moreover, they cause a large amount of foam during chemical treatment of water, which on the one hand limits the activity of anodic dissolution of iron and on the other hand causes the formation of fine bulky flakes that float. Flotation negatively affects the function of the clarifier and also causes overloading of the filter layer

- a high concentration of silicates and phosphates causes the formation of a significant amount of bulky sludge that sediments poorly.

The disadvantages of the current state of the process are eliminated by the method of decontamination of clothing and linen according to the invention, the essence of which is that 1 kg of contaminated clothing or linen is soaked for 30 to 60 minutes in 4 liters of water at 30 °C with the addition of a detergent composition containing anionic detergents and active detergents, soap with reduced foaming, sodium perborate, activating additives of the condensed phosphate type, protective colloid, alkaline silicates and an optical brightener, in addition, the Zenit composition in an amount of 0.8 to 1.2 g per 1 liter of water and disodium salt of ethylenediaminetetraacetic acid - technical in an amount of 0.4 to 0.6 g per 1 liter of water, after which it is rinsed in six to seven times the volume of water at 25 to 30 °C for 4 to 6 minutes, then washed in 4 liters of water at 95 °C for 15 to 25 minutes with the addition of another detergent containing anionic detergents and active detergents in combination with soap with reduced foaming, activating additives of the condensed phosphate type, further protective colloid, alkaline silicates and optical brightener, in the next agent Alfa in the amount of 2.5 to 3.5 g per 1 l of bath for lightly contaminated and lightly soiled clothes or linen, or 4 to 5 g per 1 l of bath for heavily contaminated and heavily soiled clothes or linen and 0.4 to 0.6 g per 1 l of water of technical disodium salt of ethylenediaminetetraacetic acid and 0.4 to 0.6 g per 1 l of water of pure sodium hexametaphosphate, then 3 to

It rinses 5 times for 2 to 7 minutes, with the volume of rinsing water increasing gradually by 20 to 30% in each step compared to washing bath D and its temperature decreasing by 15 to 20 °C in each step.

The advantage of the invention is higher labor productivity, since a single technological process consisting of soaking and washing achieves a reduction in the original activity of clothing and linen below permissible values. Another advantage is that the amount of so-called non-decontaminateable clothing and linen has been reduced to a minimum, practically only to that clothing and linen which, in addition to contamination, has also been in contact with fats, e.g. oils, or lubricants. There is also a saving in costs for

217 141 waste· Another advantage is that the detergents and other substances used for washing and soaking do not interfere with the course of decontamination of wastewater from a special laundry. The washing process according to the invention reduces the decontamination time practically by half.

The invention will be explained in more detail and described on two examples of possible embodiments of the invention using Table 1.

Example 1

In a specific example of implementation, 31 kg of heavily contaminated and heavily soiled laundry with a surface activity higher than 300 pCi.cm was decontaminated. A washing machine of special design for the laundry of the Nuclear Power Plant was used.

The linen was decontaminated in the manner specified in Table 1. After decontamination, 100% of cotton and 66% of synthetic polypropylene-based fabrics were decontaminated below the permissible contamination limit. Only in the case of overalls made of synthetic polypropylene-based fabrics contaminated with so-called operational contaminants and simultaneously with fatty oils, fats, or lubricants, only 14% of the fabrics complied with the specified parameters, namely:

for workwear a/ alpha active nuclides b/ beta active nuclides, for the reasons that the specified type of fabric chemically reacts with fats, oils and lubricants, which change their chemical structure.

Example 2

In a specific embodiment, 6.25 kg of lightly contaminated and lightly soiled clothing were decontaminated. The washing machine as in Example 1 was used. The clothing was decontaminated in the manner shown in Table 1.

After decontamination, 100% of the fabrics were decontaminated satisfactorily according to the specified parameters as in Example 1.

- very toxic 10 pCi/cm ² ( 0.37 Bq/cm ² )

- others 10© pCi/cra? ( 3.7 Bq/cm ² )

- 100 pCi/cm ^{2 ( 3} « ^{7 Bq/cm} ) ·

TABLE 1

Operation Filling ( 1 ) Temperature ( * c ) Time (min) Alpha Dose Syntron substances (g) B Zenit HKFNa ========== ======== ========== : =====: ======= ========== = : =====: Soaking 120 30 60 120 60 that Rinse 210 30 5 - - a a - Laundry 120 95 20 that 60 ⁺ 540/360 ^{and ;} 60 Rinse 150 80 5 - - - - Rinse 170 60 3 - that that - Rinse 150 40 3 ab - - - Rinse 240 student 3 - that that

Note: Syntron Β·« disodium salt of styrene diaminetetraacetic acid technical HMFNa and pure sodium hexametaphosphate

Cool - cold water + « detergent addition for heavily contaminated and heavily soiled laundry or clothes

217 141 x = detergent addition for lightly contaminated and lightly soiled laundry or clothing

The limit between + and x is taken from the personal legal provisions, which state 100 pCi » cm ( 3.7 Bq . cm ¹² ) .

Claims (1)

Method for decontamination of laundry and clothing contaminated with radioactive substances, characterized in that 1 kg of contaminated clothing or laundry is soaked for 30 to 60 minutes in 4 liters of 30 ° C warm water and by adding a laundry detergent composition containing anionic detergents and active detergents in combination with soap with reduced foaming and condensation phosphate activating additives, protective colloid, alkaline silicate and optical brightening agent in the amount of 0.8 to 1.2 g per 1 of water and disodium stylenediaminetetraacetic acid - technical in the amount of 0.4 to 0.6 g per 1 l of water, then rinse in 6 to 7 times 25 to 30 ° C warm water for 4 to 6 minutes, then wash in 4 liters 95 ° C warm water for 15 to 25 minutes with the addition of a laundry detergent containing anionic detergents and active detergents, foaming soap, sodium perborate, activating detergents condensate phosphate additives, protective colloid, alkaline silicates and optical brightener in an amount of 2.5 to 3.5 g per 1 bath for lightly contaminated and lightly soiled clothes or laundry, or 4 to 5 g per 1 bath for heavily contaminated and heavily soiled clothes or laundry and 0.4 to 0.6 g per l of water of disodium ethylenediaminetetraacetic acid - technical and 0.4 to 0.6 g per l of sodium hexametaphosphate pure, then rinsed 3-5 times for a period of time 2 to 7 minutes, wherein the inhalation volume of the water is increased by 20 to 30% successively in each step against the wash liquor and its temperature decreases by 15 to 20 ° C in each step. Printed by Moravian Printing Works,