JPS59109897A - Method of removing crud in reactor primary coolant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for removing crud contained in the primary cooling water of a nuclear reactor. Refers to muddy or colloidal particles such as iron oxide, cobalt oxide TL, etc., which are formed by the oxidation of Fe injected into the melt and mainly have holes α-Fe203.

In the cooling water of a nuclear reactor, α-F e is generated during the circulation process.
It is believed that the accumulation of crud mainly composed of 205 and 205 will increase the exposure dose to humans during the early inspection of the reactor, leading to a number of failures. Therefore, it is necessary to provide a means to remove the crud. is necessary. This crud removal method is
The cladding itself requires 74 ions, but it is generally adsorbed by ion-exchange resin when exposed to it, but the adsorption efficiency is not sufficient and the cost is high. It is also a heavy financial burden.

This invention facilitates the removal of crud in the cooling water of nuclear reactors by using a tl adsorbent that has higher adsorption efficiency and is significantly cheaper than the commonly used ion exchange resins. The objective is to provide a method that can be removed economically.

The adsorbent used in the method of this invention consists of a finely ground powder of the thin brown skins of onions or peanuts. Traditionally, this powder.

Contains glycosides such as cosmoidin represented by n, and acts as a cation exchanger as a whole,
It is known that some metals are often captured by ion exchange. This time, by flowing the primary cooling water of the nuclear reactor through an adsorption tower filled with a portion of these naturally occurring plant fractions as an adsorbent, we have effectively removed the crud contained in (1n). It was discovered for the first time by Nagisa, the inventor of the present invention, that f'l is effective in adsorption and removal of f'l.

Onion and peanut skins can be crushed and used, but there are inconveniences such as rotting during storage or use, and pigments eluting into the cooling water and causing color! [7
Where −8C= is placed, a purification treatment is performed to remove the fraction useful for adsorption. UU,.

[Purification treatment]

To prepare 1 fc onion, add 5 parts of 39% formaldehyde and 20 parts of 2N sulfuric acid to 1 part of ground peanut skin powder, and heat at about 50°C for 2 hours (7JI). Next (= This mixed axillary is filtered, and the solid matter remaining on the filter is washed with distilled water at a pH of 4 to 5.
Dry in an oven at 0°C.

It is recognized that this process causes almost no increase in the zero-placement ability.

Removal of crud using this adsorbent is easy (as with general ion exchange resins) by filling an appropriate column with the adsorbent and flowing a cooling tank through the column. Yes, the adsorption conditions are particularly limited.
However, the lower the pH, the higher the N absorption rate (p excess rate), so it is desirable to ladle under conditions of pH 7 or lower.

Example: Cylindrical collar 2 (inner volume 3,
140) was filled with 0.5 F of onion skin powder subjected to the above-mentioned Japanese processing, and distilled water (2α-F 8203
A sample made by dispersing powder (particle size approximately 0.1/1 m) was streamed*15 cc/wiring (linear velocity 0.32σ/degree,
After passing through the column at a void velocity of 0.51η), α-Fe20. The concentration of f is measured to determine the filtration rate, and its concretion is shown in the following first coat C:. In addition, in the example, it can be seen that the filtration rate improves as the water flow rate increases.

Table 1 (b) Water with a pH of 3.2 was flowed in advance to completely bring the inside of the column to pH 3.2 (pH 3.2) before the assay was run.

COMPARATIVE EXAMPLE A conventional cation exchange resin was placed in the same column as that used in the above example with a bed height of 9 cm (Example 2).
, 25 times) and using the same test method as in the example but omitting the filtration test, Table 2 shows the method of assembly obtained.

In the previous example, onion skin was shown, but the same effect was obtained with peanut skin.

According to the present invention, 1 is compared with the adsorption by ion exchange resin, which is conventionally used, and < i
It is clear that good filtration properties are exhibited even under high pH conditions. Moreover, since the adsorbent used in this invention is made from peanut peels, which are usually waste boiled, it is also extremely economical.

Furthermore, it has a much smaller volume than regular ion exchange resins.
(Tetemi, and since it is made of natural plant ingredients,
During long-term storage as radioactive waste (= decayed by R-resistant bacteria), it is not only possible to reduce the volume by 2 times, but also to undergo oxidative combustion treatment (decompose into CO2 and H2).
It is also easy to set it to O.

(Unlike ordinary ion exchange resins, which are difficult to decompose due to the chemical C bistable t'i, which has been used for 1 reason, conventional Jimira 217
'J1. /'1 There are six major advantages in that it is possible to significantly reduce the volume of waste.

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Claims (1)

[Claims] An adsorbent made of powder obtained by pulverizing onion or peanut skin to an appropriate tJ particle size (= an adsorbent that adsorbs and removes the -Fn-containing crud contained in the 1g cooling water by bringing it into contact with the 1g cooling water of a nuclear reactor. Clarard removal force method in primary cooling water of nuclear reactor.