METHOD FOR REDUCING AMOUNT OF RADIOACTIVITY OF LIQUID

Abstract

According to the present invention, a method which dissolves hydrogen in a liquid that includes a radioactive substance is able to reduce the amount of radioactivity of the liquid. With respect to this method, the radioactive substance may include radioactive cesium, and hydrogen may be dissolved in the liquid by mixing a substance that contains a radioactive substance with a hydrogen water that contains 1.0 ppm or more of hydrogen.

Claims

1. A method for reducing an amount of radioactivity of a liquid including a radioactive substance, the method comprising: dissolving hydrogen in the liquid.

2. The method according to claim 1, wherein the hydrogen is dissolved in the liquid by mixing a substance that includes the radioactive substance with a hydrogen water that includes 1.0 ppm or more of hydrogen.

3. The method according to claim 1, wherein the radioactive substance includes radioactive cesium.

4. The method according to claim 2, wherein the radioactive substance includes radioactive cesium.

Description

DESCRIPTION OF THE EMBODIMENTS

[0011] Hereinafter, the effects of the present invention will be described by way of embodiments and comparative examples.

Embodiment

[0012] A cleaning liquid was sprayed onto a concrete slab to which a radioactive substance including radioactive cesium are attached, and the radioactive substance was dissolved in the cleaning liquid. The surface contamination density of the concrete slab was measured, and an average value of 5 measuring points was 3734 cpm. The cleaning liquid was water (hydrogen water) with dissolved hydrogen of about 1.3 ppm. The cleaning liquid was used in an amount of 120 L. Time required to spray the cleaning liquid was 1 hour.

[0013] The cleaning liquid after cleaning was recovered for 1 hour. The surface contamination density of the concrete slab from which the cleaning liquid was recovered was measured, and an average value of 5 measuring points was 2068 cpm. Therefore, the decontamination rate (unit: %, [surface contamination density before cleaningsurface contamination density after cleaning]/surface contamination density before cleaning100) was 45%.

[0014] After 22 hours from the completion of the recovery operation, the radioactivity of the recovered cleaning liquid was measured and found to be 32640 Bq (Becquerel). Since the recovery amount was 120 L, the radioactivity concentration of the recovered liquid was 272 Bq/L.

Comparative Example

[0015] As a cleaning liquid, 12 L of 3% hydrogen peroxide water was sprayed onto a concrete slab, and then 250 L of tap water flowed through and was recovered. Except that, cleaning was carried out in the same manner as in the embodiments. Regarding the surface contamination density of the concrete slab before spraying the cleaning liquid, an average value of 5 measuring points was 4218 cpm. Time required to spray the cleaning liquid was 1 hour, and recovery time was 1 hour.

[0016] The surface contamination density of the concrete slab from which the cleaning liquid and the tap water were recovered was measured, and an average value of 5 measuring points was 2406 cpm. Therefore, the decontamination rate was 43%.

[0017] After 24 hours from the completion of the recovery operation, the radioactivity of the recovered cleaning liquid was measured and found to be 225300 Bq. Since the recovery amount was 250 L, the radioactivity concentration of the recovered liquid was 901 Bq/L.

[0018] According to the above embodiments and comparative examples, it can be confirmed that the hydrogen water and the hydrogen peroxide water have the same ability to remove radioactive substances from the concrete slab, but regarding the recovered cleaning liquid, compared with the case of using the hydrogen peroxide water, the case of using the hydrogen water as the cleaning liquid significantly reduces the radioactivity concentration within a short time.