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Method of decontaminating a metal surface in a nuclear power plant

A metal surface, nuclear power generation technology, applied in nuclear power generation, nuclear engineering, nuclear reactor monitoring, etc., can solve problems such as increased radioactivity and danger to operators

Active Publication Date: 2019-03-15
FRAMATOME ANP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Oxide flakes detached from metal surfaces can accumulate in low-flow areas of the coolant system, forming so-called "hot spots" with elevated activity that can only be removed from the coolant system with considerable additional effort, and is dangerous for operators

Method used

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  • Method of decontaminating a metal surface in a nuclear power plant
  • Method of decontaminating a metal surface in a nuclear power plant
  • Method of decontaminating a metal surface in a nuclear power plant

Examples

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Embodiment

[0111] Pair with about 500m 3 system volume and about 25,000m 2 A system-wide decontamination of the coolant loops of the nuclear plant's surface. The coolant system contains stainless steel and nickel alloy metal surfaces. Using Areva's HP-CORD TM A process comprising one or more treatment cycles performing an oxidation step using permanganic acid as an oxidant, a decontamination step using oxalic acid as a detergent and a purification step in which oxalic acid is decomposed by photocatalytic wet oxidation using UV light. The duration of the decontamination step is approximately 125 hours. The temperature of the decontamination solution was set at about 95°C.

[0112] Cycle 1 without oxidant dosing in the decontamination step

[0113] In the first treatment cycle, about 15 h after the start of the decontamination step, the oxygen content of the decontamination solution was found to decrease significantly, which can be recognized by the corrosion potential dropping below ...

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Abstract

The invention relates to a method of decontaminating a metal surface, wherein the metal surface is located on a component within a nuclear plant, in particular within the cooling system of a nuclear power plant, and is covered with a metal oxide layer containing radioactive substances, and wherein the method comprises a decontamination step in which a metal oxide layer pretreated in an oxidation step is contacted with an aqueous solution of an organic acid to dissolve the metal oxide layer, forming a decontamination solution containing the organic acid as well as metal ions and the radioactivesubstances, and wherein the decontamination solution is passed over an ion exchanger to immobilize the metal ions and the radioactive substances. An oxidant selected from the group consisting of oxygen, air, hydrogen peroxide and ozone is dosed into the decontamination solution to control the dissolution rate of the metal oxide layer. The method is particularly suitable for large-scale system decontamination and ensures high process stability.

Description

technical field [0001] The present invention relates to a method of decontaminating metal surfaces exposed to radioactive fluids during operation of a nuclear plant. In particular, the present invention relates to a method of decontaminating metal surfaces located within components of a nuclear plant, in particular in the coolant circuit of a nuclear reactor, wherein said metal surface is covered with a Metal oxide layer of radioactive material. Background technique [0002] A nuclear reactor includes a reactor vessel in which fuel elements containing nuclear fuel are located. A piping system forming a coolant circuit is connected to the reactor vessel, which coolant circuit is connected to at least one coolant pump and, in the case of a pressurized water reactor (PWR) or heavy water reactor, to a steam generator. [0003] Typically, the piping system of the coolant circuit consists of austenitic FeCrNi stainless steel. The heat exchanger surface of the steam generator ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21F9/00G21F9/28
CPCG21F9/004G21F9/28G21F9/12G21C17/0225Y02E30/30G21F9/30
Inventor 路易斯·森珀·贝尔达克里斯汀·托普夫
Owner FRAMATOME ANP