환원제염조건에서 가압경수로 구조재료의 틈부식 특성

국문 초록 (Abstract)

가압경수로의 일차계통 제염을 위해 개발된 HYBRID 제염제의 재료부식 특성을 틈부식 시험방법을 사용하여 수행하였다. 기존 제염제의 부식특성과 비교하기 위하여 상용 제염제인 OA, CITROX 제염제의 부식특성도 함께 평가하였다. 시험재료는 가압경수로의 일차계통의 주 재료인 Alloy 600과 304 SS을 대상으로 시험하였다. 틈부식 시험은 가혹조건의 부식시험으로써 내식성이 강한 원전 구조재료의 건전성을 짧은 시간에 잘 확인할 수 있었다. 시험결과 OA와 CITROX 제염제에서는crevice 시편 표면에 pitting과 IGA가 나타났으나 HYBRID 제염제에서는 국부부식이 전혀 발생되지 않았다. 무게감소 측정결과 HYBRID 제염조건에서는 1.3×10-3 μm/h 이하의 매우 낮은 부식속도를 나타내었다. 반면에, OA 제염제의 경우 Alloy600은 4.0×10-2 μm/h 로 비교적 균일한 부식율을 나타내었으나, 304 SS의 경우 pH = 2.0 이하에서 급격한 가속부식을 나타내었다. HYBRID 제염제의 경우 일반부식에서뿐만 아니라 crevice 부식조건에서도 거의 부식이 일어나지 않아 PWR 계통제염 시 산화막 용해 후 제염제가 계통재료에 노출되어도 재료의 건전성이 입증되었다.

다국어 초록 (Multilingual Abstract)

Crevice corrosion tests were conducted to examine the corrosion properties of HYBRID (HYdrazine Base Reductive metalIon Decontamination) which was developed to decontaminate the PWR primary coolant system. To compare the corrosionproperties of HYBRID with commonly existing decontamination agents, oxalic acid (OA) and citric oxalic acid (CITROX)were also examined. Type 304 Stainless Steel (304 SS) and Alloy 600 which are major components of the primary coolantsystem in Pressurized Water Reactor (PWR) were evaluated. Crevice corrosion tests were conducted under very aggressiveconditions to confirm quickly the corrosion properties of primary coolant system structure components which have highcorrosion resistance. Pitting and IGA were occurred in crevice surface under OA and CITROX conditions. But localizedcorrosion was not observed under HYBRID condition. Very low corrosion rate of less than 1.3×10-3 μm/h was observedunder HYBRID condition for both materials. On the other hand, under OA condition, Alloy 600 indicated comparativelyuniform corrosion rate of 4.0×10-2 μm/h but 304 SS indicated rapid accelerated corrosion in lower case than pH 2.0. Incase of HYBRID condition, general corrosion and crevice corrosion were scarcely occurred. Therefore, material integrityof HYBRID in decontamination of primary coolant system in pressurized water reactor (PWR) reactor was conformed.

목차 (Table of Contents)

• Abstract
• 요약
• 1. 서론
• 2. 실험 방법
• 2.1 Crevice 시험시편 및 제염제 준비
• 2.2 틈부식 실험
• 3. 실험 결과 및 고찰
• 3.1 제염제의 영향
• 3.2 pH의 영향
• 3.3 CRUD 및 oxalate 형성 고찰
• 3.4 HYBRID 제염제의 부식 및 제염성능
• 4. 결론
• 감사의 글
• REFERENCES

참고문헌 (Reference)

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