The effects of electrochemical parameters in terms of electrochemical potential on stress corrosion cracking growth rates of au stenitic stainless steels in high temperature pure water are analyzed based on obtained experimental results and reported data. The effect of decreasing electrochemical potential is more significant in non-hardened sensitized and non-hardened stainless s teels than that in strain-hardened stainless steels, which is also supported by the results of Ni-base alloys and weld metals....
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Effects of Electrochemical Parameters on SCC of Stainless Steels inSimulated BWR Environments

A concept of a plutonium burner HTGR (High Temperature Gas-cooled Reactor) with a high nuclear proliferation resistance has been proposed by Japan Atomic Energy Agency. In addition to the high nuclear proliferation resistance, in order to attain the high burn-up, we propose to introduce a PuO2-YSZ (Yttria Stabilized Zirconia) fuel kernel with ZrC coating to the plutonium burner HTGR. In this study, we conduct design of the coated fuel particle and of the reactor core to confirm the feasibility of the plut...
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Design Study on Fuel and Reactor Core for Plutonium Burner High Temperature Gas-cooled Reactor

Results of irradiation experiment on the degradation of ductility of 8-9Cr reduced activation ferritic/martensitic steels are introduced, including those of irradiated austenitic steels. M acroscopic models of post irradiation tensile and fatigue properties obtained from the results are shown. Concept of the models should be essential for future design criteria development....
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Ductility loss of materials by neutron irradiation and structural integrity of reactor core

The authors have proposed a novel eddy current testing(ECT) probe for thick-walled plates. A basic concept of the probe is that a couple of differential pick-up coils is arranged between two exciting coils carrying currents opposite to each other. This arrangement allows strong eddy currents opposite to scan surfaces and the weak decay of eddy currents in the thickness direction. In this study, the present probe was applied to ECT of welding area. For the purpose, experiments were carried out u...
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Weld Inspection Using Eddy Current Testing Probe for Thick-walled Plates

In order to grasp efficiency of risk information, we tried to apply an insight of PRA to considering of severe accidents; TMI, Chernobyl, and Fukushima Dai-ichi. Based on this analysis, three points are disclosed. At first, PRA can product adequate countermeasures for low-likelihood events; huge earthquake or Tsunami. Next, PRA can prove weak points in design or operation reasonably. Third point is safety culture. PRA and safety culture are seemed to be connected deeply. These analyses revealed PRA is on...
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-For Discussions with the Public for the Safety of Nuclear Power -Applying Risk Information to Prevention/Mitigation of SA-

Target of PRA is not calculating PRA to get CDF/CFF, but providing significant and useful information from PRA results for risk-informed activities. Lot of risk applications have been implemented these about 20 years in US. After Fukushima Dai-ichi accidents, Japanese Nuclear Regulation Authority provided new regulatory requirements about external events and beyond design events. And Risk Application faces full-scale implementation. In this report, several methods of risk application are showed with adeq...
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- For Discussions with the Public for the Safety of Nuclear Power -Various Patterns of Risk Application Method and Examples-

After Fukushima daiichi nuclear accident, it becomes more important risk communication with the public. In discussions with the public in nuclear safety, communication and discussions on risks that not only nuclear risks also social risks are important. Differences in viewpoints, understanding, and thought about risks become communication difficult. We need to discuss risks fairly, appropriately with the public and reduce total social risks. ...
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For Discussions with the Public for the Safety of Nuclear Power -Discussion with the Public -

1.はじめに 「安全」はリスクを尺度として測ることができる。言 い換えれば、リスク評価は安全を考える上で必須となる。 本報では、原子力安全におけるリスク評価(定量化)と 地震等の外的事象への適用についてその概要を解説する。 原子力安全の目的は「人と環境を、原子力の施設と活 動に起因する放射線の有害な影響から防御すること」[1] であり、一般的な産業活動における安全(労働災害から の安全等)とは個別に扱われる。従って原子力安全にお けるリスクとは、放射線の有害な影響に関するリスク(放 射線リスク)となる。 ......
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For Discussions with the Public for the Safety of Nuclear Power - Risk Assessment for Nuclear Safety and Application to External Event -

In considering nuclear safety, it is an important task to clarify the relationship with peace of mind that is the heart of people. What is the state that scientific safety is something that people feel safe. We considered the relationship between quantified risk and safety, and ways to acquire peace of mind. We analyzed the thresholds of safety risks as a social common sense, showed a safe condition, and showed the importance of forming a consensus to obtain peace of mind. ...
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For Discussions with the Public for the Safety of Nuclear Power -Safety and Secure-

1.はじめに 社会においては、リスクの理解は様々である。リスク をどのように理解していけば良いのかを示し、リスクについての社会との向き合い方をまとめる。個人のリスク の受け入れは個人で行うものであるが、 社会のリスクは、社会としていかなるリスクを許容するかという仕組みを社会で構築する必要がある。そのためにも、社会リスクとはどんなものであり、どのように社会また個人は、それにどう向き合い、受け入れるリスクの選択をどう行うべきかを述べる。また、原子力リスクの考え方とそれを 一般公衆に対する防災の観点からどのよう......
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For Discussions with the Public for the Safety of Nuclear Power -Social risk and Nuclear risk -