Experience of improvement of Nuclear Regulation in Japan Yutaka HARA - - PowerPoint PPT Presentation

Yutaka HARA

Director, International Affairs Office Nuclear Regulation Authority (NRA) JAPAN

20 September 2017, IAEA GC 2017 “Effective Partnerships for Nuclear Safety and Security in the Arab Region” , Vienna

Experience of improvement

• f Nuclear Regulation in Japan

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Ⅰ New regulatory requirements

• n Lessons Learned

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 Large scale common cause failures due to extreme natural

hazards led to long lasting SBO / LUHS, resulting in severe accidents.



Enhanced measures against natural hazards

 Not only earthquakes and tsunamis but also volcanic activities,

tornadoes, forest fires, etc.



Enhanced reliability of safety functions such as power supply

 Use of mobile equipment, strengthened “diversity”



Mandatory measures against severe accidents

 Prevention and mitigation of core damage  Suppression of radioactive materials

dispersion



Back-fitting to existing plants

SBO: Station Blackout LUHS: Loss-of Ultimate Heat Sink

New Requirements Based on Lessons Learned

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Comparison between Previous and New Requirements

Seismic / Tsunami resistance Natural phenomena

<Previous requirement>

Reliability of power supply Function of other SSCs* Fire protection Seismic / Tsunami resistance Natural phenomena

(Volcano, Tornadoes, Forest fire: New)

Prevention of core damage (Postulate multiple failures) Suppression of radioactive materials dispersal Response to intentional aircraft crash Prevention of CV failure & large release Function of other SSCs Internal flooding (New) Fire protection Reliability of power supply

<New requirement>

Reinforced & New (Against SA* & Terrorism) New Reinforced & New 3rd Layer

• f DiD

4th Layer

• f DiD*

Design basis to prevent severe accidents (Confirm that a single failure would not lead to core damage)

DiD* : Defense in Depth SSCs*: Structure, Systems and Components SA* : Severe Accident

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 Accurate Evaluation Method on Earthquake and Tsunami ; Particularly Enhanced Tsunami Measures

Define “Design Basis Tsunami” that exceeds the largest in the historical records and require to take protective measures such as breakwater wall based on the design basis tsunami SSCs for Tsunami protective measures are classified as Class S equivalent to RPV* etc. of seismic design importance classification Enlarged application of higher seismic resistance More stringent standards on Tsunami

＜Example of tsunami countermeasures（multiple protective measures）＞

Tsunami Guard (prevent water from flowing into the building)

*RPV: Reactor Pressure Vessel

Tsunami Guard Breakwater Wall (prevent inundation to the site)

(Example) Measures against Tsunamis

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As of 1 September 2017, 16 PWRs and 10 BWRs have filed application. Five PWRs are in operation. (Sendai 1&2, Ikata 3 and Takahama 3&4 )

Application PWR 16 BWR 10 Total 26

＜Tomari＞ ＜Higashidori(Tohoku Co.) ＞ ＜Onagawa＞ ＜Fukushima Dai-ichi＞ ＜Fukushima Dai-ni＞ ＜Tokai Plant, Tokai Dai-ni＞ ＜Hamaoka＞ ＜Ikata＞ ＜Sendai ＞ ＜Genkai ＞ ＜Shimane ＞ ＜Takahama＞ ＜Ohi ＞ ＜Kashiwazaki Kariwa＞ ＜Shika＞ ＜Mihama ＞ ＜Tsuruga＞

Reactors undergoing decommissioning (9) Specified nuclear facility BWR (22) PWR (20) Restarted (5) Applied (26)

＜Ohma＞

BWR, under Construction

+

＜Higashidori(TEPCO)＞

Status of Conformity Review for Nuclear Power Plants

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Ⅱ Continuous Improvement of Nuclear regulation

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• Continuous improvement of ordinances

and guides

• Amendments of NRA ordinances and guides

will be continuously done through the NRA’s improvement process of regulation based on new knowledge and experience.

• For Example

Single-phase open circuit Toxic gas releases HEAF: High Energy Arcing Faults

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• Back-fitting
• New regulatory requirements are being back-

fitted to the existing plants under the legal framework

• New requirements based on the lessons

learned from the Fukushima Daiichi accident

• Amendments of the requirements triggered

by operating experience and new technical knowledge

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Ⅲ IRRS Mission

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In IRRS Mission report, 2 good practices, 13 recommendations and 13 suggestions are indicated. ⇒ NRA has responded to them in an effective manner since right after receiving these.

Inspection Program

NRA has been working to introduce NRA’s new inspection system and amended the Reactor Regulation Act in 2017.

Regulation for Radioisotope (RI)

NRA has been working on strengthening RI security and clarifies the responsibility of RI users etc. and also amended the Radioisotope Regulation Act in 2017.

Human Resource Development

NRA started a plan to increase and secure qualified staff as well as to improve NRA’s education and training system for expertized personnel.

Management System

NRA improved and systematized its management system to more sophisticated one.

Major items Responses

 Date: 11-22 Jan, 2016, including other stakeholders’ interviews and site visits

Overview of IRRS Mission in 2016

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Benefits gained from IRRS Mission

 IRRS is used as an effective tool to strengthen nuclear safety in Japan ( Ex. Acts were amended to enhance NRA’s regulation. )  NRA gained international knowledge and practice through discussion with IRRS reviewers.  NRA developed its knowledge and understanding of IAEA standards through the self assessment for IRRS. The following points are important:  Conduct IRRS mission on a regular basis to find challenges for nuclear safety  Conduct Follow-up mission (after summer in 2019 )

(Japan did not host a follow-up mission after the IRRS mission in 2007)

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 NRA was established under the lessons learned from Fukushima Daiichi Accidents just five years ago.  NRA has been pursuing and will pursue “continuous improvement of safety”.  NRA will make efforts to further enhance nuclear safety and security in Japan through IAEA peer review services (IRRS and IPPAS Follow-up Missions a few years later.).  NRA would share experiences with other countries through opportunities such as IAEA GC side-events, RCF activities, review meetings of JC/CNS, safeguard training programs supported by IAEA/ MEXT and

• ther IAEA TMs.

Ⅳ Conclusion

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Thank you for your attention.

http://www.nsr.go.jp/english/

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Appendix

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NRA’s Commissioners

Chairman Toyoshi Fuketa Commissioner Shinsuke Yamanaka Commissioner Satoru Tanaka Commissioner Nobuhiko Ban Commissioner Akira Ishiwatari

As of September 22 2017

16 The Secretariat of the NRA

Secretary-General

Nuclear Regulation Policy Planning Division Director-General, Nuclear Regulation Department

Deputy Secretary-General

Public

Deputy Secretary-General for Technical Affairs (Chief Engineering Officer) Nuclear Regulation Department

*1 Research for Reactor System Safety, Research for Severe Accident, Research for Nuclear Fuel Cycle and Research for Radioactive Waste, Earthquake and Tsunami *2 Licensing for Nuclear Power Plants, Licensing for Research Reactors, Use of Nuclear Material and Specified Nuclear Facilities, Licensing for Nuclear Fuel Facilities, Licensing for Earthquake and Tsunami Measure *3 Oversight of Nuclear Power Plants, Specified Oversight, Oversight of Nuclear Fuel Related Facilities and Research Reactors

Number of staff: about 1,000

As of July, 2017

Fire Management Office Director-General for Emergency Response Director-General for Radiation Protection Strategy and Security Director-General (3) Director for Cybersecurity and Information Technology

Secretary-General’s Secretariat

Divisions of Oversight(3) *3 Oversight Planning and Coordination Division Divisions of Licensing(4) *2

Licensing Oversight

Division of Budget and Accounting Personnel Division Divisions of Research(4) *1 Regulatory Standard and Research Division Regulatory Standard and Research Department Division of Legal Affairs Radiation Protection Policy Planning Division Radiation Monitoring Division Division of Nuclear Security Safeguards Office Division of Regulation for Radiation

Radiation Protection Department

Litigation Office Accidents Response Office International Affairs Office Public Information Office Management SystemOffice Policy Planning and Coordination Division

Organizational Chart of the NRA Secretariat