ML20289A650

Enclosure 2 - NRC Presentation on History of 10 CFR 50.155

ML20289A650
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Issue date:	10/08/2020
From:	Tim Reed Division of Operating Reactor Licensing
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Kichline M
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History of 10 CFR 50.155 Mitigation of Beyond-Design-Basis Events Requirements Tim Reed USNRC September 2020 1

Events Leading to New Mitigation Strategy Requirements

• Earthquake in Japan occurs - March 11, 2011

• Near-Term Task Force (NTTF) was formed and generates its recommendations (NTTF Report)-

July 2011

• Commission issues its staff requirements memo (SRM) on the NTTF report in August 2011

• Commission issues its SRM on SECY-11-0124 and SECY-11-0137 2

Post-Fukushima Regulatory Actions (During 2012)

NRC Orders Issued on March 12, 2012:

- EA-12-049 (Mitigation Strategies)

- EA-12-050 (Mark I/II Hardened Containment Vents - becomes EA-13-109)

- EA-12-051 (Spent Fuel Pool Instrumentation)

NRC Issues 10 CFR 50.54(f) Requests for Information on March 12, 2012 Two Advance Notice of Proposed Rulemakings (ANPR) issued

- Station Blackout ANPR issued March 2012

- Onsite Emergency Response Capabilities issued in April 2012 NRC and industry develop and issue EA-12-049 implementing guidance in August 2012 (JLD-ISG-2012 endorses NEI12-06 rev 0) 3

Mitigation of Beyond-Design-Basis Events (MBDBE) Rulemaking

• Proposed MBDBE Rule issued for public comment in November 2015

• Draft Final MBDBE rule provided to the Commission in December 2016 (SECY-16-0142)

• Commission acts on final rule (SRM-SECY-16-0142) in January 2019

• Final MBDBE rule issued August, 9, 2019 with effective date of September 9, 2019 4

Impact of Changes to MBDBE rule

• Final Rule 10 CFR 50.155 aligns closely with Orders EA 049 and EA-12-051

• Removed draft requirements not supportable under backfit or moved back into 50.54(f)

- Seismic and flooding reevaluated hazards addressed on plant-specific basis under 10 CFR 50.54(f)

- Any additional requirements must meet backfit

• Impacted Guidance: Draft Regulatory Guide 1.228 was discontinued

• Impacted Regulatory Guide 1.226

- Guidance for addressing reevaluated hazards in appendices G and H not required for compliance with 10 CFR 50.155 5