Friday, June 23, 2017

NRC: What are the Lessons Learned from Fukushima?


What are the Lessons Learned from Fukushima?

Lessons Learned Logo After the Fukushima accident, a task force of senior NRC staff reviewed the circumstances of the event to determine what lessons could be learned. In July 2011, the task force provided recommendations to enhance U.S. reactor safety, and these became the foundation of the NRC's post-Fukushima activities. The Commission then approved a three-tiered prioritization of the recommendations as summarized below (note that Recommendation 1 is being addressed outside of the three tiers).
Post Fukushima Safety

Tier 1 Activities

Activity Brief Description NRC Addressing by…
Mitigation Strategies
a brown circle outline with a brown, rectangle on and off switch in the middle of the circle with the swith in the On position and the words On and Off		 To enhance the capability to maintain plant safety during a prolonged loss of electrical power. Order
Containment Venting System
a brown outline of a domed nuclear reactor building with a white square representing a reactor and a connected vent stack with a white dotted line arrow going up the vent stack		 To provide a reliable hardened containment vent system for boiling water reactors (BWRs) with Mark I or Mark II containment designs. Order
Spent Fuel Pool Instrumentation
a brown circle with a 3 sided rectangle with short end top open in the center; inside the rectangle are 3 horizontal arrows pointing from the right to left side with the lower arrow having 6 vertical bars or lines tight together extending down to the bottom short end of the rectangle		 To provide a reliable wide-range indication of water level in spent fuel storage pools. Order
Seismic Reevaluations
a brown circle with a graph representation in the center		 To reanalyze potential seismic effects using present-day information to determine if safety upgrades are needed. Request for Information
Flooding Hazard Reevaluations
a brown circle with brown water covering the lower half of the circle 		To reanalyze potential flooding effects using present-day information to determine if safety upgrades are needed. Request for Information
Seismic and Flooding Walkdowns
a brown circle outline with a brown shape of a man wearing a hard hat, holding a flashlight and walking down stairs		 To inspect existing plant protection features against seismic and flooding events, and correct any degraded conditions Request for Information
Emergency Preparedness – Staffing and Communications
a brown bell image with two curved lines on either side, signifying the bell is ringing		 To assess staffing needs and communications capabilities to effectively respond to an event affecting multiple reactors at a site. Request for Information
Station Blackout Mitigation Strategies
a brown circle outline with a brown, rectangle on and off switch in the middle of the circle with the swith in the On position and the words On and Off		 To enhance the capability to maintain plant safety during a prolonged loss of electrical power. Rulemaking
Onsite Emergency Response Capabilities
a drawn image of a brown loose-leaf binder page with two paragraphs of simulated written information each with a large check mark to the left of each paragraph.		 To strengthen and integrate different types of emergency procedures and capabilities at plants. Rulemaking
Filtration and Confinement Strategies
a brown outline of a domed nuclear reactor building with a white square representing a reactor and a connected vent stack with a white dotted line arrow going up the vent stack		 To evaluate potential strategies that may further confine or filter radioactive material if core damage occurs Rulemaking
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Tier 2 Activities

Activity Brief Description NRC Addressing by…
Spent Fuel Pool Makeup Capability To provide a reliable means of adding extra water to spent fuel pools Order [consolidated into Mitigation Strategies]
See COMSECY-13-0002 and its associated approval for details
Emergency Preparedness To address three aspects of Emergency Preparedness for multi-reactor and loss of power events:
  1. Training and exercises (drills)
  2. Equipment, facilities, and related resources
  3. Multi-unit dose assessment capability
 Order [aspects (1) and (2) consolidated into Mitigation Strategies]
NRC-endorsed industry initiative [to address aspect (3)]
See COMSECY-13-0010 and its associated approval for details
"Other" External Hazard Reevaluations To reanalyze the potential effects of external hazards other than seismic and flooding events (which are being addressed under Tier 1). Request for Information [planned]
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Tier 3 Activities

Plans for addressing each of these activities are available in Enclosure 3 to SECY-12-0095
Activity Brief Description NRC Addressing by…
Periodic Confirmation of External Hazards To ensure external hazards, such as seismic and flooding effects, are periodically reanalyzed during the lifetime of a plant. Rulemaking [planned]
Seismically-Induced Fires and Floods To evaluate potential enhancements to the capability to prevent or mitigate seismically‑induced fires and floods. Longer-term evaluation
Venting Systems for Other Containment Designs To evaluate the need for enhancements to venting systems in containment designs other than Mark I and II (which are addressed under Tier 1). Longer-term evaluation
Hydrogen Control To evaluate the need for enhancements to hydrogen control and mitigation measures inside containment or other plant buildings. Longer-term evaluation
Emergency Preparedness To evaluate additional enhancements to Emergency Preparedness (EP) programs that go beyond the Tier 1 and Tier 2 EP-related activities. Longer-term evaluation
Emergency Response Data System (ERDS) Capability To enhance the capabilities of the Emergency Response Data System (ERDS) Longer-term evaluation
Decision-making, Radiation Monitoring, and Public Education To evaluate the need for enhancements to Emergency Preparedness programs in the areas of decision-making, radiation monitoring, and education. Longer-term evaluation
Reactor Oversight Process (ROP) Updates To modify the Reactor Oversight Process to reflect any changes to the NRC's regulatory framework (which is being pursued under a separate activity). Dependent on Regulatory Framework activity
Training on Severe Accidents To enhance training of NRC staff on severe accidents and related procedures. Dependent on outcome of Onsite Emergency Response Capabilities (Tier 1)
Emergency Planning Zone To evaluate whether the basis for the size of the emergency planning zone needs to be modified. Longer-term evaluation
Potassium Iodide (KI) To evaluate the need to modify existing programs for the pre-staging of potassium iodide. Longer-term evaluation
Expedited Transfer of Spent Fuel to Dry Cask Storage To evaluate the merits of expediting the transfer of spent nuclear fuel from storage pools to dry cask storage. See this staff memo to the Commission and staff requirements memorandum for more details
Reactor and Containment Instrumentation To evaluate potential enhancements for instrumentation in the reactor and containment that can withstand severe accident conditions. Longer-term evaluation
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