U.S. NRC – Today and Tomorrow Marc Dapas Regional Administrator NRC Region IV

NRC MISSION The NRC licenses and regulates the Nation's civilian use of radioactive materials to protect public health and safety, promote the common defense and security, and protect the environment.

NRC's regulatory mission covers three main areas: reactors, materials, waste

NRC REGIONS

Operating Reactor Sites by NRC Region

PRESSURIZED WATER REACTOR

BOILING WATER REACTOR

LOCATIONS OF NRC-LICENSED URANIUM RECOVERY SITES

LOCATIONS OF FUEL CYCLE FACILITIES

Defense in Depth Any complex, close-coupled, system, no matter how well-engineered, cannot be said to be failure-proof. That is especially true if people operate controls that determine how the system performs. Defense in depth creates multiple independent, and redundant layers of protection, and response to failures, accidents, or fires in power plants. The idea is that no single layer, no matter how robust, is exclusively relied upon; access controls, physical barriers, redundant and diverse key safety functions, and emergency response measures are used. Defense in depth is designed to compensate for potential human and mechanical failures, which will occur.

Defense in Depth Ideal view of Defense in Depth barrier versus The fact that barriers may have weaknesses or “holes” in the barrier.

Emergency Planning Zones

Nuclear Share of Electricity Generated by Country

US NET ELECTRICITY GENERATION BY ENERGY SOURCE This slide shows the most recent EIA Data regarding the US electricity mix by power source.

U.S. Net Generation By Source 2001 vs 2015 This slide compares net generation in 2001 with net generation in 2015. Note: - Overall decrease in net generation - Large Decrease in coal generation - Large Increase in natural gas generation - Decrease in nuclear generation - Increase in hydro generation

Browns Ferry Fire - 1975 • A fire at Browns Ferry Nuclear Power Plant fundamentally changed how the NRC dealt with Fire Protection. • Workers testing fire barriers for air leaks using a candle ignited the barrier and the cables that penetrated it. • The fire burned for 7 hours and affected over 1600 cables, including 628 cables important to safety. • Operators could not monitor the plant normally and had to conduct emergency repairs in order to shut the reactor down. • In response, the NRC revised fire protection regulations to require plants to maintain safe shutdown capability in the event of a fire by: 1) minimizing the potential for fires, 2) rapidly detecting and extinguishing fires, and 3) ensuring that operators can safely shut down the reactor in the event of a fire.

Three Mile Island - 1979 - March 1979: TMI-2 experienced a loss of feed, turbine trip, and reactor shut down. - Primary pressure increased, PZR PORV opened and stuck open -> LOCA - Control room instrumentation indicated PORV closed; operators were unaware of LOCA - No instrumentation to indicate water level in the reactor core. - RCPs shutdown due to pressure drop. - Operators reduced ECCS flow to prevent the pressurizer from going solid. - Inadequate core cooling due to reduced ECCS flow  CORE MELTDOWN - Containment remained intact and held most of the accident’s radioactive material (there were some releases) - Approx 2 million people in the vicinity of the plant received an average dose of 1 mR above background - IMPACT OF ACCIDENT ON REGULATION: - Upgrading and strengthening of plant design and equipment requirements. This includes fire protection, piping systems, auxiliary feedwater systems, containment building isolation, reliability of individual components (pressure relief valves and electrical circuit breakers), and the ability of plants to shut down automatically; - Identifying the critical role of human performance in plant safety led to revamping operator training and staffing requirements, followed by improved instrumentation and controls for operating the plant, and establishment of fitness-for-duty programs for plant workers to guard against alcohol or drug abuse; - Enhancing emergency preparedness, including requirements for plants to immediately notify NRC of significant events and an NRC Operations Center staffed 24 hours a day. Drills and response plans are now tested by licensees several times a year, and state and local agencies participate in drills with the Federal Emergency Management Agency and NRC; - Expanding NRC's resident inspector program – first authorized in 1977 – to have at least two inspectors live nearby and work exclusively at each plant in the U.S. to provide daily surveillance of licensee adherence to NRC regulations; - Installing additional equipment by licensees to mitigate accident conditions, and monitor radiation levels and plant status;

Chernobyl - 1986 - April 26, 1986, sudden surge of power during reactor systems test destroyed Chernobyl unit 4. - 28 workers killed by radiation within 4 months of the accident. - 106 workers received enough dose to get acute radiation sickness. - 200,000 cleanup workers received doses of 1-100 REM - Contaminated wide areas of Belarus, the Russian Federation, and Ukraine. - Many children and adolescents in the area in 1986 drank milk contaminated with radioactive iodine, which delivered substantial doses to their thyroid glands. To date, about 6,000 thyroid cancer cases have been detected among these children. Ninety-nine percent of these children were successfully treated; 15 children and adolescents in the three countries died from thyroid cancer by 2005. - NRC continues to conclude that many factors protect US reactors from the combination of problems that led to Chernobyl, including plant design, safe shutdown capabilities, containment structures. - in 1989 NRC concluded that the lessons learned from Chernobyl did not dictate requiring immediate changes in NRC regulations. - NRC gained valuable insight from the accident, especially lessons in decontamination.

Davis Besse - 2002 - In Feb, 2002, during a RFO, a reactor vessel head inspection identified cracking and RCS boundary leakage on 3 CRDM nozzles. During subsequent repairs, one of the CRDM nozzles was mechanically agitated and displaced (fell over). Subsequent investigation revealed severe wastage of the low alloy steel of the RPV head extending 5 inches downhill from the CRDM penetration and 4-5 inches at its widest. The minimum thickness of the remaining RPV head was 3/8 inch, and was attributed to the 3/8 inch thick stainless steel cladding on the inside surface of the RPV head. NRC commissioned a task force to evaluate lessons learned and implemented several changes including: An assessment of stress corrosion cracking and boric acid corrosion to support and evaluate changes to ASME section XI requirements as well as changes to NRC inspections of boric acid corrosion control programs. Development of an NRC OE framework and revision of NRC inspection procedures to review industry use of operating experience Revised PI&R inspection procedure and IMC 0350 guidance Evaluated licensee RCS leakage Tech Specs, revised inspection guidance to require NRC monitoring of licensee RCS leakage.

Fukushima - 2011 - March 11, 2011 9.0 earthquake, Fukushima loses offsite power, Operating units 1,2,3 shut down. (units 4,5,6 already shutdown with unit 4 defueled). For each of units 1 – 3, the following sequence occurred: • Earthquake (.56g; 125% design basis) results in: • Reactor Scram. • Loss of offsite AC Power; start of Emergency Diesel Generators. • Operators controlling critical plant parameters with safety-related equipment. • Tsunami (46 feet; 250% design basis) results in: • Loss of Emergency AC Power Distribution due to flooding. • Loss of Battery (DC) power distribution due to flooding (Unit 2 retained limited DC for a while). • Operators lose control of critical plant parameters when safety-related equipment is lost • Overpressure protection operation of safety relief valves depletes reactor coolant. • Reactor coolant loss results in fuel clad overheating. • Fuel clad overheating results in accelerated corrosion rates. • Corrosion results in clad failure (first fission product barrier loss) and large volumes of hydrogen produced as well as radioactive contents release. • Vessel overpressure protection valves relieve vessel hydrogen and radioactive contents to suppression pool (second fission product barrier loss). • Suppression pool reaches boiling temperatures while hydrogen accumulates. • Primary containment pressurizes due to suppression pool boiling. • Primary containment is intentionally vented or fails due to over pressurization (third fission product barrier loss). • Containment contents, including hydrogen, vent to reactor building atmosphere • Hydrogen in air at 18 to 58% is explosive (detonation range). • Reactor Building explodes resulting in direct release pathway of core materials to environment.

NRC POST FUKUSHIMA SAFETY ENHANCEMENTS • March 23, 2011, an NRC Chairman Tasking Memorandum established the Near Term Task Force responsible for collecting and evaluating information and making recommendations to the Commission. • On July 13, 2011, the Commission was presented the written report, SECY-11-0093, “Near Term Report and Recommendations for Agency Actions following the Events in Japan,” dated July 12, 2011 (ADAMS Accession No. ML11186A950). • On July 19, 2011, the Task Force presented the recommendations verbally to the Commission. • On October 3, 2011 the NRC Staff proposes a prioritization plan for implementing the Task Force recommendations, SECY-11-0137, “Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned” • On December 15, 2011, the Commission approved the prioritization plan for the Task Force Recommendations.

NRC POST FUKUSHIMA SAFETY ENHANCEMENTS Prioritization Plan • TIER 1 Those recommendations that should be implemented without unnecessary delay and for which sufficient resources are available Includes: Mitigation Strategies (order), Containment Venting System (order), SFP Instrumentation (order), Seismic Reevaluations (RFI), Flooding Hazard Reevaluations (RFI), Seismic and Flooding Walkdowns (RFI), EP staffing and communications (RFI), SBO mitigation strategies (rulemaking), Onsite emergency response capabilities (rulemaking), Filtration and Confinement strategies (rulemaking) • TIER 2 Those recommendations that cannot be initiated in the near term due to factors that includes the need for further technical assessment and alignment, dependence on Tier 1 issues, or availability of critical skill sets. Includes: SFP makeup capability (order), EP related to multi-reactor and loss of power events (order), “Other” hazard reevaluations (RFI). • TIER 3 Those recommendations that require further staff study to support a regulatory action, have an associated shorter-term action that needs to be completed to inform the longer-term action, or are dependent on the availability of critical skill sets. Includes: periodic confirmation of external hazards (planned rulemaking), various long term evaluations

NRC POST FUKUSHIMA MITIGATION STRATEGIES

FLEX EQUIPMENT

Hardened Vents and Filtration  (Boiling Water Reactors with Mark I and Mark II containment designs) The Fukushima accident disabled the plants' ability to cool their reactor cores, causing heat and pressure to build within the concrete containment buildings that eventually damaged the containments and allowed radioactive material to reach the environment. To prevent this, the NRC issued an Order on March 12, 2012, requiring all U.S. nuclear power plants with the Fukushima-style containment design to install a reliable, hardened vent that can remove heat and pressure before potential damage to a reactor core occurs. This not only helps preserve the integrity of the containment building, but can also help delay reactor core damage or melting.  (EA 12-050) After issuing the order, additional NRC evaluations examined the benefits of venting after reactor core damage occurs.  In June 2013, the NRC modified the Order to ensure those vents will remain functional in the conditions following reactor core damage. (EA 13-109)   The NRC considered revising its regulations through the rulemaking process to include strategies for filtering or otherwise confining radioactive material that gets released as a reactor core is damaged. In August 2015, the Commission directed the staff not to proceed further with the rulemaking. (SECY-15-0085 and associated staff requirements memorandum)

Simplified Hardened Containment Vent System (HCVS)