1980: Formation of the Institute of Nuclear Power Operations (INPO). This organization accredits training programs, conducts site inspections, and shares lessons learned and operational information throughout the industry, all with a goal of ensuring that plants achieve excellence above and beyond regulatory requirements.
1980s: Expanded use of probabilistic risk assessment (PRA). This is a rigorous method to identify events that could impact the safety of a plant, and the associated event likelihoods and consequences. PRAs estimate the frequencies of events leading to reactor core damage and releases of radioactivity, and the consequences in terms of injuries and damage to environment. Plant operators use the insights from PRA studies to better understand the strengths and weaknesses of their plant’s design and operation.
1980s: Implemented hardware and procedure changes to ensure that safety equipment would continue to function in harsh post-accident environments (e.g., in the presence of high radiation and temperature levels, steam, etc.).
1980s: Developed emergency operating procedures. These symptom-based procedures were based on lessons learned from the Three Mile Island accident and developed for all reactor types.
1988: The NRC finalized the station blackout rule. This rule changed regulations to provide further assurance that a loss of both off-site and on-site emergency AC power systems would not adversely affect public health and safety. The rule requires that plants be capable of withstanding a station blackout for a specified duration and maintaining core cooling during that period.
1991: The NRC finalized the maintenance rule. These regulations require plant owners to develop programs that periodically assess the effectiveness of their maintenance activities to help assure that safety equipment remains able to perform safety functions.
1993: The NRC finalized the training rule. These regulations require training programs that ensure personnel have the knowledge and qualifications to effectively perform their jobs. In particular, training programs on safety must utilize the rigorous Systematic Approach to Training (SAT) to develop course content, delivery and evaluation.
1990s: Established severe accident management guidelines. These guidelines provide strategies to manage the consequences of an accident involving potential or actual damage to the reactor core. The strategies are intended to arrest the progression of fuel damage, maintain the capability of the containment as long as possible, and minimize radiological releases.
2002-2010: Post-9/11 changes include identifying potential vulnerabilities associated with the impact of a large aircraft. Site enhancements and operating practices were implemented to mitigate scenarios involving the loss of large areas of a plant due to explosions or fire. Changes also included additional methods and procedures to provide cooling to the reactor and the used fuel pool and the staging of additional emergency equipment at every plant site. Emergency plans were also revised to ensure that plant operators could effectively coordinate their responses with law enforcement agencies. Over the past decade, there have been more than $2 billion in additional security-related expenditures in this area.
2003: The industry developed a materials reliability initiative to address the reactor vessel head degradation issue uncovered at the Davis-Besse plant in 2002. The initiative was spearheaded by an oversight group composed of senior industry executives with broad experience in materials issues. The purpose was to address these issues strategically and proactively through additional research, enhanced inspections and implementation of mitigation and repair activities. Industry and INPO also introduced initiatives to strengthen the safety culture at each site.
2011: INPO compiled a detailed timeline of events at the Fukushima Daiichi nuclear power station after the March 11 earthquake and tsunami. A detailed report was prepared to identify and promote application of the relevant safety lessons.
2012: Conducted inspections, or "walkdowns," of every U.S. nuclear plant site focused on their currently installed seismic and flooding protection features. The plants had to ensure the features met current requirements and also identify, correct, and report any degraded conditions. The plants completed their walkdowns by November 2012; NRC inspectors have done follow-up inspections, and the agency has issued plant-specific assessments of the licensee's walkdown reports.
2012-2018: FLEX capabilities were added to extreme natural events response measures. This effort involved the addition of more portable, backup safety equipment at each reactor site, including generators, diesel-driven pumps and satellite phones. The additional portable equipment ensures that power and water will remain avaliable to maintain key safety functions in the absence of AC power and heat transfer capability from permanently installed safety systems. The key safety functions are reactor core cooling, used fuel pool cooling and containment integrity.
2014: The industry added another layer of public protection with the opening of two national response centers in Memphis and Phoenix as part of post-Fukushima safety strategy enhancements. Both centers maintain multiple complete sets of portable emergency equipment to help facilities respond safely to extreme events, no matter the cause. This equipment supplements the permanent safety systems built into every nuclear power facility and the multiple sets of portable, backup safety equipment already positioned at each site. The national response centers have made arrangements to ensure that their emergency equipment can be delivered to any affected site within 24 hours of an extreme event.