HomeRadioactive WasteStorage of Spent Nuclear Fuel

# Spent Fuel Storage in Pools and Dry Casks Key Points and Questions & Answers

On this page:
        - Questions and Answers – General            - What is spent nuclear fuel?
          - Why does spent fuel need to be cooled?
          - Why not require real time radiation monitoring or EPA RadNet monitors around an independent spent fuel storage installation (ISFSI)?
          - How are licensees required to fund dry storage facilities?
          - What is high burnup fuel?
          - Could high burnup fuel degrade in storage?
          - What were the inspection results of the canisters located at the Diablo Canyon ISFSI? 
        - Questions and Answers – Spent Fuel Pool Safety            - What do you look at when you license a fuel storage facility? How do I know it can withstand a natural disaster?
          - How do you know the fuel pools are safe? Does the NRC inspect these facilities, or just the reactor itself?
          - What would happen to a spent fuel pool during an earthquake? How can I be sure the pool wouldn't be damaged?
          - Can spent fuel pools leak?
          - How would you know about a leak in such a large pool of water?
          - How can operators get water back in the pool if there is a leak or a failure?
          - Do U.S. nuclear power plants store their fuel above grade? Why is this considered safe?
          - How are spent fuel pools kept cool? What happens if the cooling system fails?
          - What keeps spent fuel from re-starting a nuclear chain reaction in the pool? 
        - Questions and Answers – Dry Cask Safety            - What is dry cask storage?
          - What is an "ISFSI"?
          - What kind of license is required for an ISFSI?
          - How does the NRC determine that a dry storage system is safe?
          - What are the requirements for the selection and use of a dry storage system at an NRC licensed commercial power reactor site?
          - What Risk Assessments have been conducted for dry storage systems?
          - How do the NRC requirements ensure that dry storage systems do not release radioactive material and expose workers and members of the public to radiation?
          - How are dry storage systems inspected?
          - What can remote visual testing be used to detect?
          - How does the NRC conduct oversight of Licensees?
          - How does the NRC verify that canisters are properly loaded in accordance with their NRC Certificate of Compliance?
          - How can the fuel or internal components be inspected on canisters with welded lids?
          - How would welded stainless steel canisters be repaired if necessary? 
        - Questions and Answers – Waste Confidence & Future Plans            - How long is spent fuel allowed to be stored in a pool or cask?
          - What is the plan for storage of spent nuclear fuel going forward? Will on-site storage continue to be the way for the foreseeable future?
          - These casks are already pretty old and could be storing spent fuel for decades to come. How can you protect them from deteriorating over time, especially from effects that have been seen at other nuclear installations such as alkali-silica reaction or chloride-induced stress corrosion cracking?
          - How are the long-term impacts of onsite storage of spent fuel analyzed, and what measures are taken to minimize potential impacts on public health and safety?
          - After a plant is decommissioned there will be no infrastructure to handle the repackaging of spent fuel if the storage systems need replacement. Is there a plan for this contingency, and what are the safety implications of reopening the storage cask? 
        - Questions and Answers – Security            - What about security? How do you know terrorists won't use all of this waste against us?
          - How are dry storage systems canisters at ISFSIs protected against terrorism such as the September 11, 2001 terrorist attacks using hijacked airplanes? 
        - Questions and Answers – Emergency Planning            - Are potential seismic effects considered in the assessment of canisters for continued operation? –EP
          - What are the emergency plans for nuclear waste at an ISFSI in the case of mishandling, leaks, natural disasters or acts of terrorisms?
          - What emergency plans are required for spent fuel storage facilities at nuclear power plants undergoing decommissioning or sites that have completed decommissioning? 

Index to all Frequently Asked Question Pages

## Questions and Answers – General

**What is spent nuclear fuel?**

"Spent nuclear fuel" refers to fuel elements that have been used at commercial nuclear reactors, but that are no longer capable of economically sustaining a nuclear reaction. Periodically, about one-third of the nuclear fuel in an operating reactor needs to be unloaded and replaced with fresh fuel.

**Why does spent fuel need to be cooled?**

Spent fuel continues to generate heat because of radioactive decay of the elements inside the fuel. After the fission reaction is stopped and the reactor is shut down, the products left over from the fuel's time in the reactor are still radioactive and emit heat as they decay into more stable elements. Although the heat production drops rapidly at first, heat is still generated many years after shutdown. Therefore, the NRC sets requirements on the handling and storage of this fuel to ensure protection of the public and the environment.

**Why not require real time radiation monitoring or EPA RadNet monitors around an independent spent fuel storage installation (ISFSI)?**

The regulations require that an independent spent fuel storage installation (ISFSI) must have the capability for continuous monitoring of the storage confinement system in a manner such that the licensee will be able to determine when corrective action needs to be taken to maintain safe storage conditions. For dry spent fuel storage, periodic monitoring is sufficient, provided that periodic monitoring is consistent with the dry spent fuel storage cask design requirements. The monitoring period must be based upon the spent fuel storage cask design requirements. Therefore, the NRC determined that adequate radiological monitoring capabilities already exist at licensed facilities.

All ISFSIs have multiple radiation monitors to ensure they meet NRC dose limits. This is typically accomplished using multiple thermoluminescent dosimeters (TLDs) on the ISFSI fence. These TLDs are regularly monitored. The results of the monitoring program are one of many items, procedures, and operations reviewed by NRC staff. NRC staff inspection reports are made publicly available, unless they contain classified, safeguards, or sensitive information.

**How are licensees required to fund dry storage facilities?**

Licensees are required to set aside funding for the management of spent fuel after a plant permanently shuts down until the fuel is transferred to the Department of Energy (DOE) for final disposal. Although the annual costs for continued storage are manageable, cumulative costs will continue to increase.

Under 10 CFR 50.54(bb), licensees are required to obtain approval from the Commission concerning the program by which they intend to manage the irradiated fuel. This includes all plans to provide funding for the management of the fuel at the reactor until title and possession of the fuel is transferred to DOE for permanent disposal in a repository.

The NRC has requirements in 10 CFR 72.22(e) for license applicants to show they have the necessary funds available to cover estimated construction costs, estimated operating costs over the license term, and estimated decommissioning costs. NRC staff review this at the time of initial license application and at the time of license renewal to determine if the applicant has demonstrated reasonable assurance that funding will remain available for the duration of the facility's license.

**What is high burnup fuel?**

Burnup is a measure of how much energy is obtained from the fission of uranium, or fuel, in the reactor. Burnup is measured in gigawatt-days per metric ton of uranium (GWd/MTU).  Spent fuel is considered high burnup at a value greater than 45 GWd/MTU.

For more information, see the Backgrounder on High Burnup Spent Fuel

**Could high burnup fuel degrade in storage?**

The NRC has conducted testing through the National Laboratories and found that high burnup fuel is robust against storage and transportation loads. The inert environment inside the casks maintained during storage provides assurance that high burn up fuel will maintain its integrity under normal and accident conditions. Ongoing long-term demonstrations of loaded high burn-up fuel with other material types are being conducted by the U.S. Department of Energy and Electrical Power Research Institute (EPRI), and are expected to confirm the previous laboratory testing.

For more information, see the following:
        - NUREG-2224 – Dry Storage and Transportation of High Burnup Spent Nuclear Fuel
        - High Burnup Dry Storage Cask Research and Development Project: Final Test Plan

 

**What were the inspection results of the canisters located at the Diablo Canyon ISFSI?**

The assessment of the conditions on the Diablo Canyon canisters are described in the Electrical Power Research Institute report EPRI-3002002822 and the Sandia National Laboratories report SAND2014-16383. The canister surfaces appeared in good condition with no signs of degradation or corrosion. Researchers noted a mixture of dust and pollen, along with sodium chloride (NaCl) and some magnesium sulfate (MgSO4) on the surface of the canisters. Sodium chloride can cause corrosion in some metals, but it is unlikely given the environment the casks are in.. Using temperature and humidity data from the Vandenberg weather station, the time required for chloride induced stress corrosion cracking (CISCC) to corrode through the cask would be greater than 1,800 years. NRC staff will continue to monitor the situation to ensure such corrosion does not become a problem. Another CISCC-inducing compound, magnesium chloride (MgCl2), was not present on the Diablo Canyon canisters. The conclusion section of the SANDIA report explains limitations for the sample collection and analysis.

Additional information is available in the following EPRI and Sandia reports:
        - EPRI-3002002822
        - SAND2014-16383
        - Susceptibility Assessment Criteria for Chloride-Induced Stress Corrosion Cracking (CISCC) of Welded Stainless Steel Canisters for Dry Cask Storage Systems

 

## Questions and Answers – Spent Fuel Pool Safety

**What do you look at when you license a fuel storage facility? How do I know it can withstand a natural disaster?**

The NRC's requirements for both wet and dry storage can be found in Title 10 of the Code of Federal Regulations (10 CFR), including the general design criteria in Appendix A to Part 50 and the spent-fuel storage requirements in Part 72. The staff uses these rules to determine that the fuel will remain safe under anticipated operating and accident conditions. There are requirements on topics such as radiation shielding, heat removal, and criticality. In addition, the staff reviews fuel storage designs for protection against:
        - natural phenomena, such as seismic events, tornados, and flooding
        - dynamic effects, such as flying debris or drops from fuel handling equipment and drops of fuel storage and handling equipment
        - hazards to the storage site from nearby activities

**How do you know the fuel pools are safe? Does the NRC inspect these facilities, or just the reactor itself?**

NRC inspectors are responsible for verifying that spent fuel pools and related operations are consistent with a plant's license. For example, our staff inspects spent fuel pool operations during each refueling outage. We also performed specialized inspections to verify that new spent fuel cooling capabilities and operating practices were being implemented properly.

**What would happen to a spent fuel pool during an earthquake? How can I be sure the pool wouldn't be damaged?**

All spent fuel pools are designed to seismic standards consistent with other important safety-related structures on the site. The pool and its supporting systems are located within structures that protect against natural phenomena and flying debris. The pools' thick walls and floors provide structural integrity and further protection of the fuel from natural phenomena and debris. In addition, the deep water above the stored fuel (typically more than 20 feet above the top of the spent fuel rods) would absorb the energy of debris that could fall into the pool. Finally, the racks that support the fuel are designed to keep the fuel in its designed configuration after a seismic event.

**Can spent fuel pools leak?**

Spent fuel pools lined with stainless steel are designed to protect against a substantial loss of the water that cools the fuel. Pipes typically enter the pool above the level of the stored fuel, so that the fuel would stay covered even if there were a problem with one of the pipes. The only exceptions are small leakage-detection lines and, at two pressurized water reactor (PWR) sites, robust fuel transfer tubes that enter the spent fuel pool directly. The liner normally prevents water from being lost through the leak detection lines, and isolation valves or plugs are available if the liner experiences a large leak or tear.

**How would you know about a leak in such a large pool of water?**

The spent fuel pools associated with all but one operating reactor have liner leakage collection to allow detection of very small leaks. In addition, the spent fuel pool and fuel storage area have diverse instruments to alert operators to possible large losses of water, which could be indicated by low water level, high water temperature, or high radiation levels.

**How can operators get water back in the pool if there is a leak or a failure?**

All plants have systems available to replace water that could evaporate or leak from a spent fuel pool. Most plants have at least one system designed to be available following a design basis earthquake. In addition, the industry's experience indicates that systems not specifically designed to meet seismic criteria are likely to survive a design basis earthquake and be available to replenish water to the spent fuel pools. Furthermore, plant operators can use emergency and accident procedures that identify temporary systems to provide water to the spent fuel pool if normal systems are unavailable. In some cases, operators would need to connect hoses or install short pipes between systems. The fuel is unlikely to become uncovered rapidly because of the large water volume in the pool, the robust design of the pool structure, and the limited paths for loss of water from the pool.

**Do U.S. nuclear power plants store their fuel above grade? Why is this considered safe?**

For boiling water reactor (BWR) Mark I and II designs, the spent fuel pool structures are located in the reactor building at an elevation several stories above the ground (about 50 to 60 feet above ground for the Mark I reactors). The spent fuel pools at other operating reactors in the U.S. are typically located with the bottom of the pool at or below plant grade level. Regardless of the location of the pool, its robust construction provides the potential for the structure to withstand events well beyond those considered in the original design. In addition, there are multiple means of restoring water to the spent fuel pools in the unlikely event that any is lost.

**How are spent fuel pools kept cool? What happens if the cooling system fails?**

The spent fuel pool is cooled by an attached cooling system. The system keeps fuel temperatures low enough that, even if cooling were lost, operators would have substantial time to recover cooling before boiling could occur in the spent fuel pool. Licensees also have backup ways to cool the spent fuel pool, using temporary equipment that would be available even after fires, explosions, or other unlikely events that could damage large portions of the facility and prevent operation of normal cooling systems. Operators have been trained to use this backup equipment, and it has been evaluated to provide adequate cooling even if the pool structure loses its water-tight integrity.

**What keeps spent fuel from re-starting a nuclear chain reaction in the pool?**

Spent fuel pools are designed with appropriate space between fuel assemblies and neutron-absorbing plates attached to the storage rack between each fuel assembly. Under normal conditions, these design features mean that there is substantial margin to prevent criticality (i.e., a condition where nuclear fission would become self-sustaining). Calculations demonstrate that some margin to criticality is maintained for a variety of abnormal conditions, including fuel handling accidents involving a dropped fuel assembly.

## Questions and Answers – Dry Cask Safety

**What is dry cask storage?**

Dry cask storage allows spent fuel that has already been cooled in the spent fuel pool for several years to be surrounded by inert gas inside a container called a cask. The casks are typically steel cylinders that are either welded or bolted closed. The steel cylinder provides containment of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public.

**What is an "ISFSI"?**

An independent spent fuel storage installation, or ISFSI, is a facility that is designed and constructed for the interim storage of spent nuclear fuel. These facilities are licensed separately from a nuclear power plant and are considered independent even though they may be located on the site of another NRC-licensed facility.

**What kind of license is required for an ISFSI?**

NRC authorizes storage of spent nuclear fuel at an ISFSI in two ways: site-specific or general license. For site-specific applications, the NRC reviews the safety, environmental, physical security and financial aspects of the licensee and proposed ISFSI and, if we conclude it can operate safely, we issue a license. This license contains requirements on topics such as leak testing and monitoring and specifies the quantity and type of material the licensee is authorized to store at the site. A general license authorizes storage of spent fuel in casks previously approved by the NRC at a site already licensed to possess fuel to operate a nuclear power plant. Licensees must show the NRC that it is safe to store spent fuel in dry casks at their site, including analysis of earthquake intensity and tornado missiles. Licensees also review their programs (such as security or emergency planning) and make any changes needed to incorporate an ISFSI at their site. Of the currently licensed ISFSIs, 48 are operating under general licenses and 15 have specific licenses.

**How does the NRC determine that a dry storage system is safe?**

Before approving any dry storage system and issuing a Certificate of Compliance or a license, the NRC staff conducts a thorough engineering review to ensure the system design meets all necessary safety requirements. Dry storage systems must be designed to protect the public and workers from radiation exposure. In addition, dry storage systems must be able to withstand credible natural disasters and accidents. The NRC staff's dry storage system reviews are documented in safety evaluation reports, which are publicly available in the NRC Agencywide Documents Access and Management System (ADAMS). The NRC staff also conducts quality assurance inspections of vendors who design and manufacture the storage systems and operating spent fuel storage facilities to ensure compliance with the NRC's safety requirements.

For more information, see NUREG/BR-0528

**What are the requirements for the selection and use of a dry storage system at an NRC licensed commercial power reactor site?**

A licensee's selection of a dry cask storage system is based on the operational needs of a specific reactor site (A list of approved casks can be found in 10 CFR 72.214). A licensee must first determine whether a particular system addresses the storage site's parameters, including analyses of potential earthquake intensity and tornado missiles. A licensee must provide reasonable assurance that the location's conditions meet the necessary safety requirements for adequate protection. The evaluation requirements for a dry storage system user can be found in 10 CFR 72.212.

**What Risk Assessments have been conducted for dry storage systems?**The NRC and the Electrical Power Research Institute (EPRI) have performed risk assessments for dry storage systems. These analyses considered the release of radioactive gases and found the radiation doses to be below NRC's safety requirements. The NRC staff also evaluated a post-accident release of radioactive gases from breached storage canisters that contain damaged fuel assemblies. EPRI has also conducted a risk assessment regarding the radiological risks to the public during the life cycle of a bolted spent fuel cask. NUREG-1864 assesses a comprehensive list of initiating events, including dropping the cask during handling, and external events during onsite storage (such as earthquakes, floods, high winds, lightning strikes, accidental aircraft crashes, and pipeline explosions). All of these studies concluded that the risks of the public receiving a dose above regulatory limits is very low.

For more information, see the following:
        - NUREG-1864
        - EPRI Technical Report 1002877    

**How do the NRC requirements ensure that dry storage systems do not release radioactive material and expose workers and members of the public to radiation?**

The NRC requires dry storage systems to meet NRC safety requirements at all times, including during or after a design basis accident. A design basis accident is any event that could significantly affect the storage system. Accident conditions include events such as fuel rod rupture and air flow blockage, as well as natural phenomena like earthquakes, burial under debris, lightning strikes, and other phenomena (e.g., seiches, tsunamis, and hurricanes). Different accident conditions are evaluated as appropriate  depending on the storage cask's location. NRC requirements in 10 CFR 72.104 define annual dose limits for normal operations and anticipated events, while requirements in 10 CFR 72.106 define dose limits for a design basis accident. These dose limits do not pose a significant safety concern to workers or the public, and are a fraction of the average annual dose received from background radiation.

**How are dry storage systems inspected?**

Nondestructive examination (NDE) methods for the inspection of canisters already exist and have been used in the nuclear industry for decades. These NDE methods include visual testing (VT), Eddy current testing (ECT), and Ultrasonic testing (UT). ECT utilizes magnetic fields to identify cracks and defects. Similarly, UT utilizes sound waves as the method for detection. Together, the three methods can detect and characterize potential aging effects like localized corrosion. Methods to apply existing NDE techniques to stainless steel canisters have been developed, and currently are being tested by both the Electrical Power Research Institute (EPRI) and dry storage system manufacturers.

Additional information is available in the following EPRI reports:
        - EPRI-3002008234
        - EPRI-3002010617
        - EPRI-3002010621

 

**What can remote visual testing be used to detect?**

Remote visual testing (RVT) is a nondestructive way to detect cracking, corrosion, wear and component failures. The ability of RVT methods to detect cracking was reviewed and documented in NUREG/CR-7246. Crack size was found to be an important feature that limits the detection of cracks by RVT. Very small cracks are harder to detect using RVT. Detection by RVT is also challenged when cracks are located in the proximity of surface features, such as grinding marks or weld ripples. RVT is still a viable inspection method despite its limitations. Because the detection of CISCC cracks on canisters using RVT could be challenging, the example aging management programs developed by NRC staff and aging management guidance developed by the Electrical Power Research Institute (EPRI) have relied on indications of localized corrosion, such as pitting, that can be reliably detected using visual testing methods.

For more information, see the following:
        - NUREG/CR-7246
        - NUREG-2214
        - EPRI-3002008193

**How does the NRC conduct oversight of Licensees?**

Licensees are responsible for operating their facilities safely. The NRC verifies licensees' compliance with safety regulations through its inspection program. This includes inspections of operating facilities and cask vendors. The frequency of these inspections is based on the licensee's performance and the presence of activity (cask loadings, extreme weather conditions, etc.). The NRC requires prompt corrective action by the licensee if a safety problem or failure to comply with requirements is discovered. Enforcement action may follow depending on the severity of the inspection findings.

For more information on how specifically inspections are done, see the NRC Inspection Manual, Manual Chapter 2690

**How does the NRC verify that canisters are properly loaded in accordance with their NRC Certificate of Compliance?**

Before the licensee has loaded a single canister, the NRC inspects the licensee's spent fuel loading procedures by observing and assessing the implementation of those procedures during a "dry run" rehearsal before actual loading is performed. The NRC also observes the initial cask loading. This means the very first cask loaded by a licensee is always observed. NRC inspectors generally observe and review licensee's identification, parameters, and characteristics of each fuel assembly. Verification is also performed through review of procedures that lead to the selection and verification of fuel assemblies prior to each loading. After the first loading has been observed, inspectors will periodically observe future cask loadings to ensure canisters are still being properly loaded. If a misloading is identified the licensee must immediately conduct an evaluation to show the NRC the loading still meets the acceptance criteria. In no misloading case has there ever been a safety concern.

**How can the fuel or internal components be inspected on canisters with welded lids?**

At this time there are no methods available for inspecting the internal components of welded stainless steel canisters once they are loaded. Several measures are taken during the loading process to ensure there will be no need to re-open a welded canister. Each canister is leak tested prior to use to ensure the inert helium environment will remain inside the canister. The inert environment prevents the stored spent fuel from degrading and eliminates the need to inspect the fuel or the interior of the canister. If there is a safety need to open a welded canister, there is a procedure approved by NRC staff in the dry storage system's safety analysis report.

**How would welded stainless steel canisters be repaired if necessary?**

In the unlikely event that a canister repair would be needed, corrective actions would be performed on a case-specific basis for the affected dry storage system component. Corrective actions may be proposed to mitigate an identified degradation before the canister integrity is compromised, or to bring a canister back into compliance if the degradation has compromised the canister integrity. The licensee would propose corrective actions to the NRC in either case, and NRC staff would evaluate whether the corrective actions are sufficient to preserve the intended safety functions of the dry storage system and maintain compliance with the regulations of 10 CFR Part 72. Proposed repair methods also require demonstration and compliance with an NRC-approved quality assurance program.

## Questions and Answers – Waste Confidence & Future Plans

**How long is spent fuel allowed to be stored in a pool or cask?**

NRC regulations do not specify a maximum time for storing spent fuel in pool or cask. The agency's “waste confidence decision" expresses the Commission's confidence that the fuel can be stored safely in either pool or cask for at least 60 years beyond the licensed life of any reactor without significant environmental effects. At current licensing terms (40 years of initial reactor operation plus 20 of extended operation), that would amount to at least 120 years of safe storage.

However, it is important to note that this does not mean NRC "allows" or "permits" storage for that period. Dry casks are licensed or certified for up to 40 years, with possible renewals of up to 40 years. This shorter licensing term means the casks are reviewed and inspected, and the NRC ensures the licensee has an adequate aging management program to maintain the facility.

**What is the plan for storage of spent nuclear fuel going forward? Will on-site storage continue to be the way for the foreseeable future?**

The U.S. policy for nuclear waste management, as set forth in the Nuclear Waste Policy Act, is for permanent disposal of spent fuel in a deep underground geological repository. Decades of scientific research supports the use of a repository for disposal of spent fuel. Federal responsibility for siting and building a repository remains national policy. The NRC acknowledges the challenges encountered over the years in siting and licensing the proposed repository at Yucca Mountain. The Commission remains confident that a repository will be built. The Commission does not consider that accumulated spent fuel will be stored permanently at current or former reactor sites and does not endorse permanent storage at reactor sites.

Although the NRC considers that 25 to 35 years is a reasonable timeframe for repository development, it acknowledges that there is sufficient uncertainty in this estimate that the possibility that more time will be needed cannot be ruled out. International and domestic experience have made it clear that technical knowledge and experience alone are not sufficient to bring about the broad social and political acceptance needed to construct a repository. The time needed to develop a societal and political consensus for a repository could add to the time to site and license a repository, or overlap it to some degree.

**These casks are already pretty old and could be storing spent fuel for decades to come. How can you protect them from deteriorating over time, especially from effects that have been seen at other nuclear installations such as alkali-silica reaction or chloride-induced stress corrosion cracking?**

Dry cask storage systems have been used at U.S. nuclear power plants for more than 30 years with an excellent safety record. Part of the reason for that success is the robust design of the systems. Another reason is proper care and maintenance, including implementation of aging management programs (AMPs) required by the NRC.The NRC conducted an extensive review of the materials used in dry cask storage systems, looking at how these materials might degrade over time. This review was documented in NUREG-2214. The NRC reviewed specific dry cask storage system designs, and the environments in which the systems operate. The report describes the scientific methods used to determine the likely effects of aging on the storage systems, and what might cause those effects. It also includes examples of generic AMPs licensees may use to develop their own programs. Additional guidance on aging management for dry storage systems was published in NUREG-1927. NRC inspectors examine a licensee's AMPs to verify that any potential degradation is quickly identified, and corrective actions taken to ensure the storage cask continues to function properly.

Two ways dry storage systems could possibly degrade over time are alkali-silica reaction (ASR) on concrete, and chloride-induced stress corrosion cracking (CISCC) of welded stainless steel canisters. No ASR has been reported on a dry storage system to date, though it is something licensees must include in their AMPs. NRC staff research on CISCC concluded that the risk is not credible during the first 20 years of operation because of the long time needed for cracks to grow through the stainless steel canister wall. After 20 years, CISCC is covered by the AMP. The Electrical Power Research Institute (EPRI) has also conducted a thorough assessment of the potential for CISCC in dry storage system canisters.

**How are the long-term impacts of onsite storage of spent fuel analyzed, and what measures are taken to minimize potential impacts on public health and safety?**

All storage systems approved by the NRC have been reviewed to ensure they meet all the regulatory safety requirements. These requirements address the credible hazards from natural disasters and accidents that the spent fuel storage systems may encounter. Long term, the NRC requires dry storage system users to have Aging Management Programs (AMPs) to ensure safety.  NUREG-1927 and NUREG-2214 provide more detailed information about aging management activities for dry storage systems. These guidance documents will continue to be updated as necessary.

NRC staff also conduct an environmental review of each independent spent fuel storage installation (ISFSI) to comply with the National Environmental Policy Act (NEPA). The NRC's NEPA requirements are in 10 CFR Part 51.  In 2014, NRC staff evaluated the environmental impacts of continued storage of spent fuel.  This evaluation is documented in NUREG-2157 and shows that the long-term storage of spent fuel has a low environmental impact.For more information, see the following:
        - NUREG-1927
        - NUREG-2214
        - NUREG-2157

**After a plant is decommissioned there will be no infrastructure to handle the repackaging of spent fuel if the storage systems need replacement.  Is there a plan for this contingency, and what are the safety implications of reopening the storage cask?**

Storage casks should not be opened unless there is a specific safety need. Most welded stainless steel canisters are designed to be transportable inside a specifically designed transportation overpack.  This allows fuel to be transported without directly handling the fuel.  The canisters are leak tested and this assures that the helium environment will be maintained inside the canister.  A helium environment is important because helium is an inert gas, meaning it does not undergo chemical reactions. If safety issues are identified, it is the responsibility of the licensee to propose corrective actions, and the NRC's responsibility to ensure these actions maintain the safety functions of the storage system. Each specific dry storage system has specific procedures for opening the canister outlined in the dry storage system or the independent spent fuel storage installation (ISFSI) safety analysis report. These procedures are reviewed by NRC staff.

## Questions and Answers – Security

**What about security? How do you know terrorists won't use all of this waste against us?**

For spent fuel, as with reactors, the NRC sets security requirements and licensees are responsible for providing the protection. We constantly remain aware of the capabilities of potential adversaries and threats to facilities, material, and activities, and we focus on physically protecting and controlling spent fuel to prevent sabotage, theft, and diversion. Some key features of these protection programs include intrusion detection, assessment of alarms, response to intrusions, and offsite assistance when necessary. Over the last 20 years, there have been no radiation releases that have affected the public. There have also been no known or suspected attempts to sabotage spent fuel casks or storage facilities. The NRC responded to the terrorist attacks on September 11, 2001, by promptly requiring security enhancements for spent fuel storage, both in spent fuel pools and dry casks.

**How are dry storage systems canisters at ISFSIs protected against terrorism such as the September 11, 2001 terrorist attacks using hijacked airplanes?**

The best defense against hijacked airplanes is airport security, enforced by the Department of Homeland Security's (DHS) Transportation Safety Administration. DHS, the U.S. military, and the intelligence community are responsible for the defense of the country. The NRC regularly works with these agencies to assess the threat environment, and is always ready to alert its licensees if a specific, credible threat is identified.

Security requirements at NRC-licensed facilities are based on the potential threat level and the potential consequences of an event. The NRC details the security requirements for physical protection of spent fuel storage in 10 CFR Part 73 and 10 CFR Part 72. Further orders also provide additional security measures.  Protection from, and responses to, security-related events are addressed in the licensee's NRC-approved Physical Security Plan, which is not publicly available. An independent spent fuel storage installation (ISFSI) licensee must comply with the security requirements which are implemented in their approved Physical Security Plan.

Over the past 20 years, there have been no known or suspected attempts to sabotage, or steal radioactive material from storage casks at ISFSIs, or to directly attack an ISFSI. Nevertheless, the NRC is continually evaluating threats to stay best prepared. Licensees are routinely inspected to ensure they are following their NRC-approved Physical Security Plan. NRC staff have conducted security assessments for ISFSIs using several storage cask designs that were representative of most currently certified designs. The resulting assessments formed the basis for the NRC's conclusion that there was no need for further security measures at ISFSIs beyond those currently required.

For more information, see Frequently Asked Questions About Security Assessments at Nuclear Power Plants.

## Questions and Answers – Emergency Planning

**Are potential seismic effects considered in the assessment of canisters for continued operation? –EP**

Yes, approved canister designs used at a specific independent spent fuel storage installation (ISFSI) location address the credible seismic hazards of that location. The canisters must maintain containment of the spent fuel under the predicted seismic loads for each location. In addition, the radiation exposure limits, thermal limits, confinement barrier integrity, structural performance, and nuclear criticality safety must be maintained. These requirements continue throughout the life of the dry storage systems and are maintained and verified by aging management activities and inspections.

**What are the emergency plans for nuclear waste at an ISFSI in the case of mishandling, leaks, natural disasters or acts of terrorisms?**An emergency plan for an independent spent fuel storage installation (ISFSI) is required by 10 CFR 72.32(c). The emergency plan identifies the actions to be taken to address a release and make the consequences less severe, regardless of the event. However, there is no credible accident scenario involving dry cask storage that would result in widespread consequences outside the facility boundary. That's because unlike operating power reactors, dry cask storage systems do not have the thermal or kinetic energy to spread radioactive contamination over a large area in the highly unlikely event a storage canister is breached. Emergency plans for ISFSIs are publicly available in ADAMS. Protection from and responses to security-related events are addressed in a licensee's NRC-approved Physical Security Plan, which are not publicly available.

For more information, see Frequently Asked Questions About Emergency Preparedness and Response.

**What emergency plans are required for spent fuel storage facilities at nuclear power plants undergoing decommissioning or sites that have completed decommissioning?**

Decommissioning reactors continue to be subject to the NRC's emergency planning requirements. For some period of time after the licensee ceases reactor operations, offsite emergency planning will be maintained. This period of time depends on when the reactor was last critical as well as site-specific considerations. Offsite emergency planning may be eliminated when the fuel has been removed from the reactor and placed in the spent fuel pool, and sufficient time has elapsed, such that there are no longer any postulated accidents that would result in offsite dose consequences large enough to require offsite emergency planning. There would be no requirement to maintain offsite systems to warn the public. Onsite emergency plans will be required for both the spent fuel pool and the Independent Spent Fuel Storage Installations, but offsite plans will not be required. If, however, an operating plant is located at the same site as the decommissioning plant, the emergency preparedness plans will still be in effect for the operating plant.

Although offsite emergency planning at a decommissioned site may no longer be required, licensees maintain offsite contacts since any emergency declaration requires notification of state and local officials as well as the NRC. In addition, due to the typically reduced staffs at a decommissioning facility they may rely even more on offsite assistance for fire, security, medical or other emergencies. These reduced EP requirements would remain in effect as long as fuel is onsite.

*(Note: This general description also applies to emergency planning for specifically licensed ISFSIs; those requirements are spelled out in detail in 10 CFR 72.32.)*

Page Last Reviewed/Updated Monday, February 07, 2022