All publicly available OIG reports (including this report) 

are accessible through NRC’s Web site at

http://www.nrc.gov/reading-rm/doc-collections/insp-gen

Audit of NRC’s

Oversight of Spent Fuel 

Pools 

OIG-15-A-06 

February 10, 2015 
UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555-0001

OFFICE OF THE

INSPECTOR GENERAL

February 10, 2015

MEMORANDUM TO: Mark A. Satorius

Executive Director for Operations

FROM: Stephen D. Dingbaum /RA/

Assistant Inspector General for Audits

SUBJECT: AUDIT OF NRC’S OVERSIGHT OF SPENT FUEL POOLS

(OIG-15-A-06)

Attached is the Office of the Inspector General’s (OIG) audit report titled Audit of NRC’s 

Oversight of Spent Fuel Pools.

The report presents the results of the subject audit. Following the January 22, 2015, exit 

conference, agency staff indicated that they had no formal comments for inclusion in this 

report.

Please provide information on actions taken or planned on each of the recommendations 

within 30 days of the date of this memorandum. Actions taken or planned are subject to OIG 

followup as stated in Management Directive 6.1.

We appreciate the cooperation extended to us by members of your staff during the audit. If 

you have any questions or comments about our report, please contact me at (301) 415-5915 

or Sherri Miotla, Team Leader, at (301) 415-5914.

Attachment: As stated
i

What We Found

NRC provides adequate oversight of spent fuel pools and the fuel they 

contain to protect public health and safety and the environment; however, 

opportunities exist for improvement. Specifically, we found that 

regulatory uncertainty exists in NRC’s evaluation of spent fuel pool 

criticality safety analyses. In addition, there are gaps in NRC’s spent fuel 

pool inspection program as inspections of spent fuel pools greatly vary 

between licensee sites and are limited in scope. 

To fulfill its responsibility to protect public health and safety, NRC must 

inspect and assess licensee operations and facilities to ensure compliance 

with its regulatory requirements. NRC should also regulate in a manner 

that clearly communicates requirements and ensures that regulations are 

consistently applied and are practical. An absence of effective spent fuel 

pool criticality analyses guidance for both licensees and NRC staff may lead 

to a reduction in program efficiency and effectiveness. As a result of spent 

fuel pools not being inspected with regularity, they could potentially be 

overlooked.

What We Recommend

To improve the agency’s oversight of spent fuel pools, we make 

recommendations to provide a generic regulatory solution for spent fuel 

pool criticality analysis by developing and issuing detailed licensee 

guidance along with NRC internal procedures; develop and implement 

spent fuel pool inspection guidance at operating reactors; develop an 

enforceable neutron-absorbing material aging management program; 

update Inspection Manual Chapter 2561 and Inspection Procedure 60801. 

Management stated their general agreement with the findings and 

recommendations in this report. 

Office of the Inspector General

U.S. Nuclear Regulatory Commission

Defense Nuclear Facilities Safety Board

Results in Brief

Audit of NRC’s Oversight of Spent Fuel Pools Why We Did This Review

The Nuclear Regulatory 

Commission (NRC) is 

responsible for developing the

regulatory framework, analytical 

tools, and data needed to ensure 

safe and secure storage, 

transportation, and disposal of 

spent nuclear fuel. For both 

operating and permanently 

shutdown nuclear power plants 

in the United States, there are a 

total of 93 spent fuel pools that 

currently store spent fuel. 

Recent NRC staff studies 

demonstrating the safety of 

spent fuel pools and the safety of 

continued storage of spent fuel 

at reactor sites highlight the 

need to ensure the safety of pool 

operations for longer periods 

than originally envisioned. 

The audit objective was to 

determine whether NRC’s 

oversight of spent fuel pools and 

the nuclear fuel they contain 

provides adequate protection for 

public health and safety, and the 

environment. 

OIG-15-A-06

February 10, 2015
Audit of NRC’s Oversight of Spent Fuel Pools

i

ABBREVIATIONS AND ACRONYNMS........................................................ i

I. BACKGROUND ................................................................................1

II. OBJECTIVE......................................................................................6

III. FINDINGS.........................................................................................6

A. Regulatory Uncertainty Exists Over Spent Fuel Pool 

Criticality Analyses ................................................................7

Recommendation.................................................................14

B. NRC’s Spent Fuel Pool Inspection Program Could Be 

Enhanced ............................................................................15

Recommendations ...............................................................21

IV. CONSOLIDATED LIST OF RECOMMENDATIONS.......................23

V. AGENCY COMMENTS...................................................................24

APPENDIXES 

A. OBJECTIVE, SCOPE, AND METHODOLODY...............................25

TO REPORT FRAUD, WASTE, OR ABUSE.............................................28

COMMENTS AND SUGGESTIONS..........................................................28

 TABLE OF CONTENTS
Audit of NRC’s Oversight of Spent Fuel Pools

i

 ABBREVIATIONS AND ACRONYMS

10 CFR Title 10 of the Code of Federal Regulations

EA Enforcement Action

NRC U.S. Nuclear Regulatory Commission

NRR Office of Nuclear Reactor Regulation

OIG Office of the Inspector General

RAI Request for Additional Information

ROP Reactor Oversight Process 
Audit of NRC’s Oversight of Spent Fuel Pools

1

Spent fuel pools are deep pools of water that hold thermally hot and 

intensely radioactive spent (used) nuclear fuel after its removal from a 

nuclear reactor. The water in the spent fuel pools acts as a shield to 

reduce the radiation levels that people working outside the pool may be 

exposed to, and it also cools the spent fuel that continues to produce heat 

for several years after removal from the reactor. See Figure 1 for a photo 

of a spent fuel pool.

Figure 1: Spent Fuel Pool

Source: Nuclear Regulatory Commission (NRC).

Spent fuel pools are typically 40 or more feet deep, with at least 20 feet of 

water covering the spent fuel, to provide safety and allow fuel assemblies1

to be moved while submerged. The walls of the pools are typically 4- to 6-

feet thick with steel-reinforced concrete and a steel liner. The pools must 

be located inside what is known as the vital area of a nuclear power 

reactor, protected by armed guards, physical barriers, and limited access. 

 1 Spent fuel comes in the form of small pellets that are fitted into 12- to 15-foot hollow metal rods made of 

a zirconium alloy. These rods are then bound together into a larger “fuel assembly.” Typical fuel 

assemblies for boiling water reactors hold 49 to 63 fuel rods, and for pressurized water reactors hold 164 

to 264 fuel rods.

 I. BACKGROUND
Audit of NRC’s Oversight of Spent Fuel Pools

2

For both operating and permanently shutdown nuclear power plants in the 

United States, there are a total of 93 spent fuel pools2 that currently store 

spent fuel. See Figure 2. 

Figure 2: Total Number of Spent Fuel Pools Containing Fuel 

(Including Those at Shutdown Power Plants3

)

 2 There is also a spent fuel pool at GE Morris in Illinois. While it contains spent fuel, it is not associated 

with any nuclear power plant and is licensed under 10 CFR Part 72.

3 The number of spent fuel pools at each power plant is represented by the parenthetical number 

following the name of the plant. 

Arkansas 

Nuclear 

One (2)

Beaver 

Valley (2)

Browns 

Ferry (3)

Brunswick (2)

Byron (1)

Callaway (1)

Calvert Cliffs (1)

Catawba (2)

Columbia (1)

Comanche Peak (1)

Cooper (1)

Davis 

Besse (1)

Diablo Canyon (2)

Dresden (1)

Hatch (2)

Fermi (1)

Grand 

Gulf (1)

Fort 

Calhoun (1)

HB Robinson (1)

Hope Creek (1) & 

Salem (2)

Braidwood (1)

Clinton (1)

Indian Point (2)

Farley (2)

Kewaunee (1) Limerick (2)

McGuire (2)

Millstone (2)

North Anna (1)

Oconee (2)

Oyster Creek (1)

 DC 

Cook (1)

Palisades (1)

Palo 

Verde (3)

Peach Bottom (2)

Perry (1)

Pilgrim (1)

Point Beach (1)

Duane 

Arnold (1)

Prairie Island (1)

Quad La Salle (2)

Cities (2)

River 

Bend (1)

St. Lucie (2)

San Onofre (2)

Seabrook (1)

Sequoyah (1)

Shearon Harris (1)

South Texas 

Project (2)

Surry (1)

Susquehanna (2)

Three Mile 

Island (1)

Ginna (1)

Fitzpatrick (1)

Nine 

Mile 

Point (2)

Turkey Point (2)

Vermont 

Yankee (1)

V.C. Summer (1)

Vogtle (2)

Waterford 

(1)

Watts Bar (1)

Wolf Creek (1)

Monticello (1)

Spent Fuel Pool

Zion (1)

Crystal River (1)

Source: OIG.
Audit of NRC’s Oversight of Spent Fuel Pools

3

NRC Oversight

10 CFR 50

The governing NRC regulation for spent fuel pools is Title 10 of the Code 

of Federal Regulations (10 CFR), Part 50. This regulation provides for the 

domestic licensing of production and utilization facilities. Some of the 

sections within the regulation that specify spent fuel include conditions of 

licenses, requirements for monitoring maintenance effectiveness at 

nuclear power plants, and criticality4 accident requirements. The 

regulation also contains general design criteria that establish the 

requirements for fuel storage and handling, monitoring fuel and waste 

storage, and prevention of criticality in fuel storage. 

Post-Fukushima Orders5

In response to the events at Fukushima,6 NRC determined that additional 

requirements must be imposed to mitigate beyond-design-basis7 external 

events. Therefore, the agency created two new orders related to spent 

fuel pools: EA-12-049 and EA-12-051. 

The requirements in EA-12-049 provide for mitigation strategies to be 

available in the event of a power loss. This order requires using installed 

equipment and resources to maintain or restore core cooling, containment, 

and spent fuel pool cooling; providing sufficient, portable, onsite 

 4 Criticality is the condition in which each fission event releases a sufficient number of neutrons to sustain 

an ongoing series of reactions (i.e., a self-sustaining nuclear chain reaction). NRC’s goal is to prevent 

any inadvertent criticalities in spent fuel pools. 

5 Safety orders, typically imposing new requirements beyond the current existing regulatory framework, 

may be imposed in unusual circumstances to provide reasonable assurance of public health and safety. 

6 On March 11, 2011, a 9.0-magnitude earthquake and an estimated 45-foot-high tsunami struck Japan 

off the Honshu Island coast at the Fukushima Dai-ichi nuclear power plant, causing a hydrogen explosion 

and release of radioactive material. Radioactive contamination spread over a large area of Japan, 

requiring the relocation of tens of thousands of people. 

7 “Beyond-design-basis” accidents is a term used as a technical way to discuss accident sequences that 

are possible but were not fully considered in the design process because they were judged to be too 

unlikely. As the regulatory process strives to be as thorough as possible, beyond-design-basis accident 

sequences are analyzed to fully understand the capability of a design.
Audit of NRC’s Oversight of Spent Fuel Pools

4

equipment and consumables to maintain or restore these functions; and 

obtaining sufficient offsite resources to sustain those functions indefinitely. 

The requirements in EA-12-051 mandate that all power reactor licensees 

and construction permit holders have a reliable means of remotely 

monitoring spent fuel pool levels. 

The intent of these additional requirements is to provide a substantial 

increase in the protection of public health and safety. NRC is to begin 

inspecting licensee implementation in 2015.

NRC Program Offices

Several NRC headquarters program offices (as well as the regional 

offices) have involvement with spent fuel pools, but the primary office 

responsible for spent fuel pool oversight is the Office of Nuclear Reactor 

Regulation (NRR). NRR is responsible for the licensing and regulation of 

nuclear power reactors. This program office is also responsible for

overseeing licensee activities that protect the health and safety of workers 

and the general public from radiation hazards, including those from high 

level waste such as spent fuel. Within NRR, the Division of Safety 

Systems is responsible for 10 CFR Part 50 licensing of existing reactors. 

The Division of Operating Reactor Licensing implements the policy, 

programs, and activities, including coordinating licensing and technical 

reviews, associated with the overall safety for operating power reactors. 

Finally, the Division of Inspection and Regional Support provides 

inspection support for the regions and performance assessment related to 

the Reactor Oversight Process.

Recent NRC Initiatives Regarding Spent Fuel Pools 

Spent Fuel Pool Study

Although the spent fuel pools and the spent fuel assemblies stored in the 

pools remained intact after the disaster at the Fukushima Dai-ichi nuclear 

power plant, the event led to questions about the safe storage of spent 
Audit of NRC’s Oversight of Spent Fuel Pools

5

fuel and whether NRC should require expedited transfer of spent fuel from 

pools to dry cask storage at U.S. nuclear power plants. This prompted 

NRC to conduct a study to help determine if accelerated transfer of spent 

fuel from the spent fuel pool to dry cask storage significantly reduces risks 

to public health and safety.

In October 2013, NRC published the results of its study. The study stated 

that the analysis was consistent with earlier research conclusions that 

spent fuel pools are robust structures that are likely to withstand severe 

earthquakes without leaking. The study estimated that the likelihood of a 

radiological release from the spent fuel pool resulting from the selected 

severe seismic event analyzed was on the order of one time in 10 million 

years or lower. Therefore, NRC concluded that expediting movement of 

spent fuel from the pool to dry casks does not provide a substantial safety 

enhancement, and that spent fuel pools provide adequate protection of 

public health and safety.

Other Initiatives

In addition to the spent fuel pool study, NRC has taken on other recent 

initiatives to address spent fuel pools. For example, NRC has been 

working closely with the nuclear industry over the past 2 years to develop 

improved criticality safety guidance. The guidance is currently in draft

mode. NRC is also in the process of updating guidance documents for 

shutdown nuclear power plants. Additionally, NRC is currently preparing a 

Generic Letter on neutron-absorbing materials.8

 The intent of the Generic 

Letter is to seek more information from licensees about their neutron 

absorbers and determine whether further regulatory action is required to 

ensure compliance with NRC regulations. 

 8 Neutron-absorbing materials, such as Boraflex, Boral, and Carborundum, are placed between fuel 

assemblies allowing for the safe storage of fuel in close proximity to one another. The purpose of the 

neutron absorber materials is to ensure criticality does not occur in any spent fuel pool fuel assemblies. 

Some of the neutron absorber materials have experienced various levels of degradation in the form of 

blisters as well as general corrosion which, in some instances, has had an impact on criticality safety.
Audit of NRC’s Oversight of Spent Fuel Pools

6

The audit objective was to determine whether NRC’s oversight of spent 

fuel pools and the nuclear fuel they contain provides adequate protection 

for public health and safety, and the environment. Appendix A of this 

report contains information on the audit’s scope and methodology.

NRC provides adequate oversight of spent fuel pools and the nuclear fuel 

they contain to protect public health and safety and the environment; 

however, opportunities exist for improvement. Recent NRC staff studies 

demonstrating the safety of spent fuel pools and the safety of continued 

storage of spent fuel at reactor sites highlight the need to ensure the 

safety of pool operations for longer periods than originally envisioned. To 

accomplish this, NRC’s spent fuel pool oversight would be more effective 

for the long term with additional guidance for NRC staff and licensees in 

the following areas: 

• Improved criticality analyses guidance and reviews to enhance the

clarity and predictability of NRC’s licensing process related to spent 

fuel pools.

• Enhanced reactor oversight process inspection guidance to call 

attention to spent fuel pools and their related systems.

 II. OBJECTIVE

 III. FINDINGS
Audit of NRC’s Oversight of Spent Fuel Pools

7

A. Regulatory Uncertainty Exists Over Spent Fuel Pool 

Criticality Analyses

Regulatory uncertainty exists in NRC’s evaluation of spent fuel pool 

criticality safety analyses. NRC should regulate in a manner that clearly 

communicates requirements and ensures that regulations are consistently 

applied and are practical. However, there is an absence of effective spent 

fuel pool criticality analyses guidance for both licensees and NRC staff.

This could lead to a reduction in program efficiency and effectiveness. 

NRC Should Clearly Communicate Requirements

According to NRC’s Strategic Plan, Fiscal Years 2014-2018,9 the agency 

should maintain stable and predictable regulatory programs and policies.

NRC should apply regulatory tools consistently across and within agency 

program areas, and regulate in a manner that clearly communicates 

requirements and ensures that regulations are practical and consistently 

applied. In addition, NRC should conduct quality reviews of licensing 

requests and issue timely decisions consistent with agency performance 

indicators. The Strategic Plan also highlights that NRC’s vision is to be a 

transparent and effective nuclear regulator.

NRC’s Principles of Good Regulation states that regulations should be 

coherent, logical, and practical. There should be a clear nexus between 

regulations and agency goals and objectives. Agency positions should be 

readily understood and easily applied. Moreover, regulatory decisions 

should be made without undue delay.

 9 NUREG-1614, Vol. 6, published August 2014.

What Is Required
Audit of NRC’s Oversight of Spent Fuel Pools

8

Regulatory Uncertainty Over Spent Fuel Pool Criticality Analyses

Whenever licensees make a major change to their plant that could affect 

the spent fuel pool, such as a high density rerack10 or a change to their 

nuclear fuel design, they must go through NRC’s license amendment 

process before the change can be implemented. As part of this license 

amendment process, licensees must conduct new criticality safety 

analyses11 to ensure that the changes made to the pool do not affect the 

pool’s existing subcritical status.

12 NRC then must review and approve 

these criticality analyses prior to the license amendment’s final approval. 

There is regulatory uncertainty over the spent fuel pool criticality safety 

analyses. Licensees submit their criticality analyses to NRC for review but 

often the analyses are inadequate or insufficient according to NRC. NRC 

typically responds to criticality analysis submissions by sending licensees 

large numbers of requests for additional information (RAI). A licensee 

likened the RAI process to a “fishing expedition,” noting that it required a 

lot of resources and research with little instruction on how to address the 

questions. 

According to an industry representative, licensees do not always know 

what to expect when they submit a criticality analysis for review as part of 

a license amendment application as there is no consistency in NRC’s 

reviews. Another industry representative stated that the success of a 

license amendment application was a "crapshoot" depending on which 

NRC reviewer was assigned to the application. Yet another 

 10 Nuclear power plants rerack their spent fuel pools to allow for the storage of larger numbers of fuel 

assemblies. To remedy the situation of limited storage capacity, “high density” spent fuel storage racks 

were introduced. As the inventory of spent fuel has grown, reactor operators have increased the number 

of assemblies stored in the pools by replacing existing storage racks with newer racks holding denser 

arrangements of fuel assemblies.

11 Criticality analyses are complex analytical methods and calculations performed to determine that 

proper margin exists to maintain spent fuel pool subcriticality.

12Subcriticality is the condition of a nuclear reactor system in which nuclear fuel no longer sustains a 

fission chain reaction. Subcriticality is the desired state of all spent fuel pools.

What We Found
Audit of NRC’s Oversight of Spent Fuel Pools

9

representative said that licensees did not have confidence that NRC could 

do the necessary analyses and that licensees did not want to submit 

license amendment requests.

Compounding the issue is the amount of time it might take NRC to do the 

criticality reviews. One licensee explained the process and said it 

generally took his utility approximately 6 months to complete the initial 

criticality analysis. NRC would then take anywhere from 6 to 12 months to 

respond with its initial RAIs. The licensee said it would take about 1 

month to answer the RAIs, and then he would wait to hear from NRC 

again. This process would continue until the licensee sufficiently 

answered all the RAIs, possibly taking up to 3 years before the criticality 

analysis was approved and the license amendment granted. 

NRR staff provided data on all license amendment requests related to 

spent fuel pool criticality analyses covering the past 5 years through 

October 2014. See Table 1 for NRR timeliness statistics on license 

amendment requests involving spent fuel pool criticality reviews.

Table 1: License Amendment Request Timeliness Table

NRC Review Time License 

Amendment 

Requests 

Completed

License 

Amendment 

Requests 

Withdrawn

License 

Amendment 

Requests 

Currently Under 

Review

≤ 1 year 6 4 5

> 1 year & ≤ 2 years 20 10 3

> 2 years & ≤ 3 years 6 0 0

Source: Table generated by OIG from NRR data.
Audit of NRC’s Oversight of Spent Fuel Pools

10

Out of 54 eligible submitted applications, NRC completed only 6 reviews 

within 1 year. According to NRC’s Fiscal Year 2015 Congressional 

Budget Justification,

13 the agency’s timeliness metrics for license 

amendment requests should be at a 95-percent completion rate within 1 

year and a 100-percent completion rate within 2 years. An NRC senior 

manager acknowledged that these license amendment reviews “take a 

long time.” 

While the specific reasons for each of the 14 withdrawn license 

amendment requests above are not known, one licensee said his utility 

withdrew a couple of license amendment requests because of how long 

NRC’s reviews were taking. An industry representative also claimed that 

NRC review times averaged nearly 2 years and that license amendment

withdrawals had increased roughly 50 percent since the mid-2000s. 

At a nuclear power conference, a licensee claimed that one of its power 

plants had lost full core offload capability because it was behind schedule 

to rerack its spent fuel pool due to NRC’s license amendment request

process. The utility submitted a license amendment request, which was 

necessary for its spent fuel pool rerack. The representative said there 

were a significant number of NRC RAIs during the course of the next 13 

months that were issued a few at a time. He said the license amendment 

request was finally approved nearly 2 years after the initial submission, 

thereby delaying the fuel rerack by a year. He commented that, going 

forward, there would be no additional spent fuel pool criticality license 

amendment requests from his utility until NRC fixed its license amendment 

request timeliness issues. Conversely, regarding this specific incident, an 

NRC manager countered that the delays were caused by the utility doing a 

poor job with its criticality analysis.

Lack of Effective Guidance for Licensees and NRC

There is an absence of effective spent fuel pool criticality guidance for 

both licensees and NRC staff. 

 13 NUREG-1100, Volume 30, "FY2015 Congressional Budget Justification."

Why This Occurred
Audit of NRC’s Oversight of Spent Fuel Pools

11

Licensee Guidance

The primary spent fuel pool criticality guidance document available to 

licensees is the NRR Division of Safety Systems’ Interim Staff Guidance

2010-01, which was issued in 2010. This guidance document serves as a 

reference point for other criticality safety guidance documents. It was 

created to reiterate the existing guidance documents, clarify some of the 

ambiguity in the existing guidance documents, and identify lessons 

learned based on recent criticality submittals. However, licensee 

questions still remain as the guidance documents referenced by the 

interim staff guidance address only certain aspects of criticality safety and 

are not viewed by licensees as being descriptive enough.

For example, one licensee claimed that spent fuel pool criticality guidance 

contains a lot of open-ended statements and is subject to interpretation.

Another licensee opined that it would be great as an industry to reach a 

consensus on what a proper spent fuel pool criticality submittal should be.

Finally, an NRC senior manager stated that NRC could improve on how 

the agency interprets spent fuel pool criticality guidance into its policy —

“NRC should tell licensees what it accepts.”

Interim Staff Guidance and Regulatory Guides

Interim staff guidance may not be an appropriate form of licensee 

guidance. As the definition states,

Interim staff guidance documents are issued by an NRC office to 

clarify an aspect of the Standard Review Plan or to address issues 

not discussed in a Standard Review Plan.14 As suggested by its 

name, an interim staff guidance document serves as a placeholder 

guidance document until it is incorporated into the next revision of 

the applicable (permanent) guidance document. 

 14 A standard review plan contains guidance for NRC staff reviewers for performing safety reviews for 

applications to construct or operate nuclear power plants, or to obtain operating license amendments. It 

helps to ensure consistency of NRC staff reviews.
Audit of NRC’s Oversight of Spent Fuel Pools

12

By contrast, NRC has a regulatory guide when it comes to nuclear 

criticality safety for fuel and material facilities.

15 Per the definition,

Regulatory guides provide guidance for preparing a license 

application. They also describe acceptable methods for 

implementing NRC regulations, techniques used by the NRC staff 

in evaluating specific problems or postulated accidents, and data 

needed by NRC staff in its review of license applications and 

amendments. Regulatory guides are typically issued to define 

approaches acceptable to the NRC that licensees may take to 

comply with regulatory requirements. Regulatory guides may also 

provide sufficient information to help NRC staff perform its function. 

Based on the definitions of the two guidance documents above,16 it 

appears that a regulatory guide would be a more appropriate form of 

licensee guidance than interim staff guidance.

NRC Staff Guidance

Like licensees, NRC employees have insufficient criticality guidance. 

Currently, Interim Staff Guidance 2010-01 also serves as one of the 

primary guidance documents for NRC staff. In an OIG review of public 

meetings on spent fuel pool criticality safety between NRC and industry 

over the past 5 years, NRC stated on two separate occasions, “The [NRC] 

staff has found that a need exists to establish a consistent technical basis 

for validation of commercial spent nuclear fuel criticality safety 

evaluations.” An NRC senior manager said that the Standard Review 

Plan and other guidance that NRC had been reliant upon are outdated, 

and this is part of the reason why reviews have taken longer than 

expected.

A lack of effective internal guidance has created a dependency on 

individual or tribal17 knowledge because the spent fuel pool criticality team 

 15 Regulatory Guide 3.71, "Nuclear Criticality Safety Standards for Fuels and Material Facilities."

16 From NEI 07-06, “The Nuclear Regulatory Process.”
Audit of NRC’s Oversight of Spent Fuel Pools

13

in NRR is a very small group. According to an NRC manager, the group 

has often been understaffed over the years due to reassignments, staff 

departures, and extended absences. As a licensee said, “There is one 

reviewer who is very experienced, but the other reviewers seem to get 

switched out quite often, so there is a lot of educating in some cases.” 

Criticality analyses are very specialized and highly technical. There are

only a small number of NRC staff who are trained and qualified to conduct

this type of work. Likewise, licensees often lack the expertise to perform

these analyses internally and must hire contractors to do the work. In 

addition to lack of sufficient guidance, NRR management stated that the 

ever-increasing complexity of criticality reviews,

18 the large workload, and 

the lack of resources have contributed to the delays in approving license 

amendment requests. 

Decrease in Program Efficiency and Effectiveness

A lack of effective guidance could reduce program efficiency and 

effectiveness. An NRC senior manager claimed that licensees have 

expressed their desire to increase their use of NRC’s 50.59 change 

process19 to avoid what licensees perceive as NRC’s unpredictable review 

times and overly detailed RAIs concerning spent fuel pool criticality 

analyses. OIG performed a search on all 50.59 violations within the past 5 

fiscal years and found 4 instances where 50.59 violations occurred related 

to spent fuel pool criticality safety. While these particular violations do not 

necessarily indicate an intentional workaround by licensees, they do 

 17 Tribal knowledge refers to a set of unwritten rules or information that is known by a group of individuals 

within an organization but is not commonly known by others. This term is used most when referencing 

information that may need to be known by others in order to produce a quality product or service.

18 NRR management stated that criticality analyses are becoming more complex due to the increasing 

density of spent fuel stored in pools. This has led to licensee submissions that routinely challenge safety 

limits. Thus, more NRC review time and effort are needed to ensure licensees’ pools remain subcritical.

19 10 CFR 50.59 allows licensees to make certain procedure or facility changes without a license 

amendment provided that licensees meet specific requirements.

Why This Is Important
Audit of NRC’s Oversight of Spent Fuel Pools

14

illustrate that some licensees inappropriately used the 50.59 process 

related to criticality safety. With better guidance, these violations may be 

preventable as licensees should be able to submit higher quality criticality 

analyses and NRC should be able to decrease review times.

Program efficiency and effectiveness are also reduced when timeliness 

metrics are not achieved and licensees are unable to implement important 

changes to their spent fuel pools via the license amendment process. An 

industry representative stated that the regulatory uncertainty has been 

detrimental to safety as licensees have been “afraid” to apply for a license 

amendment; thus, licensees were afraid to make a change when the 

change may have improved spent fuel pool safety.

Improved guidance could provide better support for NRC’s succession 

planning and knowledge management efforts.

20 According to a senior 

NRC manager, if the current lead of the spent fuel pool criticality group 

were to leave NRC, there may not be a viable replacement readily 

available. This puts the agency in a very vulnerable position without 

proper effective guidance. NRR’s internal Web page states the 

importance of knowledge management – a loss of knowledge could 

challenge NRR in accomplishing its mission. Effective internal guidance 

addresses knowledge loss by reducing the reliance on any specific 

individual.

Recommendation

OIG recommends that the Executive Director for Operations

1. Provide a generic regulatory solution for spent fuel pool criticality 

analysis by developing and issuing detailed licensee guidance 

along with NRC internal procedures.

 20 Knowledge management entails capturing critical information and making the right information available 

to the right people at the right time.
Audit of NRC’s Oversight of Spent Fuel Pools

15

B. NRC’s Spent Fuel Pool Inspection Program Could Be 

Enhanced

There are gaps in NRC’s spent fuel pool inspection program as 

inspections of spent fuel pools greatly vary between licensee sites and are 

limited in scope. To fulfill its responsibility to protect public health and 

safety, NRC must inspect and assess licensee operations and facilities to 

ensure compliance with its regulatory requirements. However, variations

in spent fuel pool inspections result from guidance that is either outdated 

or virtually silent on spent fuel pools. Without improved guidance, spent 

fuel pools could potentially be overlooked. 

NRC Must Inspect and Assess Licensee Operations and Facilities

NRC’s responsibility and authority to inspect licensee facilities are both 

derived from the Atomic Energy Act of 1954, as amended, which provides 

the basis for the Commission to set standards and establish the rules for 

licensed activities and to inspect those activities. Inspections are intended 

to ensure that licensees meet NRC's regulatory requirements, 

demonstrating that they are most likely conducting safe operations that 

protect the public and the environment from any undue nuclear risk.

As stated in NRC’s Strategic Plan, Fiscal Years 2014-2018, to fulfill its 

responsibility to protect public health and safety, NRC must inspect and 

assess licensee operations and facilities to ensure compliance with its 

requirements. NRC should evaluate domestic operational experience 

associated with licensed facilities and activities. The agency must develop 

the regulatory framework, analytical tools, and data needed to ensure safe 

and secure storage, transportation, and disposal of spent nuclear fuel. 

NRC also must maintain effective and consistent oversight of licensee 

performance to drive continued licensee compliance with NRC safety 

requirements and license conditions.

What Is Required
Audit of NRC’s Oversight of Spent Fuel Pools

16

Resident inspector. Source: NRC.

What We Found

Spent Fuel Pool Inspection Oversight Varies Greatly Among

Licensed Facilities

There are gaps in NRC’s spent fuel pool inspection oversight as 

inspections of spent fuel pools greatly vary among licensee sites and are 

limited in scope. 

Spent Fuel Pool Inspections Based on Inspector Discretion

The Reactor Oversight Process (ROP) is the agency’s program to inspect, 

measure, and assess the safety and security performance of operating 

commercial nuclear power plants, including spent fuel pools. The ROP 

monitors plant performance in three key areas – reactor safety, radiation 

safety, and safeguards. 

However, within the ROP baseline program, there is no targeted safety 

inspection procedure for spent fuel pools.21 According to NRC 

guidance,

22 a separate spent fuel pool inspection procedure was not 

developed because the baseline inspection program is primarily based on 

the risk associated with reactor core 

damage when the reactor fuel is in the 

reactor vessel. Full-time resident 

inspectors and regional inspectors must 

complete baseline inspections and 

choose inspection areas using a riskinformed approach based on potential 

risk and past operational experience, as 

well as on regulatory requirements. 

Thus, inspections of spent fuel pools at operating reactors depend on the 

experience of the resident inspectors and the history of the plant. At their 

 21There is a required safety inspection that involves spent fuel pools, Inspection Procedure 71111.20, 

“Refueling and Other Outage Activities,” and a required security inspection involving spent fuel pools, 

Inspection Procedure 71130.11, “Material Control and Accounting.”

22 Inspection Manual Chapter 0308, Attachment 2, Technical Basis for Inspection Program.
Audit of NRC’s Oversight of Spent Fuel Pools

17

discretion, residents may include the spent fuel pools in samples selected 

for any of a number of procedures. Resident inspectors provided 

examples of inspection procedures with samples that could electively 

include an aspect of the spent fuel pool. These procedures are listed in 

Table 2.23

Table 2: Suggested Inspection Procedures for Spent Fuel Pools 

Inspection 

Procedure 

Number

Inspection Procedure Title

71111.04 Equipment Alignment

71111.12 Maintenance Effectiveness

71111.13 Maintenance Risk Assessments and 

Emergent Work Control

71111.15 Operability Determinations and 

Functionality Assessments

71111.18 Plant Modifications

71111.19 Post Maintenance Testing

71111.21 Component Design Bases Inspection

71111.22 Surveillance Testing

71152 Problem Identification and Resolution

Source: OIG generated based on resident inspector interviews.

Inspection Numbers Vary

Inspections of spent fuel pools vary in number among reactor facilities. 

OIG reviewed inspection reports issued over a 5-year period at a sample 

of reactor licensees.24 The sample included 18 operating nuclear power

plants with 25 spent fuel pools. For fiscal years 2010 through 2014,

 23 This list of inspection procedures is not a comprehensive list within the ROP. Rather, it is a list of 

inspection procedures where, according to resident inspectors, spent fuel pools could be inspected even 

though the pools are not specifically mentioned.

24 The sample of facilities is discussed in Appendix A, Objective, Scope, and Methodology, of this report.
Audit of NRC’s Oversight of Spent Fuel Pools

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• There were 1,061 total inspection reports published for the 18 

reactor facilities, with many of the reports discussing results of

several inspection procedures.

• Of the 1,061 reports, there were only 67 spent fuel pool-related 

inspections using elective procedures.

25

 

• Although these 67 total inspection procedures equate to nearly 4

spent fuel pool inspections per facility over the 5-year time period, 

some facilities had as many as 10 inspections during this timeframe

while other facilities had no inspections.

Neutron Absorbers Not Focus of Inspectors

NRC has documented industry operating experience involving the 

degradation of neutron absorbers such as Boraflex. However, NRC’s 

efforts to learn more about the long-term behavior of other neutron 

absorbers have been challenged as the tools used to evaluate Boraflex 

may not be reliable with other neutron absorbers. Numerous NRC staff 

stated that although not an immediate safety concern, neutron absorber 

degradation is probably the most important spent fuel pool safety issue 

and learning more about degradation is a priority for NRR. However, 

neutron absorbers largely do not fall in the regional or resident inspectors’ 

purview. Inspectors indicated awareness of the issues with neutron 

absorbing materials. Nevertheless, the extent of a resident inspector’s 

direct experience related to neutron absorbers and how they are 

monitored or managed by the licensee depends on conditions at the 

plants.

Shutdown Plant Spent Fuel Pool Inspections Do Not Consistently Reflect 

Recent Operating Experience 

At shutdown power plants, NRC regional inspectors conduct annual 

inspections using Inspection Procedure 60801, “Spent Fuel Pool Safety at 

Permanently Shutdown Reactors,” issued in 1997. 

 25 These inspections do not include the mandatory security or reactor outage activities inspections. 

Furthermore, other inspections that may have touched spent fuel pools in some capacity, such as 

radiation protection and license renewal, were not included since their focus is not on spent fuel pools. 

Finally, one-time inspections such as temporary instructions also were not included.
Audit of NRC’s Oversight of Spent Fuel Pools

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Inspection procedures from the ROP 

baseline program can also be used at 

decommissioning facilities, thus enhancing 

inspection effectiveness with operating 

experience. Also available to enhance 

inspection effectiveness are five NRC 

Information Notices based on spent fuel 

pool operating experience issued since IP 

60801 was published. 

However, OIG’s review of spent fuel pool inspections at shutdown facilities 

over the past 5 years showed only 3 of 26 cases where operating 

experience may have informed the inspection. For example, one 

inspection included the Temporary Instruction for followup to the 

Fukushima Dai-ichi event, demonstrating use of industrywide operating 

experience. In the majority of cases, however, inspection reports reflected 

close adherence to the requirements of Inspection Procedure 60801 

without incorporating additional operating experience. 

Inspection Program Guidance Virtually Silent or Outdated

Inspection program guidance is insufficient because ROP is virtually silent 

on operating spent fuel pools and shutdown facility inspection guidance is 

outdated. 

Virtual Silence in ROP

For operating reactors, other than the mandatory reactor outage activities 

and security inspections, only one inspection procedure in the ROP 

baseline inspection program mentions the spent fuel pool as a system that 

could be included electively in an inspection sample. The procedures 

cited by resident inspectors listed in Table 2 do not explicitly call out the 

spent fuel pool in the discussion of samples. As a result, spent fuel pools 

were rarely included in samples when these inspection procedures were 

used by inspectors. 

Why This Occurred

Permanently shutdown reactors at 

San Onofre Station. Source: NRC.
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Although some inspectors explained that they maintain awareness of the 

spent fuel pool condition through their plant status observations, 

Inspection Manual Chapter 2515 Appendix D, “Plant Status,” makes no 

mention of spent fuel pools and only advises inspectors to “cover all 

spaces” of a power plant. Overall, explicit inspection guidance is not 

provided for spent fuel pools at operating reactors, in contrast to the 

specific guidance to review such areas as drain and siphon protection, 

instrumentation, and leakage detection during inspections of spent fuel 

pools at permanently shutdown reactors. 

Inspectors also do not have a clear means in the inspection guidance to 

oversee licensees’ monitoring of neutron absorbers. Some inspectors 

reported being “asked” to look at licensee monitoring efforts, but, as one 

resident inspector put it, neutron absorbers are largely a “headquarters 

thing.” Another resident observed that he “has never personally looked at 

this [neutron absorbers]” and his guess is that “the region never has 

either.” Headquarters staff acknowledged that, for many nuclear power 

plants, there is no NRC-endorsed aging management program for 

neutron- absorbing material. As such, it is extremely difficult for inspectors 

to oversee a program for which a standard currently does not exist. 

Decommissioning Guidance Outdated

For shutdown plants, Inspection Manual Chapter 2561, “Decommissioning 

Power Reactor Inspection Program,” published in 2003, and Inspection 

Procedure 60801, published in 1997, have become outdated. These 

guidance documents do not reflect more recent operating experience, 

such as higher fuel enrichments, denser and more complex storage 

patterns, and unexpected (and potentially unknown) deterioration of spent 

fuel pool neutron absorber material, nor do they reflect current practices in 

aging management.
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Spent Fuel Pools Could Potentially Be Overlooked

Spent fuel pools are not being inspected with regularity and could 

potentially be overlooked. License renewals, decommissioning, and the 

lack of a long-term solution to spent fuel storage means that some spent 

fuel pools may store fuel for many years. Although largely viewed as 

passive or static between refueling outages, spent fuel pool degradation 

may become more significant due to aging as pools are kept in service for 

longer periods of time. Given the low number of inspections, other than 

for reactor outages and security, prudence suggests that the extension of 

time in service could increase risk of onsite consequences for workers or 

the local environment.

Further, more plants are going into decommissioning status. The most 

recently shutdown plants have more high burnup fuel and higher density 

pools than was foreseen in the existing guidance, possibly reducing the 

overall effectiveness of the inspections.

Recommendations

OIG recommends that the Executive Director for Operations

2. Develop and implement spent fuel pool inspection guidance at 

operating reactors.

3. Develop an enforceable neutron-absorbing material aging 

management program.

4. Update Inspection Manual Chapter 2561 and Inspection Procedure 

60801.

Why This Is Important
Audit of NRC’s Oversight of Spent Fuel Pools

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Summary and Conclusion

NRC should apply regulatory tools consistently across and within agency 

program areas, and regulate in a manner that clearly communicates 

requirements and ensures that regulations are practical and consistently 

applied. NRC also must maintain effective and consistent oversight of 

licensee performance to drive continued licensee compliance with NRC 

safety requirements and license conditions. Effective guidance for 

submitting and reviewing criticality analyses will help enhance program 

efficiency and effectiveness. Further, as time in service increases for 

spent fuel pools, guidance for inspections in the areas most subject to 

degradation will help ensure continued safe operations.
Audit of NRC’s Oversight of Spent Fuel Pools

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OIG recommends that the Executive Director for Operations

1. Provide a generic regulatory solution for spent fuel pool criticality 

analysis by developing and issuing detailed licensee guidance 

along with NRC internal procedures.

2. Develop and implement spent fuel pool inspection guidance at 

operating reactors.

3. Develop an enforceable neutron-absorbing material aging 

management program.

4. Update Inspection Manual Chapter 2561 and Inspection Procedure 

60801.

 IV. CONSOLIDATED LIST OF RECOMMENDATIONS
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An exit conference was held with the agency on January 22, 2015. Prior to 

this meeting, after reviewing a discussion draft, agency management 

provided supplemental information that has been incorporated into this report, 

as appropriate. As a result, agency management stated their general 

agreement with the findings and recommendations in this report and opted 

not to provide formal comments for inclusion in this report.

 V. AGENCY COMMENTS
Audit of NRC’s Oversight of Spent Fuel Pools

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Appendix A

Objective

The audit objective was to determine if NRC’s oversight of spent fuel pools 

and the nuclear fuel they contain provides adequate protection for public 

health and safety, and the environment.

Scope

The audit focused on reviewing current NRC oversight processes for wet 

storage of spent reactor fuel in pools at operating and permanently 

shutdown reactors. We conducted this performance audit at NRC 

headquarters (Rockville, MD) from July 2014 through November 2014. 

We also visited two nuclear power plants in Hancocks Bridge, New Jersey

during this time. Internal controls related to the audit objective were 

reviewed and analyzed. Throughout the audit, auditors were aware of the 

possibility of fraud, waste, or abuse in the program.

Methodology

OIG reviewed relevant criteria, such as Federal legislation pertaining to 

NRC’s regulatory authorities to oversee spent fuel pools, including the 

Atomic Energy Act of 1954, as amended; the Energy Reorganization Act 

of 1974; and the Nuclear Waste Policy Act of 1982. OIG reviewed 

relevant portions of Title 10 of the Code of Federal Regulations, 

particularly 10 CFR Part 50 Domestic Licensing of Production and 

Utilization Facilities. OIG reviewed NRC’s Strategic Plan, Fiscal Years 

2014-2018, and NRC’s Principles of Good Regulation. OIG reviewed the

Government Accountability Office’s “Standards for Internal Control in the 

Federal Government” and the Office of Management and Budget’s “Final 

Bulletin for Agency Good Guidance Practices.”

OIG reviewed NRC guidance documents such as Standard Review Plans, 

Inspection Manual Chapters, Inspection Procedures, and other guidance

pertaining to spent fuel pools. OIG reviewed NRC communications 

 OBJECTIVE, SCOPE, AND METHODOLOGY
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with licensees, including Information Notices, Generic Letters, 

Enforcement Actions (Orders), and summaries of public meetings with 

licensees and industry representatives. OIG reviewed reports of research 

by NRC, the Electric Power Research Institute, and the National Academy 

of Sciences addressing aspects of spent fuel pools in the United States. 

OIG conducted records reviews during the course of the audit. 

Specifically, the audit team reviewed safety inspection reports of a 

judgmentally selected sample of 18 plants covering a 5-year period (Fiscal 

Years 2010 – 2014) to determine the frequency of spent fuel pool related 

safety inspections. Additionally, the audit team reviewed inspection 

reports, issued over a 5-year period, of spent fuel pools at permanently 

shutdown reactors. OIG also reviewed Operating Experience and the 

Reactor Oversight Process Plant Information Matrix for information on 

spent fuel pool performance and inspection findings.

OIG interviewed NRC staff and management at headquarters and the 

regions to gain an understanding of the roles and responsibilities related 

to oversight of spent fuel pool safety. Auditors interviewed management 

and staff from NRR, the Office of New Reactors, the Office of Nuclear 

Regulatory Research, the Office of Nuclear Material Safety and

Safeguards, and the Advisory Committee on Reactor Safeguards. 

Additionally, OIG interviewed staff from each of the four regions (Region I, 

King of Prussia, PA; Region II, Atlanta, GA; Region III, Lisle, IL; and 

Region IV, Arlington, TX) who participate in activities related to spent fuel 

pools. More specifically, OIG conducted telephone interviews with senior 

resident inspectors and resident inspectors at 18 operating nuclear power 

plants. Those plants were selected as a judgmental sample to include 

both boiling water reactors and pressurized water reactors in all the 

regions, a range of facility ages, and a range of spent fuel pool capacities.

OIG conducted telephone interviews with staff in Regions I, III, and IV 

responsible for oversight of spent fuel pools at permanently shutdown 

facilities. 

OIG conducted interviews with representatives of the Nuclear Energy 

Institute and with licensees and other stakeholders interested in spent fuel 

pool safety. The audit team toured the spent fuel pools at the Hope 
Audit of NRC’s Oversight of Spent Fuel Pools

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Creek Generating Station and Salem Nuclear Generating Station in 

Hancocks Bridge, New Jersey, to observe a boiling water reactor and a 

pressurized water reactor spent fuel pool system and to speak with 

inspectors about their onsite inspection activities. 

We conducted this performance audit in accordance with generally 

accepted Government auditing standards. Those standards require that 

we plan and perform the audit to obtain sufficient, appropriate evidence to 

provide a reasonable basis for our findings and conclusions based on our 

audit objectives. We believe that the evidence obtained provides a 

reasonable basis for our findings and conclusions based on our audit 

objectives. 

The audit work was conducted by Sherri Miotla, Team Leader; Michael 

Blair, Audit Manager; Kevin Nietmann, Senior Technical Advisor; Amy 

Hardin, Senior Auditor; and Regina Revinzon, Auditor.
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 COMMENTS AND SUGGESTIONS

 TO REPORT FRAUD, WASTE, OR ABUSE

Please Contact:

Email: Online Form

Telephone: 1-800-233-3497

TDD 1-800-270-2787

Address: U.S. Nuclear Regulatory Commission

Office of the Inspector General

Hotline Program

Mail Stop O5-E13

11555 Rockville Pike

Rockville, MD 20852

If you wish to provide comments on this report, please email OIG using this link.

In addition, if you have suggestions for future OIG audits, please provide them using 

this link.