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Modernizing the active neutron collar poison rod correction using simulations to enhance PWR fresh fuel verification

The declared inventory of 235 U in fresh, low enriched uranium, nuclear fuel assemblies is routinely verified by nuclear safeguards inspectorates using the UNCL (Uranium Neutron Collar – Light Water Reactor Fuel) nondestructive assay instrument. The trend in modern fuels is towards higher initial enrichment, which in turn requires a larger number of burnable poison pins with higher Gadolinia concentration to hold down the initial reactivity. UNCL assay error for modern fuel assemblies typically exceeds 10%. The traditional algorithm used to correct the response for burnable poison content needs revision to achieve accuracy comparable to the $\sigma_\text{R}$ of 4.5% expected for poison-free assemblies. Here we review the problem and use a large set of 287 Monte Carlo simulations based on an experimentally benchmarked model corresponding to the 16×16 PWR array used in Brazilian Angra type II and III fuel. Simulated relative responses are used to evaluate the functional form of the poison correction and determine parameters optimal for 16×16 PWR assemblies. This update is conducted using between 4–24 Gadolinia pins ranging 2–11 wt% Gd 2 O 3 with assemblies having mean enrichments ranging 2.5%–5%. Experimental validation of the updated coefficients using seven measurements shows bias is reduced by an order of magnitude and $\sigma_\text{R}$R reduced from 10% to less than 2%. Two updated sets of coefficients are provided, the most accurate of which is directly useable in the existing analysis code (INCC) in use by inspectorate at fuel fabrication facilities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Detection of Diversion in a Realistic Heat Pipe Microreactor Using Supervised Machine Learning

Microreactors (MRs) pose new challenges for international safeguards. Here, their small size and mass reproducibility make them ideal for deployment in greater numbers and in remote locations, making the job of safeguards inspectors more challenging. Machine learning (ML) is currently being applied to many fields to augment human performance and increase automation; in particular, ML could be used to provide insight for international inspectors to help detect the diversion of nuclear fuel from MR cores. Four ML model types (k-nearest neighbors, decision tree, random forest, and histogram-based gradient boosted ensemble) were trained on integrated flux and critical control drum angle data generated with Serpent 2 for a realistic heat pipe MR design, achieving nearly 100% binary classification accuracy of nominal and diversion core configurations by the end of 1 full power year for three of the four model types. Regression model variants were also trained, using the same input data, for predicting the number of fuel pins diverted. Root-mean-square errors below 5% of the total number of fuel pins were achieved by the 1 full power year mark for all models.

22 - GENERAL STUDIES OF NUCLEAR REACTORS↗

Low-Intrusion Techniques and Sensitive Information Management for Warhead Counting and Verification: FY2011 Annual Report

Future arms control treaties may push nuclear weapons limits to unprecedented low levels and may entail precise counting of warheads as well as distinguishing between strategic and tactical nuclear weapons. Such advances will require assessment of form and function to confidently verify the presence or absence of nuclear warheads and/or their components. Imaging with penetrating radiation can provide such an assessment and could thus play a unique role in inspection scenarios. Yet many imaging capabilities have been viewed as too intrusive from the perspective of revealing weapon design details, and the potential for the release of sensitive information poses challenges in verification settings. A widely held perception is that verification through radiography requires images of sufficient quality that an expert (e.g., a trained inspector or an image-matching algorithm) can verify the presence or absence of components of a device. The concept of information barriers (IBs) has been established to prevent access to relevant weapon-design information by inspectors (or algorithms), and has, to date, limited the usefulness of radiographic inspection. The challenge of this project is to demonstrate that radiographic information can be used behind an IB to improve the capabilities of treaty-verification weapons-inspection systems.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Safeguards Approaches for Very Long-Term Storage of Spent Fuel

Many States are considering interim very long-term storage (VLTS) strategies for spent fuel storage while final disposition options are developed. Under the VLTS approach, spent fuel will be stored for periods that could exceed 50 to 100 years. The long-term storage of spent fuel — and the increasing stockpile of plutonium contained in this spent fuel — exacerbate the international safeguards and verification needs for spent fuel. In particular, significant delays in any verification of the contents of spent fuel assemblies prior to disposition may cause even further delays in the final disposition (or reprocessing) of spent fuel. As a result, the resources required by the International Atomic Energy Agency (IAEA) to safeguard the increasing stockpile of spent fuel will increase. Safeguarding these interim storage facilities and subsequently, the transportation of long-term stored fuel, will place additional demands on IAEA resources if the current approach, which relies heavily upon inspectors being present at the facility, is to be continued. Current IAEA approaches to safeguarding above ground dry storage sites do not take into account the challenges associated with longer-term storage and are also very dependent on inspector presence. The IAEA is moving toward remote and unattended monitoring systems for safeguards and these systems should be utilized at VLTS facilities as much as possible. The research and development of various monitoring systems should be continued.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Opportunities for Process Monitoring Techniques at Delayed Access Facilities

Except for specific cases where the International Atomic Energy Agency (IAEA) maintains a continuous presence at a facility (such as the Japanese Rokkasho Reprocessing Plant), there is always a period of time or delay between the moment a State is notified or aware of an upcoming inspection, and the time the inspector actually enters the material balance area or facility. Termed by the authors as “delayed access,” this period of time between inspection notice and inspector entrance to a facility poses a concern. Delayed access also has the potential to reduce the effectiveness of measures applied as part of the Safeguards Approach for a facility (such as short-notice inspections). This report investigates the feasibility of using process monitoring to address safeguards challenges posed by delayed access at a subset of facility types.

Delayed access↗

Measure Guideline: Combustion Safety for Natural Draft Appliances Using Indoor Air

This Measure Guideline covers how to assess and carry out the combustion safety procedures for appliances and heating equipment that uses indoor air for combustion in low-rise residential buildings. Only appliances installed in the living space, or in an area freely communicating with the living space, vented alone or in tandem with another appliance are considered here. A separate Measure Guideline addresses combustion appliances located either within the living space in enclosed closets or side rooms or outside the living space in an adjacent area like an attic or garage that use outdoor air for combustion. This document is for inspectors, auditors, and technicians working in homes where energy upgrades are being conducted whether or not air infiltration control is included in the package of measures being applied. In the indoor combustion air case, guidelines summarized here are based on language provided in several of the codes to establish minimum requirements for the space using simplified prescriptive measures. In addition, building performance testing procedures are provided by testing agencies. The codes in combination with the test procedures offer comprehensive combustion safety coverage to address safety concerns, allowing inexperienced residential energy retrofit inspectors to effectively address combustion safety issues and allow energy retrofits to proceed.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Euratom Fast Collar (EFC) Calibration Report

Neutron collars are used by international inspectorates to determine the amount of 235U in fresh LWR fuel assemblies. Standard neutron collars can operate in two modes: “fast” and “thermal”. In fast mode (using cadmium liners), thermal neutron are excluded from the assembly and the measurement results are not very sensitive to the presence of neutron poison loaded pins. In thermal mode, the thermal neutrons are affected by the presence of poison rods leading to significant effect, requiring corrections. These corrections depend on the declaration of the operator, reducing the independence of the inspectors’ measurements. The thermal mode signal is much higher than the fast mode signal and can give statistically acceptable results in ~600 seconds compared with ~1 hr for the fast mode. This report describes the calibration of a new fast neutron collar designed to use fast mode to reduce the effect of poison pins on verification measurements and with increased efficiency to reduce the measurement times to those normally used on inspection. The work was done in cooperation with the safeguards division of the European Commission and so the new collar is named the Euratom Fast Collar (EFC). The motivation and design work is presented in reference 2. The Monte Carlo simulations presented in reference 2 cover a larger parameter range than can be experimentally measured with the mock up assembly and so we base the performance on the simulation results, benchmarked to the measurements. The work presented here follows that of the “bible” of LWR fuel assembly measurements and uses the same mock-up assembly, with the same enriched, depleted and gadolinium poisoned fuel rods as were used in that work. Reference 1 describes how the measured count rate of the detector is corrected for AmLi source strength, electronic stability, efficiency, poison rods effects and heavy metal effects as well as other perturbing factors. These will be discussed below. INCC is the normal software that is used to collect and analyze neutron collar data. The results of this work have been formulated to fit into this existing INCC data analysis framework.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Combustion Safety for Appliances Using Indoor Air (Fact Sheet)

This measure guideline covers how to assess and carry out the combustion safety procedures for appliances and heating equipment that uses indoor air for combustion in low-rise residential buildings. Only appliances installed in the living space, or in an area freely communicating with the living space, vented alone or in tandem with another appliance are considered here. A separate measure guideline addresses combustion appliances located either within the living space in enclosed closets or side rooms or outside the living space in an adjacent area like an attic or garage that use outdoor air for combustion. This document is for inspectors, auditors, and technicians working in homes where energy upgrades are being conducted whether or not air infiltration control is included in the package of measures being applied. In the indoor combustion air case, guidelines summarized here are based on language provided in several of the codes to establish minimum requirements for the space using simplified prescriptive measures. In addition, building performance testing procedures are provided by testing agencies. The codes in combination with the test procedures offer comprehensive combustion safety coverage to address safety concerns, allowing inexperienced residential energy retrofit inspectors to effectively address combustion safety issues and allow energy retrofits to proceed.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

CMM Interim Check Design of Experiments (U)

Coordinate Measuring Machines (CMM) are widely used in industry, throughout the Nuclear Weapons Complex and at Los Alamos National Laboratory (LANL) to verify part conformance to design definition. Calibration cycles for CMMs at LANL are predominantly one year in length and include a weekly interim check to reduce risk. The CMM interim check makes use of Renishaw’s Machine Checking Gauge which is an off-the-shelf product simulates a large sphere within a CMM’s measurement volume and allows for error estimation. As verification on the interim check process a design of experiments investigation was proposed to test a couple of key factors (location and inspector). The results from the two-factor factorial experiment proved that location influenced results more than the inspector or interaction.

42 ENGINEERING↗

Measure Guideline: Combustion Safety for Natural Draft Appliances Using Indoor Air

This measure guideline covers how to assess and carry out the combustion safety procedures for appliances and heating equipment that uses indoor air for combustion in low-rise residential buildings. Only appliances installed in the living space, or in an area freely communicating with the living space, vented alone or in tandem with another appliance are considered here. A separate measure guideline addresses combustion appliances located either within the living space in enclosed closets or side rooms or outside the living space in an adjacent area like an attic or garage that use outdoor air for combustion. This document is for inspectors, auditors, and technicians working in homes where energy upgrades are being conducted whether or not air infiltration control is included in the package of measures being applied. In the indoor combustion air case, guidelines summarized here are based on language provided in several of the codes to establish minimum requirements for the space using simplified prescriptive measures. In addition, building performance testing procedures are provided by testing agencies. The codes in combination with the test procedures offer comprehensive combustion safety coverage to address safety concerns, allowing inexperienced residential energy retrofit inspectors to effectively address combustion safety issues and allow energy retrofits to proceed.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Orange County Photovoltaic Project & Educational COmponent

The purpose of this report is to discuss the projects implemented, utilizing Department of Energy grant funds, to support the use and understanding of renewable energy in Orange County, Florida and the Greater Orlando Area. Orange County is located in the State of Florida and is most popularly referred to as Orlando. The greater Orlando area’s current population is 1,225,267 and in 2015 was the first destination to surpass 60 million visitors. Orange County utilized grant funds to add to the growing demand for access to charging stations by installing one level 2 dual NovaCharge CT4021 electric vehicle charging station at the Orange County/University of Florida Cooperative Extension Center. The charging station is considered a “smart” charger connected to a central network operated by a third party. Data collected includes the number of charging sessions, session start and end times, the electricity usage, greenhouse gases saved and other pertinent data used for reporting purposes. Orange County continues to support the use of electric vehicles in Metro Orlando and this project continues to bring awareness to our public regarding using alternative vehicles. Additionally, we offer all visitors to the Orange County/University of Florida Cooperative Extension Center free charges for their electric vehicles 24 hours a day. Since the operation of the charging station there have been 52 unique driver users, a total of 532.2258 kg of greenhouse gas savings and 159.03 gallons of gasoline savings. The installation of the additional electric vehicle charging station is part of a county-wide goal of promoting implementation of renewable energy technologies as well as supporting the use of electric vehicles including the Drive Electric Orlando & Florida programs. http://driveelectricorlando.com/ & ; http://www.driveelectricflorida.org/ . Grant funds were also used for Outreach and Educational efforts. Educational efforts about renewable energy were accomplished through the continued support as well as a proposed expansion and potential relocation of the Climate Change Education Center. The growth of the Climate Change Education Center focused on 2 educational subsectors. The first educational sector focused on an apprenticeship with university students. The second sector Orange County partnered with a hospitality college that held seminars to educate students in sustainability best practices that would influence the industry as a whole as students take jobs around the U.S. and other parts of the world. Orange County completed five of the originally proposed six educational seminars. The first seminar focused on community based social marketing techniques for driving sustainable behavior changes. The second seminar held was a green team workshop. The third seminar focused on urban sustainability planning. The fourth and fifth seminars held were Florida Energy Code workshops for building inspectors. A sixth transit oriented development seminar in partnership with Rollins College was explored, but was not conducted because the proposed on campus venue was not accessible for an extended period of time due to renovations. Additionally, an ENERGY STAR training program was conducted with students from the University of Central Florida; three of the five buildings assessed received ENERGY STAR ratings; one student completed the training and received their certification as an ENERGY STAR Specialist. Background: Location: Orange County is located in the central region of the State of Florida and is most popularly known for including the City of Orlando. The greater Orlando area’s current population is 1,225,267 and is home to large corporations such as Walt Disney World, Universal Studios Orlando, Ritz Carlton, Darden Restaurants, and the nation’s second largest convention center. Opportunities Identified: Encouraging Sustainability in Major Sectors: The Central Florida economy is largely dependent on the hospitality industry and in 2015 it was the first destination to surpass 60 million visitors. With over 60 million visitors each year, 120,000 hotel rooms, 4,000 restaurants, and 75 theme parks and attractions, the local hospitality industry provided a wealth of opportunity to reduce greenhouse gas emissions through building energy efficiency and renewable energy. Accordingly, Central Florida is an ideal training ground for teaching best practices for sustainability focused on the hospitality industry. Meeting the Growing Demand for Electric Vehicle Infrastructure: According to the 2014 U.S Clean Tech Leadership Index Report, nationwide electric vehicle ownership in the top 50 largest metro areas increased sharply in 2013; the Orlando Metro Area was ranked #5 in the nation in in terms of electric vehicle charging stations per one million people. Additionally, the Orange County 2014-2015 Annual Sustainable Orange County Report indicated there are 300 electric vehicle charging stations in Central Florida (roughly 300 charging stations within ~70 mile radius available to our residents of Orange County). By increasing and improving access to charging stations, Orange County supports the growing demand for renewable energy technologies. Project Achievements/Accomplishments: Installed an Electric Charging Station: Orange County utilized grant funds to install one level 2 dual NovaCharge CT4021 electric vehicle charging station at the Orange County/University of Florida Cooperative Extension Center. The charging station is considered a “smart” charger connected to a central network operated by a third party that monitors the number of charging sessions, session start and end times, the electricity usage, greenhouse gases saved and other pertinent data. During the six months of operation of the charging station there have been 52 unique driver users of the charging station; a total of 532.2258 kg of greenhouse gas savings and 159.03 gallons of gasoline savings. Operation and Potential Relocation of the Orange County Climate Change Education Center: The Climate Change Education Center, originally located within the Orange County Convention Center, served as a central place to inform and educate commercial and residential sectors of environmental, health, and economic benefits of renewable energy, energy efficiency, and greenhouse gas emission reductions. Grant funds were used to pay for the rent required to maintain a lease at the Convention Center, conduct five educational workshops, and for planned upgrades to the Center displays highlighting a number of energy efficiency and renewable energy projects implemented at the Orange County Convention Center and Downtown Orange County. An initial design concept for an upgraded Climate Change Education Center and educational displays was proposed. However, after the Convention Center determined the space occupied by the Climate Change Education Center; a feasibility study for relocation to the proposed area was conducted in October 2013. In December 2013, it was determined that the desired location of the for the Climate Change Education Center at the Orange County Extension Education Center provided too many construction challenges for relocation with too many building retrofits and access problems, including lack of access for loading and unloading exhibits as well as roof drainage relocations and sewer service connection issues. Another suitable location for relocating the Climate Change Education Center could not be located so the project was terminated. The Climate Change Education Center is no longer in existence in Orange County and has been eliminated. Grant funds were used to pay for marketing services for a state wide marketing program including solar & other renewable energy technologies for rebranding and developing marketing materials including web site design and updating. A website was maintained and updated the www.PowerUpGreenEnergy.com website (no longer in service). Sustainability Training for the Hospitality Industry and Major Sectors: To introduce energy efficiency and renewable energy concepts to the hospitality industry, Orange County partnered with a hospitality college that held seminars to educate students in sustainability best practices that would influence the industry as a whole as students take jobs around the U.S. and other parts of the world. Orange County completed five of the originally proposed six education seminars. Seminar topics included: driving sustainable behavior change through community based social marketing; green team programs; urban sustainability planning; and Florida Energy Code workshops for building inspectors. In partnership with Rollins College, a sixth seminar focused on transit-oriented development was explored, but was not conducted due to extended renovations at the proposed on-campus venue. Green Job Training Development: To promote green industry development and on-the-job training in occupations that encourage energy efficiency and resource reduction, Orange County piloted an ENERGY STAR training and apprenticeship program with students from the University of Central Florida; three students applied for the program; one student completed the training and received their certification as an ENERGY STAR specialist; three of the five buildings assessed received ENERGY STAR Ratings.

14 SOLAR ENERGY↗

A Radiation-Triggered Surveillance System for UF6 Cylinder Monitoring

This report provides background information and representative scenarios for testing a prototype radiation-triggered surveillance system at an operating facility that handles uranium hexafluoride (UF 6 ) cylinders. The safeguards objective is to trigger cameras using radiation, or radiation and motion, rather than motion alone, to reduce significantly the number of image files generated by a motion-triggered system. The authors recommend the use of radiation-triggered surveillance at all facilities where cylinder paths are heavily traversed by personnel. The International Atomic Energy Agency (IAEA) has begun using surveillance cameras in the feed and withdrawal areas of gas centrifuge enrichment plants (GCEPs). The cameras generate imagery using elapsed time or motion, but this creates problems in areas occupied 24/7 by personnel. Either motion-or-interval-based triggering generates thousands of review files over the course of a month. Since inspectors must review the files to verify operator material-flow-declarations, a plethora of files significantly extends the review process. The primary advantage of radiation-triggered surveillance is the opportunity to obtain full-time cylinder throughput verification versus what presently amounts to part-time verification. Cost savings should be substantial, as the IAEA presently uses frequent unannounced inspections to verify cylinder-throughput declarations. The use of radiation-triggered surveillance allows the IAEA to implement less frequent unannounced inspections for the purpose of flow verification, but its principal advantage is significantly shorter and more effective inspector video reviews.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Shell Inspection History and Current CMM Inspection Efforts

The following report provides a review of past and current CMM Shell Inspection efforts. Calibration of the Sheffield rotary contour gauge has expired and the primary inspector, Matthew Naranjo, has retired. Efforts within the Inspection team are transitioning from maintaining and training new inspectors on Sheffield to off-the-shelf CMM technology. Although inspection of a shell has many requirements, the scope of the data presented in this report focuses on the inner contour, outer contour, radial wall thickness and mass comparisons.

42 ENGINEERING↗

Reliability Assessment of Remote Visual Examination

Remote visual testing (RVT) is a commonly used nondestructive examination method for inservice inspection (ISI) of reactor internals to detect cracking and gross component failures. Despite widespread use, the detection reliability of RVT and the factors that impact overall RVT performance have been unresolved issues. This report describes the results from an assessment sponsored by the U.S. Nuclear Regulatory Commission and conducted by the Pacific Northwest National Laboratory, in cooperation with the Electric Power Research Institute, for evaluating the reliability of RVT methods currently being used for [reactor] in-vessel visual inspection. The goal was to assess the performance of commercially applied RVT examination procedures implemented by qualified personnel, as well as to identify and qualitatively assess enhancements to examination procedures for detecting flaws in test specimens. The assessment was performed over three phases of research, with the results of the first phase used to identify key controllable parameters impacting RVT performance and to design the next two phases (round-robin testing). Participants in the round-robin tests included teams of inspectors from commercial nuclear power ISI vendors. Participants were asked to determine if a specimen contained a crack and its approximate location, orientation, and length. The detection and location information were used to compute estimates of the probability of detection and false call probability for various scenarios such as the placement and orientation of the flaw on the specimen, team-to-team variations in detection performance, and effects of secondary review on RVT detection. Results showed that crack opening displacement (COD) is the dominant factor in the reliability of crack detection using commercially applied RVT procedures, with crack length being weakly correlated with detection probability. The implication is that RVT detection is likely heavily dependent on the contrast produced by the crack opening, with crack detection becoming less reliable as the COD decreases. Further, the results indicated RVT will be challenged when cracks are located in the vicinity of surface features such as scratches or weld ripples, or close to the edge of welds where shadowing and/or the presence of weld undercuts may complicate the ability to detect the crack. The assessment also reinforced earlier findings on the importance of lighting in flaw detection and appeared to align with other studies that find improved reliability when using multiple inspectors or analysts. Finally, the results pointed to the importance of practice with specimens that mimic conditions likely to be found in the field. Based on the findings and limitations of the assessment, a number of recommendations are made regarding best practices for improving the reliability of RVT in a field setting and for addressing remaining informational gaps. This report describes the design and noted limitations of the three phases of research, the analysis methodology for each phase, and the results of the research. The results of this assessment provide a benchmark set of data on the reliability of RVT for detecting cracking, assuming the implementation of field-like inspection procedures. The likely impact of several uncontrolled factors on RVT detection performance are discussed, and recommendations regarding the use of these results to assess field performance are provided. Finally, recent advances in RVT technology are briefly discussed and point to the potential need for continued research to evaluate the capability and effectiveness of the technique as improvements are implemented.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Design Considerations for the Field Use of Safeguards Technology

The process of safeguards technology development, deployment, and use should be carried out in such a way that it supports the International Atomic Energy Agency’s (IAEA’s) international safeguards verification mission, while also being efficient in terms of both cost and time. This process, however, may be hindered by a lack of communication between the scientists or engineers developing the technology and the safeguards inspectors who would be using the equipment, as well as by a general lack of facility experience among the scientists or engineers designing safeguards technology. The latter point is particularly true for new graduates and junior staff working at design laboratories, who typically have not had significant experience in an industrial facility setting or in working with or for the IAEA directly. As a result, junior safeguards staff may have difficulty understanding inspector needs and the limitations of using safeguards technology in the field, often leading to inefficiencies (in the form of increased cost and time spent) in the safeguards technology design process. To mitigate this knowledge gap, the Y-12 National Security Complex in Oak Ridge, Tennessee, has developed a list of design considerations that should be incorporated when developing safeguards technology. Project findings with respect to nondestructive assay technology are detailed in this paper.

99 GENERAL AND MISCELLANEOUS↗

Action Sheet 55 Measurement Campaign Summary

Neutron collars have long been used by international inspectorates to determine the 235 U loading of fresh light water reactor (LWR) fuel in nuclear fuel fabrication facilities. Burnable poisons are strong thermal neutron absorbers that are frequently used to increase the lifetime of LWR fuel in a reactor. These poisons have made the traditionally thermal neutron collar measurements challenging because they force inspectors to rely on operator declarations of the burnable poison content of the fuel in order to correct for the decreased count rate caused by the added thermal neutron absorption of the poison. Work has been conducted internationally to try to eradicate the reliance on operator declarations. The Euratom Fast Collar for BWR Fuel (EFCB) is one promising technique to manage this issue.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Minimally Intrusive Verification of Deep Nuclear Warhead Reductions: A Fresh Look at the Buddy-Tag Concept

Future nuclear arms - control agreements may place numerical limits on the total number of warheads in the nuclear arsenals of states. Verifying these limits may require inspectors to account for individual warheads, both deployed and non-deployed. This task could be accomplished with unique identifiers, but standard tagging techniques may be unacceptable in this case due to host concerns about safety and intrusiveness. To resolve this dilemma, we revisit the so - called Buddy Tag concept first proposed by Sandia National Laboratories in the early 1990s. The conceptual innovation in the Buddy Tag was to by separate the tag from the treaty limited item itself. Verification of the pairings between tags and limited items would take place during a short-notice inspection, where the host would be required to produce one buddy tag for each item. Sensors on the Buddy Tag would show that it had not been moved to the inspected site after the inspection was declared (e.g., within the last 24-48 hours). If the inspector counted more (or fewer) treaty limited items than Buddy Tags at the inspected site, a treaty violation could be asserted. Using a number of single-site inspections, an inspecting party can hold the host at risk for discovery of violating the treaty at an enterprise level by possessing more treaty limited items than the treaty allows. In this project, we developed a buddy-tag prototype for demonstration and evaluation purposes. This paper summarizes the performance requirements for an advanced Buddy Tag, the proposed conduct of operations, the design choices and functionalities of the different subsystems, and initial testing results. The report also summarizes peer review feedback obtained throughout the project.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

How To Maintain Effective IAEA Safeguards While Reducing Facility Impact

For almost twenty years, inspectors from the International Atomic Energy Agency have been visiting the K-Area Material Storage facility at the Savannah River Site where excess plutonium has been placed under IAEA safeguards as part of the United States Volunatary Offer Agreement. During that time, the mission of K-Area Complex has expanded from storage of nuclear matieral to glovebox operations in support of the National Nuclear Security Administration’s Plutonium Disposition program. With this change in mission, it is becoming increasingly challenging to manage facility staff radiation exposure and operating activities during the IAEA’s annual Physcial Inventory Verifications (PIV). This study has identified both near-term and long-term recommendations for IAEA monitoring protocols that would allow the IAEA to maintain effective safeguards of the material while decreasing the impact to the facility. A statisitical analysis has shown that reducing the number of containers measured during an annual PIV from 12 to 4 still ensures a high level of confidence in the confidence while reducing the inspector time in the facility amd with a corresponding significant reduction in personnel radiation exposure. A modified installation pattern of Remotely Monitored Sealing Arrays (RMSAs) is also proposed utilizing only the outer rows of arrays of stored material containers in the Stack Area (SA). The modified RMSA placement will provide equivalent protection, while significantly reducing personnel radiological exposure, manpower requirements and associated costs. With advances in technology, there are additional potential options in containment/surveillance and continuity of knowledge that would allow the agency to be outside of the facility during PIV measurements and have confidence in the accuracy and authencitity of the results.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗