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NASA NTRSDate not supplied

Pterodactyl: Coupled 6-Dof Integration of Guidance and Control Algorithms in Genesis

The NASA-funded Pterodactyl project seeks to advance the current state-of-the-art for entry vehicles by developing novel guidance and control technologies for Deployable Entry Vehicles (DEVs). This paper builds upon the Pterodactyl architecture that employed eight individually articulating flaps with two options for guidance, bank angle modulation with the Fully Numerical Predictor Corrector Entry Guidance technique (FNPEG) and angle of attack and sideslip modulation with FNPEG uncoupled range control (FNPEG URC). These, with a linear quadratic regulator (LQR) controller, had previously been presented in uncoupled 3-DOF trajectories. This work will show results from fully coupled 6-DOF simulations, leveraging recent advancements in trajectory simulation software, namely the Julia-based Genesis package. Preliminary results show good performance for angle of attack and sideslip modulation when using a controller designed at high dynamic pressure conditions.

range targeting↗

NASA NTRSDate not supplied

Application of A Dual-Quaternion Six Degree-of-Freedom Guidance to Human-Scale Mars Entry, Descent, and Landing

Landing humans on Mars comes with many challenges, including the execution of a safe and precise entry, descent, and landing (EDL) sequence. Various NASA studies have shown that there are a variety of EDL guidance methods that potentially offer solutions to the human-scale EDL precision landing problem and work is ongoing to assess new and novel methods. As part of these ongoing studies, a dual-quaternion-based six degree-of-freedom guidance algorithm was implemented in the Program to Optimize Simulated Trajectories II (POST2), a NASA-and industry-standard spacecraft trajectory and vehicle design tool. This algorithm considers both translational and rotational dynamics and casts the trajectory optimization problem as a quadratically constrained quadratic program (QCQP) with various constraints at discrete nodes throughout the trajectory. The QCQP problem is solved via an alternating direction method of multipliers (ADMM) approach, and the output is a discretized optimal trajectory. The guidance is applied to a NASA reference human-scale Mars EDL system, and results are compared and discussed.

Optimization↗

NASA NTRSDate not supplied

Application of A Dual-Quaternion Six Degree-of-Freedom Guidance to Human-Scale Mars Entry, Descent, and Landing

Optimization↗

DOE OSTI2017

Development of Criticality Safety Validation Guidance for NRC-Regulated Activities

Some guidance documents support validation of criticality safety evaluations for many system types, and some accommodate different regulators or regulatory requirements. While these reports address specific applications, no single document applies to all systems and incorporates both traditional and sensitivity/uncertainty-based validation techniques. Oak Ridge National Laboratory will develop a single reference report for the US Nuclear Regulatory Commission (NRC) that provides modern examples and suggested recommendations for a uniform approach for performing and documenting k eff calculation validations applicable to any system containing fissile material. The project will include a literature review and development of a new, comprehensive NUREG/CR document on nuclear criticality safety validation. The NUREG will address the following experiences from recent reviews: 1. Inappropriate critical experiment selection 2. Insufficient trending analysis 3. Incorrectly calculated 95/95 uncertainties 4. Failure to address how validation applies to safety analysis 5. Lack of goodness-of-fit testing in trending analyses 6. Incorrect use of commercial reactor critical data 7. Failure to meet bias determination methodology prerequisites 8. Inappropriate extrapolation of bias and uncertainty 9. Failure to identify validation analysis gaps and weaknesses 10. Inadequate validation analysis documentation the final report will provide guidance on use of trending analysis results, acceptable confidence levels for normality testing and trending analysis, management of validation analysis gaps and weaknesses, use of sensitivity and uncertainty analysis in validation analysis, and potential impact of correlations among critical experiments used in validation. It will also consolidate existing guidance documents using both traditional and sensitivity/uncertainty-based approaches. This document will support NRC-regulated activities, as well as validation used in criticality safety within other regulatory frameworks.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

DOE OSTI2017

Laser Guidance in C-Arm Cone-Beam CT-Guided Radiofrequency Ablation of Osteoid Osteoma Reduces Fluoroscopy Time

PurposeTo assess whether laser guidance can reduce fluoroscopy and procedure time of cone-beam computed tomography (CBCT)-guided radiofrequency (RF) ablations of osteoid osteoma compared to freehand CBCT guidance.Materials and Methods32 RF ablations were retrospectively analyzed, 17 laser-guided and 15 procedures using the freehand technique. Subgroup selection of 18 ablations in the hip–pelvic region with a similar degree of difficulty was used for a direct comparison. Data are presented as median (ranges).ResultsComparison of all 32 ablations resulted in fluoroscopy times of 365 s (193–878 s) for freehand and 186 s (75–587 s) for laser-guided procedures (p = 0.004). Corresponding procedure times were 56 min (35–97 min) and 52 min (30–85 min) (p = 0.355). The subgroup showed comparable target sizes, needle path lengths, and number of scans between groups. Fluoroscopy times were lower for laser-guided procedures, 215 s (75–413 s), compared to 384 s (193–878 s) for freehand (p = 0.012). Procedure times were comparable between groups, 51 min (30–72 min) for laser guidance and 58 min (35–79 min) for freehand (p = 0.172).ConclusionAdding laser guidance to CBCT-guided osteoid osteoma RF ablations significantly reduced fluoroscopy time without increasing procedure time.Level of EvidenceLevel 4, case series.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2019

Virtual Guidance of Percutaneous Transthoracic Needle Biopsy with C-Arm Cone-Beam CT: Diagnostic Accuracy, Risk Factors and Effective Radiation Dose

Purpose: C-arm cone-beam computed tomography-guided transthoracic lung core needle biopsy (CBCT-CNB) is a safe and accurate procedure for the evaluation of patients with pulmonary nodules. The purpose of our study was to evaluate the diagnostic performance, complication rates and effective radiation dose of CBCT-CNB with virtual guidance. Materials and Methods: We retrospectively collected data regarding 375 CBCT-CNBs performed with virtual guidance (XperGuide—Philips Healthcare, Best, The Netherlands) from January 2010 to June 2015 on 355 patients (mean age, 68.1 years ± 11.8; age range, 31–88 years). Patients were divided into groups and compared based on the diagnostic failure and lesion size (15 mm cutoff). Diagnostic performance, complication rate and effective radiation dose were investigated. Variables influencing diagnostic performance and complications were assessed using Student’s T test and Pearson’s χ{sup 2} test. Results: The sensitivity, specificity, positive and negative predictive value and accuracy for patients subjected to CNBs were 96.8%, 100%, 100%, 100% and 97.2%, respectively. Considering risk factors for pneumothorax, no significant differences were found regarding patient and lesion characteristics. Perilesional hemorrhage occurred more frequently in older patients (p = 0.046) and in smaller lesions (p = 0.001). Hemoptysis was significantly more frequent in patients with perilesional hemorrhage (p = 0.01). Mean effective radiation dose in CBCT-CNB was 7.12 ± 8.78 mSv. Conclusions: CBCT-CNB combined with virtual guidance is a reliable and accurate technique that allows exact localization of pulmonary lesions, effective preprocedural planning and real-time fluoroscopy altogether.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2014

Ecological compensation: From general guidance and expertise to specific proposals for road developments

The main scientific bibliography addressing the rationale behind ecological compensation is reviewed in order to examine general guidelines. This contains interesting general guidance on how to implement compensation, and provides the basis for future developments in compensation practice. On this basis, we propose a further step in compensation practice, advancing compensation proposals or rules for specific kinds of projects and contexts, focusing on road projects in the Spanish Environmental Impact Assessment (EIA). Three main residual impacts of roads are identified which usually remain uncompensated for: the loss of natural and semi-natural land use, the increase in emissions resulting from any new road, and the fragmentation, severance or barrier effect on the landscape and its wildlife. To counteract these, four proposals, or “rules”, are advanced: conservation of natural and semi-natural land use area, conservation of dominant plant species physiognomy, compensation for emissions, and the rule of positive defragmentation. -- Highlights: • Ecological compensation theory does not specify guidelines for types of projects. • EIA practitioners lack valuable specific guidance on how to implement compensation. • Specific guidance for road project ecological compensation is proposed. • Compensation proposals should have in mind present-day compensation practice level. • Specific ways to compensate for habitat loss, emissions, and fragmentation are shown.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2016

Real-Time 3D Image Guidance Using a Standard LINAC: Measured Motion, Accuracy, and Precision of the First Prospective Clinical Trial of Kilovoltage Intrafraction Monitoring–Guided Gating for Prostate Cancer Radiation Therapy

Purpose: Kilovoltage intrafraction monitoring (KIM) is a new real-time 3-dimensional image guidance method. Unlike previous real-time image guidance methods, KIM uses a standard linear accelerator without any additional equipment needed. The first prospective clinical trial of KIM is underway for prostate cancer radiation therapy. In this paper we report on the measured motion accuracy and precision using real-time KIM-guided gating. Methods and Materials: Imaging and motion information from the first 200 fractions from 6 patient prostate cancer radiation therapy volumetric modulated arc therapy treatments were analyzed. A 3-mm/5-second action threshold was used to trigger a gating event where the beam is paused and the couch position adjusted to realign the prostate to the treatment isocenter. To quantify the in vivo accuracy and precision, KIM was compared with simultaneously acquired kV/MV triangulation for 187 fractions. Results: KIM was successfully used in 197 of 200 fractions. Gating events occurred in 29 fractions (14.5%). In these 29 fractions, the percentage of beam-on time, the prostate displacement was >3 mm from the isocenter position, reduced from 73% without KIM to 24% with KIM-guided gating. Displacements >5 mm were reduced from 16% without KIM to 0% with KIM. The KIM accuracy was measured at <0.3 mm in all 3 dimensions. The KIM precision was <0.6 mm in all 3 dimensions. Conclusions: Clinical implementation of real-time KIM image guidance combined with gating for prostate cancer eliminates large prostate displacements during treatment delivery. Both in vivo KIM accuracy and precision are well below 1 mm.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2014

SU-D-BRF-05: A Novel System to Provide Real-Time Image-Guidance for Intrauterine Tandem Insertion and Placement

Purpose: To develop a system that provides real-time image-guidance for intrauterine tandem insertion and placement for brachytherapy. Methods: The conceptualized system consists of an intrauterine tandem with a transparent, lensed tip, a flexible miniature fiber optic scope, light source and interface for CCD coupling. The tandem tip was designed to act as a lens providing a wide field-of-view (FOV) with minimal image distortion and focus length appropriate for the application. The system is designed so that once inserted, the image-guidance component of the system can be removed and brachytherapy can be administered without interfering with source transport or disturbing tandem placement. Proof-of-principle studies were conducted to assess the conceptualized system's (1) lens functionality (clarity, focus and FOV) (2) and ability to visualize the cervical os of a female placed in the lithotomy position. Results: A prototype of this device was constructed using a commercial tandem modified to incorporate a transparent tip that internally coupled with a 1.9mm diameter fiber optic cable. The 900mm-long cable terminated at an interface that provided illumination as well as facilitated visualization of patient anatomy on a computer. The system provided a 23mm FOV with a focal length of 1cm and provided clear visualization of the cervix, cervical fornix and cervical os. The optical components of the system are easily removed without perturbing the position of a tandem placed in a common fixation clamp. Conclusion: Clinicians frequently encounter difficulty inserting an intrauterine tandem through the cervical os, circumventing fibrotic tissue or masses within the uterus, and positioning the tandem without perforating the uterus. To mitigate these challenges, we have designed and conducted proof-of- principle studies to discern the utility of a prototype device that provides real-time image-guidance for intrauterine tandem placement using fiber optic components.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2014

SU-E-J-204: Radiation Dose to Patients Resulting From Image Guidance Procedures and AAPM TG-180 Update

Purpose: Image-guided radiation therapy (IGRT) is the new paradigm for patient positioning and target localization in radiotherapy. Daily imaging procedures add additional dose to the patient's treatment volume and normal tissues and may expose the organs at risk to unaccounted doses. This presentation is to update the progress of AAPM TG-180 which aims to provide strategies to quantify and account the dose from both MV and kV imaging in patient treatment planning. Methods: Our current knowledge on image guidance dose is presented. A summary of doses from image guidance procedures delivered to patients in relationship with therapeutic doses is given. Different techniques in reducing the image guidance dose are summarized. Typical organ doses resulting from different image acquisition procedures used in IGRT are tabulated. Results: Many techniques to reduce the imaging doses are available in clinical applications. There are large variations between dose to bone and dose to soft tissues for x-rays at kilovoltage energy range. Methods for clinical implementation of accounting for the imaging dose from an imaging procedure are available. Beam data from imaging systems can be generated by combining Monte Carlo simulations and experimental measurements for commissioning imaging beams in the treatment planning. Conclusion: The current treatment planning systems are not yet equipped to perform patient specific dose calculations resulting from kV imaging procedures. The imaging dose from current kV image devices has been significantly reduced and is generally much less than that resulting from MV. Because the magnitude of kV imaging dose is significantly low and the variation between patients is modest, it is feasible to estimate dose based on imaging producers or protocols using tabulated values which provides an alternative to accomplish the task of accounting and reporting imaging doses.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

The first clinical treatment with kilovoltage intrafraction monitoring (KIM): A real-time image guidance method

Purpose: Kilovoltage intrafraction monitoring (KIM) is a real-time image guidance method that uses widely available radiotherapy technology, i.e., a gantry-mounted x-ray imager. The authors report on the geometric and dosimetric results of the first patient treatment using KIM which occurred on September 16, 2014. Methods: KIM uses current and prior 2D x-ray images to estimate the 3D target position during cancer radiotherapy treatment delivery. KIM software was written to process kilovoltage (kV) images streamed from a standard C-arm linear accelerator with a gantry-mounted kV x-ray imaging system. A 120° pretreatment kV imaging arc was acquired to build the patient-specific 2D to 3D motion correlation. The kV imager was activated during the megavoltage (MV) treatment, a dual arc VMAT prostate treatment, to estimate the 3D prostate position in real-time. All necessary ethics, legal, and regulatory requirements were met for this clinical study. The quality assurance processes were completed and peer reviewed. Results: During treatment, a prostate position offset of nearly 3 mm in the posterior direction was observed with KIM. This position offset did not trigger a gating event. After the treatment, the prostate motion was independently measured using kV/MV triangulation, resulting in a mean difference of less than 0.6 mm and standard deviation of less than 0.6 mm in each direction. The accuracy of the marker segmentation was visually assessed during and after treatment and found to be performing well. During treatment, there were no interruptions due to performance of the KIM software. Conclusions: For the first time, KIM has been used for real-time image guidance during cancer radiotherapy. The measured accuracy and precision were both submillimeter for the first treatment fraction. This clinical translational research milestone paves the way for the broad implementation of real-time image guidance to facilitate the detection and correction of geometric and dosimetric errors, and resultant improved clinical outcomes, in cancer radiotherapy.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

SU-E-T-247: Determinations of the Optimal Phase for Respiratory Gated Radiotherapy From Statistical Analysis Using a Visible Guidance System

Purpose: Respiratory gated radiation therapy (RGRT) is used to minimize the radiation dose to normal tissue in lung cancer patients. Determination of the optimal point in the respiratory phase of a patient is important in RGRT but it is not easy. The goal of the present study was to see if a visible guidance system is helpful in determining the optimal phase in respiratory gated therapy. Methods: The breathing signals of 23 lung cancer patients were recorded with a Real-time Position Management (RPM) respiratory gating system (Varian, USA). The patients underwent breathing training with our visible guidance system, after which their breathing signals were recorded during 5 min of free breathing and 5 min of guided breathing. The breathing signals recorded between 3 and 5 min before and after training were compared. We performed statistical analysis of the breathing signals to find the optimal duty cycle in guided breathing for RGRT. Results: The breathing signals aided by the visible guidance system had more regular cycles over time and smaller variations in the positions of the marker block than the free breathing signals. Of the 23 lung cancer patients, 19 showed statistically significant differences by time when the values obtained before and after breathing were compared (p < 0.05); 30% and 40% of the duty cycle, respectively, was determined to be the most effective, and the corresponding phases were 30 60% (duty cycle, 30%; p < 0.05) and 30 70% (duty cycle, 40%; p < 0.05). Conclusion: Respiratory regularity was significantly improved with the use of the RPM with our visible guiding system; therefore, it would help improve the accuracy and efficiency of RGRT.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

Validation of a novel robot-assisted 3DUS system for real-time planning and guidance of breast interstitial HDR brachytherapy

Purpose: In current clinical practice, there is no integrated 3D ultrasound (3DUS) guidance system clinically available for breast brachytherapy. In this study, the authors present a novel robot-assisted 3DUS system for real-time planning and guidance of breast interstitial high dose rate (HDR) brachytherapy treatment. Methods: For this work, a new computer controlled robotic 3DUS system was built to perform a hybrid motion scan, which is a combination of a 6 cm linear translation with a 30° rotation at both ends. The new 3DUS scanner was designed to fit on a modified Kuske assembly, keeping the current template grid configuration but modifying the frame to allow the mounting of the 3DUS system at several positions. A finer grid was also tested. A user interface was developed to perform image reconstruction, semiautomatic segmentation of the surgical bed as well as catheter reconstruction and tracking. A 3D string phantom was used to validate the geometric accuracy of the reconstruction. The volumetric accuracy of the system was validated with phantoms using magnetic resonance imaging (MRI) and computed tomography (CT) images. In order to accurately determine whether 3DUS can effectively replace CT for treatment planning, the authors have compared the 3DUS catheter reconstruction to the one obtained from CT images. In addition, in agarose-based phantoms, an end-to-end procedure was performed by executing six independent complete procedures with both 14 and 16 catheters, and for both standard and finer Kuske grids. Finally, in phantoms, five end-to-end procedures were performed with the final CT planning for the validation of 3DUS preplanning. Results: The 3DUS acquisition time is approximately 10 s. A paired Student t-test showed that there was no statistical significant difference between known and measured values of string separations in each direction. Both MRI and CT volume measurements were not statistically different from 3DUS volume (Student t-test: p > 0.05) and they were significantly correlated to 3DUS measurement (Pearson test: MRI p < 0.05 and CT p < 0.001). The mean angular separation distance between catheter trajectories segmented from 3DUS and CT images was 0.42° ± 0.24°, while the maximum and mean trajectory separations were 0.51 ± 0.19 and 0.37 ± 0.17 mm, respectively. Overall, the new finer grid has performed significantly better in terms of dosimetric indices. The planning target volume dosimetric indices were not found statistically different between 3DUS and CT planning (Student t-test, p > 0.05). Both the skin and the pectoral muscle dosimetric indices were within ABS guidelines. Conclusions: A novel robot-assisted 3DUS system was designed and validated. To their knowledge, this is the first system capable of performing real-time guidance and planning of breast multicatheter HDR brachytherapy treatments. Future investigation will test the feasibility of using the system in the clinic and for permanent breast brachytherapy.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-G-BRA-03: PCA Based Imaging Angle Optimization for 2D Cine MRI Based Radiotherapy Guidance

Purpose: To develop an imaging angle optimization methodology for orthogonal 2D cine MRI based radiotherapy guidance using Principal Component Analysis (PCA) of target motion retrieved from 4DCT. Methods: We retrospectively analyzed 4DCT of 6 patients with lung tumor. A radiation oncologist manually contoured the target volume at the maximal inhalation phase of the respiratory cycle. An object constrained deformable image registration (DIR) method has been developed to track the target motion along the respiration at ten phases. The motion of the center of the target mass has been analyzed using the PCA to find out the principal motion components that were uncorrelated with each other. Two orthogonal image planes for cineMRI have been determined using this method to minimize the through plane motion during MRI based radiotherapy guidance. Results: 3D target respiratory motion for all 6 patients has been efficiently retrieved from 4DCT. In this process, the object constrained DIR demonstrated satisfactory accuracy and efficiency to enable the automatic motion tracking for clinical application. The average motion amplitude in the AP, lateral, and longitudinal directions were 3.6mm (min: 1.6mm, max: 5.6mm), 1.7mm (min: 0.6mm, max: 2.7mm), and 5.6mm (min: 1.8mm, max: 16.1mm), respectively. Based on PCA, the optimal orthogonal imaging planes were determined for cineMRI. The average angular difference between the PCA determined imaging planes and the traditional AP and lateral imaging planes were 47 and 31 degrees, respectively. After optimization, the average amplitude of through plane motion reduced from 3.6mm in AP images to 2.5mm (min:1.3mm, max:3.9mm); and from 1.7mm in lateral images to 0.6mm (min: 0.2mm, max:1.5mm), while the principal in plane motion amplitude increased from 5.6mm to 6.5mm (min: 2.8mm, max: 17mm). Conclusion: DIR and PCA can be used to optimize the orthogonal image planes of cineMRI to minimize the through plane motion during radiotherapy guidance.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

WE-H-207B-03: MRI Guidance in the Radiation Therapy Clinic: Site-Specific Discussions

In recent years, steady progress has been made towards the implementation of MRI in external beam radiation therapy for processes ranging from treatment simulation to in-room guidance. Novel procedures relying mostly on MR data are currently implemented in the clinic. This session will cover topics such as (a) commissioning and quality control of the MR in-room imagers and simulators specific to RT, (b) treatment planning requirements, constraints and challenges when dealing with various MR data, (c) quantification of organ motion with an emphasis on treatment delivery guidance, and (d) MR-driven strategies for adaptive RT workflows. The content of the session was chosen to address both educational and practical key aspects of MR guidance. Learning Objectives: Good understanding of MR testing recommended for in-room MR imaging as well as image data validation for RT chain (e.g. image transfer, filtering for consistency, spatial accuracy, manipulation for task specific); Familiarity with MR-based planning procedures: motivation, core workflow requirements, current status, challenges; Overview of the current methods for the quantification of organ motion; Discussion on approaches for adaptive treatment planning and delivery. T. Stanescu - License agreement with Modus Medical Devices to develop a phantom for the quantification of MR image system-related distortions.; T. Stanescu, N/A.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

Guidance for Developing Principal Design Criteria for Advanced (Non-Light Water) Reactors

In July 2013, the US Department of Energy (DOE) and US Nuclear Regulatory Commission (NRC) established a joint initiative to address a key portion of the licensing framework essential to advanced (non-light water) reactor technologies. The initiative addressed the “General Design Criteria for Nuclear Power Plants,” Appendix A to10 Code of Federal Regulations (CFR) 50, which were developed primarily for light water reactors (LWRs), specific to the needs of advanced reactor design and licensing. The need for General Design Criteria (GDC) clarifications in non-LWR applications has been consistently identified as a concern by the industry and varied stakeholders and was acknowledged by the NRC staff in their 2012 Report to Congress1 as an area for enhancement. The initiative to adapt GDC requirements for non-light water advanced reactor applications is being accomplished in two phases. Phase 1, managed by DOE, consisted of reviews, analyses and evaluations resulting in recommendations and deliverables to NRC as input for NRC staff development of regulatory guidance. Idaho National Laboratory (INL) developed this technical report using technical and reactor technology stakeholder inputs coupled with analysis and evaluations provided by a team of knowledgeable DOE national laboratory personnel with input from individual industry licensing consultants. The DOE national laboratory team reviewed six different classes of emerging commercial reactor technologies against 10 CFR 50 Appendix A GDC requirements and proposed guidance for their adapted use in non-LWR applications. The results of the Phase 1 analysis are contained in this report. A set of draft Advanced Reactor Design Criteria (ARDC) has been proposed for consideration by the NRC in the establishment of guidance for use by non-LWR designers and NRC staff. The proposed criteria were developed to preserve the underlying safety bases expressed by the original GDC, and recognizing that advanced reactors may take advantage of various new passive and inherent safety features different from those associated with LWRs.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

A Qualitative Assessment of Current CCF Guidance Based on a Review of Safety System Digital Implementation Changes with Evolving Technology

The US Nuclear Regulatory Commission (NRC) is initiating a new rulemaking project to develop a digital system common-cause failure (CCF) rule. This rulemaking will review and modify or affirm the NRC's current digital system CCF policy as discussed in the Staff Requirements Memorandum to the Secretary of the Commission, Office of the NRC (SECY) 93-087, Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light Water Reactor (ALWR) Designs, and Branch Technical Position (BTP) 7-19, Guidance on Evaluation of Defense-in-Depth and Diversity in Digital Computer-Based Instrumentation and Control Systems, as well as Chapter 7, Instrumentation and Controls, in NRC Regulatory Guide (NUREG)-0800, Standard Review Plan for Review of Safety Analysis Reports for Nuclear Power Plants (ML033580677). The Oak Ridge National Laboratory (ORNL) is providing technical support to the NRC staff on the CCF rulemaking, and this report is one of several providing the technical basis to inform NRC staff members. For the task described in this report, ORNL examined instrumentation and controls (I&C) technology implementations in nuclear power plants in the light of current CCF guidance. The intent was to assess whether the current position on CCF is adequate given the evolutions in digital safety system implementations and, if gaps in the guidance were found, to provide recommendations as to how these gaps could be closed.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2017

NSRD-10: Leak Path Factor Guidance Using MELCOR

Estimates of the source term from a U.S. Department of Energy (DOE) nuclear facility requires that the analysts know how to apply the simulation tools used, such as the MELCOR code, particularly for a complicated facility that may include an air ventilation system and other active systems that can influence the environmental pathway of the materials released. DOE has designated MELCOR 1.8.5, an unsupported version, as a DOE ToolBox code in its Central Registry, which includes a leak-path-factor guidance report written in 2004 that did not include experimental validation data. To continue to use this MELCOR version requires additional verification and validations, which may not be feasible from a project cost standpoint. Instead, the recent MELCOR should be used. Without any developer support and lack of experimental data validation, it is difficult to convince regulators that the calculated source term from the DOE facility is accurate and defensible. This research replaces the obsolete version in the 2004 DOE leak path factor guidance report by using MELCOR 2.1 (the latest version of MELCOR with continuing modeling development and user support) and by including applicable experimental data from the reactor safety arena and from applicable experimental data used in the DOE-HDBK-3010. This research provides best practice values used in MELCOR 2.1 specifically for the leak path determination. With these enhancements, the revised leak-path-guidance report should provide confidence to the DOE safety analyst who would be using MELCOR as a source-term determination tool for mitigated accident evaluations.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗