ML18151A989
| ML18151A989 | |
| Person / Time | |
|---|---|
| Issue date: | 05/31/2018 |
| From: | Michael Layton Division of Spent Fuel Management |
| To: | Michael Case NRC/RES/DSA |
| Barto A | |
| References | |
| Download: ML18151A989 (4) | |
Text
May 31, 2018 MEMORANDUM TO: Michael J. Case, Director Division of Systems Analysis Office of Nuclear Regulatory Research FROM: Michael C. Layton, Director /RA/
Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
RESEARCH ASSISTANCE REQUEST: RADIOCHEMICAL ASSAY MEASUREMENTS OF HBU FUEL STORAGE DEMONSTRATION PROJECT SISTER RODS, AND UPDATING NUREG/CR-7108 AND NUREG/CR-7109 The Office of Nuclear Material Safety and Safeguards (NMSS) requests assistance from the Office of Nuclear Regulatory Research (RES) to extend experiments under the U.S. Department of Energys (DOEs) Office of Nuclear Energy (NE), Spent Fuel and Waste and Science and Technology (SFWST) program to characterize and test spent fuel rods. Any data obtained from measurements will be used to update NUREG/CR-7108, An Approach for Validating Actinide and Fission Product Burnup Credit Criticality Safety AnalysesIsotopic Composition Predictions (Agencywide Documents Access and Management System (ADAMS) Accession Number ML12116A124). NUREG/CR-7109, An Approach for Validating Actinide and Fission Product Burnup Credit Criticality Safety AnalysesCriticality (keff ) Predictions (ADAMS Accession No. ML12116A128), will be updated in parallel for new cross section data.
The scope, described below, has been discussed with NMSS and RES staff. RES staff agrees the scope is achievable and is working to identify the best approach to accomplish the work.
This work falls under regulatory research area criticality safety, as per the Division of Spent Fuel Management (DSFM) Super User Need (ADAMS Accession No. ML17018A098). This emergent need will be added to the Super User Need during the next renewal period of the document.
Background:
The purpose of the SFWST program is to establish baseline and fundamental understanding (e.g., initial characteristics, mechanical performance, and conditions) of fuel assemblies for the DOE-Industry High Burnup Confirmatory Data Project. This DOE program will be extended to support evaluation and potential reductions in depletion code validation uncertainty by obtaining data on the isotopic composition of various spent fuel samples of sister rod material.
CONTACT: Andrew Barto, NMSS/DSFM 301-415-6941
M. Case 2 Regulatory Application:
The work requested will support the U.S. Nuclear Regulatory Commission (NRC) with criticality safety analyses for fissile materials systems in Title 10 of the Code of Federal Regulations (10 CFR) Part 71, Packaging and Transportation of Radioactive Material, and 10 CFR Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater Than Class C Waste. This work will also support NRC evaluations in support of the industrys effort to move towards higher burnup fuels, which results in longer average assembly depletion.
Updating NUREG/CR-7108 and NUREG/CR-7109 will allow applicants and licensees to more easily use new cross section data, with potential reduced uncertainties associated with depletion validation. Applicants and licensees using the recommended values from the revised NUREG/CR validation analyses (similar to what was recommended in Interim Staff Guidance-8, Revision 3, Burnup Credit in the Criticality Safety Analyses of PWR Spent Fuel in Transportation and Storage Casks (ADAMS Accession No. ML12261A433)), as opposed to performing their own system-specific validation analysis, will benefit from more efficient reviews due to fewer anticipated requests for additional information related to validation. As a result, less staff time will be devoted to burnup credit criticality reviews.
Technical Issue:
Radiochemical analyses (RCAs) provide measured isotopic compositions of commercial spent nuclear fuel to support depletion code and nuclear data validation. For independent validation of depletion methods and data, calculated isotopic predictions have traditionally been compared to RCA data to determine biases and uncertainties for each isotope considered in the safety evaluation. For isotopes with relatively few measurements, the uncertainty can be large--
decreasing the benefits of high fidelity depletion analyses. Accurate predictions of the isotopic compositions are the foundational element for all applications that involve spent fuel (e.g.,
thermal analyses, radiation dose analyses, and criticality safety). The current available data for pressurized water reactor (PWR) isotopic validation is based on 76 samples with measured major actinides and varying numbers of minor actinides and fission products. The primary objective of this work is to determine if measurements of sister rod material can fill gaps in the existing RCA database, thereby reducing the uncertainty associated with isotopic depletion code modeling of spent nuclear fuel.
Tasks:
NMSS requires assistance in understanding gaps in the existing RCA database, and options available to either fill in or mitigate the impacts of these gaps. NMSS also requests assistance with updates to NUREG/CR-7108 and NUREG/CR-7109, using the validation techniques detailed in those reports, for ENDF/B-VII.1 and ENDF/B-VIII.0 cross section data.
The work will be accomplished in three tasks:
- 1. Evaluate existing PWR RCA data set for gaps, and determine if sister rod data can fill these gaps in order to reduce uncertainties associated with PWR isotopic depletion validation for spent fuel burnup credit criticality analyses. The result of this task should be a whitepaper, which documents gaps in the depletion validation data set, determines the optimum number and type of sister rod RCA measurements to add to or replace existing measurements, and estimates the potential depletion validation bias and bias uncertainty reductions from including new measurements. This paper should also estimate the costs of any proposed measurement program.
M. Case 3
- 2. Perform the RCA measurements recommended in Task 1. The performance of this task will depend on the recommendations from Task 1, and will depend on the overall estimated cost of the measurement program, as well as available NRC funding to perform the measurements. A measurement program will be pursued by the NRC if the potential benefit from uncertainty reduction outweighs the estimated costs of the program. Task 3 can proceed regardless of whether or not new measurements are included.
- 3. Using the expanded data set from Task 2, update the validation analysis performed in NUREG/CR-7108 for ENDF/B-VII.1 and -VIII.0 data. If new RCA measurements are recommended in Task 1 and performed in Task 2, this work should also update the bias and bias uncertainty estimates for ENDF/B-V and -VII.0 data from NUREG/CR-7108. In parallel with updating NUREG/CR-7108, this task includes updating NUREG/CR-7109 on criticality validation using new cross section data in ENDF/B-VII.1 and -VIII.0.
Deliverables:
Title Due Date Issue a whitepaper with detailed recommendations for RCA measurement 10/2018 program, and estimated costs Issue NUREG/CR: Evaluation of sister rod RCA measurements for use in 6/2020 spent nuclear fuel isotopic depletion code validation Issue NUREG/CR: Updated PWR spent fuel isotopic depletion and 3/2021 criticality validation for ENDF/B-VII.1 and -VIII.0 data Estimated Resources:
FY18 FY19 FY20 FY21
$90 K/0.1 FTE $400 K/0.1 FTE $400 K/0.2 FTE $100 K/0.2 FTE Priority: 3
ML18151A989 OFFICE NMSS/SFM NMSS/SFM Tech. Ed. NMSS/SFM NAME ABarto TTate LMoorin MLayton DATE 5/31/2018 5 /31/2018 5 /31/2018 5 /31/2018