ML17223A716
| ML17223A716 | |
| Person / Time | |
|---|---|
| Issue date: | 08/22/2017 |
| From: | Michael Case NRC/RES/DSA |
| To: | Mirela Gavrilas Office of Nuclear Reactor Regulation |
| Yarsky P | |
| Shared Package | |
| ML17223A713 | List: |
| References | |
| NRR-2015-010 | |
| Download: ML17223A716 (3) | |
Text
OFFICIAL USE ONLY - PREDECISIONAL INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 August 22, 2017 MEMORANDUM TO: Mirela Gavrilas, Director Division of Safety Systems Office of Nuclear Reactor Regulation FROM: Michael J. Case, Director /RA/
Division of Systems Analysis Office of Nuclear Regulatory Research
SUBJECT:
TRANSMITTAL OF PRELIMINARY, INTERIM ANALYSIS OF KATHY ATWS-I EXPERIMENTAL DATA (NRR-2015-010)
By memorandum dated August 17, 2015 (ADAMS Accession No. ML15125A219), the Office of Nuclear Reactor Regulation (NRR) requested that the Office of Nuclear Regulatory Research (RES) to continue the development and benchmarking of TRACE with state-of-the-art, realistic modeling capabilities with relevant, full-scale data; thereby enabling the continued use of confirmatory calculations in NRRs licensing reviews. This request relates to previously conducted confirmatory analyses of anticipated transient without SCRAM (ATWS) scenarios, which concluded that there are physical processes that can lead to fuel damage during postulated ATWS scenarios where large amplitude power/flow instabilities occur (i.e., ATWS-I events) under certain circumstances. These circumstances are beyond where plants are currently allowed to operate. However, maximum extended load line limit analysis plus (MELLLA+) or extended flow window (EFW) operation can exacerbate the consequences of ATWS events compared to plants operating at lower core power-to-flow ratios. We have previously been tasked by your office to provide confirmatory analyses of such events using our TRACE code. RES responded to the request via memorandum dated September 4, 2015 (ADAMS Accession No. ML15237A326).
RES has conducted a preliminary analysis of the test data with regards to the conditions under failure to rewet was observed during the experimental campaign. The purpose of the preliminary analysis is to document initial observations and interim recommendations for NRRs purposes as they relate to licensing reviews. The conclusions of the RES preliminary analysis are subject to change based on the more detailed and thorough evaluation of the experimental data that is an on-going effort of the current user need. The RES staffs preliminary analysis report is enclosed with this memorandum as Enclosure 1.
We provided a draft of this report to your staff on May 19, 2017 and responded to your staffs comments on the draft report on May 24, 2017. In order to better respond to some of these comments, RES scheduled a briefing with your staff to discuss resolution of several comments on June 6, 2017. During that meeting the RES and NRR staff agreed to make several revisions Enclosure transmitted herewith contains CONTACT: Peter Yarsky, RES/DSA/CRAB Official Use Only - Predecisional (301) 415-2384 Information. When separated from enclosure this transmittal document is decontrolled.
OFFICIAL USE ONLY - PREDECISIONAL INFORMATION
OFFICIAL USE ONLY - PREDECISIONAL INFORMATION M. Gavrilas 2 to the report to address the comments. The RES staff revised the report and provided a new draft to NRR on July 20, 2017. We received additional comments from your staff on August 8, 2017. We revised the report again in response to these comments, but were not able to resolve all of the new issues raised in the recent comments (e.g., describing, in detail, the two-phase flow and fuel thermal-mechanical mechanisms on a local basis affecting the failure to rewet incidence). These issues will be addressed by the RES staffs on-going analysis. In discussing this further with your staff via e-mail correspondence we agreed to proceed with providing the preliminary analysis noting that the findings are subject to change and that the recommendations included in the report are interim until the RES staffs final analysis can be completed. With this clarification, NRR agreed that we should proceed with providing the preliminary report.
We look forward to our continued collaboration on the remaining tasks under this user need.
Enclosure:
- 1. Yarsky, P., Preliminary Analysis of Karlstein Thermal Hydraulic Test Facility (KATHY)
Anticipated Transient without SCRAM with Instability (ATWS-I) Temperature Test Data, August 9, 2017.
OFFICIAL USE ONLY - PREDECISIONAL INFORMATION
ML17223A713 OFFICE RES/DSA/CRAB RES/DSA/CRAB RES/DSA BC:RES/DSA/CRAB D:RES/DSA NAME PYarsky TZaki SBajorek CHoxie MCase DATE 7/28/17 7/28/17 8/9/17 7/28/17 8/22/17