ML20049G013
| ML20049G013 | |
| Person / Time | |
|---|---|
| Issue date: | 02/24/2020 |
| From: | Michael Cheok NRC/RES/DRA |
| To: | Raymond Furstenau Office of Nuclear Regulatory Research |
| C. Hunter 415-1394 | |
| Shared Package | |
| ML20049G011 | List: |
| References | |
| Download: ML20049G013 (2) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 24, 2020 MEMORADUM TO: Raymond V. Furstenau Director of Nuclear Regulatory Research FROM: Michael C. Cheok, Director /RA/
Division of Risk Analysis Office of Nuclear Regulatory Research
SUBJECT:
TRANSMITTAL OF THE ACCIDENT SEQUENCE PRECURSOR PROGRAM 2019 ANNUAL REPORT This memorandum transmits the Accident Sequence Precursor (ASP) Program 2019 Annual Report. The ASP Program assesses licensee event reports (LERs) at U.S. nuclear power plants to identify potential precursors to core damage. In addition, an updated ASP Program Summary Description is also enclosed. This report provides background and ASP process information, most of which used to be contained in the annual ASP Program reports. This separate report can be used as reference to allow the focus of the annual reports to be on the updated ASP Program results, trends, and insights.
Two events were determined to exceed the ASP Program threshold and, therefore, are precursors. Both precursors were identified by independent ASP analyses. This annual precursor count is a historic low. In addition, the number of LERs issued and those identified as potential precursors are at historically low levels. No significant precursors were identified in 2019. In addition, no precursors with a conditional core damage probability or increase in core damage probability greater than or equal to 10-5 were identified (for the second year in a row).
A review of the trends over the past decade (2010-2019) reveals statistically significant decreasing trends for all precursors and most precursors subgroups (e.g., higher-risk precursors initiating events, degraded conditions, losses of offsite power, precursors at pressurized-water reactors, etc.). However, no statistically significant trends were identified for precursors at boiling-water reactors and emergency diesel generator degraded conditions during this same period.
The decreasing 10-year precursor trends, along with the decreasing overall risk from precursors as shown in the integrated ASP index, demonstrate that current agency oversight programs and licensing activities remain effective. A review of precursor data and trends do not reveal any gaps in licensee performance areas not currently covered by the Reactor Oversight Process. The ASP Program results also continue to show that licensee risk management initiatives are effective in helping to maintain a flat or decreasing risk profile for the industry. In the area of licensing activities, the risk profiles and trends from the ASP Program do not indicate an increase in risk due to the potential cumulative impact of risk-informed initiatives.
Enclosure:
As stated CONTACT: Christopher Hunter, RES/DRA/PRB 301-415-1394
ML20049G011 OFFICE RES/DRA/PRB RES/DRA/PRB RES/DRA NAME C. Hunter J. Nakoski M. Cheok DATE 02/20/20 02/20/20 02/24/20