ML18130A855
| ML18130A855 | |
| Person / Time | |
|---|---|
| Issue date: | 06/19/2018 |
| From: | Michael Cheok NRC/RES/DRA/PRB |
| To: | Weber M Office of Nuclear Regulatory Research |
| Shared Package | |
| ML18130A854 | List: |
| References | |
| Download: ML18130A855 (2) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 19, 2018 MEMORADUM TO: Michael F. Weber 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 2017 ANNUAL REPORT This memorandum transmits the Accident Sequence Precursor (ASP) Program 2017 Annual Report. The ASP Program assesses licensee event reports at U.S nuclear power plants to identify potential precursors to core damage.
Thirteen events were determined to exceed the ASP Program threshold and, therefore, are precursors. Of these 13 precursors, 8 events were identified by ASP analyses and 5 events used Significance Determination Process results. No significant precursors were identified in 2017.
A review of the trends over the past decade (2008-2017) reveals statistically significant decreasing trends for all precursors, precursors due to degraded conditions, and precursors at pressurized-water reactors. Since 2008, the ASP Program has documented 149 precursors (99 involving degraded conditions and 50 resulting from initiating events). Emergency power system failures are the most frequent cause of degraded condition precursors, while 34 percent of initiating event precursors are the result of natural phenomena (e.g., severe weather, seismic, etc.).
The ASP Program results show that current agency oversight programs and licensing activities remain effective. The Reactor Oversight Process (ROP) continues to focus on plant events based on safety significance, and ASP events and trends do not show gaps in licensee performance areas not currently covered by the ROP. 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 show indications of increasing risk due to the potential cumulative impact of risk-informed initiatives.
Enclosure:
As stated CONTACT: Ian Gifford, RES/DRA/PRB 301-415-3256
ML18130A854 OFFICE RES/DRA/PRB RES/DRA/PRB RES/DRA/PRB RES/DRA NAME I. Gifford C. Hunter A. Gilbertson M. Cheok (via email)
DATE 5/11/2018 5/11/2018 5/11/2018 6/19/18