The DOE Unreviewed Safety Question Process, Addressing New Information For Credible Nuclear Accidents
The Department of Energy (DOE) Unreviewed Safety Question (USQ) process is in use for hazardous nuclear facilities operated within the DOE nuclear complex. DOE, which is the federal nuclear safety regulator for its nuclear facilities, requires that each nuclear facility have a Documented Safety Analysis that defines the controls for each credible accident based on a detailed accident analysis. The DOE USQ process provides key mechanisms for formally identifying to the regulator potential accident analysis issues at operating nuclear facilities including those that stem from emergent or new information on hazards. The DOE USQ process provides for formal evaluation of those emergent issues and for determining the need for formal regulator (DOE) review and approval of any resulting immediate or long-term actions. Regarding the March 2011 accident at the Fukushima Daiichi Nuclear Power Station, lessons learned on the evaluation and disposition of new information have been noted by the Institute of Nuclear Power Operations (INPO) and the National Research Council. These organizations noted that: - when new information indicates the potential for conditions that could significantly reduce safety margins or exceed current design assumptions, a timely, formal, and comprehensive assessment of the potential for substantial consequences should be conducted, and - if the new information analysis results in substantial changes to the risk profile or could impact the function of important safety systems, then compensatory actions or countermeasures need to be established without delay. The objective of this paper is to raise awareness regarding the salient requirements and guidance of the DOE USQ process used at DOE's operating nuclear facilities that bear on handling of emergent or new information on hazards and that address the lessons learned noted above by INPO and the National Research Council. There is no analysis or intent to make any implications regarding how use of the DOE USQ process might have affected events at Fukushima. The DOE USQ process, when applied as intended at DOE nuclear facilities, addresses lessons learned identified by INPO and the National Research Council regarding use of emergent or new information on hazards. The DOE USQ process ensures a timely, formal, and comprehensive assessment of the potential for substantial consequences resulting from new information on hazards. When the new information analysis results in substantial changes to the risk profile or shows an impact to the function of important safety systems, the DOE USQ process calls for compensatory actions or countermeasures to be established in a timely manner. The DOE USQ process ensures a formal evaluation by the regulator and approval of the planned actions addressing the vulnerabilities made know by new information on hazards. (authors)