ML17276B191
| ML17276B191 | |
| Person / Time | |
|---|---|
| Issue date: | 10/03/2017 |
| From: | Matthew Hiser, Amy Hull, Pat Purtscher, Ramuhalli P, Robert Tregoning Office of Nuclear Regulatory Research, Pacific Northwest National Laboratory |
| To: | |
| Matthew Hiser | |
| References | |
| Download: ML17276B191 (1) | |
Text
Harvesting of Aged Materials from Operating and Decommissioning Nuclear Power Plants M. Hisera, P. Purtschera, P. Ramuhallib, A. B. Hulla, and R. Tregoninga aU.S. Nuclear Regulatory Commission (NRC), Washington, D.C., USA bPacific Northwest National Laboratory (PNNL), Richland, WA, USA Background and Motivation
- Recent developments in the nuclear industry include stronger interest in extended plant operation and plans to shut down a number of nuclear power plants (NPPs). In the U.S., Potential Criteria for Harvesting Prioritization there is strong interest in extending NPP lifespans through subsequent license renewal (SLR) A number of criteria may be considered when prioritizing the data from 60 to 80 years. needs for harvesting, including:
- Applicability of harvested material for addressing critical gaps
- Extended plant operation and SLR raise a number of technical issues that may require further research to understand and quantify aging mechanisms. U.S. utilities and the U.S. - Harvesting for critical gaps prioritized over less essential Nuclear Regulatory Commission (NRC) have focused on the aging of systems, structures, and technical gaps.
components and in particular four key SLR issues: reactor pressure vessel (RPV)
- Ease of laboratory replication of the degradation scenario embrittlement, irradiation-assisted stress corrosion cracking of reactor internals, concrete - For example, simultaneous thermal and irradiation structures and containment degradation, and electrical cable qualification and condition conditions are difficult to replicate, and accelerated aging assessment. may not be feasible for a mechanism sensitive to dose rate.
- Meanwhile, in recent years, a number of NPPs, both in the U.S. and internationally, have
- Unique field aspects of degradation shut down or announced plans to shut down for various reasons, including economic, - For example, unusual operating experience or legacy materials (fabrication methods, etc.) no longer available.
political, and technical challenges. Unlike in the past when there were very few plants
- Fleet-wide vs. plant-specific applicability of data shutting down, these new developments provide opportunities for harvesting components that were aged in representative light water reactor (LWR) environments. - Greater value in addressing an issue applicable to a larger number of plants.
- In a third related development, economic challenges and limited budgets have restricted
- Harvesting cost and complexity the resources available to support new research, including harvesting programs. Given this - For example, harvesting un-irradiated concrete or electrical cables less expensive and less complex than constrained budget environment, aligning interests and leveraging with other organizations harvesting from the reactor internals or RPV.
is important to allow maximum benefit and value for future research programs.
- Availability of reliable in-service inspection (ISI) techniques for the material / component Current Activities - If mature inspection methods exist and are easy to apply, harvesting may be less valuable.
- NRC has recently undertaken an effort, with
- Availability of materials for harvesting the assistance of Pacific Northwest National
- Timeliness of the expected research results relative to the objective.
Laboratory (PNNL), to develop a strategic approach to harvesting aged materials from The above potential criteria provide a systematic approach to prioritize data needs for harvesting. Different NPPs. Due to limited opportunities, past organizations may weigh and consider each of these criteria differently based on their interests and perspectives, but harvesting efforts have been reactive to each criterion is likely relevant to some degree for any organization. NRC is interested in engaging with other individual plants shutting down and beginning organizations to prioritize data needs for harvesting and identify areas of common interest.
decommissioning. Given the expected availability of materials from numerous plants Harvesting Database and anticipated research needs to better
- The NRC is pursuing the development of a database for sources of materials for harvesting, which could include understand aging out to 80 years of operation, the NRC is pursuing a more proactive approach both previously harvested materials and those available for future harvesting. This database would allow for to prioritize the data needs best addressed by aligning of high-priority data needs to the available sources of materials. The level of detail for the database harvesting and identify the best sources of should be appropriate for the factors influencing decision-making. NRC is interested in engaging with other materials to address high-priority data needs organizations in developing the database.
for regulatory research.
- The first step in this strategic approach is to Path Forward prioritize data needs for harvesting. A data
- NRCs experience is that harvesting can yield highly representative and valuable data on materials aging, but these need describes a particular degradation scenario and should be defined with as much efforts will be challenging. Having a clearly defined objective and early engagement with other stakeholders are detail as appropriate in terms of the material keys to success. As specific harvesting opportunities are identified through this strategic approach, the NRC (alloy, composition, etc.) and environment welcomes opportunities for cooperation and leveraging of resources with other interested research organizations.
(temperature, fluence, chemistry, etc.).