At Oak Ridge National Laboratory’s (ORNL) High Flux Isotope Reactor (HFIR), we generate the nation’s highest continuous flux of thermal neutrons for materials research and isotope production. As an advanced user facility stewarded by the US Department of Energy (DOE)’s Office of Basic Energy Sciences (BES), HFIR provides hundreds of researchers each year with access to cutting-edge capabilities in neutron scattering, isotope production, materials irradiation, and materials activation. Many of our stakeholders rely on these capabilities to provide critical information and products for missions in scientific research, technology development, health care and national security. The purpose of this message is to communicate to you what has been happening at HFIR since we recently shut the reactor down and what our plans are for resuming operations.
First some background information. HFIR operates for 7 cycles a year, each cycle requiring a new fuel element and lasting around 24 days. Each fuel element consists of hundreds of fuel plates that are fabricated and then assembled and welded into a cylindrical assembly that allows cooling water to flow through. In November 2018, operators at HFIR manually shut the reactor down during a cycle and placed it in a safe condition in response to elevated radiation readings within the primary system that cools the reactor core. No personnel were injured or exposed to unusual levels of radiation either within the HFIR facility or on the ORNL campus. No radioactive contamination was noted internal or external to the HFIR facility due to this event. There was never any danger to the public. Upon examination, it was determined that several of the fuel plates that make up the fuel element had deflected away from their normal positions. This likely led to the elevated radiation readings in the primary cooling system. 
DOE has since been conducting an independent review to identify the cause of this issue and to recommend corrective actions to prevent it from happening again. At the same time, ORNL and the company that manufactures HFIR fuel are working closely together to proactively review the issue. ORNL is working on a corrective action plan to improve alignment between design and fuel element manufacturing and to put in place new and more rigorous approaches to fuel element inspection. Our priority is to ensure the future operation of HFIR with the highest level of confidence in safety and reliability. 
We understand that many of you depend on the capabilities provided by HFIR and are eager to know when it will resume operations. A general overall approach has been agreed upon with DOE and will be worked out in detail over the next few weeks. We expect that within the month we will be able to provide an estimated timeline for resuming HFIR operations. We understand and apologize for the impact this interruption is having on your activities and we will keep you informed of progress. - Paul Langan