June 7, 2010
Recent interruption of testing at the ATR demonstrates conservative operational practice
On May 30, 2010, Idaho National Laboratory voluntarily interrupted routine testing at the Advanced Test Reactor because operators detected momentary, higher-than-normal radioactivity levels in the reactor's primary coolant and building exhaust systems. This conservative action followed established procedures to proactively interrupt operation of the reactor well before radioactivity levels could pose any risk to employees or the public.
The radioactivity levels detected were too low to trigger any routine reporting criteria, but warranted interruption of testing at the ATR to allow for experiment analysis and removal of the source. No measurable exposure to workers or the public occurred.
One of the ATR's functions as a test reactor is to test how new nuclear fuel designs perform. During this testing, experiments may release minor quantities of radioactivity into the reactor's primary coolant system. INL's continuous monitoring of ATR systems quickly detects such release conditions, should they occur.
INL is disseminating this information to demonstrate ATR's detection and safety procedures. The decision to interrupt testing was not based on any safety requirement but on good operational practice to minimize radioactivity in the primary coolant system. This simplifies conduct of future maintenance activities and keeps exposures to workers in the plant as low as reasonably achievable.
"To assure the reactor’s continued ability to safely carry out its essential work, it is monitored and maintained with discipline," said INL Laboratory Director John Grossenbacher. "The Advanced Test Reactor is, without question, one of the most capable test reactors in the world. We welcome every opportunity we get to inform the public about its innovative design, operating record and the vital service it provides to our nation."
ATR staff has now determined that the experiment which released fission products into the reactor coolant is one of several testing new types of low-enriched fuel that could be used in research reactors that currently run on highly-enriched uranium. Testing at the ATR will resume after the experiment causing the increased radioactivity is removed and normal scheduled maintenance work is completed.