DEFENSE NUCLEAR FACILITIES SAFETY BOARD

February 2, 2024

TO: Katherine R. Herrera, Acting Technical Director

FROM: Frank Harshman and Clinton Jones, Resident Inspectors

SUBJECT: Oak Ridge Activity Report for Week Ending February 2, 2024

Building 9212: CNS was performing a functional test of the level detection system for the 

secondary cyclone separators and bag filter tank trap on the building’s dry vacuum system when 

the level transmitter failed to actuate, resulting in a failure of the surveillance. The building’s 

shift manager was notified, who then declared the system inoperable and entered the limiting 

condition for operation (LCO) due to the surveillance requirement not being met. CNS reported 

an occurrence for a failure of a safety significant system to perform its designed safety function. 

CNS placed the system into warm standby mode to prevent exceeding the time limits of the 

action statement of the LCO while CNS works towards repairing the transmitter. The resident 

inspector attended the event investigation. One resultant action of note was the action of 

Reliability Engineering to perform an evaluation to determine the cause of the failure, whether 

other failures are related (see 7/17/2020 report), and to evaluate the overall reliability of the dry 

vacuum level detection system. 

Special Nuclear Material Vehicle (SNMV): CNS declared a potential inadequacy in the safety 

analysis (PISA) when it was discovered the SNMV safety basis does not address the criticality 

safety control for neutron poisons as required. CNS utilizes neutron poisons in the rackable can 

storage boxes, which are regularly shipped on-site between buildings. The SNMV criticality 

safety evaluation assumes that the same configuration for the containers is maintained during 

shipping and therefore does not require any additional controls. However, the sitewide criticality 

control review criteria requires controls associated with neutron poison to be elevated to the 

safety basis. As a result of this requirement, a PISA was determined to exist. CNS determined 

that no operational restrictions are required due to the implementation of container controls in the 

shipping and receiving buildings. 

Conduct of Operations: The RI attended one of the new Trend Analysis and Problem 

Prevention (TAPP) meetings. This meeting is based on a charter that was developed as part of 

the actions of the revised Conduct of Operations Continuum Plan that was issued in December of 

2023. As an effort to maintain accountability, the TAPP team will define tracking methods and 

potential reporting metrics for the visible leadership floor/field observation time using guidelines 

from the charter. During this meeting, the TAPP team discussed trends from the issues 

management board, nuclear criticality safety issues, disciplined operations observations, and 

both NPO and DNFSB observations. The notable item of interest was a demonstration of a 

search algorithm that could be used in certain databases within the contractor assurance system 

to identify similarities in issues based on key words. The algorithm appeared to be efficient, 

running quickly despite the large dataset it analyzed, and returned a score next to the results 

giving indication of the level of similarity to the key words. The TAPP team is engaged with the 

developer to further enhance the algorithm’s use. In the resident inspector’s opinion, this tool 

has the ability to significantly enhance CNS’s ability to reduce recurrence of issues by instituting 

effective corrective actions.