DEFENSE NUCLEAR FACILITIES SAFETY BOARD

January 26, 2024

TO: Katherine R. Herrera, Acting Technical Director

FROM: A. Holloway and C. Stott, Resident Inspectors

SUBJECT: Pantex Plant Activity Report for Week Ending January 26, 2024

Staff Activity: C. Berg joined the resident inspectors to assess a nuclear explosive safety (NES) 

change evaluation, attend a training course, and walkdown facilities to assess fire protection 

system configurations. C. Stott traveled to Albuquerque, NM, to attend a training course.

Nuclear Explosive Safety: A NES study group convened this week to evaluate recovery 

activities for a nuclear explosive in a facility with water intrusion underneath the electrostatic 

dissipative flooring (see 12/08/23 report). CNS asserted that the dissipative functionality of the 

flooring could not be verified through testing; therefore, it cannot be credited within the safety 

basis to perform its safety function. The project team proposed a nuclear explosive engineering 

procedure that permitted partial assembly of the nuclear explosive—to a transportable 

configuration—and subsequent removal from the facility. The study group, project team, and 

Board’s staff observed the proposed operations in a training environment. These particular 

assembly operations are currently not authorized at Pantex. The Board’s staff questioned the 

proposed use of a localized electrostatic dissipative environment and the potential for unanalyzed 

electrostatic discharge hazards. In addition to this topic, the study group also discussed the use 

of procedural line throughs, the formality of input documentation provided by the project team, 

and whether the resulting nuclear explosive configuration would constitute an approved 

transportable configuration. The NES change evaluation will continue next week.

Conduct of Operations: Earlier this month, while installing three ballast weights on a nuclear 

explosive during assembly operations, CNS production technicians installed one of the 

components incorrectly (i.e., the ballast was inverted such that the chamfer edge was facing 

opposite of the expected configuration). CNS quality acceptance personnel discovered the 

discrepancy during a procedural hold point and nonconformed the unit. In response, CNS 

developed and executed a nuclear explosive engineering procedure to resolve the discrepancy, as 

well as briefed production technicians on the event and expectations for verbatim compliance 

with procedural steps. Furthermore, CNS process engineering plans to revise the nuclear 

explosive operating procedure to enhance directions for installation of the ballasts, including 

adding a requirement to view an additional illustration prior component placement. 

In addition, last week, while de-engraving a particular weapon component per the operating 

procedure, CNS production technicians used the incorrect housing part during milling activities. 

The use of this incorrect equipment resulted in a greater depth for the milling bit, causing 

subsequent damage to the component (i.e., the milling bit removed more material than desired). 

While the operating procedure specifies the correct identifier for the housing part, both the 

engraving and de-engraving housings are kept in the same kit and look similar. In response to 

the event, CNS initiated a nonconformance report for the component, briefed the technicians on 

the event, and reiterated the importance of verbatim compliance. Also, CNS tooling and 

machine design personnel plan to assess potential options to apply unique identifiers to the 

housing parts to prevent a similar event.