DEFENSE NUCLEAR FACILITIES SAFETY BOARD

January 19, 2024

TO: Katherine R. Herrera, Acting Technical Director

FROM: B. Caleca, P. Fox, N. Huntington, and P. Meyer, Resident Inspectors

SUBJECT: Hanford Activity Report for the Week Ending January 19, 2024

Hanford Site: Site operations were impaired by abnormally cold temperatures, ice, and snow

throughout the week. Snow and freezing rain resulted in early dismissal of dayshift personnel

(except essential personnel) and cancellation of backshift work on two days and a full day 

closure on Friday. Additionally, low temperatures caused difficult work conditions and damaged 

systems at several facilities. At the 222-S Laboratory, a heat pump for the maintenance annex

was out of service leading to cold temperatures inside the building, freezing some fire 

suppression pipes and damaging several sprinkler heads. The heat pump was restored after the 

frozen pipes were discovered and, because of the damage, HLMI isolated a water riser that 

supplies fire suppression sprinklers to the area. Work activities are restricted until the system is 

repaired. HMIS Fire Systems Maintenance is putting together a work package to determine the 

extent of damage to the sprinkler system. The low temperatures, along with insufficient freeze 

protection measures, also resulted in a damaged fire main riser at the Waste Treatment Plant 

(WTP) Low Activity Waste Facility. Freezing also caused blocked pipes in other systems 

around the WTP site. WTCC is working to determine the full extent of the conditions. 

242-A Evaporator: After shutting down part of the facility’s ventilation system to perform 

routine maintenance, the system was unable to achieve an adequate flow rate after restart. This

condition engaged an interlock that prevented the heating system to the building from operating 

for several hours. This is the same interlock that shut off heating to the facility last year leading 

to extensive freeze damage to multiple systems and triggered a need for months of repair work,

as well as changes to operating procedures and the facility’s safety basis (see 1/6/2023 and 

12/22/2023 reports). Facility operators identified the loss of heat during the performance of 

other duties and swiftly performed actions to address the problem. While temperatures did not 

fall below freezing in the facility, temperatures did fall below low temperature alarm levels in 

some areas and did not fully recover for several days. The startup procedure for the fans 

required verification of adequate flow rates by the stationary operating engineer (SOE) 

responsible for the ventilation system, and the ventilation control system can send an alarm to the 

facility control room once temperatures drop below 55 degrees Fahrenheit. However, the SOE 

did not notify the control room that the flow rate was unsatisfactory, and a pre-existing alarm 

condition, which has been known to facility personnel, prevents any new alarms from 

transmitting to the control room. As a result, the expected signals to prompt operator actions

were not effective. Facility management has instituted temporary rounds that require verification 

of ventilation system operability by an SOE and periodic performance of manual temperature 

readings by facility operators throughout the facility until the alarm malfunction can be 

corrected.

Waste Treatment Plant: Tie breakers that allow the standby diesel generator (SDG) to supply 

power to plant systems were left racked out after workers completed maintenance on the SDG in 

mid-October. The abnormal condition, which prevents the SDG from performing its primary 

function, was not discovered until last week, indicating a potential shortcoming in configuration 
control processes for facility systems.