Information Notice 2023-03, Recent Human Performance Issues at Non-Power Production and Utilization Facilities

Recent Human Performance Issues at Non-Power Production and Utilization Facilities

ML23059A539
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Issue date:	06/13/2023
From:	Arellano J, Duane Hardesty NRC/NRR/DANU
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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, DC 20555-0001 June 13, 2023 NRC INFORMATION NOTICE 2023-03: RECENT HUMAN PERFORMANCE ISSUES AT

NONPOWER PRODUCTION AND UTILIZATION

FACILITIES

ADDRESSEES

All holders of and applicants for an operating license or construction permit for a non-power

production or utilization facility (NPUF) issued under Title 10 of the Code of Federal Regulations

(10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, including those

that have permanently ceased operations and certified that fuel has been permanently removed

from the reactor vessel.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform

addressees of recent events at NPUFs that were attributed, at least in part, to inadequate

procedures, human performance, or safety culture issues. The NRC expects recipients to

review the information for applicability to their facilities and to consider actions, as appropriate, to avoid similar problems. Suggestions contained in this IN are not NRC requirements;

therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

The following recent events are identified by the NRC staff as human performance or safety

culture issues that have occurred at NPUFs. These events are selected and summarized from

NRC inspection reports and licensee event notices.

Reactor Power Level Greater than Nuclear Instrumentation Indications

Between August 29, 2019, and February 14, 2020, the Purdue University Research Reactor

(PUR-1) personnel performed calibrations of nuclear instruments following replacement of the

nuclear instrumentation (NI) system and detectors. The process involves bringing the reactor

critical and performing detector calibrations at different power levels to irradiate gold foil. The

gold foil in turn is placed in a high-purity germanium (HPGe) detector to obtain a reactor neutron

flux rate for that location of irradiation. Using a calibration factor, relating the flux at the location

of the gold foil irradiation to the whole core fission rate, the power level of the run can be

determined. This calculated power level is then used to determine a calibration factor for each

NI channel requiring calibration. The PUR-1 procedures required eight gold foil irradiations;

however, the licensee did not complete the irradiations because of unexpectedly high radiation

levels at the top of the reactor pool. The PUR-1 personnel declared the NI system operable and

operated the reactor several times for student and operator training and experiments.

ML23059A539 On October 31, 2019, while attempting to perform gold foil irradiation at 5 kilowatts (kW), the

reactor scrammed before reaching 5 kW because of a high-radiation scram signal from the pool

top radiation monitor. The PUR-1 personnel declared that the scram signal was erroneously

generated and continued to operate the reactor regularly for student and operator training. On

February 14, 2020, the reactor automatically scrammed again because of high radiation levels

at the pool top area radiation monitor. On October 19, 2020, a gold foil was irradiated to validate

the neutron flux levels for an experiment. The gold foil measurements of the neutron flux rate

indicated reactor power was higher than anticipated. PUR-1 personnel determined the HPGe

detector efficiency factor, which is used to determine gold foil radioactivity for the NI calibrations

had been incorrectly calculated. The error resulted in reactor power levels being approximately

3 times that of the power level indicated on the NI channels. It was determined that PUR-1 operated at steady-state levels above the maximum licensed power level on several occasions.

The PUR-1 personnel took the following corrective actions related to this event:

• revised the NI calibration procedure to require independent measurement of the gold foil

activity and reactor power data by a second individual.

• revised standard operating procedures to require that members of the Reactor Safety

Committee are required to review and approve startup plan deviations.

• revised procedures to reduce the staffs reliance on skill of the craft when performing

reactor activities and operations.

• implemented additional procedures for radiation area mapping and protocols, including

posting signage at the entrance to the PUR-1 facility bearing the radiation symbol and

the words, "CAUTION, RADIATION AREA."

• amended the technical specifications, prior to resuming reactor operations, to clarify

allowances for reactor operation to calibrate repaired, replaced, or modified NI channels.

Safety Limit Violation

On February 3, 2021, following a refueling outage, the National Institute of Standards and

Technology Center for Neutron Research (NCNR) experienced an emergency alert event that

resulted in exceeding the licensed technical specification safety limit for reactor fuel

temperature. The event was initially discovered when the reactor automatically shut down in

response to indications of high radiation from the confinement exhaust stack. Once the reactor

was placed in a safe condition, all NCNR personnel evacuated the control room and reactor

confinement. For the event, offsite radiation dose measurements were near background levels.

Radiation dose to the workers from the event was well below regulatory limits. Subsequently, the licensee determined that operators had improperly verified the placement of fuel elements

when performing latch verification rotation checks. A fuel element became unlatched during

reactor startup resulting in damage to a fuel element, which caused the exhaust stack radiation

alarm. The licensees root cause analysis determined that the incident was due to several

factors, including understaffing and lack of resources, an environment not conducive to staff

raising concerns, and management not resolving staff concerns, and other factors related to

procedures. The NRC staff determined that the procedures were not followed, were poorly

understood, lacked details and precautions, lacked context and significance, and did not

reference applicable technical specifications. Other contributing factors were determined to be

inadequate leadership, ineffective corrective action programs, safety culture weakness, and

failure to implement safety committee recommendations. The NCNR personnel took the following corrective actions related to this event:

• implemented a program to incentivize staff to identify, raise, and address safety

concerns.

• established the Safety Evaluation Committee subcommittee to track and oversee

corrective actions.

• modified conduct of operations to strengthen the oversight role of supervisors and to

improve training requirements for management and operators.

• modified procedures for latch checks.

• enhanced training for operators performing fuel handling, including core loading, shuffle, rotational latch checks, and visual latch checks.

• revised the reactor startup procedure to provide detailed guidance on evaluation of

abnormal conditions.

Failure to Manage Changes in Reactivity

On November 23, 2022, the University of New Mexico reactor (AGN-201M) experienced an

unintentional high-power scram while conducting a sample irradiation. The reactor is licensed to

a maximum steady-state power level of 5 watts and has an automatic high-power scram at

6 watts. An iodized table salt sample was inserted into the centerline of the reactor core for

irradiation for approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> with the reactor stabilized at 4 watts. The sample, which

provides negative reactivity, was removed adding positive reactivity to the core. During this

removal process, the reactor power increased to 6 watts, initiating an automatic high-power

scram.

The licensee identified that inadequate communication between sample handlers and reactor

operators resulted in a failure to ensure that reactivity differences between samples and control

rods were accounted for during operations. Appropriate communication prior to the sample

being removed from the core allows the reactor operator to adjust control rods for anticipated

reactivity changes.

The University of New Mexico personnel took the following corrective actions related to this

event:

• developed and conducted specific training to cultivate awareness about the

circumstances of the unscheduled high-power scram.

• implemented specific training on proper communications and coordination between the

operator and assistant during evolutions.

• clarified the training and operations manual to emphasize that unscheduled high-power

scrams are reportable occurrences and must be promptly reported to the NRC.

Fuel Elements not Inspected

On December 4, 2019, Kansas State University personnel identified four fuel elements that

were not visually inspected for corrosion and mechanical damage as required by technical

specifications. The four fuel elements outside of the required surveillance frequency were not marked for inspection. The licensees review of inspection records found different inspection

due dates for the same fuel elements. Personnel error in maintaining the fuel element inspection

tracking spreadsheet resulted in a mismatch between the fuel element serial numbers and the

last inspection date.

Kansas State University personnel took the following corrective actions related to this

occurrence:

• suspended reactor operations until the event could be reviewed by the Reactor Safety

Committee.

• inspected the four elements identified and performed a complete review of the fuel

inspection records.

• reviewed the event with all reactor staff.

• revised the fuel element inspection tracking document to accurately reflect current

conditions.

Release Values Not Calculated Correctly

During a routine NRC inspection at the Missouri University of Science and Technology Reactor

(MSTR), the NRC inspector discovered that a valid experimental verification of calculated

argon-41 release values had not been performed since 2007. Specifically, argon-41 release

values were performed incorrectly because of errors in the experimental verification

methodology, thus invalidating the verifications. The MSTR technical specifications require the

licensee to perform an experimental verification of calculated airborne effluent release values

every 5 years and when a change in licensed power occurs. The methodology for the

experimental verification of airborne releases from the MSTR facility from 2008 to 2019 did not

establish a ventilation configuration that was consistent with assumptions in the airborne

radioactivity calculations used to determine the magnitude of airborne radioactive effluents. This

error resulted in the licensee underestimating the amount of airborne radioactivity released. The

MSTR personnel identified the underlying cause of the errors as inadequate quality assurance, knowledge atrophy, and use of methods and procedures handed down from previous health

physics personnel, that had not been questioned or verified. After correcting the data, MSTR

personnel reported that the airborne radioactive effluents were within the limits established in

10 CFR Part 20, Standards for Protection against Radiation.

The MSTR personnel took the following corrective actions related to this event:

• revised the MSTR technical specifications to require argon-41 experimental verification

measurements to be taken every 3 years instead of every 5 years to reduce knowledge

atrophy and to ensure competency in performing the verification.

• revised the procedures for measurement of argon-41 concentration in the reactor

building to improve experimental verification setups.

• implemented a training/qualification program for personnel performing health physics

activities and surveys. This program identifies and addresses specific knowledge and

training requirements (including refresher training) for each survey type.

• implemented actions for management to address staffing and enrollment in the operator

training program to reduce reliance on a single operator to perform all surveillances. Operation with Unauthorized Fuel Elements

On October 18, 2022, the operations staff at the University of Texas at Austin Nuclear

Engineering Teaching Laboratory (NETL) discovered reactor operations were conducted with

two unauthorized aluminum-clad standard TRIGA fuel elements loaded in its core. Only

stainless-steel clad TRIGA fuel elements are authorized by the technical specifications. On

January 4, 2022, following a routine fuel inspection, 10 fuel elements, including the two

aluminum fuel elements, were installed in the reactor core to increase excess reactivity. The

aluminum-clad elements were chosen for insertion because they were listed in the tracking file

as having low burnup. The tracking file also lists the notation Al SFE, to specify that the

elements were aluminum clad. The operations staff missed this notation when selecting these

elements to insert into the reactor core. The NETL procedures did not include instructions or

require an independent review to verify the fuel cladding before moving the element into the

core. The reactor operated with the aluminum-clad elements in an unanalyzed condition from

January 6, 2022, to October 17, 2022. The licensees visual inspection determined that there

was no damage to the elements. The licensees technical analysis of the operating conditions

experienced by the unauthorized fuel elements found that the cladding temperature remained

below the safe temperature limit. The licensee identified the root cause for the event as the lack

of administrative or engineered barriers to segregate or control operator access to disqualified

fuel.

The NETL personnel took the following corrective actions related to this occurrence:

• suspended reactor operations.

• removed the aluminum clad fuel elements from the core and visually inspected the

affected elements for damage.

• revised the surveillance procedure for fuel element inspection and performed the revised

surveillance for the core configuration before startup.

• revised the tracking file to include the date of last fuel inspection and a qualified or

disqualified flag to indicate fuel elements allowed to be used in the core.

Failure to Maintain Minimum Staffing

On March 19, 2018, General Electric-Hitachi (GEH) reported that, while operating at

100 percent power, the licensed operator left the Nuclear Test Reactor (NTR) facility control

room without proper relief.

On March 4, 2019, GEH discovered the NTR was not properly secured since the licensed

operator exited and locked the control room but failed to remove the console key from the

console lock switch and store it in the designated safe. Therefore, the NTR was in violation of

minimum staffing when the reactor is not secured as required by the facility technical

specifications.

GEH took the following corrective actions related to these occurrences:

• attached the console key to a large, highly visible key chain, and implemented a flagging

system to increase the likelihood of operators seeing the flag when the console key is

not in proper custody.

• trained the NTR staff on the importance of securing the reactor before exiting the control

room.

DISCUSSION

The human performance events discussed above, for the most part, involved failure of licensees

to provide adequate procedures, failure of operators to properly follow those procedures, or

both. In several instances, it appeared that risk was either underestimated or not considered.

Overall, the events can be attributed to weaknesses in safety culture, such as an operators loss

of focus on safety, (e.g., taking actions when the consequences of those actions are uncertain

or acting outside the scope of the relevant procedure(s)).

These examples represent a sample of recent events in which human performance played a

key role, and each highlights the notable challenges that human performance weaknesses may

present to facility operation. Operating the facility and reactor in accordance with procedures is

the primary responsibility of all operating staff. Operating experience shows that errors often

occur before, during, and immediately following evolutions that are less familiar to the

operations staff because they are performed infrequently. Some events show that individuals

became complacent and did not recognize and plan for the possibility of mistakes, latent issues, and inherent risk. The events related to surveillances, such as calibrations and inspections, could have reasonably been prevented by fostering a positive safety culture.

To prevent events related to human performance issues, managers and leaders should

reinforce that all individuals should take personal responsibility for safety. Licensees should

maintain a positive safety culture at their facilities, including demonstrating a commitment to

safety in all decisions and behaviors. This includes reinforcing traits among personnel to

identify, fully evaluate, and address issues potentially impacting safety to ensure they are

promptly corrected. The facility personnel should avoid complacency and question existing

conditions and activities to identify discrepancies that might result in errors or inappropriate

actions. Processes and procedures and the work activities they support should be planned, controlled, and implemented so that safety is maintained. Many of the issues identified in this

Information Notice were self-identified and corrected by the licensees. The NRC staff continues

to encourage all personnel to practice effective safety communication and for licensees to self- identify and correct problems. Refer to https://www.nrc.gov/about-nrc/safety-culture.html for

more information on safety culture.

The root causes are not reactor-specific activities, and the operational experience can apply to

any NPUF licensee.

CONTACT

This IN requires no specific action or written response. If you have any questions about the

information in this notice, please notify the technical contacts listed below.

/RA/

Mohamed K. Shams, Director

Division of Advanced Reactors and

Non-power Production and Utilization

Facilities

Office of Nuclear Reactor Regulation

/RA/

Russel N. Felts, Director

Division of Reactor Oversight

Office of Nuclear Reactor Regulation

Technical Contacts: Duane Hardesty, Senior Project Manager, NRR

(301) 415-3724 E-mail: Duane.Hardesty@nrc.gov

Juan Arellano, Reactor Inspector, NRR

(301) 415-0477 E-mail: Juan.Arellano@nrc.gov

Contributors: Linh Tran, Senior Project Manager, NRR

Cindy Montgomery, Project Manager, NRR

Paulette Torres, Project Manager, NRR

Andrew Waugh, Reactor Inspector, NRR

Note: NRC generic communications may be found on the NRC public website, https://www.nrc.gov, under NRC Library.

ML23059A539 EPID No. L-2023-GEN-0003 OFFICE NRR/DANU/UNPL NRR/DANU/UNPO QTE NRR/DANU/UNPO:BC NRR/DANU/UNPO:BC

NAME DHardesty JArellano JDougherty TTate JBorromeo

DATE 4/6/2023 3/8/2023 3/24/2023 4/12/2023 4/12/2023 OFFICE NRR/DRO/IOEB NRR/DRO/IOEB:LA NRR/DRO/IOEB:BC NRR/DRO/IOEB/D NRR/DANU/D

NAME PClark IBetts LRegner RFelts MShams

DATE 4/28/2023 6/1/2023 6/1/2023 6/5/2023 6/13/2023