ML20332A083

Purdue University, Special Inspection Report 05000182/2020201

ML20332A083
Person / Time
Site:	Purdue University
Issue date:	12/07/2020
From:	Mohamed Shams NRC/NRR/DANU
To:	Bean R Purdue University, Indiana
Tate T
References
EA-20-144 IR 2020201
Download: ML20332A083 (19)

See also: IR 05000182/2020201

Text

December 7, 2020

EA-20-144

Dr. Robert Bean, Director

Purdue University Radiation Laboratory

School of Nuclear Engineering

400 Central Drive

West Lafayette, IN 47904-2017

SUBJECT: PURDUE UNIVERSITY REACTOR - U.S. NUCLEAR REGULATORY

COMMISSION SPECIAL INSPECTION REPORT 05000182/2020-201

Dear Dr. Bean:

This letter refers to the U.S. Nuclear Regulatory Commission (NRC) special inspection

conducted during October 27 - November 6, 2020, at the Purdue University Reactor facility.

The special inspection was conducted pursuant to event notification (EN 54958) on

October 20, 2020, later supplemented on November 3, 2020, Agencywide Documents Access

and Management System (ADAMS) Accession No. ML20311A264, describing the causes of,

and corrective actions for, operating the Purdue research reactor at power levels in excess of

the licensed maximum power level. The NRC inspectors discussed the preliminary inspection

findings with you at the conclusion of the on-site portion of the special inspection on

October 29, 2020. A final exit briefing was conducted via teleconference with you on

November 6, 2020. The enclosed report presents the results of this special inspection.

Based on the results of this special inspection, two apparent violations and one Severity

Level IV violation were identified by the NRC inspectors. The apparent violations are being

considered for escalated enforcement actions in accordance with the NRC Enforcement Policy.

The current Enforcement Policy is included on the NRCs Web site at

https://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html. The apparent violations

are related to the Purdue research reactor exceeding the maximum licensed power level

(License Condition 2.C.1) and operating the Purdue research reactor prior to completing the

applicable surveillance testing for replaced equipment (technical specification 4.2.g). The

Severity Level IV violation is related to Purdue inadequately posting a radiation area, as

required by Title 10 of the Code of Federal Regulations (10 CFR), Part 20, Standards for

Protection Against Radiation. Purdue identified the first apparent violation and notified the

NRC in EN 54958. NRC inspectors identified the second apparent violation and the Severity

Level IV violation during this special inspection. The apparent violations and the Severity Level

IV violation are discussed in the Summary of Findings, section of the enclosed report. The

circumstances surrounding these issues, the significance of the issues, and the need for lasting

and effective corrective action were discussed with members of your staff at the special

inspection exit meeting on November 6, 2020. As a result, it may not be necessary to conduct a

predecisional enforcement conference (PEC) in order to enable the NRC to make an

enforcement decision.

R. Bean -2-

In addition, since your facility has not been the subject of escalated enforcement actions within

the last 2 years and based on our understanding of your planned corrective actions, a civil

penalty may not be warranted in accordance with Section 2.3.4 of the Enforcement Policy. The

final decision will be based on you confirming on the license docket that the corrective actions

previously described to the NRC staff have been or are being taken.

Before the NRC makes its enforcement decision concerning the apparent violations, we are

providing you an opportunity to: (1) respond to the apparent violation(s) addressed in this

inspection report within 30 days of the date of this letter, or (2) request a PEC. If a PEC is held,

it will be open for public observation and the NRC will issue a press release to announce the

time and date of the conference. If you decide to participate in a PEC, please contact Mr. Travis

Tate at (301) 415-3901 within 10 days of the date of this letter. A PEC should be held within

30 days of the date of this letter.

If you choose to provide a written response for the apparent violations, it should be clearly

marked as a Response to Apparent Violations in NRC Special Inspection

Report 05000182/2020-201; EA-20-144 and should include for each apparent violation: (1) the

reason for the apparent violation or, if contested, the basis for disputing the apparent violation;

(2) the corrective steps that have been taken and the results achieved; (3) the corrective steps

that will be taken; and (4) the date when full compliance will be achieved. Your response may

reference or include previously docketed correspondence, if the correspondence adequately

addresses the required response. Additionally, your response should be sent to the NRCs

Document Control Center, with a copy mailed to Dr. Mohamed Shams, Director, Division of

Advanced Reactors and Non-Power Production and Utilization Facilities, Office of Nuclear

Reactor Regulation, 11555 Rockville Pike, Rockville, MD 20852-2738 within 30 days of the date

of this letter. If an adequate response is not received within the time specified or an extension

of time has not been granted by the NRC, the NRC will proceed with its enforcement decision or

schedule a PEC.

If you choose to request a PEC, the conference will afford you the opportunity to provide your

perspective on these matters and any other information that you believe the NRC should take

into consideration before making an enforcement decision. The decision to hold a PEC does

not mean that the NRC has determined that a violation has occurred or that enforcement action

will be taken. This conference would be conducted to obtain information to assist the NRC in

making an enforcement decision. The topics discussed during the conference may include

information to determine whether a violation occurred, information to determine the significance

of a violation, information related to the identification of a violation, and information related to

any corrective actions taken or planned.

In addition, please be advised that the number and characterization of apparent violations

described in the enclosed inspection report may change as a result of further NRC review. You

will be advised by separate correspondence of the results of our deliberations on this matter.

In accordance with 10 CFR Part 2, Agency Rules of Practice and Procedures, Section 2.390,

Public inspections, exemptions, requests for withholding, a copy of this letter, its enclosure(s),

and your response, if you choose to provide one, will be made available electronically for public

inspection in the NRC Public Document Room or from ADAMS, accessible from the NRC Web

site at http://www.nrc.gov/reading-rm/adams.html. To the extent possible, your response should

not include any personal privacy, proprietary, or safeguards information so that it can be made

available to the public without redaction.

R. Bean -3-

If you have any questions concerning this matter, please contact Mr. Travis Tate, Chief,

Non-Power Production and Utilization Facilities Oversight Branch at (301) 415-3901.

Sincerely,

/RA/

Mohamed K. Shams, Director

Division of Advanced Reactors and Non-Power

Production and Utilization Facilities

Office of Nuclear Reactor Regulation

Docket No. 50-182

License No. R-87

Enclosures:

As stated

cc: w/enclosures: See next page

Purdue University Docket No. 50-182

cc:

Mark Lundstrom, Dean of Engineering

Purdue University

School of Nuclear Engineering

400 Central Drive

West Lafayette, IN 47907

Mayor

City of West Lafayette

1200 N. Salisbury Street

West Lafayette, IN 47906

John H. Ruyack, Manager

Epidemiology Res Center/Indoor & Radiological Health

Indiana Department of Health

2525 N. Shadeland Avenue, Suite E3

Indianapolis, IN 46219

Howard W. Cundiff, P.E., Director

Consumer Protection

Indiana State Department of Health

2 North Meridian Street, Suite 5D

Indianapolis, IN 46204

Clive Townsend, Reactor Supervisor

Purdue University

School of Nuclear Engineering

400 Central Drive

West Lafayette, IN 47907

Test, Research and Training

Reactor Newsletter

Attention: Amber Johnson

Dept of Materials Science and Engineering

University of Maryland

4418 Stadium Dr.

College Park, MD 20742-2115

ML20332A083 *concurrence via e-mail NRC-002

OFFICE NRR/DANU/PM* RIII/DRP/B1* NRR/DANU/LA*

NAME POBryan JHavertape NParker

DATE 12/1/2020 12/1/2020 11/30/2020

OFFICE NRR/DANU/BC* NRR/DANU/D

NAME TTate MShams

DATE 12/2/2020 12/7/2020

NOTICE OF VIOLATION

Purdue University Docket No. 50-182

Purdue University Research Reactor License No. R-87

During a U.S. Nuclear Regulatory Commission (NRC) special inspection conducted during

October 27 - November 6, 2020, a violation of NRC requirements was identified. In accordance

with the NRC Enforcement Policy, the violation is listed below:

Title 10 of the Code of Federal Regulations (10 CFR) Section 20.1003 defines a

radiation area as an area, accessible to individuals, in which radiation levels could result

in an individual receiving a dose equivalent in excess of 0.005 rem (0.05 mSv) in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />

at 30 centimeters from the radiation source or from any surface that the radiation

penetrates.

Section 20.1902(a) of 10 CFR, Posting of radiation areas, states that, [t]he licensee

shall post each radiation area with a conspicuous sign or signs bearing the radiation

symbol and the words CAUTION, RADIATION AREA.

Contrary to the above, on several occasions between August 30, 2019, and

September 15, 2020, Purdue did not post the reactor pool top area, which was a

radiation area, with a conspicuous sign or signs bearing the radiation symbol and the

words CAUTION, RADIATION AREA. Specifically, the Purdue research reactor was

operated during this time at power levels resulting in radiation dose rates in excess of

0.005 rem per hour at 30 centimeters from the reactor pool top. The reactor pool top is

an area accessible to individuals and, despite indications that a radiation area existed at

the reactor pool top, the area was not posted as a radiation area.

This is a Severity Level IV violation (Section 6.7).

Pursuant to the provisions of 10 CFR Section 2.201, Notice of violation, the Purdue University

Reactor facility is hereby required to submit a written statement or explanation to the

U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington,

DC 20555-0001, within 30 days of the date of the letter transmitting this Notice of Violation

(Notice). This reply should be clearly marked as a Reply to a Notice of Violation, and should

include: (1) the reason for the violation, or, if contested, the basis for disputing the violation or

severity level, (2) the corrective steps that have been taken and the results achieved, (3) the

corrective steps that will be taken, and (4) the date when full compliance will be achieved. Your

response may reference or include previous docketed correspondence, if the correspondence

adequately addresses the required response. If an adequate reply is not received within the

time specified in this Notice, an Order or a Demand for Information may be issued as to why the

license should not be modified, suspended, or revoked, or why such other action as may be

proper should not be taken. Where good cause is shown, consideration will be given to

extending the response time.

If you contest this enforcement action, you should also provide a copy of your response, with

the basis for your denial, to the Director, Office of Enforcement, United States Nuclear

Regulatory Commission, Washington, DC 20555-0001.

Enclosure 1

-2-

Because your response will be made available electronically for public inspection in the NRC

Public Document Room or from the NRCs document system (Agencywide Documents Access

and Management System), accessible from the NRC Web site at http://www.nrc.gov/reading-

rm/adams.html, to the extent possible, it should not include any personal privacy, proprietary, or

safeguards information so that it can be made available to the public without redaction. If

personal privacy or proprietary information is necessary to provide an acceptable response,

then please provide a bracketed copy of your response that identifies the information that

should be protected and a redacted copy of your response that deletes such information. If you

request withholding of such material, you must specifically identify the portions of your response

that you seek to have withheld and provide in detail the bases for your claim of withholding

(e.g., explain why the disclosure of information will create an unwarranted invasion of personal

privacy or provide the information required by 10 CFR 2.390(b) to support a request for

withholding confidential commercial or financial information). If safeguards information is

necessary to provide an acceptable response, please provide the level of protection described

in 10 CFR 73.21, Protection of Safeguards Information: Performance Requirements.

In accordance with 10 CFR 19.11, Posting of notices to workers, you may be required to post

this Notice within two working days of receipt.

Dated this 7th day of December 2020

U.S. NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

Docket No: 50-182

License No: R-87

Report No: 05000182/2020-201

Licensee: Purdue University

Facility: Purdue University Research Reactor

Location: West Lafayette, IN

Dates: October 27 - November 6, 2020

Inspectors: Phil OBryan

Joshua Havertape

Approved by: Travis Tate, Chief

Nonpower Production and Utilization

Facility Oversight Branch

Division of Advanced Reactors and Non-Power

Production and Utilization Facilities

Office of Nuclear Reactor Regulation

Enclosure 2

SUMMARY OF FINDINGS

Purdue University

Research Reactor Facility

Special Inspection Report No. 05000182/2020-201

The U.S. Nuclear Regulatory Commissions (NRCs) program for overseeing the safe operation

of research and test reactors is described in Manual Chapter 2545, Research and Test Reactor

Inspection Program. In response to event notification (EN 54958) by Purdue University, a

Special Inspection Team was established in accordance with NRC Management Directive 8.3,

NRC Incident Investigation Program. The special inspection team used inspection procedure

69001, Class II Research and Test Reactors, inspection procedure 93812, Special Inspection

Team, and a special inspection charter to conduct this special inspection.

NRC-Identified and Self-Revealing Findings

1. Apparent Violation: The Purdue University reactor facility (herein referred to as Purdue)

operating license, condition 2.C.1, states that the Purdue University is authorized to

operate the facility at steady state power levels not in excess of 12 kilowatts (thermal).

Contrary to this, on several occasions between October 31, 2019, and September 15,

2020, Purdue operated in excess of 12 kilowatts (thermal).

Purdue received a license amendment (Amendment No. 14, dated April 1, 2019) that

allowed Purdue to install a digital instrumentation and control (I&C) system at their

reactor facility. This installation included replacing the nuclear instrument (NI) system

and detectors. Purdue performed the initial reactor startup after the digital I&C

modification on August 27, 2019. After the reactor startup, Purdue performed several

gold foil irradiations in order to calibrate the NI detectors. However, Purdue used an

erroneous efficiency correction factor for the instrument used to count the gold foils.

This error resulted in less conservative calculated values for actual reactor power by a

factor of approximately three. Purdue then calibrated the NI detectors based on the

incorrect calculation and NI indicated power was less than actual power by a factor of

approximately three. Since Purdue operated the reactor several times between

October 31, 2019, and September 15, 2020, at indicated power of 5 kilowatts (kW), and

at a maximum indicated power of 7.4 kW on February 14, 2020, after accounting for the

300 percent error in indicated reactor power, the actual reactor power exceeded the

maximum licensed power of 12 kW. Purdue discovered this error and license condition

violation and notified the NRC on October 20, 2020.

This is an apparent violation (AV) pending significance determination.

2. Apparent Violation: Purdues technical specification (TS) 4.2.g states that, Appropriate

surveillance testing on any technical specification required system shall be conducted

after replacement, repair, or modification before the system is considered operable and

returned to service. Contrary to this, after replacement of the NI system and detectors,

Purdue considered the NI system operable and returned it to service between

August 27, 2019, and October 9, 2020, prior to completing the appropriate surveillance

testing.

2

On August 27, 2019, Purdue restarted the reactor after an extended shutdown. During

the extended shutdown, Purdue replaced the NI system, including the NI detectors. The

plan to calibrate the NI detectors was contained in the Purdue startup plan titled Purdue

University Reactor Number One: Digital I&C Startup Plan and Checklist. This startup

plan specified eight gold foil irradiations between initial criticality and 10 kW reactor

power to complete the calibration of the NI detectors. Purdue did not complete the eight

gold foil irradiations, however, due to unexpectedly high radiation levels at the top of the

reactor pool. Nevertheless, Purdue declared the NI system operable and operated the

reactor several times between August 27, 2019, and October 9, 2020, for reasons other

than NI calibration (i.e., student and operator training, and experiments). This is an

inspector identified issue.

3. Severity Level IV Violation: A radiation area is defined in 10 CFR 20.1003 as an area,

accessible to individuals, in which radiation levels could result in an individual receiving a

dose equivalent in excess of 0.005 rem (0.05 mSv) in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at 30 centimeters from the

radiation source or from any surface that the radiation penetrates. Section 20.1902(a)

of 10 CFR, Posting of radiation areas, requires that [t]he licensee shall post each

radiation area with a conspicuous sign or signs bearing the radiation symbol and the

words CAUTION, RADIATION AREA. Contrary to this, the licensee did not post the

reactor pool top area, an accessible area with radiation dose rates in excess of 0.005

rem per hour, as a radiation area between August 30, 2019, and September 15, 2020.

After the digital I&C installation, Purdues reactor startup plan specified raising power

incrementally for NI system calibration. The startup plan also specified that radiation

dose rates were to be measured at various locations in and around the facility during

power ascension to ensure no abnormalities existed. The highest radiation levels

measured were at the reactor pool top, an area accessible to personnel. When

indicated reactor power reached approximately 1 kW, the reactor pool top radiation level

exceeded 0.005 rem per hour (5 mr/hr). Facility personnel were aware that the radiation

levels exceeded 5 mr/hr but did not recognize that this required the area to be posted as

a radiation area per 10 CFR 20.1902(a). The reactor was operated at or above 1 kW

indicated reactor power several times between August 30, 2019, and September 15,

2020. This is an inspector identified issue.

3

REPORT DETAILS

1. Introduction

a. Background

Purdue renewed their research reactor operating license in 2016. The license

renewal also increased the maximum allowed power level from 1 kW to 12 kW.

However, since Purdue was also pursuing a license amendment to upgrade the

I&C systems (License Amendment 14, dated April 1, 2019), they chose not to

operate the reactor until they installed the new I&C system. This I&C system

upgrade installed new digital I&C equipment, including a new NI system and NI

detectors.

The Purdue NI system consists of four channels. Channel 1 is the startup

channel and measures neutron flux level in counts per second (cps). This

channel does not require calibration. Channels 2, 3, and 4 read in percent

reactor power and they must be calibrated so that the measured neutron flux

level (actual reactor power) is equivalent to the reactor power indicated by the

instruments. All four NI channels, and their associated protective functions, are

required to be operable by TS 3.2 when operating the reactor. The reactor

limiting safety system setting, as defined by TS 2.2, is a reactor high power

scram setting of 12 kW. This reactor scram is initiated by the NI system.

The digital I&C system upgrade was completed in 2019. Since the NI system

instrumentation and detectors were new, Channels 2, 3, and 4 required

calibration. Purdue calibrates the NIs using gold foil irradiation. Gold foil

irradiation is performed by inserting a gold foil specimen into a tube in the vicinity

of the reactor and irradiating it for a short period of time at a constant reactor

power level. The radioactivity of the gold foil is then measured using a High

Purity Germanium (HPGe) detector, and a reactor neutron flux rate is calculated.

This calculated neutron flux rate is then used to determine a calibration factor for

each NI channel requiring calibration. Finally, the calibration factor for each NI

channel is used to adjust the NI channel and the channel is calibrated.

Purdue restarted the reactor on August 27, 2019, and used a startup plan titled

Purdue University Reactor Number One: Digital I&C Startup Plan and Checklist

as a procedure to perform various tests, including NI system calibration. This

startup plan specified using gold foil irradiation at eight different reactor power

levels from initial criticality to 10 kW reactor power.

b. Event Description

Purdue started the reactor on August 27, 2019, and, on August 29, 2019,

performed the initial gold foil calibrations of the NIs. Between August 29, 2019,

and February 14, 2020, NI detector calibrations were performed after initial

criticality, at 100 watts (W), 500 W, 1 kW, 2 kW, and 5 kW indicated reactor

power. However, while raising reactor power for the 7.5 kW indicated reactor

power level calibration on February 14, 2020, the reactor automatically

scrammed due to high radiation levels at the pool top area radiation monitor.

Calibration activities were then suspended pending resolution of the high pool top

4

radiation levels. Between initial startup and October 9, 2020, the reactor was

also operated for various other reasons such as academics, experiments, and

operator training.

On October 9, 2020, a gold foil was irradiated to validate neutron flux levels for

an experiment. The gold foil indicated that reactor power was higher than

anticipated and the cause was investigated. On October 19, 2020, Purdue staff

determined that an error occurred in calculating the HPGe detector efficiency

factor used to calculate gold foil radioactivity level for the NI calibrations

performed between August 29, 2019, and February 14, 2020. This error resulted

in NI Channels 2, 3, and 4 were calibrated so that indicated reactor power level

was less than actual power level by a factor of approximately three.

The HPGe detector efficiency determination is performed using a radioactive

check source of known radioactivity level. The radioactive check source is

counted in the HPGe detector and the measured radioactivity level is compared

to the actual source radioactivity level. An efficiency factor is then calculated

based on the difference between the measured and the actual radioactivity

levels. Gold foils must be counted in the same position and distance from the

HPGe detector for the efficiency factor to be valid for NI calibration calculations.

On October 19, 2020, the HPGe detector efficiency calculations from August

2019 and October 2020 were compared. Purdue noted that the calculated HPGe

detector efficiency factors differed by a factor of approximately three, and it was

determined that the gold foils used for NI calibration starting in August 2019 were

counted at a different HPGe shelf location (i.e. different distance) than the

radioactive check source used for the HPGe detector efficiency calculation.

The NI calibrations performed between August 29, 2019, and February 14, 2020,

were performed using the incorrect HPGe efficiency factor. Since the reactor

was operated several times between October 31, 2019, and September 15,

2020, above 4 kW indicated power, the actual reactor power exceeded 12 kW

during these operations. The highest actual reactor power reached was on

February 14, 2020, and was between 18 kW (Channel 3 indication) and 22.2 kW

(Channel 4 indication).

5

Sequence of Events

The inspectors interviewed licensee personnel, reviewed records, and observed

demonstrations conducted by the licensee to develop the sequence of events leading up

to and following the events described above.

4/1/2019 Digital I&C License Amendment approved.

Early 2019 (exact date unknown) the digital I&C system installation was completed.

08/27/2019 The reactor was started up for the first time after the extended

shutdown using an auxiliary nuclear instrument and NI Channel 1.

08/29/2019 The first three gold foil irradiations were performed at approximately

1 W, 10 W, and 100 W calculated reactor power. NI Channels 2 and 3

calibrations were adjusted using an incorrect HPGe detector efficiency

factor. The pool top radiation level for the calibrations was recorded as

less than 1 milliroentgen per hour (<1 mr/hr).

08/30/2019 The fourth gold foil irradiation was complete at a calculated reactor

power of approximately 500 W. NI Channels 2, 3, and 4 calibrations

were adjusted. Radiation surveys at the reactor pool top determined

that the radiation level was 3 mr/hr.

Later that day, the reactor was started again and indicated reactor

power was raised to approximately 1 kW. Pool top radiation surveys

were not recorded.

8/31/2019 - The reactor was not operated.

9/16/2019

9/20/2019 The fifth gold foil irradiation was performed at a calculated power of

approximately 1 kW. NI Channels 2, 3, and 4 calibrations were

adjusted. At 954 W, the pool top radiation level was measured to be

5 mr/hr.

Later that day, the reactor was started, and calculated reactor power

was raised to 2 kW for the first time. Pool top radiation levels were not

recorded.

10/09/2019 The sixth gold foil irradiation was complete at a calculated reactor

power of approximately 2 kW. No NI channel calibration adjustments

were made based on this irradiation. The pool top radiation level was

recorded as 13 mr/hr.

10/10/2019 Channel 2 calibration adjusted due to detector relocation. The reactor

was started and operated at an indicated reactor power of 600 W, then

shutdown.

Pool area radiation monitor setpoints were adjusted to an alert setpoint

of 30 mr/hr and scram setpoint of 50 mr/hr.

6

10/15/2019 - The reactor was operated three times. No calibration adjustments or

10/29/2019 gold foil irradiations were performed.

10/30/2019 The seventh gold foil was irradiated at a calculated reactor power of

approximately 2 kW. No radiation surveys were documented.

10/31/2019 Channels 2, 3, and 4 calibration adjustments were made based on the

irradiation performed on 10/30/2019.

The reactor was started for the next gold foil irradiation at 5 kW, but the

reactor scrammed before reaching 5 kW due to a high radiation scram

signal from the pool top radiation monitor. Purdue determined that the

scram signal was erroneously generated at 20 mr/hr. This was the first

time that the reactor was operated above 4 kW calculated reactor

power, which correlated to an actual reactor power of greater than

12 kW - Purdues maximum licensed power level.

11/1/2019 - The reactor was operated regularly for student and operator training.

12/11/2019

12/12/2019 The eighth gold foil was irradiated at a calculated reactor power of

approximately 5 kW. No radiation survey documented.

12/13/2019 Channels 2, 3, and 4 calibration adjustments were made based on the

gold foil irradiation performed on 12/12/2019. The reactor was started

and operated at 5 kW calculated reactor power.

12/14/2019 - The reactor was not operated.

1/28/2020

1/29/2020 - The reactor was operated several times for student and operator

2/12/2020 training.

2/14/2020 The reactor was started, and an attempt was made to raise reactor

power to 7.5 kW. However, the reactor experienced a high pool

radiation level scram prior to reaching 7.5 kW. Recorders indicated that

the pool top radiation level briefly reached the scram setpoint of

50 mr/hr. The highest indicated reactor power was 6 kW on NI

Channel 3 and 7.4 kW on NI Channel 4. The highest actual reactor

power reached was between 18 kW (Channel 3 indication) and 22.2 kW

(Channel 4 indication).

2/14/2020 - The reactor was operated four times for student and operator training.

3/12/2020

3/13/2020 - The reactor was not operated. A camera inspection of the reactor on

9/8/2020 8/11/2020 revealed no abnormalities.

09/09/2020 - The reactor was operated three times for student and operator training.

9/18/2020

7

10/9/2020 The ninth gold foil was irradiated at approximately 250 W indicated

reactor power to verify neutron flux levels for an experiment.

10/19/2020 Purdue determined that the HPGe detector efficiency factor

determination used for NI calibrations was incorrect by a factor of

approximately three in the nonconservative direction (i.e. indicated

power was lower than actual power by a factor of three).

2. Adequacy of Facility Procedures for Nuclear Instrument Calibration

The Purdue procedure for NI calibration is Standard Operating Procedure 4 (SOP-4),

Power Calibration by Gold Foil. While reviewing this event, Purdue found that SOP-4

was inadequate because it did not require an independent operator to verify key

parameters and calculations. SOP-4 also relied on skill of the craft, and did not include

detailed procedural steps for portions of the calibration process.

For example, one person determined HPGe detector efficiency and performed the

detector efficiency factor calculation. This person relied only on his knowledge of HPGe

detector operation and did not use a procedure. The calculated efficiency factor was

then recorded in a notebook. Although it was the habit of Purdue operators to have the

calculations second checked, this was not a requirement. The lack of a required

independent verification introduced opportunities for errors and inconsistencies in the

key parameters and calculations to not be captured. NRC inspectors agreed with

Purdues assessment of this procedure.

The Purdue start up plan, Purdue University Reactor Number One: Digital I&C Startup

Plan and Checklist, specified how the reactor would be started and tested after the

digital I&C modifications, including methodology for performing the gold foil NI

calibrations. NRC inspectors found that this procedure contained weaknesses including

1) lack of guidance on TS operability requirements after NI system replacement, 2) lack

of guidance for determining radiation levels inside the reactor bay when raising reactor

power beyond previous maximum power levels and ensuring all areas met posting

requirements of 10 CFR 20.1902, Posting Requirements, 3) lack of guidance for

required actions if procedural steps could not be completed, if other actions were taken

that could affect NI calibration, or if the procedure was suspended, and 4) lack of

guidance for the use of diverse reactor parameters, such as radiation levels, control rod

bank height, and gold foil activity levels from historical NI calibrations to verify indications

of reactor power.

3. Licensee Response to the Event

Maximum reactor power level was incrementally raised over several months after the

Purdue reactor restart. As the maximum power was raised, Purdue operators noticed

pool top radiation levels were higher than expected. In fact, Purdue realized that they

would not be able to complete high power NI calibrations without causing pool top

radiation monitor alarms and protective action (high radiation scram). On October 10,

2019, Purdue raised the pool top radiation alarm setpoint to 30 mr/hr and the pool top

high radiation scram setpoint to 50 mr/hr - the highest radiation scram setpoint allowed

by TS. Purdue could not definitively explain the high radiation levels. Potential reasons

discussed by the Purdue staff included having a new pool top radiation monitor which

8

was in a different location than the old radiation monitor, and irradiation ports streaming

radiation through the pool water.

On February 14, 2020, the reactor scrammed due to a high pool top radiation level while

attempting to raise reactor power to 7.5 kW indicated reactor power. Purdue responded

to the February 14, 2020, pool top high radiation reactor scram by suspending reactor

operations above 5 kW indicated reactor power, which they believed was the highest

reactor power for which a successful NI calibration was performed. They also relocated

irradiation ports away from the reactor to reduce streaming radiation. Purdue reported

that relocating irradiation ports reduced the pool top radiation level but did not record the

magnitude of the reduction. Reactor operations continued until October 9, 2020, when a

gold foil was irradiated and indicated that actual reactor power was significantly higher

than indicated reactor power.

NRC inspectors found that there were opportunities for Purdue to more comprehensively

investigate the cause of the high pool top radiation levels and failed to do so. NRC

inspectors determined that formal investigative techniques, such as a fault tree analysis,

were not used. NRC inspectors noted that Purdue was disadvantaged in their

investigation by not having comparable historical NI data because all components of the

NI system were newly installed.

4. Root Cause Determination and Contributing Causes

Purdue determined that the root cause of the event was an error in the calculation of the

HPGe efficiency factor. Purdue also identified the following contributing causes:

1) The HPGe detector efficiency factor determination was not independently verified,

2) The HPGe detector efficiency factor was determined without the use of a procedure,

and

3) The previous NI system calibration settings were not relevant to the new NI system

calibration settings, and therefore, no historical information was available to

determine if settings were reasonable.

Purdue also determined that the cause of the failure to post the reactor bay as a

Radiation Area was caused by a lack of procedures to determine radiation levels in the

reactor bay after power uprate.

NRC inspectors agree with the causes listed above and identified the following additional

contributing causes of the event:

1) Skill of the craft in lieu of procedural use is common at Purdue,

2) Radiation surveys were informally performed in the reactor bay and operators failed

to record radiations levels on several occasions during power ascension,

3) Purdue reactor management considered the NI system to be operable before the NI

system was calibrated at reactor power levels above 5 kW, and

4) The Reactor Safety Committee did not formally review each startup plan delay and

procedural deviation.

9

5. Corrective Actions

Purdue implemented, or plans to implement, the following corrective actions:

1) SOP-4 was revised to require two independent determinations of the HPGe detector

efficiency factor, two independent measurements of gold foil radioactivity level, and

two independent calculations of reactor power for NI calibrations,

2) The startup plan was revised to include:

a. requirements for measuring radiation levels during power ascension and

verifying postings in the reactor bay and in adjacent areas of the facility,

b. steps to conservatively increase the initial NI calibration factors by a factor of

10 and reperforming all gold foil calibrations,

c. directions to not allow reactor operations for anything other than NI

calibration,

d. directions for using NI channel data from previous reactor operations as a

cross check of reactor power, and

e. a requirement that members of the Reactor Safety Committee review and

approve deviations from the startup plan.

3) Other reactor procedures will be reviewed to identify when the procedure relies

excessively on skill of the craft assumptions,

4) Radiation survey requirements will be specified in facility procedures and reactor

operators in training will be qualified as radiation workers.

5) Purdue TSs will be amended prior to startup to clarify allowances for reactor

operation in order to calibrate repaired, replaced, or modified NI channels.

NRC inspectors found that these corrective actions are adequate to prevent recurrence

of the event.

6. Related Actions that Contributed to the Event

As discussed in Section 5 of this report, there were several factors that contributed to the

event. Additionally, NRC inspectors noted that Purdues actions were often not

consistent with the NRCs policy statement on nuclear safety culture. The NRC defines

nuclear safety culture as: the core values and behaviors resulting from a collective

commitment by leaders and individuals to emphasize safety over competing goals to

ensure protection of people and the environment.

With regards to identifying NI calibration errors, NRC inspectors found that

Purdue demonstrated weaknesses with the following nuclear safety traits:

1) Problem Identification and Resolution, defined as Issues potentially

impacting safety are promptly identified, fully evaluated, and promptly

addressed and corrected commensurate with their significance, and

2) Questioning Attitude, defined as Individuals avoid complacency and

continually challenge existing conditions and activities in order to identify

discrepancies that might result in error or inappropriate action.

With regards to excessive skill of the craft use and procedural deviations,

NRC inspectors found that Purdue demonstrated weaknesses in the nuclear

safety trait of Work Processes, defined as The process of planning and

controlling work activities is implemented so that safety is maintained.

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7. Consequences of the Event

The NRC inspectors determined that there were no actual nuclear safety consequences

as a result of this event. The NRC inspectors found the Purdue reactor safety analysis

demonstrates that the reactor fuel will not exceed its temperature safety limit of 530

degrees centigrade at a reactor power of 98.6 kW. Since the highest actual reactor

power reached during the event was approximately 22.2 kW, no fuel damage is

expected. The NRC inspectors found that a fuel inspection performed by Purdue in

August 2020, reactor pool water chemistry analyses, and facility radiation surveys

confirm that no fuel damage occurred. NRC inspectors determined that there are no

other reactor components susceptible to damage at a reactor power level of 22.2 kW.

Since the NI system would have initiated a reactor scram during an over-power scenario

at 36 kW actual reactor power (three times an indicated reactor power setpoint of

12 kW), the reactor fuel would also be undamaged during this type of accident.

The NRC inspectors determined that radiation levels in the reactor bay during the event

contributed to slightly higher dose rates for personnel in the reactor bay during reactor

plant operations, but these doses were within regulatory limits established in 10 CFR

Part 20, Standards for Protection Against Radiation, as measured by personnel

dosimetry. The highest dose rate at the reactor console occurred when the reactor

operated at 22.2 kW actual reactor power on February 14, 2020. The area radiation

monitor in the vicinity of the console recorded the dose rate as 0.13 mr/hr above

background level during this time period. This dose rate, and the dose rates at lower

reactor power levels, would contribute only a small amount to operators doses for the

relatively short time that the operators were at the console (typically 1 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />).

The NRC inspectors determined that area radiation monitors located on the walls of the

reactor bay read <0.1 mr/hr throughout the event. Therefore, dose rates in uncontrolled

areas did not exceed the regulatory dose rate limit of 2 mr/hr. NRC inspectors found

dosimeters located in adjacent spaces also showed that the maximum dose in any

uncontrolled area, assuming constant occupancy, did not exceed the regulatory limit of

100 millirem. Actual occupancy in adjacent, uncontrolled spaces was much less than

this. Therefore, inspectors found that radiation dose consequences of this event were

insignificant.

8. Exit Interview

The NRC inspectors conducted an inspection debrief with Purdue reactor management

at the conclusion of the onsite portion of the special inspection on October 29, 2020.

NRC inspectors discussed the inspection results in an inspection exit meeting at the

conclusion of the special inspection with Dr. Bean, Facility Director and members of his

staff on November 6, 2020.

11

PARTIAL LIST OF PERSONS CONTACTED

Licensee Personnel

R. Bean Facility Director

C. Townsend Reactor Supervisor

D. Storz Reactor Instrumentation Specialist

Other Personnel

M. Tang Interim Radiation Safety Officer

INSPECTION PROCEDURES USED

IP 69001 Class 2 Research and Test Reactors

IP 93812 Special Inspection

ITEMS OPENED, CLOSED, AND DISCUSSED

OPENED

50-182/2020-201-01 AV Exceeding Maximum Licensed Power Level

(License Condition 2.C.1)

50-182/2020-201-02 AV Operating with Inoperable Nuclear Instrumentation

(TS 4.2.g).

50-182/2020-201-03 VIO Failure to Post a Radiation Area

(10 CFR 20.1902(a))

Licensee Documents Reviewed

• Purdue University Reactor Number One: Digital I&C Startup Plan and Checklist,

Revision 0

• Purdue University Reactor Number One: Operating Principles and Core Characteristics

Manual, Revision 0

• Purdue University Reactor Number One, Standard Operating Procedure 4, SOP-4,

Power Calibration by Gold Foil, Revision 1

• Reactor Console Logbook from August 22, 2019, to October 23, 2020

• Report on Reactor Operations for January 1, 2019, to December 31, 2019

• Purdue University Reactor Water Analysis Report, dated October 12, 2020

Attachment