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Letter to Dr. Theresa A. Maldonado from Christopher I. Grimes NRC Special Inspection Report No. 50-128/2006-203 and Notice of Violation
	ML061090188
Person / Time
Site:	05000128
Issue date:	05/11/2006
From:	Charemagne Grimes; NRC/NRR/ADRA/DPR
To:	Maldanado T; Texas A&M Univ
	Mendonca M, NRC/NRR/DPR/PRT, 415-1128
References
	EA-06-113 IR-06-203
	Download: ML061090188 (35)
	v • d • e

May 11, 2006

EA-06-113

Dr. Theresa A. Maldonado, Deputy Director

Texas Engineering Experiment Station

Texas A&M University

1095 Nuclear Science Road

College Station, TX 77843-3575

SUBJECT: NRC SPECIAL INSPECTION REPORT NO. 50-128/2006-203 AND NOTICE OF

VIOLATION

Dear Dr. Maldonado:

On March 29, 2006, the Nuclear Regulatory Commission (NRC) completed a Special Inspection

at your Texas Engineering Experiment Station, Nuclear Science Center Research Reactor

Facility. The special inspection included an examination of activities conducted under your

license as they relate to safety and compliance with the Commissions rules and regulations

and with the conditions of your license. Within these areas, the inspection included selected

examination of procedures and representative records, observations of activities, and interviews

with personnel. The enclosed report documents the inspection findings, which were discussed

with you, Dr. W. D. Reece, the Facility Director, and Dr. Latha Vasudevan, the facility Radiation

Safety Officer, on March 29, 2006.

The event that led to the conduct of the Special Inspection can be summarized as follows:

During work involving radioactive material, licensee employees of the Texas Engineering

Experiment Station, Nuclear Science Center (NSC) are required to wear an Optically Stimulated

Luminescent dosimeter for whole body monitoring and a finger ring containing a

thermoluminescent dosimeter chip for extremity monitoring. At the end of January 2006, the

NSC Radiation Safety Officer (RSO) gathered all the dosimeters used during the month by

facility personnel and sent them to the dosimetry vendor for processing. The RSO did not

receive the dosimetry results report until February 24, 2006. The report indicated that a worker,

who had been conducting neutron activation analysis (NAA) using the pneumatic transfer

system during January, had received a potential extremity overexposure. The NSC Facility

Director and RSO immediately noted the results, restricted the worker from further work with

radioactive material that would contribute to an extremity dose, and began a review of the

situation. After consideration of various factors, the Director and RSO determined that the

extremity dose was an apparent anomalous result. The person involved was placed on

restricted duty and allowed to continue work, although all the sample processing work for

February had been completed at that point.

At the end of February, personnel dosimeters were again gathered and sent to the vendor for

processing. Those dosimetry results, which were received on March 15, 2006, indicated that

the worker conducting NAA using the pneumatic system had received a much higher than

normal extremity dose during February. The licensee notified the NRC of the event on

March 15, 2006. Subsequently, by written report dated April 14, 2006, you concluded that there

was no overexposure of that individual or any individual at your facility. Additionally in your

2

written report you indicated that you have taken or plan to take various steps to prevent

overexposure of individuals conducting NAA at your facility. These steps include that

manufacturing holders and manipulators to minimize extremity doses from NAA work,

conducting additional training on NAA and general handling of radioactive materials for

employees, establishing a contractual agreement with your dosimetry provider to ensure that

you receive immediate notification of doses greater than the annual regulatory limits, mounting

a permanent radiation detector in NAA work area, developing specific written procedures on

NAA work, and providing additional dosimetry for those involved in NAA work over the next

several months.

Due to the significance of the potential overexposure event, an NRC inspector was dispatched

to the site and arrived on March 20, 2006. Because of the complicated nature of personnel

monitoring, dosimetry processing, and the apparent incongruent dosimetry results, a Special

Inspection Team was assigned to review the event. The Special Inspection Team began their

review on March 27, 2006.

Based on the results of this inspection, the NRC has determined that a Severity Level IV

violation of NRC requirements occurred. The violation was evaluated in accordance with the

NRC Enforcement Policy. The current Enforcement Policy is included on the NRCs Web site

at www.nrc.gov; select What We Do, Enforcement, then Enforcement Policy. The violation is

cited in the enclosed Notice of Violation (Notice) and the circumstances surrounding it are

described in detail in the subject inspection report. The violation is being cited in the Notice

because the facilitys staff had prior opportunity to identify the problem (on noting the higher

extremity dose to a worker in October 2005), but failed to take action to prevent the event.

Further, the facilitys staff did not thoroughly assess the February 24, 2006, exposure report of

a potential overexposure to identify the root causes of the problem and was too quick to dismiss

it as being anomalous. The violation relates to the failure to provide radiological surveys that

are reasonable under the circumstances to evaluate the magnitude and extent of radiation

levels and the potential radiological hazards.

You are required to respond to this letter and should follow the instructions specified in the

enclosed Notice when preparing your response. The NRC will use your response in

accordance with its policies to determine whether further enforcement action is necessary to

ensure compliance with regulatory requirements.

In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and its

enclosure will be available electronically for public inspection in the NRC Public Document

Room or from the Publicly Available Records (PARS) component of NRCs document system

(ADAMS). ADAMS is accessible from the NRC Web site at (the Public Electronic Reading

Room) http://www.nrc.gov/reading-rm/adams.html.

3

Should you have any questions regarding this inspection, please contact Brian Thomas, Chief,

Research and Test Reactors Branch at 301-415-2170.

Sincerely,

/RA/

Christopher Grimes, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Docket No. 50-128

License No. R-83

Enclosures: 1. Notice of Violation

2. NRC Special Inspection Report No. 50-128/2006-203

cc w/encl.: Please see next page

Texas A&M University System Docket No. 50-128

cc w/encl:

Mayor, City of College Station

P.O. Box Drawer 9960

College Station, TX 77840-3575

Governors Budget and

Planning Office

P.O. Box 13561

Austin, TX 78711

Texas A&M University System

ATTN: Dr. Warren D. Reece, Director

Nuclear Science Center

Texas Engineering Experiment Station

F. E. Box 89, M/S 3575

College Station, Texas 77843

Texas State Department of Health

Radiation Control Program Director

Bureau of Radiation Control

Dept. of Health

1100 West 49th Street

Austin, Texas 78756-3189

Test, Research and Training

Reactor Newsletter

202 Nuclear Sciences Center

University of Florida

Gainesville, FL 32611

Should you have any questions regarding this inspection, please contact Brian Thomas, Chief,

Research and Test Reactors Branch at 301-415-2170.

Sincerely,

/RA/

Christopher Grimes, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Docket No. 50-128

License No. R-83

Enclosures: 1. Notice of Violation

2. NRC Special Inspection Report No. 50-128/2006-203

cc w/encl.: Please see next page

DISTRIBUTION:

PUBLIC PRTA r/f AAdams CBassett

PDoyle TDragoun WEresian DHarrison

DHughes EHylton PIsaac DStarkey

MMendonca JQuichocho WSchuster BThomas

MVoth KWitt PYoung DBarss (MS O6-H2)

BDavis (Ltr only O5-A4) NRR enforcement coordinator (Only for IRs with NOVs, O10-H14)

ACCESSION NO.: ML061090188 TEMPLATE #: NRR-

OFFICE PRT:RI PRT:LA PRT:BC DPR:DIR

NAME CBassett:tls* EHylton* BThomas* CGrimes:tls*

DATE 4/25/06 5/9/06 5/10/06 5/11/06

OFFICIAL RECORD COPY

NOTICE OF VIOLATION

Texas A&M University Docket No.: 50-128

Texas A&M University Nuclear Science Center License No.: R-83

During an NRC inspection conducted on March 27-29, 2006, a violation of NRC requirements

was identified. In accordance with the NRC Enforcement Policy, the violation is listed below:

10 CFR 20.1501(a) requires that each licensee shall make or cause to be made, surveys that:

1) may be necessary for the licensee to comply with the regulations, and 2) are reasonable

under the circumstances to evaluate the magnitude and extent of radiation levels; and

concentrations or quantities of radioactive material; and the potential radiological hazards.

Contrary to the above, the licensee failed to make reasonable surveys to evaluate the

magnitude and extent of shallow dose equivalent radiation levels following the initial trial runs of

vials containing plastic disks and following the first indication of a possible overexposure on

February 24, 2006.

This is a Severity Level IV violation (Supplement IV).

Pursuant to the provisions of 10 CFR 2.201, Texas A&M University is hereby required to

submit a written statement or explanation to the U.S. Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington, D.C. 20555-0001 with a copy to the responsible

inspector, 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; EA-06-113," and

should include for each violation: (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 to avoid further violations, 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 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, D.C. 20555-0001.

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

Public Document Room or from the Publicly Available Records (PARS) component of the

NRCs document system (ADAMS), 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. ADAMS is accessible from the NRC Web site at (the Public Electronic

Reading Room) http://www.nrc.gov/reading-rm/adams.html. 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

Enclosure 1

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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.

In accordance with 10 CFR 19.11, you may be required to post this Notice within two working

days.

Dated at Rockville, Maryland

this day of May 2006

U. S. NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

Docket No: 50-128

License No: R-83

Report No: 50-128/2006-203

Licensee: Texas A&M University

Facility: Texas Engineering Experiment Station

Nuclear Science Center

Location: College Station, TX

Dates: March 27-29, 2006

Inspectors: Craig Bassett

Sami Sherbini

Approved by: Brian Thomas, Chief

Research and Test Reactors Branch

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

SUMMARY OF FINDINGS

Texas A&M University

Texas Engineering Experiment Station

Inspection Report No. 50-128/2006-203

The report covered a period of three days of inspection by two inspectors. The NRCs program

for overseeing the safe operation of research and test reactors is described in Manual Chapter

2545, Research and Test Reactor Inspection Program. A Special Inspection was established

in accordance with NRC Management Directive 8.3, NRC Incident Investigation Program.

The Special Inspection Team charter did not require the team to address compliance or assess

significance of findings and observations. Another inspection will be scheduled to address the

follow-up items identified by the team.

NRC-identified and Self-Revealing Findings

During work involving radioactive material, licensee employees of the Texas Engineering

Experiment Station, Nuclear Science Center (NSC) are required to wear an Optically Stimulated

Luminescent dosimeter for whole body monitoring and a finger ring containing a

thermoluminescent dosimeter chip for extremity monitoring. At the end of January 2006, the

NSC Radiation Safety Officer (RSO) sent the dosimeters used by facility staff personnel to the

dosimetry vendor for processing. The RSO did not receive the dosimetry results report until

February 24, 2006. The report indicated that a worker, who had been conducting neutron

activation analysis (NAA) using the pneumatic transfer system during January, had received a

whole body dose of 0.033 rem and an extremity dose to the hand of 75.8 rem. The NSC

Facility Director and RSO immediately noted the results, restricted the worker from further work

with radioactive material that would contribute to an extremity dose, and began a review of the

situation. After careful consideration of various factors involved, the Director and RSO

determined that this was an anomalous reading and allowed the person to continue restricted

activities, although all the sample processing work for February had been completed at that

point. At the end of February, personnel dosimeters were again gathered and sent to the

vendor for processing. Those dosimetry results, which were received on March 15, 2006,

indicated that the worker conducting NAA using the pneumatic system had received a whole

body dose of 0.006 rem and an extremity dose of 37.54 rem during February. The licensee

notified the NRC of the event on March 15, 2006.

An NRC inspector was dispatched to the site and arrived on March 20, 2006. Because of the

complicated nature of personnel monitoring, dosimetry processing, and the apparent

incongruent dosimetry results, a Special Inspection Team was assigned to review the event.

The Special Inspection Team began their review on March 27, 2006. The team found that the

licensees initial response to the event was less than acceptable. The licensee did not

thoroughly assess the first report of a potential overexposure and was too quick to dismiss it as

being erroneous. Also, there was confusion on the need to report such an event. However, the

team also reviewed the licensees immediate corrective actions, including the dose calculations,

and found those actions to be generally acceptable.

Nevertheless, based on the results of this inspection, the team found that the licensee failed to

conduct acceptable surveys of the sample vials of irradiated material when a NAA experiment

involving the pneumatic system was first initiated, failed to train and monitor a worker on

handling sample vials with his hands/fingers, and failed to conduct surveys of the sample vials

of irradiated material following the first indication of a possible overexposure on February 24,

2006, to determine the cause of the problem which together lead to a substantial increase in

the extremity exposure of one worker at the facility.

Enclosure 2

REPORT DETAILS

1. Introduction

a. Event Description

The licensees research and test reactor (RTR) is operated under the authority and

administration of the Deputy Director of the Texas Engineering and Experiment

Station (TEES). The RTR is located in the Nuclear Science Center (NSC) and is

managed by the Director of the NSC and his staff. Daily operations activities are

conducted under the supervision of the Associate Director, while the support activities,

including radiation protection, are overseen by the Radiation Safety Officer (RSO).

One of the projects in progress during January was neutron activation analysis (NAA)

of small plastic disks using the facility pneumatic transfer system. During this work

involving radioactive material, licensee employees are required to wear an Optically

Stimulated Luminescent (OSL) dosimeter for whole body monitoring and a finger ring

containing a thermoluminescent dosimeter (TLD) chip for extremity monitoring.

At the end of January, the licensee sent the dosimeters used by all employees who

worked at the NSC during the month to the dosimetry vendor for processing. The

licensee did not receive those dosimetry results until February 24, 2006. The results

indicated that one employee, who will be referred to in this report as Worker A, had

received a whole body dose (or deep dose equivalent (DDE)) of 0.033 rem and an

extremity dose (or shallow dose equivalent (SDE)) of 75.8 rem. The individual, who

had been conducting NAA work using the pneumatic transfer system, was immediately

prohibited from any work which could cause an increase dose to the extremities.

Upon receiving the dosimetry report, the RSO began a review of the situation. The

licensee determined that processing these NAA samples was a standard procedure

that had been conducted numerous times over the past year and nothing in the

process had changed. While Worker A had not been the primary person responsible

for NAA processing in the past, he had assisted in the procedure many times during

the previous six months and was trained on, and familiar with, the operation. The

licensee also noted that the dosimetry processor had, on occasion in the past,

supplied erroneous dosimetry reports to the facility, including a high reading for an

individual who had not used his dosimeter for several months. After consideration of

the circumstances fo the event, the licensee concluded that this was an anomalous

reading and prepared a dose assessment report based on the average extremity dose

of the individual from the past three months. Worker A was placed on restricted duty

and allowed to return to work although all the NAA samples for the testing period had

already been processed.

At the end of February, the dosimeters were again gathered and sent to the vendor for

processing. The licensee received those dosimetry results on March 15, 2006, which

indicated that Worker A had received a DDE of 0.006 rem and a SDE of 37.54 rem.

The licensee notified the NRC of the event on March 15, 2006. However, because the

next two days and the following weekend were scheduled as Spring Break for the

University, no one was available at the facility during Thursday or Friday. An NRC

inspector was dispatched to the site and arrived the morning of Monday, March 20,

2006. Because of the numerous questions involved with the dosimetry aspects of the

event, a Special Inspection Team was subsequently formed and began their review of

the potential overexposure on March 27, 2006.

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b. Background and Chronology of Work Activities

As noted above, the licensee had been processing these NAA samples using the

pneumatic transfer system at the facility for approximately one year. Another person,

Worker C, had been the primary person who had handled the samples during 2005. A

third person, Worker B, also performed the work of handling the samples on occasion.

Worker A had been assisting as needed with this work for about six months. During

2005, neither Worker B nor Worker C had received extremity doses of the magnitude

received by Worker A in January and February 2006. The highest extremity dose

during 2005 was 1.58 rem and was received by Worker C. The most recent numbers

of samples, the period of time worked, and the finger ring TLD readings are shown

below in Table 1.

Table 1

Employee Number of Samples and Period of Time TLD Results,

Types of Material rem

Worker C 226 (silicon (Si)) October 2005 1.58

Worker C 240 (Si and silver (Ag)) November 2005 0.88

Worker B 88 (NIST Ag) December 2005 0.08

Worker B 195 (Ag and iodine (I)) January 10-27, 2006 0.18

Worker A 140 (Ag) January 17-30, 2006 75.8

Worker A 141 (Si, Ag, and I) February 6-22, 2006 37.54

Worker A 0 March 1-23, 2006 0.04

As will be detailed below, during January and February 2006, Worker A also helped

complete one radioactive material shipment, conducted various routine surveys, and

performed routine calibrations of counting instruments. Again, other licensee

employees also helped with and/or completed the same or similar tasks during this

same time period.

2. Event Follow-up - Sequence of Events

a. Inspection Scope

The inspectors interviewed licensee personnel, observed tests conducted by the

licensee, and reviewed various logs, dose calculations, and other documentation to

develop the following sequence of events leading up to and following the potential

overexposure.

b. Observations and Findings

Date Event Description

01/01-16/2006 Worker A was out of the country on vacation.

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01/17-30/2006 Worker B processed 195 Ag- and I-samples using the pneumatic

transfer system.

01/17/2006 Worker A processed 21 Ag-samples using the pneumatic system.

01/23/2006 Worker A processed 34 Ag-samples using the pneumatic system.

01/24/2006 Worker A completed the shipping surveys and the associated

paperwork for a radioactive material shipment consisting of shielded

containers of Argon-41 (Ar-41).

01/25/2006 Worker A processed 41 Ag-samples using the pneumatic system.

01/30/2006 Worker A processed 44 I-samples using the pneumatic system.

01/31/2006 Worker A and Worker B completed the monthly Facility Air Monitoring

(FAM) test using a source containing 4.68 nanocuries (nCi) of

Technetium-99 (Tc-99) and a source containing ~22.5 millicuries

(mCi) of Cobalt-60 (Co-60).

02/01-02/2006 The licensee collected facility personnel dosimeters used during

January and mailed them to the dosimetry processor for processing.

02/06/2006 Worker A processed 51 I-samples using the pneumatic system.

02/07/2006 Worker A processed 15 I-samples using the pneumatic system.

02/13/2006 Worker A assisted two other individuals in completing the Channel 6

Building Gas Monitor calibration which involved setting up tubing

which passed Ar-41 gas through the gas monitor detector.

02/15/2006 Worker A processed 27 Si-samples using the pneumatic system.

Worker A completed calibration of the sample counters using the

source containing 4.68 nCi of Tc-99 and completed the calibration of

the alarming rate meters using an electronic pulser and a small check

source (containing <10 microcuries of Cesium-137 (Cs-137)).

02/21/2006 Worker A processed 24 I-samples using the pneumatic system.

02/22/2006 Worker A processed 24 I-samples using the pneumatic system.

02/24/2006 The licensee received the results from the dosimetry processor which

indicated that Worker A had received a dose to the extremities of

75.8 rem.

The worker was suspended from working with pneumatic samples

and an investigation was begun immediately.

-4-

02/27/2006 Worker A and Worker B completed the monthly FAM test using a

source containing 4.68 nCi of Tc-99 and a source containing ~22.5

mCi of Co-60.

The licensee contacted the dosimetry vendor to confirm that the

finger ring dosimeter results were accurate.

02/28/2006 Worker A completed a radiation and contamination survey of the

Material Handling Area and calibrated the instrument to be used to

count the swipes using a check source containing 4.68 nCi of Tc-99.

03/01-02/2006 The licensee collected facility personnel dosimeters used during

February and mailed them to the dosimetry processor for processing.

03/06/2006 Worker A processed 7 background samples using the pneumatic

system. Worker A also helped process 8 nautical archeology

samples for a student lab.

03/07/2006 Worker A helped process 14 nautical archeology samples for a

student lab.

03/09/2006 Worker A helped process 13 gold (Au) foil samples for a student lab.

03/15/2006 The licensee received the results from the dosimetry processor which

indicated that Worker A had received a dose to the extremities of

37.54 rem.

The NRC was notified immediately and an investigation of the event

begun.

03/16-19/2006 Texas A&M University spring break.

03/20/2006 An NRC inspector arrived on site to conduct a preliminary review of

the potential overexposure and conduct a routine inspection.

The inspector observed a time-motion study of pneumatic sample

handling performed by Worker A to determine the length of time his

hands were in contact with each sample. The time was measured as

15 seconds per sample.

03/21/2006 The licensee initiated extremity dose calculations using the computer

code VARSKIN - Mod2 and also using a separate computer code

MCNP model.

The licensee again contacted the dosimetry vendor to confirm that the

finger ring dosimeter results were accurate.

03/22/2006 The inspector observed as Worker D processed two Ag-samples

using the pneumatic transfer system and measured the dose rates

from the various components with an open-window ion chamber. The

results were as follows in Table 2:

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Table 2

Items Contact Reading

Outer vial (with foam and inner vial) 2.6 Roentgen per hour (R/hr)

Foam cushioning material separately 470 mR/hr

Outer vial separately 26 mR/hr

Inner vial (with plastic disk sample) 2.4 R/hr

From these measurements and using a volume correction factor of

10, the licensee calculated a dose to the extremities from processing

140 pneumatic samples of 20.22 rem.

03/23/2006 Initial licensee dose estimates using VARSKIN - Mod2 indicated a

worst case beta dose to the extremities from processing 140

pneumatic samples of 17.46 rem.

03/24/2006 Initial dose modeling using MCNP resulted in a dose estimate to the

extremities from processing 140 pneumatic samples of 9.94 rem.

03/25/2006 The inspector observed the calibration of 15 TLD chips using a known

source of radiation against a NIST traceable Farmers ion chamber.

03/26/2006 The inspector observed as the 15 TLD chips were processed to

determine the dose received. The TLD chips were then annealed in

anticipation of using them in another test on Monday.

03/27/2006 A Special Inspection Team arrived on site to conduct a review of the

potential overexposure and the licensees response.

The licensee received the results from the dosimetry processor

indicating that the extremity exposure received by Worker D during

the re-enactment of sample handling was not measurable.

The team observed a test conducted by the licensee to expose (for

one minute) a set of 6 TLDs to an irradiated sample vial processed in

a similar manner as those that had been processed during January

and February. Two TLD chips were placed so as to be in contact with

the source at the side of the sample vial. This test was conducted

twice with two different sets of TLDs. Two vendor finger rings were

also exposed to the sample sources (placed in contact with the vials

for one minute) and subsequently sent to the vendor for processing.

-6-

The NRC began calculating a potential extremity dose using

VARSKIN to estimate a worst case beta dose from processing 140

pneumatic samples.

03/28/2006 The inspectors observed as the TLD chips, which had been exposed

to the sample vials on March 27, were processed to determine the

dose received.

Dose estimates using the dose numbers derived from the exposure of

the TLD chips indicated a dose to the extremities from processing

140 pneumatic samples of approximately 24.7 rem.

The licensee again contacted the dosimetry vendor to discuss the

finger ring dosimeter results and to obtain information on the vendors

processing procedures and techniques.

The NRC began modeling the event scenario using MCNP to obtain a

second estimate of the worst case extremity dose from processing

140 pneumatic samples.

03/29/2006 The dosimetry processor provided results for the two finger rings that

were sent indicating a dose of 0.39 rem for one minute exposure on

one ring and 0.46 rem for one minute exposure on the other. This

would result in a worst case extremity exposure of 16.1 rem from

processing 140 samples.

The inspectors observed a re-enactment by Worker A of the sample

handling technique concentrating on the time required to transport the

sample from the pneumatic transfer area to the counting area. The

average time was 12 seconds.

03/30/2006 Worker A was sent for a medical examination. The doctor found no

problems or abnormalities. Consultation with another specialist was

scheduled by the first doctor. A follow-up exam was scheduled for

April 27, 2006.

c. Conclusions

Based on the records reviewed, following notification of a potential overexposure, the

licensee restricted the individual with the potential extremity overexposure from

handling NAA pneumatic samples. However, the sample handling work for the period

had been completed at that point.

3. Procedures and Training

a. Inspection Scope (IP 69001)

The inspectors reviewed selected aspects of the following to verify compliance with TS Section 6.3 concerning facility procedures:

-7-

Pneumatic System Training Module

Facility records for pneumatic system and radiation worker training

Reactor Safety Board (RSB) meeting minutes from 2004 through the present

NSC Standard Operating Procedure (SOP),Section I, Procedure D, Format,

Rev. 3, dated February 25, 2002

NSC SOP,Section I, Procedure E, Origination, Rev. 1, dated February 25, 2002

NSC SOP,Section I, Procedure F, Review and Approval, Rev. 1, dated

February 25, 2002

NSC SOP,Section I, Procedure G, Distribution and Binding, Rev. 0, dated

July 31, 1986

NSC SOP,Section IV, Procedure C, Pneumatic System Operation, Rev. 0,

dated February 8, 1991

NSC SOP Section VII, Procedure A-3, Reporting Requirements, Revision 2,

dated December 19, 1997

NSC SOP Section VII, Procedure A-5, Annual Review of SOP Section VII (HP

Procedures), Revision 3, dated August 19, 2003

NSC SOP Section VII, Procedure A-6, ALARA, Revision 0, dated December 12,

2002

NSC SOP Section VII, Procedure C-10, Radioactive Materials Handling,

Revision 2, dated December 19, 1997

NSC Form 595, Procedure Change Notice (PCN), latest revision dated

January 31, 2005

NSC Form 844, Radiation Work Permit, Number (No.) 005, Revision (Rev.)

No. 05-0, dated November 15, 2005

Texas A&M University, Nuclear Science Center, Pneumatic System Training

Module, Rev. dated January 10, 2001

Texas A&M University, Nuclear Science Center, Radiation Worker Training

Module, no revision date

b. Observations and Findings

The inspectors reviewed various NSC SOP Sections and selected procedures. These

SOP Sections and procedures provided guidance for the administrative, operations,

and health physics functions of the facility. The inspectors confirmed that written

procedures were available for those tasks and items required by TS Section 6.3. The

licensee controlled changes to procedures and the RSB conducted the review and

approval process as required.

The inspectors also reviewed the procedures, Radiation Work Permit (RWP), and

training modules that were related to the potential overexposure event. It was noted

that, although the procedures and training modules gave guidance and instruction on

the general use and handling of radioactive material, very little specific information

was included on use of survey meters during processing samples and on remote

handling of radioactive material and the use of tongs or other tools to provide distance

and/or shielding from a potential source of radiation. Licensee personnel indicated

that such issues were generally taught and discussed in class. It was also noted that

facility staff members were not forbidden from using their hands for a brief period to

perform some functions such as removing the inner sample vial from the outer vial if

the dose rates allowed. The licensee was informed that the issue of ensuring that

-8-

sufficient guidance and instruction on the proper handling of radioactive material was

an area for improvement and would be followed by the NRC as an Inspector Follow-up

Item (IFI) (IFI 50-128/2006-203-01).

(The issue of proper handling of radioactive material will be addressed in more detail

in Section 5 of this report.)

The inspectors also reviewed the 2005 training records and interviewed NSC staff

members concerning the training received at the facility. The inspectors determined

that the training of personnel on procedures and general Radiation Worker and

ALARA training was acceptable, although as discussed above that specific guidance

and instructions will be the subject of future inspector follow-up actions.

c. Conclusions

Based on the procedures and records reviewed and observations of NSC staff during

the inspection, the inspectors determined that the procedural control and

implementation program was acceptably maintained. Procedures, RWPs, and the

training program could be improved with respect to radioactive material handling and

the use of tools and shielding devices.

4. Licensee Investigation of and Response to the Event

a. Inspection Scope

The inspectors reviewed the following concerning the licensees response to the event

to ascertain compliance with 10 CFR 20.2202(b)(1)(iii):

Pneumatic System Training Module

C various licensee records and E-mails

RSB meeting minutes from 2004 through the present

Personnel dosimetry records for 2005 through the present

RSB completed audits and reviews from 2004 through the present

Facility records for pneumatic system and radiation worker training

Annual Report for the Texas A&M University Nuclear Science Center for 2004

various forms associated with the procedures mentioned below for 2005

C NSC Safety Evaluation for the Use of Pneumatic Transfer Systems, undated

C NSC Form 111, Experiment Authorization, Pneumatics Transfer System

Irradiations, dated January 1, 1989

NSC SOP Section VII, Procedure A-1, Radiation Protection Program, Rev. 3,

dated December 4, 1997

NSC SOP Section VII, Procedure A-3, Reporting Requirements, Rev. 2, dated

December 19, 1999

NSC SOP Section VII, Procedure A-6, ALARA, Rev. 0, dated February 25, 2002

NSC SOP Section VII, Procedure B-14, Personnel Dosimeters, Rev. 6, dated

October 15, 1999 and Procedure Change Notice (PCN) dated August 28, 2002

NSC SOP Section VII, Procedure C-10, Radioactive Materials Handling, Rev. 2,

dated December 19, 1997

-9-

NSC SOP Section VII, Procedure D-1, Health Physics Training, Rev. 0, dated

October 3, 1990

NSC SOP Section VII, Procedure E-1, Personnel Dosimetry, Rev. 0, April 13,

1995

b. Observations and Findings

(1) Initial Notification of Potential Overexposure

10 CFR 20.2202(b) states, in part, that: Each licensee shall, within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of

discovery of the event, report any event involving loss of control of licensed

material possessed by the licensee that may have caused, or threatens to cause,

any of the following conditions: (1) An individual to receive, in a period of 24

hours [empahsis added]-. . . .(iii) A shallow-dose equivalent to the skin or

extremities exceeding 50 rems (0.5 Sv) . . . .

The licensees response upon receiving the first dosimetry report, for the January

2006 period, was to restrict Worker A from work that would result in extremity

exposure. At the time this action was taken Worker A had already worked most

of the following period, February 2006, because the report for January was

received toward the end of February. The licensee also initiated an investigation

of the work performed by Worker A to determine if there was anything unusual

that may have contributed to the high dose, but none was found. The licensee

stated that in the past, dosimetry reports have occasionally shown high readings

that were later proven to be false and, because their investigation did not, at first,

reveal anything unusual in this case, they believed the reading to be false, and

did not report the initial dosimetry results to the NRC.

The licensee immediately notified the NRC upon receipt of the second report

containing an unusually high reading for the same worker. Although these

responses by the licensee are generally acceptable, the NRC must be notified of

any conditions that conform to the notification and reporting requirements in Part

20, even in the face of great uncertainty regarding the validity of the data, as was

the case in this event. The licensee did not notify the NRC after receiving the first

high dosimetry report even though the dose reported was substantially above the

limit. As noted above, they evaluated the problem and reached the conclusion

that the 75.8 rem dose was erroneous. Although the dose was not likely to have

been received in 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , the conservative action would have been to report.

Because the licensee did not report the potential overexposure as required by the

regulations, the licensee indicated that Event Notification to the NRC will be

carefully evaluated for the future so that proper notifications are made in a timely

manner. The licensee was informed that review of the Event Notification

procedure would be followed by the NRC as an IFI and would be reviewed by the

NRC during a future inspection (IFI 50-128/2006-203-02).

It was noted that, following the receipt of the dosimetry report on February 24,

2006, the licensee did not conduct any type of surveys of sample vials containing

irradiated material to determine the potential dose that could be received by a

-10-

person handling the material. Based on their review of the employees work

duties and assignments, his previous dose history, and the extremity dose to the

hands that had been received by another worker, who had handled samples in

January, the licensee decided that a calculated dose assessment was needed for

the employee. This NRC determined that the licensee did not do as thorough a

job as they could have in investigating the first reported high dosimeter reading

(for January). The issue of not conducting a proper evaluation of the event was

noted as a problem by the NRC and will be discussed further later in the report.

(2) Second Notification of Potentially High Dose to the Extremities

On March 15, 2006, the licensee received the results from the dosimetry

processor which indicated that Worker A had received a dose to the extremities of

37.54 rem during February. The Facility Director and RSO reviewed the results

and the NRC was notified immediately.

After licensee personnel returned to work on Monday, March 20, they began an

intensive investigation into the cause of the apparent extremity overexposure.

The Facility Director and the Radiation Safety Officer (RSO) investigated several

possibilities. These included the following:

- Reiterated the restriction that Worker A was not to be involved in handling

any radioactive samples or any work that would cause further dose to the

extremities.

- Reviewed the dosimetry records of everyone who had been involved in the

NAA project for the past 12 months.

- Conducted various interviews with the individual involved in the apparent

overexposure to determine exactly what the individual had done for the

months of January and February of 2006. (These activities are summarized

in Paragraph 2 - Sequence of Events above.)

- Determined the number of samples processed by the individual during those

months. During January, the individual processed 140 samples and during

February, 141 samples.

- Conducted time-motion studies on the pneumatic sample processing. The

licensee concluded that each sample was handled for approximately 15

seconds.

- Completed various test runs of samples to verify the beta and gamma dose

rates on the vials and foam after the end of irradiation (EOI) and about five

seconds after the sample was returned to the lab. Separate radiation

readings were taken of the outer vial containing all the enclosed components,

the outer vial by itself, the foam packing used to cushion the inner vial, and

the inner vial containing the small plastic disk sample. (The readings noted

are given in Paragraph 2 - Sequence of Events above.)

- Calculated doses to the extremities based on the time-motion studies and the

dose rates noted from the various tests that they conducted. (The initial

estimates are given in Paragraph 2 - Sequence of Events above and are

summarized in a table in Paragraph 6.b.(4) below.)

-11-

- Contacted the customer to ascertain whether or not the composition of the

samples had changed. The licensee was informed that the composition of

the plastic disks being tested had not changed.

- Reviewed the analyses of the samples run during January and February to

determine whether or not the relative quantities of the various isotopes noted

in the samples had changed. No changes were noted and all samples

contained relatively the same quantities of isotopes. Typical quantities

included 90 microcuries (FCi) of Ag-108 and 15 FCi of I-128.

- Reviewed the location where all employees dosimeters are stored. The

individual involved indicated that he always placed his dosimeter and finger

ring in the storage rack, as did all other employees. No problems were

noted.

- Reviewed the use and storage of the various sources that are maintained at

the facility. No anomalies were noted.

- Contacted the dosimeter vendor to request that the doses for January and

February be checked and reevaluated. The vendor indicated that the

processing and calculations were correct and forwarded the resulting glow

curves to the licensee.

- The licensee reviewed the dosimeter results of others who had handled the

samples and noted that another person, Worker B, had also used the

pneumatic transfer system during January but had received an extremity

dose of 0.18 rem and had handled more samples than Worker A.

- Sent Worker As finger ring used during March to the dosimetry process for

emergency processing. The results indicated an exposure of 0.040 rem for

March.

- Using MICROSHIELD, calculated the gamma dose rates that Worker A

received to the extremities during January and February. The results would

not significantly increase the persons dose.

(3) Corrective Actions Taken or Planned

The licensee has taken various actions to improve their radiation protection

program. One of these actions, which was in fact initiated before this incident,

was to develop a plastic jig that is to be used to hold the sample vial while the

workers cuts off the top. This will prevent any direct handling of the vials by the

workers hands. A tool will also be used to permit quicker cutting than is

achievable using a razor blade. The jig was ready for use at the time of this

inspection, but had not yet been adopted for routine use. The licensee also

stated that they will be holding training sessions for all of their workers to describe

this incident and to instruct them on the proper handling of the samples and the

use of the jig. The radiation safety program at the facility, including sample

monitoring and contamination control practices, were otherwise found to be

acceptable for the type of radiation work conducted at the facility.

In addition, the licensee has also taken or plans to take the following actions as a

result of the exposure event:

-12-

Corrective Action Completed

- Restricted the individual from working with any pneumatic system samples or

doing work that would cause an extremity dose.

- Conducted a separate study of the pneumatic system sample handling

process using another individual and had that persons finger ring analyzed

after two sets of samples were processed. Those results indicated a

minimum dose.

- Held a meeting on Thursday, March 30, for the NAA pneumatics-trained

personnel to review the event and review the subjects of ALARA, radioactive

material handling, and the use of the newly developed tools and beta shields.

- Worker A was sent for a medical examination on Thursday, March 30. The

doctor found no problems or abnormalities. A follow-up exam was scheduled

for April 27, 2006.

- An RSB meeting was held on April 13, 2006, to review the event.

- Worker As was reclassified as a Non-Rad Worker and will no longer be

issued dosimetry (at least for the remainder of this year).

Corrective Action Planned

- Hold a meeting for all NSC personnel to review the event and review the

subjects of ALARA, radioactive material handling, and the use of tools, tongs,

and beta shields.

- Plan to issue two finger ring badges to each NAA worker and send the finger

rings to the vendor for processing every two weeks, instead of every month,

for the next three months.

- Lock the storage cabinets containing the sources at the facility.

- Revise the training program on radioactive materials handling.

- Initiate a program for the NSC Director and/or the RSO to observe work

practices on a regular basis to note good and bad practices and correct any

problems noted.

- Review the SOP for radioactive material handling and consider special

handling procedures in the laboratories.

- Event Notification to the NRC will be carefully evaluated for the future so that

proper notifications are made in a timely manner.

- Reassess the dosimetry vendors response and licensee needs for reliable

and rapid information on potential overexposures.

- Work with the dosimetry vendor to ensure that E-mail can and will be sent

following any indication of an overexposure after the vendor processes the

OSL or TLD badges.

- Plan to permanently install a radiation detector inside the Fume Hood near

the point where the pneumatic transfer system tube ends.

The licensee was informed that the corrective actions taken will be followed by

the NRC as an IFI and will be reviewed during a future inspection (IFI 50-

128/2006-203-03).

-13-

c. Conclusions

Even though the licensee concluded that it was not valid, they did not take the

conservative action to notify the NRC within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of receiving notification of a

possible extremity overexposure. The licensee did not do as thorough a job as they

could have in investigating the first reported high dosimeter reading (for January).

The licensees subsequent corrective actions, including the dose calculations, were

found to be acceptable.

5. Root Cause Determination and Related Contributing Actions

a. Inspection Scope (IP 69001)

The inspectors reviewed selected aspects of the following to verify compliance with

10 CFR Parts 19 and 20 and TS Sections 3.5, 4.5, 5.4, and 6.6 requirements:

Licensee records and E-mails

Licensee dose calculations and test data

RSB meeting minutes from 2004 through the present

Personnel dosimetry records for 2005 through the present

RSB completed audits and reviews from 2004 through the present

Facility records for pneumatic system and radiation worker training

Personnel dosimetry records for facility personnel for 2005 to date

Annual Report for the Texas A&M University Nuclear Science Center for 2004

various forms associated with the procedures mentioned below for 2005

C NSC Safety Evaluation for the Use of Pneumatic Transfer Systems, undated

C Experiment Authorization No. E-2-1, Pneumatics Transfer System Irradiations,

dated January 1, 1989

NSC SOP,Section IV, Procedure C, Pneumatic System Operation, Rev. 0,

dated February 8, 1991

NSC SOP Section VII, Procedure A-3, Reporting Requirements, Revision 2,

dated December 19, 1997

NSC SOP Section VII, Procedure A-6, ALARA, Revision 0, dated December 12,

2002

NSC SOP Section VII, Procedure C-10, Radioactive Materials Handling,

Revision 2, dated December 19, 1997

NSC Form 844, Radiation Work Permit, Number (No.) 005, Revision (Rev.)

No. 05-0, dated November 15, 2005

Texas A&M University, Nuclear Science Center, Pneumatic System Training

Module, Rev. dated January 10, 2001

Texas A&M University, Nuclear Science Center, Radiation Worker Training

Module, no revision date

b. Observations and Findings

(1) Licensee Root Cause Determination

The licensee initially concluded that, based on the calculations and

measurements made, even in full contact with the NAA sample vial (the source),

-14-

doses reported by the dosimetry processor could not be reached. The licensee

indicated that the original dosimetry results were most likely overly conservative.

Considering the sources available at the NSC, it was not known how such high

extremity doses could be received in a one month period. However, after more

consideration, the licensee determined that the root cause of the event was failure

to follow procedure in that Worker A apparently handled the sample vials in a

different manner than any of the other workers had and held the sample vial in his

hands as opposed to touching it briefly while cutting the end off.

The licensee also noted that no other employee had ever received hand doses

unexpectedly, especially at the levels reported in this event. No other work had

ever produced such hand doses, nor should it be possible if procedures are

followed. The licensee conjectured that the possibility remained that the rings

were removed and placed next to a source for an extended period of time.

However, Worker A did not recall any such circumstance.

(2) NRC Root Cause Investigation

10 CFR 20.1501(a) requires that each licensee shall make or cause to be made,

surveys that: 1) may be necessary for the licensee to comply with the

regulations, and 2) are reasonable under the circumstances to evaluate the

magnitude and extent of radiation levels; and concentrations or quantities of

radioactive material; and the potential radiological hazards.

The inspectors reviewed the licensees review and associated actions following

the initial proposal to conduct the NAA experiments on the clients plastic disks. It

was noted that this experiment was conducted under Experiment Authorization

(EA) No. E-2-1, Pneumatic Transfer System Irradiations, dated January 1, 1989.

The EA, the associated Safety Evaluation, SOP IV-C, Pneumatic System

Operation, and the Pneumatic System Training Module, provided general

guidance on using the system and how to handle a sample once it returns from

being irradiated in the reactor. Those instructions included checking the sample

with an ionization chamber before removing it from the pneumatic system and

handling the sample carefully because of external contamination concerns. None

of the aforementioned documents required that the initial samples run under a

new experiment be surveyed in detail to determine the extent of radiation hazards

that might be present. The licensee indicated that surveys were taken and that

the radiation levels were known but that no survey documentation was made, i.e.,

no survey results were available to document surveys that were reportedly

conducted during the initial trial runs of the sample vials containing plastic disks

after irradiation. It was noted that no procedural steps were written and no

engineering controls were implemented to ensure that occupational doses would

not be adversely affected. The failure to make adequate surveys to fully establish

the radiological hazards that were present following the initial trial runs of vials

containing plastic disks was determined to be a root cause of the problem.

Contributing factors were considered as well. The most apparent factor was the

improper handling of the sample vials in that Worker A handled the sample vials

with his hands. Tongs were provided for use in handling the vials but their use

-15-

was not mandatory. Although the practice of using ones hand/fingers to handle

the sample vials was not prohibited by facility procedure, and indeed allowable as

taught during pneumatics system training, the handling was only supposed to be

for a brief period and at the opposite end of the vial from where the sample was

located. During a demonstration, Worker A held the sample vials in a different

manner than taught or intended by management and apparently in a different

manner than other workers. Typically, workers held the vial close to the top,

away from the source, with the finger tips, while handling. Worker A, however, at

least during the demonstration, grasped the vial with his fingers folded around it,

with the vial resting against his palm, while handling and cutting off the end cap.

The training and monitoring of these activities did not prevent or identify in a

timely manner this improper handling of the sample by Worker A and resulted in a

significantly increased dose to the extremities.

An additional contributing factor was failure to follow procedure. The procedure

requires that the person processing the samples measure the samples with a

portable radiation survey instrument after the samples return from being irradiated

in the reactor core. During an interview with Worker A, the individual admitted

that he did not monitor each sample upon its return. His practice was to look at

the survey meter that was placed just outside the Fume Hood and adjacent to

some shielding that was near the pneumatic transfer system return tube. When

the sample vials arrived back in the Fume Hood return tube, the worker would

glance at the meter and, if there were no high readings, he would pick up the

sample vial for further processing. This practice may have resulted in the worker

picking up the vials too soon after they returned from being irradiated in the

reactor core.

The NRC concluded that: failure to make adequate surveys to fully establish the

radiological hazards that were present following the initial trial runs of vials

containing plastic disks and failure to conduct surveys of the sample vials of

irradiated material following the first indication of a possible overexposure on

February 24, 2006, to determine the cause of the problem lead to failure to

acceptably train and monitor workers regarding the handling of sample vials with

their hands/fingers (VIO 50-128/2006-201-04).

c. Conclusions

The licensee determined that the root cause for this event was failure to follow

procedure. The NRC determined that failure to conduct an acceptable survey of the

sample material when the experiment was first initiated was the root cause of the

problem that lead to a potential overexposure. The lack of initial surveys, as well as,

allowing workers to handle sample vials which lead to improper sample handling by

Worker A and failure to follow procedure were contributors to a violation of the

regulations.

6. Dose Assessment

a. Inspection Scope (IP 69001)

The inspectors reviewed selected aspects of the following to verify compliance with

10 CFR Parts 19 and 20 and TS Sections 3.5, 4.5, 5.4, and 6.6 requirements:

-16-

various licensee records and E-mails

licensee dose calculations and test data

personnel dosimetry records for facility personnel for 2005 to date

b. Observations and Findings

The routine personnel dosimetry used at this facility for workers handling irradiated

samples consists of one whole body dosimeter to monitor whole body and eye doses,

and one finger ring dosimeter to monitor hand exposures. The whole body dosimeter

is an OSL dosimeter, and the finger ring dosimeter consists of a standard TLD chip,

suitably encapsulated and encased in a plastic ring that can be worn on one of the

workers fingers. Workers are instructed to wear the finger ring dosimeter facing the

radiation source and on the finger likely to receive the highest dose. The dosimetry

change period at the facility is monthly. The licensee received the first unusual

dosimetry report from the dosimetry processor on February 24, 2006, and the report

was for the period January 1, 2006 to January 31, 2006. All of the results in the report

were within the expected range except for the affected worker, referred to in this

report as Worker A. This workers whole body dosimeter showed a DDE of 0.034 rem,

which is within the expected range for the type of work he performed, but the SDE was

reported to be 75.8 rem. This result was well outside the normal range, the history of

the facility indicating that SDE have not previously exceeded about 1.5 rem for a

badging period. The licensee restricted Worker A from further radiation work,

conducted a review of the workers activities, and performed bounding calculations.

The calculations indicated that the activities in which Worker A had engaged in during

the month could not have delivered that high a dose. Having previously encountered

erroneous dosimetry reports from the vendor, including a high reading for a dosimeter

used to monitor background in a reception area, the licensee concluded that the high

reading was erroneous, and was preparing to contact the dosimetry processor to

discuss the case. Before that was done, however, the dosimetry report for the period

February 1, 2006 to February 28, 2006.

As in the previous months report, the DDE for Worker A, 0.006 rem, was low, as

expected, but the SDE was 37.54 rem, again far higher than expected. The licensee

immediately notified the NRC of a potential exposure above the applicable regulatory

limit and initiated a more thorough investigation of both the January and February high

readings. The dosimetry processor did not immediately report either of the high

readings to the licensee, as is usual good practice when an unusual dosimetry result is

obtained during processing.

(1) Re-enactments

Following initiation of an NRC inspection, and before the start of the NRC special

inspection, an NRC inspector observed Worker A re-enacting the type of radiation

work he had been performing during the months of January and February. The

work consisted the following steps:

1. Retrieve the plastic vial containing the irradiated sample from the reactors

pneumatic system.

2. Survey the sample for radiation levels.

-17-

3. Cut of the top of the plastic vial, which had been heat-sealed, using a razor

blade.

4. Retrieve the inner plastic vial that contains the irradiated sample.

5. Place the inner vial containing the sample in a small glass vial and count on a

high-resolution gamma spectroscopy system to identify the activated

radionuclides in the sample and quantify their activities.

These steps were the usual steps followed by all the workers engaged in this type

of work. However, one unusual feature was noted in the manner in which Worker

A cut the tops off of the vials with the razor blade. Normally, the worker would

hold the vial close to the top, away from the source, with the finger tips, while

cutting. Worker A, however, grasped the vial with his fingers folded around it,

with the vial resting against his palm, while cutting. He is left handed, and the vial

was grasped with the right hand. The finger ring was also worn on the right hand,

with the sensitive element facing the palm side of the hand, almost directly

opposite the activated sample. This manner of wearing the finger ring dosimeter

conforms to recommended monitoring practices for the facility. During the re-

enactments, it was found that he held the vial in this position for an average of 15

seconds per sample. Records indicated that he had handled 140 samples during

each of the two months in question.

(2) Experimental Dose Estimates

Order of magnitude calculations performed by the licensee as well as by NRC of

the doses that may arise from the samples showed that the reported SDEs of

75.8 and 37.54 rem could not have been due to photon emissions from the

samples. The activities in the samples were of the order of 100 µCi for one of the

activated radionuclides, and far less for the other activated components. The

estimated doses resulting from the photon emissions from such activity levels

were several orders of magnitude lower than the values that could account for the

high SDE dosimeter readings. It was therefore tentatively concluded that, if the

dosimeter readings were not erroneous, they were probably caused by beta

emissions from the samples. The total thickness of the two plastic vial walls plus

a surgical glove worn by the worker is about 0.25 cm, and beta radiation with

energies above about 0.6 MeV will penetrate this thickness of plastic material.

The beta emissions from nearly all of the activation products in the samples were

sufficiently energetic that significant fractions of their energy spectra fell above

0.6 MeV.

In an attempt to quantify the dose rates from the vials, several samples identical

to the ones handled by Worker A were irradiated in the reactor during the NRC

inspection, for the same length of time, namely four minutes, as that used during

routine irradiations. Upon removal from the pneumatic system, each sample vial

was placed on a bench and a set of TLD chips were held against the wall of the

vial for a period of approximately one minute. Six chips were used in each test,

distributed along the length of the vial to obtain an axial dose distribution. Two of

these chips were placed opposite the irradiated sample, which is the location

expected to yield the highest dose rate. In addition, a finger ring dosimeter was

also placed against the vial wall opposite the activated sample. The TLD chips

-18-

were stored overnight to permit unwanted parts of the glow curves to decay away

(standard procedure), and were read by the licensee the following morning. The

finger ring dosimeters were sent to the dosimetry processor for emergency

processing. The licensee operates a TLD chip reader system calibrated using

radiation measuring detectors traceable to the National Institute of Standards and

Technology (NIST). The dose rates obtained from these experimental

measurements are shown in Table 3 below.

Table 3

Location of Chip Dose Rate - mrad/min Location of Chip Dose Rate - mrad/min

1 38.2 7 42.6

2 81.4 8 104.3

3 419.9 9 681.0

4 1115.4 10 622.0

5 180.4 11 187.4

6 23.2 12 18.2

The readings are all corrected for background. Chips #1 and #7 were close to the

top of the vial, Chips #2 and #8 were about halfway along the length of the vial,

chips #3, #4, #9, and #10 were opposite the irradiated sample, and chips #5, #6,

11, and #12 were below the bottom of the vial.

If the reading of the four chips opposite the sample are averaged, the result is

710 rad/min. Using an estimated 15 seconds contact time per sample, based on

re-enactments, and 140 samples handled per month, the total contact time is

estimated to be 35 minutes, and the dose would in this case be 24.8 rads. Using

the highest chip reading of 1115.4 rad/min, the total dose resulting from a contact

time of 35 minutes would be 39.0 rads, whereas using the smallest of the four

center chip readings gives a total dose of 14.7 rads. The results of the two finger

ring irradiations were reported by the processor before the end of this inspection

as 460 and 390 mrad/min. Using the exposure duration of 35 minutes, these

dose rates give a total dose for the month of 16.1 and 13.7 rad, respectively.

(3) Dose Calculations

As a second approach in attempting to assess the doses received by Worker A,

and to provide supporting data for the experimental measurements, both the

licensee and the NRC calculated the doses that would result from handling the

irradiated samples. The licensee attempted to use the computer codes VARSKIN

to calculate doses resulting from beta radiation, and MICROSHIELD to calculate

the doses arising from photons. However, neither code is capable of

representing the exposure geometry in this case with sufficient accuracy, and

-19-

both the licensee and NRC also used the Monte Carlo transport code MCNP to

supplement the VARSKIN calculations. MCNP can be used to model the

exposure geometry with any desired degree of accuracy, and can calculate doses

resulting from both photons and electrons. The dimensions used for the vials

were 7.5 cm length and 1.7 cm outer diameter for the larger outer vial, and 1.0 cm

length and 1.2 cm outer diameter for the inner vial. Each of the vials has a wall

thickness of 0.1 cm, and the vials are made of polyethylene. The calculations

were based on sample activities obtained by reviewing the records of the isotopic

gamma analyses and also by irradiating several samples during the inspection

under the same conditions used by Worker A. The isotopic composition used in

the calculations is shown in Table 4 below.

Table 4

Radionuclide Activity, µCi

Ag-108 90.0

Al-28 2.48

Cl-38 0.19

I-128 15.9

Na-24 0.54

The silver and iodine activities arise from the silver iodide contained in the

irradiated samples, and the aluminum, sodium, and chlorine most likely arise from

irradiation of trace constituents in the vial material.

The dose arising from photon irradiation was calculated by NRC to be about

0.03 rem for the badging period, and is therefore a negligible contributor to the

total SDE. The dose arising from beta radiation was estimated using MCNP to be

about 21 rads for a badging period of one month, using a total exposure duration

of 35 minutes. The licensees result from their MCNP calculations were 12.3 rads

without surgical gloves and 5.0 rads with the gloves. NRC also used VARSKIN to

calculate the beta dose. Although this code cannot accurately model the actual

exposure geometry, an approximation to that geometry was used, and the dose

calculated for the monitoring period of one month was 22 rads. The licensees

estimate using VARSKIN was 17.5 rads.

(4) Summary of Measurement and Calculation Results

Table 5 below summarizes the results of the TLD and ring badge measurements

and the calculations performed by NRC and the licensee. All the doses shown

are based on estimating the dose rate per minute and multiplying by an exposure

duration of 35 minutes to obtain the dose for the month.

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-21-

Table 5

Type of Dose Estimate Dose During the Month, rad

Mean of TLDs chip readings 24.8

Maximum TLD chip reading 39.0

Minimum TLD chip reading 14.7

Finger ring reading 16.1

Finger ring reading 13.7

MCNP calculation with gloves (NRC) 21.0

MCNP calculation with gloves (licensee) 5.0

MCNP calculation w/o gloves (licensee) 12.3

VARSKIN calculation (NRC) 22.0

VARSKIN calculation (licensee) 17.5

The results shown in the table show reasonable agreement considering the

various methods of calculation and measurement used to obtain these estimates.

They span a range of about 5 - 40 rads if the high TLD chip reading is included,

but span a much narrower range of 14 - 25 rads if the high reading is excluded,

as well as the licensees MCNP calculation with gloves. It therefore appears that

much of the data support the conclusion that the dose to Worker A was of the

order of probably not more than 25 rad, assuming the exposure duration of 35

minutes per month is correct. This is a factor of about 3 lower than the dose of

75.8 rad reported for the January period, and still significantly lower, by a factor of

about1.5 for the February period. The dose rates on which the tabulated doses

are based are probably reliable, especially since the calculations and

measurements are in agreement. The exposure duration was obtained by

multiplying the estimated contact time per sample, namely 15 seconds, by the

number of samples handled during the month. The number of samples handled

is a matter of record, and the exposure duration per sample is based on timing

the re-enactments observed by the NRC inspector.

It is possible that during the actual handling of samples, Worker A took much

longer to perform the required sample handling than was demonstrated during the

re-enactments, especially if one makes the reasonable assumption that this

worker gained increasing skill in handling the samples during this period. The

SDE pattern reported by the processor, namely 75.8 and 37.5 rads, is consistent

with this possibility. The time available to handle a sample, however, is not

unlimited, but is constrained by the nature of the process of sample irradiation

-22-

and analysis. Most of the radioactive materials produced by sample irradiation

have half-lives of the order of a few minutes, and the sample must therefore be

quickly transferred from the pneumatic system to the counting detector before the

activity decays away, thereby precluding the possibility of accurate isotopic

analysis. Re-enactments and interviews with Worker A and others have shown

that the total time taken from removal of the sample from the reactor pneumatic

system to the start of counting on the gamma spectrometer is very close to one

minute. Of this, 5 seconds are used to remove the sample from the pneumatic

system, and 10 seconds to set up the counting system in preparation for

counting. This leaves a maximum of about 45 seconds to handle the sample. If

the assumption is made that all of this time is taken up in sample handling, the

doses for the month based on a 15-second handling time are increased by a

factor of three. For example, a dose of 25 rads for the month estimated on the

basis of the mean TLD chip results becomes a dose of 75 rad, which is the SDE

dose reported for January. Improved handling skills would lead to reduced

handling time, and therefore a reduced dose for the month of February.

It should be noted that the above is highly speculative, and requires making some

unlikely assumptions, such as that the worker took 45 seconds to handle each of

the 140 samples during January, and that during each of these, the workers

fingers were placed around the sample such that the dosimeter chip was always

opposite the irradiated sample. Although not impossible, these coupled

conditions are highly unlikely. A more convincing conclusion is that the dose

received for January was of the same order of magnitude as that received during

February, and that the dosimeter used during the January badging period read on

the high side, an occurrence that is not infrequent.

(5) Dose Assignment

NRCs 10 CFR Part 20 defines the SDE as the dose at a depth of 0.007 cm in

skin averaged over the 10 cm2 area of skin that receives the highest dose from

the source of exposure. NRC performed calculations using MCNP to determine

the ratio of the dose registered by the finger ring dosimeter to the dose averaged

over the highest exposed 10 cm2 area of the skin of the workers hand. The result

showed the ratio to be 2.9. This means that the doses registered by the

dosimeter should be divided by 2.9 to determine the dose to be used to show

compliance. If the reported SDE for January and February, namely 75.8 and

37.54 rads, respectively, are considered valid and used to show compliance, the

total reported dose for January and February would be 113.3 rads, and the dose

to be assigned to Worker A would be 39.1 rads for the period starting January 1st

through the end of February. If the dose estimated on the basis of measured and

calculated dose rates and a 15-second handling period per sample, namely about

25 rads, is used for each of the 2 months, the total dose would be 50 rads, and

the assigned total dose would be 17 rads. In either case, the assigned dose is

significantly lower than the regulatory dose limit on SDE, which is 50 rem for the

year.

-23-

c. Conclusions

The inspectors concluded that, by using dose averaging to determine the SDE as

prescribed by the regulations, the assigned dose for the individual involved in the

event would be lower than the annual dose limit to the extremities for the year.

7. Licensee Actions to Ensure Regulatory Requirements Are Met

a. Inspection Scope (IP 69001)

The inspectors reviewed selected aspects of the following to verify compliance with

10 CFR Parts 19 and 20:

Licensee records and E-mails

Licensee dose calculations and test data

Personnel dosimetry records for facility personnel for 2005 to date

NSC SOP Section VII, Procedure A-3, Reporting Requirements, Revision 2,

dated December 19, 1997

NSC SOP Section VII, Procedure A-6, ALARA, Revision 0, dated December 12,

2002

NSC SOP Section VII, Procedure C-10, Radioactive Materials Handling,

Revision 2, dated December 19, 1997

NSC Form 844, Radiation Work Permit, Number (No.) 005, Revision (Rev.)

No. 05-0, dated November 15, 2005

Texas A&M University, Nuclear Science Center, Pneumatic System Training

Module, Rev. dated January 10, 2001

Texas A&M University, Nuclear Science Center, Radiation Worker Training

Module, no revision date

b. Observations and Findings

As noted above, once the licensee was aware of the dosimetry results for January,

Worker A was restricted from handling any radioactive samples and a review of the

situation was initiated. After consideration of the sample handling process and other

factors involved, the licensee concluded that this was an anomalous reading and a

dose estimate, based on past extremity doses, was prepared. Worker A was then

allowed to resume restricted or limited duty. Worker A did some tasks around the

facility but did not process any additional NAA sample vials because all the samples

for the period had already been processed.

On March 15, 2006, the licensee received the results from the dosimetry processor

which indicated that Worker A had received a dose to the extremities of 37.54 rem

during February. The Facility Director and RSO reviewed the results and the NRC

was notified immediately. It was reiterated that Worker A was only to be involved in

limited duty which did not involve dose to the extremities. As noted above, the

licensee then conducted re-enactments of the sample handling process, completed

careful measurements of the dose rates of the irradiated sample vials, and initiated

dose calculations using the dose measurements and various computer programs and

models including VARSKIN and MCNP. All NSC staff members were made aware of

-24-

the event and the fact that Worker A was not allowed to perform work involving

radioactive material that would result in a dose to the extremities. Worker A was also

sent for a medical examination on Thursday, March 30. The doctor found no

problems and no abnormalities. A follow-up exam was scheduled for April 27, 2006.

c. Conclusions

The inspectors determined Worker A had been restricted from working with or

handling radioactive material that would result in any additional dose to the

extremities.

8. Timely Reporting in the Future

a. Inspection Scope (IP 69001)

The inspectors reviewed selected aspects of the following to verify compliance with

10 CFR Parts 19 and 20:

NSC SOP Section VII, Procedure A-3, Reporting Requirements, Revision 2,

dated December 19, 1997

NSC SOP Section VII, Procedure A-6, ALARA, Revision 0, dated December 12,

2002

NSC SOP Section VII, Procedure C-10, Radioactive Materials Handling,

Revision 2, dated December 19, 1997

NSC Form 844, Radiation Work Permit, Number (No.) 005, Revision (Rev.)

No. 05-0, dated November 15, 2005

Texas A&M University, Nuclear Science Center, Pneumatic System Training

Module, Rev. dated January 10, 2001

Texas A&M University, Nuclear Science Center, Radiation Worker Training

Module, no revision date

b. Observations and Findings

As noted above, on February 24, 2006, the licensee received the results from the

dosimetry processor which indicated that Worker A had received a dose to the

extremities of 75.8 rem. Following receipt of this report, the Facility Director and the

Radiation Safety Officer informed the person of the extremity dose and prohibited the

individual from any duties that would add to his extremity dose. They subsequently

initiated an investigation. Worker A was questioned about his activities including:

1) where he typically stored his dosimetry when it was not in use, 2) whether or not he

had had any medical procedures involving radioactive materials, 3) whether he had

handled any radioactive material which was unknown to the NSC staff, or 4) whether

he was aware of any thing that would cause a high extremity dose. The individual had

no recollection of anything that would result in a high exposure to the hands other than

the high volume of pneumatic samples that were being processed during January and

February. The employee had handled 140 silver samples in January 2006.

In reviewing the apparent overexposure, the licensee reviewed various circumstances:

1) The process had been ongoing for over a year and no one had ever received doses

-25-

that exceeded 1.58 rem while performing this task. 2) Even during January 2006,

another employee had handled 195 samples and had received only 0.18 rem extremity

exposure. 3) Nothing in the process had changed and the composition of the samples

had not changed. 4) The dosimetry vendor had, in the past, contacted the licensee to

notify them of a potential problem with high doses. This was not done in this case for

some reason. 5) The dosimetry vendor also had sent the licensee anomalous

readings in the past and the current potential overexposure of the employees hands

was determined to be such based on past experience with handling this type of

sample. Based on the above and the employees work duties and assignments, his

previous dose history, and the extremity dose to the hands that had been received by

another worker, who had handled samples in January, the licensee decided that a

calculated dose assessment was needed for the employee.

On March 15, 2006, the licensee received the results from the dosimetry processor

which indicated that Worker A had received a dose to the extremities of 37.54 rem

during February. The Facility Director and RSO reviewed the results and the NRC

was notified immediately and it was reiterated that Worker A was restricted from any

handling of radioactive material that would produce an extremity dose. As noted

above, the licensee then conducted re-enactments of the sample handling process,

completed careful measurements of the dose rates of the irradiated sample vials, and

initiated dose calculations using the dose measurements and various other computer

models. All NSC staff members were made aware of the event and the fact that

Worker A was not allowed to perform work involving radioactive material that would

result in a dose to the extremities.

As a result of the event and the subsequent investigation of the possible cause(s) of

the reported overexposure, licensee management and staff were forcefully reminded

of the requirements in the regulations and their own procedures for reporting such

events in a timely manner. The corrective action for this problem, as indicated by the

licensee, was simply to report any such instances in the future. The licensee

determined that it would be much more prudent to report such an event, even if there

are questions about the veracity of the data, than to not report it. Also, if the data

show that the report was made in error, the report could be retracted.

c. Conclusions

The inspectors determined that the licensee will report any such event in the future.

9. Exit Interview

The inspection scope and results were summarized on March 29, 2006, with licensee

representatives. The inspectors discussed the findings for each area reviewed. The

licensee acknowledged the findings presented and did not identify as proprietary any of the

material provided to or reviewed by the inspectors during the inspection.

PARTIAL LIST OF PERSONS CONTACTED

Licensee

T. Fisher Supervisor, Reactor Maintenance

T. Maldonado Deputy Director, Texas Engineering Experiment Station

B. Pack Health Physics Technician

D. Reece Director, Nuclear Science Center

J. Remlinger Manager, Reactor Operations

L. Vasudevan Radiation Safety Officer

INSPECTION PROCEDURE USED

IP 69001 Class II Research and Test Reactors

ITEMS OPENED, CLOSED, AND DISCUSSED

Opened

50-128/2006-203-01 IFI Follow-up on the issue of ensuring that sufficient guidance and

instruction on the proper handling of radioactive material was

included in procedures, RWPs, and in the training program

(Paragraph 3.b.).

50-128/2006-203-02 IFI Follow-up on the licensees review of their Event Notification

procedure (Paragraph 4.b.(1)).

50-128/2006-203-03 IFI Follow-up on the licensees corrective actions taken in response

to the exposure event (Paragraph 4.b.(3)).

50-128/2006-201-04 VIO Failure to make adequate surveys to fully establish the

radiological hazards that were present following the initial trial

runs of vials containing plastic disks and failure to conduct

surveys of the sample vials of irradiated material following the

first indication of a possible overexposure on February 24, 2006,

to determine the cause of the problem which lead to a failure to

acceptably train and monitor workers regarding the handling of

sample vials with their hands/fingers (Paragraph 5.b(2)).

Closed

None

LIST OF ACRONYMS USED

Ag Atomic symbol for silver

ALARA As low as reasonably achievable

Ar Atomic symbol for argon

CFR Code of Federal Regulations

cm2 centimeters squared

Co Atomic symbol for cobalt

DDE Deep dose equivalent

HP Health Physics

I Atomic symbol for iodine

IFI Inspector Follow-up Item

IP Inspection Procedure

FCi microcurie

mCi millicurie

MeV million electron volts

mrad milliRAD

mrem millirem

nCi nanocurie

NAA Neutron activation analysis

NIST National Institute of Standards and Technology

NSC Nuclear Science Center

NRC Nuclear Regulatory Commission

OSL Optically stimulated luminescent

RAD Radiation Absorbed Dose

RSO Radiation Safety Officer

RSB Reactor Safety Board

RWP Radiation Work Permit

SDE Shallow dose equivalent

Si Atomic symbol for silicon

SNM Special Nuclear Materials

SOP Standard Operating Procedure

Tc Atomic symbol for technetium

TLD Thermoluminescent dosimeter

TS Technical Specifications

TEES Texas Engineering Experiment Station

VIO Violation

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