Information Notice 1997-36, Unplanned Intakes by Worker of Transuranic Airborne Radioactive Materials and External Exposure Due to Inadequate Control of Work

Unplanned Intakes by Worker of Transuranic Airborne Radioactive Materials and External Exposure Due to Inadequate Control of Work
	ML031050563
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	06/20/1997
From:	Slosson M; Office of Nuclear Reactor Regulation
To:	;
References
	IN-97-036, NUDOCS 9706170322
	Download: ML031050563 (10)
	v • d • e

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 June 20, 1997 NRC INFORMATION NOTICE 97-36: UNPLANNED INTAKES BY WORKER OF

TRANSURANIC AIRBORNE RADIOACTIVE

MATERIALS AND EXTERNAL EXPOSURE DUE TO

INADEQUATE CONTROL OF WORK

Addressees

All holders of operating licenses and construction permits. All licensees of nuclear power

reactors in the decommissioning stage and fuel cycle licensees.

Purpose

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

licensees to inadequate radiological work controls in highly contaminated areas. These

inadequate controls created a substantial potential for personnel radiation exposures in

excess of NRC limits and resulted in unplanned intakes by workers of airborne radioactive

materials, including transuranics (alpha emitters). It is expected that recipients will review the

information in this notice for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in this information

notice are not NRC requirements; therefore, no specific action or written response is

required.

Description of Circumstances

On November 2, 1996, the Haddam Neck plant was in a refueling and maintenance outage.

Before flooding the reactor cavity, the fuel transfer canal (FTC), the fuel transfer cart and

tracks, and the upender needed to be inspected and debris removed to ensure cleanliness.

In preparation for the inspection and entry to the FTC, two workers (a maintenance

supervisor and a reactor vendor representative) met with health physics (HP) supervisors and

HP technicians (HPTs) to discuss the entry. As this work was not on the master outage

schedule, this was the first notice to HPTs of the work. The governing work procedure

provided no work scope detail. The meeting was not effective; there was no common

understanding between the workers and the HPTs as to what work was to be done and the

radiological conditions in the work area. The HPTs mistakenly believed that the workers

would principally walk along the FTC tracks but could periodically leave the tracks to pick up

debris (e.g., tie wraps) that had fallen down from the charging floor. The HPTs did not know

that the workers would collect, by hand, paint chips, metal rust, and dried, dirtlike materials

from the floors and walls.

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IN 97-36 June 20, 1997 Just before the entry, the HPTs briefed the workers on the radiological conditions. Since the

FTC was decontaminated in August 1996, the workers were led to believe that the canal was

generally "clean." The licensee had not performed any prework contamination or radiation

surveys to support the job. Surveys later found that the FTC contained removable

contamination of up to 800 microgrey/h [80 milliradlhr] (beta/gamma) and 500 Bq [30,000

disintegrations per minute) per 100 square centimeters (dpml100 cm2) alpha contamination.

In addition, a local hot spot on the canal floor, readily accessible to the workers, exhibited

external radiation levels of 250 mSv/h [about 25 R/h] on contact and 80 mSvlh [about 8 R/h]

at waist level. The prework briefing of the workers was inadequate, and the workers were

not informed of the actual radiological conditions. Additionally, the work was allowed to

commence under an invalid (because it did not allow FTC entry) radiation work permit

(RWP), rather than a specific RWP for the FTC. As a result, no comprehensive, prework

radiation or contamination surveys were performed. The decision not to issue respiratory

protection was based on previous air sample results (after the August 1996 reactor cavity

decontamination to support worker tours of the area). However, this dated sampling was not

representative of the extensive debris cleanup activity on November 2, 1996.

While in the FTC, the workers scraped up debris from the FTC and placed it in a plastic bag.

Unknown to the workers, this activity generated significant airborne radioactive materials and

created a high-intensity external radiation source.

After completion of the work, one workers dosimeter alarmed upon exiting the reactor cavity.

The plastic bag of debris was surveyed for the first time and read 200 mSv/h [about 20 R/h]

on contact (it was placed in shielded storage). A later survey of the bag indicated 600 mSv/h

[about 60 R/h] on contact and about 40 mSv/h [about 4 R/h] about 30 centimeters away. The

workers wore no additional dosimetry other than their electronic alarming and standard chest

thermoluminescence dosimeters (TLDs). The workers found significant contamination, while

whole-body frisking. Nasal smears of the workers indicated 3333 Bq 1200,000 dpmJ

(beta/gamma) shortly after exiting the cavity. Subsequent to the event, the licensee

determined (by analysis and reconstruction) the workers' deep-dose equivalent (DDE), the

shallow-dose equivalent (SDE, whole body), the maximum doses to the extremities, and the

lens dose equivalent (LDE) from the collection and handling of the debris. None of the

worker's external doses were in excess of the limits, with the maximum assigned doses

(mSv) of 4.73 [473 mrem], DDE; 4.73 [473 millirem], SDE; 11.6 [1164 mreml, extremity; and

3.97 [397 mrem], LDE.

With the workers out of the cavity, an HPT checked the FTC air sample using a hand-held

frisker and found that the sample exhibited an elevated count rate, indicating the presence of

potential airborne radioactive material. This air sample later indicated about 0.8 derived air

concentration (DAC) beta and 24 DAC alpha. The general area air sample was not

representative (not in the breathing zone of the workers) of the concentrations encountered

by the workers during the debris cleanup.

A backup air sample of the reactor cavity was started, well away (non-representative) from

the FTC. The sample was also checked in the field with a different (but defective) hand-held

IN 97-36 June 20, 1997 frisker, which erroneously indicated no airborne radioactive materials were present. Other

HPTs in the area were then notified (misinformed) that the air within the reactor cavity was

clean. The inspector later found that the licensee had failed to establish and implement an

effective program to adequately check for proper operability of the frisker in containment.

On the basis of the erroneous negative air sample result, HPTs authorized two other workers

to enter the reactor cavity and clean the reactor vessel stud holes. These workers

unknowingly spent about 15 minutes in an area with elevated airborne radioactive material

levels and subsequently exited the reactor cavity. Their subsequent whole-body counts

showed no significant intakes.

The licensee's subsequent counting of the backup air sample prompted identification of the

inoperable frisker and subsequent evacuation of the reactor cavity and initiation of an

investigation. The backup air sample was found to indicate airborne radioactivity

concentrations of 3.5 DAC beta and 108 DAC alpha. The air sample collected near where

the two workers were working on the reactor vessel studs was later found to indicate

1.5 DAC beta and 53 DAC alpha. In spite of these air sample results (high alpha DACs),

their non-representative nature (not near the FTC), and the stay-times of the workers and

their work practices in the FTC (handling contaminated debris), the licensee did not recognize

the potential for excessive personnel exposure until about a week after the event.

Discussion

In the Haddam Neck event, inadequate radiological evaluations and controls led to unplanned

internal exposures with a substantial potential for worker overexposures. Of more concern

was that until identified by an NRC inspector five days after the event, the licensee failed to

recognize the potential for significant internal doses from transuranic radionuclides known to

be present in the FTC. The presence of these alpha-emitting nuclides was evident from

loose surface contamination sampling (smears) and air samples. This failure led to untimely

initiation of in-vitro bioassays (fecal sampling) for the transuranic material intake to assess

personnel exposures. While the whole-body counting (WBC) indicated a relatively low

intake/dose from cobalt-60, the licensee failed to use the high alpha-to-beta gamma ratios

(from the air and smear samples) to identify the potential for significant internal doses to

workers from the transuranic component. When the NRC inspector noted the WBC result for

the gamma emitters (power plant WBC's do not detect alpha radiation) and took into account

the relative workplace abundance and typical DAC alpha-to-beta gamma nuclide ratios, he

informed the licensee of the transuranic concern.

The licensee then initiated fecal sampling to account for doses from all nuclides (including

alpha emitters). The licensee contracted outside consultants to perform a detailed analysis of

the event and calculate the workers' internal dose. On the basis of this effort, the licensee

reported a maximum 9.13 mSv [913 mrem] committed effective dose equivalent (CEDE) and

58.7 mSv 15873 mrem] total organ dose equivalent (TODE) to the bone surface. None of the

reported doses are In excess of regulatory limits. However, the NRC staff is still reviewing

the licensee's methods, assumptions and models for the internal dose assessment.

IN 97-36 June 20, 1997 For reactor facilities that have experienced fuel defects, experience has shown that long after

the defective fuel has been removed, significant alpha contamination may remain in generally

inaccessible locations, such as the FTC equipment drains and sumps, and other refueling

areas. Even minor disturbance of the contaminated surfaces can result in the release of

alpha-emitting radionuclides, whose DACs are orders of magnitude more restrictive and

limiting (at much lower concentrations) compared with the normal beta-emitting and gamma- emitting isotopes usually encountered in reactor plant environments (fission, corrosion, and

wear products). Additionally, alpha contamination may be incorporated into a

contamination/corrosion layer on the interior surfaces of system components that carry

primary fluids or steam. Surveys for loose surface contamination may not identify the fixed

alpha contamination, but abrasive work (e.g., grinding or welding) may result in alpha- emitting airborne radioactive materials. This latter characteristic may be particularly important

at reactor facilities undergoing decommissioning.

As a result of this event, the licensee performed root cause analyses. On the basis of these

analyses and the findings of an independent review team, the licensee has initiated certain

corrective actions, which include the following:

1. All work presenting a significant radiological challenge (within designated high-risk

areas) was suspended until a work approval program was instituted. This program

now requires review of all RWPs by the plant Radiation Protection Manager (RPM)

and the Work Services Director, and RWP approval by the RPM or the Radiological

Protection Supervisor.

2. The work control program now includes an RWP procedure requiring clear

descriptions of authorized work and controls, improved procedures for high-risk

evolutions, and representative prework surveys.

3. The license stopped the use of in-field counting and checks for air samples as a basis

for reducing or relaxing radiological work controls.

4. All work in high alpha-intake risk areas requires the use of respirators until

representative air sampling justifies work without respiratory protection.

Events involving unplanned intakes of airborne radioactivity at nuclear power plants occur

generally during maintenance and refueling outages, are infrequent, and typically result in

intakes by workers of radioactive material that are well within the limits of 10 CFR Part 20.

However, as indicated in the event describe in this notice, the potential for significant

unplanned personnel exposures does exist at nuclear power plants (see related

correspondence).

Related Communications and Correspondence

The following related communications and correspondence are noted:

NRC Inspection Report No. 50-219/96-12, dated December 19, 1996.

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IN 97-36 June 20, 1997 * NRC Information Notice 90-47, "Unplanned Radiation Exposures to Personnel

Extremities Due to Improper Handling of Potential Highly Radioactive Sources," dated

July 27, 1990.

NRC Information Notice 92-75, "Unplanned Intakes of Airborne Radioactive Material

by Individuals at Nuclear Power Plants," dated November 12, 1992.

This information notice does not require any specific action or written response. If you have

any questions about the information in this notice, please contact one of the technical

contacts listed below.

Marylee M. Slosson, Acting Direct r

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Ronald L. Nimitz, RI

(610) 337-5267 E-mail: rln@nrc.gov

William J. Raymond, RI

(860) 267-2571 E-mail: wjr@nrc.gov

James E. Wigginton, NRR

301-415-1059 E-mail: jew2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

I/d P' r- t

Attachment

IN 97-36 June 20, 1997 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

97-35 Retrofit to Industrial 06/18/97 All industrial radiography

Nuclear Company (INC) licensees

IR100 Radiography Camera

to Correct Inconsistency

in 10 CFR Part 34 Compatibility

97-34 Deficiencies in Licensee 06/12/97 All holders of OLs or CPs

Submittals Regarding for test and research

Terminology for Radio- reactors

logical Emergency Action

Levels in Accordance

With the New Part 20

97-33 Unanticipated Effect 06/11/97 All holders of OLs or CPs

of Ventilation System for nuclear power reactors

on Tank Level Indica- tions and Engineering

Safety Features Actua- tion System Setpoint

95-36, Potential Problems 06/10/97 All holders of OLs or CPs

Supp. 1 with Post-Fire Emer- for nuclear power reactors

gency Lighting

97-32 Defective Worm Shaft 06/10/97 All holders of OLs or CPs

Clutch Gears in for nuclear power reactors

Limitorque Motor- Operated Valve

Actuators

97-31 Failures of Reactor 06/03/97 All holders of OLs or CPs

Coolant Pump Thermal for pressurized-water

Barriers and Check reactor plants

Valves in Foreign

Plants

OL = Operating License

CP = Construction Permit

IN 97-37 June 20, 1997 the fire to spread to that room and could have resulted in the loss of the A switchgear as

well.

The Pilgrim licensee enhanced the fire protection design in the turbine building by installing

containment curbs at the fire doors leading to the A essential switchgear room and the

stairway leading to the radwaste holding tanks, and modified the iso-phase bus duct by

installing an 8-inch diameter downcomer drain line on each of the three phases. Each drain

line is routed to drain into the oil leak retention pit, and will be equipped with a rupture disc

designed to open under 2 psig of static oil pressure in the drain line down-comer.

This information notice requires no specific action or written response. If you have any

questions about the Information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

original signed by S.H. Weiss for

Marylee M. Slosson, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Patrick Madden, NRR

301-415-2854 E-mail: pmm@nrc.gov

David Skeen, NRR

301-415-1174 E-mail: dls2nrc.gov

Attachment: List of Recently Issued NRC Information Notices

Tech Editor has reviewed and concurred on 5/19197 DOCUMENT

NAME: G:XDLSUN97-XX.PLG *SEE PREVIOUS CONCURRENCES

OFC TECH C:SPLB C:PECB D:(A)DRPM

CONTACT

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NAME DSkeen* LMarsh* AChaffee* MSloss

PMadden*__ _ _

DATE 06/02/97 05/27/97 06/13/97 //797 /

05/27/97

IN 97-XX

June XX, 1997 the fire to spread to that room and could have resulted In the loss of the A switchgear as

well.

The Pilgrim licensee enhanced the fire protection design In the turbine building by installing

containment curbs at the fire doors leading to the A essential switchgear room and the

stairway leading to the radwaste holding tanks, and modified the Iso-phase bus duct by

installing an 8-inch diameter downcomer drain line on each of the three phases. .Each drain

line is routed to drain into the oil leak retention pit, and will be equipped with a rupture disc

designed to open under 2 psig of static oil pressure in the drain line down-comer.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Marylee M. Slosson, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Patrick Madden, NRR

301-415-2854 E-mail: pmm@nrc.gov

David Skeen, NRR

301-415-1174 E-mail: dls@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:XDLSklN97-XX.PLG *SEE PREVIOUS CONCURRENCES

OFC TECH C:SPLB C:P, D:(A)DRPM

CONTACT

S_

NAME DSkeen* LMarsh*A ffe. MSlosson

PMadden*

DATE 06102197 05/27/97 A97 1/97

05127197 OAFFICIAL KRECOKR W TYj

0& bll-P-8

IN 97-XX

June XX, 1997 the fire to spread to that room and could have resulted in the loss of the A switchgear as