United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 86-23: Excessive Skin Exposures Due To Contamination With Hot Particles

                                                 SSINS No: 6835 
                                                 IN 86-23

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                     OFFICE OF INSPECTION AND ENFORCEMENT
                            WASHINGTON, DC 20555

                                 April 9, 1986

Information Notice No. NO 86-23: EXCESSIVE SKIN EXPOSURES DUE TO           
                                       CONTAMINATION WITH HOT PARTICLES

Addressees:

All nuclear power reactor facilities holding an operating license (OL) or
a  construction permit (CP)

Purpose:

This information notice is provided to alert recipients of a potentially 
significant problem pertaining to skin contamination incidents It is
expected  that recipients will review this information for applicability
to their  facilities and consider action, if appropriate, to preclude a
similar problem  occurring at their facilities However, suggestions
contained in this notice  do not constitute NRC requirements; therefore,
no specific action or written  response is required

Description of Circumstances:

Three reactor licensees recently have reported excessive skin exposures to 
individuals as a result of contamination from single hot particles of 
radioactive material (See Attachment 1 for a more detailed description of 
these events) Hot particles are small (in some cases microscopic)
particles  of radioactive material with a high specific activity

All three licensees have concluded that the hot particles in those 
contamination events most probably were transferred to the individual from 
"clean" protective clothing (which are intended to prevent skin 
contamination) Review of the events discussed in Attachment 1 indicates
the  following additional common considerations:

1 Plants with hot particle problems experience multiple contamination
events  Once hot particles are loose in the plant they are difficult to
detect and  control Plants with a potential for generating hot particles
(those with  stellite components or poor fuel performance) should consider
additional  contamination control measures such as providing temporary
containment for  "hot" jobs, where feasible The INPO Significant Event
Report (SER) 42-85,  "Personnel Skin Contaminations Due to Activated
Stellite Particles," includes  a discussion on minimizing the introduction
of stellite to a reactor system




                                                 IN 86-23
                                                 April 9, 1986
                                                 Page 2 of 2

2 It is believed that the insides of protective clothing are being 
contaminated in the laundry system Reliance on the laundry process
monitors  in the cleaning fluid path and/or bulk gamma surveys of "clean"
protective  clothing is ineffective for detecting hot particles Licensees
may want to  segregate highly contaminated clothing from potentially
contaminated clothing  and launder each group separately to reduce the
chance of transferring hot  particles

3 In all the reported events, a need for more vigilance in personnel 
contamination control (self-frisking, protective clothing removal
procedures,  etc) is evident

A hot particle on the skin produces a very steep dose gradient with the
dose  dropping off rapidly as distance from the particle increases The
NCR dose  limit recommendations in NBS Handbook 59 (which provide the
basis for the  current NRC regulations) assumes that the critical area of
the skin is 10  cm**2 and that the radiosensitive basal layer of cells is
at a depth of  7mg/cm**2 below the surface For purposes of showing
compliance with 10 CFR  20101(a), calculating a skin dose averaged over
10 cm**2 at a depth of 7  mg/cm**2 is appropriate

No specific action or written response is required by this information
notice  If you have any questions about this matter, please contact the
Regional  Administrator of the appropriate regional office or this office

                                                                                                                            Edward L Jordan, Director
                                                                                                                            Division of Emergency Preparedness 
                                                                                                                              and Engineering Response
                                                                                                                            Office of Inspection and Enforcement

Technical Contacts: Roger L Pedersen, IE
                    (301) 492-9425

                    James E Wigginton, IE
                    (301) 492-4967

Attachments:
1 Description of Events
2 List of Recently Issued IE Information Notices




                                                 Attachment 1
                                                 IN 86-23
                                                 April 9, 1986             
                                     Page 1 of 3

                             DESCRIPTION Of EVENTS

McGuire:                  

On June 5, 1985, a contractor employee supporting the plugging operation
of a  steam generator at Duke Power Company's McGuire Station discovered a
small  area of skin contamination under the arm The contamination was
detected by a  contamination portal monitor when the individual exited the
controlled area  after removal of three sets of protective clothing
Further detailed surveys  of the contaminated skin area showed the
following results: 05 mR/hr gamma,  58 mrad/hr beta, and greater than
50,000 cpm with a pancake G-M detector The  contamination was
successfully removed using adhesive tape Further evaluation  showed that
the contamination was a single particle 40 microns in diameter  with an
activity of 12 microcuries (uCi) of Co-60 Calculation of the  absorbed
dose to l cm**2 of skin resulted in a skin dose of 106 rad This 
exceeded the maximum allowable dose of 75 rem in a quarter [10 CFR 
20101(a)]

Prior to the June event, a number of similar contamination incidents with
hot  particles of cobalt-60 had occurred but with lesser dose
consequences The   licensee's investigation led to the preliminary
conclusion that the cobalt-60  particles were transferred to the
individual from the "clean" protective clothing The licensee has
identified other Co-60 particles in the plant  laundry area The licensee
thus far believes the source of contamination to be  stellite valve seats
with high cobalt content in the primary coolant system  Small particles
of stellite may have been dislodged and transported to the  core, where
they would have been activated to Co-60 Subsequently, these particles
became trapped in protective clothing during maintenance activities  and
were not removed during normal laundering

The licensee subsequently initiated the following protective measures:

1 Disposal of all cotton protective clothing in use at the time of the
event;

2 Increased surveillance of protective clothing after laundering
(including  comprehensive surveys of both the inside and outside of
laundered protective  clothing using pancake probe G-M meters);

3 Increased vigilance in self-frisking procedures when exiting
contaminated  area and when traversing between frisking locations within
contamination  control zones; and

4 Further evaluations to determine where stellite valve seats are used
and  where they could possibly be eliminated

San Onofre:

On October 30, 1985, a firewatch employee found contamination while
"frisking  out" of the radwaste building (RWB) Investigation showed the
contaminant to  be a small speck of material attached to the outside back
of the individual's





                                                 Attachment 1 
                                                 IN 86-23
                                                 April 9, 1986
                                                 Page 2 of 3

modesty garment worn under protective clothing Frisker readings near the 
particle were in excess of 50,000 cpm beta-gamma An alpha count with a
SAC-4  survey instrument yielded 2,000 cpm Gamma spectrometric analysis
showed about  4 uci of material made up of Nb-95, Zr-95, Ru-103, Ru-106,
Ba-140, La-140,  Ce-141 and Ce-144 This composition suggests that the hot
particle is a tiny  fragment of fuel rather than the normal mix of
activation and fission products  which originate within the reactor
coolant system Careful frisking by  personnel at the RWB exit point
turned up a few more hot particles on modesty  garments and shoes
Extensive surveys pointed to the fuel reconstitution  equipment and work
area in the Unit 3 FHB as the most significant sources of  hot particles
Unit 3 has experienced significant fuel integrity problems  Recently San
Onofre performed fuel reconstitution in the spent fuel pool by  replacing
defective fuel pins in the affected fuel assemblies

On November 19, two additional instances of personnel contamination with
hot  particles were detected On November 21, a similar personnel
contamination was  detected Additionally, two more hot particles were
found in the FHB Work was  halted and the FHB was isolated Access to the
FHB is presently limited to  required operator surveillances with constant
HP coverage The licensee  determined that these skin contaminations
resulted from hot particles  transferred from "clean" protective clothing
Checks of protective clothing on  the ready-to-issue shelves revealed two
cases where protective clothing (which  met the "return to normal service"
criteria of less than 5,000 cpm/probe area)  were found, upon very slow
and careful frisking (15 minutes), to have hot  particles with activities
that exceeded this value Accordingly, a program is  being implemented to
withdraw all protective clothing presently in use for  thorough survey
under more restrictive criteria The clothing will be replaced  with
protective clothing that has been out of service since Unit 3 fuel 
reconstitution was initiated or with one-time-use disposal garments

A preliminary assessment of the dose received by the two individuals
involved  in the November 19 events indicates 13 rem to the skin of the
whole body and  7 rem to the skin of an extremity These are below the
dose limits set in  10 CFR 20101(a) However, these dose calculations are
currently under review  by the NRC

Other actions taken by the licensee include:

1 An extensive, special survey program (of workplace and protective
clothing)  is being maintained to assure the prompt detection and removal
of additional  hot particles

2 Full face respirators are required in FHB during work involving the
removal  of reconstitution tools

3 A special instruction was given to station personnel stressing the 
importance of good frisking practices, use of protective clothing, 
contamination control, and other H P practices




                                                 Attachment 1 
                                                 IN 86-23
                                                 April 9, 1986 
                                                 Page 3 of 3

Dresden:

On December 11, 1985, a hot particle was found near the abdomen area on
the  outside of an individual's undershirt The contamination was
initially found  by a portal monitor On analysis, the hot particle was
determined to contain  110 nanocuries (nCi) of Co-60 The licensee
concluded that the particle was  most likely transferred from protective
clothing to this undershirt Based on  the individual's work activities an
exposure time of 7 hours was estimated  resulting in a skin dose of less
than 1 rem

On January 4, 1986, a hot particle (44 nCi C0-60 and 1 nCi Cs-137) was
found  on a contract worker's abdomen while passing through a whole body
frisker The  licensee performed instrument response checks on the whole
body friskers,  postal monitors, and laundry monitors using the collected
hot particle The  licensee concluded that the particle was transferred
from protective clothing  to the worker's skin During interviews the
worker admitted that he routinely  omitted frisking after removing his
protective clothing at step-off pads With  the particle replaced near its
original position the licensee had the worker  pass through whole body
friskers several times; an alarm was received about 50  percent of the
time The licensee estimated the maximum probable time of  exposure to be
16 hours, resulting in a calculated skin dose of less than 5  rems

Actions taken by the licensee to prevent reoccurrence include:

1 Initiating a more aggressive laundry monitoring program; and

2 Emphasizing to contractors the need for worker compliance with
radiological  controls



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