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RE : radiographer "overexposure"



I don't know about the QA problem but I am not sure about the "lesson

learned".  I think that the only secure position when moving with a

gammagraphy device like a Tech-Ops 660B is to LOCK the source PRIOR to any

movement. This will ensure that the source will mechanically be locked

inside shielding.  I keep the same safety procedures for my program here

when NDT is required. You can't go and move a 70-100 Ci Ir-192 source

without locking the source in place, securing the control cable is a bit

short for safety.



Regards,



Stéphane Jean-François, Eng., CHP

Spécialiste en radioprotection/Health Physics specialist

Gestion des risques/Risk Management

Centre de recherche thérapeutique de Merck Frosst/Merck Frosst Center for

Therapeutic Research

514-428-8695

FAX: 514-428-8670

stephane_jeanfrancois@merck.com

www.merckfrosstlab.ca





-----Message d'origine-----

De : William V Lipton [mailto:liptonw@DTEENERGY.COM] 

Envoyé : Tuesday, July 29, 2003 7:38 AM

À : radsafe@list.vanderbilt.edu

Objet : radiographer "overexposure"





Please review the attached, NRC event report, based on an Agreement

State report.  Although the radiographers' actions seem reasonable

(lesson learned - Secure the control cable to the lift.), I have 2

concerns:  (1) the film badge processor reported a dose of  "1,423,000

mrem".  For an acute exposure of that magnitude, mrem is not a valid

unit.  The dose should have been reported in mrads gamma.  (2) Although,

based on a lack of symptoms, the reported dose is not valid, it seems

that the investigators wrote off the overexposure too easily.  They

should have determined whether the processor has a serious QA problem.

Have they looked at the film?  My guess is that, if they did, they'd see

that there's a pinhole light leak.  In any event, the processor's QA

program should be reviewed.



The opinions expressed are strictly mine.

It's not about dose, it's about trust.

Curies forever.



Bill Lipton

liptonw@dteenergy.com



  EVENT TEXT

+---------------------------------------------------------------------------

---+



| WA AGREEMENT STATE REPORT ON POSSIBLE OVEREXPOSURE

INCIDENT                  |

|

|

|

|

| "Licensee: PM TESTING

LABORATORY                                             |

| "Licensee number:

WN-11R047-1                                                |

| "Type of licensee: Industrial

Radiography                                    |

|

|



| "Date of event: March 5,

2003                                                |

| "Location of event: Port of Tacoma, WA. German cargo ship  'Big

Lift'        |

|

|

| "ABSTRACT: (as reported by licensee's representative) A radiographer

and     |

| Assistant Radiographer were performing radiography at the Port of

Tacoma, on |

| a German cargo ship  'Big Lift'  on March 5, 2003, at approximately 10

PM    |

| [PST]. The work required the radiographers to use a cherry-picker

type       |

| lifting vehicle to access the work area since the area was about 100

feet    |

| above deck level. The Radiographer and Assistant were both in the

lift       |

| bucket, 2 feet apart, at the time of the incident. The

industrial            |

| radiographic device (Amersham Corporation Model 660B,

containing             |

| approximately 70 curies of iridium 192) with connected guide

tube,           |

| collimator and control cables had been lifted into position and

secured in   |

| the area of the intended exposure. The exposure device had been made

ready   |

| for the exposure. The operation required the Radiographer and

Assistant to   |

| move the lift as far from the exposure area as possible while

extending the  |

| control

cable.                                                               |

|

|

| "As the lift was being positioned away from the work area it swayed,

this    |

| startled the radiographer who dropped the control cable. The sway

also       |

| caused the lift's engine to stall. The action of dropping the control

cable  |

| to the extent of its length and resulting sudden stop at the end of

the drop |

| caused the source to become unshielded. Their survey meter immediately

went  |

| off scale on the highest scale and their alarm-rate meters were

alarming.    |

|

|

| "It took the radiographers, by their estimate, about 30 seconds to

restart   |

| the [lift] vehicle, move the bucket so they could recapture the

control      |

| cable and secure the source. When they were able to check their

pocket       |

| ion-chambers, they found them off scale. Work was stopped for the day

and    |

| both film badges were sent for

processing.                                   |

|

|

| "Results from film badge processing and analysis indicated the

Radiographer  |

| received a whole body exposure of 1600 millirem. This coincided with

the     |

| calculations made by the Radiographer after the incident. The film

badge for |

| the Assistant indicated an exposure of 1,423,000 millirem. When the

badge    |

| processor was contacted and asked to reanalyze the film they stated

they got |

| the same

exposure.                                                           |

|

|

| "Since both radiographers were within 2 feet of each other in the

lift       |

| basket and calculations confirmed that the Radiographer's exposure was

1600  |

| milliRem, it appears the exposure to the Assistant was

incorrectly           |

| determined. In addition, the Assistant is not exhibiting any signs of

an     |

| excessive exposure. The company is submitting a report of the

incident. The  |

| Division is performing an investigation. Media, at present, are

not          |

|

involved.

|

|

|

| "What is the notification or reporting criteria involved? WAC

246-221-260,   |

| Reports of overexposures and excessive levels and

concentrations.            |

|

|

| "Activity and Isotope(s) involved? 70 curies of Iridium

192.                 |

|

|

| "Overexposure? Until the investigation indicates otherwise, the

process      |

| report of the Assistant's film badge indicates a whole body exposure

of      |

| about 1,423,000 milliRem. The over exposure is apparently not real

since     |

| calculations using exposure time, distance and source activity and a

second  |

| film badge, worn by another individual closely associated with the

first all |

| indicate exposure is unusual but much lower. Staff will

investigate."        |

|

|

| * * * UPDATE 1326 EDT on 7/25/03 FROM A. SCROGGS VIA EMAIL TO THE OPS

CENTER |

| * *

*

|

|

|

| The following is a portion of an email received from the Dept. of

Health,    |

| Rad Materials

Section:                                                       |

|

|

| "The initial report indicated that an Assistant Radiographer appeared

to     |

| have received an overexposure.  The Department's investigation

determined    |

| this not to be

true.                                                         |

|

|

| "As a result of the department's investigation of the event and review

of    |

| the radiography company's assumptions and calculations, the

Assistant's      |

| exposure was determined to be 1600 millirem.  Although this is a

significant |

| and unusual exposure, given the circumstances of the event, the

department   |

| considers that any health effects would be

minimal.                          |

|

|

| "The event is considered to be

closed."                                      |

|

|

| Notified R4DO (Pruett) and NMSS

(Greeves).                                   |

+---------------------------------------------------------------------------

---+











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