ML20210K410
| ML20210K410 | |
| Person / Time | |
|---|---|
| Issue date: | 08/03/1999 |
| From: | Camper L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Haddock S ADVANCED MEDICAL SYSTEMS, INC. |
| References | |
| SSD, NUDOCS 9908060101 | |
| Download: ML20210K410 (2) | |
Text
i St:phin J. Haddock Advanc:d M: dical Systsms, Inc. August 3, 1999
, 121 North Eagle Strset i
Cleveland, OH 44041 i
Dear Mr. Haddock:
On February 25,1999, the Hospital Center at Orange, New Jersey, notified our Region i office of a failure of a Model C-9 teletherapy unit source drawer mechanism to return to its "off" position after its pre-set time of five seconds had elapsed. Neither the depression of the Emergency Stop on the control console, nor the opening of the treatment door, caused the source to moved into its shielded position as intended. The patient was removed and the therapy room locked until service personnel arrived. However, the patient was estimated to have received an additional dose of approximately 27 rads.
The entire source wheel mechanism was replaced on March 3,1999, as a follow-up action.
The service company engineers indicated that the jamming of the source drive mechanism may
! be attributed to a system design problem. The NRC is concerned that repeated cycling of the teletherapy unit and resulting thermal shock may be adversely affecting the integrity of the source wheel. The current corrective action thus far has been by replacing the source wheel.
In addition to this incident, the NRC is aware of at least five (5) similar cases concerning the Model C-9 with a stuck source wheel. Usually activation of the Emergency Stop button is sufficient to drive the source the fully shielded position. However, as seen in the latest incident, this does not always work.
This latest incident has prompted us to evaluate this issue to determine whether this is indicative of a generic problem with the device and whether it is necessary for the NRC to take action repaiding the use and/or registration of the teletherapy unit. Please provide us with copies of your analysis regarding the cause of failure of this device, generic implications, ar>d any corrective actinns necessary,in accordance with 10 CFR Part 21.21 requirements, r
Please provide your response within sixty (60) days of this letter. If you have any questions plcese contact Mr. Frederick Sturz, at (301) 415-7273.
Sincerely, l I 6f[
(orig. signed by)
Larry W. Camper Brsnch Chief Materials Safety and inspection Branch Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety 0 And Safeguards Distribution: Ticket #iMNS-7351 IMNS r/f ME01 DOCUMENT NAME: H:\ERIC\ GAP \ letter to AMS Ta receive a copy of this document, indicate in the box: "C* = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N" = No cc,py OFFICE MSIB E MSlp), fl n / . l l NAME ECompton /( FStD[z) dfV7 m (d' '
DATE 5/f5 /99 5/IW/99 y 'n ' C
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UNITED STATES NUCLEAR REGULATORY COMMISSION I 2 WASHINGTON, D.C. 2055M001 k!j8 August 3, 1999 Stephan J. Haddock Advanced Medical Systems, Inc.
121 North Eagle Street Cleveland, OH 44041
Dear Mr. Haddock:
On February 25,1999, the Hospital Center at Orange, New Jersey, notified our Region I office of a failure of a Model C-9 teletherapy unit source drawer mechanism to return to its "otf" position after its pre-set time of five seconds had elapsed. Neither the depression of the Emergency Stop on the control console, nor the opening of the treatment door, caused the source to moved into its shielded position as intended. The patient was removed and the therapy room locked until service personnel arrived. However, the patient was estimated to have received an additional dose of approximately 27 rads.
The entire source wheel mechanism was replaced on March 3,1999, as a follow-up action.
The service company engineers indicated that the jamming of the source drive mechanism may be attributed to a system design problem. The NRC is concerned that repeated cycling of the teletherapy unit and resulting thermal shock may be adversely affecting the integrity of the source wheel. The current corrective action thus far has been by replacing the source wheel. !
In addition to this incident, the NRC is aware of at least five (5) similar cases concerning the Model C-9 with a stuck source wheel. Usually activation of the Emergency Stop button is sufficient to drive the source the fully shielded position. However, as seen in the latest incident, this does not always work.
This latest incident has prompted us to evaluate this issue to determine whether this is indicative of a generic probism with the device and whether it is necessary for the NRC to take action regarding the use ano/or registration of the teletherapy unit. Please provide us with copies of your analysis regarding the cause of failure of this device, generic implications, and any corrective actions necessary, in accordance with 10 CFR Part 21.21 requirements.
Please provide your response within sixty (60) days of this letter. If you have any questions please contact Mr. Frederick Sturz, at (301) 415-7273.
Sincerely, W
~
Lar W Dra ch ief h. Camper T
Matericts Safety and Inspection Branch Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety And Safeguards