Information Notice 2007-35, Varian Medical Systems Varisource HDR Events: Iridium-192 Source Pulled from Shielded Position
| ML072760661 | |
| Person / Time | |
|---|---|
| Issue date: | 10/17/2007 |
| From: | Schlueter J NRC/FSME/DMSSA |
| To: | |
| Herrera T, FSME/DMSSA, 301-415-7138 | |
| References | |
| IN-07-035 | |
| Download: ML072760661 (7) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF FEDERAL AND STATE MATERIALS
AND ENVIRONMENTAL MANAGEMENT PROGRAMS
WASHINGTON, D.C. 20555
October 17, 2007
NRC INFORMATION NOTICE 2007-35:
VARIAN MEDICAL SYSTEMS
VARISOURCE HDR EVENTS:
IRIDIUM-192 SOURCE PULLED FROM
SHIELDED POSITION
ADDRESSEES
All U.S. Nuclear Regulatory Commission (NRC) medical use licensees and NRC Master
Materials Licensees authorized to possess or use a Varian Medical Systems VariSource
High Dose Rate Remote Afterloader (VariSource HDR). All Agreement State Radiation
Control Program Directors and State Liaison Officers.
PURPOSE
The NRC is issuing this information notice (IN) to alert addressees to recently reported
events where the use of the emergency manual retract hand wheel on the VariSource
HDR has caused the active iridium-192 (Ir-192) source to be pulled out of the shielded
position. It is expected that recipients will review the information for applicability to their
facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this IN are not new NRC requirements; therefore, no specific
action or written response is required.
NRC is providing this IN to the Agreement States for their information, and for
distribution to their medical use licensees, as appropriate.
DESCRIPTION OF CIRCUMSTANCES
NRC has received four event reports in the last three years, two of them recently, involving the VariSource HDR Ir-192 source having been pulled out of the shielded
position, while using the manual retract hand wheel. The four events occurred in a
range of different situations, two occurred during clinical use of the afterloader, one
occurred during routine QA/QC checks, and the other occurred during student training.
In one of the four incidents reported, while the patient treatment was being planned, the
wire containing the dummy (non-radioactive) source did not return during pre-treatment
preparations. The manual retract hand wheel, which is intended only for the wire
containing the radioactive source and not for the dummy source, was used by the
physicist in an attempt to retract the dummy source. However, when the physicist turned
the hand wheel, the active source was pulled out of the tungsten safe. Two of the
events occurred when the operator of the VariSource HDR attempted to retract a stuck
dummy source with the manual retract hand wheel. Their attempt to manually retract the
dummy source caused the active Ir-192 source to be pulled out of the tungsten safe.
The remaining event occurred during a training exercise when an instructor asked four
students to simulate using the manual retract hand wheel, however, two of the students
actually turned the hand wheel and caused the active Ir-192 source to be pulled out of
the tungsten safe.
DISCUSSION
Three of the four events occurred because the operators used the manual retract hand
wheel in an attempt to retract the dummy source back into the VariSource HDR unit.
The fourth event occurred during a training session. The warning label on the manual
retract hand wheel reads Warning - Active Source Wire Emergency Retract only. Turn
the hand wheel for a maximum of 12 turns or until the radiation alarm ceases. Contact
Varian Service. Varian filed an initial notification dated September 17, 2007, with NRC
in accordance with 10 CFR 21.21, following the latest event on July 15, 2007. The
report delineated the event and the design characteristics of the VariSource HDR unit for
safe use.
While potential long-term solutions are being considered, licensees should be aware that
consequences of the active Ir-192 source being pulled out of the tungsten safe would
result in the following:
1. The source would be contained within the unit, but would be unshielded and
could not be returned to the shielded position.
2. The exposure rate for a 10 Curie Ir-192 source that has been pulled out of the
tungsten safe would have an exposure rate of 18 R/hr at 50 cm.
3. A recovery operation would be needed to retrieve and secure the source.
4. Treatments could not resume until a new source wire is installed.
This IN serves as a reminder that the manual retract hand wheel on the VariSource HDR
units is intended only for the wire containing the Ir-192 source. The manual retract hand
wheel does not retract the dummy source. In the event that the dummy source is stuck
in the out position, the console displays Error Code 88. The operators should consult
the operators manual provided by Varian Medical Systems and contact Varian Service.
Licensees should also read Varians Customer Technical Bulletin (CTB) VS-366A,
Clarification on the Use of the Emergency Retract Hand Wheel to Prevent Accidental
Exposure. The CTB is available at the following website:
www.varian.com/shared/oncy/pdf/CTB-VS-366a.pdf
In addition, in the event of an emergency where an operator needs to use the manual
retract hand wheel to return the active Ir-192 source to the shielded position, operators
should be aware that the number of turns necessary to return the source to the tungsten
safe may vary. The number of turns may vary depending on how extended the source is
initially and on any potential for slippage between the pinch rollers and the source wire, especially with a freshly lubricated source wire. The VariSource HDR units are designed
IN 2007- 35 in such a manner that the operator only knows if the source has returned to the shielded
position when the audible radiation alarms and red light indicator turn off. Operators
should be aware that if the manual retract hand wheel is turned too many times the
active Ir-192 source can be pulled out of the tungsten safe. The unit was not designed
to have a positive lock to prevent the source from being pulled out of the tungsten safe
or to indicate that the source is in the shielded position.
CONTACT
This IN requires no specific action of written response. If you have any questions about
this IN, please contact one of the individuals listed below or the appropriate regional
office.
/RA/
Janet R. Schlueter, Director
Division of Materials Safety
and State Agreements
Office of Federal and State Materials
and Environmental Management Programs
Technical Contact:
(301) 415-7138
E-mail: txh1@nrc.gov
Medical Issues Contact:
(301) 415-0223
Email: cmf@nrc.gov
Enclosure: List of Recently Issued FSME/NMSS Generic Communications
Note: NRC generic communications may be found on the NRC public Website, http://www.nrc.gov, under Electronic Reading Room/Document Collections.
IN 2007- 35 in such a manner that the operator only knows if the source has returned to the shielded
position when the audible radiation alarms and red light indicator turn off. Operators
should be aware that if the manual retract hand wheel is turned too many times the
active Ir-192 source can be pulled out of the tungsten safe. The unit was not designed
to have a positive lock to prevent the source from being pulled out of the tungsten safe
or to indicate that the source is in the shielded position.
CONTACT
This IN requires no specific action of written response. If you have any questions about
this IN, please contact one of the individuals listed below or the appropriate regional
office.
/RA/
Janet R. Schlueter, Director
Division of Materials Safety
and State Agreements
Office of Federal and State Materials
and Environmental Management Programs
Technical Contact:
(301) 415-7138
E-mail: txh1@nrc.gov
Medical Issues Contact:
(301) 415-0223
Email: cmf@nrc.gov
Enclosure: List of Recently Issued FSME/NMSS Generic Communications
Note: NRC generic communications may be found on the NRC public Website, http://www.nrc.gov, under Electronic Reading Room/Document Collections.
OFC
DMSSA/SSSB
DMSSA/SSSB
DMSSA/MSEA
DMSSA/SSSB
NAME
THerrera:tyh
JJankovich
SWastler for
CFlannery
CEinberg
DATE
10/02/07
10/02/07
10/04/07
10/09/07
OFC
DMSSA/MSEA
FSME/DMSSA
FSME/DMSSA
NAME
AMcIntosh
RLewis
JSchlueter
DATE
10/09/07
10/17/07
10/17/07
OFFICIAL RECORD COPY Recently Issued FSME/NMSS Generic Communications
Date
GC No.
Subject
Addressees
02/02/07 IN-07-03 Reportable Medical Events Involving
Patients Receiving Dosages of
Sodium Iodide Iodine-131 less than
the Prescribed Dosage Because of
Capsules Remaining in Vials after
Administration
All U.S. Nuclear Regulatory Commission
medical use licensees and NRC Master
Materials Licensees. All Agreement State
Radiation Control Program Directors and
State Liaison Officers.
02/28/07 IN-07-08 Potential Vulnerabilities of Time- reliant Computer-based Systems
Due to Change in Daylight Saving
Time Dates
All U. S. Nuclear Regulatory Commission
licensees and all Agreement State
Radiation Control Program Directors and
State Liaison Officers.
03/13/07
Sirspheres Impurities
All U.S. Nuclear Regulatory Commission
(NRC) Medical Licensees and NRC Master
Materials Licensees. All Agreement State
Radiation Control Program Directors and
State Liaison Officers.
04/04/07 IN-07-13 Use of As-Found Conditions to
Evaluate Criticality-related Process
Upsets at Fuel Cycle Facilities
All licensees authorized to possess a
critical mass of special nuclear material.
05/02/07 IN-07-16 Common Violations of the Increased
Controls Requirements and Related
Guidance Documents
All licensees who are implementing the
U.S. Nuclear Regulatory Commission
(NRC) Order Imposing Increased Controls
(EA-05-090), issued November 14, 2005 and December 22, 2005.
05/21/07 IN-07-19 Fire Protection Equipment Recalls
and Counterfeit Notices
All holders of operating licenses for nuclear
power reactors and fuel cycle facilities;
except those licensees for reactors that
have permanently ceased operations and
who have certified that fuel has been
permanently removed from the reactor
vessel; and except those licensees for
decommissioned fuel cycle facilities.
06/11/07 IN-07-20
Use of Blank Ammunition
All power reactors, Category I fuel cycle
facilities, independent spent fuel storage
installations, conversion facility, and
gaseous diffusion plants. Date
GC No.
Subject
Addressees
07/19/07 IN-07-25 Suggestions from the Advisory
Committee on the Medical Use of
Isotopes For Consideration to
Improve Compliance With Sodium
Iodide I-131 Written Directive
Requirements in 10 CFR 35.40 and
Supervision Requirements in 10
CFR 35.27 All U.S. Nuclear Regulatory Commission
(NRC) medical-use licensees and NRC
Master Materials Licensees. All Agreement
State Radiation Control Program Directors
and State Liaison Officers.
08/08/07 IN-07-23 Inadvertent Discharge of Halon
1301Fire-suppression System from
Incorrect and/or Out-of-date
Procedures
All holders of operating licenses for nuclear
power reactors, except those who have
permanently ended operations and have
certified that fuel has been permanently
removed from the reactor vessel. All
holders of licenses for fuel cycle facilities.
08/13/07 IN-07-26 Combustibility of Epoxy Floor
Coatings at Commercial Nuclear
Power Plants
All holders of operating licenses for nuclear
power reactors and fuel cycle facilities
except licensees for reactors that have
permanently ceased operations and who
have certified that fuel has been
permanently removed from the reactor
vessel.
09/13/07 IN-07-30
Radiological Controls Create
Criticality Safety Accident Scenario
for Fissile Solution Container
Transport at Fuel Cycle Facility
All licensees authorized to possess a
critical mass of special nuclear material.
09/28/07 IN-07-33 Exposures To Members Of The
Public Caused By Inadequate
Controls Over Well Logging
Sources
All U.S. Nuclear Regulatory Commission
Well Logging Licensees. All Agreement
State Radiation Control Program Directors
and State Liaison Officers.
03/01/07 RIS-07-03 Ionizing Radiation Warning Symbol
All U.S. Nuclear Regulatory Commission
licensees and certificate holders. All
Radiation Control Program Directors and
State Liaison Officers
03/09/07 RIS-07-04 Personally Identifiable Information
Submitted to the U.S. Nuclear
Regulatory Commission
All holders of operating licenses for nuclear
power reactors and holders of and
applicants for certificates for reactor
designs. All licensees, certificate holders, applicants, and other entities subject to
regulation by the U.S. Nuclear Regulatory
Commission of the use of source, byproduct, and special nuclear material
03/20/07 RIS-07-05 Status and Plans for Implementation
of NRC Regulatory Authority for
Certain Naturally-occurring and
Accelerator-produced Radioactive
Material
All NRC materials licensees, Radiation
Control Program Directors, State Liaison
Officers, and NRCs Advisory Committee
on the Medical Uses of Isotopes
04/05/07 RIS-07-07 Clarification of Increased Controls
for Licensees That Possess
Collocated Radioactive Material
During Transportation Activities
All U.S. Nuclear Regulatory Commission
(NRC) licensees issued NRCs Order
Imposing Increased Controls and all
Radiation Control Program Directors and
State Liaison Officers Date
GC No.
Subject
Addressees
05/04/07 RIS-07-09 Examples of Recurring Requests for
Additional Information (RAIs) for 10
CFR Part 71 and 72 Applications
All holders of, and applicants for, a: (1) 10
CFR Part 71 certificate of compliance
(CoC) for a radioactive material
transportation package; (2) 10 CFR Part 72 CoC for a spent fuel storage cask; and (3)
10 CFR Part 72 specific license for an
independent spent fuel storage installation
(ISFSI).
06/27/07 RIS-06-27, Suppl. 1 Availability of NRC 313A Series of
Forms and Guidance for Their
Completion
All U.S. Nuclear Regulatory Commission
(NRC) medical-use licensees and NRC
Master Materials licensees. All Radiation
Control Program Directors and State
Liaison Officers.
05/15/07 RIS-07-10
Subscriptions To New List Server
For Automatic Notifications Of
Medical-Related Generic
Communications, Federal Register
Notices And Newsletters
All U.S. Nuclear Regulatory Commission
(NRC) medical-use licensees and NRC
Master Materials licensees. All Radiation
Control Program Directors and State
Liaison Officers.
08/31/07 RIS-07-13 Verification of the Authenticity of
Materials Possession Licenses
All U.S. Nuclear Regulatory Commission
materials licensees. All Agreement State
Radiation Control Program Directors and
State Liaison Officers.
09/07/07 RIS-07-18 Data for Updating the Interim
Inventory of Radioactive Sources
All U.S. Nuclear Regulatory Commission
(NRC) Part 40, Part 50, Part 70, Part 72, and Part 76 licensees and certificate
holders who are authorized to possess
sources of radioactive material
at the Category 3.5" (as defined below)
activity or higher.
10/04/07 RIS-07-23 Date For Operation Of National
Source Tracking System
All licensees authorized to possess
Category 1 or Category 2 quantities of
radioactive materials.
All Radiation Control Program Directors
and State Liaison Officers.
Note: A full listing of generic communications may be viewed at the NRC public website at the following address:
http://www.nrc.gov/Electronic Reading Room/Document Collections/Generic Communications