Information Notice 2009-15, Varian Medical Systems Varisource High Dose-Rate Remote Afterloader Events: Source Retraction Problems
| ML092120085 | |
| Person / Time | |
|---|---|
| Issue date: | 08/28/2009 |
| From: | Robert Lewis NRC/FSME/DMSSA |
| To: | |
| Poy, Stephen 301-415-7135 | |
| References | |
| IN-09-015 | |
| Download: ML092120085 (5) | |
ML092120085 UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF FEDERAL AND STATE MATERIALS
AND ENVIRONMENTAL MANAGEMENT PROGRAMS
WASHINGTON, DC 20555
August 28, 2009
NRC INFORMATION NOTICE 2009-15:
VARIAN MEDICAL SYSTEMS VARISOURCE
HIGH DOSE-RATE REMOTE AFTERLOADER
EVENTS: SOURCE RETRACTION PROBLEMS
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 to alert addressees about recently reported events at
three different locations where service engineers experienced problems with the VariSource
HDR during source retractions. During all of the incidents, the source wire became stuck
outside of the afterloader and required the Varian personnel to use the manual-retract handle to
return the source to a safe-shielded position. The NRC expects recipients to review the
information for applicability to their facilities and to consider actions, as appropriate, to avoid
similar problems. However, suggestions contained in this information notice are not new NRC
requirements; therefore, neither specific action nor written response is required.
The NRC is providing this information notice to the Agreement States for their information and
for distribution to their medical use licensees, as appropriate.
DESCRIPTION OF CIRCUMSTANCES
The NRC received an event report involving VariSource HDR devices at three separate facilities
where service personnel using standard procedures were unable to retract the source into the
shielded tungsten safe, following source replacement. This event report, required in
accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 30, Rules of
General Applicability to Domestic Licensing of Byproduct Material, and 10 CFR Part 21, Reporting of Defects and Noncompliance, involved three separate cases that occurred
between December 2, 2008, and December 30, 2008. In all cases, the service personnel had
completed a source exchange and were in the process of conducting positional verification
testing of the new source. During the testing, the source wire failed to return to the shielded
tungsten safe, requiring the service personnel to implement the emergency procedures. The
service personnel first attempted to retrieve the source by depressing various emergency
buttons located on the HDR device and device console. When this proved unsuccessful, the service personnel turned the manual-retract handle on the HDR device and successfully
returned the source to the tungsten shield.
Preliminary data suggest that the restrictions on the movement of the source wire occurred
internally within the HDR, caused by buildup of material within one of the components along the
source wire path. Specifically, in two cases, service personnel reported the presence of
compacted black dust in the source guide fixtures near the source drive. None of the incidents
occurred during patient treatment; however, the possibility of this happening in the future
cannot be ruled out.
DISCUSSION
All of the incidents occurred because of an accumulation of dust buildup in the source wire
path. It has been determined that the buildup is composed of dust materials produced from
normal wear within the device. Analysis of the dust particles has shown that the dust is
composed of the same material as the nickel titanium source wire. However, an analysis of the
affected source wires, conducted by visual and mechanical examination, has shown that the
integrity of the wires was not compromised in any of these events.
This information notice reminds licensees to be aware of the potential problem associated with
the accumulation of dust in these devices, leading to source wire constrictions. As a result of
the problems caused by the buildup, Varian implemented special maintenance procedures, including the routine cleaning of any components exhibiting dust buildup on a regular basis.
Initially, Varian service personnel conducted this cleaning at every source exchange; as the
buildup rate of dust has become known, Varian has increased the frequency accordingly.
Varian has released information regarding these events to its customers in Customer Technical
Bulletin CTB-VS-640A. The bulletin reminds customers to review their emergency procedures
in the event that the source wire must be retracted using the manual-retract handle. The
bulletin also asks that customers immediately report any errors that occur upon active wire
retraction with error code 1A, class 2, Active wire drive slippage..., which may indicate that the
HDR is trending toward an internal path constriction.
Furthermore, licensees should be aware of the following:
A user-resettable error code of 1A, class 2, Active wire slippage... should be reported
to the manufacturer, Varian, immediately.
To shield the source, personnel would need to implement emergency procedures, which
may require turning the manual-retract handle.
The VariSource HDR is approved for use with an 11-curie iridium-192 source. With
such a source the exposure rate is 20.7 rem per hour at 50 centimeters. The exposure
rate from an unshielded 10-curie iridium-192 source is 18.8 rem per hour at 50
centimeters (as referenced in the Varian VS2000 SSD).
After an event where the source has become stuck outside of the afterloader, patient
treatments should not resume until repairs are complete.
CONTACT
S
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 regional office.
Robert Lewis, Director /RA/
Division of Materials Safety
and State Agreements
Office of Federal and State Materials
and Environmental Management Programs
Technical Contacts: Stephen Poy, FSME
(301) 415-7135
E-mail: Stephen.Poy@nrc.gov
Enclosure:
List of Recently Issued FSME
Generic Communications
CONTACT
S
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 regional office.
Robert Lewis, Director /RA/
Division of Materials Safety
and State Agreements
Office of Federal and State Materials
and Environmental Programs
Technical Contacts: Stephen Poy FSME
(301) 415-7135
E-mail: Stephen.Poy@nrc.gov
Enclosure:
List of Recently Issued FSME
Generic Communications
ML092120085 OFC
FSME/MSSA
FSME/MSSA
FSME/MSSA
FSME/MSSA
FSME/MSSA
FSME/MSSA
FSME/MSSA
NAME
SPoy
JJankovich
AMcIntosh
ADWhite
JFoster
JLuehman
RLewis
DATE
07/03/09
08/05/09
08/19/09
08/05/09
08/12/09
08/18/09
08/28/09 OFFICIAL RECORD COPY
IN 2009-15 List of Recently Issued Office of Federal and State Material
and Environmental Management Programs Generic Communications
Date
GC No.
Subject
Addressees
03/30/09 IN-2009-07 Withholding of Proprietary
Information from Public Disclosure
All current holders of and potential applicants
for licenses, certificates of compliance, permits, or standard design certifications, as
well as any other persons submitting a request
that information be withheld from public
disclosure under the provisions of Title 10 of
the Code of Federal Regulations (10 CFR)
Section 2.390, Public inspections, exemptions, requests for withholding.
07/27/09 IN-2009-12 Exempt Distribution Licensing
Requirements For Irradiated Gemstones
All holders of NRC exempt distribution licenses
authorized to distribute irradiated gemstones.
Organizations associated with importing, distributing or selling irradiated gemstones or
jewelry containing irradiated gemstones. All
Radiation Control Program Directors and State
Liaison Officers.
07/29/09 IN-2003-22, Supplement 1 Heightened Awareness for Patients
Containing Detectable Amounts of
Radiation from Medical Administrations
All U.S. Nuclear Regulatory Commission (NRC)
medical-use licensees and NRC master
material licensees; all Agreement State
Radiation Control Program Directors and State
Liaison Officers.
04/29/09 RIS-2009-05 Uranium Recovery Policy Regarding: (1)
The Process for Scheduling Licensing
Reviews of Applications for New
Uranium Recovery Facilities and (2) The
Restoration of Groundwater at Licensed
Uranium In-Situ Recovery Facilities
All holders of operating licenses for uranium
recovery facilities and all companies who have
submitted applications to construct new
uranium recovery facilities of all types
(conventional mills, heap leach operations, and
in-situ recovery facilities) or letters of intent to
submit such applications.
05/07/09 RIS-2009-07 Status Update for the Implementation
of NRC Regulatory Authority for Certain
Naturally Occurring and Accelerator- Produced Radioactive Material
All U.S. Nuclear Regulatory Commission
material and fuel cycle licensees. All Radiation
Control Program Directors and State Liaison
Officers.
07/13/09 RIS-2009-09 Use Of Multiple Dosimetry and
Compartment Factors in
Determining Effective Dose Equivalent
from External Radiation Exposures
All U.S. Nuclear Regulatory Commission
licensees, Agreement State Radiation Control
Program Directors, and State Liaison Officers.
Note: This list contains the six most recently issued generic communications, issued by the Office of Federal and State
Materials and Environmental Management Programs (FSME). A full listing of all generic communications may be viewed at
the NRC public website at the following address: http://www.nrc.gov/reading-rm/doc-collections/gen-comm/index.html