IE Circular No. 80-24, AECL Teletherapy Unit Malfunctions
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION ENFORCEMENT
WASHINGTON, D.C. 20555
December 2, 1980
IE CIRCULAR NO. 80-24: AECL TELETHERAPY UNIT MALFUNCTIONS
Description of Circumstances:
During the past several months NRC has continued to receive reports of
malfunctions of AECL teletherapy units, Models Theratron 60 and 80 and
Eldorado 6 and 8. According to these reports, malfunctions are occurring
with the power cord takeup reel of the beam defining projection lamp.
The malfunctions may have two possible consequences. First, the power cord
from the malfunctioning takeup reel may jam the source drawer mechanism and
prevent its return to the source "off" position. This condition can cause
unnecessary exposure to both technicians and patients. Second, the loose
cord may prevent the source drawer mechanism from going to the full "on"
This condition may not be readily detected by the machine operator and thus
may result in an incorrect dose being administered to the patient.
Under a medical device recall action, AECL has notified all known users-of
beam teletherapy, units, Models Theratron 60 and 80 and Eldorado 6 and 8
concerning potential malfunction problems. If you are a user of one of these
Teletherapy Units you should have received "Warning Notices" WN-80-1,
WN-80-2, WN-80-1A and WN-80-1B.
Additionally, NRC investigators have noted that improper actions of
operating personnel at the time of equipment malfunction may further
aggravate the situation and contribute to the unnecessary exposure. However,
these exposures can be minimized by licensees if their operating personnel
are trained to promptly detect and react to equipment malfunctions in
accordance with approved written operating and emergency procedures.
Notice to Teletherapy Licensees:
Current NRC regulations and licensing procedures require teletherapy
licensees to develop, maintain, and use the following procedures and
radiation monitoring equipment:
o Written operating, emergency and maintenance procedures.
o A program for inspection, testing and servicing of equipment components
that are critical to safe operation.
December 2, 1980
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o A radiation monitoring device that continuously monitors the
teletherapy beam condition.
These procedures and monitoring system are intended to improve safe
operation of the equipment under both normal and abnormal conditions.
In addition to the above requirements, this circular identifies certain
other actions which persons licensed by NRC pursuant to 10 CFR Part 35
should take. These are noted below.
NOTE: Items 1, 2 and 3 are directed to those licensees authorized to use
AECL, teletherapy units Models Theratron 60 and 80 and Eldorado 6
and 8. Items 4 through 10 are directed to all teletherapy
1. If you have not received "Warning Notices" WN-80-1, WN-80-2, WN-80-1A
and WN-80-1B you should immediately contact an AECL service Centre or
the Regulatory Affairs Branch, Quality Assurance Division, AECL-CP,
P.O. Box 6300, Ottawa Canada (tel. 613-592-2790).
2. If you have received the "Warning Notices" identified in Item 1 above,
you should implement the requested actions in those "Warning Notices".
Please give attention to "Warning Notice" WN 80-1B.
3. Cooperate with AECL in scheduling time for machine modification in
accordance with remedial action as described in their final notice.
4. Verify that emergency procedures are posted in accordance with license
conditions and that operating personnel are familiar with them.
5. Establish a schedule and conduct periodic drills in response to
simulated emergency situations.
6. Follow manufacturers' recommendations for inspection and maintenance
and, in particular, those concerning replacement of "critical
components". Guidelines for maintaining and procedures for inspection
of teletherapy equipment are also contained in ANSI N 499-1974 and ANSI
7. Instruct operating personnel to be alert and report to responsible
management any changes from normal operating characteristics. An
example would be slower-than-normal source travel.
8. Initiate emergency response in the event that both "source on" and
"source off" signals are energized simultaneously. This is an
indication of less than full travel on the source drawer.
9. Following any malfunction or problem identification, take the equipment
out of service until it is investigated and repaired as necessary.
10. Cooperate with manufacturers in engineering assessments, equipment
modification and recall actions.
December 2, 1980
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The information contained in this circular should be brought to the
attention of all persons involved in the administration and operational
aspects of teletherapy.
No written response to this circular is required. If you need additional
information regarding this subject, please contact this office.
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