ML20125C340
| ML20125C340 | |
| Person / Time | |
|---|---|
| Issue date: | 04/08/1982 |
| From: | Kinneman J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Miller V NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20125B114 | List: |
| References | |
| FOIA-92-93 NUDOCS 9212110151 | |
| Download: ML20125C340 (3) | |
Text
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APR0 U32 E)dt1917L MEMORANDUM FOR:
Vandy L. Miller, Chief, Materials Licensing Branch, Office of Nuclear Materials Safety and Safeguards FROM:
John D. Kinneman, Chief, Materials Radiological Protection Section, Region I ST. MARGARET'S HOSPITAL, HAMMOND, INDIANA .
SUBJECT:
On March 10, 1952, I received a telephone call from Mr. Eric Ridout, Manager of Regulatory Affairs, Atomic Energy of Canada, Ltd., Ontario, Canada. Mr.
Ridout indicated that he was very concerned about the handling of some recent problems with a teletherapy unit located at the subject hospital. "r. Ridout stated that Neutron Products, Inc., Dickerson, Maryland, had recently installed a new source in a Theratron, Junior, Serial Number 70, teletherapy unit located at this hospital. From recent discussions with Mr. Pat Clemans, an. employee of St. Margaret's, (219-932-2300) he determined that the source installed had an exposure rate of 100 rads per minute at 55 cm which is equivalent to 30 RMM. Following installation of this source, measured radiation levels at the surface of the head over the dome were 70 miiltrem per hour and at one meter, 30 millirem per hour. Based o.n a review of AECL file documents for this specific unit, Mr. Ridout concluded th.at-there is a great likelihood that some error was made in the reassembly of the unit.
He believed that NRC and the licensee were cons.idering adding additional shielding to the outside of the head and wanted to express his strong opposition to this course of action. It was Mr. Ridout's guess that one of two errors had been made. In this From particular unit, the source drawer can be his calculations of the original made of tungsten or uranium.
manufacturing surveys of this unit, Mr. Ridout believes that a 16 to 18 RMM source would be possible with a tungsten drawer and a 30 to 35 RMM source would be possible with a uranium drawer. Therefore, he concluded that a tungsten rather than a uranium source drawer might have been used and would have caused the problem observed. Additionally, even if a uranium scurce drawer was used, if a tungsten or steel spacer had been used behind the source, this might have been expected to cause the elevated radiatien levels.
The spacer behind the source is a significant portion of the shielding in the come area.
Apparently, the proposed corrective action is to place a pad of attenuating material, such as lead, over the area of increased radiation level. Mr.
Ridout pointed out several problems with this course of action. The firs:
problem would be that two to three inches of lead would be required to recuce the radiation level to an acceptable level. This would require a mass of about 150 pounds. A similar mass would have to be added to the counter 9212110151 920504. K&'
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weight, resulting in a total increased weight .of at least 300 pounds resulting in an increased load on the gantry which was not included in_the original engineering analysis. This extra load would also bear on the drive "
mechanisms, of gears, and motors. This is an isocentric unit and an increase in size of the dome area would cause the unit'to collide with the toe bearing when it is rotated. In addition, Mr. Ridout was concerned that the method of securing the material, whether it be welding o- bolting, might cause a problem, with the main head shielding, such as cracking.
I have provided this information to P. Vacca and D. Sreniawski, Region III, for such action as is deemed appropriate. I plan no additional action unless information is developed which indicates Neutron products acted improperly or failed to follow their procedures. Since they were working under_an NRC-241, we would like to follup on this aspect or be able to refer it to the State of-Maryland, if it appears appropriate. .
, w chn D. Kinneman, Chief, Materials Radiological' Protection Section cc: j
- p. Vacca, NMSS V D. _ Sreni awski, RIII
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D* tribute /[/ TELETHERAPY NOTICE Five Year Inspection /j~
INSTALL: Source /T/ Unit /~/ RDOVE: Source /~/ Unit /~/ SERVICE [~/ ifarranty /""/
Approved bF TWk Dato ,4/1/8l Revisions: No./Date 2: 6-28-82 2:-7/22/81l MEDICAL PHYSICIST 3: 7/24/81l CUSTOMER THERAPIST.
Address: St. Maigaret W Hospital -
, Mr. Charles riffith MSMMg Avenue Hammond, Indiana 46320 -
Fee Included: Yes /~/ No /7/
?hene: 219/932-2300 k9/bhSN0 b **
) . O. No./ Agreement Date'd 6/11/81 Notified of Delivezy Date 7/22/71 By VMB XMc035%Xym # E0993 - 6/11/81 IDENT. CURIES MANUF.
30URCE INSTALLED: Model No. NPI-20-1900w S/N @9[ Front Slug 82739
\ctivity: Curies 1650 Date 6/1/82* Rear Slug .; _____' l
) rawer Installed: o. S15""/9. . Pb.g.U. - Output: Predicted 1880 Weasured/gfo[DateB/2) 30URCE REMOVED: Model No. [ ?_ M_ -- S/N O Manufacturer'/IEEL
\ctivity: Curies [c o , Date 0 @ d . Output: Predicted _
Measured /fst Datej
)r wer Removed: No. &;iJEl .S2.66"7 Pb.W.U.
JNIT: Manufacttirer AECL Hodel No.Theratron Jr Head Model C ?!N Nstomer License No. 13-02047-03 Status gegen OK fo2' State Approval Given Per Amendment nesdad- 410 idJs si. --
11cyctor - Type freight Capacity i Ceiling Height Coading Dock {X/Yes (/?
hmp-/[/Yes /~/ No Length M haeY -nk-#44/ Slope 2-3 0 -
- loors - Types _ Tile over concrete Coverin;.' Required yes
.EERAPY: Other Units _
Simulator - Yes [j~ No /~/
tros Monitor - Yes G No /~/ Type Backup - Yes 7 No /~/ Type IXTRAS: Field Use Only - Parts Extra Labor -
Man / Hours NO. READING EST. DOSE iource Installer tiif oW. Dosimeter: Whole Body l9hio (ba/( Wrist $c 48 sssistant dLFb& OdW[h/' Dosimeter: Whole Body T2co. M/. Wrist [O d[.
,ssistant Dosimeter: Whole Body Wrist iCHEDULE: Load Install Thurs..Auc. 13.' 'I981 Noon Completed iPECIAL CONSIDERATIONS: PRIMARY C0hTACT: Mr'.* Richttd ' Peterson, R. T.
12XRKliXXX'IXIIiMXX%RXM11 dix 31 Requested plywood be used on floors; was used at previous installation, f3 No problems with unit. * '
fjt Maximum loading is 1900 RIM-should not be exceeded.per Charles Griffith. -
59XL7PP4hUAM$lMSXTaTrumEqdm/W(
Jsff use tungsten drawer and maximum depleted uranium shielding.
Mr. Peterson must authorize. use of elevator, as serviceman needs to relcase limitation switch prior to use. Serviceman will be present at 12 noon, ur, r:vi fct s u.; ; t r. .,1 3 3 .i . . v,,,-u n v en no whar t ha unit will be available for