ML20136D336
| ML20136D336 | |
| Person / Time | |
|---|---|
| Site: | 07002003 |
| Issue date: | 04/03/1980 |
| From: | Stunkard B HIBBING-TACONITE CO. |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20136D340 | List: |
| References | |
| 15991, NUDOCS 8005160104 | |
| Download: ML20136D336 (16) | |
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Safety and Safeguards U.S. Nuclear Regulatory Co= mission Washington, D.C.
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Dear Sir:
Attached is information submitted to support our request for the renewal of our Special Nuclear Materials License (SNM-1558) authorizing Hibbing Taconite Company, Pickands Mather & Co., Managing Agents fcr ownership, acquisition and utilization of the described special nuclear materials.
Enclosed is a check for S110.00 made payable to the U.S. Nuclear Regulatory Commission.
Should there be any questions, please contact Mr. R. C. Ives at (218)262-5950, Extension 305.
Sincerely,
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' hNALYEER
Pu8Be SPECIFICATIONS 1.
Overall. diameter and thickness as specified on drawing below.
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Isotope Pu-238 with Beryllium.
3 Neutron emission after fabrication must be measured and specified, but not to be less than 2.0 x 107 n/sec +20%; -0%.'
4.
Approximate void volume will be furnished by manufacturer.
5 construction material to be 304 stainless 9 teel or its equivalent.
capsule to be ' weld scaled.
- 6.. capsule t'o be engraved with isotope, activity and assay date on,back plate.
e 2.25 0.060 -
2.00 0.120
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0.060-i ACTIVE MATERIAL STAINLESS STEEL l'
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Pu88c Source
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These items are referenced to Ohmart Nuclear Moisture Gauge (Model NMG-1):
3.
Richard A.
Bauer Mr. Bauer is the Superintendent of the Agglomerator and has responsibility for all activities at the Agglomerator. This includes the operation of the radioactive devices, plus the health and safety of personnel working with or around these devices. Although Mr. Bauer does not have any formal training in Radiation Safety, he is aware of the hazards of ionizing radiation. He will be assisted in matters of radiation safety and protection by the Hibbing Taconite Company Radiation Protection Officers.
Mr. Bauer's educational background is a B.S. degree in Geology and a B.S. degree in Mining.
4.
The plutonium / cesium source will be used as an integral part of the moisture gauge supplied to Hibbing Taconite Company by Ohmart Corporation, a
4241 Allendorf Drive, Cincinnati, OH 45209. The purpose of the gauge is to determine moisture content in iron ore filter cake on a conveyor.
5.
The onMART Bulk Moisture Gauge is a continuous, noncontact instrument for determining the percentage, by weight, of moisture contained in a bulk material.
The gauge continuously samples a cross-section of material, simultaneously measuring water content.and bulk mass content, to provide a signal corresponding to the percent moisture of the material being 1
measured.
The Bulk Moisture Gauge consists basically of two commonly housed i
sections, a neutron section for measuring moisture and a gamma section for measuring bulk mass.
The neutron and gamma gauge geometries are interrelated, providing a precise measurement of the same cross-section of bulk material. The signal outputs of the moisture weight and total weight are properly converted into signals useful for feeding into a percent moisture computer which provides an output for percent moisture recording. The percentage of moisture present is determined electronically by dividing the neutron signal (moisture weight) by the gamma signal (total bulk weight).
The computer also provides a signal which can be fed into an optional bone-dry computer. The bone-dry computer accepts this signal and an 4
external total weight signal to provide a totalized bone-dry digital counter readout.
A further option of providing a bone-dry control signal is also available.
The gauge configuration used at Hibbing Taconite Company is a C-Frame i
housing for conveyor application. A combination neutron and gamma radiation source is mounted opposite a pair of detectors, neutron and gamma, and their associated components.
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~10-I The basic electronics and controls are housed in a panel-mounted cabinet. Additional electronics-are housed in the C-frame.
The neutron measuring section consists of a radiation source of fast neutrons (average energy approximately 4 to 5 MEV) and a slow neutron detector, a gas proportional counter tube.
Some of the fast neutrons, in passing through the material to be measured, are stopped by the material and some pass directly through the material unaffected. Some of the fast neutrons, due primarily to collisions with hydrogen nuclei, lose a large part of their energy to become thermalized neutrons.
Only the slow (thermalized) neutrons are sensed by the detector.
Therefore, the ratio of the slow neutrons reaching the detector to the fast neutrons leaving the source is directly related to the hydrogen content of the material being measured. Since water contains 11.1%
hydrogen by weight, the hydrogen measurement performed by the neutron section of the gauge indicates the amount of water present in the process material.
In some heavy material applications where a greater proportion of the neutrons are stopped by the process material, a moderator (i.e.,
material high in hydrogen content) is placed between the detector and path of transmission. The moderacor slows down the fast neutrons'.so that they can be sensed by the detector.
This method uses the ratio of fast neutrons passing completely thrc 2gh the material to the. fast neutrons leaving the source, which is inversely related to the' mat'erials hydrogen content, to indicate mmount of water present in the process material.
The gamma measuring section is comprised of a gamma-ray-emitting-radioactive source and an ion-chamber gamma detector. As the radiation passes through the process material, some of the gamma rays are absorbed.
The amount of radiation reaching the detector, thus, is a direct measure of the total material weight. Since gamma radiation absception is a function of total mass in the radiation beam, the output signal of the gamna measuring section represents bulk weight (water plus
" bone-dry" material).
The source material used is Cs-137, which emits 0.66 MEV gamma rays.
The detector is a gas-filled ionization chamber.
6.
The sealed source used in the Ohmart Model NMG-1 is a Pu238/Cs-137 combination source. The combination source contains two (2) sources at 15 mci cach and one (1) source of Pu238 at 13 curies. The scaled source is Ohmart Corperation's Model B-18248, 7.
The gauges will be utilized on iron ore filter cake conveyors (FC-3 and FC-23) near the head pulley in the Agglomerating plant. This area is located near the' top of the Agglomerating plant. There are no personnel which routinely work in this. area and maximum exposure in this area is estimated at less than 20 mR/yr.
Leak tests will be run on the gauges at' leastsonce every six months under normal operation. The leak test procedure to be used is attached.
In the event that the use of the gauges is discontinued, the removal and disposal of the radioactive material will be handled by Ohmart Corporation. Itibbing personnel will not remove the source from the source holder.
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6 LEAK TEST PROCEDURE FOR OHMART NMG-1 The gauge will not be dismantled or disassembled in order to leak test.
Testing of the external seams, flanges and end plate is adequate.
4 1.
Position the shutter actuator to the closed off position.
In the event that the shutter actuator is frozen, or appears damaged, notify Ohmart.
i 2.
Obtain as many cotton-tipped applicators as are deemed necessary and slightly moisten.
(Use water, alcohol or other solvent.)
l 3.
With the shutter closed, wipe the areas of the source housing assembly at the following locations: Around the seams at both ends of the source holder pipe and the heads of screws (4) holding the source holder within the pipe.
(Care should be taken not to touch the Q-tips with the fingers following wiping operation.)
4.
Place a bottle containing the cotton tips in a matling tube, af ter securely sealing the bottle.
Fill out the information requested on the " Leak Test Request".
y 5.
Upon completion, place the information sheets back in the mailing tube and reseal.
6.
Use a self-addressed label to return to Bethlehem Steel Corporation (License No. 37-01861-02) or Ohmart for counting.
.I Upon receipt of the tube, the applicators will be counted on very sensitive equipment that has a demonstrated sensitivity and accuracy of
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1.0 x 10-5 Jici+ for Pu-238.
If the applicators are found to be free of I
contamination, a notice will be sent via mail in the form of a leak test certificate.
If the applicators 'are found to contain significant amounts of radioactive material, an emergency notification will be sent, via telephone or telegram, advising that the unit must be taken out of service and what additional actions should be taken.
l The Post Office Department regulations prohibit the shipment of radioactive material through 'the mails when the level of gamma radiation at the outer surface of the mailing tube exceeds 0.5 milliroentgens per hour. Therefore, the mailing tube will be surveyed with an Eberline E-530 survey meter with an HP-190 probe radiation detector prior to mailing.
If the levels exceed 0.5 milliroentgens per hour, Ohmart and the counting laboratory will be notified for further instructions,
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