ML20128J936
| ML20128J936 | |
| Person / Time | |
|---|---|
| Issue date: | 09/06/1996 |
| From: | Steven Baggett NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Abramson L, John Lubinski, Rameysmith A NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| SSD, NUDOCS 9610100231 | |
| Download: ML20128J936 (15) | |
Text
_ _ _ _
September 6, 1996
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MEMORANDUM TO:
John Lubinski, NMSS/IMAB Lee Abramson, RES/PRAB Ann Ramey-Smith, RES/PRAB Dan Lurie, OC/DBA Samuel Pettijohn, AEOD/RRAB FROM:
Steve Baggett, NMSS/IMAB Origina!SignedBy:
Chair, Steering Committee StevenLBaggett
SUBJECT:
MEETING OF THE STEERING COMMITTEE ON SEALED SOURCE RISK (SCSSR)
The second full meeting of the SCSSR will be held on September 17,1996, from 9:30 a.m. to 4:00 p.m. in Room T-8A1. The subject of the meeting is data.
Mr. Ryder, the principal investigator of the risk assessment, has drafted an overview of the subject of his assessment, the areas where he will need data, and the scope of his risk assessment. A copy of the document is attached. Please review the document to prepare for discussions at the meeting.
Attachment:
As stated Distribution:
SSSS Staff SSSS r/f NE02-SSD-7 L (.
p,e, 140 m k, DcwI-DOCUMENT NAME: a:\\scssr.m2 To receive a copy of this document. Indicate in the box:
"C" = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N" = No copy OFFICE NMSS/IM3p l
l l
l NAME SBaggetttV DATE 9/cj96 OFFICIAL RECORD COPY D5 8 Q ggg }M, @NdE8a b I
9610100231 960906 PDR RC SSD PDR
/
b Rough Draft Septeniber 5.1996 Comments 1
1 Overview The subject of the risk assessment, nuclear gauges in the recycling stream, is 2
4 illustrated in Figure 1 and discussed in the paragraphs to follow. The 3
environment of nuclear gauges, both in control and out of control, will be 4
discussed to show all of there aspects. A discussion of the data that is available s
in the various areas of the figure will show the data being sought to support the s
TIsk assessment and Some limitations because of the paucity of data. Then the 7
risk assessment itself will be discussed to show what will and will not be s
9 modeled.
1.1 Environment of Nuclear Gauges 1o The purpose of the risk assessment is to determine the risk of fixed nuclear u
gauges from which controls have been lost. The risk analysis considers both the 12 prevention of the loss of control and mitigation when nuclear gauges are out of a
control, giving rise to hazards.
14 The upper halfof Figure 1 shows both preventive controls for keeping nuclear is gauges in safe places moving along safe routes and mitigative controls when the 16 gauges get beyond regulatory controls into unintended places and routes. The 17 is black line/ arrows represent the routes, both within and out of regulatory 19 Controls.
The lower half of Figure 1 shows three physical areas where nuclear gauges can 2o he found. On the left is the movement within the regulatory regime among 21 licensees-gage vendors, industrial users, and other licensees. Two types of 2,
licensees are specific licensees and general licensees. Depending on the terms 23 of the license, a specific licensee can manufacturer, distribute, install, remove, 24 and service nuclear gauges. The general license allows for use and storage. In 2s the middle is the recycling stream, consisting of scrap metal collectors, 2s demolition and salvage contractors, scrap yards, and steel mills. On the right are 2,
the destination of products and byproducts, both during normal operations and 28 after a nuclear gauge has been smelted in a steel mill.
29 1
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j e
Requissed Unregulated
~
Prevennon Mingenen l
~
M onitor I
Regulatory m anufacturers t
agencies Radiation
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Detection Visual Detection Speceelse N
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Controls on Controls wh rais Construction on Use puenggere Beesseer I
BC Counpesities Inspecties ~
Shletding Investery BuEL CCOG
%g Labhag Labhag ssamme M
Training s Transfers ~
- Steeldtag Contamin ated Records
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prodyct &
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~i du st steel Vendors Industrial d
fspi,ipes,
,7 lD & S l (SL) r l MW site l 1 M j
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SL : GL
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>l LLW site l siest Landfill SL l
4 l Markets [
Unauthorized re.
Use Pb.
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Byproduct dai processors l LLW site l g
1 5 ifarardous 4=t waste site i
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Figure i Overview of nuc! car gauges passing through the recycling stream. HC = benign contamination GL = general licensee. LLW = low level waste. MW = mixed waste. SL = specific licensee.
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Rough Draft September 5.1996 Comments The preventive controls are the regulatory controls on both the manufacture.
transfer, and use of nuclear gauges. These controls are imposed by the NRC and 2
Agreement States. Nuclear gauges are manufactured by a vendor, a specific 3
i licensee authorized by a regulatory agency to manufacture and distribute nuclear 4
gauges. The controls built into an nuclear gauges are of three types:
s composition s
shielding 7
labeling a
Nuclear gauges are sold to many industries for a variety of purposes. The 9
gauges are essential to many industries for measure thickness, level, density, and to weight. The process lines are built with nuclear gauges as an integral 11 component; other types of measuring devices usually cannot be readily 12 substituted. Industrial facilities with nuclear gauges are licensees, subject to the u
regulations governing the use, storage, and disposal of the nuclear gauges. The 14 controls on the nuclear gauges during use are specified in the terms of the is license under which the nuclear gauge is issued.
16 The nuclear gauges are subject to inspection by the regulatory agency.
17 An inventory of nuclear gauges must be periodically taken.
1e Labeling must be maintained to clearly identify the gauge as containing 19 4
20 radioactive material.
1 There is usually at least some training, provided by the vendor or 21 required by the regulatory agency.
22 Adequate records must be maintained.
n The manufacturer of the nuclear gauge sell the gauges to industrial facilities.
24 Nuclear gauges can be returned to the manufacturers or another specific licensee.
2s When no longer of use, nuclear gauges can be sent to waste sites. The costs of 26 the transfers are represented in the shadows of Figure 1.
27 The mitigative controls are visual detection and radiation detection of nuclear 28 gauges in the recycling stream; this is the upper middle of Figure 1. For the 29 3
l
r Rough Draft
%:ptember $,1996 Comments most part, little radiation monitoring is done at the beginning of the recycling 1
stream. The volumetric flow of scrap metal is seldom sufficient tojustify the 2
expense of large portal monitors found further along the recycling stream.
3 Iland-held radiation detectors are possible along the stream, before the large 4
portal monitors, but in the beginning, even hand-held detectors are uncommon.
s Scavengers, gypsies, and peddlers do not have the resources to purchase and s
operate the devices. The primary means of detection is visual inspection, which v
may be impeded in the following ways:
a The labeling may be gone because of corrosive and hot environments.
9 t
The bulk of the scrap metal hiding the nuclear gauge to The orientation of the nuclear gauge so that the label is facing away for u
scrap collectors 12 Paint and dirt covering the labeling u
Lack of education about what to look for 14 Further along the recycling stream, the volume of scrap metal justifies the use is of sophisticated radiation detectors at the entrance and exists of scrap yards and is steel mills. As the scrap metal nears to time to be sent to a steel mill, the scrap 17 metal has been sorted, baled, and shredded, compacting the scrap metal. The is deleClion of nuclear gauges with radiation monitors is also be impeded.
19 The shielding of the nuclear gauge will reduce the radiation that can 20 21 reach the radiation monitor.
The high density of scrap metal adds additional shielding.
22 The background radiation will set a lower limit on alarm point.
23 Benign contamination, such as from sand, thorium welds, refractory 24 as brick, and people who have had nuclear medicine will cause false 26 alarms.
The detector has operating characteristics.
27 4
Rough Draft
$cptember 5.1996 Comments The electronic circuits processing the signals from the detectors must at 1
2 least do some processing of signals from detectors in varying background levels.
3 The operation of the monitoring equipment includes the maintenance, 4
the protocol for using the equipment, the setting of the alarm point, 4
s decision criteria for using the information from the monitor.
e These impediments are represented in Figure I by the shaded boxes over the
{
7 factors allownig for visual and radiation detection.
8
'lhe rCgulations governing the manufaClure, transfer, and use of nuclear gauges j
9 are for preventing nuclear gauges from entering the recycling stream. The block to the regulations form is represented by gray box next to the shaded area in Figure u
- 1. But the experience has been that the prevention is imperfect (hence the gray 12 instead of a black box); nuclear gauges have been found in the recycling stream u
and smelted at steel mills; this is represented by the horizontal line/ arrow from u
the gray box going through the large white arrow to the mill box. Circumstances 1s under which the regulatory controls sometimes deteriorate include the following:
u In an industrial facility, other concerns about high pressures, high u
temperatures, and massive moving objects are more acute. The primary is Concern at an industrial facility is not the nuclear gauges; it is 19 production.
Hence, records become inadequate, the corporate 20 knowledge of the nuclear gauges fades and staff come and go, the 21 labeling deteriorates, or the inspections are missed.
22 The staff who maintain, renovate, and scrap plant systems might not be 23 those same staff who are responsible for and have knowledge of the 24 nuclear gauges.
2s During normal maintenance activities when painting is done to protect n
metal structures, nuclear gauges may be painted as well, making them n
indistinguishable from non-radioactive structures.
as Industrial environments may obliterating labels because the are 29 corrosive, abrasive, dusty, or hot,.
30 5
Rough Draft September 5.1996 Comments An industrial facility may be moth. balled or abandoned. When this i
happens, the nuclear gauge is no longer a part of the aspects of 2
production because there is no production.
3 Regulatory agencies have insufficient resources to frequently inspect 4
every nuclear gauge that is distributed.
s The loss of control is not just a matter of the regulations and regulatory s
v resources; it is also a matter of deterioration of the controls in their use and the oversight to maintain the controls.
e There are other, mostly unknown, ways that nuclear gauges are lost from the 9
controlled pathways of the regulated area; this is represented in Figure 1 by the 10 line/ arrows coming down from the gray box. The pathway to landfills is likely u
12 minor. Scrap metal is valuable; little of it, and hence nuclear gauges, are disposed. Landfills may be used for illegally disposing of nuclear gauges.
u Another pathway is through unauthorized use; nuclear gauges are knowingly or 14 unknowingly used without regulatory controls. Still another pathways indicated 1s by a question mark; nuclear gauges are disappearing-where they are gone is 16 anyone's guess, n
A scrap dealer receives a shipment of metal that contains radioactive is material. Regulators say that the dealer must pay for the disposal of the 19 gauge. That night, the dealer's yard is broken into and the pile of metal 20 containing the nuclear gauge is stolen (Ref. 2).
21 A shipment of metal arriving by truck to a scrap yard or mill is rejected 22 a
because there are indications that it contains radioactive material. The radiation levels are not high enough to require the recipient to inform the 24 authorities. The driver is told that the shipment can be taken somewhere 2s 2s else (Ref 2).
People do not want to be held responsible for the disposition of the nuclear n
gauge that was not theirs until they unknowingly took procession of them when 28 taking procession of scrap metal. People do not want to incur costs for delays 29 in their businesses. Dumping a shipment is less expensive than taking a chance 30 of being held responsible for the disposal of a nuclear gauge. Because n
economics drives the recycling stream, the least expensive way is usually taken.
32 6
Rough Draft September 5.1996 Comments In the lower middle right of Figure 1, the large white arrow represents the 1
recycling stream. Scrap metal collectors (scavengers, gypsies, peddlers),
2 demolition contractors, and salvage contractors are at the beginning of the 3
stream. Scrap yards that process (grade, cut, bale, shred, shear) the scrap metal 4
are further along the stream. Steel mills that use the scrap metal are at the end s
of the stream. Scrap metal shipments may cause radiation alarms along the c
recycling stream, causing the recipient to reject the shipments. The rejections 7
are represented by the white arrows curling back. The rejections may occur at e
the scrap yards or at the mills. A shipment that has caused a radiation monitor 9
to alarm can follow several scenarios, depending on the practices at a facility:
1o The shipment is taken apart. The disposal of the radioactive material, be 11 it NORM, thorium welds, or a nuclear gauge, is returned to the sender.
12 The shipment is taken apart. If the alarm is attributed to zircon sand or 13 a thorium weld, the shipment is accepted. If the scrap metal is suspected 14 of being contaminated, then the vehicle is reloaded and the shipment is is rejected.
16 The shipment is returned under DOT exemption 10656 if radiation levels 17 from the shipment are 50 mR/hr or more.
28 The staff at some facilities will inform local authorities that a shipment 19 has been rejected regardless of the radiation levels.
2o The recipient does not permit the shipment to enter the facility at all.
21 22 Radiation measurements are not taken. The driver takes to another facility or dump the shipment.
23 At the end of the recycling stream, represented at the lower right of Figure 1, the 24 scrap metal enters the steel mills. Both integrated mills and mini-mills consume 2s scrap metal. In the United States, little iron ore is used to make steel.
2s Scrap metal that enters the mill is smelted to make products for customers.
27 The gray line on the right in Figure 1 indicates the flow of products and 2e byproducts to the markets. The steel is made into products for direct use, such 29 as reenforcing rods and plates, or sent to other industries that will reheat the steel 30 and roll it into other products. The furnace dust is sent to processors where 31 7
Rough Draft September 5.1996 Comments metals are removed to be recycled and used in other industries (Zine is sent to 1
a zine plant. Lead is sent to smelter. Copper is sent to a smelter). The material 2
left in the processor is rich in iron, hence. it Is referred to as iron rich material 3
(IRM), which is used in a variety of products, such as aggregate material in 4
asphalt, an iron ingredient in cement, and a construction aggregate. Some IRM s
is returned to steel mills for to be smelted. Cadmium is sent to a hazardous s
Waste landfill because the markets for this metal are depressed. A liquid 7
containing halides is pumped into deep injection wells. Fumace dust may also 8
be sent to hazardous waste sites where it is stabilized, then buried. Fumace dust 9
can be glassified and used in a variety of products, such as roofing material, 10 sandblasting grit. The destination of the dust chosen by a mill is the economical 11 12 pathway.
The black rectangle over the gray line indicates that contaminated products and u
byproducts are unlikely to leave the mill because these materials will likely pass 14 by a radiation monitor at some pont before leaving the mill:
is Steel may pass through nuclear gauges as it is poured or rolled.
16 Steel products may pass through portal monitors when leaving the mill.
17
+
Furnace dust is monitored either at the baghouse or at a portal monitor is when leaving the mill.
19 Furnace dust may monitored when entering a processing plant.
2e
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When a sealed source is smelted along with scrap metal, the steel and furance 21 dust is contaminated. When a '37Cs source is smelted, most of the cesium 22 vaporizes and boils off the melt with the furnace dust. The refractory brick 23 lining the fumace and ladle will also be contaminated. Little of the cesium will 24 remain in the steel. The furnace dust is no longer a hazardous waste by a mixed 2s waste (heavy metals and radioactivity). When a "Co source is smelted, most of 2e the cobalt remains in the steel as an alloy. In Figure 1, these pathways are n
denoted by the dotted black line to indicate that the sealed source has changed 28 from its encapsulated form to a dispersed form in the steel and the furance dust.
29 The contaminated furnace dust can be sent to a processor where it is solidified, 30 31 then buried in a on-site mixed waste site. The steel can also be sent to a processor where the contamination is removed; the reclaimed steel can then be 32 33 sold as can other steel. The contaminated steel can also be sent to a low level waste site. Whether contaminated steel is reclaimed or disposed depends on the 34 volume of steel and the extent of the contamination; the deciding factor is cost.
3s 8
)
1-3 Rough Draft September 5.1996 Comments t
t
.l.2 Data l
l 1.2.1 Regulatory agencies 2
i 1.2.1.1 Nuclear Materials Events Database (NMED) 3 i
j 4
NMED is a database of reported incidences were control over devices containing scaled sources was lost. The incidences are made known by the s
licensee and regulatory inspectors. Reporting requirements are specified under s
2 7
Part 20 of Reference 2.
e NMED is a database-a collection ofinformation organized especially for rapid i
a search and retrieval. This differs from a sample, which is a part of a group that i
9 j
was chosen by some means to be included while other members of the group are zo t
11 excluded.
1 i
12 1.2.1.2 Yusko Database
]
13 James Yusko, Pennsylvania Department of Environment Protection, has been collecting reports of when radioactive material was found. The Yusko Database l
1e l
differes in that in some respects it goes beyond NMED. NMED is based on the 1s reporting requirements of Part 20 whereas the Yusko Database has no is j
17 restrictions:
i The information of tae Yusko Database comes from many sources, some of 28 1
j which also are part of NMED:
is Preliminary Notice of Occurrence (PNO) reports 2o Morning Reports j
21 Notices from mills of detections in shipments of scrap metal 22
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Notices from scrap yards of detections in shipments of scrap metal 22 Steel Manufacturers Association, who asks there member mills to report 24 detections in shipments of scrap metal 2s Notices from people in other states, who know of this database those the 26 27 CRCPD.
2e The Yusko database focuses on finds of radioactive material whereas NMED focuses on missing radioaClive material. Finds are not reportable under Part 20 29 9
Rough Draft September 5.1996 Comments (Ref. 2). That the Yusko Database emphasis finds is an important aspect of the 2
risk from nuclear gauges because two criteria must be met to report a nuclear 2
gauge as missing for whatever reason:
3 The licensee must know that the nuclear gauge is in their procession.
4 The licensee must realize that the nuclear gauge is missing.
s These criteria may be difficult to meet because of the reasons listed in Section 6
1.1 (page 5).
7 e
1.2.2 Radiation monitor manufacturers Large manufacturers of the radiation monitors have telecommunications with the 9
monitors sold to customers, overseeing the operations of the portal monitors.
io They have records of when monitors have alarmed, been turned off, and u
u disconnected.
The risk assessment will model the chances of detecting a sealed source in the u
shipment of scrap metal. Characteristics of the shipments, such as density and 24 measured attenuation factors would be of much use. Three references are being 1s pursued:
is The Steel Manufacturers Association, a trade association representing 17 minmills, is sponsoring a tests on the performance of monitors. The is results of the tests are being sought to support models of the monitors.
19 2o If the SMA will not release the information, then the manufacturers who participated in the test will be approached.
21 A scrap metal broken did one test where a check source was buried in a 22 shipment of the densest grade of scrap metal.
23 The manufactures have estimates of the reliability of their monitors of 24 finding sealed sources. The basis for the estimates are calculations and 2s experiments. The details are being sought.
2s 10
Rough Draft September 5.1996 Comments 2
1.2.3 Steel Mills Information about the equipment in steel mills, the practices, and the 2
experiences will be collected through a survey of the mills. The equipment of 3
interest is the monitoring equipment, the vehicles used to transport scrap metal, e
the amount of scrap metal. The practices ofinterest were the decision criteria s
to accept shipments passing through radiation monitors and the action taken s
when a shipment is to be rejected. The experiences are the number of alarms 7
and rejections.
e Much of the concern with the nuclear gauges in the recycling stream is the cost 9
of smelting a sealed '37Cs or 6 Co source. Good information is available. This to portion of the model will be detailed.
it 1.2.4 Scrap Yards 12 A survey of the scrap yards to determine equipment, practices, and experiences 13 will not be done. The P1 had met with the Institute of Scrap recycling Industries 24 (ISRI) in Washington DC. The ISRI stafTexplained that the success of a sun ey is of the scrap steel industry is very questionable. ISRI would support a survey, 26 though such an effort would be a large undertaking; ISRI has 1600 members.
12 Likely the response rate of the members would be low-10% to 20% would e 28 a high response rate. More likely response rates would be near 5%. The 19 members will want to know what they will directly get out of a survey that will 2o benefit their businesses. The scrap metal business is very competitive; profit 21 margins are thin; markets are very fluid.
I 22 t
Then there is the issue of how representative the responses would be. What 23 could be determined from the data is of concern. What might be said, regardless 24 of the data, is a bigger concern.
2s Some questions that appear to be benign are not so. Monitoring is a sensitive 26 issue and has become a political football between the scrap dealers and the steel 27 mills. Suppose that a figure representing the fraction of scrap dealers having 28 monitors could be reliably determined. A low figure would cause a lot of 29 tension between the scrap dealers and the steel mill owners. Even if most of the 30 scrap metal goes through those monitors, the figure would still be contentious.
31 11
Rough Draft September 5.1996 Comments The problems of collecting infonnation through a survey virtually preclude a 1
2 successful effort:
A large effort yielding a low response rate 3
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Representativeness of the sample 4
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Perception of the outcome s
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ISRI has general information about the flow of scrap metal. This information s
will be used to construct a simple model of the scrap yards. The scrap yards will be treated as a conduit through which scrap metal passes on it way to the steel e
9 mkils.
Some information about the scrap yards directly supplying the mills will be to obtained from the survey of the mills. The mill staff will know which yards are it supplying them and might know about the monitoring equipment in the yards.
12 The extent to which this information can be obtained will vary from mill to mill.
n Some mills have only a few suppliers and the mills have insisted on radiation 14 monitors that are operated with standard procedures. Some mills obtain scrap is metal from as many as a hundred scrap yards through a broker and the suppliers is change according to market conditions. But at least some information about the 17 scrap yards immediately supplying the mills may be accessible.
is 1.2.5 Demolition and Salvage Contractors 19 If a survey of the scrap yards will yield scant results, a survey of demolition and 2o salvage contractors to learn about their practices and experiences with nuclear 21 gauges would be even less. These contractors are very entrepreneurial. A large 22 number of them are also very transient. The demolition and salvage business is 23 competitive; jobs are large problems of managing resources-it is doubtful that 24 25 records of use to the risk assessment exits.
Very general information about how demolition and salvage is done will be 2s obtained from site visits. During these visit, some semi-quantitative information 27 about the number of demolitions and renovations may be possible.
28 12
Rough Draft September 5.1996 Comments 1.2.6 Scrap Metal Collectors 1
Scavengers, gypsies, and peddlers are virtually unreachable, even to infbrm them 2
of the concerns about nuclear gauges in the recycling stream.
3 1.3 Scope of the Risk Assessment 4
The scope of the risk assessment are the pathways shown in Figure 1:
s Transfer to an industrial facility, such as when an industrial facility 6
receives a nuclear gauge but before the gauge is installed.
7 Transfers to an SLs and GLs.
8 IIansfers to a LLW site, such as when a nuclear gauge has reached its 9
semice life or a licensee is no longer able to give assurances of safely 10 possessing the gauge.
11 The following aspects of Figure 1 are beyond the scope of the risk assessment:
12 Controls on the construction of the nuclear gauges u
Markets for products and byproducts 14 Unauthorized use 2s Reclamation from landfill 2s Pathways of normal products 17 Landfill mining will not be modeled at first. Scrap metal is valuable; most of is il goes into the recycling stream and little of it is discarded into landfills.
19 Landfill mining is as yet a small industry, only now becoming economically 2o feasible. The following assumption is being made.
21 ifssumption: The major way that nuclear gauges enter the recycling 22 stream is by way ofthe processing ofscrap metal.
21 The paucity of data that can be obtained from the scrap yards will limit the 24 modeling of the scrap yards. Much of the information will be at the later stages 2s of the recycling stream, at the yards directly supplying the steel mills, at this 26 information will about the monitoring, not the equipment in the scrap yards.
27 The quantitative treatment of the scrap yards will be with sensitivity studies:
28
)
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Rough Draft September 5.1996 Comments No potential for detecting a sealed source 1
No potential for dislodging the source from its holder 2
Potential for dislodging a sealed source from its holder i
The pathway of scrap metal through the mills will be modeled in detail, even 4
though, at present, quantitative data about the scrap yards is lacking. The large s
economic consequences are at the steel mills. The pathways can be quantified.
6 The radiation monitors at the mills and, at least in scrap yards immediately 7
adjacent to the mills, will be modeled. A model accounting for the shielding of 8
the gauge, the bulk of the scrap metal, the detectors, and the electronics yields 9
the probability of detecting a sealed source. The operation of monitoring lo systems will be assessed through the survey of the mills.
u The processing of contaminated products and byproducts from a smelting will j
12 be accounted as the costs to decontaminate a mill, place it back into operation, n
and disposed of the contaminated products and byproducts.
14 Health effects will be measured in terms of curies of intact, dislodged, and 1s 16 breached scaled sources.
17 2 References is 1.
Personal communication 19 2.
Personal communication 20 3.
U.S. Code of' Federal Regulations, " Rules of General Applicability to Domestic Licensing of Byproduct Materials," Part 30, Chapter 1, Title 21 10, " Energy," U.S. Government Printing Office, Washington, D.C.
22 14
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