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Participant

Join Date: Apr 2007
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Detecting Cobalt 60 in SS 316L

08/02/2009 4:03 AM

1) how to detect the presence of Cobalt60 in ss 316L.

2) we have analysed a sample of ss 316 L plate 12/13mm thk using spectrograph. this test shows presence of Cobalt as 0.065%. is the presence of Cobalt as mentioned acceptable, can the material be accepted as SS316L given that all other parameters are within the acceptable requirements of SS 316L.

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Guru

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#1

Re: Cobalt 60

08/02/2009 5:08 AM

The cobalt almost acts like Ni (so almost effectively increases the effect of it)

Being the trace elements may be acceptable at these light percentages.

Checked all our standards and found this in the trace element category but not the 316 (check whether there is a mention of it in that standard)

From the web

Cobalt

Cobalt becomes highly radioactive when exposed to the intense radiation of nuclear reactors, and as a result, any stainless steel that is in nuclear service will have a cobalt restriction, usually aproximately 0.2% maximum. This problem is emphasised because there is residual cobalt content in the nickel used in producing these steels.

(http://www.chasealloys.co.uk/steel/alloying-elements-in-steel/#cobalt)

However significan Co are supposed to be beneficial (increases fracture toughness in steels)

Wait for Milo to chip in.

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#3
In reply to #1

Re: Cobalt 60

08/02/2009 11:05 PM

Thanks for the introduction sb.

You have got a good start.

My primary concern is that the question specifies the Cobalt 60 which is a manmade isotope-RADIOACTIVE!!!- not merely cobalt.

THIS IS NOT A JOKE. SAFETY ISSUE HERE NOT CHEMISTRY!

The question really tells us that there is a concern about whether or not this stainless steel product is free of contamination by radioactive sources. COBALT 60 is a strong radioactive source of gamma rays. Used in mills for level control of hot metal in mold and tundish. (we had one on our caster in Johnstown, Not sure what the source was in our other mills)

Your spectrometer determined cobalt as the element, but did not identify the isotope.

Have you done a radiation survey of the material? looking for beta and strong gamma rays.

Analysis of metal is because of past accidents where radioactive sources contaminated the metal being processed. (where accidents= stolen for scrap value?)

We saw this bulletin via one of our european mills earlier this year:

http://www.spiegel.de/international/world/0,1518,607840,00.html

Your spectrometer anlaysis of cobalt shows that level to be residual or trace. You have not told us the specification controlling this purchase, we will report back in the morning regarding allowable residuals for natural Cobalt per UNS and ASTM.

These will be for natural, NOT RADIOACTIVE COBALT!.

The designation of Cobalt 60, like Strontium 90 is an important clue that health impacts due to radioactivity are the concern. (Strontium 90 is usually found in steel products coming out of former soviet union mills...)

Thanks for asking the question.

If you would like to discuss this persoanlly, drop me an email by clicking on my name above (its a link and I'll send you my phone number and we can speak privately about your concerns.)

milo

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#5
In reply to #3

Re: Cobalt 60

08/03/2009 3:40 AM

Hi,

there have been two unintended remeltings of scrapped Cobalt60 radiation "bombs" used in hospitals until service problems stopped the further use. Then stored for years with a lazy security staff- everybody forgot about the dangerous inside.

Then sold as scrap to remelt, then showing up in a much diluted but still unacceptable level in steel products.

First was in Mexico (see SciAm archivers for details), being detected as a truck triggered an alarm at leaving Los Alamos National Laboratory (a piece of its frame was made from the material),

the other one the recent find in Germany last year originating in India - many unexpected technical products contaminated to dangerous levels if in prolonged contact with persons. Fortunately no critical radiation levels known, removed products have been valves for chemical use and knobs for electric equipment. But the material has gone to other states too - it was detected first in a container scheduled from Mumbai to Russia at a stop-by in Hamburg Harbor, Germany.

Why is there no world-wide inventory and supervising authority for such a bad stuff?

RHABE

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#7
In reply to #3

Re: Cobalt 60

08/03/2009 6:20 AM

Hello Milo,

Hope all is well with you?

Exceptional post from you. I was going to deal with this and decided to read any posts already here. I am really interested in Radioactivity but, you got there before me!

GA to you Sir........................

Take care.........................

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#12
In reply to #3

Re: Cobalt 60

08/03/2009 9:47 AM

Missed the isotope (and that too the material being such a common for our own NDT area more sobs)

That't why the boss should chip in. Yes even at that minute concentration the Co-60 is dangerous. What you should try to find out is the radiations from it and that puts the limit as per the Nuclear Radiation Safety (OSHA) and other guidelines.

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#15
In reply to #12

Re: Cobalt 60

08/03/2009 10:54 AM

Thats ok. Thats why this forum rocks. There is wisdom amongst all of us , and like a team, we'll get there. everybody contributes toward the goal of getting the answer.

You're right, its a common Source material for Industrial applications.

milo

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#2

Re: Detecting Cobalt 60 in SS 316L

08/02/2009 10:52 PM

Also, with respect to new steel, natural cobalt is 100% Co59. Co60, with its 5.27 year half-life, would only need to be looked for if nefarious contamination is suspected.

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#37
In reply to #2

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 5:01 AM

Hello N&P,

=

I hopw you are well?

=

With respect, I cannot aggree with you on this.................

You say: "With respect to new steel, natural cobalt is 100% Co59. Co60, with its 5.27 year half-life, would only need to be looked for if nefarious contamination is suspected".

=

Look at like this............. If there was "nefarious contamination" which by its nature is not expected, and you did not test the steel, how would you ever know?

You may check for several months or a year or so, and then find contamination of the scrap. But you must check every time, not just when its raining, or you have an itch on your nose.

There must be a Rule that says, "'ALL STEEL', or 'ITEMS OF SCRAP' to go to make up a steel batch, must be tested before any in included in the melt"

After all, waste in general does get checked before being sent to a steel mill, or you could get rubber, glass and other unwanted metals in the mix and 'standards' would be nonsense!

If this testing is not 'ROUTINE', which means every single item gets scanned and or checked by eye, to look for certain 'shapes' of things which would often contain radioactive substances before melting down, (by which time it is too late) any test is useless under your rule.

It may well be that my testing by eye etc, cannot be done to every single piece but it should happen in my opinion.

Take care and no offence meant.

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#39
In reply to #37

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 8:20 AM

Actually, when one understands the process, then it becomes clear how to assure the steel is not contaminated.

At the melt shop, samples are taken of the initial batch of liquid steel (the "heat.") Those samples need to be prepared for analysis. at the first point where those samples enter the lab to be prepared, we put a geiger counter right above the first vise where we removed the stem (for leco carbon analysis) from the body (polished and analyzed on optical spectrometer.) We used a vacuum tube system for sample transport, but this could work even with manual hand carry systems. If the melt was contaminated by a radioactive material in the scrap stream, this is the point where we would detect it. Why test thousands of pounds of product when you can check the 180 ton melt with a single 4 oz lollipop sample?

Similarly, tundish samples from the caster also enter the lab the same way.

Once solidified, radiological contamination is not an issue.

As was mentioned in an earlier post, we also had radiation detectors/survey meters at the gates where rail cars entered the plant, and at the truck scales where all trucks passed through.

Inspection of product is seldom the "right answer" building in mistakeproof systems to verify that your process is working as we did is the way to assure quality conformance.

(If the issue is that somehow our own level control gamma ray source somehow fell into the bath, Believe me we'd know we'd have an issue by the breakout and spill of molten material...)

milo

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#40
In reply to #39

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 9:16 AM

Milo, I'd be willing to bet that most of the problem batches are from foreign mills with much looser QA/QC. I also would not be surprised if some of the gulf war tank hulks didn't get sold as scrap iron. between the DU contamination from the sabot rounds that killed em and the DU in the armor plate itself there'd probably be some uranium contamination. Not sure what the solubility of u-238 would be in steel...

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#41
In reply to #40

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 9:53 AM

Uranium is pyrophoric. It would combust/ vaporize in our melt shops in air. Remind me to wear a respirator if I ever have to supervise changing bags in baghouse again!

milo

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#42
In reply to #39

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 11:09 AM

Hello Milo,

I have never known the detailed way a steel company works, with Geiger counter on the gate, scales and other delivery points as well as near the melt itself.

I appreciate the way you have explained it, thanks.

As I tried to say there is several sorting methods used before any of the scrap ever gets close to a steel furnace. As you explained in so much detail I and others have a better idea of what exact happens from the delivery to the finished product. Thanks once again.

I have always been interested in the 'sort of magic' which goes to make a certain grade of steel, but on any films I saw they never mentioned the tests or the Geiger counters.

Take care my friend.

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#4

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 12:32 AM

Co 60 is a radioactive isotope of chromium and has no business being in SS 316L. It has a half life of about 63 months and is not found in nature. It is artificially made and used for medical sterilization.

What you found must be the normal nonradioactive Co. Since it is not specified Co at 0.065% should be acceptable.

bioramani

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#6

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 3:42 AM

Hello,

I think Milo's answer is quite clear.

Just to point that Co-60 (the sum of 27 protons and 33 neutrons) can come from industrial gammagraphy sources or activation of Co-59 (27 protons and 32 neutrons) absorbing a low energy neutron.

Cobalt is present in many NPPs as part of Stellite 6 widely used in valve seat hardfacing and becomes the main non desired source of Co-60.

The "activation" of Cr-52 (24 protons and 28 neutrons) or even Cr-54 (30 neutrons) to become Co-60 is strange to me. I find difficult to think a nuclear reaction which could add 3 protons and 3 or 5 neutrons to chromium.

Co-60 can be easily identified with any radioactivity detector by its activity (it dessintegrates giving two gamma rays with 1,17 and 1,33 MeV respectively)

Kind regards

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#13
In reply to #6

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 9:52 AM

Cr?

Co60 is usually result of irradiation of stable Co59 usually in nuclear reactors.

I went through google and there are a string of cases of Co60 contaminations and most are from the steels that are produced by remelting the ships.

The source and root-cause are obvious.

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#16
In reply to #13

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 1:13 PM

Hi sb,

Why are you obsessed answering my posts?

If you read carefully, I said Cr is not a common source answering a former post and give the reasons. I didn't google it because of 35 years working in the nuclear field.

Kind regards

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#22
In reply to #16

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 8:57 AM

hello Kwetz I am sorry but it was tagged to the wrong post.

However I was not aware that you resent getting your posts replied.

And my google was to find the incidences world wide of the contamination and the root cause.

BTW : I don't remember keeping on answering/ picking up on you. If you feel on that way I am sorry.

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#24
In reply to #22

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 9:14 AM

you could always say its a gremlin that did it...

Gotcha!

milo

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#34
In reply to #24

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 11:36 PM

You used the G word

Now you are only responsible for the Grroutcome (did something explode ?)

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#19
In reply to #6

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 10:40 PM

Hello Kwetz,

As I said in another post, I find it difficult to understand why the Authorities do not make a 'rule' that every waste metal dealer should have a machine to check for radio-active steel etc?

From what I have read there does seem to be a lot of possible sources of Cobalt-60. And I am not saying that the cobalt the OP has found is Cobalt-60, OK?

Interesting thread and subject!

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#20
In reply to #19

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 3:11 AM

Hi babybear,

I don't know every aspect of ruling in each country, but here in Spain (and in France where I'm just now in a NPP) is obligatory for all trucks leaving the plant to pass through rad detectors. Furthermore, in Spain is obligatory for all steel mills, foundries,... to do the same for incoming scrap. This rule comes from an incident some years ago in which a "spent" (for its intended use) source was melted and some tons of steel became radioactive..

Bear in mind that radiation dose coming from Co-60 is 50 times that of Ra (that element studied by Marie Curie) 1 gram of pure Co-60 can kill a person by a few minutes rad exposition.

So, even in small quantities Co-60 is rather dangerous.

Kind regards

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#21
In reply to #20

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 3:57 AM

Hello Kwetz,

I really appreciate your reply post, thank you.

I have not searched on this subject of all the potential machines and containers this Cobalt-60 may have been used in. I know of some in Hospitals and the food industry, but there is many more, hence my not searching, as there seems to be too many variables.

Do you know what happens to this 'spent' radioactive steel? On Cobalt-60 specifically I have read that it is supposedly 'safe' after 20 or 30 years of storage. In the mean time is not the radioactivity 'escaping' into the atmosphere and it is dangerous for many years. Though I understand it has a half-life of 5.27 years, which means there is little left after say 30 years?

I just want to make it clear that I do not and have not dealt in any kind of steel or metal whether radioactive or not! These questions are because of my interest in this subject.

In a hundred years the radioactivity reduces to 0.0051464%. Not much but, still it is radioactive!

I have also wondered if the still was stacked say in sheets and was contaminated with Cobalt-60, if there was say a block stacked together about 10 metres square. Would the Cobalt-60 in the centre of the block radiate, or should I say be clear (eventually), or would it take longer for this centred contrasted area to irradiate out?

This is for my own interest only. Thank you.

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#23
In reply to #21

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 9:05 AM

Generally speaking, a hold time of 10 half-lives is required for most radioactive elements to be considered "safe" however many radioactive elements (cobalt 60 not being one of them) decay into OTHER radioactive elements, so you have to take that into consideration too.

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#26
In reply to #23

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 4:04 PM

Hello Rorschach,

Thank you for your reply post, really appreciate it. That radioactive elements decay into other similarly nasty types hardly matters if the half-life is Millions of years, but is a PITA when there is one that has 'only' H/L of a few hundred years!

Thanks again my friend.

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#27
In reply to #26

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 4:26 PM

Don't get me started on this country's asinine policy concerning nuclear waste reprocessing. We could have a very nearly closed nuclear fuel cycle in this country with much smaller amounts of waste that would only be dangerous for a few hundred years vs hundreds of thousands, and gain 90% greater efficiency in the process. But NOOOOO! we have to stack the stuff like cordwood because you could use the same processes to extract plutonium and make bombs with it. Meanwhile the only reactor in North America that is capable of making Molybdenum 99, from which Technetium 99m is derived, is in Canada (because again reprocessing nuclear products in this country is illegal) and it is old and has been shut down yet again for safety problems/leaks and might not be restarted. Technetium 99m is vital for cardiac perfusion studies and bone cancer scans and kidney diagnostics and has a half life of only 6 hours so obtaining it from Europe or South Africa is not possible, and stockpiling it is not possible either.

Let us hope that none of us here in North America have a heart attack and need to have a nuclear cardiac perfusion study done, because it just ain't happening.

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#28
In reply to #27

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 4:33 PM

So why not start out this topic as a separate thread?

GA by the way.

milo

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#29
In reply to #28

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 4:39 PM

Good point Milo, it probably should be another thread, I'm just so freaking frustrated with this country's asinine policies in this regard that I tend to lose it once in a while.

Excuse me while I go do some deep breathing to regain some semblance of control....=b

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#30
In reply to #27

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 5:21 PM

Hello Rorschach,

This sounds really odd. It must be obvious this radioactive substance with a H/L of just a few hours, is for Medical use?

Take care..............

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#32
In reply to #30

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 5:34 PM

Exactly babybear, it is used to track blood flow in both kidney and heart scans, it is used to detect new bone growth for bone cancer scans (concentrations of new bone growth indicate tumors), and it is used to localize and identify the locations of lymph nodes to be removed during mastectomies. It is almost perfect in this regard because it is a gamma emitter and is therefore detectable outside the body, it and it's stable decay product are not terribly toxic, and it has such a short half life that the patient does not get a very high dose of radiation in the process.

I posted about this on another thread here.

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#31
In reply to #27

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 5:23 PM

Hello Rorschach,

GA for you Sir

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#36
In reply to #27

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 2:51 AM

The Pu extracted from most commercial reactors is too polluted with various non-fissile isotopes of Pu to be readily processed to "weapons grade", as distinct from the much lower requirements of "reactor grade".

This seems to be unknown to the green and anti-nuclear people, who seem to claim that all Pu is fissile and hence a source of nuclear weapons.

If they were really worried about nuclear proliferation, they would want reprocessing because the safest place for Pu is in a reactor - both from a proliferation and an environmental perspective.

In fact, for a reactor to be used for weapons grade Pu production, it must be run a special way. The fuel must be extracted for processing long before it is economically justified and contains a considerable mount of "unburnt" fissile material.

Your comment on Technetium 99 is especially relevant to me. A few years ago I had a Technetium scan. The material was flown up from the Lucas Heights reactor in Sydney (about a 3 hr flight), where we have a heavy water (Candu type) reactor which is ideal for making medical isotopes (also ideal for fissile Pu production if we were so inclined).

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#25
In reply to #21

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 9:15 AM

Thank you babybear,

What happens...?

As with any radioactive material it decays according to its own half-life. In the case of Co-60, as you say the half-life is about 5,27 years. But that means any Co-60 mass will be reduced to one half in 5,27 years, and to a quarter in 10,54 years and so on, so after 100 years the percentage of initial material is less than 0,0002%.

The possible amount in a believable case of steel contamination after 100 years will have no dangerous effects.

And think also that the radiation dose absorbed from any source diminish in a ratio inverse to the square of the distance to the source. That means, if at 1 meter you get a dose of say.. 1 mSv, at 10 meters you'll get just 0,0001 mSv.

Also think that matter interferes with radiation and therefore, steel (not contaminated) is a good shield against radiation. A couple centimetres reduces any Co-60 dose to one half too.

Kind regards

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#33
In reply to #25

Re: Detecting Cobalt 60 in SS 316L

08/04/2009 8:28 PM

Hello Kwetz,

Thank you for the detailed explanation my friend. I had read of the inverse square but forgotten it! Your time in doing this is very much appreciated.

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#35
In reply to #25

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 2:15 AM

Co60 is a favorite source for radiographic examination of steel because it emits particularly strong gamma rays, which need quite a lot of steel to absorb them.

We were satisfactorily exposing photographic film through 2x 1/2" thick layers of steel.

The beta particles are quite easily absorbed, but not the gamma.

As someone else mentioned, the first move is to check the steel with a Geiger Counter.

If radiation not significantly above background then no problem.

If it is, steel is potentially dangerous and should be either disposed of or quarantined for some years until the radioactivity has settled to an acceptable level.

If you cover the stainless steel with a thin sheet of non radioactive steel 9Or even Al foil) and test again, you will find out if the radioactivity is due to Co60 or not. Co60 will still give a significant reading whereas alpha and gamma ray sources (most sources of contamination) will give virtually no reading above background.

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#38
In reply to #35

Re: Detecting Cobalt 60 in SS 316L

08/05/2009 5:50 AM

Hi sceptic,

You're right, but as some of us have said, the energies associated with Co-60 disintegration are 1,17 and 1,33 MeV which are really hard ones. So Co-60 is not well suited for radiography of steel under 20 mm thick.

Anyway, steel can act as a shield even is not the best material (lead is preferred). In fact 30 mm of steel reduces the dose to one half, the same as 13 mm of Pb.

Kind regards

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#8

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 6:42 AM

Hello shreep,

With reference to the contamination of this and other possible batches of steel:

From a personal point of view I would have said this metal was not fit for use at all. What remains is to wonder how the contamination happened? Can you shed any light on that, and possible ways you know of? Did the steel come from a supplier or do you make it?

Can you tell me exactly what Isotope it is as it makes a difference as to the radiation danger. It might be only .065%, but even at this level, approximately '1 in 1600'

there should be in my opinion a full investigation into how this was contaminated and, the exact route, including storage and vehicles used to move it. I sincerely hope none of this 'batch' is anywhere is can continue to contaminate people and places?

With such a small amount of Cobalt60 in it, it seems it was assumed this can be used.............. Maybe? ...............But if there was a spec of this Cobalt60 in some steel where a person was able to be contaminated day in day out, the risk is too great.

That person would not know. The fitters using this steel would not know and presumably the manufacturers of this steel did not know? ...........

.................. "JUST TOO MANY "IFS!"

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#14
In reply to #8

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 10:48 AM

babybear, you have jumped to too many conclusions.

The OP is trying to determine if material meets spec.

He has quantified presence of cobalt.

He has not qualified the isotopic nature of the cobalt.

There is no basis for the statement that "the metal was not fit for use at all."

The presumption that a 'contamination happened," denies the reality of residual elements in the scrap recycling process.

The probability of 1 in 1600 is irrelevant. Either this material emits Beta and Gamma radiation, or it does not. When its the center column of the table that every person in town sits down to in a restaurant and bathes their genital area in high energy emissions, the 0.065% by weight is no comfort nor defense.

Your links to the EPA site should be helpful to the OP and anyone else following this thread.

I do not find enough facts presented in this thread to make any conclusion, and would urge all of us to save the conclusions for when we have sufficent facts to make them.

The initial question is does 0.065% cobalt content cause the material to be rejectable. Per UNS entry for S31603 (316 L's "big boy name") There are no callouts for residual elements specified.

Per ASTM A 276, TAble 1, there are no specified nor footnoted limits for cobalt as a residual in this grade. The required conformance to AST A 484, does bring in ASTM A 484's paragraph 6.3 : " The steel shall not contain an uinspecified element for the ordered grade to the extent that the the steel conforms to the requirements of another grade..."

That is not the case at 0.065wt % cobalt.

milo "no basis for rejection at this time, pending radiological test for beta and gamma emissions."

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#17
In reply to #14

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 1:39 PM

I just for the "off record" checked up the materials we are recieving. None of our standards call for Co percentage check. Nore they are reported in the TC (except in a few cases where the spectro report is enclosed). All these are covered under we call "all the unspecified residual elements should not cross...%)". The specified are C,Si,Mn,Ni,Cr,Mo,V,S,P,Cu,Sn,Sb,As,Al,N,H... But never Co.

I checked the net and found the places where the Co60 was found was just by chance. The inspector went around to check the radioactivity and got the beep and then on cross check only the Co60 was found.

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#18
In reply to #14

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 10:11 PM

Hello Milo,

I did reread the OP's post a few times as I was researching, and yes did make a mistake when I read he had a contamination issue. I apologise to all for that, but I also wrote and thought I had sent a post to remedy my mistake. I have no idea where it went.

I did point out though this:

With such a small amount of Cobalt60 in it, it seems it was assumed this can be used.............. Maybe? ...............But if there was a spec of this Cobalt60 in some steel where a person was able to be contaminated day in day out, the risk is too great.

This was taken directly from the site below.

I find it difficult to understand why any second hand or scrap dealer is not required to test all the metal he deals with?

The site I went to first was:

http://www.epa.gov/rpdweb00/radionuclides/cobalt.html#properties

(Below is a quote from the site. Not one I agree with I have to say. But I made that clear.)

"How does cobalt-60 change in the environment"?

"Cobalt-60 undergoes radioactive decay with the emission of beta particles and strong gamma radiation. It ultimately decays to non radioactive nickel. The half-life of cobalt-60 is 5.27 years. This is short enough to make isolation a useful treatment strategy for contaminated areas. In some cases, simply waiting 10 to 20 years allows for sufficient decay to make the site acceptable for use again".

=

I am frustrated I did not check (as I usually do), that my post to try and rectify my mistake was not posted. I know there should have been three posts roughly the same size. On the site is only two posts.

Check your PM for a note on this sentence, thank you.

I appreciate your post to me Milo, thank you. (I am not trying to say it did, but I may have read into your post with all the warning 'signs' subliminally? Seeing the signs as confirmation rather than a warning?!

Did you actually talk further to the OP on PM and find out anything? Or perhaps I should not ask?

I hope this thread does not mean there is contamination. Makes me worry about the 'Authorities' and any rules and regs there is that these possibly contaminated steels from all kinds of sources should not be allowed to be part of the everyday steels! The quote I have entered above "How does Cobalt-60 change in the environment", seems to be bad news for any possible control of contaminated items whatsoever? Pretty worrying I would say.

=

Take care my friend.

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#9

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 8:21 AM

Hello shreep,

Further to my last post................

As well as the search page and one of the site address' I have pasted some comparatively small amount of info' from the site:

http://www.epa.gov/rpdweb00/radionuclides/cobalt.html#properties

The first list is the search page which has some great sites.

================================================

The detector search site is on the next post from me.

================================================

http://www.google.com/search?client=safari&rls=en-gb&q=http://www.epa.gov/rpdweb00/radionuclides/cobalt.html%23properties&ie=UTF-8&oe=UTF-8

The site below is a site which has a lot of details of Cobalt60

http://www.epa.gov/rpdweb00/radionuclides/cobalt.html#properties

The 'Half-Life' of Cobalt60 is 5.27 years

This means your test piece of cobalt60, if it is Cobalt60, will need to have been in store for around 35 years to get down to 0.04117 %. So yours has been in storage, or the steel used to make your batch was in storage before making the steel for 33 years ± one year.

To put this into perspective "Uranium" has a 'half-life of around 4.5 million years!

What can I do to protect myself and my family from cobalt-60? What is EPA doing about cobalt-60?This present post gives some very detailed info' on "Cobalt60". I urge you to go to this site below and read more.

================================================

Cobalt

Reference Information

People and Discoveries

Commonly Encountered Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Cobalt (chemical symbol Co) is a metal that may be stable (non radioactive, as found in nature), or unstable (radioactive, man-made).

=============================================

The most common radioactive isotope of cobalt is

....... Cobalt-60

.......

=============================================

On this page:

The Basics

Who discovered cobalt and cobalt-60?

Where do cobalt and cobalt-60 come from?

What are the properties of cobalt-60?

What is cobalt-60 used for?

Exposure to Cobalt-60

How does cobalt-60 get into the environment?

How does cobalt-60 change in the environment?

How do people come in contact with cobalt-60?

How does cobalt-60 get into the body?

What does cobalt-60 do once it gets into the body?

Health Effects of Cobalt-60

How can cobalt-60 affect people's health?

Is there a medical test to determine exposure to cobalt-60?

Protecting People From Cobalt

How do I know if I'm near cobalt-60? What is cobalt-60 used for?

Cobalt-60 is used in many common industrial applications, such as in leveling devices and thickness gauges, and in radiotherapy in hospitals. Large sources of cobalt-60 are increasingly used for sterilization of spices and certain foods. The powerful gamma rays kill bacteria and other pathogens, without damaging the product. After the radiation ceases, the product is not left radioactive. This process is sometimes called "cold pasteurization."

Cobalt-60 is also used for industrial radiography, a process similar to an x-ray, to detect structural flaws in metal parts. One of its uses is in a medical device for the precise treatment of otherwise inoperable deformities of blood vessels and brain tumours. Radionuclides, such as cobalt-60, that are used in industry or medical treatment are encased in shielded metal containers or housings, and are referred to as radiation 'sources.' The shielding keeps operators from being exposed to the strong radiation.

Exposure to Cobalt-60

How does cobalt-60 get into the environment?

Occasionally, medical or industrial radiation sources are lost or stolen. We call these "orphan sources." They pose a significant risk:

On a number of occasions, people have handled them, not knowing what they were, and have been exposed.

Sometimes sources find their way into municipal landfills, where it is illegal to dispose of them.

Because of their metallic housings, sources can get mixed in with scrap metal and pass undetected into scrap metal recycling facilities. If melted in a mill, they can contaminate the entire batch of metal and the larger facility, costing millions of dollars in lost productivity and cleanup costs. The scrap industry uses radiation detectors to screen incoming material. However, sources that are under large loads may be undetected initially.

Cobalt-60 can also be released to the environment through leaks or spills at nuclear power plants, and in solid waste originating from nuclear power plants. Nuclear Regulatory Commission regulations allow small amounts of cobalt-60 to be released into the air, or poured down drains as part of a liquid.

How does cobalt-60 change in the environment?

Cobalt-60 undergoes radioactive decay with the emission of beta particles and strong gamma radiation. It ultimately decays to non radioactive nickel. The half-life of cobalt-60 is 5.27 years. This is short enough to make isolation a useful treatment strategy for contaminated areas. In some cases, simply waiting 10 to 20 years allows for sufficient decay to make the site acceptable for use again.

How do people come in contact with cobalt-60?

Most exposure to cobalt-60 takes place intentionally during medical tests and treatments. Such exposures are carefully controlled to avoid the adverse health impacts and to maximize the benefits of medical care. Accidental exposures may occur as the result of loss or improper disposal of medical and industrial radiation sources. Though relatively rare, exposure has also occurred by accidental mishandling of a source at a metal recycling facility or steel mill.

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#10

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 8:42 AM

Hello shreep,

Metal Detector UK www.regton.com

Over 70 detectors in our shop Hobby & Security metal detectors

Carbon Monoxide Detectors www.BHL.co.uk/COAlarms

CO Detectors and Alarms Low Prices Mains & Battery. Free Fast Delivery Google Checkout Search Results

Activation analysis of Co-60 encapsulated in stainless steel needles Long source-detector distance (d = 84 cm) has been chosen to approach .... Gamma Spectrum ol Irradiated Co-60 Needle and of free Stainless Steel Needle .... radiometric purity of cobalt need]es encapsulated in stainless steel sheet ...

www.springerlink.com/index/X821GU67822L0L4V.pdf

- Similar - by E Hallaba - 1970 - Related articles - All 3 versions Container inspection system using cobalt-60 γ-ray source and ... Plus the value of the detector, the total cost for the inspection system using .... The γ-rays emitted from the cobalt-60 source arecollimated to be a sheet form .... the container truck is towed by steel cable of a hoist 13 and moved ...

www.patentstorm.us/patents/7082186/description.html

- Similar -

================================================

Cobalt 60 contamination in Stainless Steel

6 posts - 5 authors - Last post: 30 Apr I did a Google search on "Cobalt 60 Stainless Steel Contamination India" and ... Reason: Add link to material safety data sheet ... The size of the GM detector in the Gamma Scout is quite small, thus its ability to see ... elsmar.com/Forums/showthread.php?t=33312 - Cached - Similar - Container inspection system using cobalt-60 γ-ray source and ... 25 Jul 2006 ... The defects when using gas detector are as follows: The detection ... In the container inspection equipment with cobalt-60 γ-ray ..... mm placed behind a steel sheet with thickness 100 mm, that is, IQI=2.5%, CI=0.7%;; 2. ...

www.freepatentsonline.com/7082186.html

- Similar -

by J Zhao - 2006 - All 7 versions

The World of Physics - Google Books Result

by John Avison - 1999 - Science - 504 pages

The radioisotope cobalt-60 is used to check welds in steel structures and pipelines. ... A radiation detector on the other side of the sheet measures the ...

books.google.com/books?isbn=0174387334... -

National Safety Council Radiation

Control the thickness of sheet products, such as steel, aluminum foil, paper, .... The cobalt-60 in an irradiator is contained in stainless steel capsules and ... By ionizing the air sealed inside the detector, the radiation produces an ...

www.nsc.org/resources/issues/rad/usage.aspx

- Cached - Similar -

[PDF] accidents fact sheet - US File Format: PDF/Adobe Acrobat - View entered the irradiation chamber at a cobalt-60 facility near San Salvador. ... A Food Irradiation. Fact Sheet ... ordered to wear their radiation-detection — badges" in ... clean-up, nearly 50 tons of steel, 250 cubic feet of ...po[ www.citizen.org/documents/accidentsfactsheet.pdf

- Similar -

Surface conditioning by reactive gases during continuous annealing ... Applying very strong carburizing treatments with carburizing times of 60 s, ... The carburizing treatment was set up by purging a reactive CO–H2–N2 atmosphere ... carbon concentration range, the detection limit for carbon is 2 mass ppm [2] . .... J.-F. Willem, J. Crahay, V. Leroy, Developments of new sheet steel by ...

linkinghub.elsevier.com/retrieve/pii/S0924013601007786

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Spectrum of the radiation from a cobalt 60 teletherapy unit a cobalt 60 therapy unit of 1000 c or more will ... the intensity of the beam which falls on the detector. .... STEEL. JooQ^fP. C O B A I .... three times that of the Lucite sheet subsequently used (-j^ in.), the shapes of the spectra ...

bjr.birjournals.org/cgi/reprint/36/427/514.pdf

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================================================

by JW Scrimger - 1963 - Cited by 3 - Related articles - All 3 versions Searches related to: cobalt 60 detector for sheet steel cobalt 60 radiation

================================================

=

[PDF] Radiological Dispersal Device (RDD)

File Format: PDF/Adobe Acrobat - View as HTML of stainless steel, titanium, platinum, or other metal, and gamma emitters are encased in dense ... (Co-60, Ir-192). Food product sterilization (Co-60). Smoke detector ..... This fact sheet is intended to help support that objective. ... www.ead.anl.gov/pub/doc/rdd.pdf

- Similar -

=

I hope some of these are helpful. bb

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#11

Re: Detecting Cobalt 60 in SS 316L

08/03/2009 9:45 AM

Run a Geiger counter over it, if you get high readings then the answer is clearly no, it is not acceptable.

Cobalt is a very common "contaminant" to Nickel and very hard to separate from it because chemically they are so similar. Cobalt contamination is not a problem as long as it is not cobalt 60, which your radiation survey should be able to eliminate as a possibility.

And to whoever it was that said Co60 was neutron activation product of Chromium, sorry, you are very wrong. It is a neutron activation product of Co 59. it then beta decays to metastable Ni 60 which releases Gamma radiation before becoming stable.

http://en.wikipedia.org/wiki/Cobalt-60

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