NORM Decontamination Methods for Equipment in Qatar

The answer first

If a piece of oil or gas equipment is contaminated with NORM and you want it cleaned, article 11 of the rules attached to Decision 45 of 2013 sets four things. The work must be done by specialist persons. All necessary measures and precautions must be taken to protect workers from radiation when carrying out this work. The method must be one of those listed in Annex 2, and that annex names seven. And one method has priority: pressurised water in a closed circuit, with ventilation connected to filters to contain the radioactive solids.

Five words first. NORM is naturally occurring radioactive material, which the rules define as material in which the concentration of radionuclides rises because of what people do to it. Decontamination has its own definition here: reducing radioactive material and removing it entirely from the surfaces of equipment, persons and the environment. Scale is the hard crust that forms inside pipes and production equipment. Sludge is the soft solid that gathers in separators and tanks. Equipment is defined broadly: the materials and devices used in the oil and gas industry, or in the activities referred to in article 3 of these rules, such as containers, pipes, tanks and the like.

Note what the article is about before you read further: its subject is contaminated equipment. That is the wording, and it is narrower than everything on a site that might be dirty.

Article 11, line by line

The duty comes first and it is unconditional in form: decontamination of equipment contaminated with NORM must be carried out by specialist persons. There is no threshold in the sentence, no size of job, no exception for a small part. The qualification attaches to the work itself.

Then the article says the choice of method depends on several factors, and names three: the availability of the means to do the work, the cost of carrying out such operations, and the value of the equipment that will be cleaned. Read that opening carefully: the clause introduces these three as factors among others, so the list is open and they are examples, not a closed set.

Then comes the worker clause, and it is the broadest sentence in the article: all necessary measures and precautions must be taken to protect workers from radiation when carrying out this work. It names no measure. It does not say respirator, suit, dosimeter or time limit. It sets an obligation and leaves the content of it to you and to whatever other instruments apply.

Finally the method sentence: removal is by one of the methods specified in Annex 2, with priority to the pressurised water method in a closed circuit, and with ventilation connected to filters to contain the radioactive solids. Three requirements are packed in there. Closed circuit, so the water does not leave. Ventilation. And filters on that ventilation, with a stated job: containing the radioactive solids.

One wording difference is worth recording rather than smoothing over. Article 11 calls the priority method the pressurised water method in a closed circuit. Annex 2 lists a method it calls cleaning with water under pressure, with the abbreviation HPWJ. The two names are not identical, and the annex entry does not itself mention a closed circuit. We record the difference. We do not say the decision made an error, and we do not say the priority is written onto the annex entry by name. The annex entry also carries the words very high at a point where the sentence is disordered; we carry it as it stands and do not call it an error.

What article 11 does not reach

Its subject is contaminated equipment, by its wording, and equipment is itself a defined term in article 1. It is not written about a vehicle; vehicle is a separate term in the decision, and its definition is not part of what we have seen. It is not written about the outside surface of a waste container either: that has its own clause in the container article, which asks that surface contamination be measured on each container and, above 4 becquerel per square centimetre from beta and gamma, that the outer surface be washed with pressurised water until it falls below that figure. The becquerel is a unit of activity, one disintegration a second.

So there are two pressurised-water washes in this decision, in two articles, for two purposes, with two triggers. The container wash has a number that starts it and a number that ends it, 4 becquerel per square centimetre in both places. The equipment decontamination has no number at all: no trigger figure and no finishing figure. We do not say they are the same limit, and the decision does not refer the container wash to article 11. Where a container wash raises the same practical hazards, we treat the equipment guidance as something to learn from, not as something that binds.

Three more silences. The article sets no cleanliness target, so it does not say when a cleaned item counts as clean. The route to that answer runs through the exemption levels of Annex 1 and the sampling clause, and reading it that way is our reading, not a cross-reference the article makes. It sets no approval step for the method you pick. And in what we have seen of this decision, there is no penalty word and no deadline attached to this article.

The seven methods of Annex 2

Annex 2 lists seven methods and puts a short note against each. The table below sets out the annex entries one by one, so you can see what the decision provides for each method before any vendor describes it to you.

Choosing a method without guessing

Start from the priority, not from the catalogue. The article puts closed-circuit pressurised water first, so your default is that method. We recommend writing the choice down against the factors the article names. The article does not require that record and names no one to read it; the recommendation is ours, not a requirement of the article.

Then settle three things before anything is sprayed or scraped. Where the water goes, since a closed circuit is an infrastructure decision and not a nozzle. Where the removed solids go, since they are waste and re-enter the container and storage articles. And who the specialist persons are, with their qualification recorded before the job, not after it.

Questions we are actually asked

Technical note

Pressurised water is the priority method and also the one with the sharpest hazards, so name them. A jet on a crusted surface produces inhalable spray, and that spray carries whatever the crust carried. The water that returns is contaminated water, and in a closed circuit it keeps returning and keeps concentrating, which is a reason to filter it and not a reason to open the circuit. Dry scraping and dry vacuuming raise dust instead, which is why the annex keeps the drilling method wet and asks that its water be filtered. Chemical cleaning changes the shape of the hazard rather than its size: the annex describes it as using chemicals to dissolve hard deposits, and dissolving moves the radium out of a fixed crust and into a liquid that spreads, spills and gets discharged, so the question becomes where the liquid goes and not how much came off the surface. The chemical hazard to the workers sits on top of that. This decision gives no figure for such a liquid, so far as we have seen, and we will not invent one.

On measurement after the work, four cautions. First, a wet surface hides alpha: alpha particles are stopped by a film of water and by remaining crust, so a reading taken before drying can read low for the wrong reason. Second, which figure you compare against depends on which emitter you are dealing with, and the equipment row of Annex 1 gives two separate exemption figures that must not be exceeded, 0.37 becquerel per square centimetre for alpha sources and 3.7 becquerel per square centimetre for beta sources, so the emitter has to be named before a reading means anything. Third, a surface reading on the outside tells you little about the inside of a pipe, which is exactly where scale sits.

Fourth, background sits at both ends. The door into this article is article 6, which treats equipment as contaminated when the dose at its surface is more than twice the radiation background in the State, and no figure for that background appears in what we have seen. The background is the activity arising from natural cosmic and terrestrial sources. The dose figure in the Annex 1 equipment row, 0.5 microsievert per hour, is stated as including background at any accessible point. The microsievert is a small unit of dose, and per hour makes it a rate. The two becquerel per square centimetre figures in the row carry no such wording, and in a surface-contamination measurement background is subtracted rather than counted in. So on the dose route both the entry end and the exit end hang on a background with no published figure. This is a matter of measurement, not of wording.

And a word on who does this. The jetting, the filtering, the post-work survey and the record are the work of the specialist persons appointed for the job and of whoever is appointed to survey at the site. This is what we train people to do; it is not work we carry out.

How DITEC helps, and where its work stops

Most of the questions that reach us about this article are about the closed circuit and about where the removed solids go, not about which brush to use. We train on reading article 11 and Annex 2 together, and advise on the procedure and the records around a decontamination job.

ALDuha Institute for Training and Environmental Consulting (DITEC) works in training and consulting. The Institute does not run a laboratory analysis service, does not calibrate instruments, and does not test equipment. Field survey work is arranged through specialist partners.

Our training is licensed. Nothing here is an undertaking that a licence will be issued, and nothing here promises how long any application takes. The decision rests with the Ministry of Environment and Climate Change, Radiation Protection Department.

Reference: DITEC Experts and the Radiation Protection team. This page is an introductory explanation of a published decision and is not a legal opinion.