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Re: Maximum quantity(grams)per year of uranyl acetate to exempt from radioactive license
At 09:48 AM 2/27/97 -0600, you wrote:
>Dear radsafers
>
>I would like to receive suggestions on how to deal with our electronic
>
>microscope laboratory workers:
>
>1- The electronic microscope is exempt of radioactive control in Israel.
>
>2- The uranyl acetate that is used with the microscope is considered
>
> radioactive( 0.17 microcurie per gram).
>
>3- The maximum amount used per year in our laboratory is 12 g.
>
>
>Is it necessary to ask for a license to use this material?
>
>What is the ALI for uranyl acetate?
>
>Are there any long radiation effects for such annual quantity?
>
>What arguments can I use to convince the lab. workers that there is no
>danger at all whit such quantities?
>
>Thanking you in advance
>
>Sergio
>
>
>
> =============================================================================
> Sergio Faermann Ph.D. Tel: 972 - 7 -6 400682/6403301
> Chief Medical Physicist Fax: 972 - 7 -6 232336
> Institute of Oncology E-mail: sergio@bgumail.bgu.ac.il
> Soroka Medical Center
> P.O.B 151 Beer-Sheva 84101
> ISRAEL
> =============================================================================
Dear Sergio, going step by step on your questions:
1 - "The uranyl acetate that is used with the microscope is considered
radioactive( 0.17 microcurie per gram)."
1.1 -- HISTORY: Understanding the value 2 nanocurie/g and < 0.1 uCi
"The most natural objects contain some radioactive material, it is clear
that the provisions of the Manual (*) are not intended to apply below a
certain limiting degree of radioactivity. This lower limit can be taken as
a concentration of 0.002 microcuries per gram of material, or a total
activity in the working area less than 0.1 microcuries. These limits are
based on the most dangerous radioisotopes so that the use of somewhat higher
limiting levels of activity is permissible provided the isotopes present are
not the most dangerous"
(*) Safe Handling of Radioisotopes, Safety Series n# 1, IAEA, 1958
1.1 -- GO TO the Safety Series n#6, Regulations for the Safe Transport of
Radioactive Material, IAEA, 1985, (As amended 1990), page 9
139 . Radioactive material shall mean any material having a specific
activity greater than 70 kBq/kg (2 nCi/g)
This was the reason why several countries, including Brazil adopted the
above concentration as reference for radioactive material.
1.2 -- GO TO the Commission of the European Communities CEC- Community
Radiation Protection Legislation, August 1992, Title II, Scope, Reporting
and Authorization, article 4:
"Without prejudice to Article 5, these requirements for reporting and
obtaining prior authorization need not to be applied to activities involving:
(b) radioactive substances of concentration of less than 100 Bq/g (0.0027
uCi/g), this being increased to 500 Bq/g (0.014 uCi/g) for solid natural
radioactive substances"
-- Since the uranyl acetate used with the microscope has 0.17 uCi/g this
value is higher than the value above mentioned, so it is considered
radioactive substance.
2-- EXEMPTION CRITERIA:
By the other hand, you inform that: "The electronic microscope is exempt
of radioactive control in Israel."
2.1 -- GO TO Basic Safety Standard IAEA - I-115, Schedule I, page 81 --
Exemption Criteria:
I -3 - "A practice or a source within a practice may be exempted without
further consideration provided that the following criteria are met in all
feasible situations:
a) the effective dose expected to be incurred by any member of the public
due the exempted practice or source is of the order of 10 uSv or less in a
year and
b) either the collective effective dose committed by one year of
performance of the practice is no more than about 1 man.Sv or an assessment
for the optimization of protection shows that exemption is the optimum option.
2.2 -- Probably (you can check) the Competent Authority in Israel used the
above statement to exempt the practice or source. Nevertheless the I-115 is
new 1994, the above criterion is not. I, myself, worked in a Consultant
Meeting for the IAEA elaboration of "Code of Practice on Regulatory Control
of Consumer Products Containing Radioactive Substances, 1990, and we
approved the above value (** GO TO 6 (c))
Another consideration to the above assumption for the exemption in this
practice is that U NAT has very low radiotoxicity. The major concern of
natural uranium is only chemical.
3 -- "Is it necessary to ask for a license to use this material?"
Look, if you inform that the "The electronic microscope is exempt of
radioactive control in Israel.", There is no sense a license. There is no
sense a license, even if the practice wasn't exempted. Licensing for
Competent Authority is very rigorous while Registration is less rigorous
than licensing. However, if you have any doubt you should officially, by
letter or e mail, ask to the competent authority in Israel a clarification.
4- "The maximum amount used per year in our laboratory is 12 g."
-- If your intention is the comparison with the dose limits, or in your case
with exemption values, anyhow considering both cases to demonstrate to the
people involved the dose levels, the best you can do is to prepare a
scenario considering the works' condition. For demonstrating compliance with
dose limits, the sum of personal dose equivalent from external exposure to
penetrating radiation in the specified period and the committed equivalent
dose or committed effective dose, as appropriate, from intakes of
radioactive substances in the same period shall be used. For this purpose,
GO TO BSS page 93 II-12
4 -What is the ALI for uranyl acetate?
GO TO ICRP 61 Volume 21, N#4, page 37 for ALI
GO TO TABLE II-IV, page 223 and you can find directly the Committed
effective dose per unit of intake via inhalation for members of the public,
in Sv/Bq
GO TO TABLE II-V, page 301, and you can find directly the Committed
effective dose per unit of intake via inhalation for workers, in Sv/Bq
5 -- "Are there any long radiation effects for such annual quantity?"
Take your own conclusion after the above guidance
6 -- "What arguments can I use to convince the lab. workers that there is no
danger at all whith such quantities?"
a) Officially ask a confirmation from the Competent Authority about the
exemption as you mention;
b) Show risk consequences beginning with the scenario in the routinely work
and in case of an abnormal situation.
c) RSO should explain the meaning of risk to those directly or indirectly
involved in activities of ionizing radiation, clarifying doubts, using
simple words and examples.
GO TO IAEA Safety Series # 89 - Principles for the Exemption of Radiation
Sources and Practices from Regulatory Control, 1988, 4.2 to 5.3, page
8-11
7 -- "Thanking you in advance"
Not at all
Sergio, why you didn't send these questions directly to me? -- as you can
see, the two bibles ICRP and BSS can answer almost all the questions on
radiation protection. God made only 10 laws because he knew the man was very
complicated. However, even God didn't know as complicated the man was. Now
there are thousands of documents to explain those 10 laws. Conclusion: No
one knows more the meaning of the laws!
J. J. Rozental,
Consultant, Radiation Safety & Regulation
for developing country