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Reference, Questions and Help => Nuke Q&A => Topic started by: Kernwerker on Aug 26, 2020, 12:35

Title: Radiation area or controlled area?
Post by: Kernwerker on Aug 26, 2020, 12:35

Hi guys,

It seems we have different phrases to describe an area that is under supervision of the Radiation protection law(whatever you call that in the States) and surveying occupational personnel that work in nuclear installations

For example:

Occupational personnel are devided into 2 main Groups. One is cathegory A with an annual dose limit of 20 mSV (20mRem) per year and cathegory B which has a limit of 3/10 of cathegory A so that amounts to a limit of 6 mSv per year

So in Germany a so called controlled area (in German "Kontrollbereich") would be taking the value of category B and devide that by 2000 hours so a controlled area in Germany would be an area that CAN have a doserate of > 6mSv  / 2000hours = 3µSv/h
And our high Radiation Areas or restricted Areas  would be Areas with doserates that CAN exceed 3mSv/h (300mRem/h)

We also have an area outside the controlled or Radiation area that we would ball "area und supervision" 'This area on the plant sight means that you could get dose >1mSv per year but no higher then 6mSv per year (6mRems)
And of Course outside the plant boundry or public land no higher then 1mSv/h

My question is what are the correct Phrases for the respective Areas in the States and what are there values?

Many Thanks in advance

Robert Wise
Senior RP-Technician in the NPP Philippsburg Germany

Title: Re: Radiation area or controlled area?
Post by: peteshonkwiler on Aug 26, 2020, 01:39

Unidentified radiological areas must be <57 microREM per hour, aka the hobo rule, based on an annual dose of 500 mREM.

Radiologically Controlled Areas would be > 57 microR/hr.

Radiation Area would be 5—<100 mR/hr @ 30 cm from a source surface.

High Radiation area would be 100—<1000 mR/hr @ 30 cm from a source surface.

Locked High Radiation area would be =>1000 mR/hr @ 30 cm from a source surface.

Very High Radiation Area (aka Grave Radiation Area) would be => 500 Rads/hr @ 1 Meter from a source surface.

Title: Re: Radiation area or controlled area?
Post by: Rennhack on Aug 26, 2020, 06:28

The US Department of Energy (10CFR835) and the US Nuclear Regulatory Commission (10CFR20) share many terms, but some are unique to each law.

10CFR835 Definitions: https://www.ecfr.gov/cgi-bin/text-idx?SID=c161bd970079918204d84d8490b3888c&mc=true&node=se10.4.835_12&rgn=div8
10CFR20 Definitions: https://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1003.html

Title: Re: Radiation area or controlled area?
Post by: Kernwerker on Aug 28, 2020, 03:28

thx alot guys for the answers to my post