Information Notice 1992-34, New Exposure Limits for Airborne Uranium and Thorium

New Exposure Limits for Airborne Uranium and Thorium

ML031200371
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	05/06/1992
From:	Office of Nuclear Material Safety and Safeguards
To:
References
IN-92-034, NUDOCS 9204300066
Download: ML031200371 (3)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

'OFFICE

- OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 May 6, 1992

92 MAY 26 P2:26 NRC INFORMATION NOTICE No. 92-34: NEW EXPOSURE LIMITS FOR AIRBORNE URANIUM

AND THORIUM

Addressees

All licensees whose operations can cause airborne concentrations of uranium

and thorium.

Purpose

The U.S. Nuclear Regulatory Commission is issuing this information

notice to alert addressees of changes, in 10 CFR Part 20, governing airborne

uranium and thorium exposures that may significantly affect exposure

calculations and reporting requirements. It is expected that recipients will

review this information for applicability to their facilities and consider

actions, as appropriate, to avoid violations of the new Part 20. However, suggestions contained in this information notice are not new NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

The major revision of 10 CFR Part 20 was published on May 21, 1991

(56 FR 23360). This revision adopted the dose-assessment methodology recom- mended by-the International Commission on Radiation Protection (ICRP). The new

methodology'significantly changes the occupational exposure limits for airborne

uranium and thorium compounds. The current regulation requires licensees to

implement the'new-Part 20'by'January'1, 1993. However, licensees should note

,-that.the Commission is proposing to extend the implementation date to

..

Januaryl, 1994. -

Discussion:

Because NRC has adopted the dose-assessment methodology of ICRP 26 and 30,

the new Part 20 contains two changes that can impact greatly on licensees that

experience airborne concentrations of uranium and thorium compounds. These are

changes in occupational exposure limits, and equivalence of internal and

external dose.

9204300066 9 ¢ 5 02 L

cC-r

IN 92- May 6, 1992 As shown in the table below, the new Part 20

occupational airborne concentrations of certain includes a reduction in

compounds. However, the allowed concentrations thorium and uranium

relaxed. Although most changes have been made of other nuclides have been

concern, 10 CFR 20.1201 (e) limits intakes to reflect radiological

of soluble uranium to 10 milligrams in

a week, in consideration of chemical toxicity, at enrichments of 5 percent or less. which is likely to be controlling

Table 1: Old versus New Occupational Exposure Limits

I Compound I Old Part 20 New Part 20

I Appendix B, Table I, Col. 1 I Appendix B, Table

I, Col. 31 I Th-234, class W I 6E-8 pCi/ml I 8E-8 pCi/ml

l Th-234, class Y l 3E-8 pCi/ml _ 6E-8 pCi/ml l

I Th-232, class W I 3E-11 PCi/ml I 5E-13 PCi/ml I

X Th-232, class Y 3E-11 pCi/ml

X I 1E-12 uCi/ml I

I Th-231 _ 1E-6 puCi/ml 3E-6 pCi/ml _

I Th-230, class W 1 2E-12 pCi/ml l 3E-12 pCi/ml L

L Th-230, class Y I lE-11 piCi/ml I 6E-12 pCi/ml l

I Th-228, class W 1 9E-12 pCi/ml I 4E-12 pCi/ml -

I Th-228, class Y I 6E-12 pCi/ml I 7E-12 pCi/ml I

I Th-227 _ 2E-10 uCi/ml 1lE-10 pCi/ml I

U-238i'class D I 7E-11 uCi/ml I 6E-10 PCi/ml l

I U-238, class Y I lE-10 wCi/ml l 2E-11 wCi/ml l

I U-235, class 0 I 5E-10 pCi/ml I 6E-10 pCi/ml

I U-235, class Y I 1E-10 PCi/ml I 2E-11 pCi/ml I

I U-234, class D l 6E-10 pCi/ml I 5E-10 pCi/ml I

I U-234, class Y I lE-10 pCi/ml I 2E-11 puCi/ml I

The relative equivalence of internal and external

to airborne concentrations of radioactive dose means that exposures

part of a worker's total occupational dose particles must now be maintained as

the old Part 20, internal and external doses limit (10 CFR 20.1202). Under

combined. Section 20.1204 states, further, had separate limits and were not

determined through air sampling in the work that internal exposure can be

place or routine bioassay.

If air sampling is chosen as the most accurate

compliance with the new limits may be demonstrated means of tracking dose, isotopic, and particle-size classifications, through precise solubility,

20.1001-20.2401. pursuant to Appendix B to 10 CFR

.. I 1. ,

I

Attachment 2 IN 92-34 May 6, 1992 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance

IsuneIsudt Issued to

92-33 Increased Instrument

Response Time When 04/30/92 All holders of OLs or CPs

Pressure Dampening for nuclear power reactors.

Devices are Installed

92-32 Problems Identified with

Emergency Ventilation 04/29/92 All holders of OLs or CPs

Systems for Near-Site for nuclear power reactors.

(Within 10 Miles) Emer- gency Operations Facili- ties and Technical Support

Centers

92-31 Electrical Connection 04/27/92 All holders of OLs or CPs

Problem in Johnson

Yokogawa Corporation for nuclear power reactors.

YS-80 Programmable Indi- cating Controllers

92-30 Falsification of Plant

04/23/92 All holders of OLs or CPs

Records

for nuclear power reactors

and all licensed operators

and senior operators.

92-21, Spent Fuel Pool Re- Supp. 1 activity Calculations 04/22/92 All holders of OLs or CPs

for nuclear power reactors.

92-29 Potential Breaker Mis-

04/17/92 All holders of OLs or CPs

coordination Caused by

Instantaneous Trip for nuclear power reactors.

Circuitry

92-28 Inadequate Fire Suppres- 04/08/92 All holders of OLs or CPs

sion System Testing

for nuclear power reactors.

OL = Operating License

CP = Construction Permit