United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Relaxation of Definition of Source Check in Reference to Effluent Radiation Monitors

HPPOS-229 PDR-9111210328

Title: Relaxation of Definition of Source Check in

Reference to Effluent Radiation Monitors

See the memorandum from L. J. Cunningham to J. H. Joyner

(and others) dated December 6, 1990. This memo states that

any proposal by a licensee to relax the definition of a

source check is not acceptable without compensatory

measures to maintain overall effluent control for the

proposed relaxation.

A licensee had submitted an amendment request to move the

existing procedural details of the current Radiological

Effluent Technical Specifications (RETS) to the Offsite

Dose Calculation Manual (ODCM). The licensee, as well as

twenty-two other facilities, used plastic

scintillator / photomultiplier type effluent radiation

monitors that contained either a built-in LED light source

or a secondary check source that did not expose the primary

detector. These alternative source check measurements were

used to meet the monthly qualitative source check

requirement. The definition of "source check" under the

Technical Specifications requires that the channel sensor,

including the primary radiation detector, be exposed to a

radioactive source.

The licensee's amendment request would not change the

definition for source check; however, if the amendment were

approved, the licensee would be free to relax the

definition for source check under its ODCM, provided they

met the criteria that "the over-all level of radiological

effluent control is not reduced." A violation of this

criteria would be a violation of the licensee's Technical


The NRR staff have adopted the position that any proposal

by a licensee to relax the definition of source check,

whether through an amendment request or under its ODCM

pursuant to Generic Letter 89-01, is not acceptable without

the licensee providing compensatory measures for the

proposed relaxation. This is necessary because such

changes on measurements can reduce the overall effluent

control. Therefore, the following conditions must be met:

1. If the detector of concern is used as the primary

means of quantifying radionuclides in effluent streams, the

licensee must proved justification on why an alternative

and technically more accurate measurement (e.g. taking grab

samples) is not available. If an alternative measurement

is not available, then detector specific and other

effluent-related information should be provided either in

the ODCM or other means for the staff to evaluate whether

the overall effluent control will be reduced.

2. If the scintillator plastic / photomultiplier type

detector is used only for detecting radiation that

activates the alarm / trip setpoint, relaxation of the

current source check definition should be accompanied by a

commitment from the licensee to provide compensatory

measures to ensure the overall effluent control not be

reduced over time and usage. A commitment by the licensee

to Cross-check and Document the detector scaler count-rate

with the grab sample result (C&D measurement), where

practical, in lieu of the monthly source check measurement,

would be acceptable. In those situations where the C&D

measurement or other comparable measurements are not

practical, the use of the LED light source and/or secondary

check source measurements would be acceptable.

Regulatory references: 10 CFR 50, Regulatory Guide 1.21,

Regulatory Guide 4.15, Technical Specifications

Subject codes: 6.6, 7.3, 12.12

Applicability: Source

Page Last Reviewed/Updated Thursday, March 29, 2012