United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

The Meaning of "... May Have Caused or Threatens to Cause..." in 10 CFR 20 .403

HPPOS-236 PDR-9111210355

Title: The Meaning of "... May Have Caused or Threatens to

Cause ..." in 10 CFR 20.403

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

(and others) dated June 20, 1991. The words "may have

caused" in 10 CFR 20.403 apply to a retrospective view of

the event at the time prompt reporting is being considered,

and the words "threatens to cause" apply to a prospective

view at that time. In consideration of the ordinary

meanings of "threaten", NRC understands "threaten to cause"

in 10 CFR 20.403 to mean "probably is about to cause" or,

in other words, "likely will cause soon." The health

physics position was written in the context 10 CFR 20.403,

but it also applies to "new" 10 CFR 20.2202.

A comment on the proposed revision of "old" 10 CFR 20.403

(55FR 19890, 5/14/90) and the applicability of 10 CFR

20.403 to one circumstance of an enforcement case (Hatch,

Inspection Report No. 50-321/91-05) has resulted in a

clarification of the meaning, with respect to exposure and

releases, of the condition, "... any event involving

licensed material that may have caused or threatens to

cause ..." in 10 CFR 20.403 (a) and (b). [Note: Similar

wording is found in the requirements of 10 CFR 20.2202 (a)

and (b).] The words "may have caused" in 10 CFR 20.403 [or

10 CFR 20.2202] apply to a retrospective view of the event

at the time prompt reporting is being considered. The

words "threatens to cause" apply to a prospective view at

that time.

The words "... may have caused ... [an] exposure ... or ...

release" in 10 CFR 20.403 [and 10 CFR 20.2202] are used in

the context of the rapid assessment of the significance of

an event with respect to determining whether or not the

event must be reported "immediately" or "within 24 hours."

Somewhat similar words, "substantial potential for an

exposure or release ..." are used in supplement IV.C.4 of

the NRC Enforcement Policy (10 CFR Part 2, Appendix C) in

the context of determining the significance of an event

with respect to determining the Severity Level of a

violation after it has been determined that the violation

has occurred. However, the words "may have caused ..." in

10 CFR 20.403 [or 10 CFR 20.2202] do not have exactly the

same meaning as the words "substantial potential ..." in

the Enforcement Policy. The words "may have caused" do not

refer to an exposure or release that (at the time the need

for prompt reporting is being considered) is known not to

have occurred even though there was a "substantial

potential" for the exposure or release.

For an example of the difference between "may have caused"

and "substantial potential," consider a hypothetical event

(based on the event at Hatch) in which there was a

"substantial potential" for someone entering a particular

room and receiving a whole-body exposure of 5 rems or more

while in the room. When considering the need for prompt

reporting of an event, if it is known that someone entered

the room and that the person received, or may have

received, an exposure of 5 rems or more, then that event is

reportable under 10 CFR 20.403 [or 10 CFR 20.2202].

However, if it is known that no one entered the room, the

event is not reportable under 10 CFR 20.403 [or 10 CFR

20.2202] even though a substantial potential may have

existed for someone to enter the room and receive the

exposure.

With respect to the requirements of 10 CFR 20.403 [or 10

CFR 20.2202], the preceding discussion has considered

situations in which an exposure or release that exceeded

the specified values is known not to have occurred. If the

conditions for a reportable release or overexposure are

known to have been present (i.e., because of the known

circumstances, there is at least a possibility that such an

event did occur), and the licensee is unable to establish

definitively that the suspected event actually did not

occur, then the licensee must make a report. The report is

not an admission on the part of the licensee that the event

did occur; it merely allows NRC the opportunity to

participate in evaluating whether or not the event did

occur while the facts and circumstances are still fresh in

the minds of the cognizant individuals.

Although not reported to the NRC, information on

significant radiological exposures and releases at nuclear

power reactors that fall below the reporting thresholds of

10 CFR 20.403 [or 10 CFR 20.2202] (including events that

have a "substantial potential for an exposure or release

...") usually is available to inspectors in the files of

licensee radiological event tracking systems or as feedback

from resident inspectors. These events could result in

violations. In consideration of the ordinary meanings

(dictionary definitions) of "threaten," NRC understands

"threatens to cause" in 10 CFR 20.403 [or 10 CFR 20.2202]

to mean "probably is about to cause" or, in other words,

"likely will cause soon." The clarifications given in this

NRR memorandum have been coordinated with OE, NMSS, AEOD

and RES. OGC has no legal objections.

Regulatory references: 10 CFR 20.403, 10 CFR 20.2202

Subject codes: 2.2, 12.7

Applicability: All

Page Last Reviewed/Updated Thursday, March 29, 2012