Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
October 7, 1988
Information Notice No. 88-79: MISUSE OF FLASHING LIGHTS FOR HIGH
RADIATION AREA CONTROLS
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice alerts addressees to problems involving the misuse of
flashing lights for high radiation area (HRA) controls. Five events involving
improper access control of high radiation areas are discussed. Inappropriate
use of such access controls could lead to potentially significant, inadvertent
radiation exposures. It is expected that recipients will review the informa-
tion for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Background:
In several of the events discussed, it is apparent that plant workers and
supervisors did not fully understand the technical specification (TS)
requirements for HRA access control; therefore, a brief summary of the
evolution of HRA controls for power plants could be useful.
NRC regulations (10 CFR 20.202) define a high radiation area, in part, as
having radiation levels that could cause whole-body doses in excess of
100 millirem in 1 hour. Specific HRA access control requirements (e.g.,
locking and positive control over entry) are contained in 10 CFR 20.203(c)(2).
These basic Part 20 HRA requirements were developed before the development of
commercial power reactors.
NRC recognized that requiring power reactor licensees to lock all areas that
exceeded 100 mrem per hour was not appropriate because of the large number of
such areas, as well as the general state of sophistication of the typical
radiation protection program (which includes RWP controls, surveillance pro-
grams, comprehensive worker training, and professional technical HP staff,
among others). Therefore, beginning in the mid-1970s, TS amendments were
issued to some power reactor licensees allowing them to lock only areas
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IN 88-79
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with dose rates of 1000 mrem/hr or more, providing that additional specified
controls were implemented. Subsequent to these amendments, certain TS were
further amended to recognize that there were particular HRAs that, because of
their configuration, it was not reasonable to enclose and lock. This change
allowed the use of a flashing light in place of a locked enclosure but was
only permitted for unusual cases if no enclosure could reasonably be
constructed around the component or area.
Description of Circumstances:
In recent months, NRC inspections have identified at least five incidents
where licensees have misused the TS requirement that allows the use of
flashing lights in lieu of a locked enclosure around a high radiation area as
acceptable practice for any high radiation area. The examples listed in
Attachment 1 describe situations in which the level of personnel protection
was unnecessarily reduced because of misuse of Standard Technical
Specification (STS) 6.12. Corrective actions taken included (1) locking the
door to an HRA enclosure that already existed, (2) installing an enclosure
around the HRA, or (3) shielding a localized source such that dose rates were
reduced to less than 1000 mrem/hr. Although doses in excess of NRC limits did
not result from any of these events involving misuse of HRA access controls,
all situations had the potential of resulting in a significant radiation dose.
Discussion:
Presently, STS 6.12 addresses an alternative control method for locked
entrances for HRAs in accordance with 10 CFR Part 20. In part, STS 6.12
states that "For individual areas accessible to personnel with radiation
levels such that a major portion of the body could receive in one hour a dose
in excess of 1000 mrem [measurement made at 18" from the source of
radioactivity] that are located within large areas such as PWR containment,
where no enclosure exists for purpose of locking, and no enclosure can be
reasonably (emphasis added) constructed around the individual areas, then
that area shall be barricaded, conspicuously posted, and a flashing light
shall be activated as a warning device...." As described in Attachment 1,
several licensees have misused flashing lights and barricades to control
access to HRAs having radiation levels greater than 1000 mrem/hr in situations
in which more positive access control was possible by constructing a lockable
enclosure or locking the enclosure that already existed.
All power reactor licensees having the above-described provision in their
technical specifications are permitted to use barricades, posting, and
flashing lights to control access to high radiation areas wherein dose rates
of 1000 mrem/hr or more exist and that cannot be reasonably enclosed.
Conversely, if it is reasonable to construct a locked enclosure, then access
control with barricades, posting, and flashing lights is not permitted.
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IN 88-79
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No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the
technical contacts listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: Thomas H. Essig, NRR
(301) 492-3146
James E. Wigginton, NRR
(301) 492-1136
Attachments:
1. Examples of Misuses of STS 6.12
2. List of Recently Issued NRC Information Notices
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Attachment 1
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Page 1 of 2
Examples of Misuses of STS 6.12
x Washington Nuclear Project (WNP)-2 (Inspection Report No. 50-397/88-22)
During an inspection conducted in June 1988, NRC inspectors noted an area
containing sources having radiation levels up to 1500 mrem/hr at
18 inches that was equipped with a lockable door. The door was unlocked;
access control was handled through use of a flashing light and barricade.
A health physics (HP) supervisor employed by the licensee stated that he
believed that STS 6.12 allowed warning lights to be used at any HRA
location in lieu of locking the area or constructing enclosures. Discus-
sions with equipment operators revealed that four out of the five opera-
tors interviewed did not know the purpose of the flashing lights; the
fifth individual knew their purpose but felt training provided him on
this subject was deficient.
x Point Beach (Inspection Report Nos. 50-266/88013 (DRSS) and 50-301/88012
(DRSS))
While performing radiation surveys in April 1988 on the 66-foot level of
the Unit 1 Containment Building during a fuel element transfer, NRC
inspectors noted that a procedurally required HRA flashing red light was
installed but not in use. The HRA existed because of radiation emanating
from the fuel element transfer canal through a 2-inch gap between the
containment wall and the floor. Dose rates up to 6000 mrem/hr existed in
this area during fuel transfer. Just before the inspection, a
night-shift refueling supervisor had the flashing red lights turned off
by the HP organization after he found them to be a distraction.
x Wolf Creek (Inspection Report No. 50-482/88-09)
In March 1988, an NRC inspector noted that a Durateck portable
demineralizer skid was posted as an HRA with radiation levels in excess
of 1000 mrem/hr. A rope barrier and a flashing light were used to
control access to the immediate area around the skid. The maximum
radiation level at 18 inches from the source was 1300 mrem/hr. Although
it was feasible to construct an enclosure around this skid, the licensee
believed that the area containing the demineralizer skid constituted a
"large area" as used in STS 6.12.
x Vogtle (Inspection Report No. 50-424/88-13)
During February 1988, an NRC inspector noted that access to an HRA enclo-
sure containing a spent resin line was through a lockable door and that
the key had broken in the lock. Access to the area was controlled as an
HRA by a flashing light and a barricade. Dose rates up to 3500 mrem/hr
(18 inches from the source) existed inside the HRA. As was the case with
WNP-2, the licensee believed that STS 6.12 permitted the use of flashing
lights in lieu of locking the HRA access door.
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Attachment 1
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x Farley (Inspection Report Nos. 50-348/88-02 & 50-364/88-02)
One room and a portion of another were posted as an HRA having radiation
fields greater than 1 rem/hr. The entrance to this area was not locked,
although it was barricaded by three yellow and magenta ropes, a flashing
red light, and high radiation area/exclusion area warning signs. Radia-
tion exposure rates in the inner room ranged up to 240 R/hr at contact
and approximately 150 R/hr at 18 inches from the surface of a tank. As a
result of miscommunications, two workers entered the area on December 28,
1987, to perform decontamination activities without either the
appropriate monitoring equipment or being accompanied by an
HP technician. One worker entered the area and worked approximately
5 feet from the spent fuel pool demineralizer. After approximately
5 minutes, this worker observed that his low-range dosimeter was
offscale; he immediately exited the room and reported to an HP
technician.
Although no exposures in excess of NRC limits resulted from these activi-
ties (maximum dose was 455 mrem), the situation represented a significant
potential for an overexposure because of the lack of communication and
the lack of adequate access controls. The licensee in this case also
believed that STS 6.12 permitted the use of flashing lights and rope
barriers as an access control to an HRA having radiation levels greater
than 1 rem/hr in lieu of locking the door to the area.
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