IE Circular 76-03 - Radiation Exposures in Reactor Cavities
CR76003
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
September 10, 1976
J. P. O'Reilly, Director, Region I
N. C. Moseley, Director, Region II
J. G. Keppler, Director, Region III
E. M. Howard, Director, Region IV
R. H. Engelken, Director, Region V
IE CIRCULAR 76-03 - RADIATION EXPOSURES IN REACTOR CAVITIES
The subject document is transmitted for issuance by close of business
September 13, 1976. The Circular should be issued to all holders of Reactor
OL's for action and to applicants for, or holders of Reactor CP's for
information. Also enclosed are draft copies of transmittal letters.
Dudley Thompson, Acting Director
Division of Field Operations
Office of Inspection and
Enforcement
Enclosure:
Circular 76-03
Transmitted via Wylbur
9/10/76 11:40 a.m.
.
(Transmittal letter for Circular 76-03 to each holder of a NRC Operating
License.)
Addressee:
The enclosed Circular 76-03 is forwarded to you for action. The same
document is being transmitted to each applicant for, or holder of a
Construction Permit for information. Therefore, if you have a nuclear power
plant in the construction stage, you will also receive a copy of Circular
76-03 which will not require a separate response.
Signature
(Regional Director)
Enclosure:
IE Circular 76-03
.
(Transmittal letter for Circular 76-03 to each applicant for, or holder of a
Construction Permit.)
Addressee:
The enclosed Circular, 76-03, is forwarded to you for information. No
response is required. If you are also the holder of a NRC Operating License,
you will also receive a copy of Circular 76-03 which will require a
response.
Signature
(Regional Director)
Enclosure:
IE Circular 76-03
.
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
IE Circular No. 76 - 03
DATE: September 13, 1976
RADIATION EXPOSURES IN REACTOR CAVITIES
DESCRIPTION OF CIRCUMSTANCES:
On March 18, 1976, an employee at the Zion station received a "whole body"
radiation dose of 8 rems or more upon entering the cavity beneath the
reactor vessel during a refueling outage. On April 5, 1976, a similar
reactor cavity entry at Indian Point resulted in a 10-rem whole body dose to
a licensee employee. A similar entry on October 5, 1972 caused a 5-rem dose
to a Point Beach employee.
These three overexposures appear to have been caused by failure to
appropriately control entry into high radiation areas, failure to conduct
adequate surveys and failure to compensate for exposure rate variations that
can occur in various areas in power reactors, e.g., the cavity beneath the
reactor vessel. With the incore thimbles and detectors inserted into the
core, radiation levels in the cavity appear to be low. With the thimbles or
detectors withdrawn into the cavity, however, exposure rates of hundreds or
possibly thousands of roentgens per hour can exist. Overexposures can occur
in seconds.
All three overexposure events involved entry into potentially high radiation
areas without surveys and/or special controls over equipment which could
cause transients in the exposure rate.
.
IE Circular No. 76 - 03
Date: September 13, 1976
ACTION TO BE TAKEN BY LICENSEES:
While the three exposures above occurred at pressurized water reactors,
similar situations could develop at other types of reactors, e.g., pneumatic
irradiation equipment areas (research reactors) and traveling incore probe
equipment areas (boiling water reactors). Accordingly, holders of power,
test and research reactor operating licenses are to complete the following:
1. Perform a thorough review of plant areas and operations to identify
high radiation areas, both continuous and transient, as defined in
10 CFR 20.202(b).
2. Verify that entryways into high radiation areas are conspicuously
posted and locked or otherwise controlled in such a manner as to
explicitly identify the nature of the hazard, appropriately control
entry, and require adequate pre-entry surveys,
3. Ensure that radiation protection procedures and radiation protection
training and retraining programs specifically address the matter of
control of and access to such areas and initiate appropriate retraining
of all plant personnel,
4. Ensure that the procedures governing personnel entry into all actual or
potential high radiation areas permit such entry only after appropriate
management review and approval so that conditions within the area are
known and not subject to change while the area is occupied,
5. Periodically audit whatever controls result from item 1-4, above, to
ensure their continued effectiveness, and
6. Confirm by written reply within 60 days that the actions for items 1-4
above, have been or are being taken. A record, detailing findings,
actions taken, and actions to be taken, should be retained for review
by NRC during the next radiological safety inspection.
This request for information was approved by GAO under a blanket clearance
number B-180225 (R0072); this clearance expires July 31, 1977.
Page Last Reviewed/Updated Thursday, March 25, 2021