IE Circular No. 81-09, Containment Effluent Water That Bypasses Radioactivity Monitor
SSINS No.: 6830
Access No.:
810330373
IEC 81-09
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
July 10, 1981
IE Circular No. 81-09: CONTAINMENT EFFLUENT WATER THAT BYPASSES
RADIOACTIVITY MONITOR
Description of Circumstances:
At Indian Point Units 2 and 3 and at H. B. Robinson Unit 2, licensee reviews
of service water systems have identified unmonitored effluent paths from
containment. Although containment cooler water effluent is monitored,
containment cooler fan motor cooling water bypasses the monitors by joining
the containment cooler water effluent downstream of the radiation monitoring
equipment. This represents a potential unmonitored release path if the
containment is at design pressure due to a design basis accident (DBA) and
if leaks are present in the fan motor cooler system. Similar designs may
exist at other plants. Appropriate monitoring of direct discharges (from
containment to the environment following a DBA) having the potential to
exceed the limits specified in 10 CFR Part 20 is required.
Recommended Actions:
1. All water system effluents that are not automatically isolated by a
high-containment-pressure containment isolation signal and that flow
directly to the environment from containment should be reviewed to
determine whether or not a pathway exists for "significant" unmonitored
discharge. A "significant" discharge, for purposes of this circular, is
a discharge where projected concentrations in unrestricted areas are
likely to exceed the concentrations listed in 10 CFR Part 20, Appendix
B, Table II, column 2, with the containment at design pressure due to
a design basis accident and with maximum credible leakage, such as a
single completely severed cooler tube, assumed to be present in the
water system inside containment. You may take credit for design
pressure in the water system being higher than containment design
pressure only for cases where neither single failures, nor operation in
degraded modes as permitted by Technical Specifications under a
limiting condition of operation (LCO), are likely to result in
operation of the water system at water pressures lower than the
containment design pressure.
2. All water system effluents that are not automatically isolated by a
high-containment-pressure containment isolation signal and that flow
directly to the environment from containment should be reviewed to
determine whether or not any "significant" radioactive discharge can be
isolated once it is detected. The review should include evaluation of
the capability of the system to be isolated without interruption of any
safety-related functions. Isolation of the system's inlet as well as
its discharge may be required
.
IEC 81-09
July 10, 1981
Page 2 of 2
to prevent radioactive discharge through the inlet piping to the inlet
piping of a parallel system and/or to the environment.
3. Corrective actions to install detection and isolation methods that
provide performance consistent with Technical Specification
requirements should be initiated for any "significant" unmonitored
and/or unisolable discharge pathways.
Although no written response to this circular is requested, a report and
corrective actions may be required by applicable Technical Specifications in
the event an unmonitored and/or unisolable effluent pathway is identified.
If you desire additional information regarding this matter, please contact
the appropriate IE Regional Office.
Attachment:
Recently Issued IE Circulars
Page Last Reviewed/Updated Tuesday, March 09, 2021