United States Nuclear Regulatory Commission - Protecting People and the Environment

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. 

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