United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-23: Main Steam Isolation Valve (MSIV) Leakage

                                                            SSINS No.: 6835 
                                                            IN 82-23 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                   OFFICE OF INSPECTION AND ENFORCEMENT  
                           WASHINGTON, D.C. 20555 

                               July 16, 1982 

IE INFORMATION NO. 82-23:  MAIN STEAM ISOLATION VALVE (MSIV) LEAKAGE  

Addressees: 

All boiling water power reactor facilities holding an operating license or a 
construction permit. 

Purpose: 

This information notice is provided as notification of events that may have 
safety significance. It is expected that recipients will review the 
information for applicability to their facilities; however, no specific 
action or response is required at this time. 

Description of Circumstances: 

IE has completed a survey of MSIV performance at BWRs for the years 1979 
through 1981. IE found that 19 of 25 operating BWRs had MSIVs which failed 
to meet, during one or more surveillance tests, the limiting condition for 
operation (LCO) which specifies the maximum permissible leak rate. The 
number of MSIV test failures exceeded 151 and occurred with MSIVs supplied 
by all three MSIV vendors, i.e., Atwood & Morrill, Crane, and Rockwell. 

Measured leak rates which exceeded the LCO ranged from greater than 11.5 
standard cubic feet per hour (scfh) to 3427 scfh. Twelve stations had 57 
MSIV tests with results greater than 11.5 scfh and less than 100 scfh, and 
five stations (nine units) had 66 MSIV tests with results between 100 and 
3500 scfh. Four other licensees had more than 24 test failures but did not 
measure, estimate, or report the magnitudes of the leak rates. These results
are summarized in Attachment (1) and are shown in detail in Attachment (2). 

This information indicates that some MSIVs may not adequately limit release 
of radioactivity to the environment if called upon to do so. NRC is 
considering the need for improved MSIV maintenance, more frequent MSIV 
testing or installation of leakage control systems. 

8204210393 
.

                                                           IN 82-23  
                                                           July 16, 1982  
                                                           Page 2 of 2 

If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this office. 

                              

                                   Edward L. Jordan, Director 
                                   Division of Engineering and 
                                     Quality Assurance 
                                   Office of Inspection and Enforcement 

Technical Contact:  R. W. Woodruff 
                    49-24507 

Attachments: 
1. Distribution of MSIV Test Failures 
2. Adverse MSIV Test ResUlts for 1979 - 1981 
3. List of Recently Issued IE Information Notices  

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