United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 75-05: Operability of Category I Hydraulic Shock and Sway Suppressors



BL75005 

                               UNITED STATES 
                      NUCLEAR REGULATORY COMMISSION  
                         WASHINGTON, D. C. 20555 

                             April 14, 1975  

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 BULLETIN NO 75-05 - OPERABILITY OF CATEGORY I HYDRAULIC 
SHOCK AND SWAY SUPPRESSORS 

The subject Bulletin should be dispatched for action to all power reactor 
facilities with operating license or construction permit by close of 
business on April 14, 1975. 

The text of the Bulletin and draft letter to licensees are enclosed for this
purpose. 


                                             John G. Davis 
                                             Deputy Director for 
                                                  Field Operations  
                                             Office of Inspection 
                                                  and Enforcement 

Enclosures: 
As stated 

Distribution: 
See page 2 
.

(Draft letter for action to all power reactor facilities with operating 
license or construction permit) 

                                                     IE Bulletin No. 75-05 

Gentlemen:  

Enclosed is IE Bulletin No. 75-05 which requires action by you with regard 
to your power reactor facility(ies) with an operating license or 
construction permit. Also enclosed are copies of RO Bulletins 73-3 and 73-4 
which are referenced in IE Bulletin 75-05. 

Should you have questions regarding this Bulletin or the actions required of
you, please contact this office. 

                                   Sincerely, 


                                   Director 

Enclosures: 
IE Bulletin No. 75-05 
RO Bulletin Nos. 73-3 and 73-4 

               Approved by GAO, B-180225 (R0072), clearance expires 7-31-77.
               Approval was given under a blanket clearance specifically for
               identified generic problems. 
.

IE BULLETIN NO. 75-05                                      April 14, 1975 

OPERABILITY OF CATEGORY I HYDRAULIC SHOCK AND SWAY SUPPRESSORS 

DESCRIPTION OF CIRCUMSTANCES: 

The Metropolitan Edison Company notified the Region I Office of Inspection 
and Enforcement by telephone on March 21, 24 and 25, 1975, of the finding of
eight inoperable hydraulic shock suppressors on the main steam lines inside 
containment at the Three Mile Island facility. 

The licensee reported that these suppressors were removed for overhaul (seal
replacement) and testing during a planned maintenance program. The 
suppressors were determined to be inoperable (suppressor lockup could not be
achieved) during, piston displacement tests performed by the licensee. The 
tests were performed on a test rig which actuates the piston with air 
pressure. These suppressors, representing equipment originally installed at 
the facility, were specified to achieve lockup at a velocity not exceeding 
10 in. per minute. The test rig at the facility was reported to have a 
capability of testing at velocities up to 50 in. per minute. The specific 
cause of the reported failures has not been determined. Spare suppressors 
were installed as replacements after their acceptability was determined by 
the licensee by test. 

For your information, RO Bulletins 73-3 and 73-4, dated July 27, 1973 and 
August 17, 1973 respectively (copies enclose) discuss some prior experience 
concerning the operability of hydraulic suppressors. 

In general, the installation of hydraulic suppressors provides a system for 
the restraint of Category I systems and components against excessive 
movement during seismic and fluid system transient conditions. Although in 
such a restraint system the failure or inoperability of a single suppressor 
would not normally defeat the design function of the restraint system, it is
desirable to provide for the periodic testing of a representative sample 
from the total population of suppressors to assess the operational 
capability of the restraint system on a continuing basis. 

ACTION TO BE TAKEN BY LICENSEES: 

1.   For all power reactor facilities with an operating license: 

     Review the design and installation of your hydraulic restraint systems,
     and provide the following information to this office in writing within 
     30 days of the date of this Bulletin: 

     a.   The design requirements which the various suppressors are intended
          to meet, such as velocity, acceleration, load, etc. Also, indicate
          the margin available between the 
.

                                  -2- 

          design requirements and the requirements specified for purchase of
          these components. 

     b.   Describe the testing of the hydraulic suppressors conducted by you
          or your supplier (s) prior to installation to assure their 
          operation in accordance with design requirements. 

     c.   Describe the surveillance (including testing) programs now 
          underway or planned by you to assure continued operability of the 
          hydraulic suppressors under the design. Conditions throughout the 
          life of the facility. 
          
2.   For all power reactor facilities with a construction permit: 

     Report to this office in writing within 60 days of the date of this 
     Bulletin or prior to completion of preoperational testing, whichever is
     earlier, the information requested in Items 1.a. thru 1.c. above. 

A copy of your response to items 1 and 2 above should also be sent to: 
Assistant Director for Construction and Operations, Office of Inspection and
Enforcement, USNRC. Washington, D. C. 20555. 
Page Last Reviewed/Updated Tuesday, July 23, 2013