United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 74-002A: Metropolitan Edison Company



                                 UNITED STATES
                           ATOMIC ENERGY COMMISSION
                     DIRECTORATE OF REGULATORY OPERATIONS
                                   REGION I
                                631 PARK AVENUE
                      KING OF PRUSSIA, PENNSYLVANIA 19405

                                            February 22, 1974

Metropolitan Edison Company                       Docket Nos. 50-289
Attention:  Mr. J. G. Miller                                  50-320
            Vice President
P. O. Box 542
Reading, Pennsylvania 19603


Gentlemen:

The enclosed Directorate of Regulatory Operations' Information Request 
No. 74-2 is sent to you for response.  Please submit your reply within thirty
(30) days of the date of this letter to this office with a copy to the
Assistant Director for Construction and Operation, Directorate of Regulatory
Operations, U. S. Atomic Energy Commission, Washington, D. C. 20545.

                                       Very truly yours,



                                       James P. O'Reilly
                                       Director

Enclosure:
RO Information Request No. 74-2








7911110107

.

                                   ENCLOSURE


                                       Directorate of Regulatory Operations
                                       Information Request No. 74-2


PWR MAIN STEAM LINE ISOLATION VALVES

In the past several months Regulatory Operations has received notification of
a number of abnormal occurrences involving main steam isolation valves at
various PWR facilities.  Licensees' investigations following preoperational
tests and spurious valve closures have indicated that these valves,
particularly those of the check valve type, may be subject to generic
failures.

To permit evaluation of the extent of the problem, the suitability of specific
valves for isolation purposes under postulated steam line rupture accident
conditions, and the appropriateness of possible remedial measures, you are
requested to provide the following specific information:

1.  Facility name and unit number.

2.  A line diagram or sketch showing the locations of the isolation valve(s)
    with some identification of the type of each valve (check, globe, gate,
    etc.).

3.  Assembly or sectional drawings of each valve type with dimensions and
    identification of material.

4.  Name of the manufacturer of each valve type.

5.  Steam line pressure at full power and at hot stand-by conditions, compared
    with valve design pressure.

6.  Functional design requirements contained in the original design
    specifications for each valve.

7.  An assessment of the adequacy of each valve type to perform the isolation
    function under postulated steam line rupture accident conditions.

8.  Discussion of any operational malfunctions of each valve.

In your response to this request, please also include information relating to
modifications or other methods of resolution which are planned or which may
have been made to valves of this type installed, or scheduled to be installed,
in your facility(ies).

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