Required Actions Based on Generic Implications of Salem ATWS Events (Generic Letter 83-28)

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                                July 8, 1983



          ATWS EVENTS (Generic Letter 83-28) 

The Commission has recently reviewed intermediate-term actions to be taken 
by licensees and applicants as a result of the Salem anticipated transient 
without scram (ATWS) events.  These actions have been developed by the staff
based on information contained in NUREG-1000, "Generic Implications of ATWS 
Events at the Salem Nuclear Power Plant."  These actions address issues 
related to reactor trip system reliability and general management 

The actions covered by this letter fall into the following four areas: 

1.  Post-Trip Review - This action addresses the program, procedures and 
    data collection capability to assure that the causes for unscheduled 
    reactor shutdowns, as well as the response of safety-related equipment, 
    are fully understood prior to plant restart. 

2.  Equipment Classification and Vendor Interface - This action addresses 
    the programs for assuring that all components necessary for 
    accomplishing required safety-related functions are properly identified 
    in documents, procedures, and information handling systems that are used 
    to control safety-related plant activities.  In addition, this action 
    addresses the establishment and maintenance of a program to ensure that 
    vendor information for safety-related components is complete. 

3.  Post-Maintenance Testing - This action addresses post-maintenance        
    operability testing of safety-related components. 

4.  Reactor Trip System Reliability Improvements - This action is aimed at 
    assuring that vendor-recommended reactor trip breaker modifications and 
    associated reactor protection system changes are completed in PWRs, that
    a comprehensive program of preventive maintenance and surveillance 
    testing is implemented for the reactor trip breakers in PWRs, that the 
    shunt trip attachment activates automatically in all PWRs that use 
    circuit breakers in their reactor trip system, and to ensure that 
    on-line functional testing of the reactor trip system is performed on 
    all LWRs. 


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The enclosure to this letter breaks down these actions into several 
components.  You will find that all actions, except four (Action 1.2, 4.1, 
4.3, and 4.5), require software (procedures, training, etc.) changes and/or 
modifications and do not affect equipment changes or require reactor 
shutdown to complete.  Action 1.2 may result in some changes to the sequence 
of events recorder or existing plant computers, but will not result in a 
plant shutdown to implement.  Actions 4.1, 4.3 and 4.5.2, if applicable, 
would require the plant to be shutdown in order to implement. 

The reactor trip system is fundamental to reactor safety for all nuclear 
power plant designs.  All transient and accident analyses are predicated on 
its successful operation to assure acceptable consequences.  Therefore, the 
actions listed below, which relate directly to the reactor trip system, are 
of the highest priority and should be integrated into existing plant 
schedules first. 

     1.1  Post-Trip Review (Program Description and Procedures) 

     2.1  Equipment Classification and Vendor Interface (Reactor Trip 
          System Components) 

     3.1  Post-Maintenance Testing (Reactor Trip System Components) 

     4.1  Reactor Trip System Reliability (Vendor-Related Modifications) 

     4.2.1 and 4.2.2  Reactor Trip System Reliability (Preventive 
          Maintenance and Surveillance Program for Reactor Trip Breakers) 

     4.3  Reactor Trip System Reliability (Automatic Actuation of Shunt-trip
          Attachment for Westinghouse and B&W plants) 

Most of the remaining intermediate-term actions concern all other safety-
related systems.  These systems, while not sharing the same relative 
importance to safety as the reactor trip system, are essential in mitigating
the consequences of transients and accidents.  Therefore, these actions 
should be integrated into existing plant schedules over the longer-term on a 
medium priority basis.  Some of the actions discussed in the enclosure will 
best be served by Owners' Group participation, and this is encouraged to the 
extent practical. 

Accordingly, pursuant to 10 CFR 50.54(f), operating reactor licensees and 
applicants for an operating license (this letter is for information only for
those utilities that have not applied for an operating license) are 
requested to furnish, under oath and affirmation, no later than 120 days 
from the date of this letter, the status of current conformance with the 
positions contained herein, and plans and schedules for any needed 
improvements for conformance with the positions.  The schedule for the 
implementation of these improvements is to be negotiated with the Project 

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Licensees and applicants may request an extension of time for submittals of 
the required information.  Such a request must set forth a proposed schedule
and justification for the delay.  Such a request shall be directed to the 
Director, Division of Licensing, NRR.  Any such request must be submitted no
later than 60 days from the date of this letter.  If a licensee or applicant
does not intend to implement any of the enclosed items, the response should 
so indicate and a safety basis should be provided for each item not intended 
to be implemented.  Value-impact analysis can be used to support such 
responses or to argue in favor of alternative positions that licensees might 

For Operating Reactors, the schedules for implementation of these actions 
shall be developed consistent with the staff's goal of integrating new 
requirements, considering the unique status of each plant and the relative 
safety importance of the improvements, combined with all other existing 
plant programs.  Therefore, schedules for implementation of these actions 
will be negotiated between the NRC Project Manager and licensees. 

For plants undergoing operating license review at this time, plant-specific 
schedules for the implementation of these requirements shall be developed in 
a manner similar to that being used for operating reactors, taking into 
consideration the degree o completion of the power plant.  For construction 
permit holders not under OL review and for construction permit applicants, 
the requirements of this letter shall be implemented prior to the issuance 
of an operating license. 

This request for information was approved by the Office of Management and 
Budget under clearance number 3150-0011 which expires April 30, 1985. 
Comments on burden and duplication may be directed to the Office of 
Management and Budget, Reports Management Room 3208, New Executive Office 
Building, Washington, D.C. 20503. 

                               Darrell G. Eisenhut, Director 
                               Division of Licensing 

Required Actions Based on Generic Implications of Salem ATWS Events

Page Last Reviewed/Updated Thursday, March 25, 2021