United States Nuclear Regulatory Commission - Protecting People and the Environment

Seismic Qualification of Auxiliary Feedwater Systems (Generic Letter 80-88)

(GL 80-88)
                                UNITED STATES 
                        NUCLEAR REGULATORY COMMISSION 
                           WASHINGTON, D.C. 20555 

                              October 21, 1980 

ALL OPERATING PRESSURIZED WATER REACTOR LICENSEES 

SUBJECT: SEISMIC QUALIFICATION OF AUXILIARY FEEDWATER SYSTEMS 

After the accident at Three Mile Island (TMI), a large amount of our attention
focused on the capability of plants to reliably remove shutdown decay heat. 
The NRC Action Plan (NUREG-0660, Section II.E) identifies post-TMI actions 
that are underway concerning this general subject. While we recognize that 
alternate ways may be available for removing decay heat following anticipated 
transients or accidents, removal of heat through the steam generators would be
the first choice for accomplishing a safe plan, shutdown. For this reason, the
design of auxiliary feedwater (AFW) systems should satisfy the same standards 
applied to other safety related systems in the plant. Accordingly, the current
acceptance criteria for AFW systems which are applied to construction permit 
and operating license reviews are contained in Section 10.4.9 of the NRC's 
Standard Review Plan (SRP), which treats the AFW system as an engineered 
safety feature. However, only the recently licensed facilities have been 
reviewed against this section of the SRP. A copy of that SRP Section is 
attached as Enclosure 1. The purpose of this letter is to identify our generic
concerns related to the seismic design capabilities of AFW systems in 
operating PWRs and to describe a program which we intend to undertake in 
reviewing the capability of operating PWRs to remove decay heat following an 
earthquake. 

Since the accident at TMI, we have been reviewing AFW systems for all 
operating PWRs to assess the need to backfit design and procedural 
modifications. Our review has been based on a deterministic evaluation, 
primarily against the SRP, in conjunction with a reliability study utilizing 
event and fault tree analyses to determine dominant failure modes. During the 
course of these reviews, we have informally questioned licensees regarding 
seismic capabilities of AFW system piping and components but our interest has 
been specific to the potential for seismically induced damage to the system 
water source and subsequent damage to the pumps due to loss of suction. Our 
concern now has turned to the capability of the entire system. Attached as 
Enclosure 2 is a table listing some of the information informally received 
from licensees which describes the capability of systems to perform, in the 
event of an earthquake. 

We have recently conducted a preliminary probabilistic assessment of 
seismically induced loss of decay heat removal for plants which are considered
not to have seismically qualified AFW systems. The results of the study are 
contained in an NRC memorandum dated August 8, 1980 a copy of which is 
attached as Enclosure 3. We intend to complete a more detailed evaluation 
within the next several months to determine whether there is sufficient safety
justification for long term operation until any required plant modifications 
have been completed. .                                                       October 21, 1980        
                  

                                   2


The evaluation program developed by the staff will include a site visit to a 
few plants to better define the scope and depth of our continuing review. 
Following the site visits, within the next few weeks, we will request of each 
PWR licensee information on the capability of each plant to satisfactorily 
remove decay heat following an earthquake. The primary purpose of our 
evaluation program is to develop consistent and balanced criteria for making 
backfit decisions should they prove necessary. This technical issue, including
our evaluation program, was recently discussed with our Advisory Committee on 
Reactor Safeguards. Their letter which resulted from the meeting is attached 
as Enclosure 4. 

Although the NRC evaluation effort is continuing, we strongly encourage you to
promptly re-examine your plants capability to remove decay heat following an 
earthquake. If your review should identify any modifications necessary to 
ensure this capability, you should begin to plan for such activities. 

Sincerely, 

Darrell G. Eisenhut, Director 
Division of Licensing 

Enclosures: 
1. SRP Section 10.4.9
2. Table of Seismic Capabilities 
3. 8/8/80 Memo: Mattson to Eisenhut 
4. ACRS Letter 

.                                                                                                                                                                                                                                                                                                                                        Enclosure 2

                     SEISMIC QUALIFICATION OF AFW SYSTEMS

                  X indicates that the licensee has not
                  analyzed the component(s) for the SSE


                                                                                                                                                                                                                                                                                                                                              | Water | Initiation
                                                                                                                                                                                                                                                                                                                                              | Supply|     and
                                                             Pumps/ | Piping |  Valves/  |  Power   | P | S |   Control
                                                             Motors |        | Actuators | Supplies | r | e |   System  
                               |        |           |          | i | c |           
 I  Arkansas 2                 |        |           |          | X |   |           
 |  Calvert Cliffs 1/2         |        |           |          |   |   |      X    
 C  Ft. Calhoun                |        |           |          | X | X |           
 E  Maine Yankee               |        |           |          |   | X |      X    
 |  Millstone 2                |        |           |          |   | X |      X    
 K  St. Lucie                  |        |           |          |   | X |      X    
 I  Beaver Valley              |        |           |          |   |   |           
 W  D. C. Cook 1/2             |        |           |          | X |   |           
 E  Farley                     |        |           |          |   |   |           
 S  H. B. Robinson             |        |           |          |   |   |           
 T  Indian Pt. 2/3             |        |           |          |   | X |           
 I  Kewaunee                   |        |           |          | X |   |           
 N  North Anna 1               |        |           |          |   |   |           
 G  Point Beach 1/2            |        |           |          | X |   |           
 H  Prairie Island 1/2         |        |           |          | X |   |           
 O  Salem 1                    |        |           |          |   | X |           
 U  Surry 1/2                  |        |           |          |   |   |           
 S  Trojan                     |        |           |          | X |   |           
 E  Turkey Pt. 3/4             |        |           |          |   | X |           
 K  Zion 1/2                   |        |           |          | X |   |           
 I  Arkansas 1                 |        |           |          | X |   |      X    
 B  Crystal River 3        X   |    X   |     X     |     X    | X | X |      X    
 &  Davis-Besse                |        |           |          | X |   |           
 W  Oconee 1/2/3               |        |           |          | X | X |           
 K  Rancho Seco                |        |           |          |   | X |           
 I  Palisades                  |        |           |          |   | X |      X    
 S  Ginna                      |        |           |          | X |   |           
 E  Haddam Neck                |        |           |          |   |   |      X    
 P  San Onofre 1           X   |    X   |     X     |     X    |   |   |      X    
 K  Yankee Rowe            X   |    X   |     X     |     X    | X | X |      X    
 

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