Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
GL80033
ENCLOSURE 2
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
April 24, 1980
TO ALL PENDING OPERATING LICENSE APPLICANTS OF NUCLEAR STEAM SUPPLY SYSTEMS
DESIGNED BY BABCOCK AND WILCOX
SUBJECT: ACTIONS REQUIRED FROM OPERATING LICENSE APPLICANTS OF NUCLEAR
STEAM SUPPLY SYSTEMS DESIGNED BY BABCOCK AND WILCOX RESULTING
FROM THE NRC BULLETINS AND ORDERS TASK FORCE REVIEW REGARDING THE
THREE MILE ISLAND UNIT 2 ACCIDENT
In our letter of September 27, 1979, to all pending operating license
applicants concerning followup actions resulting from our reviews regarding
the Three MIle Island Unit 2 accident, we indicated that each applicant
would receive additional guidance from the NRR Bulletins and Orders Task
Force. This guidance would be related to (1) Auxiliary Feedwater (AFW)
systems, and (2) analyses for small break loss-of-coolant accidents and
inadequate core cooling, including guidelines for emergency operating
procedures.
The purpose of this letter is to advise you of the information we require
related to Auxiliary Feedwater systems. The requirements were identified
during the course of the NRR Bulletins and Orders Task Force review of
pressurized water reactor nuclear steam supply systems in light of the Three
Mile Island Unit 2 accident.
Auxiliary Feedwater (AFW) Systems
The Three Mile Island Unit 2 accident and subsequent investigations and
studies highlighted the importance of the AFW system in the mitigation of
transients and accidents. Following the Three Mile Island 2 accident,
operating plants having nuclear steam supply systems designed by Babcock and
Wilcox were shutdown. During these shutdowns short-term actions were taken
to improve the reliability of the AFW system. As part of the long-term
requirements of the shutdown of these plants, more systematic reliability
analysis of the AFW system has been conducted by the licensees. The staff is
currently evaluating these analyses. Also as part of is assessment of the
Three Mile Island Unit 2 accident and related implications for operating
plants, the staff evaluated the reliability of AFW systems for all operating
plants having nuclear steam supply systems designed by Westinghouse and
Combustion Engineering.
The objectives of the staff's study, related to operation of pressurized
water nuclear steam supply system was (a) to identify necessary chances in
AFW system design or related operating procedures at operating plants in
order to assure continued safe operation of these plants, and (b) to
identify other system characteristics in the AFW system design of these
plants which on a long-term basis may require system modifications to
improve reliability.
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To accommodate these objectives the staff reviewed plant-specific AFW system
designs in light of current requirements, and assessed the relative
reliability of which was the initiating event at Three Mile ISland Unit 2,
and other AFW system failure due to common causes, single point
vulnerabilities and human error.
It should be noted that, because of time personnel limitations, our
evaluation of AFW systems was limited to operating reactors at the time
these studies were initiated. Our review of these systems. Some of these
changes were generic and others were plant specific. A summary of the
techniques used in our evaluation is provided in Enclosure 1.*
With respect to operating license applications such as yours, we will
require the you (a) provide an evaluation which show how your AFW system
meets each requirement in Standard Review Plan 10.4.9 and Brach Technical
Position ASB-10-1, (b) perform a reliability evaluation similar in method to
that described in Enclosure 1 that was performed for operating plants and
submit it for staff review, (c) factor the recommendations of Enclosure 1
into your plant design, and (d) respond to Enclosure 2, which requests the
information necessary to determine the design basis for your AFW system flow
requirements and to verify that your AFW system will meet these
requirements.
You are required to provide the information discussed above as an amendment
to your application. Your schedule for submittal should take into
consideration our requirement that both staff approval of your AFW design
and actual accomplishment of any necessary modifications be completed prior
to issuance of a full power license, as reflected in item II.E.1.1 of the
TMI Action Plan (NUREG-0660).
Sincerely,
D. F. Ross, Jr., Acting Director
Division of Project Management
Office of Nuclear Reactor Regulation
Enclosures:
As stated
cc: Service Lists
*Enclosure 1 is Appendix III to the staff generic evaluation of Westinghouse
designed plants, NUREG-0611. The techniques described and recommendations
are applicable to Combustion Engineering and Babcock and Wilcox designed
plants.
