United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-19: Loss of High Head Safety Injection Emergency Boration and Reactor Coolant Makeup Capability

                                                           SSINS No.:  6835 
                                                           IN 82-19 

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C.  20555

                                June 18, 1982

Information Notice No. 82-19:  LOSS OF HIGH HEAD SAFETY INJECTION 
                                  EMERGENCY BORATION AND REACTOR COOLANT 
                                  MAKEUP CAPABILITY 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or 
construction permit (CP). 

Purpose: 

This information notice is provided as a notification of an incident that 
may have safety significance.  It is expected that recipients will review 
the information for applicability to their facilities.  No specific action 
or response is required at this time. 

Description of Circumstances: 

On February 12, 1982, Duke Power Company's McGuire Unit 1 experienced a loss
of high head safety injection emergency boration and reactor coolant makeup 
capability.  Hydrogen from the positive displacement pump (PDP) suction 
dampener entered the common suction of the charging system, causing both 
centrifugal charging pumps (CCPs) and the PDP to be inoperable.  The system 
was restored within 30 minutes.  The unit was in Mode 1, at 50% of full 
power at the time of the event. 

While CCP 1A was operating, the licensee was preparing to return the PDP to 
service following maintenance.  Upon opening of the suction isolation valve 
to the PDP, air and hydrogen in the PDP suction piping entered the common 
suction of the charging system.  Control room personnel observed oscillation 
of the CCP 1A motor current and charging flow.  They immediately shifted to 
CCP 1B and tripped CCP 1A.  Approximately 30 seconds later, similar 
indications were received from CCP 1B.  It was tripped, and letdown was 
isolated.  When the nuclear equipment operator who had opened the isolation 
valve heard a page announcement that charging had been terminated, he 
immediately called the control room.  As a result of his call, the control 
room operators suspected that gas from the PDP suction dampener was entering 
the common suction line. The operator was instructed to reclose the 
isolation valve.  The suction piping and the CCPs were vented, CCP 1B was 
restarted, and charging and letdown were reestablished.  The licensee does 
not intend to return the PDP to service until a change is made to preclude 
recurrence of this event. 
.

                                                            IN 82-19 
                                                            June 18, 1982 
                                                            Page 2 of 2 

The suction dampener installed at McGuire (see Attachment 1) consists of a 
vertical section of 12-inch pipe with hydrogen gas overpressure.  Water 
level in the suction dampener is controlled automatically by two solenoid 
valves. Based on comparison of water levels in the suction dampener and its 
reference leg, one valve supplies gas when the suction dampener level is too 
high, and one valve vents gas when the level is too low. 

Prior to the event, the reference leg had been inadvertently drained, erron-
eously indicating that the water level in the suction dampener was too high. 
Therefore, hydrogen was continuously supplied to the suction damper causing 
the gas to enter the suction piping common to the CCPs and the PDP.  Failure
to properly vent the PDP and its associated piping prior to opening the 
valve that isolates the equipment from the common suction of the CCP may 
have contributed to the event. 

During review of this event by the NRC staff, it became apparent that a 
single failure in the non-safety-related portion of the system resulted in 
loss of centrifugal and positive displacement safety injection charging 
pumps.  There is a concern that the potential of a single component 
malfunction, personnel error, or maintenance error in the safety or 
non-safety related portion of the system could lead to the same consequences 
even though the system may be of a different design than that used at the 
McGuire Station. 

If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this office. 


                                  Edward L. Jordan, Director 
                                  Division of Engineering and 
                                    Quality Assurance 
                                  Office of Inspection and Enforcement 

Technical Contact:  W. Marinelli
                    301-492-8073

Attachments:
1.  Charging Pump Flow Diagram
2.  List of Recently Issued IE Information Notices

Page Last Reviewed/Updated Tuesday, November 12, 2013