United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 86-38: Deficient Operator Actions Following Dual Function Valve Failures

                                                           SSINS No:  6835 
                                                           IN 86-38         

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, DC 20555

                                May 20, 1986

Information Notice No. NO 86-38:   DEFICIENT OPERATOR ACTIONS FOLLOWING DUAL
                                   FUNCTION VALVE FAILURES 

Addressees: 

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

Purpose: 

This notice is provided to alert licensees to recent events that resulted 
from confusion regarding the proper actions to be taken on failure of dual 
function valves (eg, those that must accommodate emergency core cooling 
system flow and also provide containment isolation) It is expected that 
recipients will review this information for applicability to their 
facilities and consider actions, if appropriate, to preclude similar 
problems at their facilities However, the suggestions contained in this 
notice do not constitute NRC requirements; therefore, no specific action or 
written response is required 

Description of Circumstances: 

The emergency core cooling systems for all light water reactors (LWRs) are 
equipped with numerous valves that serve both core cooling functions and 
containment isolation functions The failure of one of these valves to 
function as designed results in the degradation of at least one of its 
safety functions The following events illustrate instances in which one of 
the functions was not promptly recognized following various types of 
failures 

Peach Bottom Unit 3:  On January 7, 1985, a residual heat removal (RHR) 
system torus spray valve malfunctioned following a reactor core isolation 
cooling (RCIC) system test The valve had been opened to provide suppression
pool cooling for the test and could not be reclosed using the attached motor
operator To satisfy its containment isolation function, the valve was 
closed with a wrench, deactivated, and declared inoperable However, the 
licensee failed to declare the torus cooling function of the RHR train 
inoperable On January 15, with the unit operating at 87 percent power and 
one emergency diesel generator inoperable, causing the equipment including 
the remaining RHR train to be inoperable, the NRC Resident Inspector 
discovered that the previously described train of RHR was inoperable as a 
result of the closed torus spray valve The licensee declared an "Unusual 
Event" and began an orderly shutdown of the unit 



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The operability of the containment cooling mode of RHR requires the 
operability of such equipment as the RHR pumps, the RHR heat exchangers, an 
open flow path to the containment and the high pressure service water (HPSW)
system However, review of the Peach Bottom Unit 3 Technical Specifications 
by the resident inspectors revealed that only the HPSW system is specified 
for containment cooling system operability It is believed that the absence 
of the usual open flow path requirement statement in the plant technical 
specifications contributed to the failure to declare the RHR train 
inoperable The licensee agreed to provide interim administrative controls 
for ensuring operability of the containment cooling subsystem until the 
issue is permanently addressed through a revision to the plant technical 
specifications or by some other means 

Brunswick Units 1 and 2: On May 23, 1984, operations personnel at Unit 2 
observed that the minimum flow valve for the 2A core spray system (CSS) pump
would not stay in the closed position following receipt of a "close" signal 
from the remote manual operator in the control room (These valves do not 
receive a close signal on actuation of the containment isolation system) 
Engineering personnel determined that the control logic for the minimum flow
valves was such that the valves would reopen after closure whenever a low 
flow condition was sensed in the core spray line, including conditions in 
which the CSS pumps were not running 

On June 1, the normally open minimum flow valves for the CSS trains in both 
units were declared inoperable, closed, and deactivated in accordance with 
the technical specification requirement for inoperable primary containment 
isolation valves (PCIVs) The action statement requires that the line be 
isolated if the valve has not been restored to operability within 8 hours 

The technical specifications did not explicitly list an open minimum flow 
path as a requirement for CSS operability, and the licensee failed to 
declare the CSS trains inoperable The licensee did establish procedures 
intended to ensure effective operator action to minimize the potential for 
pump damage in the event of a CSS pump start However, from subsequent 
discussions with the pump vendor, the licensee learned that damage to the 
CSS pumps could occur in as little as l minute of operation at shutoff head 
without the required minimum flow The plant staff re-evaluated the 
situation and concluded that the risk of pump damage with the valves closed 
was unacceptable On June 12, the minimum flow valves were reopened and 
actuator power was restored Administrative controls and special procedures 
were implemented to ensure closure of the valves when required for 
containment isolation The licensee plans to modify the logic to allow 
remote isolation capability for the valves when their associated pumps are 
not running so that minimum flow and containment isolation functions can 
both be ensured 

Dresden Unit 3:  On February 8, 1983, a low pressure coolant injection 
(LPCI) system suppression pool suction valve was cycled closed and failed to 
reopen The valve, which provides both an emergency core cooling system 
(ECCS) and a containment isolation function, was then manually opened and 
electrically deactivated This ensured the LPCI function of the valve, but 
negated the 



                                                             IN 86-38    
                                                             May 20, 1986 
                                                             Page 3 of 4 

containment isolation function Because the swing diesel generator that 
supports the redundant train of LPCI was out of service, an "Unusual Event" 
was declared, and unit shutdown was initiated 

In reviewing the event, it was noted that, during the period when the valve 
was deactivated in the open position, the licensee did not declare the valve
inoperable or enter the technical specification action statement for an 
inoperable PCIV Although the LPCI suction valves are listed in the Dresden 
Final Safety Analysis Report (FSAR) as containment isolation valves, they 
were not listed as such in the technical specifications The licensee was 
requested to submit an application for a license amendment to add to the 
technical specification PCIV list all dual function valves not already 
listed 

Discussion: 

The locations and purposes of dual function valves are diverse They are 
found in the suction lines, discharge lines, and minimum flow lines of a 
variety of diverse ECCS pumps Some of the suction sources are inside 
containment, and some are outside Some recirculation paths penetrate 
containment, and some do not 

In general, limiting conditions for operation (LCOs) for inoperable PCIVs 
allow reactor power operations to continue provided that at least one valve 
in the line having the inoperable valve is closed However, in the case of 
an inoperable dual function valve, this generally would defeat the ECCS 
function of the line and would require entry into the action statement for 
an inoperable ECCS train Alternatively, the decision to maintain the ECCS 
function generally requires entry into the action statement for an 
inoperable PCIV 

The operating staff occasionally may have difficulty determining the most 
appropriate valve position (open or closed) and valve technical 
specification requirement status (enabled or disabled) when a dual function 
valve fails This difficulty is compounded when the technical specifications 
are not specifically provided in the plant license for one or the other 
function of the failed valve, as illustrated by the events described 

With regard to the technical specifications for operability of safety 
systems, all licensees were requested by a generic letter dated April 10, 
1980, to adopt the standard definition that had been developed for NRC's 
Model Technical Specifications That definition requires all necessary 
attendant instrumentation, controls, normal and emergency electrical power 
sources, cooling or seal water, lubrication, or other auxiliary equipment 
that are required for the system to perform its function(s) to be capable of
performing their support functions 




                                                             IN 86-38      
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No specific action or written response is required by this information 
notice 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 Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contacts: S M Long, NRR 
                    (301) 492-8413 

                    E J Leeds, AEOD 
                    (301) 492-4445 

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