United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-39: Inadvertent Isolation of Containment Spray Systems

                                                            SSINS No.:  6835
                                                            IN 84-39 

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

                                May 25, 1984

Information Notice No. 84-39:  INADVERTENT ISOLATION OF CONTAINMENT SPRAY 
                              SYSTEMS 

Addressees: 

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

Purpose: 

This information notice is provided to alert licensees and applicants of the
potential for significant degradation of safety associated with the 
inadvertent isolation of containment spray. Recipients are expected to 
review the information for applicability to their facilities and consider 
actions, if appropriate, to preclude similar problems occurring at their 
facilities. However, suggestions contained in this information notice do not 
constitute NRC requirements and, therefore, no specific action or written 
response is required. 

Description of Circumstances: 

Farley Unit 2 Farley Unit 2 was taken to cold shutdown on October 24, 1982, 
to begin a refueling and maintenance outage. On October 28, 1982, while 
aligning valves for certain scheduled inservice inspections, the licensee 
found the containment spray header isolation valve on each of the two supply
headers locked in the closed position. These valves, located inside the Unit
2 containment building, supply separate, redundant, containment spray rings.
After investigation and record searches of valve movement documentation, the
licensee concluded that the valves had been closed since before the plant 
achieved initial criticality on May 8, 1981. Thus the redundant, containment
spray systems were inoperable during this period and consequently would have
been unable to fulfill their safety function. 

The event was caused by the valves not being in conformance with design 
draw-ings and by the inadequacy of the procedure used by an operator to 
determine the position of the valves. A unique condition developed in these 
valves when the vendor, Westinghouse, made a design change that lengthened 
the valve stem to increase the valve's adaptability to a motor-operated 
valve (however, the motors to operate the valves were never installed and 
the valves remained manually operated). The design change resulted in a 
valve stem that makes the valve appear to be open when it is actually 
closed. That is, the extra long valve stem shows 6 inches of threaded stem 
extending out of the bonnet when the valve is in the closed position. 



8405230319 
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                                                            IN 84-39 
                                                            May 25, 1984 
                                                            Page 2 of 5 

Therefore, operators, who were instructed and trained to observe valve stem 
position to verify the valve positions, erroneously interpreted these valves
as being open when they were, in fact, closed. 

Indian Point Unit 2 

On November 29, 1983, while the licensee was performing a bimonthly (every 
two months) containment spray pump surveillance test during normal 
operation, two motor-operated spray header isolation valves were found in 
the locked closed, de-energized position instead of the required locked 
open, de-energized position. This condition would have prevented automatic 
actuation of the containment spray system during the safety injection phase 
of an accident. 

A review of conditions leading up to this event revealed that on October 12,
1983, during a cold shutdown, these valves were closed and tagged out of 
service so that work could be performed on the reactor coolant system. On 
October 18, 1983, while still in the cold shutdown condition, the tagout was 
cleared even though these valves were specified to remain closed to block 
the containment spray paths while personnel continued to work in the 
containment. Before plant startup, operators were assigned to complete a 
Safety Injection System Check-Off List (COL-12), which should have returned 
the valves to their proper positions before heating the reactor coolant 
system above 350 degrees. 

COL-12 was performed on October 23 and 24, 1983. It required one operator to
ensure the correct valve position and a second operator to verify the posi-
tion. COL-12 directs the operators to the motor control centers to perform 
two verifications for each valve: (1) verify that the position of the valve 
is open and (2) verify that the breaker is de-energized. In the de-energized
condition, position indication for the valve is lost at the motor control 
centers. Verifying position at the motor control center, therefore, requires
energizing the breaker. The first operator assumed that the valve was posi-
tioned by another operator. The second operator assumed the valve was open 
because the breaker was locked in the de-energized position. 

San Onofre Unit 3 

On March 17, 1984, during routine surveillance at approximately 100% power, 
manual isolation valves in both of the containment spray headers were found 
closed, rendering both trains of the containment spray system (CSS) inoper-
able. Misalignment of the isolation valves was caused by improper use of the
valve alignment checklist for the CSS when leaving the shutdown cooling 
mode. 

Unit 3 entered Mode 4 (hot shutdown) following an extended surveillance and 
maintenance outage on February 27, 1984. The valve alignment checklist was 
completed and verified by two operators for the CSS on February 28, which 
confirmed the spray header isolation valves to be open as required for CSS 
operability in Modes 1-3. 

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                                                            IN 84-39 
                                                            May 25, 1984 
                                                            Page 3 of 5 

Because of the inoperability of a safety injection system (SIS) valve, Unit 
3 re-entered Mode 5 (cold shutdown) on February 23. Valve alignments were 
completed for operation of the shutdown cooling system, including closure of
the containment spray header isolation valves. Valve repairs were completed 
for the SIS valve and Unit 3 again entered Mode 4 and left shutdown cooling 
on March 2, 1984. 

Instead of reperforming the entire CSS valve alignment checklist completed 
on February 28, the cognizant control room supervisor, a senior reactor 
operator (SRO), designated valves on the completed February 28 checklist to 
be repositioned and double-verified. At San Onofre an SRO was permitted to 
designate a portion of a checklist to be performed when changes in system 
status do not require the entire checklist to be performed. 
Double-verifications were conducted in this instance for which of the valves 
designated, as required. This repositioning was completed before entry into 
Mode 3 on March 4, 1984. However, because of an oversight by the SRO, the 
containment spray header isolation valves were not designated to-be 
repositioned, and they remained closed until March 17, 1984. 

Other Events 

The staff has observed other events where procedural or personnel errors 
would have prevented operation of the containment spray systems. While most 
of these events only resulted in system inoperability for a few minutes or 
hours, the potential was there for extended plant operation with these 
safety systems inoperable. In addition to the containment spray system, the 
following events include examples of inadvertent valving out of the chemical 
addition tank. The following is a partial list of both types of events: 

Davis-Besse 

On January 12, 1978, both containment spray pumps were found with the 
circuit breakers de-energized. Personnel error resulted in 24 hours of plant 
operation (Mode 4) with the system inoperable. 

D.C. Cook Unit 2 

On May 2, 1978, during change from Mode 5 to Mode 4, containment spray pumps
remained inoperable when control switches were left in the locked out posi-
tion. Procedural and personnel error left the system inoperable for 4 hours.

Davis Besse 

On December 28, 1978, 2 hours after entering Mode 4, containment spray pump 
motor breakers were found in the locked out position. This was caused by an 
operator failing to follow procedures. 

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                                                            IN 84-39 
                                                            May 25, 1984 
                                                            Page 4 of 5 

Indian Point Unit 2 

On September 24, 1980, both containment spray,pump control switches were 
found in the pull-to-lock position by the resident inspector while the plant
was at full power. Plant procedures called for disabling the containment 
spray during containment entry. The licensee was informed of noncompliance, 
with Technical Specifications which require the operability of containment 
spray when the plant is at power, and the procedures were subsequently 
revised. 

Point Beach Unit 1 

On June 21, 1981, while performing periodic surveillance, the spray additive
tank isolation valve was found in the closed position, thus preventing in-
jection of NaOH to the containment spray system. Operator error left the 
valve misaligned for 4 days. 

Farley Unit 2 

On December 26, 1981, while performing surveillance testing, the isolation 
valve on the NaOH spray additive tank was found in the closed position. This
was caused by operator error during position alignment checks. 

Farley Unit 1 

On May 10, 1982, while performing Penetration Room Exhaust and Air 
Filtration System Train Operability and Valve Inservice Test, an operator 
inadvertently closed the containment spray suction valves from the refueling 
water storage tank (RWST). The valves were closed for 7 hours while the 
reactor was at power. 

Surry Unit 1 

On October 16, 1982, isolation valves leading from the chemical addition 
tank were found in the closed position. The cause was attributed to 
personnel failure to perform valve alignment checks. 

Ginna 

On June 13, 1983, while changing modes (cold shutdown to hot shutdown), the 
containment spray pumps were found in the pull-to-lock position. 

Turkey Point Unit 4 

On October 4, 1983, a nonlicensed operator assigned to close the spray 
header isolation valves on Unit 3 (cold shutdown) inadvertently closed the 
identical valves on Unit 4. Unit 4 operated at power with these valves 
closed for approximately 50 hours. 

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                                                            IN 84-39 
                                                            May 25, 1984 
                                                            Page 5 of 5 

Discussion: 

The intent of this information notice is to heighten awareness of industry 
to the potential for significant problems involving the inadvertent 
isolation of containment spray systems (CSSs). During shutdown conditions 
when containment entries are being made, PWR operators find it desirable to 
close the manual isolation valves in each spray header and/or put the spray 
pump control switches in the pull-to-lock position. These actions prevent 
inadvertent containment spray actuation during maintenance and testing 
activities. However, when valve l alignment check-off lists are completed 
before restart, procedural inadequacies or personnel errors have resulted in 
plants going back to power with the isolation valves closed or the pumps in 
the pull-to-lock position, thus preventing automatic operation if needed. 

The NRC recommends that recipients of this notice review their existing pro-
cedures for locking out and returning containment spray systems to operation
and determine whether any changes to the existing procedures would be desir-
able in light of the information contained herein. 

No written response to this information notice is required. If you need 
additional information about 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:  Douglas Pickett, NRR 
                     (301) 492-7876 

                     Eric Weiss, IE 
                     (301) 492-4973 

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