ML20234D600
| ML20234D600 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 06/24/1987 |
| From: | Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20234D590 | List: |
| References | |
| 50-454-87-22, NUDOCS 8707070272 | |
| Download: ML20234D600 (7) | |
See also: IR 05000454/1987022
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U. S. NUCLEAR REGULATORY COMMISSION
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REGION III
Docket No. 50-454
License No. NPF-37
Licensee: Commonwealth Edison Company
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Post Office Box 767
Chicago, IL 60690
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Facility Name:
Byron Station, Unit 1
Inspection At: Byron Station, Byron, IL
Inspection Conducted: May 26 - June 12, 1987
Inspector:
P. G. Brochman
J. M. Hinds, Jr.
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Approved B
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MV//7
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Reactor Projects Section IA
Date
Inspection Summary
Inspection on May 26 - June 12, 1987 (Report No. 50-454/87022(DRP))
Areas Inspected:
Special, unannounced safety inspection by the resident
inspectors to review the circumstances surrounding the inoperability of both
trains of the spray additive (sodium hydroxide) portion of the Unit 1
containment spray system.
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Results: One apparent violation of NRC r3quirements was identified: (entry
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into Mode 4 with an inoperable spray additive system and failure to place
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the unit in Mode 5 with an inoperable spray additive system).
This apparent
violation is of safety significance and had the potential to affect the
public's health and safety.
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8707070272 870629
DR
ADDCK 0500
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DETAILS
1.
Persons Contacted
Commonwealth Edison Company
R. Querio, Station Manager
- R. Pleniewicz, Production Superintendent
R. Ward, Services Superintendent
W. Burkamper, Quality Assurance Superintendent
- L. Sues, Assistant Superintendent, Operating
G. Schwartz, Assistant Superintendent, Maintenance
- T. Joyce, Assistant Superintendent, Technical Services
J. Schrock, Operating Engineer, Unit 1
- M. Snow, Regulatory Assurance Supervisor
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F. Hornbeak, Technical Staff Supervisor
- E. Zittle, Regulatory Assurance Staff
- G. Stauffer, Assistant Technical Staff Supervisor
- R. Williams, Technical Staff
- W. Pirnat, Regulatory Assurance
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- H. Erickson, Maintenance Staff Assistant
- J. Langan, Regulatory Assurance
The inspector also contacted and interviewed other licensee and
contractor personnel during the course of this inspection.
- Denotes those present during the exit interview on June 12, 1987.
2.
purpose
This inspection was conducted to review the circumstances surrounding the
loss of control of two locked valves, IC5018A and ICS018B, in the spray
additive [ sodium hydroxide (Na0H)] portion of the Unit I containment
spray (CS) system.
Valves ICS018A and ICS018B were found shut, instead
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of locked open, during a NRC verification of the CS system operability.
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With these valves shut both trains of the spray additive system were
physically inoperable from May 2 - 26, 1986.
3.
Description of the Event
On May 1,1987, a request was made to revise Byron Operating Procedure B0P
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CS-S, " Containment Spray System Recirculation to the RWST," to provide
additional assurance that the Na0H tank would be isolated from CS system
during recirculation so that the NaOH would not contaminate the RWST
(Refueling Water Storage Tank). This was the result of experience at
the licensee's Zion Station. To accomplish this, temporary change number
87-0-688 was issued to modify B0P CS-5 and steps were added to the
procedure to shut additional valves in the line from the Na0H tank to
the CS eductors (ICS018A and ICS0188) and to drain the Na0H remaining
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in the piping. Steps to restore valves ICS018A and ICS018B to the locked
open position were included in the temporary change.
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On May 2,1987, operating department personnel performed Byron Operating
Surveillance IBOS 6.3.2.b-1, " Phase B Containment Isolation, Containment
Ventilation Isolation, and Containment Spray Actuation by Manual
Initiation." Step F.1.2 requires that the CS system be aligned for
operation per B0P CS-5.
Valves ICS018A and 1C50188 were unlocked and
shut. The surveillance was successfully performed; however, the BOS
provided its own directions for system restoration and did not direct a
return to B0P CS-5; consequently, valves ICS018A and 1C5018B remained
shut until they were discovered to be incorrectly positioned on May 26,
1987 and were subsequently locked open.
4.
Chronology of Events
4/22/87
The valve lineup for the CS system, 80P CS-M1, is completed and
valves 1CS018A and ICS018B are verified to be locked open.
5/01/87
Temporary change 87-0-688 is issued to B0P CS-5 to shut valves
ICS018A and 105018B to prevent Na0H contamination of the RWST
when the CS system is recirculated to the RWST.
Instructions
to realign valves ICS018A and 105018B to their proper position
for system restoration are also provided.
5/02/87
Surveillance 180S 6.3.2.b-1 is performed and step F.1.2 directs
that the CS system be aligned for recirculation per BOP CS-5.
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Valves ICS018A and 1C5018B are unlocked and repositioned shut.
The surveillance is completed and section 6 of the BOS provides
its own restoration instructions and the need to reposition
valves ICS018A and 1C5018B is not recognized. With these
valves shut the Na0H tank was isolated from the CS system
eductors.
5/06/87
At 0900 the unit entered Mode 4 with both trains of the spray
additive system inoperable, contrary to Technical Specification 3.0.4.
5/12/87
By 1500 the spray additive system had been inoperable for 120
hours and action was not taken to place the unit in Cold
Shutdown [ Mode 5] within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, contrary to
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Technical Specification 3.6.2.2.
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5/15/87
At 1412 the unit entered Mode 5 for unrelated reasons
(maintenance) approximately 221 hours0.00256 days <br />0.0614 hours <br />3.654101e-4 weeks <br />8.40905e-5 months <br /> after entering Mode 4.
5/23/87
At 1343 the unit again entered Mode 4 with both trains of the
spray additive system inoperable, contrary to Technical Specification 3.0.4.
5/26/87
At approximately 1655 valves ICS018A and ICS018B were
discovered to be unlocked and shut during a NRC walkdown of
the CS system.
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5.
Evaluatic,n of the Event
The Byron FSAR, Section 6.5.2 states that the CS system is designed to
remove fission products, nrimarily elemental iodine, from the containment
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atmosphere for the purpose of minimizing the offsite radiological
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consequences following a design-basis loss-of-coolant-accident [LOCA].
Section 6.5.2.1 states, in part, that the CS system is designed tn remove
sufficient iodine from the containment atmosphere to limit, in the event
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of a LOCA, the offsite and site boundary doses to values less than the
limits of 10 CFR 100. The spray additive system adds Na0H via the CS
system eductors to change the pH level of the water in containment.
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Section 6.5.2.1 discusses the failure of one of the trains of the spray
additive system and states, in part, that even with a single failure
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sufficient Na0H is added to the water in containment sump to form a 8.55
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pH solution, when combined with the spilled reactor coolant system water
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and the water from the safety injection systems. This pH is necessary to
attain an iodine portion coefficient greater than 4E+3 which will result
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in a decontamination factor of 100 in the containment atmosphere.
With valves ICS018A and 1050188 shut, both of the trains of piping from
the Na0H tank ta the CS system eductors were isolated and the spray
additive system was physically inoperable.
However, the rest of the CS
system was operable and could have sprayed water into containment had the
system been actuated.
Technical Specification 3.0.4 requires that entry into en operational
mode shall not be made unless the conditions for the Limiting Condition
for Operation are met. Technical Specification 3.6.2.2 requires that the
spray additive system shall be operable in modes 3 and 4 with a spray
additive eductor capable of adding sodium hydroxide (NaOH) to a
containment spray system pump flow. With the spray additive system
inoperable, restore the system to operable status within the next 120
hours or else be in Cold Shutdown [ Mode 5] in the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
For the
spray additive system to be operable, valves ICS018A and 1C5018B must be
open, so that NaOH can flow from the storage tank to each of the spray
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additive eductors, when the containment spray system is actuated.
On May 6, 1987, and May 23, 1987, Unit 1 entered Mode 4 with valves
ICS018A and 1C5018B shut rendering the spray additive system inoperable.
The failure to have an operable spray additive system upon entry into
mode 4 is an apparent violation of Technical Specification 3.0.4
(454/87022-01a(DRP).
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From 0900 on May 6, 1987, to 1412 on May 15, 1987, [221 hours] Unit I
was in Modes 3 and 4, and valves ICS018A and 105018B were shut for
greater than 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> rendering the spray additive system inoperable.
The failure to place the unit in Mode 5 within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> is an
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apparent violation of Technical Specification 3.6.2.2
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(454/87022-01b(DRP).
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6.
Corrective Actions Initiated by +.he Licensee
a.
The licensee verified that the remaining valves in the Unit 1 CS
system were in their correct position, exceot 1C5045, which was
locked open instead of locked shut. The required position for valve
1CS045 had been changed by a modification and the valve lineup
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procedure revised, but the valve had not been repositioned. The
licensee verified that the valves in the Unit 2 CS system were in
their correct position.
b.
The licensee revised Byron Administrative Procedure BAP 1310-4,
" Temporary Changes to Permanent Procedures," to require that when a
temporarily changed procedura is used in conjunction with other
procedures, the temporary changed procedure must reference the other
procedure and the safety review must examine any interactions
between the two procedures.
If the other procedure is not.
referenced on temporary change form, a new safety review will have
to be performed on the combined use of these procedures, before the
procedures can be used together.
c.
The licensee has revised the locked equipment program to require
that all changes from the normal position for a locked component
be documented on the kcked equipment deviation log, BAP 330-3T1.
Previously surveillance procedures were exempt from this
requirement. A time limit on how long an abnormally positioned
locked equipment can remain in that condition will be indicated on
thelockedequipmentdeviationlog(e.g...aspecificdate, Mode
change, or some other milestone).
d.
The licensee has installed a temporary status board to track all
unlocked components. The information contained on the status board
consists of the:
component name, date unlocked, date required to be
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returned to service, and reason why component is unlocked.. This
temporary status board will be used until the changes described in
paragraphs e and f below are in place.
e.
The licensee is changing the present system of locks used in the
locked equipment program from.five different cores (trd n 1A, IB,
2A, 2B, and common equipment) to individually keyed locks for the
approximately 600 components in the program.
Presently a "B1" key
could open any locked valve in Unit 1 on an "A" train component, be
it a 1A auxiliary feedwater, diesel generator, or containment spray
valve.
Master keys will be available to the operators for use in
emergencies. Until these changes are completed all "B" series keys
are being stored in a locked container and the shift supervisor must
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authorize the issuance of the key.
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f.
The licensee intends to create a new status board to hold each of
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the approximately 600 new keys. A status board will be created
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with a place for each of these 600 keys. The status board will be
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designed so that it will be easy to inventory the keys present and
it will be readily apparent when a key has been removed. A review
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of the new locked equipment status board will be added to the mode
change checklists.
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7.
Conclusion
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This event has indicated significant weaknesses in the licensee's program
for the control of locked equipment.
The application of the locked
equipment deviation log and of other requirements specified in the locked
equipment program (BAP 330-3) to procedures other than surveillance was
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not consistent. Additionally, paragraph C.I.e of BAP 330-3 requires that
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when a piece of equipment is unlocked, the lock and chain are to be
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securely fastened. When the valves were found, the locks were not
secured as required by the BAP.
The inspector reviewed several operating procedures for other
safety-related systems (Auxiliary Feedwater, Diesel Generator, Spent Fuel
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Pool Cooling, and Safety Injection) which unlocked valves and determined
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that no mention of BAP 330-3 nor the locked equipment deviation log BAP
330-3T1 was made. A review of several Residual Heat Removal (RH) system
. operating procedures showed that the locked equipment program and locked
equipment deviation log were referenced; however, the number of the
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referenced procedures had been deleted over one year ago and in fact had
been deleted before the current revision of the RH procedures were
issued.
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Problems were indicated in the review of changes to procedures when the
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changed procedure may be used, in part, by other procedures. Barring
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some type of computerized crossreference system the inspectors are unsure
if this problem would have been caught in a normal procedure review. As
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a result the licensee needs to evaluate the use of stand alone procedures
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or using the same procedure to align equipment for testing and then
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realign the equipment for operation using the same procedure.
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The safety significance of the inoperable spray additive system is
mitigated by several facts. The unit was in Mode 3 after a shutdown of
approximately 80 days, reducing the energy present in the core to drive a
release. The iodine inventory present in the core was reduced by its
decay following the shutdown.
Had a containment spray actuation occurred
during this time period, the operators in the control room would have had
indication of Na0H flow and NaOH tank level. Additionally, a low Na0H
flow alarm is installed in the control room.
Consequently, operators
could have been dispatched to repair the malfunctioning spray additive
system on a containment spray actuation.
As a result of this problem redundant trains of a safety-related system
were simultaneously inoperable. The NRC has serious concerns with the
licensee's performance in the area of safety-related system operability.
In the last two years there have been four previous events (three events
within the last six months) in which redundant trains of safety-related
system were simultaneously inoperable (both trains of Residual Heat
Removal inoperable during various times between March and July 1985; both
trains of Safety Injection inoperable in December 1986; both trains of
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the Essential Service water makeup pumps in February 1987; and two of
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three required trains of the non-accessible area exhaust filter plenum in
February 1987). The NRC recognizes that the root causes for these events
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were different; however, the overall affect on safety-related system
operability is considered unacceptable. The NRC is concerned that taken
together these events are indicative of inadequate performance by
licensee management in ensuring operability of safety-related systems.
8.
ExitInterview(30703)
The inspectors met with licensee representatives denoted in Paragraph 1
at the conclusion of the inspection on June 12, 1987. The inspectors
summarized the purpose and scope of the inspection and the findings.
The inspectors also discussed the likely informational content of the
inspection report with regard to documents or processes reviewed by the
inspectors during the inspection. The licensee did not identify any such
documents or processes as proprietary.
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