ML20236R890
| ML20236R890 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/20/1987 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | Calvo J Office of Nuclear Reactor Regulation |
| References | |
| LIC-87-783, NUDOCS 8711240086 | |
| Download: ML20236R890 (65) | |
Text
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Omaha Public Power District 1623 Harney Omaha. Nebraska 68102 2247 402/536 4000 November 20, 1987 LIC-87-783 Mr. Jose A. Calvo, Project Director Project Directorate IV Division of Reactor Projects III, IV, & V and Special Projects U. S. Nuclear Regulatory Commission Washington, DC 20555
References:
1.
Docket No. 50-285 2.
LER-87-025 dated October 23, 1987 (LIC-87-720) 3.
Meeting with Region IV, held October 29, 1987 4.
Meeting of with NRC in Bethesda, MD., held November 5, 1987 5.
Letter OPPD (R. L. Andrews) to NRC (R. D. Martin) dated November 4, 1987 (LIC-87-744)
Dear Mr. Calvo:
SUBJECT:
Summary of Meeting with NRC held November 13, 1987, Regarding the Instrument Air System at Fort Calhoun Station.
Omaha Public Power District (OPPD) met with NRC personnel on November 13, 1987, to discuss the Instrument Air System at Fort Calhoun Station.
OPPD has dedicated significant amount of resources to resolve any and all concerns related to the inadvertent introduction of water into our Instrument Air System on July 6, 1987.
This letter is provided as a follow-up to the presentations on November 13, 1987.
In addition to that information presented, OPPD has prepared and i
included additional information in order to assist you in your evaluation.
l Information from the breakout discussions on the In-Service Testing Program, l
and on seismic adequacy have been included as noted in the attachments.
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PDR ADOCK 05000285
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> T, l Based on the evaluations-conduct'ed:and corrective actions taken, OPPD.has-P$
. concluded. that the Fort Calhoun : Station isLsafe to ' operate.
This is evidencedt l
M ifrom the; fact that essentially;all moisture-has?been removed from the:
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,cinstrument' air system,Jas~ indicated by. continuing dew point measurements.
W l, P NC ' LAdditional corrective actions' are' planned, defined and scheduled.to. support the'
- continuedisafe operation'of-thejstation._ If you have questions or comments
- ',. < ttregarding these; matters,'do not' hesitate to contact us.
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- R' t L'. " Andrews iDivision! Manager-p l Nuclear Productions y
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. Enclosure s
.'cc;-Dennis-Crutchfield, NRC Director, Div. of Reactor Projects j.III,nIV, V,'.and Special Projects b
- R.i D.: Martin; NRC Regional-Administrator'r.
- L..JG Callan, NRC Director,~ Div. 'of Reactor Projects 4 -
1 iFrank Schroeder, NRC Assistant Director, Region.IV-
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._ Reactors and'Special" Projects 1A.LBournia, NRC Project. Manager P.<H. Harrell, NRC Senior Resident Inspector
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- LeBoeuf,: Lamb, Leiby &LMacRae n
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INDEX
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- SECTION-TOPIC-
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.Executiive Summary-'
11:
-(II ;
- o. DescriptionLof. July 6,11987:and August 25,-1987. Water s
-Intrusi Diesel Damper Failure.on Incidents, andLSeptember'23,' 1987 m..
M in III
- 0 PPD's Assessment of Affected Safety Related Components and Corrective Actions.Taken.to Date z
,m-
' IVf Conclusions. Supporting Safe Operation 4
- V
- Program.to Demonstrate Continued Safe Operation g
VI
.0ther. Specific corrective Actions Planned or in Progress
_VII'
- Summary;of_ Inservice Testing Program Enhancements-y.:
o o EVIII...
~ Seismic 1 Concerns:
m,f'
- IX )
Summary and Slides from November 13, 1987 Meeting I
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SECTION I EXECUTIVE
SUMMARY
1 On July.6, 1987,.during conduct of a fire protection surveillance test, water was inadvertently introduced into the instrument air system at Fort Calhoun.
l e -
The system was blown down and water was determined to have been limited to the lower.two levels of the auxiliary building (i.e., below elevation 1025.)
l Following a series of blowdowns and tests, the water was believed to have been essenti. ally eliminated.
However, on September 23, 1987, one of the emergency 3
diesel generators automatically tripped on high temperature.
This high
[
temperature was-traced to the failure of the diesel exhaust damper to open I
fully. The damper failed to open due to clogging with residue in the pilot valve on the damper operator.
Residue was probably introduced as a result of 2
the July 6, 1987 water intrusion event.
A separate, unrelated event involved mispositioning of a valve on August 25, 1987 which also introduced a lesser quantity of water into the air system.
In this instance, the scope was limited to the immediate vicinity of the water plant and affected valves were immediately blown down eliminating water from the air system.
Based on these events, OPPD performed a detailed and thorough investigation of the July 6,1987 event, and the operational and management decisions made subsequent to that event.
OPPD fully believes that the reasons for the event i
are known.
From a safety ' significance perspective, OPPD determined that the event on July 6,1987, was potentially more significant than originally considered.
In retrospect, the decision to continue operating was contrary to a philosophy of conservatum toward operational safety. OPPD understands this matter and is taking steps towards its resolution.
The importance of accurate, timely and complete communications with the NRC has
.been reemphasized to OPPD personnel.
" Deportability", through 10 CFR 50.72 and 50.73 mechanisms, and meetings with site resident inspectors, will be properly utilized.
From a corrective action and operational perspective, the Fort Calhoun Station is safe to operate today. The assessment of water ingress and corrective actions, both completed and in progress, demonstrate that water has been effectively removed from the instrument air system and presents no further hazards to safe operation of the Fort Calhoun Station.
Further, the consequences of residue left as a result of water entry into the system and/or the effects of high humidity or water vapor carry over have been assessed through system component inspections and operator teardowns.
The residue also presents no hazards to safe operation, nor do the consequences associated with higher humidity or water vapor carryover.
The continued valve cycling program and operator teardowns will detect any long term effects of residue or residual water.
1-1 I
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g LSection~I-(Continued) 4 a
JCorrectiveiactions planned'or taken as a result'of this event are detailed and comprehensive and will preclude degradation and misoperation of both the
?; operation. physical plant systems, and the human resources supporting Fort Calho g+
- 0 PPD is' dedicated to the safe' reliable operation of the Fort Calhoun Station.
To. support this philosophy, a complete appraisal of our nuclear operation is-
.being undertaken. ' The ' appraisal will be completed by June,1988.
0perational safety is being reemphasized.- Safety. evaluations continue to receive increased attention..This is amplified by the recent implementation laf an -improved process 'for conducting safety evaluations. Timeliness of corrective Lactions'is also receiving increased attention.
o L
10 PPD is providing increased resources and emphasis in the area of event
- investigations.
TheLwork in progress before this event in the area of root cause: analysis is one aspect of this effort. OPPD will also use resources from Lthe.onsite or offsite-safety review groups to facilitate necessary
. investigative efforts.
Above all, OPPD is committed to the operation of Fort Calhoun Station in a manner which is in no way. detrimental to public health and safety. The information provided in this: letter demonstrates that fact.
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SECTION 11 DESCRIPTION OF THE JULY 6. AUGUST 25. AND SEPTEMBER 23 EVENTS
SUMMARY
OF JULY 6. 1987 EVENT The' Instrument. Air System was interfaced with the fire protection system as a result of a modif_ication completed in 1985.
This modification interfaced Fire Protection deluge system for the diesel generator rooms was converted from a wet pipe to' a dry pipe system in order' to eliminate potential freezing problems during winter diesel operation.
(See Figure II-1)
Instrument air was supplied to the dry pipe valve, FP-513, through two check valves (IA-575 and IA-576) and an air maintenance device in order to hold the valve clapper in the closed position.
When the system is activated (for either fire protection or testing), the air pressure is rapidly depleted and the clapper opens, supplying fire protection water to the deluge headers.
Following actuation of the dry pipe valve, it must be manually reset by removing an access cover and relatching the clapper in the closed position.
At approximately 1045 on July 6,1987, clarified water entered the Instrument Air System from the Fire Protection system during a surveillance test of the diesel generator room dry pipe sprinkler system.
Evaluation of this event has shown that.it occurred as a result of two factors:
1.
Instrument Air check valves IA-575 and IA-576 were prevented from closing by foreign material.
9 2.
The operator performing the test failed to properly reset the dry pipe valve as a result of'a misleading procedure and inadequate training on the unique' dry pipe valve.
The air maintenance device was bypassed thus removing another check valve and orifice that could have prevented and/or restricted flow into the air system.
During the reset process, as performed, a flow path existed through FP-514, FP-513, IA-576, IA-575 and IA-569. The Fire Protection System pressure is approximately 30 psi greater than Instrument Air pressure.
Thus, water flowed into the Instrument Air System.
The operator noted that the air-side and water-side pressure gauges (PI-6515 and PI-6516) both read fire main pressure. He knew that this was not possible if the clapper valve was properly reset.
He then closed FP-514, isolating the water flow, and informed the shift supervisor.
It is estimated that approximately 10-50 gallons of clarified water were introduced into the Instrument Air System during the few minutes this flow path existed.
Several equipment problems occurred over the next hour as a result of the water intrusion.
1.
The bubbler-based level indicator for the diesel generator fuel oil storage tanks failed high. An alternate means of level indication was initiated.
2.
HCV-485, CCW outlet valve from shutdown cooling heat exchanger AC-4B, failed open. Corrective maintenance was initiated.
11-1 c
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' ty Section II (Continued)
. 3.
Water was observed at FCV-269X, the demineralized water makeup flow o
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controller to'the boric acid system.
Corrective maintenance was initiated.
i Several actions were completed on July 6 to return both the Instrument Air and the Fire Protection Systems to full functional status.
1.
Check valves IA-575 and IA-576 were cleaned, tested, and returned to
-service, i
2.
The dry pipe valve was properly reset.
3.
Operations personnel and Instrument and Control Technicians conducted blowdowns to remove water from the Instrument Air System.
4.
Engineers were assigned to. evaluate and define what further actions were required to address the event in more detail.
The immediate. blowdown program demonstrated that the water was confined to the lower two levels of the auxiliary building, below elevation 1025'.
No water was found in the turbine building or the intake structure. No water was introduced into the containment building, since the instrument air penetration is above elevation 1025'. By the end of the work day on July 6, it was believed that substantially all the water had been removed from the Instrument
.' n.
Air System.
As a result of Item 4. above, a detailed an'd documented set of blowdowns was in'itiated on_ July 9, 1987.
Five hundred and fifteen (515) individual components were included in the scope of the blowdown, and all safety-related
. air accumulators below elevation 1025' were drained, (except for the diesel
- generator radiator exhaust damper accumulators, as discussed later). Water was
'found in less than 10% of the components. As much as possible, valves and i
other components were cycled following blowdown to verify their operability.
4 lThe blowdown program was repeated in August 1987 for those components which had water during the July documented blowdown.
Eight (8) components on four (4) risers along with the Post Accident Sampling System (PASS) showed moisture during this second blowdown, and were scheduleJ to be checked again during September.
As discussed in OPPD LER 87-025; and later in this section, Diesel Generator No. 2 tripped on high coolant temperature during a surveillance test on September 23, 1987.
The most probable cause was the failure of the radiator exhaust dampers to open fully.
The pilot valve orifice was found to be restricted by foreign material, most likely resulting from the interaction of water, o-ring lubricant, and other operator components.
The accumulator was found to contain 50% water.-
OPPD has developed specific actions to ensure the continued integrity of the i
Instrument Air System and programmatic improvements to address the generic weaknesses pointed out by these events. OPPD placed heavy emphasis on removing the water from the Instrument Air System.
In retrospect, the potential safety 11-2 m
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k-4 Section' II.'(Continued).
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. significance of the July 6 event was not sufficiently evaluated at the time of its. occurrence.
Evaluations have subsequently been. performed in order to assess the potential safety significance of the event.
The event should have been reported as required by 10 CFR 50.72 and.50.73.
Based on our review, E
. however, critical safety functions (see Section IX) would have been maintained if a design basis accident had occurred coincidentally with the water intrusion i'
event. One of the corrective actions is addressed in Section VI that will 0
1 ensure that operational events are promptly evaluated for safety significance.
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SUMMARY
OF THE AUGUST 25. 1987 Incident At sometime prior to August 24, 1937,. the instrument air valve to DW-CV-86 in ithe. service building water plant area was opened. This provided a flow path 1
L for-water to enter'the instrument air distribution header in the water plant.
Component; failures were identified on;three separate components in the water plant between August 24 and August 26 of 1987. These components were the demineralized water surge". tank level recorder on AI-104 (M.0. 874104), the level control valve (LCV-1515) for demineralized water surge tank (M.0.
'874120), and the caustic dilution water heater temperature control valve
' recorder (DW-TICA-1)(M.0.'874135). These problems were caused by water in the m$ -
instrument air lines to those components. These components were returned to F g, service on August 27, 1987.
, Subsequent actions were taken to ensure that there was no further water 9
intrusion into the instrument air system.
This ultimately included physically F,. o
. disconnecting and capping the tagged closed isolation valve, thereby leaving L
the instrument air system physically separated from DW-CV-86.
S_UMMARY OF THE SEPTEMBER 23. 1987 EVENT At 0644 hours0.00745 days <br />0.179 hours <br />0.00106 weeks <br />2.45042e-4 months <br /> on September 22, 1987, while Fort Calhoun Station was operating at full power, Diesel Generator No. 1 (DG-1) was started to prove operability prior to_ performing maintenance on the, exhaust pipe for Diesel Generator No. 2
- (DG-2).
On September 23,1987, at 0906 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.44733e-4 months <br /> CDT, DG-2 was manually started, followed by synchronization and loading at 0911 hours0.0105 days <br />0.253 hours <br />0.00151 weeks <br />3.466355e-4 months <br /> per Operating Instruction 01-DG-2 as required by Surveillance Test ST-ESF-06.
At 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br />, DG-2 automatically shutdown due to high coolant temperature Personnel were
.immediately dispatched to determine the cause of the overheating.
Investigations revealed that the' air operated radiator exhaust air damper YCV-871F may not have automatically fully opened when the diesel was running,
.thus restricting the required air flow through the radiator, and subsequently l'
overheating the diesel coolant.
The air to operate the damper is supplied via a pilot valve.
The air to the pilot valve is provided by either the instrument air system or an accumulator.
The damper.is normally closed to limit the diesel's exposure to cold outside air and it'is designed to be open when the diesel is running.
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N I
t SECTION III ASSESSMENT OF WATER INGRESS IMPACT ON SAFETY REl.TED COMPONENTS
.,.c The Instrument Air System is one of two compressed air systems in operation at the Fort Calhoun Station.
Both the instrument air and plant air systems are nominal 100 psi air systems which can be supplied by any one of three two-stage air compressors.
Instrument air is fed by a separate header through a large air' receiver, one air dryer and a 20 micron filter prior to serving any components on the system. The Instrument Air System provides pressurized air
- to approximately 1200 components throughout the plant. Of these 1200 compo-Lnents, a large number are air operated valves.
However, instrument air is also used for tank level. bubblers, pressure transmitters, pneumatic controllers and l
air maintenance functions such as the dry pipe fire system used in the diesel generator room.
l Of the 1200 components relying on instrument air for some type of function, approximately 500 are safety related components. Of the 500 safety related
(
components, there is a smaller set of approximately 160 components that are required to perform an active function for one of the USAR design basis
- accidents, with an even smaller set of approximately 40 components that have accumulators. installed to ensure performance of an active safety function with a complete loss of instrument air.
Excluding the small set of components relying on _ air. accumulators, the Instrument Air System has been classified in accordance with the USAR and maintained as a non-safety grade system since i
plant startup in 1973.
Thus, only a very small part of the Instrument Air System is considered safety grade, that part being those sections of the l
. Instrument Air System downstream of the check valves which isolate accumulators for the components that rely up(n accumulators for some post-accident active function'.
With the ingress of water into the Instrument Air System on July 6, 1987, two significant concerns were created. The first concern related to the impact of water on the operability of compcnents normally operated by instrument air.
The second concern is focused on the potential for a longer term degradation of air operated components caused by the residue from those systems wetted or increased humidity and/or water vapor carried to those components not phys-ically wetted. OPPD's response to each of the two concerns is addressed
. separately below.
Prior to discussing corrective actions implemented by OPPD, an understanding of the materials of construction for the instrument air and its associated components is appropriate.
The piping and tubing for the Instrument Air System i
, downstream of the air receiver is predominantly ASTM B-88, Type K, copper.
The valve operators are constructed of a variety of materials, but the valve
. operator bodies predominantly tend to be either cast iron or carbon steel.
Air regulators associated with the valve operators are predominantly constructed of aluminum or brass materials. The ASCO solenoids used to direct air flow to and from the operators are predominantly brass and stainless steel. Accumul ators associated with the Instrument Air System are normally an alloy of carbon steel.
Generally, any moving parts within the Instrument Air System will be a material of low corrosion susceptibility; i.e., brass, aluminum, stainless steel, or nonmetallic diaphragms or seating surfaces.
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s Section$III-(Continued)~
it LWith'the lngress of. water into the Instrument Air System on July 6, 1987, t0 PPD's initial corrective actions were focused upon eliminating the shorter term concern,.i.e., water in the' system.- Within an hour of becoming aware of a potential: for water entering the Instrument Air System, the Fort Calhoun I
. Station staff: initiated an aggressive effort to blow down all air lines that y
were'potentially wetted.
Early in this effort,. there was a high level of F
confidence that the water had entered the system through the diesel generator L'.
- room' fire protection header.
The blowdown of the system started at those
. components nearest to the point of entry and was sequentially expanded to those o
-areas most likely wetted.
By the'end of that first day,.the blowdown program had effectively: demonstrated that the physical intrusion of water had been limited to those sections of the Instrument Air System located below the 1025'
-level.of the auxiliary building.,It should be noted that the extensive work
.that has been~ conducted since that first day of the event has provided evidence-R that water was not carried past the originally determined boundaries.
Although..the blowdown' effort conducted on~ July 6 ' removed the bulk of water that had entered the system, a more rigorous blowdown and component cycling program to ' ensure complete removal of all water was implemented. This blowdown cycling program of over 500 components was intended to include all components located below the 1025' level of the auxiliary building as well as a sampling of valves
'in other. areas.to.. verify that water had not travelled beyond the 1025' level or into other sections of the plant. This program consisted of first blowing down each component to eliminate water from the~ air lines, then cycling the component with a follow-up blowdown to ensure water removal from the appropriate component actuator.
In addition to the blowdown and cycling i
program, all safety related air accumulators located in the auxiliary building below the 1025 level were also drained.
For each component drained or blown down, data-sheets were maintained to identify quantities of water and whether l
l or not cycling of the component was performed.
Fifty-nine of the 500 plus components exhibited some amount of moisture during blowdown (Figure III-1).
Additionally, water was observed in four air accumulators; one having 12-1/2%
,of'its volume filled with water; the other three less than 1%.
Approximately 1
one month later, a third series of component blowdowns was conducted which encompassed components off of'those risers (11 of 24) within the effected area which had exhibited water in-one or more components. During this third series of blowdowns, very small quantities of water, primarily mist, were observed for nine components fed from 4 of the 11 risers tested. A fourth series of F
blowdowns was scheduled to blowdown these four risers again in September, and was scheduled independent of the September 23 diesel generator damper failure.
'Following the failure of the air damper for the Diesel Generator No. 2
.. radiator, OPPD reinitiated its blowdown and cycling program for all components located in the auxiliary building below the 1025' level. A limited set of
-valves inside containment was also added to this fourth series of blowdowns to i
further validate that water had not passed beyond the 1025' level (all air
. operated. valves inside containment received instrument air through a connection
.that passes.into containment at approximately the 1029' level).
During this fourth series of blowdowns, water was found only in the post accident sampling system.
In addition,. water was found in the air accumulators for the radiator L.
air dampers for both diesel generators as documented in our Licensee Event Report No.87-025.
Because an ambiguity in the instrument air drawings had III-2
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- Section III (Continued) contributed to a failure to' drain the air accumulators for the diesel generator air dampers, a complete walkdown of the Instrument Air System was conducted to ensure that our blowdown program did include all components off the Instrument Air System'below the 1025' level of the auxiliary building. A number of components were identified and blown down again with no indication of moisture identified. The air accumulator draining program was also expanded _ to include both non-safety related and safety related accumulators with no water being found in the safety related accumulators during this second draining evolution, and small. volumes (6 ounces or less) of water found in 8 of the 24 non-safety related air accumulators.
Based upon the programs em)loyed to date, OPPD is confident that water has been effectively removed from tie Instrument Air System and presents no hazard to safe operation of the Fort Calhoun Station. However, there remains a concern about the long term effects of residue in the system which could have an effect on the operability of components supplied by the Instrument Air System.
Accordingly, we have implemented a broad spectrum program to address this longer term concern and the' elements of this program are provided below.
In that the failure of the damper for Diesel Generator No. 2 was caused by residue left from the system being wetted, OPPD initiated a program to teardown the air exposed elements of a number of components to further evaluate the potential impact on plant components. The components included in this disassembly inspection program were selected to provide a sampling of each i
component type and make that relies on instrument air for operation and which could be disassembled within the constraints of operational considerations.
This total ;ampling of 47 components, of which 37 are complete to date, has
' demonstrated that components interfacing with instrument air have not been adversely effected by either water exposure or the potential exposure to higher humidity and/or water vapor Section IX provides a more detailed discussion of the results of these inspections.
Another element of our program to address the longer term impact of the water intrusion has been focused on upgrading the quality of the air being provided to the Instrument Air System. One of the key elements to ensuring that those components interfacing or relying on instrument air continue to have a high level of reliability is the cleanliness and dryness of the air provided to those components.
Shortly after the September 23 diesel generator failure the desiccant in the air dryers was replaced to provide dryer air to the system.
In addition, two separate consultants were contracted to evaluate the performance of the Fort Calhoun Station Instrument Air System, and both have recommended a number of longer term corrective measures to improve overall air quality.
In conjunction with this evaluation, OPPD has purchased new dew point monitoring equipment and has implemented a program of regular dew point monitoring and particulate monitoring of the air system.
This program, in conjunction with implementation of those recommendations by the consultants, will'further ensure that longer term impact of the short term exposure to high humidity will not have an impact on the Instrument Air System.
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- w rf LSection[III(Continued)1 I
i
. A third element of our long! erm-corrective action program is the emphasis t
placed on increased inservice testing of air operated valves.
The intent of m
this' increased emphasis is to provide earlier indication of potential-degradation effects that may have been caused by the introduction of water or
-water, vapor into the system. Valves that were stroke time tested on a
. quarterly basis as part of our inservice inspection program are now being j
tested;on a monthly basis. An additional ~36 valves, both safety and non-safety related,ihave been~ included inla special stroke time testing program to be-performed on _a monthly? basis. lThis~ set of 36 valves is made up primarily of i
~
.those valves' not in the IST program which were known to have exhibited water i
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during the second phase blowdowns conducted in early July.
In addition'to the d
regular,IST and the special stroke time; testing program, a re-evaluation of our 1
ilST program was' conducted, and 'approximately 40 more valves will be added to l
thet formal IST program and most will be tested on a monthly basis also. Thus, OPPD has in place a. testing program that includes stroke time testing for a majority'of.those valves known to have been wetted plus a good. sampling of valves >outside the wetted region such that any indication of. increasing stroke
-times should give_ us preliminary indication of potential failures occurring.
To date, we have seen no indication from this program that degradation of
)
components supplied by instrument air is occurring.
Increased frequency of
' valve cycling and measurement of dew point temperatures will continue until
- baseline dataLjustifies an appropriate reduction in frequency or sample size.
Other corrective actions taken to date and completed are as follows:
lA; Pre-job. briefings are held prior to performing a surveillance test which
[
has a period greater _than quarterly.
j B.
_0 PPD'has' identified pressurized connections between the Instrument Air System and other potentially wetted systems and has isolated these j
connections.
-C.
'0 PPD has initiated a procedure change to MP-FP-7 to ensure check valves b
.are inspected and are operable when the doluge valve is reset to ensure
. water does-not. enter the plant air system.
n D.
.A revision to A0P-17 has been initiated'to address:
I L
1.
Operator concerns on previous procedure revisions.
N 2.
Provision of concise and accurate information.
3.
Consistency between the installed system and the A0P.
This procedure will be upgraded in accordance with the procedure 7
writer's guide within 90 days of issuance of the writer's guide.
The various programs implemented and/or being implemented in the near future provide a high level of confidence that the Instrument Air System and its components will~ continue _to function as designed. Although some facets of the programs discussed above have yet to be implemented, all components that rely i
E III-4
i b
i Section III (Continued) l on instrument air for operation are operable. The programs we have in place will ensure early detection of any potential future degradation of components interfacing _with the Instrument Air System. We believe that the improvements i
of the programs that we will continue to implement will further our goal to l
-achieve excellence in the operation of the Instrument Air System.
l l
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[, i SECTION IV LCONCLUSION SUPPORTING SAFE OPERATIONS The assessment of water. ingress and corrective actions, both completed and in
~
progress,. demonstrate that.. water has been effectively removed from the Instrument Air. System and presents no further hazards to safe operation of the Fort Calhoun Station, k'i
' Further, the' amounts and ' consequences of residue left as a result of water
- entry into.the system and/or the effects of high humidity or water _ vapor carryover has been assessed through system component inspections.and operator teardowns. The residue also presents no hazards to safe operation, nor do the consequences-associated with. higher humidity or water vapor carryover. The continued. valve cycling program and operator teardowns will detect any long 7-term effects of residue or residual water.
1 44, IV-1
y 3
u SECTION'V_
- g f,
PROGRAMS TO DEMONSTRATE CONTINVED SAFE OPERATION
. Actions havefbeen, initiated'to. continue monitoring;the status of air operated va'1ves and ' insure that quality air. is supplied at the Fort-Calhoun Station.
LThe'se include: s A.i. Contin'ed dew point measurements. : Selective representative system wide u
monitoring pointst will be checked weekly until-a. baseline of data for these g
(points,is' complete. Then, based upon.the baseline measurements, a sampling l
'- program will, be revised.as necessary to assure a continuing supply of air l
1 with a dew. point-below -20*F throughout the system.
!B. : Continued valve stroke ' time testing at increased frequency to assure valve operability,and detect long term consequences of water' intrusion into the
" Instrument 1 Air System.
C.
Continuation 1of the operator teardown program, to identify existence of any j
?long; term consequences' caused by the July 6,1987, of water intrusion into l
- the1 Instrument Air' System, i
1 i
L 4.
b.
l
[
t i
1^
k
'(s V-1
_.____m_______
SECTION VI OTHER SPECIFIC CORRECTIVE ACTIONS PLANNED OR IN PROGRESS The following is a description of-specific corrective actions associated with the July 6, 1987 water intrusion event. These are planned or in progress and will be completed to resolve Instrument Air System issues.
i' A.
Appraisal of Nuclear Operations An independent appraisal of OPPD's nuclear operations by a qualified, independent firm will be conducted. This appraisal is directed towards improvements in safety of plant operations and compliance with NRC 1
regulations, leading to excellence in operations.
I L'
'This appraisal will review and develop recommendations as necessary in at least the following areas:
Organizational responsibilities a
Management controls and effectiveness a
Staffing levels a
a Communications Safety review process a
Plant operating practices a
Corporate operating practices a
Personnel motivation and discipline a
Our understanding of regulatory and administrative requirements a
Adequacy of improvements to make lasting changes a
The NRC will be fully informed of this activity as it proceeds.
The independent appraiser will providc a report to a review board comprised I
of:
OPPD Board's Nuclear Oversight Committee Chairman a
Senior Vice President Consultant interviews will take place November 23 & 24, 1987 The plan for the appraisal will be completed by Dece6ber 31,1987, and the appraisal will be completed by June 1,1988, to result in long term improvements.
This appraisal is a very significant commitment by 0 PPD.
B.
Design Review of the Instrument Air System OPPD is committed to developing design basis documents for selected plant systems.
The scope of this project will include assessment of Instrument Air System against industry experience and consider necessary upgrades.
This project is scheduled to be completed by June of 1988.
VI-1 u_
j i;
(
l
!Section VI (Continued) l k
- C'.
' System Functional Inspection on the Instrument Air Systems
'0 PPD will complete' a system functional inspection (SFI) to confirm operational readiness and design adequacy.
The SFI will cover areas such as maintenance, testing,. and training and will be completed by January 15, 1988.
.D.
. Upgrade Operating Procedures on Instrument Air System 3
c
'0 PPD ~will review and upgrade the operating procedures on instrument air to
+-
l assure that the operators.are.provided with clear, concise and user friendly procedures. A review of the operating procedures will be completed by January 31, 1988.
E.
A filter will. be added upstream of air operators that currently do not have
.inline filters.
Valve operators with regulators already have such filters.
This action will;be completed prior to startup from the 1988 Refueling Outage.
Safety Sig' ificance of Event and Deportability Evaluation F.
n OPPD will review and upgrade the reporting process and development of an investigation team.and.a procedure for the team.
Findings of the r
investigation. team will:be reviewed by the PRC.
These actions will be completed by December 31, 1987.
,G.
Common' Mode Failure Consideration Engineering procedures will be revised by December 1, 1987 to assure that modifications! formally address. potential common mode failures, including b
combined operator, procedural or equipment deficiencies.
H.
Equipment Operated by Plant Workers 1
OPPD'will review and improve existing guidelines for the limited situations where plant workers, other than operators, utilize equipment to perform l
their work function,.e.g. chemists drawing samples or I&C technicians
. operating instrun:ent valves on instruments being maintained. An upgraded interim policy will~ be developed by December 15, 1987. A complete revision to existing policies will be completed by February 1,1988.
e
- I.
Equipment Tagout. Procedure Upgrade i
Review. existing administrative procedures related to the routine Instrument n
- Air. System lineup and assure that Instrument Air System components are
- appropriately tagged.
Should this review indicate that an upgrade in administrative procedures or the field tagging is appropriate, corrective actions will be taken.
Review and upgrade will be completed by February 29, 1988.
i VI-2
.SectionVIl(Continued)
J.
Safety Consciousness and Procedure Compliance
)
l In order to communicate management expectations and assess / ensure employee commitment towards improvement of safety awareness and compliance, management will conduct small group meetings with all available workers by January 31,.1988.
Following this initial communication session, general
. employee training will' be upgraded to maintain continual awareness of
. management requirements on safety. awareness and procedural compliance.
K.
, Justification for Continued Operation (JC0) Approval Process OPPD will develop formal guidance which will include a notification of the NRC accompanied by a Licensee Event Report should a JC0 be utilized. A
. policy will be issued requiring the JC0 be approved by the PRC and the SARC.
In' addition, training will be upgraded for personnel preparing and i
. reviewing JC0 packages.
This is scheduled to be completed by March 1, 1988.
L. ' Lesson Plans to include Unique System Features Lesson plans will continue to be upgraded for operator training so that unique system features are identified as part of the normal lesson plan revision process.
'M.
Assignment of. System Engineer OPPD has assigned one experienced individual the responsibility of i
coordinating design changes, operations, maintenance, testing, performance trending, and other aspects of the Instrument Air System.
N.
Field Review of the Instrument' Air System by Consultants
'Two consultants have independently reviewed the Instrument Air System and assessed its maintenance, operation, and air quality.
Recommendations from these consultants are being implemented and factored into an upgrade of the preventive maintenance program for the system.
O.
Cycling of ISI Valves The ISI val'ves which cannot be cycled during power operation will be cycled during the next scheduled or forced cold shutdown in excess of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
I P.
Removal of Tie Between Fire Protection and Plant Air System OPPD has identified pressurized connections between the Instrument Air System and other potentially wetted and pressurized systems.
These connections have been eliminated.
In one case, the plant air system was substituted for the Instrument Air System. A modification will be expedited to permanently remove the connection between the fire protection and plant air system.
VI-3 1
d o')
SECTION VII
SUMMARY
OF INSERVICE TESTING PROGRAM ENHANCEMENTS Prior to the IST inspection conducted by the NRC onsite on October 14-15, 1987, the ISI Program included 229 valves,. including air operated, motor operated, manual, check, and safety / relief valves.
The audit resulted in the planned addition of.many valves which were deemed to have a specific safety function as defined by the ASME Section XI code. The instrument air problem initiated reviews' of the safety function of air operated valves and led to the planned
- E
/
addition to the-ISI Program of other valves. Some of these were to have been added previously as a result of the ISI audit in October.
During the October IST Audit, a schedule was established for submittal and review of the revised ISI Program. OPPD will maintain the agreed upon schedule with the inclusion of valves related to the instrument air problem.
The
. revised ISI Program will be submitted to the NRC by December 15, 1987.
It is our understanding.that EG&G will deliver a TER to the NRC within an additional 30 days and the NRC is scheduled to issue an SER by March 1, 1988.
In addition,.five air operated dampers with specific safety functions will be tested for operability in accordance with ASME Section XI frequencies and
-acceptance criteria, but are not considered to be within the scope of the ISI Program.
They will be tested in accordance with Preventive Maintenance or Surveillance Test Programs.
The revised ISI Program to be submitted will incorporate the above changes and will specifically identify valves proposed for inclusion into the Fort Calhoun ISI Program.
VII-1 l
I
mg 7= 7,
J 3>s
, y; O
SECTION VIII
' SEISMIC CONCERNS LSEISMIC'0 VILIFICATION ISSUE o
[<
i fWill the. safety related.(CQE) air accumulator / tubing combinations-(AA/T/C)
J survive a seismic event without loss of safety functions?
V
- BACKGROUND l1'. 1 Seismic Design Basis for Fort Calhoun Station is defined.in USAR Appendix i
F.
Page F 1 of. Appendix F provides a listing of' systems which were s
required to be seismically designed.
^
.2.. Seismic Design Criteria.for accumulators is not clearly-stated in Appendix
' F.
However, accumulators which are required to perform safety functions
.should have been seismic' ally ' designed.
1
- 3 1 Documentation
- Documentation confirming seismic adequacy of accumulators l
installed prior to 1985 is not traceable.
' RESOLUT10N..
I
- 1.. For most.recent. installations (YCV-1045A, YCV-10458, HCV-385, and HCV-386)-
we have documented calculations which confirm that these accumulators were l
designed in accordance with the design criteria outlined above.
L.
2.
Seismic design of.the remaining safety related accumulators has been judged
{
-to:be adequate based on:
.a.
Field verification of all accessible safety related air accumulators
'and tubing combinations.
(HCV-238 and 239 are the only exceptions which ycre not inspected).
b..
Bounding calculations / evaluation will be issued under separate cover.
CONCLUSION
- The results of our field verifications, bounding calculations and engineering evaluat. ion demonstrate a high level of confidence that the safety-related air accumulator / tubing combinations will survive a seismic event.
' FUTURE ACTIONS.
7, L OPPD plans to continue this work and, if required, will re-create detailed calculations'for each individual accumulator installation and add any L
additional restraints under OPPD's resolution of USI-A-46.
LDISCUSSION ON CALCULATIONS lThe NRC representatives had several questions with regard to seismic calculations and to resolve these questions, OPPD agreed to submit copies of these calculations for review by November 20, 1987.
They will sent under separate cover.
VIII-1
SECTidNVIII'(Continued)
. The NRC also inquired about the seismic qualification of valves serviced by
-these accumulators and OPPD agreed to provide what information is available by November 27, 1987. This information will include OPPD's plan for resolution of seismic issues with respect to these valves.
i I
5' 4
VIII-2
e g y
('
c LSECTION IX-
~
SUMMARY
OF MEETING WITH NRC
[Q. o 2N ' 4 Pertainino to.
y, 4
j Instrument Air System Incident' i
E Held November 13. 1987 in Bethesda. Maryland.
p The~fo'llowing.is a' summary of information presented during the November 13, t1987, meeting between OPPD and the NRC.
~'
- Fort Calhoun started operation in-1973, and to date we have been a safe and successful operation.
OPPD isicommitted to the safe operation of Fort Calhoun. The 0 PPD Board 'of Directors and Management have the corporate goal k.
and financial commitment to safe operation of Fort.Calhoun Station.
- Improvement; Programs.which will-result in safety improvements in progress
' include:
4 Site Facilities-(Training Center; new maintenance shops) a 4 g,
- ~
a:
. Simulator - delivery.~ February,1990
- Staffing increases
'379 in NPD; Corporate total. of over 450 m
P
- m' Design Basis Reconstitution for Plant Systems W
Complete procedure review and rewrite m
mL Accreditation-of. training L
~ evaluation and assistance from INP0 Improvement in Maintenance through INP0's MART Process - Self e
ly,
The. incident occurring on July 6, 1987, which resulted in water in the P
' Instrument Air System, occurred dt.e to a combination of design deficiencies, procedure deficiencies, and. training deficiencies.
After the water entered the system, all actions taken were not conservative.
P1' nt operations personnel were confident that the best course to take was o
's.
a
, steady operation ~whilt water was removed from the systrm.
This has been determined not,to have been conservative.
Reporting (internally and to NRC) was not up to normal standards.
m.
Testing and checking was not timely; a controlled shutdown should have been m
tinitiated to remove water from the air system.
LWe are confident that our plant is being operated safely at this time and will
- describe why we'have this confidence.
1 However, this incident demonstrates that all operations at the plant are not as we desire, and as they will be.
I i
IX-1 i
m __ _ _ - _
Section IX (Continued) l The incident has been thoroughly investigated to ensure that we know what happened, why, and what we are going to do.
Several special corrective actions are in progress. Among the most significant are:
1.
System functional inspection of the Instrument Air System 2.
Independent appraisal of OPPD's nuclear operations by a qualified, independent firm. This appraisal is directed towards improvements in safety of plant operations and compliance with NRC regulations, leading to excellence in operations.
This appraisal will review and develop recommendations as necessary in at least the following areas:
Organizational responsibilities m
Management controls and effectiveness a
Staffing levels a
a Communications Safety review process a
Plant operating practices a
Corporate operating practices a
Personnel motivation and discipline a
Our understanding of regulatory and administrative requirements a
Adequacy of improvements to make lasting changes a
NRC will be fully informed, of this activity as it proceeds.
The independent appraiser will provide its report to a review board comprised i
of:
OPPD Board's Nuclear Over::ight Committee Chairman a
m 0 PPD President and CEO e
Senior Vice President Consultant interviews will take place November 23 & 24, 1987 The plan for the appraisal will be completed by December 31, 1987, and the appraisal will be completed by June 1,1988, to result in long term improvements.
This appraisal is a very significant commitment by 0 PPD.
IX-2
n Section IX (Continued)
CURRENT OPERATIONAL STATUS Summary of July 6.1987 Event On July 6,-'1987 an intrusion of water to the Instrument Air System at Fort Calhoun Station occurred. The. source of this water was a connection between the Instrument Air System and the fire protection system at Fort Calhoun Station. Water intrusion occurred during performance of a surveillance test y
which required the wetting of normally dry fire protection piping located in L
the Diesel Generator Room with clarified water. The system was a dry pipe L
system to protect agair,st freezing. The method of holding the deluge valve closed was the instrument air pressure supplied by an air maintenance device and an instrument air line to the fire protection header in the diesel generator room. When the fire system was wetted, water flowed past two check valves into the Instrument Air System for a limited amount of time.
It is important to establish the extent of the ingress of water into the Instrument Air System.
-The water entrainment diagram (Figure IX-7) shows the hydraulics and mechanism of transport of the water in the Instrument Air System. There are several mediums of flow in these pipes.
There is air, entrained water droplets, water vapor and liquid water.
Due to the physical configuration of the piping, the majority of the entrained water' droplets were carried upward to our diesel 1
generator dampers. This is important because later on September 23, 1987 there was a failure of a radiator exhaust damper to open on Diesel Generator No. 2 causing the diesel to overheat and trip during a surveillance test. Water i
carried by.other methods of transport travelled down into the main air header where entrained water droplets went to the equipment utilizing the majority of the air in the air system.
Some liquid water flowed down the pipe into the first downstream pipe exiting on the bottom side of the main header. This was verified by. inspections. The first connection off of the bottom of the main heades goes to a set of valves in which the majority of the water was found.
Several other valves where water was found are high air usage valves such as positioners, explaining why the entrained water droplets were carried in that direction.
Validation of 1025' Elevation Assumotion At this point it is necessary to validate what has come to be known as the 1025' MSL elevation assumption as an upper limit for entrained water or liquid water intrusion.
This level is the level in our Auxiliary Building above sea level where it is believed that no entrained water or liquid water entered.
The methods for the validation of this 1025' condition were based on the initial blowdowns of the intake structure and the turbine room which indicated no water, and initial blowdowns of valves above the 1025' level in our Auxiliary Building, again indicating no water. The results of many inspections of' valve operators have supported this 1025' assumption in that no water or degradation has been found above the 1025' level.
In addition, water was confirmed to be confined to the Auxiliary Building.
Of particular importance to the 1025' level assumption is that the instrument air line for containment crosses over above the 1025' level and penetrates the containment.
To further validate that no entrained water or liquid water got into containment, several valves were blowndown at various levels of containment and again, no water was observed.
IX-3 i
[
K.
M t
Siction.IX(Continued) a.
p
~ At.this point in the presentation, a detailed wall chart was presented which I
L showed the location of'the valves in the Auxiliary Building as well as in
. Containment. -The CQE.1ist, which for Fort Calhoun Station signifies safety n
related equipment, contains. approximately five hundred valves and components that are important to the' operation of Fort Calhoun Station with respect to preventing or mitigating an accident. A subset of that group are the air operated. valves which are required to be in, or 'go to, a position that would
, mitigate a USAR,LChapter 14 event. This list (Table IX-1) has been independently verified. OPPD has initiated blowdowns, cyclings, normal
' operational. monitoring, and corrective maintenance which encompasses the CQE listLin its entirety. Special attention has been focused on the subset of air i
^ operated valves (Table IX-1) which are required to operate to mitigate a 1 Chapter:14 accident analysis.
l First. and foremost, the quality of the Instrument Air System at Fort Calhoun
/'
. Station is currently in compliance with specifications.
The dew point of the q
instrument air-is.approximately -55'F and particulate and hydrocarbons are
.zero..As a part of the dew point program, OPPD has instituted an extensive dew point monitoring' program _with a total of thirteen points. The distribution of sampling locations (as indicated by a drawing given in the meeting) shows that many points have been sampled in the plant at the point of delivery of instrument air to the components. OPPD has verified that the delivered air is
[
v at the.-50*F toL-55'F dew point range, which also indicates that there is no pick up.of water vapor as the air goes through the piping of the system.
Another key part of our corrective action program is an extensive valve cycling program...In order to more closely monitor the performance of the valves which may have.been wetted, those valves that are required to be stroke time tested quarterly in accordance 'with the NRC approved ISI plan are now being tested
-monthly.
In addition, thirty-eight non-CQE valves which are not normally part of our IST program have been added to the list and a baseline time will be established. for these valves and then monitored monthly as a further sampling
'of different types of. valves and valve operators to monitor for degradation. A key part of..this discussion on valves revolves around the valve configuration at Fort Calhoun Station.
(Figure IX-6).
Normal configuration at Fort Calhoun l Station for an air operated valve is to have a regulator, then an operating solenoid and then the valve operator itself.
The importance of this regulator can be seen from the actual regulator.
(An actual regulator was opened at this time and the filter was pointed out). The filter in the regulator is a two micron: filter which provides refiltering capability for the component or solenoid to.be operated. Over two-thirds of the valves on the critical valve
. list have regulators with prefilters installed.
Again, this configuration is key in eliminating any particulate ingress into the individual operating component.. A group of valves. have been selected for a detailed inspection and teardown -of the' operator, the solenoid and the regulator.
The basis for selecting these. valves was to determine the extent of water, water vapor and residue-intrusion at Fort Calhoun Station.
This was to be done laterally as well as by elevation level, to cover all types of operators in use at Fort
'Calhoun Station, and to bias the sample of valves toward valves which may have
'been wetted.
Results of the valve operator, solenoid and regulator inspections have: indicated no problems and no inoperable valves.
4 IX-4 w _- _ _
.Section IX.(Continued) i During this-inspection of the regulators, a powdery residue was found in some of the bowls on certain regulators. A survey of the vendors of the operators indicated that residue water in the operator would not affect valve operation.
It-should' also be noted that the solenoids used at Fort Calhoun Station are ASCO solenoids-and are rated for use in water, inert gas or air. The results of 'this inspection support the belief that no inoperable valves will exist even though a residual amount of water may be found in some of the operators such as a
the.large,Bettis operators. A powder-like residue, of approximately a quarter of a teaspoon per regulator bowl, had been found in some regulators. A chemical analysis.of this residue is shown in Figure IX-8.
The first four entries indicate the valve numbers for the diesel generator damper valves.
Figure IX-8 indicates the chemical make-up of silica gel and the last entry is a1 valve located in the basement of our Auxiliary Building where residue was found.
Of obvious concern was that the residue found was from desiccant, leaking by the main after filter on the air dryer. As can be seen, the residue i
in the bowls does not appear to be from the silica gel. We believe it to be the products of fifteen years of operation in a high pressure environment.
(Pictures of the samples and samples of the material were provided during the meeting).
Another part of our testing and inspection program is accumulator and accumulator check valve inspections. Nine out of nine check valves in the
' wetted area have been successfully tested and have passed acceptance criteria.
Accumulators.below the 1025' elevation have been inspected and drained of any water found.
The largest quantity of water was found in the valves above the diesel generator radiator exhaust dempers with the second largest quantity being found in the SIRWT suction valves. All valves with the exception of the diesel generator valves have'been verified by our Engineering Department to have enough volume to operate with the water found as a result of the water ingress.. One area we again looked at during the week of November 7, 1987 was the DG-1 and DG-2 air dampers.
This reinspection was initiated to investigate if additional residue had built up. At this point, it is important to clarify that the original material, although many rumors surfaced to the contrary, was limelike and gummy in nature.
It has been rumored that the original material was so hard it had to be drilled out.
Detailed interviews with the technician have indicated that the material was not drilled out, however, a drill bit was used by hand (not attached to a drill motor) to clean the orifice.
It is important now to discuss the significance of the DG-1 and DG-2 dampers as they differ from other valve component installations at Fort Calhoun Station.
These valves (Figure IX-9) use a pilot valve which has a very small pinhole orifice in the top to port air.
This is the critical link in the valve component configuration and as you can see from this valve, there is no prefilter with a very small pinhole port which can become plugged if air blows by seating rings on the pilot valve.
j One-last significant inspection that was conducted was the reinspection of HCV-385 and 386.
These are located in the lower level of the Auxiliary Building and are.the recirculation isolation valves for the SI pumps.
A
(
regulator was installed last May during the refueling outage.on these valves.
OPPD disassembled the regulators currently on HCV-385 and 386.
No residue was IX-5
r i
n 9
Section IXi(Continued);
o j
N, found Lin the bowls of either.of these regulators, supporting the belief that the. residue was the' product of fifteen years of operation and not carried in during water ingress.
Both HCV-385 and 386 were wetted during the water
~ ingress in July.
The corrective: action' plan that we have developed to continue the monitoring of the4 status-'ofiair. operator valves at Fort Calhoun Station and insure that a quality 'airnsystem is supplied at Fort Calhoun Station is as follows:
+
(1.
Upgrade;the' Instrument' Air Dryer System to include a' smaller micron
-after-filter.
2..
Revise.the preventative. maintenance schedule for the instrument air dryer.
3.-
Provide more in-depth plant operator training.
4.
Continue. preventative maintenance including continued valve, solenoid and (regulator operator teardown as appropriate. The scope of these teardowns, regulator inspections and solenoid inspections will be determined by the results:of previous teardowns.
'5.t Month 1y' preventative maintenance'on the diesel generator dampers.
- 6.
Proceed'withL planned' modifications to install prefilters, such as in the regulator, on all. air components.
'7.. Replace the diesel generator air dampers with an air damper utilizing a
- 4
?different' type of operating control mechanism which will not be dependent on)a small ported orifice.
4 In summary,- the key elements of our program are:
a continued dew point measurement program and maintaining the dew point low; improving our valve l component-configuration to include a filter; the current valve cycling program; and the current operator teardown program. Water has been removed from the
- Instrument Air System piping. An insignificant amount of water has been found inLsome valve operators disassembled to date. A small amount of water will not and has not precluded operation of the valves. The continued valve cycling program and operator teardown program will detect any long term effects of any
- remaining water.
The previous and continued valve cycling program combined with the previous and continued operator teardowns will detect any long term affects of any remaining residual water. This program of operator monitoring E as!well as operator teardown precludes the possibility of common mode failure
= as a result of the water intrusion event on July 6,1987.
~
IX-6 r- _- -
l l
f l
Section IX-(Continued)
SAFETY EVALUATION Evaluations were undertaken to better understand the safety significance of the water intrusion into the Instrument Air System at Fort Calhoun. The objective of these evaluations were to completely analyze the event and to identify actions which would improve our ability to prevent and to respond to similar events in the future. An ' evaluation of the safety status of the plant with respect to the Updated Safety Analysis Report was conducted for the July 6
. event.
Conformance with the Technical Specifications during the event was evaluated. The -ability of the plant to successfully respond to transients
-during the July 6 event was evaluated through an assessment of the capability
-to implement the Emergency Operating Procedures.
Finally, an evaluation of the implementation of the Emergency Plan was conducted.
An' independent evaluation of the safety significance of the July 6, 1987, event with respect to the Updated Safety Analysis Rtport was conducted by a consul-tant under contract to 0 PPD. The event was reviewed against the criteria of 10 CFR 50.59. The results of the analysis are that the event satisfies the three (3) criteria for an unreviewed safety question.
Specifically, the consequences of an event previously analyzed in the USAR were increased.
A malfunction of a different type than previously evaluated in the USAR was created and the margin of safety as defined in the Technical Specifications was reduced.
In addition, it was. determined that the event was reportable under 10 CFR 50.72 and 10 CFR 50.73.
To evaluate compliance with the Fort Calhoun Station Technical Specifications, the ability of the plant to respond to transients on July 6, and to consider
' implementation of the Emergency Plan during the event, an evaluation team was assembled. This team consisted of safety analysis engineers familiar with the transient response and Safety Analysis requirements of Fort Calhoun Station and NRC licensed Senior Reactor Operators, both staff and operations personnel.
The team first considered the conformance with the Technical Specifications.
Conformance was judged by determining the compliance with the Limiting Condi-tions for Operations in the Fort Calhoun Technical Specifications.
The team attempted to place themselves in the position of determining the status of the LC0's by taking a time snapshot at approximately 1200 on July 6, 1987.
For the purposes of the evaluation, the team assumed that the operability of the various components associated with the Instrument Air System was not assured due to the introduction of a known failure causing substance into the system.
In reviewing the LCO's, the team concluded that many of the LC0's could have been verified by testing at power.
However, some of the LCO's could not have been verified in this manner, such as testing of the main steam isolation valves.
Therefore, the team felt that the appropriate action would have been to initiate a power reduction to achieve hot shutdown in the next six hours in accordance with Technical Specification 2.01(2).
The team felt that during the shutdown process testing would have to be performed on the steam dump and bypass system and the bypass feedwater valves to assure that the plant could be safely put into hot shutdown. The team concluded that the information that no water had been found above the 1025' level during the afternoon of IX-7 o
_________J
l Section IX'(Continued)
July 6 would have provided sufficient evidence that the plant could be safely i
put into hot shutdown. The team also concluded that there may have been enough 1
information available on the' afternoon of July 6 to conclude that the LC0's were satisfied and it was no longer necessary to operate under Technical Specification 2.01(2).
The team-also concluded that sufficient information would have been available on July 6 to preclude entering.the clause of Technical Specification 2.01(2) requiring cold shutdown.
In analyzing the event with respect to Technical Specifications, the team believed that the plant had focused on the limited number of component failures rather than the potential for failures of a large number of components due to the water introduction into the Instrument Air System.
The team next considered the physical capabilities of the plant to respond to postulated transients if they had~ occurred during the instrument air intrusion on July 6, 1987.
The team evaluated the capability of the plant to respond to postulated transients by evaluating the plant's capability to successfully implement the safety functions of the Emergency Operating Procedures.
The team initially assumed that all air operated components below the 1025' level of auxiliary building were inoperable (i.e., they had failed in their "as is" position or were incapable of fulfilling their safety functions).
This assumption was based upon results of valve blowdown tests.
Rather than look at the plant's capability to respond to specific transients, the team focused on the ability to implement the Emergency Operating Procedures to provide a i
bounding evaluation of the plant's response to transients.
The team de' termined that all safety functions could be maintained if a diesel generator is operable and the Safety Injection Refueling Water Tank level instrumentation is operable. A diesel generator must be operable to provide I
motive power to the High Pressure Safety Injection pumps which would fulfill the core inventory safety function in case of a primary or secondary side pipe rupture.
In addition, the SIWRT level instrument must be operable to assure that the suction valves from the SIWRT are properly positioned to assure suction is available to the safety injection pumps.
The team believed that at least one (1) diesel was operable because DG-1 was successfully operated on July 8, 1987 and both diesels successfully completed their surveillance in July and August, 1987.
The SIWRT level instrumentation was known to be operable from control room observations during July 6,1987, and at no time during the day did the instrumentation show any indications of inoperability.
In addition, the team concluded that even if the water had not been drained from the instrument air lines in the diesel generator room, there was sufficient air in the accumulator, based on the volume of water found in the
' DG-1 accumulator, to successfully open the outlet damper (radiator) on the diesel generator.
IX-8 1
p l
Section IX (Continued)
Calculations have shown that a sufficient volume of air to operate the air motor twice, even with the accumulator half full of water.
There is no F
evidence to indicate that the level of water in the accumulator ever exceeded hal f. full. The vendor of the air motor has confirmed that the air motor will operate with water as the hydraulic fluid rather than air.
The team recognized that it is impossible to definitively prove or disprove the operability. of DG-I on July 6,1987, assuming the water had not been drained from the. lines and a demand had been-placed on it for operation. The team felt there was a high probability of operability, but the team further assessed the Emergency Operating Procedures for the case of failure of both diesel generators.
The team concluded that all safety functions, with exception of the core inventory Safety Function which is necessary for primary and secondary
' site pipe ruptures,- could be maintained for all other events.
This includes L
the station blackout event. The primary success path for these various events is in Emergency Operating Procedure No. 2 which identifies a means to utilize the turbine driven auxiliary feedwater pump in conjunction with the manual alignment of the auxiliary feedwater system to the main feedwater header to remove residual heat through the steam generators and maintain the unit in hot
. shutdown. Calculations have shown that sufficient time, approximately 30 minutes, is available to manually initiate water to the steam generators in case of a station blackout.
The team also evaluated the plant scram procedure (E0P-1) and determined that the plant could be safely placed in hot shutdown at all times.
. Finally, the team assessed the possibility of implementing the Emergency Plan i
during the~ July 6 event.
In reviewing current Abnormal Operating Procedures and Emergency Plan Implementing Procedures, the team determined that a declara-tion of NOTIFICATION Of UNUSUAL EVENT was not required by the procedures.
In addition, the team noted that the procedures did not lead personnel to consider the Emergency Plan if an Abnormal Operating Procedure had been implemented.
The team concluded that NOTIFICATION OF VNUSUAL EVENT would have been a prudent
' activity primarily because this is a quick means to augment the onsite staff with offsite personnel to provide additional expertise to evaluate and respond to the event.
The review of the July 6,1987, intrusion of water in the Instrument Air System has identified several areas where improvement is necessary.
There is a need for improved safety consciousness and procedural compliance among 0 PPD person-nel.
To ensure this happens, OPPD has previously committed to individual q
meetings between Division management and employees where safety consciousness 1
and procedural compliance will be discussed.
During these meetings, management will obtain individual commitments from personnel for improved safety conscious-ness and procedural compliance. This commitment will be reinforced through our annual General Employee Training.
The effectiveness of this training will be ascertained through field observations made by Supervisors and foremen. OPPD has recently conducted field observation training in accordance with an INP0 developed methodology and will train additional personnel in 1988.
IX-9
Section IX'(Continued)
The review team recommended that Abnormal Operating Procedures include refer-ences to the Emergency Plan Implementing Procedures and discussion of possible potential common mode failures. The Emergency Plan implementing procedure needs. to be upgraded for inclusion of common mode failures.
Dusing the review'of this event, the need for a better mechanism for handling
- justifications for continued operation was identified.
OPPD will undertake a
~ thorough review of the basis for justification for continued operations and identify methods by which events can be properly reported and information concerning compliance with the design basis can be transmitted to the NRC.
In addition, OPPD will assure that actions which require temporary operation outside the design basis until components can be fixed will receive thorough Plant Review Committee and Safety and Audit Review Committee review.
The actual mechanism by which water entered the fire protection system has identified a need for increased detail in lesson plans on unique system features..To identify and emphasize _these unique features and include them in lesson plans, personnel in the Training Department have been assigned as system experts to each system to increase the level of knowledge on each system in order to increase the level of detail included in the lesson plans.
The team observed a need for improved event evaluations for safety signifi-cance. To provide this improved event evaluation, OPPD is currently improving the plant' event report system for emphasis on safety significance of events.
In addition,'0 PPD will establish an event investigation team which can be activated by the Plant Manager to provide in-depth investigation of any event at Fort Calhoun Station.
Finally, there is a need for prompt reporting of events to the NRC. The plant event report system is being revised to further emphasize the requirements of 10 CFR 50.72 and 50.73.
Reviews of these requirements have already been conducted with the Shift Technical Advisors.
We believe that these actions will assure better reporting to the NRC of events at Fort Calhoun Station.
IX-10
Section'IX.(Continued) p SPECIFIC CORRECTIVE AND i
PROGRAMMATIC IMPROVEMENT ACTIONS l
.The Omaha Public Power District has. developed a corrective action plan as a l
s result of the water intrusion event at the Fort Calhoun Station on July 6, 1987.' These actions are divided'into two categories:
1.
Specific. corrective actions.
l
'These are items which specifically address issues related to the Instrument Air System and the recent Instrument Air System events.
These items have been or will be completed in a timely marner and essentially encompass instrument air concerns which, when com'leted, will resolve the Instrument p
Air System issues.
2.
Programmatic improvement actions.
These are future actions. intended to be more substantive and wider reaching than the action to resolve specific instrument air issues. Our goal as a
. nuclear utility is to become a future industry leader, respected for our excellence in operation of the Fort Calhoun Station. We view these as programmatic improvements, therefore, long term projects to lead us to our goal.
Figure IX-16 shows specific corrective actions as well as programmatic improvement actions that. are planned by the Omaha Public Power District. The Company is currently evaluating appropriate action in each of these areas.
In accordance with an NRC request to submit the Company's assessment of the July 6 event' and the maintenance and operational corrective actions related to that event in a timely manner, a future submittal will contain a description of action planned under each specific corrective action.
IX-11
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. MANAGEMENT ISSVES
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~ Managementlinitiatives 'were discussed' earlier. Several technical corrective iactions and programmatic?init,iatives have also been discussed. The bottom line
' management issues are-W..m.. %
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' Operational ' Safety
'6 ["
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[
"The' keyLrol's' played by line management, the shift operations crew e
b.'
'.(including the Shift.Technictl Advisor), and the onsite and offsite fjp if safety ' committees;for operational safety have been re-emphasized. A
.'y
'M conservative approach to' plant operational ~ safety is absolutely EA-
.necessary,:and has.been reiterated as our current philosophy.
s N,
ys II.
Sa_fety Evaluations-J The importance of timely' safety; evaluations' for operational events was L
re-emphasized. A new OPPD safety evaluation proceduro has been approved.
U III.
Investigations-4
.The-importance' of fully investigating significant operational events by
)
ithe;11censee'has been stressed. ' Appropriately constituted subcommittees of the onsite or offsite safety review, groups will be utilized as the
~
.L,'
vehicle for these. investigative' efforts.
-~
Notificat' ions
- IV.
.._The:importance of timely NRC notifications, pursuant to 10 CFR 50.72 and h
'l50.73,has'been-re-emphasized.
LN
- L V.
Communications
(
- .n A high priority will tie placed on open and complete communication, both i
within OPPD and with the NRC.
h h
OP' PD has11 earned valuable and important lessons from these events and believe H
we have good actions underway.
Implementation of these actions, along with the abilities'of.our present conscientious work force, will ensure compliance and prevent. recurrence..
4 b
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,1 IX-12 i
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(
f Section IX (Continued)
SUMMARY
OPPD is committed to, safe operation of Fort Calhoun Station. We have i
. thoroughly investigated the event on July 6, 1987 and subsequent events caused by the introduction of water into the Instrument Air System.
These events and the consequences have been analyzed and are known. This investigation has shown that the plant is' safe to operate.
Corrective actions resulting from this incident that have been and will be taken have been defined and scheduled. Among these are changes to maintenance, proceduras, training, and management. OPPD will provide written confirmation of all actions and schedules discussed in the November 13th meeting.
l IX-13 b
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NRC/0 PPD. MEETING s
INSTRUMENT' AIR SYSTEM-i:
u NOVEMBER 13,.1987 sc s
AGENDA Est.
_Section Tonic 3 }'
Presenter Time 11; Opening Remarks W. C. Jones 5 mins g
!II.
' Current Operational Status W._G. Gates 20 mins-
' July 6, 1987 Event / Scope 0 '
'- ' Investigation and Results
' Corrective Action.To Date-
"E Inspections and Maintenance
--1. Basis-for Continued Operation U
,n III.
(Safety Evaluation :(July 6,1987)
J. K. Gasper 15 mins
- u. -
Plant Transient. Response Capability
-n Technical' Specification Implications
.; Emergency Plan Implications'
' Corrective Actions
_ g m
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IV.,
. Specific'Corre'ctive=and Programmatic R. L. Jaworski 10 mins 4
Improvement Actions-m a
V..
' Management' Issues R. L. Andrews 5 mins
' VI.
Summary:
W. C. Jones 5 mins l
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i Fi gure. IX-2
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DC NRC/0PPO MEETING
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INSTRUMENT AIR SYSTEM j
l NOVEMBER.13, 1987 1
BREAKOUT MEETING - AS NECESSARY LSEISMIC'. QUALIFICATION S. K. GAMBHIR 4 JUSTIFICATION FOR CONTINUED OPERATION T. L. PATTERSON e
J. K. GASPER 4
K..C. HOLTHAUS j
IJULY:6. 1987 t-L
- -0ETAILED ACTION / INVESTIGATION / CORRECTIVE ACTIONS T. J. MCIVOR M. R. CORE
- MAINTENANCE M. T. FRANS
' AUGUST'25 _1987 DETAILED ACTION / INVESTIGATION / CORRECTIVE ACTIONS T. J. MCIVOR M. R. CORE
- - MAINTENANCE-M. T. FRANS SEPTEMBER 23,-1987 DETAILED ACTION / INVESTIGATION /CCT.RECTIVE ACTIONS T. J. MCIVOR M. R. CORE MAINTENANCE-M. T. FRANS MATERIAL AND CHEMICAL ASPECTS G. L. ROACH j
ANALYSIS 1
l DEW POINT PARTICULATE COMPOSITION f
)
FOLLOW UP'TO 0900 MEETING J. J. FISICARO i
g OTl!ER ISSUES AS NECESSARY 1
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CURRENT OPERATIONAL STATUS
' AREAS OF DISCUSSION;
'A..'
UNDERSTANDING OF INITIAL' EVENT AND SCOPE
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'. SPECIFIC PROGRAMS AND CURRENT RESULTS
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INSTRUMENT AIR SYSTEM' CURRENT OPERATIONAL STATUS SPECIFICS
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DEW POINT MONITORING PROGRAM'
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VALVE CYCLING-ISI PROGRAM ADDITIONAL ISI PROGRAMS D.
VALVE OPERATOR INSPECTION (NO OPERATORS FOUND TO BE INOPERABL
. VALVE SOLEN 0ID INSPECTION VALVE REGULATOR INSPECTION E.
' CHEMISTRY' DISCUSSION RESULTS AND LIST OF VALVE OPERATOR VEND 0R COMMENTS F.
- ACCUMULATOR'AND ACCUMULATOR CHECK VALVE INSPECTION j
G.-
REINSPECTION'0F DG-1 AND DG-2 AIR DAMPERS H.
REINSPECTION OF 385/386 AND ITS SIGNIFICANCE Figure IX-5
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tS S G' GC C S S ( 2 2 U 3 3 2 2 G ( mI C S 1 1 E f o o y > s s s s s s C t s s e e o e e e e o o e e t N N k t I I Y Y N Y Y Y Y N N Y Y I d e l W s s s s s s s s s s ~ C e e e e e e e e e e Y Y Y Y Y Y Y Y Y Y .y kva i lk OVO s s e e Y Y V man 5 m t e e e i unu 2 A a c n n r o o cio 1 N >T c a m_ e N N-A r A__ s m s s s s o o o o o o o o e a e e e e o o D N N N N N N N N Y S Y Y Y Y N N r f o ot a r r r r r r r r s s r r r r r r er e e e e e e e e i i e e e e e e pe h h h h h h h h t t h h h h h h yp s s s s s s s s t t s s s s s s ) d I i i i i i i i i e e i i i i i i e O_ F F F F F F F F B B F F F F F F u r i t n o c tn ( no ei ) ) t dt C C n ii B B B B B ) ) ) ) ) ( ( e cs ) ) d co ( ( ( ( ( E E i d d d ( ( d l e e e e a AP n n n men n n s n n s s n n s s r e e e e e o e e o o e e o o c p p p p p p p l p A O O O O O O O c O l l p p l l C C O O C C n a e m t a l g ai 'e i mt e e e e t ri l l l l l 1 i os b b b b b d M Nb a a a a a e d d d d X o r r r r r e e o e e e I i i i i i n n s n n n e e e e I W. s s s s t a a a a a p p l p p p o o o o V V V V V O O C O O O l l l l e e C c c C l ta m b r u a e c p g T _ y O h o t n Eu s s s s s s s s s s s s s s s s Om Y d Q e e e e e e e e e e e e e e e e w Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y z A i u qe R r r p p k k o o r r s O O n n t t o o e a a a a t t v v v T T k P r r a a l l l p n W e e r r a V V O r r a R p p e e v e e T I O O p p l l v t t S O O E 1 o o i Q s s s V m h c v v r o l l v v c v I I C i v i l c c c V V i t V V l l . a t l V A A o r r e c l l p V 1 2 s i i R r o o y y i l I c c i s s a a WA l o B p p e e I c I I r r A o s 6 o c 8 s I c c ay R R S e p p _ e I A I I r t t o d i R r r S S B V p c c t n H r r k V B B 8 o o S e e i e e I 8 r t t j j c M y y t t . q o 4 A o r n n r a a l l t A A V f g g z Iv I i v m r r i i s V V s r r 1 cl a p p F F t t t i i P yV y eV e S S e t t e e g g t t R r A B . 3 l e e l l r r el el l t t t 3 3 t l l t t a a r f o f o no s n n u n n u u h h o O I I O O C C A SI SI MI U ( ( t as as is p b b A A _ g V V io n 9 9 9 9 9 1 1 9 9 _ z 6 6 6 6 6 9 0 5 2 2 4 4 5 5 5 5 . n. t_ 9 0 4 a a na a n a 9 0 0 a a n n n n 0 0 4 4 c c c c c c 0 1 1 c c c c c c 1 1 o o o o o o o o o o o o . w l R R R R R C C C-R R R R R R C C _ s t c 1 2 a D A B C D w- : T 2 3 3 3 3 8 9 0 3 3 5 6 4 5 4 5 0 0 0 0 0 3 3 4 8 8 8 8 4 4 6 6 e. ev 4 4 4 4 4 2 2 2 3 3 3 3 3 3 8 8 l V V-V- N-V V-V V V V V N V N m V V a C C C V H H H K C C C C C K C C E K IC H H H I I 1 K I l H I 1 I I I _ 2 Na 1 o 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 - w
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