ML20002D258
| ML20002D258 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/05/1981 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 1-179, IEB-80-24, NUDOCS 8101200185 | |
| Download: ML20002D258 (12) | |
Text
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r TOLEDO
%ms EDISON Docket No. 50-346 n,:.a. : o cm.,
License No. NPF-3 ff.T.7 ' '
me Serial No. 1-179 January 5, 1981 y
12 Mr. James Keppler
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Regional Director, Region III
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Office of Inspection and Enforcement "O
U.S. Nuclear Regulatory Commission 2$
799 Roosevelt Road Glen Ellyn, Illinois 60137
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Dear Mr. Keppler:
This letter is in response to IE Bulletin 80-24 dated November 21, 1980, (Log 1-446) as applicable to Davis-Besse Nuclear Power Station. Attached is Toledo Edison's required 45-Day response to the items of the Bulletin.
As requested by your letter, the following are estimates of the manpower expendi-tures in association with this Bulletin:
Review, Testing, Preparation of Report - 120 manhours Corrective Action
- 40 manhours (projected)
Yours very truly, f
7 RPC/TDM/JWM/lrb Attachments cc: NRC DB-1 Resident Inspector i
Director, NRC Office of Inspection and Enforcement Washington, D. C.
20555 THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652 B8 8101200 \\n d
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r RESPONSE TO 1E BULLETIN 80-24 Docket No. 50-346 Serial No. 1-179 ITEM 1 Provide a summary description of all open* cooling water systems present inside containment.
Your description of the cooling water systems must include:
(a) Mode of operation during routine reactor operation and in response to a LOCA; (b)
Source of water and typical chemical content of water; (c) Materials used in piping and coolers; (d)
Experience with system leakage; (e) History and type of repairs to coolers and piping systems (i.e., replacement, weld, braze, etc.); (f)
Provisions for isolating por-tions of the system inside containment in the event of leakage including vulnerability of those isolation provisions to single failure; (g) Provi-sions for testing isolation velves in accordance with Appendix J to 10 CFR 50 (h)
Instrumentation (pressure, dew point, flow, radiation detection, etc.)
and procedures in place to detect leakage; and (i) Provisions to detect radioactive contamination in service water discharge from containment.
- An Open system utilizes an indefinite volume, such as a river, so that leakage from the system could not be detected by inventory decrease.
In addition, a direct radioactive pathway might exist to outside containment in the event of a LOCA simultaneous with a system leak inside containment.
A ciascd system utilizes a.fixsd, monitored volume such that leakage from the system could be detected from inventory decrease and a second boundary exists to prevent loss of containment integrity as a result of a system leak inside containment.
RESPONSE
Item 1 The Davis-Besse No. I containment (CTMT) vessel contains one open cooling water system referred to as the Service Water System.
One of the functions of the Service Water System is to supply cooling water to various heat ex-The Service Water S' stem contains three pumps changers at the station.
y which take suction from Lake Erie, and supply lake water to the various com-ponents at the station. After the service water passes through:the components, the Service Water is either diverted to the Circulating Water System (Cool-ing Tower) or returned to the lake.
The Service Water System supplies cooling water to one system in containment, the Containment Air Cooler System.
The Containment Air Cooler System consists of three air cooling units, located inside the Containment vessel.
Each consists of a finned tube cooling coil and a' direct driven fan.
The Service Water passes through the tubes of the coolers.
The Containment Air Coolers are designed to remove heat from the Containment atmosphere during normal operation.
During a Loss of Coolant Accident, the Containment Air Cooler System provides cooling of the Containment atmosphere to reduce the pressure build up in the Containment vessel thus reducing the leakage of radioactivity from Containment.
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Risp:nza to'1E Bu11stin 80-24 Dockct N3 50-346' S2rici No,-1-179
RESPONSE
Item lA.
During' routine reactor operation - two Containment Air Coolers are oper-ating (in high speed) and the third Containment Air Cooler is idle in the standby mode. A modulating control valve in the Service Water outlet of each cooler controls the amount of Service Water ficw through the cooler
. regulating the amount of cooling, thus maintaining a desired Containment air temperature.
The normal Service Water flow through each cooler is approximately 1600 gpm.
RESPONSE
Item IB.
The source of water for the Service Water system is Lake Erie.
The typical chemical centent of Lake Eric water is as follows:
Calcium 45 mg/L Magnesium 11 mg/L Sodium 12 mg/L Chloride 22 mg/L Nitrate 12 mg/L Sulfate 37 mg/L Phosphate 1.5 mg/L Silica 2 mg/L Alkalinity as C,CO3 101 mg/L Suspended Solids 131 mg/L Dissolved Solids 225 mg/L Dissolved oxygen 10 mg/L pH 8.1 The Service Water is continuously chlorinated to prevent slime and algae growth in the heat exchangers of the Service Water System.
RESPONSE
Item IC.
All Service Water system piping material located in Containment is carbon steel piping.
The Containment Air Cooler tube material through which the Service Water flows is 90/10 copper nickel alloy; the external fins, clamped to the tubes, are copper.
L
.Re:pon a tb IE Bullctin 80-24 Dock:t N3.'50-346 S:rici No. 1-179
RESPONSE
Item ID&E An investigation to identify experiences of Service Water leakage in Con-tainment, indicated that there is no record of problems with Icakage from either the Service Water system piping in containment or the Containment Air Cooler coils.
As a result, there have been no repairs necessary to be made to the Service Water piping in containment or to the Containment Air Cooler coils.
RESPONSE
Item IF.
Each Containment Air Cooler has a 8" Service Water supply header which enters containment and splits into two - 6" supply lines which supply the Contain-ment Air Cooler with cooling water.
Each Containment Air Cooler has two 6" Service Water return lines which com-bine into one 8" return header, inside Containment, 1 caving Containment as a 8" header (see Figure 1).
In the event of a Service Water System leak inside containment, the Service Water System in containment may be isolated from outside and/or inside containment.
If a Service Water Icak is suspected in either the Service Water piping or Containment Air Cooler, the Service Water supply and return to each Contain-ment Air Cooler may be completely isolated by valves located outside of containment. Containment Air Cooler 1-1 has two valves in series, in both the 8" supply header and 8" return header, which can be closed to isolate Service Water to Containment Air Cooler 1-1.
Containment Air Cooler 1-2, also has two valves in series, in both the 8" supply header and 8" return header, which can be closed to isolate Service Water to Containment Air Cooler 1-2.
Containment Air Cooler 1-3 has three valves in series, in both the 8" supply header and 8" return header, which can be used to isolate Service Water to Containment Air Cooler 1-3.
If the Service Water Icakage is observed to be from a Containment Air Cooler, each Containment Air Cooler has provisions to be isolated locally, inside containment. The two 6" Service Water supply lines and two 6" Service Water return lines each have an isolation valve which can be closed, from inside containment to isolate Service Water to the Containment Air Cooler.
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r Re:pon:2 to IE Bu11stin 80-24 Dock 2t No. 50-346 S rici Ns. 1-179 Since the Service Water supply and return lines to each Containment
-Air Cooler have a minimum of two-valve isolation (outside of contain-ment), a single valve failure should not prevent the isolation of Service Water to the affected component.
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TYPICAL OF CONTAINMENT j
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CONTAINMENT
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l FIGURE 1 Simplified Drawing of Service Water to the Containment Air Coolers w
Docket N3. 50-346 S2rici No. 1-179 f.ESPONSE:
Item IG.
The Containment Air Coolers' Service Water inlet and outlet con-tainment isolation valves are not subject to leakage testing. 10 CFR 50 Appendix J and Technical Specification 3.6.3.1 Table 3.6-2 provides for the exceptiot. from testing of the Containment Air Cooler Service Water. inlet and outlet containment isolation valves.
RESPONSE
Item IH.
Each Containment Air Cooler has a leakage detection system which de-tects an accumulation of water under the Containment Air Cooler.
The leakage detection system consists of a condensate drain pan, lot e.:3 under the Containment Air Cooler which collects condensate or Service Water leakage from the Containment Air Cooler.
When a leakage flow of
> 0.5 gpm is detected an annunciator is received in the control roo.n.
The containment normal sump has two level transmitters, each of which provide the control room with (1) normal sump level indication (f t) and (2) a computer alarm on detection of a high level in the normal sump.
The containment normal sump has two level switches each which activate a control room annunciator and computer alarm on detection of a high level in the normal sump.
The containment normal sump contains two pumps which automatically cycle on/off upon detection of a high water level in the normal sump.
The sump pumps normally cycle on/off at a sump level below that which activates the high level annunciators and computer alarms.
When a sump pump is operating,a computer alarm in the control room is received.
Each sump pump motor has an elapsed time meter located in the auxiliary building which measures the accumulated pumping time for each sump pump.
The pumping time is converted to a flow rate and thus the flow rate from the normal sump is calculated.
An additional method may be used to determine the volume of a signifi-cant amount of water - pumped f rom the sump.
The discharge of the sump pumps normally flows _ into the Miscellaneous Waste Drain Tank (MWDT).
Observation of a level change in the Miscellaneous Waste Drain Tank could be utilized to calculate a large flow rate from the normal sump.
Procedures - The normal sump flow rate is determined once per shif t during the performance of ST 5099.01, Miscellaneous Instrument Shift Check.
The flow rate is currently calculated from the pumping times I
recorded on elapsed time meter for each sump pump.
The calculated flow rate is recorded in a log book in the control room.
Since the normal sump flow rate is calculated by the Surveillance Test approx-imately once every eight hours, any significant increase of leakage in containment would be immediately i.ientified.
R*csponde to IE Bullet in 80-24 Docket No. 50-346 Serici No. 1-179
RESPONSE
Ite,m II.
Service Water discharge from containment combines with the Service-Water discharges f rom other components in the plant and is then mon-itored for radioactivity by an of f-lire ef fluent sampler, RE8432.
The Service Water System discharge is normally used to supply make up water to the Circulating Water System (cooling tower).
If the Ser-vice Water System. discharge is diverted to the lake, the Service Water discharge mixes with approximately 10 to 15 thousand gallons of dilu-tion water. The diluted Service Water discharge is then discharged to the lake af ter being monitored for radiation by an of f-line ef flu-ent sampler (RE8433).
If radioactivity is suspected "in the Service Water discharge f r.0:
containment, provisions exist to sample Service Water discharge from Containment.
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Rzponse to IE Bullctin 80-24 Dockst No. 50-346 S rici NO, 1-179 ITEM 2 For plants with open cooling water systems inside containment take the following actions:
Verify existence or provide redundant means of detecting and promptly a.
alerting control room operators of a significant accumulation of water in containment (including the reactor vessel pit if present).
b.
Verify existence or provide positive means for control room operators to determine flow from contninment sump (s) used to collect and remove water from containment.
c.
Verify or establish at least monthly surveillance procedures, with appropriate operating limitations, to assure plant operators have at least two methods of determining water level in each location where water may accumulate. The surveillance procedures shall assure that at least one method to remove water from each such location is available during power operation.
In the event either the detection or removal systems become inoperable it is recommended that continued power operation be limited to seven days and added surveillance measures be instituted.
d.
Review leakage detection systems and procedures and provide or verify ability to promptly detect water leakage in containment, and to isolate the leaking components or system.
Periodic containment entry to inspect for leakage should be considered.
Beginning within 10 days of the date of this bulletin, whenever the e.
reactor is operating and until the measures described in (a) through (d) above are impicmented, conduct interim surveillance measures. The measures shall include where practical (considering containment atmos-phere and ALARA considerations) a periodic containment inspection or visual surveillance to check for water leakage.
If containment entry is impractical during operation, perform a containment inspection for water leakage at the first plant shutdown for any reason subsequent to receipt of this bulletin.
f.
Establish procedures to notify the NRC of any service water system leaks within containment via a special licensee event report (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with written report in 14 days) as a degradation of a containment boundary.
RESPONSE
Item 2A.
The containment vessel drains to the lowest point in containment,,that being the normal sump.
Therefore, a significant accumulation of water in containment (including the reactor vessel pit) would be detected by a high level in the normal sump. There are four instruments located in the normal sump which detect an accumulation of water in the normal sump. These instruments promptly alert the contrcl room operators to a
Re:pon:
to IE Bull 3 tin 80-24 Dock:t No. 50-346 Sr. rial Sr. 1-179 significant accumulation of water in the containnent normal sump.
These instruments provide the control room operators with the follow-ing alarm information:
NORMAL SUMP INFORMATION DISPLAYED IN THE CONTROL ROOM COMPUTER POINT ALARM LEVEL INSTRUMENT ANNUNCIATOR CRT ALARM TYPER INDICATION LSH 1546A X
X Y
LSH 1546B X
X X
LT 1546A X
X X
LT 1546B X
X X
Therefore, there currently exists a redundant means for the detection and prompt alerting of control room operators to a significant accumulation of water in containment..The existing instrumentation therefore satisfies the requirements of this Item 2A.
RESPONSE
Item 2B.
The containment normal sump contains two sump pumps which remove the ac-cumulation of water in the' sump by pumping the water from containment to a drain tank, located in the Auxiliary Building.
The control room operators normally determine the flow from the normal sump by recording the elapsed pumping time of each sump pump motor.
Each sump pump motor has an elapsed time meter located in the Auxiliary Build-ing.
Using the elapsed pumping time from each pump and the known pumping capacity of each pump the flowrate from the normal sump is determined.
An additional methed can be used to determine the volume of a signifi-cant amount of water pumped from the sump. The discharge of the sump pumps normally flows into the Miscellaneous Waste Drain Tank (MWDT).
Observation of a level change in the Miscellaneous Waste Drain Tank could be utilized to calculate a significant flowrate f rom the normal sump.
RESPONSE
Item 2C.
The operability of the normal sump level instrumentation and sump pump is currently verified by the performance of ST 5041.01, " Containment Vessel Normal Sump Level and Flow Monitoring System Channel Calibration Surveillance Test" and ST 5041.02, " Normal Sump Level and Flow Monitoring System Channel Calibration Surveillance Test."
Both ST 5041.01 and ST 5041.02 are performed every 18 months per Technical Specification 4.4.6.1.b.
No existing Surveillance Tests currently verify the operability of normal i
sump level indicators and sump, pumps on a more frequent basis.
L
Rc;pon:9 to IE Bullatin 80-24 Dockst No. 50-346 S2 rial N2. 1-179 ST 5099.02, Daily Instrument Channel Check Surveillance Test will be modified to include:
- 1) Verification of the operability of the sump level instrumentation, via a channel check and sump pumps.
- 2) The recommendation to evaluate the limitation of power operation during the inoperability of the sump level indication system or sump pump system.
- 3) Added surveillance measures during the inoperability of the sump Icvel-indication system or sump pump system.
The modifications to ST 5099.02 are scheduled to be completed by February 15, 1981.
RESPONSE
Item 2D.
The containment normal sump flowrate is determined approximately once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (in Modes 1-4) by the performance of ST 5099.01, " Mis-cellaneous Instrument Shif t Check Surveillance Test'!.
Any increase it.
containment Icakage will be reflected by an increase in the normal sump flowrate.
ST 5099.01 is being modified to include guidelines for the determination of the source of a significant increase in containment leakage and if necessary the isolation of the suspected component. The modification to ST 5099.01 is scheduled to be completed by February 15, 1980.
A general inspection of coatainment is required to be performed by PP 1102.02, " Plant Startup Procedure" prior to reaching criticality on each plant startup.
RESPONSE
Item 2E.
Since containment entry is impracticai during operation, a containment inspection for water. leakage was performed following the first plant shutdown, at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> on December 6, 1980.
The containment vessel will be inspected for water leakage following future plant shutdowns until the implementation of measures described in items 2c & 2d.
(Scheduled to be completed by February 15, 1980).
RESPONSE
Item 2F.
ST 5099.01 " Miscellaneous Instrument Shift Check" uill be modified to provide a guideline to notify the NRC via a special licensee event report (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with a written report in 14 days) upon verification, of a significant service water leak in containment.
The modification to ST 5099.01 is scheduled to be completed by February 15, 1981.
R::pon:0 to IE Bull:tia 80-24 Dock;t No. 50-346 Serici N;. 14179 0
ITEM 3 For plants with closed cooling water systems inside containment provide a summary of experiences with cooling water system Icakage into contain-ment.
RESPONSE
The containment vessel contains one closed cooling water system, the Component Cooling Water System.
The Component Cooling Water System supplies cooling water to the following components in containment:
- 1) Reactor Coolant Pump - seal coolers
- 2) Reactor Coolant Pump Motor - air coolers, bearing coolers
- 3) Control Rod Drive Motor coolers
- 4) Reactor Coolant Letdown cooler An investigation was performed to identify experiences of Ccmponent Cooling Water System Icakage into containment.
A review of equipment files indicated that five minor repairs were required.
The minor leaks were as follows:
1)
CCW vent valve found leaking 2)
Instrument fitting leaking on RCP l-1-1 bearing oil cooler 3)
Flange leaking on RCP 1-1-2 seal cooler 4)
Flange leaking on RCP 1-1-1 bearing oil cooler 5)
Swagelock fitting leaking on a Control Rod Drive Motor The CCW header in containment was hydrostatically tested for leakage during the past refueling outage. Prior to the performance of the hydrostatic test, valves that are normally capped are uncapped. The piping system is then pressurized and the system is inspected for leaks.
Six valves were found to be Icaking, five with a leakage $75 drops / min and one vent valve with a larger leakrate.
All six valves were repaired.
The six valves which were fouad to be leaking during the test would be capped during normal operation and thus would not have produced Icakage into containment unless the caps had leaked.
t
e SUBMITTAL FOR THE DAVIS-BESSE NUCLEAR POWER STATION UNIT 1 FACILITY OPERATING LICENSE NPF-3 IN RESPONSE TO A CFR 50.54 (f)
REQUEST DATED NOVEMBER 21, 1980 j..
I This response is filed in accordance with 10 CFR 50.54(f) relating to Mr. James G.Keppler's letter of November 21, 1980.
This deals with the. prevention of damage due to water leakage inside containment.
By Vice' President, Nuclear l
Sworn to and' subscribed before me this fifth day of January, 1981.
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