ML20002D250
| ML20002D250 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, Zion  |
| Issue date: | 01/05/1981 |
| From: | Rausch T COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-24, NUDOCS 8101200155 | |
| Download: ML20002D250 (6) | |
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'n January 5, 1981 Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Dresden Station Units 1, 2, and 3 Quad Cities Station Units 1 and 2 Zion Station Units 1 and 2 Response to IE Bulletin 80-24
" Prevention of Damage Due to Water Leakage Inside Containment" NRC Docket Nos. 50-10-237/249, 50-254/265, 50-295/304 Reference (a ):
J. G. Keppler letter to C. Reed dated November 21, 1980.
Dear Mr. Keppler:
Reference (a) transmitted IE Bulletin 80-24 requesting a response to concerns identified as a result of the October 17, 1980 Indian Point 2 event.
Enclosed is Commonwealth Edison Company's response for Dresden, Quad Cities, and Zion Stations.
Please note that no response is provided for Dresden Unit 1, which is currently undergoing an extensive modification and chemical cleaning outage.
The bulletin will be addressed prior to the startup of the unit, now scheduled for June, 1986.
Approximately 100 manhours were expended in conduct of the review and preparation of this report.
A minimum of 200 ad-ditional manhours were required to complete the corrective actions (procedure modifications, interim surveillances, etc.) required by the bulletin.
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Please address any questions you may have concerning this matter to this office.
Very truly yours,
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Thomas J. Rausch Nuclear Licensing Administrator Special Projects cc:
Director, NRC Office of Inspection & Enforcement Washington, DC 20555 RIII Inspector - Dresden RIII Inspector - Quad Cities RIII Inspector - Zion SUBSCRIBED and SWORN to befor me this 6 -r N,da y
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r ENCLOSbRE Commonwealth Edison Company Response to IE Bulletin 80-24 Dresden Units 2 and 3, Quad Cities Units 1 and 2 Dresden Units 2 and 3 and Quad Cities Units 1 and 2 utilize a closed cooling water system (Reactor Building Closed Cooling Water System or RBCCW) to provide cooling to drywell components.
These components include the Recirculation Pumps and Motors,_Drywell Coolers, and the Drywell Equipment Drain Sump Heat Exchanger.
The RBCCW system is an interface system with no direct path between the drywell and the environment, and is, as defined by GDC-57, a closed system.
Cooling water system leakage has not been a problem for these units.
It should also be considered thtc u.e to the construction of the drywell and torus, it is not possible to accumulate any large quantiti of water under the reactor vessel.
These stations mm constructed such that during a LOCA or similar event, the area under the vessel will drain via the downcomers into the torus.
This would also occur during an event such as described in the bulletin.
With no pumpage, the sumps would overflow to the dry-well floor, and once the level reached downcomers, it would flow into the torus.
Since the torus level is monitored, this in-crease would be noted and investigated.
Even under this scenario, the water would not reach a level where it could adversely affect any critical system.
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ENCLOSURE O
Commonwealth Edison Company Response to IE Bulletin 80-24 Zion Station Units 1 and 2 ITEM 1 A/B.
Zion Station has one open cooling water system inside containment.
This consists of essential service water supplied to the reactor containment fan coolers.
The re are five fan coolers in the Zion Station Containment.
The design basis accident heat loads require three fan coolers for adequate heat removal.
Normal operations re-quire a maximum of four fan coolers.
The service water used in the fan coolers is strained water from Lake Michigan.
If a fan cooler is not being used, the service water to it is not normally isolated.
C.
The headers to the fan coolers are made of carbon steel 2e the coolers themselves are plate finned copper-nickel 90-1D with a galvanized steel frame.
D/E.
Zion Station has never experienced fan cooler tube leaks.
However, after the 1980 Unit 2 refueling outage one gasket leak was identified on the water supply header and blanked off effectively stopping the leak.
This leak occurred after the reassembly of the heat exchanger's after tube cleaning.
Permanent repairs are scheduled for the 1981 refueling outage.
This is the only known leakage problem to have occurred on the Zion Station Reactor Containment Fan Coolers.
There have been no major repairs to the cooling system piping.
F.
In the event that a fan cooler must be isolated, there are manual Isolation valves at the inlet and outlet of each cooler.
These valves are located in containment.
There are also motor operated valves for system isolation.
All of the motor operated valves are located outside of the containment.
There is one motor operated discharge valve from each fan cooler and the valve is controlled from the control room.
The inlet motor operated valves are arranged on a common inlet header in such a way that two or three i
fan coolers can be isolated at a time.
These valves are locally operated in the Auxiliary Building.
Provisions exist for isolating all portions of the service water system inside containment in the event of the failure of any single isolation valve.
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For performing leek tests of isolation valves, Appendix J of 10CFR50 has no provisions for testing open cooling water isolation valves.
There are local gages for flow, pressure, and temperature on each of the discharge lines in the Auxiliary Building.
The pressure in these lines are kept above 47 psig to prevent leakage from the con-tainment during a design basis accident.
A radiation level recorder is on the common service water discharge header and annunciates in the control room on high level.
ITEM 2 A.
Unit 2 has independent dual indication on the safeguards panel in the control room of recirculation sump, con-tainment sump, and containment water levels.
Unit 1 has dual indication on the safeguards panel in the control room of recirculation sump level.
Installation of in-dependent dual indication containment sump and containment water levels will be accomplished during the next Unit 1 refueling outage to begin in January, 1981.
Both Units 1 and 2 have single alarm indication at the radwaste panel of high reactor cavity sump level.
With the com-pletion of these modifications, both units will have re-dundant means of detecting and promptly alerting control room operators of a significant accumulation of water in containment.
B.
Unit 1 and 2 containment sump pumps are equipped with pump run time meters.
Readings are obtained by the shift once per day.
C.
Surveillance procedures of at least monthly repetition will be instituted by June 1, 1981 to assure plant oper-ators have at least two methods of determining water levels in each location where water may accumulate.
The procedures shall require continued power operation be reviewed by_ station management after seven days where the detection system becomes inoperable or where no re-moval system is operable for a given water collection point.
The containment recirculation sump is to be ex-cluded from the removal system requirements.
We will not put equipment in the sump that could block RHR pump suction during the recirculation phase of an accident.
Water accumulation in the recirculation sump will eventually spill onto the containment floor and be pumped out of the containment sump.
D.
Containment entries are routinely made by the Operating Department with findings indicated on the Equipment Attendant Log.
During these inspections particular at-tention is given to any signs of leakage or water accumulation.
o E.
Interim surveillance measures were instituted, within 10 days of the bulletin date as required, which in-cluded periodic containment inspections during operation and inspections following containment closing subsequent to maintenance outages.
F.
A technical specification change will be submitted to establish procedures for reporting of service water leaks inside containment via a special LER report of a degradation of the containment boundary.
ITEM 3 Zion Station has a closed cooling system inside containment called the Component Cooling System.
There has been only one leak into containment from the component cooling system.
This leakage was discovered on June 30, 1980 in the Unit 1 containment.
The leakage was identified in these in-dependent ways.
First the decrease in component cooling inventory was noted by a decrease of level in the com-ponent cooling surge tank.
This low level alarm annun-ciates in the control room.
Secondly, the increase in containment sump pump run time indicated a leak inside containment.
Thirdly, a routine containment entry in-spection discovered component cooling water on the con-tainment floor outside the missile barrier.
Power re-duction was necessary to be able to inspect inside the missile barrier.
This was done, the leaking component discovered, and repairs made.
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