ML19346A334
| ML19346A334 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, Zion  |
| Issue date: | 05/26/1981 |
| From: | Rausch T COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-81-03, IEB-81-3, NUDOCS 8106190159 | |
| Download: ML19346A334 (7) | |
Text
t Commonwealth Ed' son o.,e First National Ptata. Chicago. tilinois y Address Reply to: Post Off+ce Box 767 CNesgo, Ilknois 60690 May 26, 1981 9,,/j /
7 m
Mr. James G. Keppler, Director
/3' p
l-JUli23Lc21 gl Directorate of Inspection ano
!d v,,,,,mu ne ym, %
Enforcement - Region III U.S. Nuclear Regulatory Commission
, p.
haw j
799 Roosevelt Roaa S
Glen Ellyn, IL 60137 g
Suoject:
Dresoen Station Units 1, 2, ano 3 Quad Cities Station Units 1 ara 2 Zicn Station Units 1 and 2 Response to IE Bulletin 81-03 Concerning Flow Blockage Due to Cerefcula ana Mytilus NRC Docket Nos. 50-10/237/249, 50-254/265, and 50-095/304 Reference (a):
J. G. Keppler letter to C. Reec catec April 10, 1981
Dear Mr. Keppler:
Commonwealth Eaison has reviewed the Reference (a) transmittal of IE Bulletin 81-03 as it applies to our operating nuclear units.
The enciosure to tnis letter contains the requestea 45 day report for Dresoen ana Quad Cities stations.
A clam survey was conaucted on April 28, 1981 at Zion Station.
The results of this survey along with a review of 10 years of macroinvertebrate samples collectea from Lake Michigan substrates indicates that Corbicula were never founa in t.he Zion Station source i
or receiving water booies.
The remaining portions of the bulletin regaraing methods for cetecting anc preventing future ficu blockage are still unoer review for Zion Station.
We expect f.f.
submit our response ny June 5, 1981.
It *houla be noted that for all Commonwealth Eaison stations, infestations of Mytilus is not a concern since we do not use salt water cooling systems.
To the best of my knowledge and belief the statements contained hereing anc in the enclosure are true anc correct.
In e i
some respects these statements arat not based on my personal h(
knowledge but upon information furnished by other Commonwealth Edison employees.
Such information has been reviewec in accorcance with Company practice and i believe it to be reliable.
00 gy g 8 $81
2-Please address any questions you may have concerning this matter to this office.
Very truly yours, W
Thomas J. Rausch Nuclear Licensing Administrator Special Projects Enclosure cc:
Director, Office of Inspection ano Enforcement, Wash., DC NRC Resident Inspector - Dresoen NRC Restoent inspector - Quac Ctties NRC Resioept -Inspector - Zion SUBSCRIBED and S'4CR N. t o before me this dM oay ot // A.' <
196.
iln Th $.:" <.- { i, u.
i Hvfary Public s-J 2060N 4
a 1
1
--,n-.-+nn
.n..-
-.,,, ~
...,.e
5.
o i
Enclosure Commonwealth Eoison Company Oresden Station Units 1, 2 and 3 Quaa Cities Station Units 1 ana 2 Response to IE Bulletin 81-03 Dresaen Units 1, 2,
and 3:
The presence of Asiatic Clams in the source waters of Dresoen Station has been known for some time.
a positive aetermination of their existence was made by the Environmental Affairs Department on March 25, 1981 during a barrier net survey at Drescen. Station.
They observed Asiatic Clams (Corbicula Species) in the Unit 2/3 cribhouse between the car rack anc the traveling screens.
Live specimens of all size ranges as well as many deaa specimens were discovered.
These findings indicate that the populations are actively reproducing and, in fact, do present the potential fouling anc plugging problems occurring at other generating stations.
All systems receiving Circulating Water anc Service Water are affecteo by the presence of Asiatic Clams (see attacnment for a list of affecteo components).
These weter systems are supplied by two sources:
Dresden Lake and the Kankakee River.
Althougn the water quality of-Drescen Lake is much better than that of the Kankakee, both contribute mud, silt, sand, ana bacteria to the intake structures.
Our experience has shown that this assortea aebris is the primary mechanism for the plugging and fouling of heat exchangers and related piping with the clam population being a seconcary factor.
At present, no accumented program exists for monitoring the clam oopulation in the plant.
The primary mechanism for preventing clam infestation is the hypochlorite injection system.
Hypochlorite is injected, in the necessary ccncentrations, into each section of the condenser at staggerec intervals.
This chemical treatment is effective in treating slime and bacterial growtn on concenser tvDe walls as well as killing clam-larvae.
Hypochlorite is also used in the Service Water System as a clam and bacteria inhibitor.
Larger heat exchangers, where lower flows are encounterea, generally collect more clams between clear.ings than heat exchangers with flows of greater velocity.
This phenomenon is recognized and accountea for by the' frequencies with which various heat exchangers I
are cleanea.
~
All safety related system heat exchangers, incluaing the condenser, are equipped with differential pressure (DP) indicators.
The operating engineers monitor these sjstems on a day-to-day basis
-and schecule routine visual examination and manual cleanings as needed.
The safety related system heat _exchangers are cleaned at least once per-refueling outage and more often if differential pressure indications show degradation.
All non-safety *elatea heat exchangers receiving cribhouse water are manually cleaned at any sign of reouced system performance.
The fire protection system at Dresden uses service water which is treated with hypochlorite.
This systen contains larger ciameter pipts and no heat exchangers thus reducing the probability of flow blockage.
The Dresden fire protection proceaures incluce inspection, flushing and operability on an annual basis.
Our experience has shown these procedures to be completely adequate to prevent system degradation.
A Service Water Heat Exchanger program is now being developed, and the progress of this program will be monitorea by AIR 81-37.
Initiation of this program requires differential pressure (DP) indicators to be installed on all heat exchangers receiving Service hater.
Heat exchanger cleaning will then be based on this cata whicn will be taken quarterly.
The enclosea attachment indicates which heat exchangers ha*.e DP indication and/or hypochlorite adaition.
We believe the present method of dealing witn the clam problem has been satisfactory but furthe-improvements can be maae.
The above mentionea program will provide some of these improvements.
In the future, continuing efforts will be maae to disccver more effective clam control methods and possibly a permanent solution.
t
ATIACEMENT Components affected by clam infestation: Heat Exchangers Systems receiving Unit 2 & 3 Service Water:
Existing Receiving Unit Pressure Hypochlorite Number Indicator Injection System Affected 2/3 No Yes Offgas Glycol Chillers 2/3 No Yes Offgas Filter Building Air Particulate Vacuum Pumps 2/3 No Yes Concentrator Condenser 2/3 Yes Yes Control Room Air Conditioning 2/3 No Yes Auxiliary Electric Room Air Conditioning 2&3 Yes Yes Turbine Oil Coolers 2&3 Yes Yes Turbine Building Closed Cooling Water 2&3 Yes Yes Reactor Building Closed Cooling Water 2&3 Yes Yes Main Generator Hydrogen Coolers 2&3 Yes Yes Main Generator Scator Coolers 2&3 Yes Yes MG Set Oil Coolers 2&3 No Yes X-Area Coolers 2&3 Yee No Containment Cooling Service Water 2&3 Yes No Standby Diesel Generator 2&3 No No Emergency Air Coolers (1 HPCI, 2 Reactor Bldg.)
Systems Receiving Unit 2 & 3 Circulating Water:
2&3 Yes Yes Main Condenser Systems Receiving Unit 1 Service Water:
1 Yes Yes Reactor Enclosure Cooling 1
Yes Yes Turbine Building Cda?ing Water 1
Yes Yes Fuel Handling Bui10.ng 1
Yes Yes Hydrogen Coolers 1
Yes Yes Turbine Lube Oil Coolers 1
Yes Yes Wasta Vapor Condenser 1
No Yes Control Room Air Conditioner 1
No Yes Administration Building Air Conditioner 1
No Yes Access Control Building Air Conditioning 1
No Yes Reactor Enclosure Air Conditioning Unit 1
No
, Yes Isolated Phase Bus Air Coolers Syst us Receiving Unit 1 Circulating Water:
1 Yes ies Main Condenser The Environmental Monitoring Program's last sample data and results show no residual chlorine at the time.of the sampling (5/15/81).
E
~
~
.e
.m
..,w-~~
e
,p4
-m---
1 QUAD CITIES UNITS 1 ina 2 As required by Item 1 page 3 of IE Bulletin 81-03, Commonwealth Edison Environmental Affairs Department conductea a survey of the Quad Cities Intake structure and cribhouse a'ea.
Live specimens of Corbicula were found in all size ranges, as well as many dead specimens during a special survey conducted on April 29, 1981.
This inoicates that populations are reproducing in the vicinity of the Station.
As a result, inspections outlinea in the Bulletin were performed.
The fire protection system, and the following safety related equipment are covereo by the Bulletin:
RHR Heat Exchangers, RHR Service Water Pumps. RHR Service Water Pump Cubicle Coolers, RHR Pump Seal Coolers, RHR Pump Motor Coolers, Diesel Generator Cooling Water Pumps, Diesel Generator Heat Exchangers. ECC System Room Coolers anc Diesel Generator Cooling Water Pump Cubicle Coolers.
Inspections ana flow tests hava been performed on some of this equipment during the last nine months.
The Unit One Diesel Generator Heat Exchanger was replacec on October 9, 1981.,because of tube leaks.
No excessive f low blockage was observed at this time.
Annual flushing of internal fire system piping was peformed in accordance with proceaure QMS 100-7 on November 20, 1980.
Flushing of external fire system piping was performed in accordance with procedure QMS 100-8 on October 25, 1980.
These. tests confirmed adequate flow at hose stations distributed over the Station.
No inaications of flow blockage were observea.
In accition to this, the Diesel ariven Fire Pumps were tested for capacity in accordance with procedure QOS 4100-7 on October 25, 1980.
The results of this test were satisfactory and showed no indication of flow blockage.
The RHR Service Water System is testea monthly.
The results of the most recent tests were acequate with no indication of flow blockage of the RHR Service Water Pumps or RHR Heat Exchangers.
Special Test 1-52 was performea on May 19, 1981, to determine the flow through the Diesel Generator Heat Exchangers and all the ECCS System room coolers for both units.
The results of this test showed no major sigr'ficant flow restrictions in this equipment.
However, the Unit Two RHR Room Coolers were shown to have less than desirable flow rates.
For this reason, an RHR Room Cooler will be inspected auring the upcoming Unit Two Refueling Outage.
In addition to the above safety related equipment, additional, non-safety related equipment has oeen inspected during the last nine months.
This equipment includes the following Unit One components:
Turbine Building Closed Cooling Water Heat Exchangers, Recirculation MG Set Oil Coolers, Turbine Oil Coolers, and Hydrogen Coolers.
All these heat exchangers showed no excessive 1
flow blockage due to Corticula, although some small shells and debris were found in so;ae of these heat exchangers.
The Service Building air conditioning unit HCN's were overhauled in February of 1981.
These heat exchangers were found to be blocked witn an accumulation of Corbicula shells.
This is the only instance of major flow blockage caused by Corbicula which has been found at Quad-Cities Station.
- r*-
2 The Station plans to perform aoaitional equipment Inspections during the upcoming Unit Two Refueling Outage in the fall of 1981.
This equipment incluces one Instrument Air Compretsor Heat Exchanger, one MSIV Room Cooler, one RHR Pump Seal Cooler, one RHR Pump Motor Cooler, one RHR Service Water PumD Cubicle Cooler ano one RHR Room. Cooler.
It is felt that this will give a representative sample af safe.y related systems using water ' rom the intake structure.
Present testing is sufficient to detect excessive flow blockage.
The flow througn the RHR Service Water Pumps ano RHR Heat Excnangers is tested on a monthly basis.
The flow rate of tne Diesel Generator Cooling Water Pumps and the total flow to the ECC System Room Coolers is taken on a quarterly casis.
The capacity test of tne Diesel ariven Fire Pumps is cone every operating cycle, and the fire system piping is flushed once every year.
In aaaition to this, various heat exchangers cooled by service water are overhaulea on a regular bcsis during refueling outages.
It is felt thct these measures should be sufficient to aetect flow degracations before they become significant.
Quac Cities Station is planning t begin injection of a biociae into the Serv ice Water System.
This should help to control Corbicula in the larval stage in this system.
No biocice has Deen injectea in this system for over two year;.
Acaitional methoas to control Coroicu la are still under investigation at the Station.
Circulation of hoc water through systems has provea effective at other stations, but we have no metboa for doing this without plant maaifications to safety related equipment.
Since the Station has not encounterea significant flow blockage in safety relateo equipment, this is not consiaered necessary at this time.
1
-r
-