ML20197D604
| ML20197D604 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, Zion, 05000000 |
| Issue date: | 05/31/1988 |
| From: | Morgan W COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 0346N, 346N, GL-88-05, GL-88-5, NUDOCS 8806070339 | |
| Download: ML20197D604 (5) | |
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Commonwealth Edison
, One First National Plaza. Chicago, lltinois Address Reply to: Post Offee Box 767 Chicago, Illinois 60690 0767
_p May 31, 1988 Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Zion Station Units 1 and 2 Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Response To NRC Generic Letter 88-05 NRC Docket Nos. 50-295/304, 50-454/455 And 50-456/457
Reference:
NRC Generic Letter 88-05, Dated March 17, 1988
Dear Mr. Davis,
The above referenced Generic Letter requested information to assess safe operation of pressurized water reactors when reactor coolant leaks below Technical Specification limits develop and the coolant containing Boric Acid comes in contact with and degrades low alloy carbon steel components.
Commonwealth Edison has complete its review pursuant to the request outlined in NRC Generic Letter 88-05 for Zion, Byron and Braidwood Nuclear Power Stations.
Th.'.s information is attached in Enclosure 1.
To the best of my knowledge and belief, the statements contained above are true and correct.
In some respect these statements are not based on personal knowledge, but obtained information furnished by other Commonwealth Edison employees, contactor employees, and consultants.
Such information has been reviewed in accordance with company practice, and I believe it to be reliable, i
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Please address any questions that you or your staff m4., have concerning this response to this office.
Respectfully, WyMorgantWy W.E.
Nuclear Licensing Administrator rf/4710K Attachments cc: Resident Inspectors - Z/By/BW Document Control Desk r
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' Zion, Byron ar.d Braidwood Respon3e to Generic Letter 88-05 Boric Acid Corrosion of' Carbon Steel Reactor Pressure Boundary Components in PWR Plants Huclear Regulatory Commission (RRC) Generic Letter 88-05 requests information to access safe operation of pressurized water reactors (pWHs) when
' reactor coolant leaks below Technical Specification limits develop and the coolant containing boric acid com6s in contact with and degrades low' alloy carbon' steel components. The NRC concerns regarding this issue were prompted by incidents in PWR plants,where leaking reactor coolant caused significant corrosion problems. Generic Letter 88-05 requests information regarding the programs that have itsa implemented to ensure that boric acid corrosion does not degrade the reactor coolant pressure boundery.
Commonwealth Edison's response is as follows, the numbered concern items correspond to the numbered concern items in the NRC Generic Letter 88-05.
Response to Concern 1:
At Byron and Braidwood Stations, most of the reactor coolant pressure boundary is composed of stainless steel.
Carbon Steel components on the reactor coolant pressure boundary include the reactor pressure vessel, pressurizer, steam generators, and reactor coolant pump flange bolting.
The principal locations where leaks that are cmaller than the allowable Technical Specification limits can cause degradation of the primary pressure boundary by boric acid attack are the steam generator primary side manway bolting, reactor pressure vessel head closure bolting, pressurizer manway bolting, and the i
reactor coolant pump flange bolting.
At Zion Station, reactor coolant pressure boundary components composed of carbon steel include the reactor pressure vessel, pressurizer, steam generators, reactor coolant pump flange 3
bolts, and a large number of fasteners used for mechanical closures that include valve flanges, packing glands, pipe flanges, etc. The principal locations where leaks that are smaller than the allowable Technical Specification limits can cause degradation of the reactor coolant pressure boundary by boric acid attack are the Steam Generator primary side manway bolting, reactor pressure vessel head closure bolting, pressurizer manway bolting, and the reactor coolant pump flange bolting. Valve packing glands, i
gaskets in bolted flange connections, and reactor head canopy. seal welds, are locations which have the potential for conditions that could cause high concentrations of boric acid on carbon steel pressure boundary components.
l Response to Concern 2:
l For locating small coolant leaks, Commonwealth Edison's PWR's utilize the Commonwealth Edison Company Special Process Procedures Manual VT-2 Procedure.
l This procedure is utilized to perform ASME Section XI required VT-2 visual I
examination of pressure retaining components during the conduct of system pressure or functional tests.
This Procedure utilizes hSME Section XI VT-2 certified visual examiners and meets the requirements of ASME Section XI VT-2 visual examination.
The visual examinations are performed to locate evidence of leakage from pressure retaining components or abnormal leakage f r om components with or without leakage collection systems.
This VT-2 procedure specifically requires that accumulation of boric acid residue on or near the l
l borated system be investigated to determine the source of Icakage.
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' Response to concern 3:
m The examination is conducted in accordence with the Commonwealth Edison Company Special process procedures Manual VT-2 procedure. This procedure meets the requirements of ASME Section X1 VT-2 visual examination. The inspection addresses all reactor coolant pressure boundary components, which are examined for evidence of leakege. The procedure specifically addresses boric acid accumulation or evidence of boric acid accumulation. At Zion station, this VT-2 examination is performed prior to and after each refueling outage. performing the VT-2 examination prior to a refueling outage assures that certified VT-2 examiners perform their examination before boric acid accumulations are removed during refueling outage activities.
The current VT-2 program used at Zion station has be-an successful in locating evidence of
-boric acid leakage station and remedying the situation. At Byron and Braidwood Stati~on,. provisions are being made to ensure that the VT-2 examination is performed both prior to and after the refueling outage, in a manner similar to Zion.
Commonwealth Edison _has closely reviewed the VT-2 procedure and has concluded that the procedure does not always ensure proper evaluation of all boric acid leakage conditions. As a result, Commonwealth Edison will revise the appropriate procedures to ensure that whenever boric acid leakage is identified during the VT-2 examinstions, the condition is reported on the VT-2 form. Tne procedure revision will ensure that all boric acid leakage identified during the VT-2 examinations are subject to the review of the Station Lead Level II VT-2 examiner.
In this manner, the VT-2 form will serve as a record of all boric acid leakage reported during the VT-2 examination.
The necessary procedure revisions are expected to be completed by September 1.
1988. The current VT-2 procedure ensures that when degradation of the pressure boundary has occurred due to borated water or boric acid leakage, a
. Deviation Report is written.
The Deviation Report requires further evaluation beyond the Lead Level II VT-2 examiner.
Response to concern 4:
Actions to prevent recurrence of boric acid corrosion include the use of Deviation Reports as directed in the VT-2 procedure for cases when aegradation of the pressure boundary has occurred.
The Deviation Report includes corrective actions, and actions to prevent The Deviation Report may be subject to Engineering evaluations recurrences.
as applicable, i
Summary The plan described above represents Commonwealth Edison's approach toward addressing the concerns of Generic Letter 88-05.
The current VT-2 program used at Zion Station has been successful in locationg evidence of boric acid l
leakage and remedying the situation.
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' This response to the items identified in Generic Letter 88-05 indicates
- actions which commonwealth Edison will take to improve its visual examination program to detect boric. acid leakage.- Such actions include the VT-2 examination before the ' refueling-outage at Byron and Braidwood to account for the experience gained atfat~-Zion.
Also,-the visual examination procedures-
-used at Commonwealth Edison for VT-2 examination will.be revised to better ensure.that'when boric acid leakage is discovered, it is properly evaluated.
The foreg'ing revision is expected-to'be completed by September 1, 1988.
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