ML19276F028
| ML19276F028 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/06/1979 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| TASK-05-10.A, TASK-5-10.A, TASK-RR NUDOCS 7903270014 | |
| Download: ML19276F028 (6) | |
Text
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[.,,, %%,t UNITED STATES
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NUCLEAR REGULATORY COMMISSION 3%
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- [Fr \\\\ j WASHINGTON, D. C. 20555
%; V /j March 6, 1979 Docket No. 50-155 Mr. David Bixel Nuclear Licensing Administrator Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201
Dear Mr. Bixel:
Enclosed is a copy of our draft evaluation of Systematic Evaluation Program Topic Y-10.A.
You are requested to examine the facts upon which the staff has based its evaluation and respond either by confirming that the facts are correct, or by identifying any errors.
If in error, please supply corrected information for the docket.
We encourage you to supply for the f.ccket any other material related to this topic that might affect the staff's evaluation.
Your response within 30 days of the date you receive this letter is requested.
If no response is received within that time, we will assume that you have no comments or corrections.
- ncerely, kb Dennis L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors
Enclosures:
Topic V-10.A cc w/ enclosures:
See next page
?soaz?cCM'
Mr. David Bixel March 6,1979 cc Mr. Paul A. Perry, Secretary Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Hunton & Williams George C. Freeman, Jr., Esquire P. O. Box 1535 Richmond, Virginia 23212 Peter W. Steketee, Esquire 505 Peoples Building Grand Rapids, Michigan 49503 Charlevoix Public Library 107 Cl-inton Street Charlevoix, Michigan 49720 K M C Inc.
ATTN:
Mr. Jack McEwen 1747 Pennsylvania Avenue, N. W.
Suite 1050 Washington, D. C.
20006 9
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SYSTEMATIC EVALUATION PROGRAM PLANT SYSTEMS / MATERIALS BIG ROCK POINT Topic V-10.A Residual Heat Removal System Heat Exchanger Tube Failures The safety objective of this review is to assure that impurities from the cooling water system are not iritroduced into the primary coolant in the event of shutdown cooling system heat exchanger tube failure. This was expanded to assure that adequate monitoring exists to assure no leakage of radioactive material in the other direction - into the service water and thus to the environment.
Infonnation for this assessment was gathered from plant personnel during the safe shutdown review site visit in June 1978 and from related telephone conversations.
Infonnation was also taken from the Big Rock Point Techni-cal Specifications and the Big Rock Point Final Hazards Sumary Report.
The bases for the review of these cooling systems on today's plants include: (1)'theNRC'sStandardReviewPlan (SRP) 9.2.1, which requires that the service water system include the capability for detection and control of radioactive leakage into and out of the system and prevention of accidental releases to the environment; (2) SRP 9.2.2, which requires that auxiliary cooling water systems (such as the shutdown cooling system) include provisions for detection, collection and control of system leakage and means to detect leakage of activity from one system to another and preclude its release to the environment; and (3) SRP 5.2.3, which I
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. discusses compatibility of materials with reactor coolant and requires monitoring and sampling of the primary coolant system. These Standard Review Plans were used only in the comparison of Big Rock Point against today's criteria and were not used as licensing requirements which must be met, especially if the plant incorporates other equally viable means of accomplishing the stated goals.
Because the Shutdown Cooling System (SCS) heat exchangers (2) are on the suction side of the shutdown cooling pumps, the primary (reactor coolant) side of the heat exchangers may be at a pressure as low as 11.5 psig.
The secondary side of these heat exchangers is the Reactor Cooling Water (RCW) system, which' operates at a maximum pressure of 66 psig.
- Thus, if there were tube failure (s) inleakage of RCW into the primary system would occur.
There has been no inservice code-approved hydrostatic test of the SCS heat exchanger tubes, although what serves as a quasi-hydrostatic test is performed during each SCS startup, according to plant sources.
This occurs because the systemis typically initiated when primary pressure is in the range of 150-280 psig, much greater than the normal pressure noted above. Additionally, a requirement will be levied as part of the staff's generic 10 CFR 50.55a (g) review.
Although the new inservice inspection program requirements were originally scheduled to begin with the 40-month interval commencing September 1,1978, the staff has approved a delay until February 1979 to more closely coincide with a planned refueling outage,
. As protection against undetected leakage into the primary system, the Big Rock Point RCW system water tank incorporates a low level alarm which will alert the plant operators to leakage through the SCS heat exchangers (or any of the other components cooled by the RCW system).
In addition, althoughofnoneedwithregardtotheSCSheatexchanger(unlessRCW is shut down), the RCW system incorporates a radiation detector and alarm, as does the service water system, which cools the RCW heat exchangers and is thus the ultimate heat sink.
The RCW system pressure at the two RCW heat exchangers is only a "few inches of water", according to a licensee (Consumers Power Company) source. Because the service water pressure at these heat exchangers varies between 19 and 25 psig, the possibility exists for inleakage of contaminants from Lake Michigan into the RCW system. As noted above, such inleakage could find its way into the primary coolan.t system during SCS operation because of the differential pressures across the SCS heat exchanger. Although this scenario presumes failures of tubing in a combination of the SCS and RCW heat exchangers, such a combination, with resultant primary system contamination, cannot be ruled out, given that no inservice inspection of heat exchanger tubes has been performed and that differential pressures would aid such leakage.
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4-Big Rock Point procedures require the twice weekly analysis of the RCW system, testing for chromates (a compound of which is used in the RCW system as a corrosion inhibitor), chloride, and conductivity. These tests will adequately detect any inleakage from the SW system, but added defense and early warning could be obtained by the incorporation of a high level alarm in the RCW system water tank.
Presently only the low level alarm exists as protection in addition to the twice weekly sampling.
The staff will examine this further during the integrated assessment at the end of Design Basis Event review.
As defense against primary system contamination during power operation, Big Rock Point Technical Specification 4.1.2(b) requires daily primary coolant sampling, which includes chlorides and conductivity. This should be expanded to include sampling during shutdown when the SCS is l
in operation and thus when leakage into the primary system is most likelye As noted above, the recommendations for improvements will be reviewed as part of the integrated assessment. No action on the part of the licensee is necessary at this time.
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