ML19289C875
| ML19289C875 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 01/11/1979 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| References | |
| TASK-05-10.A, TASK-5-10.A, TASK-RR NUDOCS 7901250351 | |
| Download: ML19289C875 (6) | |
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't UNITED STATES
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1 NUCLEAR REGULATORY COMMisslON j
WASHINGTON, D. C. 20555 f
t Luut/j January 11, 1979 g,
Docket flo. 50-409 THIS DOCUMENT CONTAINS Mr. Frank Linder i
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General Manager Dairyland Power Cooperative 2615 East Avenue, South La Crosse, Wisconsin 54601
Dear f1r. Linder:
Enclosed is our draft evaluation of Systematic Evaluation Program topic V-10. A (Residual Heat Removal System Heat Exchanger Tube Failures).
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 error.
If in error, please supply corrected information for the docket. We encourage you to supply for the docket any other material related to this topic that might affect the staff's evaluation.
It would be most helpful if your comments were received within 30 days of the date you receive this letter.
Si ncerely, j
jUi.nw_ ja
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Dennis L. Ziemann',)hief Operating Reactort Branch #2
. Division of Operating Reactors
Enclosures:
Topics V-10.A cc w/ enclosures:
See next page 7901250361
ncer January li, 1979 i
cc Fric: 5.c cubert, E sc.' re Staf' Accerney Cairylard Det.er Coc;erative 2615 East Avenue Scuth La Crosse, Wisconsin 54601 C. 5. Meistand, Jr., Escuire
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1800 M Screet, N.
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Washin; ten, D. C.
20036 Mr. O. E. Shimshak La Orc se Boil'ng. ater Reactor C a ' r. '. a r : Dover Cecreraciv;
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Genc2,. scensin 5:632 egion Energy Coalition Coulee r ATT' Secrge R. Nygaard P. O. Ecx 1583 La Crossa, Wisconsin 54601 La Crosse Dublic Library 800 "ain Street La Crosse, Wiscensin 54601 K M C Inc.
ATTN:
Mr. Jack McEwen 1747 Pennsylvania Avenue, N. W.
Suite 1050 Washington, D. C.
20006
SYSTEMATIC EVALUATION FROGRAM PLANT SYSTEMS / MATERIALS
.LA CROSSE 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 introduced into the primary coolant in the event of decay heat remo' val system heat exchanger tube failure.
This was excanded to assure that adequate monitoring exists to assure no leakage of radioactive material in the other direction - into the low pressure service water and thus to the environment.
Information for this assessment was gathered from plant personnel during the safe shutdown review site visit and from related telephone conversa-tions.
Information was also taken from La Crosse system drawines and the La Crosse Technical Specifications.
The cases for the review of these cooling systems on today's plants include:
(1) the NRC's Standard Review Plan (SRP) 9.2.1, which requires hat'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 decay heat removal system) include provisions for detection, collection and control of system leakage and n.eans to detect leakage of activity from one system to ar.other and preclude its release to the environment; and (3) SRP 5.2.3, which
2 ciscusses compatibility of materials with reactor coolant ar.d recaires
- -i t:rin; ar.d sar. cling.of the prima ry coolant systen.
These Standard Revisa Plans were used only in the comparison of the La Crosse plant against today's criteria and were not dsed as licensing requirements mich must be met, especially if the plant incorporates other equally viable means of accomplicshing the stated goals.
The decay heat removal (DHR) system heat exchanger primary side is con-tinuously cressurized during normal reactor coeration, according to ir#or a-ion eresented on page 5-13 of the La Crosse Safeauards Recort, which states that the outlet valve is locked closed when the system is not in use. Therefore, during norr.al operation, there is no chance for cor.tamina:icn of the reactor coolant by leakace from the coroonent coolinc viater (CCW) System, which flows throuch the secondarv side of tne DHR neat exchancer.
However, at the lowest crimary oressure (reactor shut down and deoressurized, DHR not in operation, CCW in crerati:n'. the :tential exists for leakage of CCW into the crimary system if a tube or tubes in the OHR heat exchanger were broken.
Even with DHR in operation, the differential pressure across the DHR heat exchanger is such that a slight driving head could be available to force water through a leaking tube from CCW into the primary system.
La Crosse is protected from undetected leakage of' primary coolant into the FCW system because of the inclusion of a radiation detector and alarm-on the CCW system. Additionally, although a simultaneous failure of tubes
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in the DHR heat exchanger and CCW heat exchanger /_ cooled by the Low Pressure Service Water (LPSW) system _/ is highly unlikely, the plant is
protected against leakace to the enviror. ment by a radiation monitor, with alarm, in the discharge of the circulating water system (which ir.cludes the discharge of the LPSW syste:t).
' PSW system pressure is higher than that of the CCW system, and thus a potential leakage path (assuning failed tubing) exists from LPSW to CCW through the CCW heat exchangers.
It would take a highly unlikely second tubing failure in the DHR heat exchanger to allow LPSW contaminants (from the Mississippi River) into the pr imary system.
This would also require the specific conditions cited above for the primary system in its lowest rar.ge of c;eratinc pressures.
Were leakage to occur between CCW and the primary system, the plant operators would be warned of such, leakage by the CCW system surge tank low l evel alarm.
However, were simultaneous leakage to occur from both the CCW and DHR heat exchangers, it is questionable (depending on the ragnitude of each leakage) that this a'larm would sound.
Thus, the plant would be dependent upon primary system sampling of conductivity and chloride.
Although the present La Crosse Technical Specifications include a Limiting C.ondition for Operation (4.2.2.2., Page '30) for conductivity and chloride, there is no associated surveillance requirement. The NRC staff is currently working closely with the licensee in the development and usuance of Standard Technical Spe,cifications (STS), which will include the surveillance require-me n ts.
The STS are scheduled for issuance prior to completion of the Svstematic Evaluation orecran'and will resolve this topic.
In the interim, the lack of such requirements is acceptable since piant crocedures rec.uire samolinc.
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We have :cn:lu:sd that the potential of radioactive leakage to the environ-T.ent is mininized by the inclusion of the radiation monitors in the CCh' system and the circulating water system discharge.
The likelihood cf centaminant leakage into the primary system from either (or both) the OEP or CCW heat exchangers is small, given the relatively small amount of time that primary pressure is low enough that inleakage could occur.
However, since the only existing means of indication and alarm is the CC'l surge tank low level alarm, we believe that the surveillance r
re: Lire ents of the STS are necessary to assure adequate indication if inlea<3;e shoul: occur.
Because these requirements will be instituted pricr te cor?letion of the Systematic Evaluation Program (and because interim sampling is covered by plant procedures) we have determined that La Cr sse meets the intent of current licensing criteria and that no additional revie,: cf this topic is necessary beyond STS implementation.
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