IR 05000409/1984009
| ML20154M808 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 03/10/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20154M800 | List: |
| References | |
| NUDOCS 8603140491 | |
| Download: ML20154M808 (2) | |
Text
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SAFETY EVALUATION BY THE
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0FFICE OF NUCLEAR REACTOR REGULATION LACROSSE BOILING WATER REACTOR (LACBWR)
DOCKET NO. 50-409 t
SHUTDOWN CONDENSER SAMPLE LINE
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Introduction
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i As a result of the SEP review of containment isolation systems at LACBWR, i
several corrective actions concerning administrative controls, procedures l
and locking devices for valves were identified (NUREG-0827 Section 4.21).
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During the region's verification of the licensee's actions, the staff identified an additional containment isolation issue, which is discussed in
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Inspection Report 50-409/84-09 dated October 5, 1984. The licensee
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proposed corrective actions in a letter dated February 8, 1985.
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Discussion I
The shutdown condenser, located inside containment, provides a heat sink
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when the reactor is isolated from the main condenser. Steam from the
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i main steam line passes through the tube side of the shutdown condenser where it is condensed by evaporating water on the shell side. The steam generated in the shell is exhausted to atmosphere, through a non-isolable t
vent line. A sampling line (1/2") is connected to the shell side to allow the water to be sampled. Two manual valves are provided on this Ifne, which are locked closed (with independent verification) except when a
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sample is in progress. The sample is taken inside containment and the
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manual valves can only be cot. trolled locally. The shutdown condenser
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is sampled twice per month and after use to ensure maintenance of high i
purity water such that the tube heat transfer characteristics are not
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degraded.
Should an event occur that releases steam to the containment while a sample is in progress, the individual perfoming the sampling may be unable to reclose the manual valves before leaving the containment.
If the containment
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pressure exceeds the head of water in the sample line, a direct path from the
containment atmosphere to the shell side of the shutdown condenser and thus
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to the environment would exist.
Evaluation
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In response to the staff's concern, Dairyland Power Cooperative (DPC)
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proposed to install two check valves in series in the sample line. This'
l arranqement would permit samples to be drawn, by opening of the two (existing)
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manua'
valves, but the check valves would prevent backflow of air through i
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the line even if the manual valves are not closed.
1, 1 As noted above, the two manual valves would normally provide the isolation function. The check valves will enhance the capability to isolate the
containment from the environment by providing additional barriers. The i
l modifications proposed by the licensee will provide an isolation boundary
between the containment atmosphere and the environment should an accident
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occur during the limited time periods while sampling is in progrc..s.
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Conclusion The staff concludes that the proposed modifications, in conjunction with the existing valving and administrative controls, provide acceptable isolation for the shutdown condenser sample line.
Principal Contributors: E. McKenna.
Dated: March 10, 1986.
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