ML20235U393
| ML20235U393 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 09/21/1987 |
| From: | Cornwell K, Klapproth J, Sozzi G GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20235U383 | List: |
| References | |
| CNSS876103, NUDOCS 8710140070 | |
| Download: ML20235U393 (3) | |
Text
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GE,408 925-4091 TEL No.
408 925 4091 Sep 21.87 12:30 P.02 CNSS876103 Page 1 of 1*
GENER AL (') ELECTRIC Enclosura 1 COOPER NUCLEAR STATION TURBINE BYPASS VALVE OUT-OF-SERVICE ASSESSMENT September 21, 1987 Cooper Nuclear Station (CNS) is currently operating at approximately 75% of rated thermal power with a critical power ratio (CPR) of approximately 1.50.
Early this morning a hydraulic fluid leak associated with one of the three turbine bypass valves was discovered.
The origin of the leak (high or low pressure hydraulic supply) is currently unknown.
In order to determine both the source of the leak and the ascertain whether or not it is possible to isol.ste the source (only the high pressure line is equipped with an isolation valve) it is necessary to disable *the bypass valve.
If it is possible to isolate the l
1eak, it would be desirable to continue operating CNS until a time when i
the repairs can more conveniently be made.
If it is not possible to isolate the leak CNS may have to be shut down in order to make the necessary repairs.
Currently, the limiting Cycle 11 fuel thermal limits (Option B) are j
dictated by the feedwater controller failure - maximwn demand (FVCF) event.
The calculated minimum critical power ratio (MCPR) for this event at end-of cycle (EOC) is 1.23 and the corresponding technical specification limit is 1.25 (i.e.,
a margin of 0.02 exists to the technical specification limit to allow for 10CFR50.59 evaluations of l
the cycle specific limits). The WCF transient is analyzed assuming all
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(
three bypass valves are operabic.
Disabling one of the bypsss valves may increase the calculated CPR for the WCF event.
In order to allow-Nebraska Public Power District (NPPD) to investigate the source of the leak and determine if the leak can be isolated, Concral Electric has
)
been requested to perform an assessment of the potentist increase in the i
CPR for the WCF with one bypass valve inoperable.
Based on a review of the current CNS response to the WCF and load rejection without bypass i
events, the maximum increase in the CPR (over the current value) f,or the i
FWCF event. with one bypass valve inoperable is expected to be significantly less than 0.10.
Consequently, administrative 1y limiting the operatin5 CPRs above 1.33 (0.10 over the Cycle 11 calculated value at EOC, Option B) will conservatively ensure that the safety limit MCPR of 1.0/ will noc be violated while operating with one bypass valve CD out of-service considerin5 any of the abnormal transient events J@
previously analyzed for CNS.
88'
-R Prepared by:
mo.
- Mad bu K.F. Cornwell, Senior Engineer OO Application ens ncering Services i
at <
w Reviewed byn.
Ct/h i
ma.m J.F. KlapprothhPrincipal Engineer Licensing and Consulting Services Approved by:
Nl, [W O.L.SozzF,Manfg6r' Application Engineering Services
I E50aM87 4
l CNSS876103*
NEBRASKA PUBLIC POWER DISTRICT j
j l
Sheet of RECORD OF TELEPHONE CONVERSATION 9/21/87 Date Page 1 of 1 320 Time FROM:
G. Horn, J. Meacham, E. Mace, TO:
Name K. Walden. P. Ballinger Name W
0- Lone-I Company NPPD Company USNRC
SUBJECT:
Turbine Bypass Valve - Control Oil Leak TOPICS OF CONVERSATION:
NPPD contacted MRC (Long) regarding the subject concern. Meacham described i
l the problem regarding one of Cooper's three steam bypass valves. Although they are not Tech. Spec'ed, one of the analyzed station transients, feedwater controller failure (see USAR Ch. 14 and current reload analysis), does take credit for steam bypass operation.
i l
l The current status is that the leaking valve is still operable, but following discussions with General Electric, the District feels there is not a safety I
concern if the valve is taken out of service if minimum Critical Power Ratios (MCPR) is maintained at or greater than 1.35.-(The current limit per Tech i
Specs is 1.22).
General Electric has stated, and is providing written confir-l l
mation, that at 1.35 and above, no fuel thermal limits are threatened, regard-less of the transient.
l The proposed course of action is to maintain MCPR at greater than or equal to 1.35 and isolate the valve. If the leak stops, the District, with the aid of Westinghouse, will investigate repairing the leak. If the leak cannot be repaired with the generator on line, General Electric will be asked to rerun the Feedwater Controller failure analysis to determine what impact, if any, is caused by the isolated bypass valve.
Bill Long expressed no concerns, but indicated he would discuss the problem within NRR. The District committed to forward a copy of General Electric's 1.35 MCPR recommendation to Mr. Long and to inform Region IV of its in-tentions.
The conversation closed with Mr. Long's agreement that the District could proceed as planned and that he would also discuss the problem with Region IV personnel.
7h 4
&Mn G, G. Horn
{
Division Manager of Nuclear Operations GRH:ya DISTRIBUTION:
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j 1
F.50a de7 NEBRASKA PUBLIC POWER DISTRICT j
. Enclosure 3 Sheet of Page 1 of 1-RECORD OF TELEPHONE CONVERSATION 9/21/87 Date Time 1350 FROM:
G. Horn, J. Meacham, E. Mace.
TO:
Name K. Walden, P. Ballinger Name Jaudon, Westerman, Cagliardo Company.
Company USNRC - Region IV NPPD
SUBJECT:
. Turbine Bypass Valve - Control Oil Leak TOPICS OF CONVERSATION:
Following a discussion with the District's NRC Project Manager on this subject, NPPD contacted Region IV.
Heac, ham described the problem regarding one of Cooper's three steam bypass valves. Although they are not Tech.
Spec'ed, one of the analyzed station transients, feedwater controller failure (see USAR Ch. 14 and current reload analysis), does take credit for steam bypass operation.
The current-status is that the leaking valve is still operable, but following discussions with General Electric, the District feels there is not a safety concern if the valve is taken out of service if minimum Critical Power Ration (MCPR) is maintained at or greater than 1.35.~(The current limit per Tech Specs is 1.22).
General Electric has stated, and is providing written confir-mation, that at 1.35 and above, no fuel thermal limits are threatened, regard-less of the transient.
The proposed course of action is to maintain MCPR at greater than or equal to 1.35 and isolate the valve. If the leak stops, the District, with the aid of
{
Westinghouse, will investigate repairing the leak.
If the leak cannot be repaired with the generator on line, General Electric will be asked to rerun the Feedwater Controller failure analysis to determine what impact, if any, is caused by the isolated bypass valve.
Mr. Jaudon expressed no concerns, but indicated he would discuss the problem with NRR. The District committed to forward a copy of General Electric's 1.35 MCPR recommendation to Region IV (if the document was not proprietary).
The conversation closed with Mr. Jaudon's agreement that the District could proceed as planned.
Mr. Jaudon also suggested that the District may want to consfder forwarding an informational LER on this subject.
I l Cw G.
Horn Division Manager of Nuclear Operations i
GRH:ya DISTRIBUTION:
Participants