ML20138N089

Advises of Emergency Condenser Loop 2 Leak,During Previous Operating Cycle.Location of Leak Not Identified Through Testing.Emergency Condenser Operability Maintained,Per Tech Spec 4.1.2(b)

ML20138N089
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	10/31/1985
From:	Frisch R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8511050059
Download: ML20138N089 (3)

Text

._ .- ._ . _ . .

Consumers Power Company General officos: 1945 West Parnali Road, Jackson, MI 49201 + (517) 788-0650 October 31, 1985 Director, Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555

~

DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - TECHNICAL SPECIFICATION INTERPRETATION - EMERGENCY CONDENSER OPERABILITY Big Rock Point Technical Specification 4.1.2(b) requires the emergency con-denser to be operable and ready for service at all times during power opera-tion. However, should one tube bundle develop a leak during power operation, it is permissible to isolate the leaking tube bundle until the next outage.

Both energency condenser tube bundles are required to be available for service during cold to hot plant heatup for power production.

Discussion During the previous operating cycle No 2 cmergency condenser lo'op developed a minor leak which was identified by Xenon analyses of the secondary side water.

At that time, a decision was made to isolate the No 2 loop and an Operations Memorandum was issued to plant operators directing that the control switch for the isolated No 2 loop be placed in the " pull to stop" position (inhibiting automatic isolation) and that the No 2 loop only be used if the No 1 loop failed to operate during an emergency. Prior to isolating the No 2 loop, operability of the No 1 loop was verified.

Investigation into the scurce of leakage was conducted during the 1985 re-fueling outage. The investigation consisted of two leakage tests, one volu-metric examination of the tubes and one surface examination of the inlet /

outlet water box tube sheet. The test results are summarired below.

Hydrostatic Leak Test The primary side of the tube bundle was prer.surized to approximately 109% of normal operating pressure with the secondary side drained. No observable leakage was detected.

m$55 - o0 I LJp OC1085-0017-NLO2

{

1

. - - - . - - - _ _ . _. - . _ _ ~ . _ - . - _ .

. +

Director, Nuclear Reactor Regulation 2 Big Rock Point Plant

. Technical Specification Interpretation i

October 31, 1985 Helium Leak Test Following the hydrostatic leak test, the tube bundle was helium leak l tested by Science Applications International Corporation. The primary side of the tube bundle was drained and pressurized to 105 psig with helium. The secondary side was " sniffed" by use of a vacuum pump and a portable mass spectrometer to detect helium. A manual scan of the tube bundle was performed first, then the " sniffer" was attached to the secondary side manway to detect helium that may have accumulated as a result of a very small leak. No source of leakage was detected by either check even though this test can see changes in helium concentrations as low as 1 ppm.

Eddy Current Testing

, Eddy current testing of the tubes was performed and, consistent with Regulatory Guide 1.121, the data was evaluated against Knight's criteria for tube plugging. Results revealed no tube degradation to the extent that would require plugging. ,

Liquid lenetrant Examination Liquid penetrant examirations were performed on the inlet / outlet water box tube to tube sheet welds and evaluated against 1977S78 ASME Code,Section III, Subsection 5320 criteria. No indications were observed.

Conclusion The four examinations did not identify a source of leakage to the secondary side of the emergency condenser. The methods used represent both conventional ,

and state-of-the-art approaches for leak detection.

Interpretation  !

With the completion of these activities and successful testing of the emer- i gency condenser manway and isolation activation circuits, a recommendation was -

made to the Plant Review Committee (PRC) to return the No 2 loop to service for plant startup. Following review of the leakage investigation results, the l PRC supported the recommendation. Subsequent plant startup was also approved t

on the basis of the following:

F

- Both loops of the emergency condenser will be operable during cold to hot plant heatup as required by Technical Specifications.

- Should minor leakage reoccur following heatup and pressurization of the primary system, the loop could be isolated until further corrective r actions can be identified.

OC1085-0017-NLO2 (

r

, . f 'r Director, Nuclear Reactor Regulation ~ 3 Big Rock Point Plant Technical Specification Interpretation October 31, 1985 The PRC has determined that the above actions do not constitute an unreviewed safety question.

During the discussions, the PRC provided the following guidance to monitor /

evaluate performance of the No 2 loop following plant startup.

- Frequency of sampling will be increased from monthly to weekly with the first sample taken within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after achieving normal system operating pressure. The weekly frequency will be continued until leak tightness of the No 2 loop is verified or the No 2 loop is removed from service due to observed leakage. Following the startup from refueling, it may be diffi-cult to detect Xenon levels in the secondary water analysis for two reasons. First, the leakage, if experienced, may be very small as before and second, the activity of the primary system should be much less since degraded fuel pins from the last cycle have been removed from service.

- Should evidence indicate the No 2 loop is still experiencing leakage, the loop will be isolated as before and the Operations Memorandum covering system operation will be reissued. At this time, further investigation of inspection techniques or other options will be reviewed to facilitate location of the leak and repair of the tube bundle.

These recommendations will be implemented upon return to power operation.

In conclusion, Consumers Power Company 'ias determined that the emergency condenser tube bundles are operable in accordance with Big Rock Point technical specification 4.1.2(b) and that plant startup and power operation may continue.

i L Ralph R Frisch Senior Licensing Analyst CC Administrator, Region III. USNRC NRC Resident Inspector - Big Rock Point Plant 1

k f

OC1085-0017-KLO2 L________.___________._____