ML20062D320

/1T-0 on 780928:reactor Coolant Sys Pressure; Dropped.Rate in Decrease Reached 25 Psig Per Minute. Pressure Decrease Caused by Failed elec-to-air Signal Converter

ML20062D320
Person / Time
Site:	Point Beach
Issue date:	09/29/1978
From:	Greenwood J WISCONSIN ELECTRIC POWER CO.
To:
References
LER-78-010-01T, LER-78-10-1T, NUDOCS 7811210349
Download: ML20062D320 (2)

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September 29, 1978 Mr. James Kappler, Regional Director '

Office of Inspection and Enforcement, Region III 4 U. S. Nuclear Regulatory Commission 799 Roosevelt Road ,

Glen Ellyn, Illinois 60137 Dear Mr. Keppler L

LICENSEE EVENT REPORT No. 78-010/0lT-0 24 HOUR WRITTEN NOTIFICATION

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_tPJ,,IT 2 REACTOR COOLANT _ SYSTEM PARTIAL DEPRESSURIZATION POINT BEACH NUCLEAR PLANT b

Licensee Names WIPBH2 License Number: 00-0000-00 License Type: 41111 Docket Number: 50-301  !

Report Source: L Event Date: 09-28-78

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Event

Description:

At 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> en 09-28-78 it was noted that I reactor coolant system pressure had dropped 35 psig from its I normal operating pressure of 2235 psig during the previous 30 minutes. The pressure continued to drop slowly until 1255 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.775275e-4 months <br /> j when pressure then began dropping at a rate of 25 psig per min-t ute. At 1302 hours0.0151 days <br />0.362 hours <br />0.00215 weeks <br />4.95411e-4 months <br /> a ramp decrease in power level of 54 per ,

minute was manually initiated to prevent an automatic trip via the overtemperature AT trip instrumentation (DNB protection). j

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Since there were no indications of increasing radioactivity levels  !

in containment throughout this entire period, it was postulated .

that a problem with the pressurizar spray valve controls existed i and an operator entered the containment to investigate this possi-  !

bility. At 1316 hours0.0152 days <br />0.366 hours <br />0.00218 weeks <br />5.00738e-4 months <br /> pressurizer spray valve 531B (air-operated, i fail air to shut) was>found partially open despite a manual full l shut signal. Air pressure to the valve operator was relieved and ,

the valve closed. Reactor coolant system pressure began recovery immediately. The problem was traced to a failed electrical-to-air  ;

signal (I/p) converter. The converter was replaced at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />; the spray valve then being returned to service. i

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i Mr. James Kappler 2 September 29, 1978 ,

Unit 2 LER 78-010/01T-0 i i

k The lowest pressurs recorded was 1965 psig. Limiting Condition for Operation, Technical Specification 15.3.1.A.4.A.2 states that pressure may not drop below 2220 psia when nor:nal operating pressure is 2250 psia. Lowest power level reached during the manual ramp down was approximately 165 MWe.

' A Manager's Supervisory Staff review of the situation was conducted immediately following the event and return to full power was [

approved after a complato discuasion. The unit achieved full power at 1420 hours0.0164 days <br />0.394 hours <br />0.00235 weeks <br />5.4031e-4 months <br />, 09-28-78. j-A gross beta-gamma analysis of the reactor coolant system on 09-29-78 h

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disclosed no advarse effects upon fuel integrity following the -l transient nor was there any indication of steam generator primary-to-second ey leakage.

This event is reportable in accordance with Technical Specification '

15.6.9.2.A.2. $

g f/4 AAwd J Greenwood Tetephone: 414/7s5-2321 't i

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