ML20072U428

Ro:On 830308,turbine Trip & Subsequent Reactor Trip Experienced.Caused by Bumping of Main Steam Stop Valve Relay by Contractor Employee While Working on Control Panel. Cleanup Flow Maintained.On 830306,I-131 Limit Exceeded

ML20072U428
Person / Time
Site:	Point Beach
Issue date:	03/30/1983
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8304110311
Download: ML20072U428 (3)

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Mscomun Electnc mcwm 231 W. MICHIGAN, P.O. BOK 2046, MILWAUKEE, WI 53201 March 30, 1983 Mr. J. G. Keppler, Regional Administrator Office of Inspection and Enforcement, i

Region III U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

DOCKET NO. 50-266 REACTOR COOLANT ACTIVITY LIMITATIONS POINT BEACH NUCLEAR PLANT, UNIT 1 This letter serves as notification of a reportable occurrence at Point Beach Nuclear Plant, Unit 1, in accordance with the Confirmatory Order of November 30, 1979, as modified.

At 1136 hours0.0131 days <br />0.316 hours <br />0.00188 weeks <br />4.32248e-4 months <br /> on March 8, 1983, Unit 1 experienced a turbine trip and a subsequent reactor trip. The trip was apparently caused by the bumping of a Unit 1 main steam stop valve relay by a contractor employee while working on a control panel; this sent a trip signal to the turbino. This event was reported via the Emergency Notification System as required by 10 CFR 50.72. A reactor coolant sample was obtained and analyzed at 1318 hours0.0153 days <br />0.366 hours <br />0.00218 weeks <br />5.01499e-4 months <br /> on March 8. Specific activity was found to be 0.907 pCi/g dose equivalent I-131, which is less than the 1.0 pCi/g dose equivalent i I-131 limitation set forth in paragraph IV.2 of the Confirmatory Order. It was later verified that, according to our administrative procedure for fulfilling the sampling requirements of the Confirmatory Order, the primary coolant sample must be taken between two and six hours after the trip occurred. The initial sample was taken less than two hours after the trip; therefore, another two samples were taken and analyzed at 1640 hours0.019 days <br />0.456 hours <br />0.00271 weeks <br />6.2402e-4 months <br /> on March 8, meeting the time require-ments of the procedure. These samples showed an average specific activity of 1.47 pCi/g dose equivalent I-131. Per the procedure, samples were taken and analyzed in intervals of not greater than four hours until at 2240 hours0.0259 days <br />0.622 hours <br />0.0037 weeks <br />8.5232e-4 months <br /> on March 8 a sample taken showed a specific activity of 0.963 pCi/g dose equivalent I-131. Detailed results of the specific activity analysis obtained on March 8 are as follows:

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F304110311 830330 PDR ADDCK 05000266 S PDR APR 4 g33

. - - - - _ - . =. . _ - -__ -

- Mr. J. G. Keppler -

2- March 30, 1983 Concentrations, pCi/g Isotope 1318 1640 1730 2126 2240 I-131 0.590 1.04* 1.01 0.747 0.706 I-132 0.448 0.477* 0.410 0.221 0.222 I-133 0.874 1.27* - 1.17 0.823 0.766 I-134 0.270 0.0508* 0.0566 0.206 0.276 I-135 0.730 0.866* 0.802 0.470 0.433 TOTAL 2.91 3.70* 3.45 2.47 2.41 Dose Equivalent I-131, pCi/g 0.907 1.47* 1.41 1.02 0.963 i

• Average of two samples taken at'this time.

Based on the times the first and last samples were taken,

' the specific activity of the primary coolant is conservatively-3 estimated to have exceeded 1.0 pCi/g dose equivalent I-131 for approximately 9-1/3 hours.

I On March 6, 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the time the first sample was taken in'which the 1.0 pCi/g dose equivalent I-131 limit was exceeded, the reactor was operated at 1169 MW thermal. power. Load was reduced to 926 MW thermal for approximately six hours on March 7 at the request of the Power Systems Supervisor. The load reduction commenced at approximately 0031 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br />. At 0822 hours0.00951 days <br />0.228 hours <br />0.00136 weeks <br />3.12771e-4 months <br />, the unit was back'at 1169 MW thermal and remained there until the trip at 1136 hours0.0131 days <br />0.316 hours <br />0.00188 weeks <br />4.32248e-4 months <br /> on March 8. Reactor startup commenced later the same day at.1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br /> and at 2122 hours0.0246 days <br />0.589 hours <br />0.00351 weeks <br />8.07421e-4 months <br /> the reactor was'back at 1169 MW thermal.

Cleanup flow 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to finding the limit exceeded i consisted of a 35 gpm flow through the lithium hydroxide mixed bed demineralizer and then through the gas stripper. Cleanup l

i' -flow, including degassing, was maintained during the period of I the_ reactor trip and subsequent return to power. Cleanup flow was doubled to 70 gpm during reactor startup from approximately 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> until 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on March 8.

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Mr. J. G. Keppler March 30, 1983 As of March 1, the fuel burnup by core region was as follows:

Region Average Burnup, MWD /MTU 8A 19,916 10 33,356 11 25,945 12 18,625' 12A 10,053 13 11,299 13A 2,188 This occurrence is an example of icdine spiking following a power reduction or reactor trip. Similar occurrences have been observed frequently in pressurized water reactors in the past.

Westinghouse Topical Report WCAP-8637 dated November 1975 has presented a discussion and analysis of this phenomenon. Subsequent to this reactor trip and iodine spike, the Point Beach Unit 1 primary coolant activity has remained below the 1.0 pCi/g dose-equivalent I-131 limit.

Very truly yours,

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Vice President-Nuclear Power C. W. Fay

' Copy to NRC Resident Inspector