ML20128C216

Special Rept:On 850318,RCS Iodine Radioactivity Spike Occurred.Cause Not Stated.Subsequent Sampling Met Requirements of Tech Spec 3.1.4.RCS I-131 Dose Equivalent Returned to Previously Experienced Levels on 850320

ML20128C216
Person / Time
Site:	Robinson
Issue date:	04/16/1985
From:	Morgan R CAROLINA POWER & LIGHT CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
RNPD-85-800, NUDOCS 8505280223
Download: ML20128C216 (2)

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A0 ROBINSON NUCLEAR PROJECT DEPARTMENT POST OFFICE BOX 790 HARTSVILLE, SOUTH CAROLINA 29550 APR 161985 Robinson File No: 13510 Serial RNPD/85-800 Dr. J. Nelson Grace, Regional Administrator United States Nuclear Regulatory Commission Region II 101 Marietta Street, N. W. , Suite 3100 Atlanta, Georgia 30323 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 LICENSE NO. DPR-23 30 DAY SPECIAL REPORT - REACTOR COOLANT SYSTEM IODINE RADIOACTIVITY SPIKE

Dear Dr. Grace:

This 30-day special report concerning an iodine spike of approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> duration on March 18, 1985, is reported pursuant to Technical Specification 3 1.4 On March 18,1985, at 1409 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.361245e-4 months <br />, the Plant tripped from 100% power.

Subsequent reactor coolant samples indicated an increase in the I-131 dose equivalent. A sample drawn at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> indicated the I-131 dose equivalent was 1.057 poi /gm which exceeded the I-131 dose equivalent reportability limit of 1.0 uci/gm . The subsequent sampling met the requirements of Technical Specification 3.1.4

1. Reactor Power History of the Previous 48 Hours The Plant was operating at 100% reactor power for the 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the reactor trip at 1409 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.361245e-4 months <br /> on March 18, 1985.

2. Fuel Burnup by Core Region Fuel burnup by core regions as of March 31, 1985, is as follows:

Region 11A 22,774.32 MWD /mt' Region 12 12,193.62 MWD /mt' Region 12A 1,9 30.86 MWD /mt*

Region 128 1,49 4.09 MWD /mt" Region 13 504.92 MWD /mt' Region 13A 1,607.70 MWD /mt'

• Megawatt days / metric ton 8505290223 850416 PDR ADOCK 05000261 l

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$' cLt Seric1: RNPD/85-800 Page 2 3 Status of Letdown Demineralizers 48 Hours Prior to Event Reactor coolant letdown flow'through the letdown demineralizers was approximately 105 gpm at the time of the reactor trip. It had been increased from approximately 60 gpm to approximately 105 gpm at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on March 16, 1985.

4. History of Degassing Operations 48 Hours Prior to the Event The Plant did not conduct degassing operations during the previous 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

5. Time Duration When I-131 Dose Equivalent Exceeded Reporting Limit The I-131 dose equivalent limit was exceeded for approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

At 1530,.the activity was 1.057 uci/gm, and~at 1730 had decreased to

.933 uci/gm. By March 20, 1985, the RCS 1-131 dose equivalent had returned to previously experienced levels for this fuel cycle.

If you have any questions concerning this response, please contact Mr. David C. Stadler at- 803-383-4524, Extension 363 ,

Very truly yours, E M General Manager ,

H. B. Robinson S. E. Plant CLWitk/C-819 t.

oc: H. E. P. Krug Document Control Desk >

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