ML17300A825

Special Rept 2-SR-87-008:on 870406,condenser Evacuation Sys Radioactive Gaseous Effluent monitors,low-range RU-141 & high-range RU-142 Declared Inoperable for Greater than 72 H. Water Found in RU-141 Due to Holes in Detector Mylar

ML17300A825
Person / Time
Site:	Palo Verde
Issue date:	05/04/1987
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
192-00199-JGH-T, 192-199-JGH-T, 2-SR-87-008, 2-SR-87-8, NUDOCS 8705120309
Download: ML17300A825 (4)

Text

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'CCESSION NBR: 8705120309 DOC. DATa: 87/05/04 NOTARIZED: NO DOCKET 0 FACIL:STN-50-529 Palo Verde Nuclear Station> Unit 2i Ari zona Pub li 05000529 AUTH. NAME AUTHOR AFFILIATION HAYNES'. Q. Arizona Nuclear Power Prospect (formerly Arizona Public Serv REC IP. NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUB JECT: Spec ial Rept 2-SR-87-008: on 870006> cond enser evacua tion sys radioactive gaseous effluent monitors> low range RU-j41 5 high range RU-142 declared inoperable for for greater th-n 72 h. Mater found in RU-141 due to holes in detector mylar.

DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR ENCL SIZE:

TITLE: 50. 73 Licensee Event Report (LKR) i Incident Rpti etc.

NOTES: Standardized plant. M. Davisi NHR: jCy. 05000529 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 LICITR*,E 1 DAVIS> M 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 1 AEOD/DOA 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1 DEDRO 1 NRR/DEST/ADE 0 NRR/DEST/ADS 1 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEST/ICSB 1 1 NRR/DEST/MEB NRR/DEST/MTB 1 NRR/DEST/PSB 1 NRR/DEST/RSB 1 1 NRR/DEST/SQB 1 1 NRR/DLPG/HFB 1 NRR/DLPG/GAB 1 1 NRR/DOE*/EAB 1 NRR/DREP/EPB 1 1 NRR/DREP/R*B 1 NRR/DREP/RPB 2 2 RR S/ILRB NRR/PMAS/PTSB 1 1 Q FILE 02 1 RES SPEIS> T 1 1 RQN5 FI LE 01 1 1 EXTERNAL: EQM QROH> M 5 5 H ST LOBBY NARD 1 1 LPDR 1 NRC PDR 1 NSIC HARRIS, J 1 1 NSIC NAYS> Q 1 1 NOTES:

TOTAL NUMBER OF COPIES REQUIRED: LTTR 44 ENCL 42

Arizona Nuclear Power Project P.o. BOX 52034 ~ PHOENIX, ARIZONA 85072-2034 192-00199-JGH/TRB/JEM May 4, 1987.

NRC Document Control Desk U.$ . Nuclear Regulatory Commission Mashington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station Unit 2 Docket No. STN 50-529 (License NPF-51)

Special Report 2-SR-87-008 File: 87-020-404

Dear Sirs:

Attached please find a Special Report 2-SR-87-008 prepared and submitted pursuant to Technical Specifications 3.3.3.9 and 6.9.2. This report discusses a Radiation Monitoring Unit inoperable greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

If you have any questions, please contact Tom Bradish, Compliance Supervisor at (602) 932-5300, Ext. 6936.

Very truly yours,

& 8/ @=p-J.e G. Haynes

~

Vice President Nuclear Production JGH/TRB/JEM/cld Attachment cc: 0. M. DeMichele (all w/a)

E. E. Van Brunt, Jr.

J. B. Martin R. P. Zimmerman R. C. Sorenson E. A. Licitra A. C. Gehr INFO Records Center 8705120309 870504 PDR ADOCK 05000529 8 PDR

PALO VERDE NUCLEAR GENERATING STATION Radiation Monitoring Unit Inoperable for Greater Than 72 Hours License No. NPF-51 Docket No. STN 50-529 Special Report 2-SR-87-008 This Special Report is being submitted pursuant to Technical Specification 3.3.3.9 ACTION 42b and Technical Specification 6.9.2 to report an event in which a Radioactive Gaseous Effluent Monitor, (Condenser Evacuation High Range Noble Gas Activity Monitor) RU-142, was inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limit for operability was exceeded at approximately 0925 MST on April 9, 1987. Pursuant to Technical Specification 3.3.3.9 ACTION 42a the Preplanned Alternate Sampling Program was initiated to monitor the Condenser Evacuation System.

At approximately 0825 MST on April 6, 1987, Palo Verde Unit 2 was in Mode 5 (POWER OPERATION) when the Condenser Evacuation System Radioactive Gaseous Effluent Monitors, low range RU-141 and high range RU-142, were declared inoperable for performance of Surveillance Test 36ST-9SQ07 (Radiation Monitoring Calibration Test for New Scope Process Monitors). During the performanc'e of 36ST-9SQ07 approximately .5 inch of water was found in RU-141 detector cave assembly. The cave assembly is constructed to shield the detector from external radiation. External radiation is that radiation not being monitored as part of the process stream; in this case, not part of the sample flow.

The detector was cleaned but would not calibrate. This was due to pinholes in the detector mylar which permitted light to leak into the detector. The Mylar is installed to prevent light from impinging upon the scintillation crystal. The scintillation crystal is a material that produces light when subjected to a radiation field (i.e.

Beta radiation). If the mylar is perforated, light will be permitted to enter and cause increased output from the detector giving an erroneous high reading. It was determined that the pinholes were caused by errosion of the mylar by the water.

The root cause of this event is attributable to water collection in the detector cave assembly. The water collection was caused by condensation of the moisture in the sample flow which can reach 100 percent humidity. There is a temporary moisture trap installed in the sample flow line which is currently under evaluation to determine its effectiveness. This was the first evidence of moisture passing by the moisture traps since its installation. On April 9, 1987 the detector was removed from RU-141 and a new detector was installed. The new detector was calibrated in accordance with an approved work control document.

The monitor remained inoperable until April 30, 1987, pending the completion of the manufacture of a detector clamp assembly. The clamp assembly holds the detector in place and is manufactured on site due to the unavailability of the part from the vendor.

On April 30, 1987, the monitor was returned to service after successful completion of the applicable Surveillance Test.

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