ML19210C479

LER 79-099/03L-0:on 791008,during Boron Injection Heat Trace Test,Unit Failed to Achieve 105 F Temp at One Point on Sys Heat Trace Line.Caused by Sys Design Deficiencies.Test ST 5011.01 Performed Successfully on 791009

ML19210C479
Person / Time
Site:	Davis Besse
Issue date:	11/01/1979
From:	Caba E TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19210C475	List: ML19210C473 ML19210C479
References
LER-79-099-03L, LER-79-99-3L, NUDOCS 7911140319
Download: ML19210C479 (2)

Text

NRC FORM 366 (7 77)

• LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 3 6 l0 l1l l 0lH lD lB lS l1 l@l 0l 0l -l 0l 0l NUMdER Nl PI Fl -l 0l 3l@l 4lLICENSE 23 26 1l1 l1l1l@l TYPE JO $1 LAT bd l@

7 8 9 LICENSEE CODE 14 15 LICENSE CON'T l3 l4 668Q l1 l0 EVENT l0 l8DATE l7 l9 l@l1 l 1 lREPORT 0 l 1DATEl 7 l 980l@

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SO0RN 60 l' l@l 61 0 l5 DOCKET l0 l- l0NUMBER t;9 74 75 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

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O 2 l On October 8, 1979 at 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br /> during the performance of Boron Injection Heat Trace l l

_ jo l3l l Test ST 5011.01, Section 6.01, the unit was unable to achieve the minimum 105 F o 4 temperature at only one point on the heat trace line on the concentrated boric acid l 0 s addition system. This placed the unit in the Action Statement of Technical Specifica1 O s tion 3.1.2.2.a. There was no danger to the health and safety of the public or to l O 7 l station personnel. The flowpath frco the Borated Water Storage Tank was operable. l O a (NP-33-79-ll5) 80 DE CODE SU8C E COMPONENT CODE SUBC DE S ODE l0l9l 7 8 lP lC lh dh l Alh l Z 9 10 11 12 13 ZlZlZlZlZ 18 lh l 'd Zlh J h 20 REVISION SEQUENTI AL 0,CCU R R E NCE REPORT

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35 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l The cause of temperature f ailure is due to design deficiencies in the system. The i i O jilil I addition of cold demin water reduces the temperature in the line and requires time  !

g,l7j l for the heat trace to catchup. ST 5011.01 was successfully performed at 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br /> l

[il3ll on October 9, 1979. Facility Change Request 78-508 was written to investigate l 1 4 I several different ways to imnrove the system. 80 l

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% POWER OTHER STATUS ISCO RY DISCOVERY DESCRIPTION STA S

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLE > ENTAL INFORMATION FOR LER NP-33-79-115 DATE OF EVENT: October 8,1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRLaCE: Boric Acid Flowpath Heat Trace declared inoperable Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2482, and Load (Gross MRE) = 840 Description of Occurrence: On October 8,1979 at 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br />, during the performance of Boron Injection Heat Trace Test ST 5011.01, Section 6.01, hect trace point R2-39 in the flovpath from the concentrated boric acid storage system, was found to be two degrees below the 105 F minimum limit. This required the flowpath be declared inope;a-ble placing the unit in the Action Statement of Technical Specification 3.1.2.2.a.

This requires the inoperable flowpath be made operable within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in hot shutdown within the next six hours.

Designation of Apparent Cause of Occurrence: The test failed because the minimum heat trace temperaure cou}d not be met at one point. The temperatures were low because there was a lot of water added through the line as the plant returned to power following a planned maintenance outage. This water addition is required for boron control in the Reactor Coolant System. Due to deficiencies in the design of this system, the addition of cold demin water reduces the temperature in the heat trace line below the minimum limit. The temperatures had not quite stabilized before the technical specification late date had passed.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The flowpath from the Borated Water Storage Tank (EWST) was operable. The point which failed in the concentrated boric acid addition sys-tem was only two degrees below the 105 F minimum desired temperature and was still well above the temperature that would have caused boron crystalliz 2 tion and possible line blockage for the boric acid involved.

Corrective Action: The heat trace test ST 5011.01, Section 6.01, was successfully performed at 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br /> on October 9, 1979.

Facility Change Request 78-508 was written to look into the possibility of modifying the technical specifications since the much cooler makeup water flowpath utilizes the same section of heat traced piping; or to design a heat exchanger into the system to heat the water before it reaches the heat traced portion of the pipe; or to add additional heat trace to keep the temperatures 2L 105 F even if cold water is injected.

Failure Data: Previous occurrences were reported in Licensee Event Reports NP-33-78-132 and NP-33-79-15.

LER #79-099 1321 TO4