L-2016-127, Technical Specification Special Report - Containment High Range Radiation Monitors Inoperable
| ML16188A195 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/16/2016 |
| From: | Snyder M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2016-127 | |
| Download: ML16188A195 (3) | |
Text
U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re:
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 Date, of Event: Jun~ 2, 2016 JUfrr tr zo16
,-_ ':-Tephnical SpeCificati'on-Special Report C6ntainment High Range Radiation Monitors Inoperable i
L-2016-127 10 CFR 50.36
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The attached special report is being submitted pursuant to the requirements of St. Lucie Technical Specification 3.3.3.1, Action b, Table 3.3-6, Action 15 (Unit 1) and 27 (Unit 2), and Technical Specification 6.9.2. This report provides notification that the containment high range radiation monitors were declared inoperable.
Alternate means of radiation monitoring were implemented in accordance with the Technical Specification ACTION statement.
Please contact us if there any questions on this information.
Sincerely, Michael J. Sqyder Licensing Manager St. Lucie Plant MJS/KWF cc:
NRC Region II Administrator -
St. Lucie Plant NRC Senior Resident Inspector ftoO I Florida Power & Light Company
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6501 S. Ocean Drive, Jensen Beach, FL 34957
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 I.
TITLE Containment High Range Radiation Monitors (CHRRMs) Inoperable.
IL EVENT DESCRIPTION L-2016-127 Attachment Page 1 of2 On June 2, 2016, St. Lucie Units 1and2 were in Mode 1at100% power. A NRC design basis inspection identified that the station's 1997 evaluation of previous CHRRMs industry Operating Experience (OE) (e.g., cable jacket blistering, thermally induced currents, conductor kinking, and coax cable moisture intrusion) had incorrectly evaluated the negative impact on operability of these radiation monitors for some postulated events. At 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, FPL declared the CHRRMs inoperable and entered the appropriate action statements for each Unit. The limiting condition for operation (LCO) for TS 3.3.3.1, Action b, Table 3.3-6, Action 15 (Unit 1) and Action 27 (Unit 2), are essentially the same and state that:
"With the number of channels OPERABLE [OPERABLE Channels - Unit 2] less than required by the Minimum Channels OPERABLE requirement, either restore the inoperable Channel(s) to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or:
- 1) Initiate the preplanned alternate method of monitoring the appropriate parameter(s), and
- 2) Prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within 14 days following the event outlining the action taken, the cause of the inoperability and the plans and schedule for restoring the system to OPERABLE status."
On June 4, 2016 the preplanned alternate methods for monitoring containment radiation levels were implemented in accordance with operator night orders and enhancements made to plant procedure EPG-08, "Monitoring Plant Equipment Important to the Radiobgical Emergency Plan," Attachment 2, "Alternate Monitoring Method with the CHRRM Channels Inoperable."
The CHRRMs are used as one of several diverse methods for evaluating emergency action levels (EALs) for the Loss of Fuel Clad Barrier and for the Potential Loss of Primary Containment Barrier in the Emergency Plan. Unit differences necessitate different strategies for the Loss of Fuel Clad Barrier EAL determined by CHRRMs indication. These preplanned alternate methods use:
the containment isolation radiation monitors (Unit 1 ), or the diverse indications as defined in the EAL table to evaluate for the loss of the fuel clad barrier (Unit 2) (e.g. core exit thermocouples, Dose Equivalent I-131, loss of the core heat removal safety function and entry into emergency operating procedure EO P-15)
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2016-127 Attachment Page 2 of2 The Potential Loss of Primary Containment Barrier EAL determined by CHRRMs indication will be provided in part by the use of the post-LOCA radiation monitors* with equivalent outside containment radiation levels.
In addition to direc1iing Emergency Plan EAL entry conditions as described above, the CHRRMs also support Emergency Preparedness dose and core damage assessment capabilities. However, dose and core damage a,ssessment continue to be functional without reliance on CHRRMs as the pre-e~isting procedures and training for members of the Emergency Response Organization and Operations provide diverse means for obtaining the required information.
There are no automatic functions provided by CHRRMs on either Unit other than annunciation.
III.
CAUSE OF THE EVENT The cause for the CHRRMs inoperability was due to the inadequate late 1990s evaluation of
'industry Environmental Qualification OE specific to coaxial cables used for CHRRMs.
Specifically, the cabling used for the CHRRMs is susceptible to thermally induced currents during rapid temperature changes that bias the indication during the temperature transients.
Additionally, at high temperatures the cabling is susceptible to swelling that allows moisture intrusion which results in declining insulation resistance and inaccurate radiation indication.
Until the permanent corrective actions are implemented, FPL has provided alternate means for CHRRMs indication and emergency response.
IV.
ACTIONS TAKEN Short Term:
Preplanned alternate monitoring was implemented ih accordance with TS 3.3.3.1, Action b, Table 3.3-6, Action 15 (Unit 1) and 27 (Unit 2). Well before the CHRRMS were declared out of service, diverse monitoring methods and other procedures were established and trained upon for dose* and core damage assessment.
Long Term:
Preliminary reviews indicate that the coaxial cable for the CHRRMs needs to be replaced or shielded with a more robust design to restore operability. Constructability reviews will be performed inside containment during the next refueling outages.
V.
SCHEDULE FOR RESTORING SYSTEM Based on the constructability reviews and material availability, an implementation schedule will be developed and the more robust coaxial cable design will be installed within the next two refueling outages for each unit.