ML20214U850
| ML20214U850 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 12/04/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20214U820 | List: |
| References | |
| IEB-79-26, NUDOCS 8612090421 | |
| Download: ML20214U850 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION o
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WASHINGTON, D. C. 20056 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO NPF-11 LICENSE CONDITION 2.C(13)
SURVEILLANCE FOR BORON LOSS FROM BWR CONTROL BLADES LA SALLE COUNTY STATION, UNIT 1 DOCKET NO. 50-373
1.0 INTRODUCTION
By letter dated October 6, 1986, Commonwealth Edison (CE) sumbitted its response to IE Bulletin 79-26 Revision 1, " Boron Loss from BWR Control Blades," to satisfy NPF-11, License Condition 2.C(13) for La Salle County Station, Unit 1 (La Salle).
The loss of boron carbide (8 C) by leaching from cracked control blade tubing 4
is addressed in IE Bulletin 79-26, Revision 1, which requires operating BWRs to perform various actions including (1) determining boron depletion for individual control blades, (2) limiting the maximum extent of boron depletion in individual control blades under certain conditions, and (3) conducting shutdown-margin tests and modifying shutdown margin requirements to accommodate the boron loss phenomenon.
2.0 EVALUATION The licensee's response to IE Bulletin 79-26 Revision 1, "Garon Loss from BWR Control Blades, is described as follows:
Item 1.
La Salle is tracking control rod blade exposure history on a monthly basis in accordance with procedure, LTP-1600-29, " Control Blade End-of-Life Projection." Exposure records are maintained on 3-foot segments of each blade (4 segments per blade) on a con-tinuing basis.
Item 2.
Presently, La Salle does not have any control blades which exceed 34 percent boron depletion (all blade segments are less than 10 percent depleted).
A control blade will be discharged prior to exceeding 34 percent boron depletion for any 3-foot segment in accordance with LTP-1600-29.
Item 3.
Prior to the initial startup for La Salle 1 Cycle 2, a single rod i
l subcriticality check (LTP-1600-30) was performed utilizing the analytically the most reactive rod.
In addition, each control blade was individually fully withdrawn to perform CRD testing and criticality was not achieved.
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3-A local subcritical shutdown margin test (LTS-1100-14) was per-formed on September 17, 1986, (prior to the initial criticality for Cycle 2), utilizing the most reactive control rod and a diagonally adjacent control rod. A shutdown margin of 1.259 percent AK/K was demonstrated, which is in excess of the 0.741 percent AK/K (0.38 percent AK/K + R) required by Technical Specifications for Cycle 2.
A beginning of cycle shutdown margin test (LTS-1100-1) was also conducted from the initial criticality on September 17, 1986.
The beginning of cycle shutdown margin was determined to be 2.78 percent AK/K for Unit 1.
A baron loss shutdown margin increment was not required for the Unit 1 Cycle 2 shutdown margin tests because all control blade segments are less than 34 percent depleted (see Item 2). A boron loss increment for future cycles will not be necessary since the General Electric B C original equipment control blades will be 4
discharged prior to exceeding 34 percent boron depletion.
The staff has reviewed the response stated in those three items above.
Based on the review, the staff has found the response meets the requirements of IE Bulletin 79-26 and therefore, is acceptable.
3.0 CONCLUSION
Based on the above finding, the staff concludes that the licensee's response to IE Bulletin 79-26, Revision 1, " Boron Loss from BWR Control Blades," satisfies NPF-11, License Condition 2.C(13), and is acceptable.
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