ML17223A258
| ML17223A258 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 08/03/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17223A257 | List: |
| References | |
| NUDOCS 8908110221 | |
| Download: ML17223A258 (2) | |
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t UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C. 20555 ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR PEACTOR REGULATION RELATED TO INTEGRITY ASSESSMENT PROGRAM FOR SPENT FUEL POOL BORAFLEX PANELS FLORIDA POWER 8
LIGHT COMPANY et al.
ST.
LUCIE PLANT UNIT NO.
1 DOCKET NO. 50-335 INTRODUCTION By letters dated June 12 and October 20, 1987, Florida Power 8 Light Company (the licensee) proposed a license amendment to rerack the spent fuel pools at the St. Lucie Nuclear Plant, Unit No.
1 (St. Lucie 1), in order to increase the fuel storage capacity of the pools.
On March 11, 1988, the staff approved the proposed license amendment and issued Amendment No. 91 to Facility Operating License No.
DPR-76 for St. Lucie l.
A hearing was convened in January 1989 by the Atomic Safety and Licensing Board (ASLB).
The ASLB issued its initial decision on May 9, 1989 which ruled that the license amendment permitting the reracking at St. Lucie 1 shall remain in full force and effect as issued.
However, in the deci si on, the ASLB imposed a condition which states:
That in the event that any of the Region 1 Boraflex test coupons are su)jected to gamma irradiation equal to or greater than 1
X 10
- rads, Licensee is directed to prepare within 30 days a
study program to be approved by the NRC staff'nd performed by the Licensee to assess the effect of the irradiation on the integrity of the Boraflex panels.
The study program should include blackness testing or a state-of-the-art equivalent approved by the NRC Staff.
To comply with the ASLB's imposed condition, on July 10, 1989 the licensee submitted an Integrity Assessment Program for the neutron absorbing Boraflex panels in the spent fuel pools at St.
Lucie 1.
EVALUATION The proposed program consists of a one-time Blackness Test (neutron logging) on the Boraflex panels in a total of 20 storage cells in Region 1 of the spent fuel pools.
These 20 storage cells include 13 cells which have been used for spent fuel storage, 5 cells which do not have any stored fuel assembly, and 2 cells which contain long-term surveillance Boraflex coupons.
The Boraflex panels in the 5 storage cells without any stored fuel assembly are unirradiated and will provide the baseline data on Boraflex integrity, that is, no effect on Boraflex due to radiation alone.
The other Boraflex panel~Oto be tested will have received a cumulative gamma radiation dose of about 1 x 10 rads by September 1989.
e9oso 8908110 05p003 pDR
@DOCK pDC tlaximum shrinkage of Boraflex material (an elastomer of methylated polysiloxane filled with finely djgided boron carbide) is predicted at a cumulative gamma radiation dose. of 10 rads by staff's calculations.
This is independently verified by experiments (Bisco Products, Inc., Technical Report No.
NS-1-050 (interim), Irradiation Study of Boraflex Neutron Absorber Interim Test Data, Revision 1, November 25, 1987).
Any defect, such as gap formation on the Boraflex panels, that is associated with its shr inkage would be maximum at this radiation dose level.
A one-time Blackness Test is sufficient, since no further shrinkage of the Boraflex panels is expected at radiation doses over 10 rads.
Prior to performing the actual neutron logging, the licensee will conduct a
calibration and sensitivity study on the test tool, using various known defects in the Boraflex material.
The calibration and sensitivity study will demonstrate that the Blackness Test will be capable of detecting gaps of larger than 0.5 inch in the Boraflex panels.
The staff determined that the proposed program follows good engineering test practice and is capable of assessing the effects of irradiation on the integrity of the Boraflex panels in the spent fuel pools of St. Lucie 1.
The proposed study program, therefore, constitutes compliance with the condition imposed by the ASLB, as.described above.
CONCLUSION On the basis of the above evaluation, the staff concludes that the licensee's Integrity Assessment Program for Boraflex is acceptable and meets the license condition imposed by. the ASLB in its initial decision regarding the St. Lucie 1
spent fuel pool reracking.
Date.
August 3, 1989 Princi al Contributor: