07200041/LER-2018-002, 0 for San Onofre Nuclear Generating Station ISFSI Re Spent Nuclear Fuel Transport Conveyance Vehicle Operated Outside Obstacle Clearance Limit
| ML19050A170 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/14/2019 |
| From: | Bosch L Southern California Edison Co |
| To: | Document Control Desk, Office of Nuclear Material Safety and Safeguards |
| References | |
| LER 2018-002-0 | |
| Download: ML19050A170 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 72.75(d)(1), ISFSI Safety System Functional Failure |
| 0412018002R00 - NRC Website | |
text
NN SOUTHERN CALIFORNIA I~
EDISON~
Ari EDISON INTERNATIONAL Company U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Docket No. 72-41 February 14, 2019 Lou Bosch Plant Manager 10 CFR 72.75(d)(1) 10 CFR 72.75(g)
Subject:
LER 2018-002-0, Spent Nuclear Fuel Transport Conveyance Vehicle Operated Outside Obstacle Clearance Limit San Onofre Nuclear Generating Station (SONGS), Independent Spent Fuel Storage Installation
Dear Sir or Madam:
Attached is Licensee Event Report (LER) 2018-002-0, Spent Nuclear Fuel Transport Conveyance Vehicle Operated Outside Obstacle Clearance Limit. The LER is being submitted in accordance with 1 O CFR 72. 75(g) for the notification made in accordance with 10 CFR 72.75(d)(1) for the SONGS Independent Spent Fuel Storage Installation on December 20, 2018.
This letter does not contain any regulatory commitments.
If you have any questions regarding the attached report, please call Mr. Al Bates at (949) 368-6945.
Sincerely, Attachment: LER 2018-002-0 cc:
S. Morris, Regional Administrator, NRC Region IV M. G. Vaaler, NRC Project Manager, San Onofre Units 1, 2 and 3 7EZ-2
- v155 Z-0
- I/VI
- ;5
5NRCFORM U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 366
, the NRG may not conduct or sponsor, and a Jf-""*f'i~
oerson is not reauired to resoond to the information collection.
. Page San Onofre Nuclear Generating Station ISFSI 07200041 1 OF3
- 4. Title Spent Nuclear Fuel Transport Conveyance Vehicle Operated Outside Obstacle Clearance Limit
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Month Day Year Number No.
05000 12 19 2018 2018
- - 002 0
Facility Name Docket Number 05000
- 9. Operating Mode Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
San Onofre Nuclear Generating Station (SONGS) is permanently defueled and is in the process of transferring spent nuclear fuel to dry cask storage in the Independent Spent Fuel Storage Installation (ISFSI).
On December 19, 2018, a review confirmed that the conveyance vehicle which had transported spent nuclear fuel from the fuel storage buildings to the ISFSI had exceeded the seismic analysis obstacle clearance limits to adjacent structures. The Certificate of Compliance (CoC), Appendix B, Section 3.4.15, requires that the conveyance and load does not slide off the haul route or tip over during a Design Basis Earthquake (DBE).
This is a 10 CFR 72. 75(g) 60-day follow-up report to the 24-hour non-emergency event report previously made under 10 CFR 72.75(d)(1) for an important to safety component that failed to function as required by the CoC. A review was conducted by the SONGS staff under the increased focus on the spent nuclear fuel transfer process (LER 2018-001 ). Corrective actions were made to procedures clarifying the clearances.
This report may be retracted dependent on the results of additional analysis. No physical incidents or collisions with structures or obstacles have occurred at any time during the transport of spent nuclear fuel to the SONGS ISFSI. There was no impact on the health and safety of plant personnel, or the public.
NRG FORM 366 (02-2018)
A. Reportable Occurrence SEQUENTIAL NUMBER
- - 002 REV NO.
- - 0 On December 19, 2018, a review by the San Onofre Nuclear Generating Station (SONGS) staff confirmed that the transport conveyance vehicle used to transport spent nuclear fuel from the SONGS Units 2 and 3 fuel storage buildings to the Independent Spent Fuel Storage Installation (ISFSI) had been operated too close to obstacles on the haul route and was less than the separation distance from adjacent structures assumed in the seismic stability calculation. The operation of the conveyance at times did not fully comply with the Certificate of Compliance (CoC). Holtec CoC No. 72-1040, Appendix B, Section 3.4.15 states: "The loaded transfer cask and its conveyance shall be evaluated to ensure under the site-specific Design Basis Earthquake (DBE), that the cask and its conveyance does not tip over or slide off the haul route." No physical incidents or collisions with structures or obstacles have occurred at any time during the transport of spent nuclear fuel to the ISFSI. The review of the transport conveyance vehicle operation resulted from the increased focus by the SONGS staff on the spent nuclear fuel transfer process under corrective actions described in Licensee Event Report (LER) 2018-001, Docket No. 072000-41.
Based on the potential that the conveyance may have been operated outside the limits of the CoC evaluation, SONGS submitted a 24-hour non-emergency Event Report No. 53798 on December 20, 2018, under 10 CFR 72.75(d)(1), "An event in which important to safety equipment is disabled or failed to function as designed when: (i) The equipment is required by regulation, license condition or the certificate of compliance to be available and operable... to mitigate the consequences of an accident.... " A discrepancy in the center of gravity (CG) vertical height was also included in the event report and was
, subsequently confirmed to be within acceptable limits. This 60-day report is submitted under 10 CFR
- 72. 75(g), "Preparation and submission of written reports." This report may be retracted should the results of additional analysis determine the reduced obstacle clearance was acceptable.
B. Initial Conditions Both units at San Onofre Nuclear Generating Station (SONGS) were permanently defueled (Unit 2 on July 24, 2013, Unit 3 on June 28, 2013). Thirty-seven spent nuclear fuel assemblies are contained within each Multi-Purpose Canister (MPC) that is moved from the Unit 2 and Unit 3 spent fuel buildings to dry cask storage in the ISFSI. During the period from January 31, 2018 through August 3, 2018, a total of twenty-.
nine MPCs were moved to the ISFSI utilizing the transport conveyance vehicle. No transfers of spent nuclear fuel have been made since August 3, 2018.
C. Background Information
Holtec International (Holtec) was hired by Southern California Edison (SCE) in 2014 to provide an expanded ISFSI and services for the storage of the spent nuclear fuel from SONGS Units 2 and 3. The ISFSI design employs the Holtec HI-STORM UMAX dry storage vault system. Spent fuel assemblies are loaded into each MPC in the fuel storage buildings. The MPC is placed into a transfer cask, providing personnel shielding and support. The transfer cask is positioned vertically and bolted to a seismic restraint ring on the transport conveyance, a Goldhofer PST/SL-E 16x4 transporter. The MPC and transfer cask are conveyed to the ISFSI following a designated haul route. The cask is removed from the conveyance, transferred to a vertical cask transporter, and the MPC is lowered into the storage vault. Page 2 of 3 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020
"-(}?'4~"o f~\\
~j
.... fl" LICENSEE EVENT REPORT (LER)
CONTl~UATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3D
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR San Onofre Nuclear Generating Station 072000-41 2018 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 0 The seismic stability calculation specified a maximum vertical ground clearance to control the height of the CG to prevent tip over, and a clearance from the side of the conveyance to preclude sliding into obstructions during a DBE, as required by the CoC. The calculation was subsequently revised to evaluate the conditions described in this report.
D. Description of Occurrence As a result of the August 3, 2018 MPC download event (LER 2018-001 ), a review of the appropriate design and licensing documents, and implementing procedures, was conducted by the SONGS staff. During September 2018, craft personnel reviewing the transport process identified that the vertical ground clearance initially set by the procedure was exceeded when the conveyance was adjusted to level the load as it traversed the haul route. The review also identified obstructions, primarily fence gates, concrete "K-rails," and light posts, that were less than the side clearance to the conveyance specified in the procedure.
Subsequently, Holtec was directed to determine the margins of the procedural requirements.
The initial SONGS engineering review concluded there was sufficient margin to accommodate the increase in CG height as the conveyance was leveled along the haul route and requested a revision of the calculation for confirmation. During additional discussions, it was recognized on December 19, 2018 that the reduction in the side obstacle clearance was insufficient to allow for the conveyance to slide without obstruction during a DBE. Consequently, an event report was submitted on December 20, 2018 to address the potential sliding of the conveyance and conservatively included the CG height, while the confirmation was in progress.
E. Cause Evaluation The procedures for the transport of the MPC did not provide sufficient detail to comply with the seismic stability calculation. Additionally, the conclusions of the calculation were not sufficiently detailed to ensure the limits were properly transferred into the implementing procedures. Field personnel did not request additional guidance or clarification of the procedure steps.
F. Completed Corrective Actions
The site procedures for transport of the MPC were revised to provide clear direction on maintaining the CG and side obstruction clearance limits. Additionally, recommended standoff distances have been used to mark exclusion zones for obstacles adjacent to the haul path, and guidelines were established for requesting the evaluation of abnormal or unexpected conditions.
G. Safety Assessment
There was no impact on the health and safety of site personnel or the public. The ISFSI pad containing the storage vaults was not affected by the insufficient obstacle clearance along the transport vehicle haul route.
A revision to the seismic stability calculation for tip over found the variance in CG height was within the acceptable margins. The substantial size and weight of the loaded conveyance minimizes the potential to significantly affect safety. An analysis is in progress to determine if operation of the conveyance with the reduced obstacle clearance was acceptable.
H. Additional Information - Operating Experience SONGS has not had previous issues with the seismic analysis impacting transporting spent nuclear fuel to the ISFSI. Page 3 of 3
NRC FORM 3668 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 3/31/2020 (02-2018)
, the NRC may not conduct or httQ://www.nrc.gov/reading-rm/doc-collections/nur§9s/staff/sr1022/r3D sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITYNAME
- 2. DOCKET NUMBER
- 3. LER NUMBER YEAR SEQUENTIAL REV 05000-NUMBER NO.
- - CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLETO EPIX
' Page 1 of 1