ENS Event | |
|---|---|
17:02 Apr 24, 2013 | |
| Title | Loading Procedure for Isfsi Multi-Purpose Canisters Placed Them in an Unanalyzed Condition |
| Event Description | On April 24, 2013, at 09:02 PDT, Diablo Canyon Power Plant (DCPP) determined that the loading procedure for the independent spent fuel storage installation (ISFSI) multi-purpose canisters (MPCs) placed the MPCs in an unanalyzed condition. The procedure (approved for use in 2009) contained steps to install vent caps on the MPC vents while the MPC contained an air/water mixture. This placed the MPC in an isolated condition without any relief path while water was in the MPC (a condition previously not analyzed in the DCPP ISFSI FSAR).
The MPC vents that prevent MPC over pressurization were disabled while the vent caps were installed with no alternative over pressurization protection provided, therefore the condition is a 24-hour reportable event under 10 CFR 72.75(d)(1). This process was used for 23 casks, beginning in 2009. The amount of time each cask was isolated was approximately 40 - 60 minutes. DCPP expects that no appreciable MPC pressure increase occurred, since the MPC contains an air void, and the activity is performed expeditiously. Based on engineering judgment, a conservative evaluation of the potential pressure rise during this period shows an increase of less than 2 psig. Since the MPC is vented prior to isolation, a 2 psig increase does not challenge the MPC design pressure of 100 psig. Therefore, there is no reason to believe that the integrity of any of the 23 previously loaded MPCs has been challenged at the DCPP ISFSI. This evaluation will be confirmed and documented in a formal calculation as part of issue resolution. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
| Pacific Gas & Electric Co. Avila Beach, California (NRC Region 4) | |
| License number: | SNM-2511 |
| Organization: | Diablo Canyon |
| Reporting | |
| 10 CFR 72.75(d)(1), ISFSI Safety System Functional Failure | |
| Time - Person (Reporting Time:+1.22 h0.0508 days <br />0.00726 weeks <br />0.00167 months <br />) | |
| Opened: | Dan Stermer 18:15 Apr 24, 2013 |
| NRC Officer: | Charles Teal |
| Last Updated: | Apr 24, 2013 |
| 48965 - NRC Website
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Pacific Gas & Electric with 10 CFR 72.75(d)(1), ISFSI Safety System Functional Failure | |
WEEKMONTHYEARENS 489652013-04-24T17:02:00024 April 2013 17:02:00
[Table view]10 CFR 72.75(d)(1), ISFSI Safety System Functional Failure Loading Procedure for Isfsi Multi-Purpose Canisters Placed Them in an Unanalyzed Condition 2013-04-24T17:02:00 | |