ML20216D264
| ML20216D264 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 04/02/1998 |
| From: | Katz R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9804150236 | |
| Download: ML20216D264 (3) | |
Text
. _ _ _ _ _ ___
e Pr/rt:n E. K4Tz Baltimore Gas and Electric Company Calvert Clif ts Nuclear Power Plant Plant General Manager Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4101 April 2,1998 .
U. S. Nuclear Regulatory Commission
, Washington, DC 20555 ATTENTION: Document Control Desk SUIkiECT: Calvert Cliffs Nuclear Power Plant, Unit Nos.1 & 2; Docket Nos. 50 317 & 50-318 Calvert Cliffs Independent Spent Fuel Storage Installation, Docket No. 72 8 Fuel Assembiv Structttral Integrity Event - 10 CFR 72.75 30-Dav Report Baltimore Gas and Electric Company (BGE), holder of Independent Spent Fuel Storage Installation (ISFSI) Materials License No. SNM 2505, submits this report pursuant to the requirements of 10 CFR 72.75(d)(2). Paragraph (d)(2) requires that a written follow-up report be submitted within 30 days of making a non-emergency four-hour notification under Paragraph (b) of the same section. On March 3,1998, BGE made a four-hour non-emergency notification to report a condition that may potentially render the NUllOMS 24P Dry Shielded Canister (DSCyfuel package defective as it is described in the Calvert Cliffs ISFSI Updated Safety Analysis Report (USAR). The following is the information required oy Paragraph (d)(2):
(i) A description ofthe event, including the probable cause and the manufacturer and model number (if applicable) ofany equipment thatfailed or malfunctioned:
The event was discovered during a design basis review of the Calvert Cliffs DSC structural calculations. A document that was referenced in both the Calvert Cliffs ISFSI USAR and the NUTECli (now Transnuclear, Inc.) ISFSI Topical Report to conclude that fuel assemblies maintain structural integrity during a transfer cask drop accident was found not to support such a conclusion. The referenced document is a Lawrence Livermore Lab Report No. UCID-21246,
" Dynamic impact Effects on Spent Fuel Assemblies," dated October 20, 1987. The report evaluates the ability of fuel rod cladding to resist impact loads, but makes no attempt to determine whether or not fuel assembly structural integrity is maintained. An evaluation performed by the Calvert Cliffs fuel vendor, subsequent to this discovery, concluded that fuel assembly structaral integrity is not maintained for vertical drop scenarios, and some plastic ,
defortnation is expected for design basis horizontal drop scenarios, as well. The cause of the g r; event appears to be misapplication of the referenced report, using it as a basis for conclusions beyond those supported by the report. ,y n.
9804150236 900402 PDR S
ADOCK 05000317 4 Q" PDR /
l Ddcument Control Desk l April 2,1998 l Page 2
.- > 4 l
(ii) The exact location ofthe event:
I There was no physical event, hence no location for tue event. The discovery of the issue I discussed above occurred at Calvert Cliffs Nuclear Power Plant where the Calvert Cliffs ISFSI is I located.
(iii) The quantitles, and chemical andphysicalforms of the spentfuel or HLW (high level waste) involved:
The amount of material that would be involved in a postulated drop scenario would be 24 spent i Asea Brown Boveri/ Combustion Engineering 14x14 fuel assemblies.
(
(iv) Date andtime ofthe event: .
I The issue was discovered on February 26,1998.
(v) Corrective actions taken orplannedandthe results ofany evaluations or assessments:
i An evaluation was performed to aJdress the potential effects on canisters scheduled to be loaded l
with fuel from Batches l A/B/C and 2A/B/C. For the purposes of determining operability, the j evaluation considered site-specific decelerat'ons of 51 g for vertical and 31 g for horizontal i drops, as described in the ISFSI USAR. The evaluation showed that there was no plastic deformation of the fuel assembly from a horizontal drop accident, but for both top and bottom end vertical drop accident scenarios, the fuel assembly would sustain structural damage.
However, the evaluation showed that the venical drop accident would not change the fuel rod I center to center pitch; therefore, there would be no adverse effect on criticality. He evaluation also showed that there would be no adverse effect on confinement since the DSC is not breached during a drop. While the fuel assembly would not likely be retrieved in one piece, fuel rods could be retrieved individually along with the remaining fuel assembly components.
These evaluations led to the conclusion that the canisters were operable for the purposes of loading Fuel Batches l A/B/C and 2A/9/C. The evaluation also confirmed that the same holds true for all fuel assemblies previously loaded into the Calvert Cliffs ISFSI. A safety evaluation in accordance with 10 CFR 72.48 will be performed to ensure that the design basis reflects the phenomenology associated with this event.
]
i (vi) The extent of exposure of individuals to radiation or to radioactive materials without I identification ofindividuals by name:
There was no exposure ofindividuals to radiation or to radioactive materials.
I
, Documsnt Control Desk i April 2,1998 Page 3 !
t .- * {
1 i
\
l I
L Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, {
for P. E. Katz Plant General Manager PEK/GT/bjd cc: R. S. Fleishman, Esquire II. J. Miller, NRC J. E. Silberg, Esquire Resi< lent Inspector, NRC Director, Project Directorate I-1, NRC R. I. McLean, DNR A. W. Dromerick, NRC J. H. Walter, PSC 0
l I