L-02-021, Bulletin 2001-01 Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles
| ML020910802 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/28/2002 |
| From: | Myers L FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| IEB-01-001, L-02-021 | |
| Download: ML020910802 (6) | |
Text
Evaluation Report for 2R09 Visual Inspection of Beaver Valley Unit 2 CRDM Penetrations Evaluation Performed by Dennis Weakland February 2002 March, 2002 Revision 1
Introduction The inspection of the CRDM penetrations at Beaver Valley Unit 2 during the 2R09 Refueling outage was performed as part of the commitment made by Beaver Valley in response to Bulletin 2001-01 issued by the NRC. NRC Bulletin 2001-01 was issued as a result of leakage and subsequent identification of circumferential through-wall cracking in the CRDM penetrations at the Oconee Units 1, 2, and 3 and Arkansas Nuclear One power plants. The Industry has investigated the issue and is continuing to perform work to address the concerns under the direction of the EPRI Materials Reliability Project (MRP).
The Beaver Valley commitment in response to NRC Bulletin 2001-01 is to perform a bare metal visual examination of the area on the Reactor Vessel head where the CRDM penetrations meet the outside surface of the Reactor Vessel Head. This examination is performed under the Reactor Vessel head insulation on the exterior surface of the Reactor Vessel Head. The inspection is for the identification of boric acid accumulations that may indicate that a CRDM penetration is cracked through-wall and is leaking.
Purpose and Scope The purpose of the inspection was to identify any evidence of leakage from the CRDM penetration area and Reactor Head Vent piping penetration. The scope of the Beaver Valley Unit 2 inspection of the CRDM penetrations during 2R09 was 100% of the CRDM penetrations and the Reactor Vessel Vent Line penetration.
The identification of visual evidence of leakage in the form of an accumulation of boric acid crystal residue extruding from the penetration area where the CRDM tubing and Reactor Vessel Head Vent piping penetrated the outside surface of the Reactor Vessel Head is the area of focus for the visual inspection. This inspection was performed by Framatome ANP personnel using high resolution remote visual examination equipment and video probes. The inspection was recorded on Super-VHS tape for review and evaluation by the Beaver Valley Site Level III Visual Examiner and the Site Materials Engineer responsible for the inspection.
As noted in the attached visual examination Summary Report (Attachment 1) from Framatone ANP, all examinations were performed by qualified visual examination personnel. The personnel and equipment were qualified using the performance demonstration method. All personnel documentation and certifications are included in the Inspection package maintained by the NDE Department for such examinations.
Inspection Results The bare metal inspection of all the Reactor Head penetrations which consists of the sixty-five (65) CRDM penetrations and one (1) Reactor Head Vent Line from under the insulation found no indication of Boric Acid leakage from any penetration in the Reactor Vessel Head.
None of the penetrations on the Beaver Valley Unit 2 displayed boric acid accumulations of a nature that are indicative of through-wall leakage. As noted in the attached FRAMATOME report, loose accumulations and staining was observed that was directly attributable to leakage from above the insulation.
The inspection found loose boric acid pebbles scattered across the surface of the Reactor Vessel Head with some accumulation of these loose pebbles on the up hill side of several penetrations. Additionally the inspection identified light boric acid stain patterns on several CRDMs indicating leakage from a source above the CRDM Tube to Reactor Vessel Head penetration. In all cases the debris was loose and did not mask the area of examination.
Summary of Results The boric acid accumulations and debris identified were loose in nature and are not associated with leakage from a CRDM penetration. All boric acid accumulations and residue observed was directly attributable to external sources of leakage outside the area of the CRDM penetration.