HBL-19-012, Reclassification of Building 47 Waste Management Facility and the Waste Management Facility Storage Pad

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Reclassification of Building 47 Waste Management Facility and the Waste Management Facility Storage Pad
ML19192A340
Person / Time
Site: Humboldt Bay
Issue date: 07/11/2019
From: Welsch J
Pacific Gas & Electric Co
To:
Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
HBL-19-012
Download: ML19192A340 (2)


Text

Pacific Gas and Electric Company*

James M. Welsch Diablo Canyon Power Plant Senior Vice President P.O. Box 56 Generation and Avila Beach, CA 9342 4 Chief Nuclear Officer 805.545.3242 E-Mail: James.Welsch@pge.com July 11, 2019 PG&E Letter HBL-19-012 U.S. Nuclear Regulatory Commission 10 CFR 50.82 (a)(9)

ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-133, OL-DPR-7 Humboldt Bay Power Plant, Unit 3 Reclassification of Building 47 Waste Management Facility and the Waste Management Facility Storage Pad at Humboldt Bay Power Plant

Dear Commissioners and Staff:

In accordance with Humboldt Bay Power Plant Unit 3 (HBPP) License Condition 2.C.(5), Pacific Gas and Electric Company (PG&E) is notifying the NRC at least 14 days prior to implementation of reclassification of a survey area to a less restrictive classification. PG&E intends to reclassify Building 47 (Waste Management Facility (WMF)) and the WMF Storage Pad as depicted in Figure 2-2 of the Defueled Safety Analysis Report and described in Section 2.1.8.17 of the License Termination Plan (LTP) from a Multi-Agency Radiation Survey and Site Investigation Manual Class 1 to lower classifications as described below.

The WMF was built during decommissioning and was classified as a Class 1 area based on the expected decommissioning support activities to be conducted in the area. However, a subsequent decision to direct most of the radiological remediation waste to new soil management structures reduced the anticipated radiological impact on the WMF. The current classification as indicated by LTP Section 2.1.8.17 is a Class 1 survey area.

Visual inspections performed of the areas behind the push walls, which are too small for a person to enter, indicate minimal amounts of spoils and decommissioning debris present. A characterization survey was performed June 6, 2019, to assess the radiological impact to the facility from past operations. The survey focused on the limited access areas behind the south push wall of the structure. Direct measurements collected from the structure wall, push wall, and floor where residual material was sampled indicate less than 1 percent of the building surface Derived Concentration Guideline Level (DCGL) for Cs-137. Media samples of spoils, splatter, and debris material collected from the areas prior to direct measurement collection averaged less than 1 percent of the soil DCGL for Cs-137. It should be noted that of all 15 media samples collected, only one indicated Cs-137, an HBPP plant-derived radionuclide, with a result of 3.24E-01 pCi/g. This result is indicative of global fallout concentrations observed for the area.

Document Control Desk PG&E Letter HBL-19-012 July 11, 2019 Page 2 The WMF will be cleaned prior to final status survey (FSS) and then reconfigured as a warehouse facility for the Humboldt Bay Generating Station.

PG&E proposes to perform a survey to the rigors of a Class 2 survey area on accessible concrete surfaces of the floor and walls. The accessible and limited accessible areas within and behind the push wall respectively have the highest potential for contamination; therefore, activity levels should be similar to or greater than the inaccessible areas behind the push walls. However, static measurements of the inaccessible areas behind the push wall will be collected for statistical comparisons with data collected from the accessible areas behind the push wall as part of the Data Quality Objective process for FSS Survey Design.

PG&E also proposes a survey to the rigors of a Class 2 survey area on the remainder of the area surrounding the WMF, known as the WMF Storage Pad. The downgrading of the WMF Storage Pad from a Class 1 to a Class 2 survey unit is reasonable and appropriate given the above history and the absence of activity distinguishable from background from review of routine contamination surveys performed of this area.

PG&E proposes to perform a survey to the rigors of a Class 3 survey area on metal structures such as interior and exterior siding, side support beams, sheet metal roof, and overhead roof struts in the structure. The classification downgrade of the exterior and interior surfaces of the building structure are reasonable and appropriate given the characterization of the facility and the FSS data collected from the Class 2 and Class 3 survey areas surrounding the structure.

The above changes to classification for FSS of the WMF standing structure and WMF Storage Pad will be reflected in the biennial update to the LTP.

PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter.

If you have any questions, please contact William Barley, Site Closure Manager, at (707) 444-0856.

Sin~

James M. Welsch

"- c;()~ O= J=~s rJ4di Senior Vice President Generation, and Chief Nuclear Officer cc: John B. Hickman, NRC Project Manager Scott A. Morris, NRC Region IV Administrator HBPP Humboldt Distribution NRC Document Control Desk