Trip report: Review of the Authorization Basis for Bldg. 371 at RFETS

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DEFENSE NUCLEAR FACILITIES SAFETY BOARD

September 9, 1997

MEMORANDUM FOR:		G. W. Cunningham, Technical Director

COPIES:		Board Members

FROM:		F. Bamdad

SUBJECT:		Review of the Authorization Basis for Building 371 at Rocky Flats Environmental Technology Site

This trip report documents the results of a review by the staff of the Defense Nuclear Facilities Safety Board (Board) of the Basis for Interim Operations (BIO) for Buildings 371 and 374 at Rocky Flats Environmental Technology Site (RFETS), and discussions held with the Department of Energy (DOE) and contractor representatives on September 23, 1997. The staff members participating in this effort were F. Bamdad, R. Kasdorf, R. Warther, and M. Sautman.

Buildings 371 and 374 Authorization Basis. The authorization basis (AB) for Buildings 371 and 374 is a BIO. The Board's staff reviewed the latest revision of this document. Most of the issues raised previously by the staff had been resolved, and significant improvement had been made in the hazard analysis and identification of facilitylevel controls needed for protection of the public. The BIO also provides a systematic approach for performing a process hazards analysis for activities in order to identify the controls needed for worker protection.

An Implementation Plan (IP) for bringing the facility into compliance with the controls and requirements identified in the BIO has also been prepared. It identifies about 130 items that require additional work before the facility can be considered in compliance with controls identified in the BIO. The current schedule in the IP allows the facility to comply with the AB over a 15 month period.

Compliance with Board Recommendation 943. Preparation and implementation of the BIO for Building 371 is a DOE commitment made in the Integrated Program Plan (IPP) for Recommendation 943. The IPP states that a twostep AB development process is planned, with the initial AB in a BIO format and the final in either a Safety Analysis Report (SAR) or Basis for Operations (BFO) format. The contractor representatives attending the meetings stated that the BIO will constitute the nearterm AB for the facility. The BIO, however, will be improved through annual updates to meet the intent of DOE Order 5480.23, Nuclear Safety Analysis Reports. The contractor did not believe developing a new SAR meeting Order 5480.23 was warranted given DOE's goal of decommissioning the building by 2006.

The IPP states that the AB will identify safetyrelated structures, systems, and components based on accident consequences exceeding evaluation guidelines. The BIO identifies several scenarios that do not meet the evaluation guidelines given in the IPP for protection of the public and workers. Additional controls to reduce the consequences of these scenarios, however, have not been identified (or proposed) in the BIO. Among these scenarios are a large fire on the dock a hydrogen explosion in a drum, and a 2000year seismic event. The Board's staff believes it would have been advisable to identify proposed controls (preventive or mitigative measures) for these scenarios in the BIO as committed to in the IPP. Specifically:

		A credible event analyzed in the BIO is a fire on the dock. Thousands of drums and containers will be moving into and out of Building 371 in the near future. The materials on the dock are separated from the outside environment by a rollup door. The ventilation system for the dock was designed to maintain negative pressure with respect to the outside environment, but cannot do so because the ducts do not meet design requirements. The Board's staff believes that if the procedures were modified to close the rollup doors in case of a fire on the dock, and the ducts were modified to provide negative pressure on the dock the consequences of such a fire would be significantly reduced, potentially to an acceptable level.

		All the drums at RFETS have been vented to relieve the hydrogen potentially generated as a result of radiolysis and decomposition of the materials. These vents could be plugged over time, especially for drums containing carbon tetrachloride. This would result in an accumulation of hydrogen in the drums, which could lead to an explosion during their movement. Facility personnel stated that the vents on each drum can be checked before the drum is moved to prevent such scenarios. This preventative measure, however, is not planned because of the additional 15 minutes per drum required.

		One of the potential events analyzed in the BIO with significant consequences to collocated workers is a seismic event combined with fire. Recommendation 943 resulted in an evaluation of Building 371 and several modifications to confine hazardous material during an earthquake. A seismic event combined with fire, however, would defeat some of the facility's safety features (such as fire suppression and highenergy particulate air [HEPA] filters) and result in significant onsite consequences. No additional modifications to reduce those consequences to an acceptably low level have been proposed in the BIO.

Notwithstanding the above concerns, the Board's staff believes implementation of the BIO should commence and will improve the safety of operations performed in Building 371. It may be necessary to make additional modifications to improve safety, as committed to by DOE in the IPP for Recommendation 943, to resolve these concerns.

The Board's staff also reviewed the status of building upgrades. Priority upgrades are basically on track for completion by the end of the year; however, several ventilation system issues need to be resolved by DOE and the contractor. DOE intends to defer the safety margin upgrades by 1 year. The IPP would have allowed this deferral had there been progress on building a new interim storage vault. This vault is no longer planned for construction; however, DOE believes it will be possible to start shipping material off site in the near future, which would obviate the need for the safety margin upgrades. This is a fundamental change in the IPP approach, and needs to be presented to the Board by DOE along with specific dates and milestones.

Future Staff Actions. The Board's staff discussed its findings with DOE Rocky Flats Field Office personnel attending the meeting, and will follow the resolution of the issues raised. Implementation of the controls identified in the BIO will also be followed by the Board's staff.