Example 13: Tailoring of Unreviewed Safety Question Process to Environmental Restoration Activities

DOE-STD-1120-2005/Vol. 2

analyses to confirm assumptions used in the derivation of TSRs and to verify inventory certainties. Once

the six process vessels were removed and all required confirmations and approvals completed, the

limiting conditions of operations (LCOs) contained within the TSRs that were associated only with this

"mode" were no longer applicable. Additional TSRs were applicable during the subsequent "mode,"

including more detailed characterization of the pipe trench. Hold points were used throughout the

activities to ensure that assumptions, laboratory data, analyses, and approvals were obtained prior to

authorizing work.

WORK EXECUTION

Example 13: Tailoring of Unreviewed Safety Question Process to Environmental Restoration

Activities

The Unreviewed Safety Question (USQ) process has retained the focus on protecting hardware that is

important to safety (Equipment Important to Safety). This example provides one way that responses to

the USQ questions on Equipment Important to Safety have been tailored to fit ER activities.

DOE G 424.1-1, Implementation Guidance for Use in Addressing Unreviewed Safety Question

Requirements, identifies seven questions that are an expansion of the three general questions identified in

10 CFR 830, Subpart B. Standard questions # 3 (probability of a malfunction of equipment important to

safety), # 4 (consequence of malfunction of equipment important to safety), and # 6 (malfunction of

equipment important to safety of a different type) all involve the issue of change impact to hardware

(equipment important to safety). These questions are focused on some form of hardware barrier

mitigating an undesirable event. Environmental restoration activities typically have a stronger reliance on

administrative controls and company level safety management programs as opposed to safety SSCs

Recognizing that administrative controls can provide a level of importance similar to that of safey SSCs

(see DOE-1186), one DOE site expanded their responses to USQD questions to better fit ER activities.

The responses address the standard "equipment important to safety" (e.g. there are none) and expand the

response to cover "controls important to safety" that replace the traditional hardware reliance. A typical

response to question # 3 is provided below as an example of the tailoring that has been used.

(3) Could the proposed change or as-found condition increase the probability of a malfunction of

equipment important to safety previously evaluated in the facility's safety analyses?

Yes

B-13