SAFETY ENVELOPE

The OP P manual establishes the safety envelope within which the plant is to be maintained and operated under both normal and abnormal conditions. This manual defines the shutdown states and licensing limits, and specifies the heat sinks and their limits. 

A robust safety envelope requires appropriate attention to the design of the three fundamental safety functions, such diat frrm limits are imposed on the possible consequences of a wide range of accident events. 

A safety envelope is provided that basically encloses the containment, with the exception of the areas above the containment top slab and the drywell head. The containment and safety envelope in conjunction with other safety-related features limit radiological effects of design basis accidents to less than the prescribed acceptable limits. 

The operations of the K-Reactor Purification Area and the K-, L-, and P-Reactor Disassembly Basins have been examined in this BIO to ensure the adequacy of tiie safety envelope, and to develop and promulgate any new requirements ensuing from the Preliminary Hazards Analyses and the Hazards Assessment Documents. The existing K-, L-, and P-Reactor Technical Spedfications were also reviewed. The review revealed the need for new admimstrative controls to preserve the safi ty anatytis assumptions. 

The puipose of this Basis for Interim Operadon (BIO) is to establish an interim safety basis for K-Reactor in Cold Standby and to bound the operations of the L- and P-Reactor Disassembly Basins. This BIO demonstrates safety to ty workers throu adherence to saf management programs. In addition to adho ce to sa management program ti BIO demonstrates safety to co-located workers and the public by identitication of the safety envelope and presentation of the results of qualitative and senii-quantitmive safety analyses (Ref 1 1). The BIO serves as the basis fbr the continued use ofK-Reactor in Cold Standby ti>r tiie puipose of tiie... 

The DOE-approved K-Reactor Techidcal Spedficadons provide spedfic limits and controls to establish a safety maigin within the bounds of the analyzed safety envelope established in the SAR. The Technical Spedficadons define the operating limits and surveillance requirements, the basis, safe boundaries, and management and administrative controls necessary to protect the health and safety of the public. Th minimize the potential risk to workers fi-om the uncontrolled release of radioactive or other hazardous materials and from radiadon exposure due to inadvertem cridcality. - The Technical Spedficadons constitute an agreement or contract between DOE and WSRC regarding the safe operation of the K-Reactor. 

El 1991, the Plant Operating Specifications (POS) C ef 4-22) for K-Reactor were originally issued to spedty the balance of the safety envelope requirements not covered by the K-Reactor Technical Specifications. However, the items for this expanded safety envdope were judged to warrant dmiiar rigor and controls as the Techmcal Spedfications. The POS inocedure is to be used in coiyunction with the Tedimcal Spedfications. Ei 1994, the POS has been updated to reflect K-Reactor in Cold Standby (Ref 4-22). 

Figure 2.7.4 elaborates on this idea. It adds the notion of a defined operational boxmdary which provides a safety margin before one reaches the edge of the safety envelope. This is usually defined by the organisation, based on procedures. Between this and the edge of the safe envelope is another boundary, which shows how far the person concerned is still in control of the process. Once the situation goes beyond this boxmdary of controllability, it is only external or chance factors which can prevent... 

Criterion 7. Application of DiD Definition of events outside of estabhshed safety envelope should include DBTs. DiD (per IAEA definition) is a key element of safety philosophy but not a regulatory requirement in the United States. 

Criterion 10. Safety assessment Definition of events outside of established safety envelope should include DBTs (and) include a QA provision for safety assessments and extended to include operational phase (not just design phase) to cover the changes in design. 

Criterion 14. Design basis for items important to safety Definition of events outside of established safety envelope should include DBTs. 

Criterion 16. Postulated initiating events Rehance on manual initiation of systems instead of automatic action to mitigate the response to an initiating event is allowed only in a limited number of circumstances (eg, fire protection) and definition of events outside of established safety envelope should include DBTs. 

TVM 430 can continuously transmit to the train all the information necessary for its movement and allows continuous monitoring so that the train remains within its assigned safety envelope. 

The fourth criterion assesses the ability of the full complement of plant systems to perform their safety functions. By application of this criterion, the plant is shown to be Within the bounds of the existing safety envelope for SRS reactors. Further, this process aids in identifying specific areas for improving the documentation of the SRS safety analysis. 

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