The NRC made some rule changes in the mid-1990’s that simplified a critical component of a nuclear power plant’s licensing basis. This reduced the paperwork burden on both the NRC and the sites. It also gave birth to a new kind of licensing basis document.
The technical requirements manual is a document that is part of the plant’s licensing basis, but any changes to it do not have to be approved in advance by the NRC like they do with changes to the Technical Specifications. In other words, a license amendment request is not needed to modify the TRM.
The Tech Specs are governed by 10 CFR 50.36. Other associated documents find their origin in this section too, such as the Tech Spec Bases and the TRM.
DEVELOPMENTAL HISTORY
The TRM came about because of a rule modification the NRC made in 1995. The original technical requirements definition included in 10 CFR 50.36 was vague, created originally to implement a certain section of the Atomic Energy Act. It required, simply, that the technical specifications be derived from analyses and evaluations supplied in the safety analysis report (SAR) and its later revisions (UFSAR).
Ultimately, plants began putting much more than the minimum required information in the Tech Specs. Since the Tech Specs (TS) require license amendment requests to be reviewed and approved by the NRC prior to the associated mod package being implemented, and since the TS contained details extraneous to the minimal TS requirements, the NRC became inundated by the number of license amendment requests it received. As you can imagine, plants were requesting permission to make changes that they really didn’t have to ask permission for. The NRC explained this in the background information published in association with the 1995 rule change:
This extensive use of technical specifications was due in part to a lack of well-defined criteria (in either the body of the rule or in some other regulatory document) for what should be included in technical specifications. Since 1969, this use has contributed to the volume of technical specifications and to the several-fold increase in the number of license amendment applications to effect changes to the technical specifications. It has diverted both NRC staff and licensee attention from the more important requirements in these documents to the extent that it has resulted in an adverse but unquantifiable impact on safety. (Emphasis added.)
FOUR SCREENING CRITERIA
The first attempt to simplify the TS requirements was initiated by the NRC in the early 1980’s, but it took until the end of the decade and into the beginning of the 1990’s to draw up a final formulation of the simplifying criteria. The NRC, in conjunction with industry groups, came up with four criteria that would more clearly and precisely define what requirements should be left in the Tech Specs. Those criteria are listed in 10 CFR 50.36 and are as follows:
- Installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary.
- A process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier.
- A structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier.
- A structure, system, or component which operating experience or probabilistic risk assessment has shown to be significant to public health and safety.
The focus of these criteria are the plant’s limiting conditions of operation (LCOs). Any LCOs that did not meet any one of these criteria could be removed from the Tech Specs. The NRC explained:
LCOs that do not meet any of the criteria, and their associated actions and surveillance requirements, may be proposed for relocation from the technical specifications to licensee- controlled documents, such as the FSAR.
This is how the technical requirements manual (TRM) was born. Many of the extraneous Tech Spec requirements were relocated into this new central location, often with references to associated Tech Specs, to assist operators in performing their daily requirements. Just because these requirements could be removed from the TS did not mean they could be disposed of; operators still needed to ensure these requirements were enforced in their daily routines, so bundling them into a single, clearly written document was intended to make their job easier.
The NRC’s primary thrust in making this rule change was to increase public safety. It stated that “the Commission believes that implementation of the criteria contained in this rule will produce an improvement in the safety of nuclear power plants through the use of more operator-oriented technical specifications, improved technical specification bases, reduced action statement induced plant transients, and more efficient use of NRC and industry resources.”