Generic Guidance on Preplanned Alternative Method for High Range Noble Gas Monitoring
See the memorandum from E. L. Jordan to R. A. Scarano dated October 22, 1985. This memo states that preplanned alternate methods of determining noble gas releases as backups to high range noble gas monitors need not be continuous monitors. Local radiation survey instruments or meters on the effluent line are an acceptable preplanned alternate method.
A request was made for generic guidance during a review of the proposed alternative method (PPAM) for determining noble gas releases proposed by Palo Verde Nuclear Generating Station (PVNGS). The PPAM was required by PVNCS Technical Specifications to be used as a backup for the High Range Noble Gas (HRNG) monitors required by NUREG-0737, Item II.F.1.
It was Region V's position that a backup to the HRNG monitors must be a continuous monitor with a comparable range. However, based on discussions with cognizant members of NRR's staff, it was found that the PPAM does not necessarily have to be a continuous monitor.
NRR also stated that the current form of the Technical Specifications began with a memorandum from D. G. Eisenhut to T. E. Murley dated October 20, 1980. This memo proposed that provisions for monitoring noble gas in Standard Technical Specifications be relaxed. Prior to this time, the action statement for an inoperable HRNG monitor required a plant shutdown. No technical basis could be found for the shutdown requirements; therefore, the provision for initiating a PPAM was substituted in the action statement. The intent of the revised action statement was to ensure that the licensee devised a feasible method to monitor noble gases as a backup to the HRNG monitors, but not to require redundant HRNG monitors.
Prior to the issuance of NUREG-0737, interim requirements for monitoring high range noble gases were specified in NUREG-0578. During its review of these interim measures, NRR accepted a method of HRNG monitoring if the licensee could demonstrate that it was adequate to characterize the radioactive release without exceeding the dose limits of GDC-19. Many licensees found that the simplest method was to install a local radiation survey instrument or meter on the effluent line. This method was preferable to grab sampling since it is less dose intensive and easier to shield. For many plants, the interim system installed to meet the requirements of NUREG-0578 now serves as the PPAM. However, taking the position that this is the only acceptable proposal is a significant deviation from the position established by NRR.
Regulatory references: NUREG-0737, Technical Specifications
Subject codes: 7.3, 9.1, 12.16