Taking to the open road in South Texas and Vandellos1 January 1998
Two pioneering projects are showing that nuclear plant process computing can be as open as the office desktop environment, and highly expandable for future upgrades.
The South Texas Project, consisting of two 1250 MWe Westinghouse PWRs, is currently in the midst of one of the largest and most ambitious instrumentation and control upgrade projects yet undertaken at a US nuclear plant. The whole project is scheduled to be complete in the early months of 1999, by which time the existing Proteus Plant Process Computer system (using four Westinghouse P2500 computers) and the existing Emergency Response Facilities Data Acquisition and Display System (ERFDADS), which uses MODCOMP computers, will have been replaced in a phased programme over both units – with minimal impact on plant operation.
The primary function of Proteus is to provide plant personnel with real time information that enables them to assess plant condition at all times, with a secondary function of creating and maintaining a historical record of alarms and other data. The primary functions of ERFDADS are to receive, display, annunciate, alarm and archive plant data, culminating in the Safety Parameter Display System (as stipulated in Nuregs 0696 and 0737), the data from which is transmitted directly to the NRC’s central emergency response data system.
The new system, called the Integrated Computer System (ICS), will take over all these functions, but will also provide for future expansion. ICS includes two independent computer systems, one for each unit, a “stimulated” simulator subsystem (so that the existing full scope simulator can be modified to completely model the new I&C) and an ICS development system.
The South Texas ICS is the first nuclear application of Westinghouse’s OvationTM distributed I&C technology, which aims to achieve a totally open computing environment – as open as the office desktop world – using mainstream, open platforms and standards-based networking, with the total elimination of proprietary operating schemes and vendor-specific hardware platforms. The Vandellos II PWR in Spain, where installation is also now underway, is the second nuclear application of the technology.
At South Texas, thinking about the replacement goes back to around 1990, when the Proteus system was running into spare parts problems and the MODCOMP machines were running out of capacity. The utility was aware that the requirement to run plants better but with less people meant that a major increase in computer power was needed. It also wanted a flexible system that could easily accommodate modifications that might be contemplated in the future.
By 1993-94 the utility had drawn up a specification and was in discussion with a number of vendors, including Westinghouse (original Proteus supplier), NUS (original MODCOMP supplier), SAIC, Bailey, Foxborough and ABB. The field was narrowed down to NUS and Westinghouse. The latter was eventually selected because the utility was attracted by a totally open and totally distributed system, with a high speed (100 megabits/second) FDDI (Fibre Distributed Data Interface) network topology. FDDI, which can handle 200 000 real time points/second from up to 1000 system nodes, is completely off-the-shelf, with wide application and proven track record in mission-critical business and military information network applications.
The order was placed with Westinghouse in August 1995. The logistics of such a replacement at an operating nuclear plant are of course complex, but essentially South Texas unit 2 now has Proteus and ICS operating in parallel, and plans to do the ERFDADS replacement in the first half of 1998, with the existing ERFDADS and ICS operating side by side until the last quarter. Complete handover to the new system will then be completed at unit 2 by the end of 1998, with unit 1 following on, about 3 months behind.
The South Texas system is very large (23 controllers/unit and 100 WEStations on a common data highway). Among the features of the new system are ODBC (open database connectivity), which means system data can be obtained on a PC using similar tools to an office environment, and Java browser capability. Functions include advanced alarm system, BEACON core monitoring and the following nuclear applications: flux map; time average; RCS temperatures; loops in operation; motor monitoring; primary plant performance; redundant measurements; rod supervision; sump level; SPDS/CSF; protection system monitor; BOP performance; setpoint monitor; alarm inhibit logic; delta flux; in-core T/C; leak rate; flow/level corrections; plant mode; radial flux tilt; and engineered safeguards.
As part of the I&C upgrade effort, control room operator consoles are also being remodelled at South Texas. This task, called the Human Interface Modification, was carried out over an intensive two week period in November 1997 at unit 2 and was scheduled for January 1998 at unit 1. Among the reasons for the modification were that, with the old arrangement, primary and secondary operators sat with their backs to the main boards and their areas became congested under emergency plan conditions. Also, the existing consoles would have needed extensive modification to accommodate the new ICS monitors.
Rather surprisingly it was found best to do the change-outs with the units at power rather than during outage. During an outage the operators’ full attention is focused on the complex activities that need to be carried out, and safety-related trains are out of service (although the consoles being replaced are not safety related). During the unit 2 change-out everything did indeed go as planned and control room functions occurred seamlessly amidst the upheaval of construction activity.
THE VANDELLOS II PROJECT
Meanwhile work continues on the second Ovation installation, at Vandellos II (a 1000MWe Westinghouse PWR), where fitting of the new hardware was completed in September 1997. The Spanish had originally planned to upgrade to a Westinghouse WDPF II system. The change-out to Ovation occurred in September 1996.
As with South Texas the aim at Vandellos is direct replacement of the existing Proteus functionality with an open, expandable system, using the existing (Q-line) input/output and field connections (again with potential for Java browsing and open database connectivity). The old and new systems will be run side by side to prove equivalence, and the switchover to Ovation will be on-line or with minimal outage. The installation work is structured to allow maximum work at power. For example parallel wiring of inputs to old and new systems was done during outage, but installation of nuclear application software is done at power.
Relative to South Texas, Vandellos is medium-sized (15 controllers and 18 WEStations). Nuclear applications to be handled by the new system are essentially the same as the US plant, but with two additions to meet Spanish requirements (SVEI and boron follow).