ML20141J174

SER Re Spds.Sys Insufficiently Human Factored to Allow User to Rapidly & Reliably Evaluate All Critical Safety Functions Required by NRC

ML20141J174
Person / Time
Site:	Rancho Seco
Issue date:	04/07/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20141J172	List: ML20141J169 ML20141J174
References
TAC-56526, NUDOCS 8604250362
Download: ML20141J174 (4)

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, ENCLOSURE 1 PLANT, ELECTRICAL, INSTRUMENTATION, AND CONTROL SYSTEMS BRANCH INPUT FOR THE SAFETY EVALUATION REPORT RANCHO SEC0 NUCLEAR GENERATING STATION SAFETY PARAMETER DISPLAY SYSTEM i

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I. Background In response to the Commission's requirements (NUREG-0737, Supplement 1) for a Safety Parameter Display System, the licensee submitted a safety analysis j (Reference 1) for staff review. The results of the staff's review were pub- I lished in a Safety Evaluation Report (SER), which was forwarded (Reference 2) to the licensee.

l The SER contained open issues. The licensee responded (Reference 3) to these open issues and the staff found the information partly acceptable, but identi-fied a new issue. A second request for information was forwarded (Reference 4) to the licensee. The licensee's response (Reference 5) was evaluated by the staff. In addition, during June 19-21, 1985, the staff visited the Rancho Seco Nuclear Generating Station for the purpose of obtaining information on

) the implementation and operation of the Safety Pa,rameter Display System. Our safety evaluation of the i.nformation identified above folicws.

Summary Based on the information provided by the licensee and on the information gathered during the staff's visit to the Rancho Seco Nuclear Generating Station, we conclude that the licensee's SPDS is insufficiently human factored to allow I a user to rapidly and reliably evaluate all of the critical safety function l required by the NRC. We require the licensee to modify the design cf the 1

display system to correct the human engineering discrepancies within the system and to submit the revised design for staff revicw and approval.

8604250362 860407 PDR ADOCK 05000312 P PDR l

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The licensee's design for an SPDS consists of two display systems. Computer driven cathode-ray tubes (CRTs) are used as display devices in each system.

Four critical safety functions consisting of reactivity control, reactor core cooling and heat removal from the primary system, reactor coolant system l integrity, and containm?nt conditions are monitored by the display system j designated as the SPDS. The remaining critical safety function, radioactivity control,is presented on the Digital Radiation Monitoring System (DRMS).

During the staff visit to Rancho Seco's control room, we evaluated the inca-tion of tne SPDS and the location of the DRMS. While we were positioned at the SPDS, which is located on a panel, we were unable to see,the data displayed on DRMS's CRT. Upon relocating to a point in the control room where the DRPS and the SPDS were within one field of view, we were unable te monitor the data on their screens. Furthermore, based on the information provided by the licensee, we were unable to identify any tasks within the design that coordinated the display of data between the SPDS and the DRMs. Thus, based on the control room location of the SPDS and the DRMS, we fail to see how a user o'f these systems will rapidly and reliably evaluate all of the critical safety l functions required of the SPDS.

l A top-level display format within the licensee's SPDS is the post-trip AT0G display. This display format is composed of graphic segments in the form of a pressure versus temperature. plot to show the physical relationship among l primary system hot leg temperature, cold leg temperature, the saturation line for water, and operational limits. Furthermore, interactive graphic techniques are used to provide auxiliary data to the operator without cluttering the dis-play. This display format serves the reactor core cooling and heat removal critical safety function. It was clear, readable, and frequently used by operators.

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The' alphanumeric displ'ay format is the major source of'information 1.n the SPDS for the reactivity control, reactor coolant system integrity, and con-tainment conditions critical safety functions. Process variables and system variable are identified, along with a numerical value. These data are pre-sented in a list form, distributed over four display pages, with a minimum of 20 variables per page, and with no apparent structure. The alphanumeric dis- '

play format is not human factored because it is a difficult lengthy task for a user to evaluate each of the above identified critical safety functions from the scattered, unstructured data list. i e

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e REFERENCES

1. Letter from R. J. Rodriquez, Sacramento Municipal Utility Distri.ct to J. F. Stolz, NRC,

Subject:

Safety Parameter Display System, Safety Analysis and Implementation Plan, dated July 28, 1983, with proprietary attachment. -

2. Letter from G. Rivenbark, NRC to R. J. Rodriguez, Sacramento Municpal Utility District,

Subject:

Safety Parameter Display System, dated July 27, 1984.

3. Letter from J. Mattimoe, Sacramento Municpal Utility District to G. Rivenbark, NRC,

Subject:

Safety Parameter Display System - Request for Additional Information, dated October 2,1984.

a 4 Letter from J. F. Stolz, NRC to R. J. Rodriquez, Sacramento Municipal Utility District,

Subject:

Rancho Seco Nuclear Generating Station -

Safety Parameter Display System, dated July 16, 1985.

5. Letter from R. J. Rodriquez, Sacramento Municipal Utility District to l H. L. Thompson, Jr., NRC,

Subject:

Rancho Seco Nuclear Generating Station j Unit Number 1, Safety Parameter Display System, dated August 30, 1985, i

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