[Federal Register Volume 64, Number 208 (Thursday, October 28, 1999)]
[Notices]
[Pages 58107-58108]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-28227]


-----------------------------------------------------------------------

NUCLEAR REGULATORY COMMISSION


Selection of Sample Rate and Computer Wordlength in Digital 
Instrumentation and Control Systems, Availability of Draft NUREG for 
Comment

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of availability.

-----------------------------------------------------------------------

SUMMARY: The Nuclear Regulatory Commission is announcing the completion 
and availability of Draft NUREG-1709, ``Selection of Sample Rate and 
Computer Wordlength in Digital Instrumentation and Control Systems,'' 
dated August 1999.

ADDRESSES: Draft NUREG-1709, is available for inspection and copying 
for a fee at the NRC Public Document Room, 2120 L Street NW (Lower 
Level), Washington DC 20555-0001. A free single copy of Draft NUREG-
1709, to the extent of supply, may be requested by writing to 
Reproduction and Distribution Services Section, OCIO, U.S. Nuclear 
Regulatory Commission, Washington, DC 20555-0001.

FOR FURTHER INFORMATION CONTACT: Terry Jackson, Division of Engineering 
Technology, Office of Nuclear Regulatory Research, U.S. Nuclear 
Regulatory Commission, Washington, DC 20555-0001. Telephone: 301-415-
6486.

SUPPLEMENTARY INFORMATION: Digital sampling of analog signals adds two 
types of errors, aliasing and finite wordlength error, to the sampled 
version of the signal. Aliasing is characterized by high frequency 
components misrepresented as low frequency components in the sampled 
signal. It is greatly influenced by the sample rate, and may lead to 
degraded performance in monitoring, alarm, control, and protection 
systems. Since

[[Page 58108]]

computer wordlengths are finite in length, digital systems are limited 
in their capability to represent real number values. Finite wordlength 
errors related to round-off, truncation, and data conversion have the 
potential to adversely impact the performance of digital 
instrumentation and control (I&C) systems.
    The Office of Nuclear Regulatory Research has investigated the 
technical bases and review guidance regarding aliasing and finite 
wordlength errors in nuclear facilities. Hazards associated with these 
errors are minimized through proper design and selection of sample 
rates and computer wordlengths. Draft NUREG-1709 provides the 
regulatory background, theoretical information, practical issues, best 
engineering practices, review guidance, and examples associated with 
sample rate and computer wordlength selection. This information is used 
by NRC staff to identify proper treatment of aliasing and finite 
wordlength error in digital I&C systems.
    While draft NUREG-1709 is intended for NRC staff use, the NRC 
realizes that licensees and vendors may reference the NUREG for their 
particular I&C development. Because of its impact on I&C development, 
the NRC is requesting comments on draft NUREG-1709. The comment period 
will last until March 1, 1999, at which time the NRC will consider the 
comments and pursue a final version. To send comments on draft NUREG-
1709, refer to the comment instructions at the front of the report. 
Comments may also be sent to the NRC Home page, as detailed below.

Electronic Access

    Draft NUREG-1709, is available electronically by visiting NRC's 
Home Page (http://www.nrc.gov) and choosing ``Reference Library,'' then 
``NRC (NUREG) report number,'' then ``NRC Staff Reports,'' and then 
``NUREG-1709.'' Instructions for sending comments electronically are 
included with the document at the web site.

    Dated at Rockville, Maryland, this 24th day of August, 1999.

    For the Nuclear Regulatory Commission.
Sher Bahadur,
Chief, Engineering Research Applications Branch, Division of 
Engineering Technology, Office of Nuclear Regulatory Research.
[FR Doc. 99-28227 Filed 10-27-99; 8:45 am]
BILLING CODE 7590-01-P