ML20212F117
| ML20212F117 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/05/1987 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM 5211-86-2184, NUDOCS 8701090405 | |
| Download: ML20212F117 (3) | |
Text
-
3 GPU Nuclear Corporation g
gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
January 5, 1987 5211-86-2184 Office of Nuclear Reactor Regulation Attn:
J. F. Stolz, Director PWR Projects Directorate No. 6 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Three Mile Island Nuclear Station Unit 1 (THI-1)
Operating License No. DPR-50 Docket No. 50-289 NUREG 0737, II.F.2 Two issues were raised and not resolved at the October ?,1986 meeting relative to redund3nt display for the Reactor Coolant Inventory Trending System (RCITS) and the requirement for redundant channels for the Backup Incore Thermocouple Readout (BIRO).
The purpose of this letter is to address these issues.
RCITS Redundant Display The December,1982 NRC Order required GPUN to install a reactor coolant inventory trending system which conforms to the design parameters specified in NUREG 0737, Item II.F.2 The NRC staff stated during the October 2,1986 meeting that the RCITS does not meet the single f ailure requirement of NUREG 0737, Item II.F.2, Appendix B, item (2) because the signals from the RCITS go through a single multiplexer; thus, a redundant display must be provided.
GPUN considers that Appendix B, item (2), requires a single failure design only for acciifent monitoring instrumentation and supporting features which provide information necessary to determine the safety status of the plant and to bring the plant to a safe condition, and to maintain it in a safe condition following an accident. RCITS does not provide this kind of necessary information, and therefore, the Appendix B, item (2) requirement does not apply.
8701090405 870105 e.
PDR ADOCK 05000289 I" p0F P
PDR i0 GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
t 5211-87-2184 January 5, 1987 The staff has asserted that because an Order was issued to install the RCITS, i
l RCITS must meet all the requirements in NUREG 0737, Item II.F.2.
GPUN concurs that RCITS is required by the Order; we believe that the RCITS meets all the 4
applicable requirements and is adequately designed for its use. As specified in the Order, the addition of RCITS improves the reliability of the plant operators to diagnose the approach of ICC and to assess the adequacy of responses taken to restore core cooling. The addition of the RCITS, coupled with upgraded incore thermocouple instruments and subcooling monitor, provides an ICC instrumentation package which could reduce the likelihood of incorrect post accident operator diagnosis and errors. For low probability events, involving coincidental multiple faults or more rapidly developing small break LOCA conditions, the ICC instrumentation could also reduce the probability of j
incorrect operator diagnosis and subsequent actions leading to a degraded core.
In summary, the RCITS provides additional confirmatory information, and is not 4
necessary post accident monitoring instrumentation.
BIRO Redundant Channels i
The NRC staff has asserted that NUREG 0737, II.F.2 Attachment 1 requires that t
BIRO contain two redundant channels. The basis for this is NRC staff interpretation of the requirements, although the staff has not cited specific words, except as defined in Item (8).
Item (8) specifies that "The primary i
and backup display charnels should be designed to provide 99% availability for 4
each channel with respect to functional capability to display a minimum of four thermocouples per core quadrant..." The NRC staff asserts that since the primary display at TMI uses the plant computer, it does not meet the j
availability requirement, and on this basis the NRC staff maintains that a redundant channel is required for the backup system.
GPUN maintains that use of the computer is required for the primary display to provide the capabilities defined in item (2) of Attachment 1.
The availability of the primary display would not be increased by adding a redundant channel to the backup.
GPUN considers the backup display sufficiently available based on its current design, and therefore in accordance with this requirement. Adding a redundant channel to the backup is not necessary to meet the availability goal for l
BIRO.
i In summary, GPUN considers that Item (8) does not require redundant BIRO channels, that BIRO meets the requirements of item (8), and that its j
availability is assured by our current technical specifications.
l i
i 3
5211-36-2184 January 5, 1987 Moreover, Attachment 1 refers to "a primary operator display" in item (2) and "a backup display" in item (3).
In both items, the term "or displays" is referred to parenthetically, not as a requirement.
Nowhere in Attachment 1 does it state (or even imply) that redundant channels are required for the backup display. GPUN designed and installed BIRO in accordance with the stated requirements and we consider the design adequate for its use.
Sincerely, f
. D. Hu ill Vice President and Director, TMI-l HDH:SK:jh(1389 )
9 Attachment cc:
R. Conte J. Thoma i
i j