ML20029C180
| ML20029C180 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/09/1990 |
| From: | Morgan W COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9103260379 | |
| Download: ML20029C180 (2) | |
Text
c
') 1400 Opus Placo Cimmonrealth Edis::n i
,\\
/' Down:rs Grove, Illinois 60515 November 9,1990 Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission Region ill 799 Roosevelt Road Glen Ellyn,IL 60137
Subject:
LaSalle County Station Units 1 and 2 Response to I.R. 373/90022 and 374/90023 HR0_RocketMosl0:313JtadE0:374
Reference:
(a) M.A. Ring letter to C. Reed dated October 11,1990.
Dear Mr. Davis:
This letter is in response to the NRC special safety team Inspection conducted by Messrs. M.J. Kopp and G.M. Hausman of your staff on September 17 through September 21,1990 at LaSalle County Station. The purpose of this inspection was to follow up unresolved items areviously identified relative to the implementation of commitments pertaining to legulatory Guide 1.97.
Refer.sce (a) indicated that certain activities appeared to be in deviation from commitments which were made in previous correspondence with the Commission. The Commonwealth Edison Oompany response to the identified deviation is provided in the following attachment.
If you have any questions regarding this matter, please contact this office, i
Very truly your.=,
b
,. Morkan Nuclear Lic' sing dministrator WM:Imw ZNLD607/11 l 0 91 e2 ggg g !!8173 t
F,
- a
.Sf.l
- e s x
- DEVIATION -
Regulatory Guide (RG) 1.97, Revision 2, Section C. Paragraph 1.3.1.b, requires for :
--Category 1 instrumentation that redundant or diverse channels be electrically.-.
independent and nhysically separated from each other and from equipment not l
. Independence of Electric Systems," up to and including any isolation device.y classified importam to safety in accordance with Regulatory. Guide 1.75,."Ph Contrary to the above, as of So stember 21,1990, resistors, which are not acco stable
. Isolation devices because they lave not been adequately tested, were used to solate RG 1.97, Category 1 reactor vessel leve! instrument loon LT 1(2)B2126BA from the nonsafety-related Startrec system, i
RESPONSE
1.
The Reason for the Deviation:
Commonwealth Edison Company '(CECO) does not agree that the current configuration for the reactor vessel level instrument loop (1/2B21 NO26BA is a -
deviation from LaSalle County Station's commitment to Regulato Guide G) 1.97. It is our poshion that this configuration meets LaSalle Cou Statio e '
electrical separation criteria which meets the roc uirement of Regu atory Guide
'1.75, Rev.-1 with exceptions as noted in Appenclx B of the LaSalle County FSAR.
. Rev.1 of RG 1.75 endorses IEEE Standard 3841974. Section 3 of -
lEEE-384-1974 defines an isolation device as 'a device in a circuH which prevents-malfunctions in one section of a circuit from causing unacceptable influences in -
other sections of the circun or other circuits".-. Further, IEEE-384 Indicates that -
analysis'or testing can be used to demonstrate that Class 1E circuits are not '
Calculation No. CID MISC-08)
(degraded below an acceptable level. Our analysis (degraded below an accept shows that the Class 1E instrument loop will not be level due to a failure in the Startrec System. Therefore, it is our position that the -
22K resistors adequately function to isolate the Non-class.1E Startrec System from' the instrument loop for Reactor Vessel Level Transmitter 1/2B21-NO26BA.
~
2.
The Corrective Actions that have been Taken and tho' Result Achieved:
3
- An analy' sis (Calculation No. CID-MISC-08) was completed which shows that thei
?
Class 1 E circuit will not be degraded below an acceptable level due to a f ailure in the Startrec System. This analysis was submhted for the NRC's review wHh -
- CECO's letter of March 2,1989, from W.E. Morgan (CECO NLA) to A. Bert Davis
_(NRC).
3.
Tha Corrective Actions that will be Taken to Avoid Further Deviations:
J As indicated above, CECO does not believe the current configuration for the j
reactor vessel level instrument loop is a deviation from LaSa'le County Station's u
commitment to RG 1.97. However, CECO will test the resistors to demonstrate i
they are capable of_ isolation the maximum credible fault.-
'4.
The Date when Your Corrective Actions will be Completed:
CECO will submit the test results to the NRC by April 30,1991.
,