ML20040C376
| ML20040C376 | |
| Person / Time | |
|---|---|
| Issue date: | 01/11/1982 |
| From: | Baer R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Feit R, Johnston W, Rosztoczy Z Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML20040B934 | List: |
| References | |
| NUDOCS 8201270582 | |
| Download: ML20040C376 (4) | |
Text
_
4 a, ar c,,
e UI.'ITED STATES 8,i j y; gi'['%,(
~
NUCLEAR RECULATORY COMMISSION 3.,,. '.:, c,
,_;e reAn uncion, o. c. 20sss o,,.. u. N E j' s
.w,p s
JAt2 11 1983 i0TE T0:
W. Johnston,itRR Zi.osztoczy, l'RR
.R). Fei t, RES J. Aus tin, EDO
~
!!. Haass, !!RR J'. Conway,liRR V. Thomas, IE DRAFT IllFORMATION I;0TICE Oil TEPJill'AL BLOCKS Enclosed is a draft copy of a proposed inferitation notice on terminal blocks.
It was prepared by Pon Feit with in,out from Vince Thomas.
The portions g
prepared by Vince are underlined.
Since IE did the typing of this latest version, we are trans:.litting it to all of the interested partics to expedite distribution.
However, cc=nents cn this draf t should be directed to Ron Feit.
Resolution of comments will be -included in the final issuance -
of the Information i;otice by IE.
-)
{.0 0k?
Bob Baer, IE
Enclosure:
As stated 8201270582 820126 PDR REVGP NRCCRGR PDR
D?.Al T:T!!0!;AS W:4:1/8/82 y,v45 b,vc /^'d'c"M ^ "# h 4
~..
Proposed Information !!ctice Pertaining to Environmental Tests of Electrical Terminal Blocks Discussion This information notice pertains to the results of IEC sponsored research conducted on electrical terminal blocks typical of those utilized in many
!!uclear Power Plants.
The research program v:as conducted at Sandia National Laboratorics in Albuquerque, !.!1. and consisted of approximately 600 individual tests made on enclosed and open terminal blocks of the types used at T!4I-2.
The terninal blocks were subjected to 100% humidity conditions up to 136 F uhich v;ere the conditions experienced by some terminal blocks 9
during the T!*I-2 accident.
(!!ote : To date, there~has been no evidence of terminal block failure which gay have occurred during the _Tjil-2 accident.)
- o tests at dasign basis large LOCA ccnditions were condected.
Terainal block perforcance under the test conditicas was measured by monitoring electrical terminal to ground leakage current with terminal to ground voltages of 120, 240, and 430 volts.
The terminal blocks were installed 10_r@l enclosures with a 6 we.1 pressure relief holk.
These metal enclosures dere mounted in a horizontal olane durino the tests, Some tests were made with containment spray and various contaminants that may be found on terninal block's in nuclear power plants.
The following are some important results of these tests:
(1)
Terminal block failure as evidenced by unstable and increasing' leakage cu rent can be experienced at threshold leakage currents less than 50 ma
~
when exposed to 100% humidity conditions at 186 F.
G i
i
- s
_2 (2)
Some failed terminal blocks performed normally when allowed to dry indicating that post test performance is not a guarantee of performance
[-
during! loss of foolant accident conditions.
(3) The v[lve of leakage current increased with the following:
.I e
l (a) Od*,ortemperature (b) the legrce to Vhich the terminal biccks are directly exposed to the vapor (c) surfiten contamination c
(d) the voltage hatween ter.ainal and ground (4)
Steam cad alcohol cleaning t as found to be effective in restoring failtd ~
L terminal blocks with a small sample of failures for the types tested.
He.'. ever,- it may not-be eficctive and may even result in-deleterious ~.,urfece contamination with some typcs of terminal blocks.
Any cleaning procedure used should be_ verified by the terminal block manufacturer.
~
Guidance i
It is recognized'that cleanliness of terminations and terminal blocks in circuits icoortant to safety is of concern to desioners, constructors, and licensees.
The
\\
of i
cleanliness aspects are addressed in Appendix B.10 CFR 50.rc;&tAens.
These 9
regulations require the licensee to establish appropriate procedures based upon f
manufacturer's and constructor's recommendations, operatino experience, and specific component characteristics to assure that equicment is stored, installed, and maintained in an acceptable state.
To'. this end, several IEEE, ANS, ANSI
)
s og x
St ndards and I RC Ccgulatory Guides are being used by designers, constructors, and operators of power plants which address the installation, cleanliness,'and en-coing asintenance'of Class lE electrical cor.iponents, including terminal blocks.
The Office of Inspection and Enforcement has ceneral inspection procedures which are used by inspectors to monitor ccmpliance with the ebove Standsrds, Guides, and recenandations.
Terminal blocks are specifically a
identified as an example of/ component which must be inspected 'for cleanliness d,rrino construction of the power plant.
Ja_y_ifw of the above, licensecs are reminded that the p_lant creventive
- in+cnsece cropr.c1 in use at ti nir facilities should assure (1) proper 3
pNration of all essential caraconants 'is achieved throuchcut the life of the plant; and, (2) that periodic inspe; tion of those terminations and ___
terminal blocks.for cleanliness and installation integrity is performed fc11 cuing any maintenance activity affectina them.
1
- --