ML20147A831

/01T on 780828:During Cooldown of the Reactor,The Containment Bldg Was Ventilated Thru the Purge Supply & Exhaust Valves.Improper Tagging Caused Valves to Be Open & Containment Integrity Not Met. (Encl to 7809190170)

ML20147A831
Person / Time
Site:	Palisades
Issue date:	09/11/1978
From:	CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
References
LER-78-030-01T, LER-78-30-1T, NUDOCS 7809190177
Download: ML20147A831 (3)

Text

- - _ _ _ _ _ - _ - _ _ _ _ _ _ - -

g O , .

Palisades NRC FORM 366 (7 77) U. S. NUCLEAR RECULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK: l l 1

l l l l 6lh (PLEASE PRINT OR TYPE ALL REQUIREO INFORMATION) l o I6 i9l lMLICENSEE

? l I l PCODEI A l L l 1l@iSl0l0l-l0l0l0l0l0l 14 LIC4N64 NUMBER

, 0l0l@26l 4 l 1l1 l 2 il lgl l lg 26 UCENSE TYPE Jo 67 CAT 68 CON'T a

lolil 7 8

,gog 60 g l0 l5l 0l O i 0l 2[5 l5igi 0 l 8[ 2; 8l 7; 8lgl0 l9 l1 l1l 718 lg 61 ooCKET NUM8ER 68 69 74 EVENT oATE 76 REPORT oATE 80 EVENT OESCRIPTION ANO PROBABLE CONSEQUENCES f l o 12 i l During cooldown of the reactor the beginning of a maintenance outage, ,

j g , the containment building was ventilated through the purge supply and exhaust valves. Because three of the valves were in an inoperaOle status

,, ,,, , and the reactor was not in cold shutdown, the containment integrity requirements of TS 3.6.1 vere not met. Upon discovery, the valves i 016 I l g

,o,,,; vere restored to a locked closed condition. Event had no effect on I

public health or safety.

• ^ *

'c5$'s" *^is' co sec"$5s su U'.

ioisi 7 8 9 i s i rl g g g i ci g l v t lou,1Na"VlEsl 10 11 12 l l x;g @s "'o'sg g$ g' 13 18 19 20 EVENT YMR RT

@ LER'RO =g If 2%

I ol 22 l--J 23 l

24 I9 I L_J l i I l'l L--J O

L _J 26 27 28 79 30 33 32 N A oN oNP NT uN " 22 #$s s g oMPo R

l33jg[34X_jg l6Zl@ @@

3 36 l0l0UR$l0 [

37 40

[

di N[gl,oMN lg. gyppfi[gg l5 l el l6agUFACTW"'7 lg 42 43 44 47 CAUSE OESCRIPTION ANO CORRECflVE ACTIONS

,,,o,l Improper tagging of the val s at the time they were rendered inoperable

,, , , resulted in their being opened without the realization that containment l integrity requirements would not be met. The valves have since been

, , , , , , properly tagged.

11 14 I l _ l So lil6l l0'l"Ylt lgl N/A* " " l l l After-the-f$Y"' "*""

• l A!viviry co'0TsNT " ** "

art Aseo e7 Ret:Ast li ie I g g 'ggl N/A AuovNTor AcTivivv l N/A hl Location or Rete Ass @

l

' ensoNNel exposSes "

lil7i l Of"'{0l@@gf"*"9 [

,,Rio~~,t'muh

iinil0;""d'l"0lgf"*WA* O l

'oss o, om o1j.c4[o,Aciurv g "

I' 191 7 8 9 L3@l 10 I go l7l0l 7 8 9 10 l lll ll l 68 66 ' 80

a S'

Attachment to Licensee Event Report 78-030

. Consumers Power Company Palisades Nuclear Plant Docket 50-255 Description of Occurrence:

On August 28, 1978, the plant was taken off-line in order to permit repairs to CRDM seals and to PCP seals. During PCS cooldown, the containment building was ventilated through the purge supply and exhaust valves. Because of leakage problems in a 3-vay selector valve in the air supply system to the T-rings for CVs 1805, 1806 and 1807, these selector valves were bypassed in April 1978.

As a result of this bypass, the T-rings for these valves required manual opera-tion in order to be either pressurized or depressurized. This in turn meant that the valves were inoperable from an autanatic closing / sealing point of view. Because the PCS was at 3050F when the purge valves were opened, the containment integrity requirements of Technical Specification 3.6.1 were not met.

Proximate Cause:

The decision to open the purge valves was prompted by the necessity to ventilate the containment building prior to opening the equipment hatch. The purging requirement was discussed at length dur;ng a plant staff meeting on August 28; however, at that tim 7 none of the staff members present recognised that opening CVs 1805, 1806 and 1807 would render those valves inoperable and thereby lead to a violation of containment integrity requirements. Prior to opening the valves , it was found that the valves had previously been tagged closed. The reason that they had been tagged was to prevent unnecessary usage of the valves in order to minimize the probability of valve failure (these valves have exhibited a high failure rate over the past ceveral years). This tagging, which was performed prior to bypassing the T-ring 3-way valves, was not tied to containment integrity requirements. As a result, tagging clearance was requested and received and the valves were opened.

Probable Consecuences:

All of the containment purge valves would have closed upon receipt of either a manual or automatic closing signal. However, no sealing air would have been supplied to the T-rings of CVs 1805, 1806 and 1807 As a result, a path for leakage through the purge exhaust valves (CVs 1806 and 1805) would have existed until air could have been manually restored to their T-rings. At the time of the occurrence, PCS temperature was 305 F. The corresponding saturation pressure for this temperature is approximately 57 psig. As a result, the energy stored in the PCS was relatively low as compared to that at normal operating temperature and pressure. Consequently, if a loss of coolant ac-cident had occurred at the same time the valves were inoperable, the peak pressure inside containment would have been considerably lower than 55 psig and the corresponding leakage out of containment would, in all probability, have been of a small magnitude. Because of the lowered PCS temperature, it is felt that public health or safety was not threatened.

1 l

l l

1

Attachment to Licensee Event Report 78-030 2 Consumers Power Company , .

Palisades Nuclear Plant l Docket 50-255 Root Cause:

This occurrence could have been prevented by proper tagging of the valves (i.e. ,

tags with statements that valve opening would result in a breach of contate.cnt integrity). When the 3-vay valves were bypassed, che Plant Review Committee dictated that the valves should be tagged. Apparently, the individual i:o was to perform the tagging saw that the valves had previously been tagged (see details in " Proximate Cause" above) and concluded that no additional tagging was needed. As discussed above (Proximate Cause) the tagging which was already on the valves was insufficient to assure containment integrity. The lesson learned, therefore, is that when an item needs to be tagged for reasons different from existing tags, new tags must be issued.

Corrective Action:

The valves were closed and the T-rings pressurized. The valve tagging was modified to reflect the contairment integrity requirements. This occurrence, and the lessons learned, vill be discussed with appropriate supervisory personnel.

When materials are available, the valves vill be repaired in order to restore them to a fully operable status.