ML20211Q995

From kanterella
Jump to navigation Jump to search
Forwards 30-day Written Rept ER-99-12,re Loss of Power to Autoclave Position 1 North & 1 South Process Gas Leak Detection (Pgld) in Bldg C-333-A.Caused by Electrical Short Circuit.Submitted Work Request 501636 for PI SEX-4
ML20211Q995
Person / Time
Site: Paducah Gaseous Diffusion Plant
Issue date: 09/10/1999
From: Pulley H
UNITED STATES ENRICHMENT CORP. (USEC)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GDP-99-1031, NUDOCS 9909160028
Download: ML20211Q995 (5)


Text

e U

USEC f

A Global Energy Company September 10,1999 GDP 99-1031 l

l United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 i

Paducah Gaseous Diffusion Plant (PGDP)

Docket No. 70-7001 Event Report ER-99-12 Pursuant to 10CFR76.120(d)(2), enclosed is the required 30-day written event report pertaining to the loss of power to autoclave position 1 North and 1 South Process Gas Leak Detection (PGLD) in Building C-333-A. The Nuclear Regulatory Commission (NRC) was notified of the event on August 11,1999 (NRC No. 36021).

Any questions regarding this matter should be directed to Larry Jackson at (502) 441-6796.

Sincerely, Howard P ey General Manager Paducah Gaseous Diffusion Plant j

Enclosures:

As Stated cc: NRC Region Ill Office NRC Resident inspector-PGDP l

fG I

f I

9909160028 990910 PDR ADOCK 07007001' C

PDR P.O. Box 1410, Paducah, KY 42001 Telephone 502-441-5803 Fax 502-441-5801 http://www.usec.com OfRces in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC N ;

=

4 Docket No. 70-7001 GDP 99-1031 Page1of4 EVENT REPORT ER-99-12 DESCRIPTION OF EVENT On August 11,1999, at approximately 1350 hrs., the Building C-333-A high conductivity steam alarm was received in the operations monitoring room (OMR). Subsequent to receipt of the alarm, the operators determined that there was no electrical power going to autoclaves 1 North or 1 South.

Absence ~of power to the 1 North and 1 South programmable logic controller (PLC) would prevent initiation of audible and visual process gas leak detection system (PGLD) alarms at the autoclave control panel. This control panel provides local alarms from the PLC. When the PLC lost power PGLD local audible and visual alarms were lost in the Building C-333-A area; in Building C-333 area control room (ACR); and in the Building C-300 central control facility (CCF). Power to the PGLD alarm panel located in the Building C-333-A OMR was not affected; therefore, audible and visual PGLD alarms in the OMR remained operable. At approximately 1350 hrs., the Plant Shift Superintendent.(PSS) was notified and declared the affected PGLD inoperable. At approximately 1424 hrs., a smoke watch was established in the affected area in accordance with Technical Safety Requirements (TSR) Section 2.2.4.1. Additionally, compensatory actions were completed as described in Long Term Order (LTO)98-006, "C-333-A Position 1 Programmable Logic Controller (PLC)," which requires the monitoring of the PGLD alarm panels in the OMR. On August i1, 1999, at 2051 hrs., the Nuclear Regulatory Commission Headquarters (NRC-HQ) operations office was notified as required by 10CFR76.120(c)(2) (NRC No. 36021).

Troubleshooting revealed that en electrical short circuit occurred on pressure indicator (PI) SEX-4, located in the Building C-333-A jet station. The P1 has no safety function and is strictly an operational use piece of equipment. At the time of the event, Maintenance craft personnel were ki wor ng ni the vicinity of the Pl. Self-identification by one of the Maintenance craft personnel revealed that a mechanic inadvertently bumped the PI causing a short circuit inside the PI. The area in which the Maintenance craft personnel were working is limited in space availability. The electrical short circuit blew a fuse in the electrical circuit that supplies alternating current (AC) power to the PLC. The 1 North and 1 South PLC provide local visual and audible alarms, which include the PGLD system. There are no requirements to maintain continuous manning in the OMR, only in the facility; therefore, local area alarms alert personnel located in the immediate vicinity to

-.UF. releases.,

1 l

l 1

e...

Docket No. 70-7001 GDP 99-1031 Page 2 of 4 In'1995, Engineering Service' Order (ESO) (Z92880) was generated and subsequently revised in 1997, for Buildings C-333-A and C-337-A to include an optimum solution which will eliminate dependency on 1 North and 1 South PLC in Building C-333-A, as well as 1 East and I West PLC in Building C-337-A. Work ~ on Section H of the, " System Requirement Document (SRD), ESO Z92880" which incorporates this modification has not been certified for construction.

On August 11, 1999, at approximately 1715 hrs., the fuse in the electrical circuit that supplies power to the PLC was replaced and after post maintenance testing that included testing to ensure that the PLC logic was unharmed, the PSS declared the PGLD system operational.

. Procedure CP3-GP-GPl126, " Conduct of Maintenance - Pre-Job Briefing" is intended to help assure maintenance activities are performed according to facility policies and procedures. Section 6.1.1 gives flexibility to the First-line Manager (FLM) relative to the depth of the pre-job briefing and is commensurate with the complexity of the work activity, risk to personnel and potential challenges to safety system structures, systems and components (SSC). Although the PI is not a safety related SSC, the effect of bumping into the PI adversely impacted the operability of a safety related SSC. In this instance, the pre-job briefing should have included precautions to be taken while working in the limited available workspace in the vicinity of the Pl.

The safety significance of this event was the temporary loss oflocal PGLD system alarms which was identified by operators. Power to the PGLD system panel in the OMR and the OMR alarm bell were not affected, a

CAUSE OF EVENT A. Direct Cause The direct cause for this event was an electrical short circuit that temporarily interrupted electrical power to autoclave position 1 North and 1 South PGLD PLC that supplies remote and local PGLD alarms.

B. Root Cause The root cause for this event was inadequate precautions by Maintenance Craft personnel working in limited workspace areas that impacted surrounding equipment.

i

i l

Docket No. 70-7001 GDP 99-1031 I

Page 3 of 4 C. Contributing Cause The contributing cause for this event was previously identified corrective actions have not yet been implemented. An ESO was submitted in 1995, and subsequently revised in 1997, to eliminate dependency on the autoclave PLC.

CORRECTIVE ACTIONS A. Completed Corrective Actions

1. On May 18,1999, Operations submitted work request no. 501636 requesting that PI SEX-4 be repaired or replaced.
2. On August 11,1999, the wires on PI SEX-4 were terminated to preclude further electrical short circuits and the fuse was replaced.

L

3. On August 12, 1999, Operations completed a walkdown of the remaining PIs located in Building C-333-A and C-337-A to determine whether a potential for additional electrical short circuits existed that were similar to this event. No deficiencies were noted.
4. On September 1,1999, PI SEX-4 was replaced.

B. Planned Corrective Actions

1. By September 23,1999, Maintenance will develop a crew briefing that will include this -

event and reemphasize the importance of ensuring adequate precautions to avoid contact with circuits and devices of operating equipment in limited work spaces.

2. By November 18, 1999, Maintenance will complete a crew briefing of appropriate personnel in accordance with planned corrective action 1, above.

. 3. By March 17,2000, Engineering will issue a conceptual design package that will include a 4

schedule for installation of the ESO Z92880 modification. At this time an update will be provided that will identify the schedule for installation of the completed design.

L

a Docket No. 70-7001 GDP 99-1031 Page 4 of.4

4. By October 30, 2000,' Engineering will issue a certified for construction (CFC) design package to provide for the modifications contained'in section H, System Requirement

. Document (SRD)ESO Z92880.

EXTENT OF EXPOSURE OF INDIVIDUALS TO RADIATION OR RADIOACTIVE MATERIALS

-None l

LESSONS LEARNED Equipment repairs and modifications within limited workspace areas, which could impact safety systems, necessitate proper planning to avoid inadvertently coming into contact / bumping L

surrounding equipment.

l l

l

,