ML20217A478

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Forwards Revised Event Rept 99-17,for Event Resulting from Determination That Sprinkler Sys Not Capable of Meeting Operability Requirements.Caused by Mineral Deposits.Provided Following Completion of Root Cause Evaluation
ML20217A478
Person / Time
Site: Portsmouth Gaseous Diffusion Plant
Issue date: 10/04/1999
From: Jonathan Brown
UNITED STATES ENRICHMENT CORP. (USEC)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GDP-99-2056, NUDOCS 9910080202
Download: ML20217A478 (5)


Text

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USEC

. A ciob.i en.rry comp.ny October 4,1999 ODP 99-2056 i

U. S. Nuclear Regulatory Commission 1

Attention: Document Control Desk Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)

Docket No. 70-7002 Event Report 99-17, Revision 1 Pursuant to 10CFR76.120(d)(2), Enclosure 1 provides the revised Event Report for an event that resulted from the determination that sprinkler systems associated with the High Pressure Fire Water i

system in the process buildings were not capable of meeting operability requirements at the Portsmouth Gaseous Diffusion Plant. The event report is being revised to include information on the event notifications made since the last report and the results of the sprinkler system walkdowns.

Investigation and testing activities are continuing to determine the root cause and corrective actions for this event. This event report will be revised following completion of these activities. The expected date for submitting the revised report is January 11,2000. Changes from the previous report are marked with a dashed vertical line in the right margin. There are no commitments contained in this report.

Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.

Sincerely,

&JW

. Morris Brown General Manager f

Portsmouth Gaseous Diffusion Plant

Enclosures:

Ad Stated

[f cc:

' NRC Region III Office NRC Resident Inspector - PORTS United States Enrichment Corporation Portsmouth Gaseous Diffusion Plant 9910000202 991004 3x 628, Piketon. OH 45661

- PDR ADOCK 07007002 C

PDR

GDP 99-2056 Page1of4 Event Report 99-17, Revision 1 Description of Event On August 10,1999, at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, the Plant Shift Superintendent was notified that 13 sprinkler systems associated with the High Pressure Fire Water (HPFW) system were not capable of meeting system operability requirements. This condition was discovered as a result of an engineering walkdown ofindividual sprinkler heads that had previously been identified as exhibiting corrosion around the valve seat. Further inspection revealed that the sprinkler heads were not externally l

corroded. The visible ' deposits that appeared to be corrosion were caused by a build-up of dissolved I

solids left by evaporating water that leaked past the seat. The engineering review was conducted j

following the discovery that similar problems experienced at the Paducah Gaseous Diffusion Plant (PGDP) resulted in sprinkler heads being unable to actuate at the required pressure. The failure of i

the HPFW system was reportable in accordance with 10CFR76.120(c)(2). A brief history of events leading to the discovery of this condition is presented below.

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On April 16,1997, the Portsmouth Gaseous Diffusion Plant (PORTS) initiated a walkdown of the fire sprinkler system in response to HPFW piping deficiencies discovered at PGDP. The purpose of the walkdown was to identify any disconnected sprinkler piping branch lines and to find other

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system deficiencies.

1 On June 27,1997, five heads were discovered under ductwork in the X-333 Process Building that

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had a buildup of mineral deposits. Since the impact of mineral deposits on the ability of the sprinkler 1

heads to function was not known, the individual heads were declared inoperable and were replaced.

Six additional heads with mineral deposits were discovered on October 16,1997, and were also assumed to be inoperable. An operability evaluation determined that, because of overlapping coverage of the sprinkler heads and the location of adjacent sprinkler heads, the sprinkler system remained operable, even ifindividual heads would not operate. The walkdown continued through

' November 1997, and additional heads with mineral deposits were discovered.

To determine the impact of mineral deposits on sprinkler head operability,12 sprinkler heads exhibiting mineral deposits were sent to the PORTS laboratory for testing and evaluation. The testing determined that the heads would operate at the proper temperature, but operated at pressures greater than the expected 5 to 7 psig. The available pressures on the sprinkler systems at PORTS L

will vary from 7 to 125 psig depending on the location of the head, the elevation and number of i

heads operating and associated friction losses. The typical pressure available to operate a single head under ductwork in a process building is approximately 105 psig. Since this information provided j

reasonable assurance that mineral deposits did not prevent the heads from operating, sprinkler heads J

having mineral deposits were no longer assumed to be inoperable.

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l GDP 99-2056 Page 2 of 4 Event Report 99-17, Revision 1 Four additional heads with mineral deposits were sent to the manufacturer (Grinnell Corporation) for evaluation and were determined to be within the acceptable range ofoperation. Both the PORTS laboratory and the manufacturer identified that the copper gasket was deteriorated.

On June 2,1999, the annual PGDP Fire Services walkdown of the sprinkler systems found deposits on 81 heads affecting 17 systems (event report ER-99-10). Subsequent inspections found corrosion I

on 18 additional heads. The sprinklers were declared inoperable and TSR actions were taken and replacement initiated. Operational and metallurgical testing of sprinkler heads by Factory Mutual (FM) was requested by PGDP and PORTS. (FM is USEC's insurance carrier and is a nationally recognized testing agency). The test results indicate that the heads work, but some require elevated pressures to activate. Two of twelve PGDP heads activated at 120 psig.

Based upon the PGDP discovery that mineral deposits could prevent sprinkler heads from operating at HPFW pressures, PORTS conservatively declared individual corroded sprinkler heads inoperable pending further evaluation and testing. A walkdown of 27 systems containing sprinkler heads with previously ideritified mineral deposits was performed. The walkdown resulted in 13 systems being declared inoperable because adjacent heads were inoperable. TSR required actions were initiated and 66 heads were changed to restore system operability. As noted earlier, the sprinkler heads that were previously identified as having mineral deposits were believed to be operable because testing indicated that mineral deposits did not prevent sprinkler head operation at HPF W pressures.

Additional walkdowns of process building sprinkler systems were initiated to identify additional sprinkler heads that may have external mineral deposits. On August 19,1999, at 1038 hours0.012 days <br />0.288 hours <br />0.00172 weeks <br />3.94959e-4 months <br />, one additional system was declared inoperable when three adjacent heads having deposits were discovered. The system was repaired at 1407 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.353635e-4 months <br />.

On August 27,1999, at 1452 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.52486e-4 months <br />, five additional sprinkler systems were declared inoperable with two or more adjacent heads unable to meet system operability. All sprinklers were repaired and the systems were declared operable at 0550 hours0.00637 days <br />0.153 hours <br />9.093915e-4 weeks <br />2.09275e-4 months <br /> on August 28,1999.

On August 30,1999, seven additional sprinkler systems were declared inoperable with two or more adjacent heads unable to meet system operability. Six systems were in X-333 and one system was in X-330. All sprinklers were repaired and the systems were declared operable at 1258 hours0.0146 days <br />0.349 hours <br />0.00208 weeks <br />4.78669e-4 months <br /> on August 31,1999.

On August 31,1999, seven additional sprinkler systems in X-333 were declared inoperable with two l

or more adjacent heads unable to meet system operability. All sprinklers were repaired and the l

systems were declared operable at 0608 hours0.00704 days <br />0.169 hours <br />0.00101 weeks <br />2.31344e-4 months <br /> on September 6,1999.

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GDP 99-2056 Page 3 of 4

' Event Report 99-17, Revision 1

' On September 1,1999, fourteen' additional sprinkler systems in X-333 were declared inoperable with l

~ two or more adjacent heads unable to meet system operability. All sprinklers were repaired and the l

systems were declared operable at 0405 hours0.00469 days <br />0.113 hours <br />6.696429e-4 weeks <br />1.541025e-4 months <br /> on September 7,1999.

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. On September 2,1999, four additional sprinkler systems in X-333 and one additional sprinkler l

- system in X-330 were declared inoperable with two or more adjacent heads unable to meet system l

operability. Sprinklers in X-333 were repaired and the systems were declared operable at 0405 hours0.00469 days <br />0.113 hours <br />6.696429e-4 weeks <br />1.541025e-4 months <br /> - I on September 7,1999. Sprinklers in X-330 were repaired and the systems were declared operable l

at 1627. hours on September 17,1999.

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. At 1518 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.77599e-4 months <br /> on September 3,1999, all HPFW sprinkler systems in X-333, X-330, and X-326 were l

, declared inoperable based on the number of corroded sprinkler heads being identified during l

. building walkdowns. All adjacent sprinklers in X-333 were repaired and the systems were declared l

1 operable at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> on September 7,1999. All adjacent sprinklers in X-330 were repaired and l

the systems were declared operable at 1645 hours0.019 days <br />0.457 hours <br />0.00272 weeks <br />6.259225e-4 months <br /> o_n September 17,1999. All adjacent sprinklers l

in X-326 were repaired and the systems were declared operable at 1738 hotrs on September 20, l

1999. Repairs on non-adjacent sprinkler heads are continuing.

l There are approximately 98,000 sprinkler heads in the process buildings at PORTS. The total l

number of sprinkler heads with external mineral deposits discovered between 1997, and September l

'14,' 1999, was approximately 566. The breakdown by building was: 256 in X-333; 242 in X-330; l

68 in X-326.

l The majority of the sprinkler heads in the process buildings were manufactured by Grinnell I

Corporation and installed in the late 1950's and early 1960's. Sprinkler heads have a life expectancy

. of at least 50 years with a code required inspection program after 50 years.

- Cause of Event The direct cause of the sprinkler heads operating at higher than expected pressure was mineral I

deposits on the sprinkler heads due to water leakage and subsequent evaporation. The deposits appear to be salts associated with typical constituents of the sprinkler system water chemistry, e.g.,

calcium, chloride, sodium.

The analysis to determine the root cause ofleakage has not been com%. Preliminary results indicate that the leakage is caused by corrosion ofi %or copper gasket which is designed to provide a seal between the body of the sprinkler head and the sprinkler cap or " button". The analysis to determine the cause of the seal deterioration and the effect of the resulting deposits on the head's l

operability has not been completed. Metallurgical testing of failed sprinkler heads is ongoing at l

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GDP 99-2056 Page 4 of 4 Event Report 99-17, Revision 1 PORTS. PGDP is involved in the investigation and the issue has been discussed with representatives l

of FM and Grinnell Corporation.

In addition to the PORTS and PGDP ongoing testing activities to determine the root cause, PORTS has requested FM to test sprinkler heads that have resulted in HPFW systems being declared inoperable. The purpose of the testing is to determine the pressure required to operate the heads.

The results of this testing will be used to determine if the individual corroded heads were actually inoperable as a result of the mineral buildup. The conservative decision to declare systems inoperable based on the existence of two adjacent corroded heads will then be reassessed to determine the actual impact on HPFW system operability.

Representatives from BETZ Dearbom Water Management Group have been reque-ted by PGDP to assist in determining whether the cause of the deterioration of the copper gasket is due to water chemistry. Water sample analysis will aid in determining the cause and scope of the water chemistry problem. Further water testing will also be done at PORTS.

The results of the sprinkler head testing and water cheroistry testing will be used to determine the root cause and corrective actions necessary to correct the problem. This report will be revised when these actions are complete.

The investigation has also noted that plant personnel did not recognize the potential safety significance of the degraded sprinkler heads when they were discovered and did not promptly initiate repairs. The replacement of the sprinkler heads identified in 1997, as having deposits was given a lower work order priority (priority 6) than those established for routine maintenance (priority 7). The belief that mineral deposits did not make the sprinkler heads inoperable led to the perception that sprinkler hed replacement could be performed as lower priority work. As a result, the sprinkler heads identified between 1997, and August 1999, were not replaced until after the HPFW systems were declared inoperable.

Corrective Actions Corrective actions will be provided following completion of the root cause evaluation.

l Extent of Exposure ofIndividuals to Radiation or Radioactive Materials l

There was no exposure to radiation or radioactive materials due to this event.

Lessons Learned Lessons Learned will be provided following completion of the root cause evaluation.

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