ML19340A452

RO 77-107E:on 770907,unplanned Radioactive Gas Release to Turbine Bldg Occurred for 12-h & 40 Minutes.Caused by Gas from Makeup Tank Leaking by Valves MUV-142 & MUV-143 to Bldg Via Vent Valve HYV-25 During Maint on Hydrogen Supply Sys

ML19340A452
Person / Time
Site:	Crystal River
Issue date:	09/15/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19340A448	List: ML19340A447 ML19340A452
References
NUDOCS 8003260791
Download: ML19340A452 (2)

Text

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• UCENSE EVENT

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NAME

• LICENSE NUMBER - TYPE TYPE '

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"@ E74; CATECo. - T oocuT NUMsER EvENr n.TE = oRr o.TE 3 CONT l -l "l .

8 57 58 l0 l5 l0 l-l0-l3 l0 l2 l l0 l9 l0 l7 l 7l 7l 7 l 0 l 9 l1 l5 l7 l 7-59 - 60 61 68 69 74 7 E EVENT DESCRIPTON -

] l In mode 1 operation, an unplanned radioactive gas release to the Turbine Building occurred i' 'S 9

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)gandin.reportedinaccordancewithEnvironmentalTechnicalSpecification5.6.2.A. _

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] l Redundancy N/A. Noble gas was released to the Turbine' Building for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and 40 minutes. .

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. ] ] Unplanned radioactive gas releases have been repetitive but first occurrence as a result J9 E.

~j [ of this cause.

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(LER 77-107E) 39 pnug . E-system , causE coupoNENT COMPONENT 3 CODE CODE - COMPONENT COCE .SUPPUER MANUFACTURER VOLATON l j 'Pl Al y 39 10 ,

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CAUSE DESCRIPTON 0.-

l l l' While performing maintenance on the Eydrogen Supply System, radioactive gas from the

- 19 -

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lf9l Makeup-Tank, leaked by valves MUV-142 and MUV--143 and to the Turbine Building via ve  ;

S; l l valve HYV-25. Vent valve HY.V-25 was closed and personnel instructed not to rely on check I 9, .

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STATUS - 5 POWER OTHER STATUS Dsc0VERY DescovtRY DESCAFTioN l lEl 9 10 l0l9l9l l -NA l @ l High radiation alarm on RMA-12 1 12 13 44 45 46 BC ACT COf4 TENT -

W' RELEASED AMOUNT cF ACTMTV LoCATON oF prira*F i

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OF RELEASE l 185 ' curies noble gasl 10 l Release to Turbine Bldg vent to atmosphere 45 11 ,

44 BC PERSONNEL- EXPOSURES NUMtER TYPE DESCRIPTION 9

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. SC PERSONNEL INJURIES

• NUMC54 ' OESCRIPTON '

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6C OFFSITE - CONSEQUENCES

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f "JSS. OR DAMAGE TO FACIUTY .

TYPE DESCRIPTON .

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ll ADDITIONAL FACTORS l' ~ and sol'onoid valves for boundary isolation

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-l SEE ATTACHED SUPPLEMENTARY INFORMATION *

,m -W. P'. Stewart 1) PHONE: 813/866-4159 c yy ... ......T 1

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l SUPPLEMENTARY INFORMATION -

l Report No.: 50-302 /77-107E Facility: Crystal River Unit #3 Report Date: 15 September 1977 Occurrence Date: 7 September 1977 Identification of Occurrence: ,

. l An unplanned radioactive gas release reported in accordance with Environmental )

. Technical Specification 5.6.2. (A) .

Conditions Prior to Occurrence:

1 Mode 1 power operation in the process of performing maintenance on the Hydrogen '

Supply System. ,

Description of Occurrence: '

At 1605 the condenser vacuum pump exhaust radiation monitor RMA-12 high alarmed. An intensive investigation for a primary to secondary leak began and at 0230 on 8 September 1977 it was determined that instead of a primary to secondary leak, a radioactive gas release was being made to the Turbine Building via the Hydrogen Supply System. Further investigation revealed that maintenance was being performed on the Hydrogen Supply System. The H2 System was found isolated from the Makeup tank by closing Makeup valves MUV-142 and 143 and was vented by opening Hydrogen Valve HYV-25. Noble gas, pri:aarily Xenon 133 from the Makeup Tank was leaking by valves MUV-142 and MUV-143 and into the Turbine Bu'.lding via vent valve HYV-25. After a pe . 'od of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and 40 minutes vent valve HYV-25 wao cloud and the gas release was terminated. A total of 185 curies of noble gas was released. The instantaneous release rate was .32% of the most restrictive limit set forth in Environmental Technical Specification 2.4.2. A(1).

Designat1un of Apparent Cause:

The cause of this event has been determined to be radioactive gas from the Makeup Tank leaking by H 2 check valve MUV-142, H stop valve MUV-143 and into Turbine Building via

. 2 vent valve HYV-25.

balysis of Occurrence:

The health and saf*ety of the plant and general public were not endangered.due to the dilution factor of the Turbine Building ventilation system and the constant release rate

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for the entire period of the release. ,

':orrective Action:

All concerned personnel have been cautioned and instructed not to rely on check or solonoid valves for boundary. isolations. Manual valves will be used in the future for isolation of components if possible. . . .

Failure Data:

Although there have been several unplanned radioactive gas releases,this is the first gas

. release caused by leaking valves.

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