05000278/LER-1979-020-01, /01T-0 on 790621:radioactive Release Rate at Main Stack During Plant Startup Exceeded Tech Specs.Caused by Deficiency in Procedure for Depressurization Following Shutdown.Investigation Underway to Improve Procedure

/01T-0 on 790621:radioactive Release Rate at Main Stack During Plant Startup Exceeded Tech Specs.Caused by Deficiency in Procedure for Depressurization Following Shutdown.Investigation Underway to Improve Procedure

ML19224D554
Person / Time
Site:	Peach Bottom
Issue date:	07/06/1979
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19224D552	List: 05000278/LER-1979-020, Forwards LER 79-020/01T-0 05000278/LER-1979-020-01, /01T-0 on 790621:radioactive Release Rate at Main Stack During Plant Startup Exceeded Tech Specs.Caused by Deficiency in Procedure for Depressurization Following Shutdown.Investigation Underway to Improve Procedure
References
LER-79-020-01T, LER-79-20-1T, NUDOCS 7907120597
Download: ML19224D554 (1)

LER-1979-020, /01T-0 on 790621:radioactive Release Rate at Main Stack During Plant Startup Exceeded Tech Specs.Caused by Deficiency in Procedure for Depressurization Following Shutdown.Investigation Underway to Improve Procedure

Event date:
Report date:
2781979020R01 - NRC Website

text

,

Mr. Boyce H.

Grier Page 2 July 6,

1979 LER 3-79-20/Ir shutdown immediately.

Main stack release, however, continued to increase due to transport time between the vacuum pump and the main stack.

This release continued over approxinately 50 minutes.

The maximum release rate was 106 % of Technical Specification limits.

Technical Specification release limits were exceeded for less than 10 minutes during this transient.

Simultaneoualy with this release, the two reactor building roof vents were releasing at a.value of 11 % of Technical Specification limits.

The maximum site gaseous release rate was therefore approximately 117 % of the Technical Specification limit.

Approximately 1000 Ci of m

,od noble gases were released during this event.

Consequences of Event:

Analysis of the roof vent iodine and particulate samples indicated no significant increase in the iodine or particulate release rates during the period of high gaseous activity releases.

Analysis of the main stack effluent, sampled 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> later when the startup vacuum pump was placed back in service, indicated that the majority of the activity was XE-133 and XE-135 (long lived noble gases).

The release was terminated as soon as the increase in radiation levels on the off-gas stack radiation monitor was observed.

For these reasons, no environmental impact is anticipated.

Plant personnel received no radiation exposure as a result of this event.

Cause of Event

Depressurization of the p rima ry coolant system following reactor shutdcwn introduced non-condensible fission product gases into the condenser.

Transfer of this inventory to the main stack in accordance with normal startup procedures resulted in a gaseous release rate in excess of Technical Specification linits.

The appropriate procedures were deficient in that they did not adequately address the special case of significant fission product inventory in the main condenser with respect to operation of the startup vacuum pump.

Corrective Action

When the increase in the radiation monitor reac ~ ng was noticed, the startup vacuum pump was tripped to terminate the rele se.

Following the initial high release rate, air was pulled through the condenser to provide dilution flow to the vacuum pump during the evacuation of the condenser air space.

This eventually get.dtted establishing a condenser vacuum sufficient to permit return of the unit to service.

No additional releases scc JJ L')

s 79071267

Mr. Boyce 11. Grier Page 3 July 6,

1973 LER 3-79-20/IT in excess of T'chnical Specification limits occurred during the condenser evacuation operation.

An investigation of tnis occurrence is being performed by the Electric Production Department and the Mechanical Engince-ing Division to determine acceptable procedural or equipment modifications to prevent a recurrence.

Yours truly,

/

/ f cf.

Cooney St erintende t Generation Division-Nucle Attachment ec:

Director, NRC - Office cf Inspection and Enforcement Mr. Norman M.

Haller, NRC - Office of Management &

Program Analysis 9

l c r;

>J L'

414G t OHM ;4GL tJ. 5 NUCL L AH 4(L GUL A l Oh ( (.O sti.11: T,luN

/ 71).

, Unit 3 LICENSEE EVENT REPORT Re po r t No. 3-79-20/1T CcNTRotatoco[

l l

g (PLE ASE P9lNT OR TYPE AL L REQUlHED INFORMAilONI 1

6 P l A l' lB lSl3_l@l0l0l-l0 I 0l O l 0l 0 -l0l0 @l4 1l1l1 1l@

l@

0 1

d 9 LICENSEE CODE 14 15 uCENStNUMBEH JS 26 LICE NSE TYPE JG 57 CAT Se ccN T s[RCE d l0 l5 1 01 -l 0l2 l7 18 l@l 0 [ 6 l 2 l 1 1719l@l0l7

.0 8

0 617l9 @

8 60 61 DOCKET NOVBER Gd t9 EVENT QATE 74 5

PEPOR T DATE 80 EVENT DESCRIPTION AND PRC8ABLE CONSEQUENCES h o

2 l

During plant startup, the radioactive release rate at the in stack I

oi3 l exceeded Tech Spec limits followirs; operaticn of the startup vacuum o i4 l

pump.

The release rate exceeded Tech Spec li=its for less than 10 lo s I cinutes. The cannum releaca rate was 106% of Tech Spec limits. The off-

.O 6

l site consecuences of this release were cinical since the majority of I

io i i the activity released was in the fona of mixed noble gases.

I to 8

l 1

7 8 9 80 SYS'E M

CAUSE

CAUSE C O Y P.

V ALV E CODE CCCE SUBCOCE COVPONENT CCDs SUBCCOE SLSCODE I M l31@ L DJ@ l 21@ IP lU lM lP lX lX l@ l H j@ W @

io 9

P S

9 10 11 12 13 16 M

20 SEQUEN TI AL OCCURRENCE REPORT H E VISION O" sg l VENT YE AR LE Rino E

REPOR T NO.

CCUE TYPE NO.

71 91 l-l l01210l l-l 01 1 l lT l l-l l0l a

_. 2 %

22 23 24 26 71 2R 29 30 31 32 AC TION FUTURE EFFECT SHU1DOWN ATT ACHME NT NPRO4 PRIME COMP.

LCVPONENT TAKEN ACTION GN PLANT METHOD HQUR$

44

$UGYITTED FOHM SUL SUPPLI E R MANUFACTURER lX }@l Gl@

C l@

l Z l@

l 010 l0 li l l Yl@

l N l@

l Al@

lNjol1 Ol@

JJ 34 35 3G 31 40 43 42 43 44 47 CAUSE CESCRIPTION AND CORRECTIVE ACTIONS i

o l Reactor depressurization introd2ced fission gas into condenser. This ans j

l i

j was released via main

ack when vacuum pump was started. Vacuum purn I

L was i==ediately tripped. Dilutien air was supplied to reduce release I

j 3 i, }

rate when vacuum pump operation resumed. Engineering invectigation is I

3 l

being conducted to provide cethods or mods to t>revent recurrence.

p

/

8

')

80 F ACit nv ME THCO OF STAYUN

%PGAER QTHER STATUS Ol5COVt HY OiSCOV ERY DESCRIPTION lCl@ l0l0l0l@l N/A l

l A l@l Increasing offgas rad conitor l

Ii 5

r 8

')

in 12 11 44 45 4G 80 ALTIVITY Lt>N T E N T DELEASED OF RELE A$k AMOUNT OF ACTIVITY '-

L0C A TION OF HE LE ASE l G l @ l N}@ 1000 Ci of noble ris l

l Main off-cas stack-elevated releace l

i 6

t 9 3 10 11 44 45 80 Pt AsONNE L F X PO'.UnES NU9uE H l@ TYPE @l DE SCHlP TION -

i l 1010 10 Zl N/A i

H

'J 11 12 13 PE RSONNE L. INJURIES 60 NUVFif G OESCniPTION l>l 101010 l@l N/A 1

4

')

1 12 dQ l C' 5 OF OH O A 4 AGE TO F ACILITY f*PL t )E ',,(, W TIO N L i

{i.

lZj@{

N/A s>'

~)

3 g

.I

~

o "W 'l' I Y p-q f

N hC USE GN LY 1 Y lh[Ot',Ln>P riON r.AEn Jews Rele'ce to Up: and !J for I/.1?fdic,. and Newsingers l! II !I III I I l[

l-o

• 3 to r/ M

/t '/

u

'a eo ;

Nwc m onennen I

(215'i SM-5020 1 J. Cacney P. oN e