ML19269E011

Forwards Interim Sequence of Operating Events Re TMI-2 Incident,As of 790508

ML19269E011
Person / Time
Site:	Crane
Issue date:	05/16/1979
From:	Jennifer Davis NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:	Gilinsky V, Hendrie J, Kennedy R NRC COMMISSION (OCM)
References
NUDOCS 7906210442
Download: ML19269E011 (49)

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MAY 181979 IE Files /

.Q ent m' "les Reading ROI Reading NC lioseley

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JG Davis LV Gossick

y. w MEMORAHDUM FOR:

Chaiman Hendrie N

Comissioner Gilinsky Comissioner Kennedy g

Comc:issioner Bradford g, c,,

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Coc:nissioner Ahearne FROM:

John G. Davis. Acting Director Office of Inspection and Enforcement

</t h THRU:

Lee V. Gossick, Executive Director fo Ope %rations

SUBJECT:

INTERIM SEQUENCE OF OPERATING EVENTS -

4 -.x.

THREE HILE ISLAND INCIDENT Enclosed is an interim sequence of events developed by the IE investigation team for operating events which occurred at Three Mile Island Unit II on March 28,1979.

Interim is used in the title because the investigation is not yet complete and some of the events and times could change as new infomation becomes available. A finalized version of this sequence will be a part of the final report of the IE investigation which is now expected to be completed by August 1,1979. An interim sequence of radiological and emergency plan implementation events is scheduled for issuance on June 13,1979.

Some highlights from the enclosed sequence will be included in the Commission briefing which is -planned for May 17. 1979. These highlights.will expand on some of the facts contained in the sequence which have not been specifically discussed with the Comission previously.

Evan with the caveat on the possibility of changes, we are releasing the interim sequence at this time to make the information available to the ACRS, NRR and others who are continuing to review the incident for lessons to be learned.

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a THI-2 INTERIH OPERATIONAL SEQUENCE OF EVENTS AS OF MAY 8, 1979 ftAPSED TIME EVENT DESCRIPTION REFERENCES Prior to Turbine Trip Three Mlle Island Unit Two (TMI-2) was operating at 971 power with the Integrated 1.

Interview Control System (ICS) in full automatic. Normal Reactor Coolant System (RCS) 2, GPU Sequence 4/16/79 nakeup and letdown were established with Makeup Pump (MUP) *B" in service.

3.

Chemistry Logs 3/28/79 Pressurizer Spray valve control was in manual-open to equalize Pressurizer and RCS boron concentration. RCS boron concentration was 1026 ppm and radioactivity concentration was S. 397 uc/ml. Identiffed RCS leakage, believed to be from the Electromatic Relief or Code Safety valves on the Pressurizer, was approximately 6 gpm.

Difficulties were being esperienced in transferring an isolated Condensate System 1.

Interview Polisher's spent resins to the Regeneration Recalving Tank. Transfer procedure utilizes Station Afr to fluff resin and Demineralized Water to transfer resin

}

between tanks. A resin block developed in the transf er line.

At this point, plant operators het (wthesized that water pressure may have 1.

Interviews exceeded air pressure forcing wate into the air system. Further the water j

made its way to the Polisher isolation valve controls causing them to drift i

toward the shut position. Since the Polisher outlet is operated within 50 psig of the Net Positive Suction Head limit for the Condensate Booster Puaps, the Condensate Booster Pumps may be the first to trip. (This problen has reportedly occurred before.)

t N

Note: All Polisher inlet a..d outlet isolation valves were found shut af ter the 1.

Interview Turbine Trip.

y Note: Polisher Bypass Valve on THI-2 does not open automatically on high differ-1.

Interview U

ential pressure.

-I sec.

Condensate Booster Pump Trip.

1.

Assumption O

Note: Loss of Suction Pressure will cause a Condensate Booster Pump trip.

1.

Alarm Procedure 17.E9 i

1

e It APSED Tittl EVENT DESCRIPTION REFELENCES

-1 sec.

Condensate Pump 1A Trips (all but one may have tripped). (Actual Time 04:00:36, 1.

Line Printer 3/28/79) 2.

Interviews Note: Paired Condensate Booster Pump trips with the control switch to AUTO will 1.

Alarm Procedure 17.E8 cause Condensate Puraps to trip.

O Main feedwater pumps are tripped resulting in an almost simultaneous trip of the 1.

Line Printer turbine. (Actual time 04:00:37, 3/28/79)

Note: Feedwater Pump suction pressure low or loss of the Condensate Dooster Pumps 1.

Alarm Procedure 17. A15 and will cause the feed Pump Turbines to trip.

Note: Both Feed Pumps tripping will cause the Main Turbine to trip.

1.

Abnormal Procedure 2203-2.2 Note: Tripping both Feedwater Pump Turbines will start the Emergency Feedwater 1.

FSAR Section 7.7.1.2.1.3 Pumps.

Note: Loss of one or more Feedwater Pumps will cause the ICS to runback reactor 1.

FSAR Table 7.7-2 puwer, causing the control rods to be driven into the core, i

I 0+

Energency feedwater pumps start. Pressurizer level and pressure rising rapidly.

1.

Line Printer I

2 Interviews I sec.

Turbine Stop and Intercept valves closed. 500 KV breakers are tripped.

1.

Interview 3 sec.

I's)

Pressure in Reactor Coolant Drain Tank (RCDT) begins to increase.

1.

Reactimeter Data l

N 3-6 sec.

(Jns RCS Reactor Pressure reaches Electromatic Relief Valve (EMOV) opening setpoint 1.

Plant Strip Charts

(,ra (2255psig).

2.

Reactimeter Data 8 sec.

Reactor trips from reactor high pressure (setpoint = 2355 psig). Indicated 1.

Line Printer Reactor pressure on the Wide Range RCS Pressure Strip chart from the control 2.

Plant Strip Charts

-55=

room shows an increase to approximately 2435 psig which suggests one or both 3.

Interviews C:,

safety valves may have lifted. However, this maximum value is not confirmed by the reactineter or by the Narrow Range RCS Pressure recorder trace.

2 w

i __ _ _ _ _ _ _ _. ~... _ _ _..

EtAPSiD Illit EVENT DESCRIPTION REFERENCES 8 sec.

Pressurizer heater groups 1-5 tripped and returned to nornal six seconds later. This 1.

Line Printer event is believed to be related to the operator resetting the pressurizer 2.

Interview spray control to "Autonatic" as an operator action following the turbine trip. A continuous pressurizer spray had been in effect prior to the incident to eliminate a difference in boron concentraticn between the Pressurizer and the rest of the Reactor Coolant System.

9 sec.

Secondary steam pressure peaks at 1070 psig.

1.

Reactineter 2.

Interviews 3.

Plant Strip Charts Note: With ICS in AUTO. Turbine Bypass Valves would attempt to control Main i

Steam pressure at 1010 psig, s 10 sec.

Operator verifies all Control Rods tripped and bottomed.

1.

Interview 6

- 12 sec.

Letdown from reactor secured.

1.

Interviews Note: Operator interviews disclosed that this is an operator action following reactor trips required by procedure to minimize the large anticipated decrease in pressurizer level.

13 sec.

Started Hakeup pump IA. Opened HU-V16B to control MU Pump flow to loop.

1.

Line Printer 2.

Interviews Note: This action, according to interviews, is inmediately taken by the operators ps )

following a reactor trip for the same purpse as the securing of letdown which rs )

occurred at 12 seconds, f.e. minimizing trur large pressurizer level transient which s

C3N follows a reactor trip.

U 13 sec.

RCS pressure reaches setpoint for EH0V closure (2205 psig).

1.

React 1 meter s

L.T1 3

.a--,----.

-w ELAPS [O TIME EVENT DESCRIPTION REFERENCES 14 sec.

Auxiliary Feedwater Punps reach full pressure.

1, Line Printer Note: Auxiliary Feedwater Pump discharge pressure indication is available to 1.

Interview operator on panel, but the only Auxiliary Feedwater flow indication available is 2.

Observation Once Through Steam Generator (OTSG) level changes.

Note: During the transient, the operators reported they did have apparent flow 1.

Interview indication in the "A" S/G from the noise ("hamering") heard from the Vibration and Loose Parts Monitor System which had been turned on to monitor one of the steam generators, s 15 sec.

Pressurizer level reaches peak of approximately 255 inches.

1.

B&W Figures 2.

Reactimeter Data 30 sec.

Reactor pressure low pressure trip setpoint reached (1940 psig), pressurizer 1.

Line Printer i

relief valve exhaust pipe temperature reaches 2390F, and one code safety relief 0

valve exhaust pipe temperature reaches 203 F.

33 sec.

Steam generator "A" level at 23.8 inches.

1.

Line Printer 2.

Interview Emergency Feedwater valves EF-V11AAB start to open as level decreases t>elow 1.

Interview 30 inches and give dual indication on panel.

39 sec.

Make-up pump 1A tripped off. Restarted by operator in 2 seconds.

1.

Line Printer 2.

Interviews N

N Note: During the interviews, the operators noted that they had several problems Ch with keeping mate-up pump 1A cperating when desired. This sequence will note several trips of that pump. The last trip occurs at 4 hrs.18 min. af ter the g

start of the incident, and the pump is not restarted again for the remainder of the incident.

1 40 sec.

A Steam Generator "B" level at 23.7 inches.

Ch 4

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+h-tlAPSID TIMF EVENT DESCRIPT!DN REFERE tKES 54 sec.

Pressurizer level at ministsn of 158 inches (lowest level reached) and starting 1.

B&W Sequence to rise.

2.

Reactimeter 60 sec.

Pressurizer relief valve tall pipe temperatures (safety valve) indicates 1.

Line Printer 294.5 degrees F.

2.

Interviews 1 min.

Steam generators A and B levels very low.

1.

Reactiraeter Dif ferential temperature, Hot to Cold leg, rapidly approaching zero indicating 1.

Reactimeter OTSG's are going dry.

1-4 min.

Pressurizer level rising very rapidly. The rate of pressurizer level increase 1.

B&W Figures during this period exceeds the rate that can be accounted for under the conditions 2.

Interviews of make-up, temperature changes, and injection flow. Moreover, Reactor Coolant 3.

Calculations wide range pressure shows, at 1770 psig (saturation temperature approximately 4.

Plant Strip Charts 619 F) Ion. discontinuity in rate of pressure reduction appearing to indicate void 0

a fonna t This discontinuity, however, is not confirmed by the reactimeter or narrow range pressure instrumentation.

Operating staff interviews covering this period disclose that the operators had felt that they had " caught" the presssurizer level decrease, and that they had actually expected it to drop much further before being " turned around."

Note: It appears that beginning at approximately one * 'qute and continuing there-af ter, one or more steam vapor voids may have ed in the Reactor Coolant System.

s 1 1/2 min.

g Reactor Coolant Drain Tank (RCDT) indicates 86 F (Sign.ficance indeterminate 1.

Line Printer 0

at this time).

s 1 1/? min.

Reactor coolant pressure 1728 psig.

1.

Line Printer U

2 min. 4 sec.

ECCS initiation (HPI - noninal setpoint = 1600 psig). Pressure confirmed by 1.

Line Printer reactor pressure instrumentation. Decay Heat Removal pumps start, and Make-up 2.

Interviews 4

pump 18 trips. Make-up pump IC starts leaving Make-up pumps 1A and 1C row running as HPI with discharge valves full open.

5

4 FIAPSID Tif ti EVENT DESCRIPTION REFERENCES Note: When itPI is initiated, any discharge valves which may have been previously throttled are designed to return automatically to their fully open position. Based on interviews the valves on the 1A pump had not been throttled closed up to this point in the incident.

Steam Generators appear " dry" based on zero lbt to Cold leg RCS temperature 1.

Reactimeter difference.

~ ? 1/7 mln.

Pressurirer level at 207.7 inches.

1.

Line Printer 2.

Reactimeter Shif t foreman enters Control Room and obtains the emergency procedures for 1.

Interview turbine trip, reactor trip, and safeguards actuation to confirm that all dpproprlate aClions occurred.

3t min.

[CCS bypassed by operator actions.

1.

Line Printer 2.

Interviews Control Room Operator throttles MU-V160 in attempt to control Pressurizer level 1.

Interview increase and prevent MU punp runout. By this time MU-V17, the normal Pressurizer level control valve would,be shut since pressurizer level is above control setpoint.

0 s 3 1/? wm.

RCUT tenperature 127 F, tank pressure rapidly increasing and stabilizes at 1.

Line Printer r%s) approximately 120 psig for 3 minutes. The reactimeter plot of RCDT pressure 2.

Reactimeter rs,)

exhibits an oscillatory behavior at 120 psig similar to what would be expected if 3.

FSAR (3ng the RCDT safety valve had actuated. The setpoint for the RCDT safety valve is

===4.

System Description===

listed as 150 psig. The actual safety valve setpoint is not known at this time.

S.

Interviews

(,,4 The operators did not indicate during interviews that the RCDT cooling system (a manually initiated system) was started by them during the transient.

4 inin. 3fi sec.

-Ah-Make-up pump 1C tripped. Make-up pump 1A still running in throttled condition.

1.

Line Printer CJC) 2.

Interviews 6

~

It /Milj _Ilpt.

EVENT DESCRIPTION REFERENCES Note: During this period attempts were underway to reestablish normal condensate 1.

Interviews system. Based on interviews, it appears that when the flow from a Make-up 2.

Line Printer pump operating in the High Pressure injection mode is throttled, the operators do not reduce flow below approximately 100 gpm in order to protect the punp.

This minimum flow is acconplished only by shutting the valve in one of the two injection paths. If both paths are open, the flow is 200 gpm. There fore, minimum pump flow, when the pump is operating, appears to be at least 100 gpm.

by 54 min.

Operator initiates letdown at rate in excess of 140 gpm in attempt to halt Pressur-1.

Line Printer izer level rise. Orifice and bypass utilized together.

2.

Interview Note: At five minutes after the transient, pressurizer level starts dropping at a 1.

B&W Figures rate of approximately 60 inches per minute for 15 seconds. At this sane 2.

Line Printer time, an apparent decrease in loop "A" flow and increasing reactor coolant 3.

Interviews tenperatures are observed. Upon receiving a high ietdown temperature (at

• 7 min) the operator throttled letdown to

• 70 gpm. The pressurizer level rate of change is not in agreement with the actions, system temperature changes, arui make-up pump operation occurring during this period.

6 min.

Pressurizer bubble lost. RCOT pressure starts rapid use above 120 psig to the 1.

Reactimeter RCDT Safety Valve setpoint of approximately 150 psig, possibly the result of 2.

Plant Charts passing liquid versus steam. RCS pressure now tracks Hot leg saturation pressure.

3.

Interviews Combination of full Pressurizer indication and increasing RCS pressure, the result y

of rising hot leg temperature while charging with the one MU Pump, convinces operators they have a solid plant.

/ min. 4 3 sec.

Reactor Building sump pump (WDL-P-2A) turns on, presumably pumping 140 gpm from the 1.

Line Printer u

Reactor Building Sump to the miscellaneous waste holdup tank (WDL-T-2) via the 2.

Interview norwilly open Reactor Building isolation valves. However, tank level records show this tank to have not changed level during the incident, and there is reason to believe the sump pump discharge was aligned to the auxillary building sump tank. (This tank had a blown rupture disc which was scheduled for later repair.) These isolation W

valves do not close on the SFAS signal which initiates itPl. These close only when 4 psig in the Reactor Building SFAS setpoint is reached.

7

2--

+

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{tA11tD.IIpt EVENT DESCRIPTION REFERENCES 8 min.

Operator finds 01SG level at 10 inches on the Startup Range. Operator considers 1.

Interviews this level means OTSG is " dry" per his training. Operator verifles Energency 2.

Reactimeter feedwater Pumps are running and examines valve lineup. Operator finds and 3.

Plant Strip Charts announced that EF-V12A & 128 are shut. Position indicating lights on 128 were 4.

Surveillance Test Procedure obscured by a caution tag hanging from another valve controller. Position indicting lights for 12A may have been obscured by operator's body as he leaned over panel.

Operator drives valves open, resulting in dry OTSG being fed with relatively cool water. Hot and cold leg temperatures drop. RCS pressure, now under control of loop sa tura tioti conditions. follows accordingly.

A routine, scheduled surveillance test was performed on the A & B electric energency feedwater pumps on March 26, 1979 at approximately 10:00 a.m.

Implementation of this survelliance test procedure results in closure of both the 12A and 128 valves, regardless of which pump is being tested. The procedure calls for reupening of the valves, along with insuring the proper status of at least three other valves, lhe procedure for the electric driven emergency feedwater pumps is insuffic-lently specific to provide documentation of valve opening in that the procedure does not require individual signoffs for each valve rather, the procedural requirement is in sentence for1a with one signoff signifying proper positioning of the valves.

The investigation thus far has not found any evidence of willful closure of the valves ove.- the period of 3/26/79 to 3/28/79.

(On 3/23/19, an NRR Operator Licensing Branch (0LB) Examiner conducted exams and 1.

OLB exam records

" walked thru" the EfW System. The valves were open on that day.)

Be min.

Rapid rise in OlSG pressure observed indicating feed flow to generators. Confirmed 1.

B&W Figures by EfW pump discharge pressure decreasing and "hamering" and " crackling" heard 2.

Interviews from the Vibration and Loose Parts Monitor Speaker aligned to listen to "A" 01SG.

N Radiation Monitors in letdown system show decreasing level.

N 8 1/2 min.

Hot leg tem >erature dropping rapidly at a rate of approximately 110"F/hr.

1.

Reactimeter 10 min. 19 sec. U Second Reactor Building Sump pump (WDL-P-20) starts. Now pumping Reactor Building 1.

Line Printer Sump to the Auxiliary Building at 280 gpm.

Note: Second Reactor Building Sump pump starts based on rising level in sump.

10 min. 24 sec. O Make-up pump 1A trips, and restarted within 3 seconds. Trips again in I second.

1.

Line Printer 10 min. 48 sec.

Reactor Building high sump alann (setpoint 4.65 f t).

1.

Line Printer Note: The Control Room Operator reported that the sump overflowed (6 feet) some-1.

Interview tiae af ter this point.

8

+

3 LIAPSID 1.lfK EVENT DESCRIPTION REFERENCES 10 to 11 min.

Pressurizer level canes back on scale and drops rapidly, as RCS loop tanperatures 1.

Reactimeter continue to drop frun heat removed by the OTSGs and the EF pumps. Apparently, the operable Pressurizer lleaters and the llot Leg water, received fran the surge line, liave lieen able to raise saturation conditions to the point where a bubble is again reestablished in the Pressurizer at approximately 1475 psig.

Il 1/2 min.

Intermediate cooling for RCDT cooler indicates offscale.

1.

Line Printer 11 min. 40 sec.

Make-up pump 1A restarted, trips, and restarted.

1.

Line Printer Punp 1A renuins af ter this restart in throttled condition until second IIPI initiation at 3 hrs. 23 min.16 seconds.

8 to l? min.

Operators attenpting to establish 30 inches in each steam generator per t rocedure.

1.

Interviews 13 min.

Decay lleat (Dil) pump 1 A and IB off.

1.

Line Printer 15 min.

RCS pressure approxinately 1275 psi 0 with cold leg temperature of approximately 1.

Reactimeter 5670f. Saturation pressure for 567 F is 1185 psig.

2.

Plant Strip Charts 15 min.

RCDT rupture disc blows at a RCDT indicated pressure of 192 psig, dropping RCDT 1.

D&W figures pressure to approxinately 10 psig in 36 seconds. Pressure rise seen in Reactor 2.

D&W Sequence Dullding.

3.

React 1 meter N

16 to 1/ min.

Reactor Coolant Pump related alanns received including full speed alarms. (During 1.

Line Printer N

entire transient there was a slow reduction in indicated loop flows. These types 2.

01W figures of alanns were also received at various periods af ter this point until the pumrs 3.

Interviews U

were shut down.)

Started Condensate Pump CO-P-1 A.

1. L!ne Printer 18 min.

ruel handling exhaust monitors show small rann increase in Iodine reading.

1.

Plant Strip Charts Reactor Building Exhaust shows factor of 10 increase in reading.

9 s

^

1 Il AySt lLil!L EVENT DESCRIPTION REFERENCES Note: RCS was effectively being degassed into the Reactor Coolant Drain Tank and, 1.

System Descriptions when rupture disc blew, gas was released into the Reactor Building.

RCDT vent lines isolated at 10 psig automatically but af ter the rupture disc blew, the vent line valve reopens (6 psig) and opened the RCDT to the waste gas system. The waste gas system header is maintained at 2 psig and as long as the Reactor Building isolation had not occurred, the waste gas compressors pumped gas from the Reactor Building to the gas surge tank.

20 to 40 min.

Steam driven auxiliary feedwater pump turned off. Operator trying to establish low 1.

Line Printer level limit in steam generators; he closes EFV-118 and then EFV-128, and shuts down 2.

Interviews pump. (Later shuts down electric pump. Steam generator pressure being controlled 3.

Plant Strip Charts manually through turbine bypass valves.) Operator observes condenser hotwell level high and starts condensate pump. Finds suction pressure low when starting conden-sate booster pump and it trips. Bypassing condensate polisher is unsuccessful from control room, and " bad leak" is found on suction side of 2A booster pump. All polisher inlet and outlet valves found shut, and bypass valves had to be manually opened. This pennitted establishing reject flow and returning hotwell level to normal. This is part of line-up efforts to pennit restart of main F.W. pumps.

Note: Hotwell was flooded due to level controller failure; probably the result of 1.

Interview the initial transient.

20 min.

Increase seen on nuclear instrumentation and reactor manual trip perfonned.

1.

Line Printer Radiation level on letdown monitor increases and returns to previous level.

2.

Plant Strip Charts N

Note: from approximately 20 to 60 minutes, system parameters generally stabilized 1.

Plant Strip Charts N

at a reactor pressure 1015 psig, reactor coolant average temperature of 5500F, 2.

B&W Sequence ON and a pressurizer level of 380-395 inches.

3.

Reactimeter 32 1/2 min.

Incore thermocouple (location 10-R) indicates offscale.

1.

Line Printer 36 min.

EFW Pump "B" turned off.

1.

Line Printer N

10

~

-- 2 -- ~~-

-. ~ - -

tlAPSED TIMF EVENT DISCRIPi!ON REFERENCES 3H min.

Reactor Building Sump pumps turned off by Auxiliary Operator. The two sump 1.

Line Printer pumps had operated for 31 and 28 minutes, respectively, pumping approximately 8260 gallons of water to the Aux 111ary Building. Shutdown of the pumps does not result in isolation of the pump discharge line. The possibility of continued water transport to the Auxiliary Building caused by elevated containment pressure and considering tank elevations in the Auxiliary Building is yet to be analyzed.

45-50 min.

Steam generator "A" level starts trending down while generator "B" level starts 1.

B&W Sequence trending upward.

2.

B&W Curves Superintendent of Technical Support, the on-call Duty Officer, reports to the site.

1.

Interviews (0 min.

Circulating water pumps B, C, D, E off. Letdown line radiation monitor shows 1.

Line Printer small ircrease in level.

Plote: The circulating water pumps were turned off to automatically switch steam dump to the atmospheric relief valves to prevent flooding of the condenser.

flote: The intermediate cooling water radiation monitors (1082 and 1083) alarm due to high background near containment sump which was being overflowed from the Reactor Coolant Drain Tank rupture disc.

N

• 1 hr.

y On call Operating Engineer called to come to site.

1.

Interview 71 min.

D Reactor Building air cooling coil B indicates "on".

The Reactor Building cooling 1.

Line Printer U

was initiated with emergency river water cooling through the Reactor Building 2.

Interview cooler.

73 min.

Alarm printer unavailable starting at this time. Not returned to service untti 1.

Interview u

2 hr. 47 min. Operator interviews indicate that there was a malfunction of the 2.

GPU Sequence 4/16/79 paper feed. Exact nature of this problem not established at this time, although 3.

Records Reviews review of other alarm printer output for various other periods shows evidence of paper feed problems.

11

A.

fl ApSIll TIMf_

EVENT DESCRIPTION REFtRENCES Prior to 74 min.

Reactor coolant loop flow indication has been steadily decreasing and indicated 1.

B&W Figure flow in loop B at 74 min. approximately 60% of normal value. Operators report 2.

Interviews receiving vibration alarms 6..

. reactor coolant pumps (RCP). Chart recorders 3.

Plant Strip Charts for source range nuclear instrumentation show increasing counts with increasing amplitude of oscillation.

Operators reportedly recognized that they were violating 4 RCP pressure-temperature 1.

Interview l

limits and the pin compression curves.

71 min.

RCP's in B loop chosen to be tripped to be able to maintain maximum pressurizer 1.

Interviews spray capability which comes from A loop. RCP 18 and 2B tripped. (Line Printer 2.

P&lD Indicates that RCP 2A also tripped. This inconsistency will be reviewed further.)

3.

Line Printer 4.

B&W Figure 5.

B&W Sequence 74 min.

Operators reported flow oscillations decreased immediately following pump trip.

1.

Interviews Moreover, Source Range (SRM) instrumentation count rate oscillatory behavior 2.

Plar." strip Charts significantly decreased. SRM count rate was approximately three times the value 3.

B&W Sequence that would be expected at this time af ter reactor trip. RCS pressure indicates 4.

B&W Figures an upward pressure trend, and "B" steam generator pressure drops fnmn approximately 960 psig to 140 psig over the next 18 minutes.

75 min.

RCS sample yields 700 ppm Boron. Sample required within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of trip. Results 1.

Interview questioned by technician and started to get additional sample.

80 min.

rs;)

Factor of 10 increase in radiation level as shown on letdown line penitor.

1.

Plant Strip Charts N

81 min.

Surge line temperature 513.90F.

1.

Line Printer CJN 87 min.

E 'd The "B" steam generator was isolated at this point (87 min.). Operators had ob-1.

Control Room Logs served increases in Reactor Building pressure and noted that pressure in generator "B" was 300 psig lower than "A" and believed steam was leaking into the Reactor

---a

(_y1 Building. Af ter isolation of steam generator "B", they note building pressure

,g3, leveling off and "B" generator level is trending upward so they secure the third EFW valve to the generator. EFV-SB.

12

I IL&PSED Tif1E EVENT DESCRIPTION REFERENCES Note: Reverse flow should have occurred in the B loop as a result of continued operation of the pumps in the A loop. No substantial changes in steam generator level or pressure occurred over the next hour. It appears that reverse flow of RCS coolant at a temperature of approximately 5500F was not occurring through the "B" generator.

• 90 min.

High Radiation readings in llot Machine Shop.

1.

Interview s 90 min.

RCS Sample yields 400-500 ppm Boron and 4.0 uc/ml; a further drop in Boron and 1.

Interview a factor of 10 increase in activity.

Prior to 100 min.

Approximately 5-10 minutes after the trip of the B loop RCP's SRM count rate 1.

Plant Strip Charts instability increases again as well as continuing an upward trend. Operators 2.

Interviews report loop flow instability increasing again, and the indicated loop flow con-tlnues to show a decrease. Operators state they were concerned about a " seal failure LOCA" and decide to go on natural circulation. Operator stated that he started "eriergency boration" during this period.

100 min.

"A" loop RCP's tripped. SRM count rate spikes upward to peak at least one decade 1.

B&W Sequence over count rate expected following a normal reactor trip. All radiation monitors 2.

D&W Figures exhibiting substantial ramp increase.

3.

Plant Strip Charts Operators stated they did not believe that natural circulation had been established 1.

Interviews due to the differential temperature across the steam generator and the low steam l

g generator pressure.

N Note: RCS was at 1020 psig and 5350F; well outside prerequisite pressure / temperature O

conditions for establishing natural circulation.

U 1006 min.

Operators report increasing HPI flow. RCS Pressure shows increase. SRM 1.

Interviews counts drop significantly.

2.

Plant Strip Charts LT1 Ln 13 w

em=

p

.2...

~..

(1 APSED JIME EVENT DESCRIPTION RE FERENCES 100t min.

Per procedure, operator begins feeding "A" steam generator to reach 501 level.

1.

Interviews tevel in "B" steam generator also appears to increase, but trailing "A" steam 2.

Plant Strip Charts generator level. Operator states he is still controlling steam generator 3.

B&W Figures pressure manually with turbine bypass valves.

The SRM count rate level, followed by Intermediate Range Monitor (IRM) output, start upward increase. Over the next 15 minutes. SRM count rate level increases 2 decades without exhibiting previously observed oscillatory behavior. Operator reports he " emergency borated" again.

1 1/2+ hrs.

RCS Hot and Cold leg tempratures begin to diverge widely. Hot leg tamperature 1.

B&W Figures begins to rise to 620 degrees F (of f scale within 14 minutes) and cold leg 2.

Plant Strip Charts tenversture drops to 150 degrees F (apparently from ef fect of HPI water). The 0

operators reported average RCS temperature " stabilized" (570 F).

Note: It appears that the average RCS temperature (Tav) recorder trace could no longer be relied upon by the operators for the period from 21/2 tours to 0

10 1/2 hours. Tav stabilized at an indication of 570 F as soon as the narrow range T hot and T cold instruments reached their display limits.

s 2 hrs.

Nuclear Engineer called to site to gather infonnation required for standard post-1.

Interviews trip report. Some question at that time whether a restart had occurred based on SRMs.

~ 2 hrs.+

Conference call established between Unit 2 Technical Supt. (Unit 2 Control Room) 1.

Interview and Station Superintendent Vice President of Generation and IIAW site repre-sentative (at their homes) lasting approximately 30 minutes. l(new trip was N

abnormal since RCPs were off and unable to draw Pressurizer bubble. Blown rupture N

disc and water on floor were not surprising since this had happened before. The condition of the EMOV block valve was questioned and reported to be shut. (It should be noted that the position indication on this valve is a " demand" position U

rather than actual valve position.) Group decided need existed to restart an RCP and all should report to IMI. (Conference call had been initiated by Station i

Supt. follnwing call from Unit 2 Tech. Supt. (on-call Duty Officer) around I hour m

40 minutes into event.)

Ch 14

i Et APSED TlHE EVENT DESrRIPTION REFERENCES (B&W Representative reports that the fact that EFV-12A & B were shut with no 1.

Interview feeding to the S/Gs for 8 minutes was not discussed the first day. It was discovered by B&W representatives later while delogging the reactimeter.)

2.3 hrs.

Electromatic relief valve isolated by operator by closing the block valve (RC-V2) 1.

B&W Sequence Operators had noted tall pipe temperature on relief valve 35 F higher than others 2.

Interviews and believed valve to be leaking. Noted a drop in Reactor Building pressure after closure of the block valve.

The pressure change in the Reactor Building was more marked than when "B" S/G 1.

Interview was isolated. The plant operations group decided that the "B" S/G probably did not have a leak from the shell into the Reactor Building. The "B" S/G still had a level.

i 2.3t hrs.

With closure of EMOV. RCS pressure begins increase from low point of 660 psig and 1.

B&W Figures reaches 1300 psig. During this period (up to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />), no change in pressurtzer 2.

Plant Strip Charts level is observed.

Prior to this point, standard post-reactor-trip Boron sanples taken from the 1.

Interview Reactor Coolant System had been analyzed with no problems indicated or oetected relative to radiation levels.

Fifteen to twenty people in Control Room at this time.

1.

Interview s 2 hrs.-2.5 hrs.

Area Radiation Monitor (ARM) alarms at sample station. Letdown sample lineup 1.

Interview secured.

ps y r% )

2 hrs. 18 min.

Radiation monitor on Letdown I!ne experiences a further increase of a factor 1.

Plant Strip Charts (CF5 of 100.

1'

(.mJ 2 hrs. 45 min.

Make-up pump IC tripped by operator action according to GPU sequence. Ilowever, l.

GPU Sequence the GPU sequence does not indicate a start time. The last identified change of 2.

Line Printer status was at 4 min. 38 sec. when the ump was tripped. No other status change g_7) is noted up to I hr.13 min. 27 sec. w en the line printer stopped working.

15

+ - _ _ _ _ _ -. _.. _ _ _ _

Et APSt u llME EVENT DESCRIPTION REFERENCES Opened "B" OTSG Main Steam Valve (HS-V4B & V78).

1.

Line Printer 2 hrs. 47 min.

Alarm Printer returned to service following clearing of paper feed problem.

1.

GPU Sequence 4/16/19 2.

Line Printer s 2 hrs. 50 min.

Site Emergency announced.

1.

Interview 2 hrs. 50 min.*

North Bridge Gates being closed due to Guards responding to establishment of 1.

Interview Site Energency.

t brs. 54 min.

Operators start RCP 2B and it runs for 19 min. Operators state they received all 1.

Line Printer radiation alarms. Operators started RCP because they were not sure that natural 2.

Interviews circulation had been established. During this operation of the pump, Rr5 3.

Plant Strip Charts pressure went up to 2200 psig.

Groups 1-5 of the pressurizer heaters trip and remain in a tripped state for 1.

Line Printer 1 1/2 hours. Throughout the course of the incident, difficulty is experienced 2.

Interview with multiple piessurizer heater trips, presumably due to noisture content in the t eactor containment, a problan previously experienced on Unit 1 at this site and other facilities. As of this time, no more than eight groups of heaters are operable.

~ 2 hr. 55 min.

HP Technician reports over page that letdowa sample lines from Unit 2 was reading 1.

Interview 800 R.

Unit 2 then declared a site emergency.

FN )

s 2 hrs. 56 min.

Isolated "B" OTSG by closing MSIVs (HS-V4B & V78). (Operators isolated OTSG 1.

Line Printer ps )

based on alarm from condenser offgas monitor.) Pressure climbed rapidly in "B" 2.

Reactimeter C rs 0158 during RCP operation.

U Secured liquid release from Unit I and Unit 2 Operators verified valves closed.

1.

Interviews CJO i

16 i

It APSID TIMF EVENT DESCRIPT!0N REFERENCES

• 2 hrs. 57 min.

Radiation level in vicinity of Unit 2 sample area, where lines were on recircu-1.

Interview lation for another Boron sample, reportedly showed marked increase, fifty to sixty people estimated to be in Control Room at this time with noise

1. Interview level very high.

Prior to 3 hrs.

Pressurizer level starts increasing at this point and rate of RCS pressure 1.

B&W Figures increase becones more rapid and reaches 2100 psig. Pressurizer reaches level of 2.

Plant Strip Charts 380 inches. At approxinately 2 hrs. 49 min. the IRM Indication returned to zero.

3 hrs.*

Eighteen to twenty-four people in Control Room at this time. (Not known at 1.

Interview this time if excess staff left control room or if variance is due to operators estinu tes. )

Trying to recover Pressurizer Level indication which was now off-scale high.

1.

Interview 3 hrs.'

Guards at North Gate delay, then allow B&W site representative access to site.

1.

Interview Guards were sending others to observation center.

3 hrs. 4 min.

OTSG "A" Pressure Control shif ted from Turbine Bypass Valves (MS-V25A & B) to 1.

Line Printer Power Operated Energency Main Steam Valves (MS-V3A & B).

N 3 hrs. Il min.

EFW pump (EF-P-2A) tripped by the operator. At this point, steam generator levels 1.

Line Printer I)

were in the 55% to 65% range.

2.

B&W rigures

(_p4

~ hrs.13 min.

RCP 2B tripped by operators af ter vibration alarms received and gtor only 1.

Line Printer drawing 100 amps. Operator notes no change in Tave; still at 580 F.

4 17

E l AP51 D T IME EVENT DESCRIPTION REFERENCES 3 hrs. Il min.

Operator opens EMOV (RC-RV2). Nigh temperature noted on tall pipe of relief 1.

Line Printer valve. Not possible to ascertain at this point if Block Valve had been previously 2.

B&W Sequence opened and if EMOV was operating in automatic mode. RCS pressure and pressurizer 3.

B&W Figure leval both drop (RCS pressure to 1975 psig; pressurizer level - 300") and Reactor 4.

Plant Strip Charts Building pressure increases. A pressure spike of 5.5 psig also seen in RCDT.

3 hrs. 13 min.

Operator stated that coincident with tripping of RCP further radiation alarms 1.

Interviews received and they started following radiological emergency procedures.

2.

Plant Strip Charts Note: At about 3 hrs.. the line printer displayed incore thermocouple data accumulated earlier (approx. 2 hrs. 55 min.):

Thermocouple location Temperature (oF) l TC 12-0 623 1C 14-M 653 TC 14-D 687 TC 13-C 577 TC 11-L 584 TC 10-C 599 N

TC 2-G 623 N

Moreover, a large number of entries were made for the incore monitoring u

system. Entries appear erratic in nature.

3 hrs. 13 min.t Date accunulated at 3 hrs. show:

O Thermocouple tocation Temperature OF CD TC-13G 675.6 TC-3F 694.1 TC-SD 666.1 18

ElAP51D Tpif EVENT DESCRIPTION REffRENCES 3 1/4 hrs.

Control Building evacuated.

1.

Operating togs 2.

Ir.terview 3 1/4 firs.

Af ter RCS pressure holds at 1975 psig for approximately 5 minutes, a rapid 1.

Operating Logs pressure decrease begins and RCS pressure reaches 1500 psig. Pressurizer level 2.

B&W Figures dropped during this period to 225 inches. A RCDT pressure spike of 11 psig is 3.

B&W Sequence seen at this time and Reactor Building pressure increases from 1 to 3 psig.

4.

Plant Strip Charts 3 hrs. 20 min. 13 sec.

Make-up pump IC started. Reason for starting unknown at this time.

1.

Lint Printer Note: Make-up pump 18 tas been off since llPI initiation at 7 minutes af ter the start of the incident.

3 hrs. 23 min. 16 sec.

IIPI initiated (set point = 1600 psig); RCS pressure and pressurizer level increase.

1.

Line Printer Hake-up pumps I A and 1C should be operating with discharge valves fully open.

2.

B&W Figures Operator interviews covering prior period do not indicate that pump 1A had been 3.

Interviews turned off.

3 hrs. 26 min.

Reset flPl. Pressurizer level of 254" indicated. EFW pump 2A is started.

1.

Line Printer 3 hrs. 30 min.

General Emergency declared (IRACT tape information indicates beneral Emergency 1.

PN declared at 3 hrs. 24 min.)

+ 3 hrs. 30 min.

B&W site representative arrives in Unit 2 Control Roan. Station Superintendent 1.

Interview ps )

was in Control Room. Operators reported they had run a RCP as directed with 100 amp indication. Operators report that "many" Pressurtzer lleaters are "out of FNs) canmission "

CD L.r4 i

j I

CJrs 19

L_

4 i

EtAPSID 11ML EVENT DESCRIPTION REFERFNCES 3 hrs. 32 min.

Make-up tank radiation level 3 R/hr and Auxiliary Building Basement reported 1.

Operating Logs as flooded with airborne activity. Spent fuel demineralizer area monitor reading 2.

Line Pririter 250-900 mr/hr. SRM count rate found to have increased by about a factor of 3.

3.

Plant Strip Charts

( Abnve radiation level readings from hallway of elevation 305', Auxiliary Building) 4.

Interview (Basement referred to above is elevation 281'; Auxiliary Building)

)

3 hr s. 35 min.

[FP 2A is running.

3 hrs. 37 min.

Make-up Pump IC is tripped. Pump 1 A is still in operation.

1.

Line Printer 3 hrs. 42 min.

Reactor Building air sample line isolated after being reported as blowing air 1.

Line Printer into another area.

2.

Operating Logs 3 brs. 48 min.

Reactor Building high range and fuel handling bridge monitors less than 1 mr/hr.

1.

Operating Logs 3 hrs. 55 min.

Reported less than 1 mr/hr North Gate; Rt. 441 less than 1 mr/hr.

1.

Operating Logs Station Superintendent directed outside Agencies be contacted to report incident.

1.

Interview 3 hrs. 56 min.

Make-up pump IC started.

1.

GPU Sequence

% 4 hrs.

By this tine, pressurizer level is restored to approximately 380 inches with a 1.

B&W Figures reactor pressure of 1500 psig.

I Detector shielded with 4 inches of lead located in containment dome reading 1.

R-1 of RI Incident 200 R/hr.

Messageform ps )

I'd Station Supt. requests B&W site representatives and others caucus with him in CJh' Shif t Supervisor's office. Decided to try another RCP start since pressure

(_e4 was high enough.

f Note: Philoscphy of discussions reported to consider current situation and options available for return to normal conditions; not retrospective to determine t

C]"'

how arrived in this condition.

N s

20

..L_..

e E l ff 5E D_l [Mt EVENT DESCRIPTION REFERENCES 4 hrs. 8 min.

Unsuccessful attempts were made to start RCP-1A during this period. It appears 1.

Line Printer that several ef forts at clearing the building isolation signals were nade to support equipment operation.

Note. Had problems getting a RCP started. Believe problems associated with RCP 1.

Interview lif t pump inoperability. Finally got RCP started in one loop and then the other. Motor amperage in each case convinced group that there was steam in the loops.

4 hrs. 14 min. 40 sec.

One of the three SFAS channels monitoring Reactor Building pressure actuate 1.

Line Printer (nominal setpoint = 4 psig).

4 hrs. 17 min. 17 sec.

Make-up pump 1A tripped.

1.

Line Printer 4 hrs. Il min. 22 sec.

Make-up pump IC tripped.

1.

Line Printer Note: Based on interviews. It appears that the operators were monitoring the rise 1.

Interviews in building pressure following the actuation of one channel of SFAS, and 2.

Reactimeter they placed the make-up pump selector switches in the " pull to lock" position.

This action apparently was taken to prevent HPI during a time when the pressur-f rer appeared to te " solid".

I 4 hrs, 17 min. 30 sec.

Second SFAS ctannel actuates on high building pressure (4 psig). It appears that 1.

Line Printer only the "A" logic actuated. The line printer shows that the channel "A" Groups 1, 2 and 3 building isolation logic actuated. Decay heat removal pump 1A starts.

l (This pump appears to run for approx. 60 minutes untt15 hrs.19 min.) This high I's) pressure actuation appears to have cleared in approximately 18 seconds and is I5 )

reset by operator action.

s ON

(,eJ At approximately this time, the SRM count rate increases s11ghtly and then continues 1.

Plant Strip Charts to decrease.

N 3

U 21

s -- - -.. - -..... -. - ~...

LtAPSID 11PL EVENT DESCRIPTION REFERENCES 4 he s. 20 min.

Containment Dome Radiation monitor reads 600 R/hr.

1.

Operating Logs 2.

RI-R-01 4 hr s.18 1/2 min.

Operators start Make-up pump 1A but the pump trips off in 3 sec. This pump 1.

Line Printer remained off for the remainder of the period covered by this sequence 2.

Interviews Nute: from 4 hrs.17 min. 22 sec. until 4 hrs. 21 min. 53 sec., no make-up pumps were operating, a period of approximately 41/2 minutes.

4 hrs. 22 min.

With the unsuccessful attempt to start make-up pump 1 A, the operators start pump 1.

Line Printer 13.

This pump remains in operation for the remainder of the period covered by 2.

Interviews this sequence.

4 hrs. 24 min.

Pressurizer heater groups 1-5 are returned to normal. All pressurizer heaters 1.

Line Printer are operakle at this time.

4 hrs. 26 min.

Letdown high temperature alarms received.

1.

Line Printer 4 hrs. 21 min.

Attempt to start Make-up pump IC initially unsuccessful but started within 1.

Line Printer approximately 3 seconds. This pump remains in operation untti 3 hrs., 4 min, after the start of the incident.

FN ) 4 hrs. 31 min.

Group 10 of the pressurizer heaters trips. This group does not become operational 1.

Line Printer s

rs )

again during the period covered by this sequence.

I s

CJrs I

4 hrs. 40 min.

Containment Dome Radiation Honitor reads 1000 R/hr.

1.

Rl-R-01 (smJ 4 his. 42 min.

EFW Pump 2A turned off. Steam Generator levels appear stable in desired range.

1.

Line Printer

--~*

2.

B&W Figures C3%

.g==

4 hrs. 46 min.

Groups 4 and 5 of the pressurizer heaters trip and do not become operational for I.

Line Printer the remainder of the period covered by this sequence. No more than 10 heater groups are now operational.

22

It AP5t u IIMI EVENT DESCRIPTION REFERENCES 4 hrs. 59 min.

IIP! flow is 250 gpn/ leg - RCS pressure 1400 psig 1.

Region I Incident Messagefona 5 hrs.

General parameters at this points:

1.

B&W Figures 1.

RCS pressure 1375 psig and generally stable; 2.

Reactor Building pressure approx. 4 psig and stable; 3.

Pressurlier full; 4.

Steam generator levels40-501 and steady; 5.

Steam generator pressures "B" decreasing slowing from 325 psig and "A" at 50 psig and increasing.

5 hrs.

Containment Dome Radiation Monitor reaches 6000 R/hr.

1.

RI Incident Messageform

~5 hrs.

Licensee reported to Region I at 0900 (elapsed time = 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) that the Aux. Bldg 1.

RI Incident Messagefonn.

was isolated at 0800. Reported that "B" Steam Generator leak was noted at 0800 by Vacuum Pump Monitor.

5 hrs. 10 min.

Region i Inspector at site reports to Region I that based on his discussions.

1.

RI Incident Messagefono some staff members believed code safeties may not be closed. SG Levels A-44%.

B-66%; said S/G's isolated.

5 hrs. 15 min.

Based on first infonnation recorded on Region I Incident Response Center (IRC) 1.

Region ! IRC Tapes Tapes.

N 1.

MSL Safety Valves said to be shut.

N 2.

S/G "A" Level reported at 44%.

3.

S/G "B" Level reported at 66%.

4.

S/G are reported to be isolated.

~

CP t J1 5.

RB Spray had not actuated yet.

~5 hrs 15 mins.

Convinced steam in each loop, decided to raise pressure and collapse unwanted 1.

Interview steain bubbles. Verified again EMOV block valve was shut. (Recall position

" indication" shows valve position demand rather than actual location.) Increase in liigh Pressure Injection flow is directed.

23

IIAPMD Tirtf EVENT DESCRIPTION REFERENCES s5 hrs. 15 min. (Continued)

Concerned if RCS pressure went too high, it could cause code safeties to be opened. Decided to control pressure at 2000-2100 psig using EHOV and its block valve.

5 hr s. Il min.

Reactor Building Air Cooler B started.

1.

Line Printer.

5 his. 18 min.

Block valve c.n EHOV opened. (When this valve was previously closed is not known 1.

B&W sequence at this tinee.) Building pressure starting to decay and RCS pressure rising.

5 hes. 19 min.

Decay heat pump 1A turned off.

1.

Line Printer 5 hrs. 21 min.

ESF Actuation in Red and Blue Channels due to 4 pst in Reactor Building cleared.

1.

Line Printer 5 hes. 25 min.

ESF Actuation in Yellow Channel due to 4 psi in Reactor Bu11 ding cleared.

1.

Line Printer 5 hrs. 30 min.

ESF Actuation in Green Channel due to 4 pst in Reactor Building cleared.

l.

Line Printer 5 hrs. 31 min.

Group 3 of the pressurizer heaters trips and remains inoperable for the re-1.

Line Printer mainder of the period covered by this sequence. No more than 9 heater groups are now operational, 5-6 hrs.

flote:

1. Reactor Bu11 ding pressure showed a peak of 4.4 psig and trended down-1.

Plant Strip Charts ps )

ward to 1.6 psig during this period. SRH count rate showed a general I)

decrease with no anomalies. Steam Generator "A" level raised to 951 CDrs from 50%. (Reached at approximately 6 hrs. 20 mins.)

U S hrs. 35 min.

Region I inspector reports to Region I that:

1.

R:I IRC Tapes 1.

Belief expressed that S/G pressure transient probably lifted S/t'. Safety CJhs Reliefs.

O 2.

No one had been evacuated from site yet.

3.

No consideration of offsite evacuation yet.

4.

Licensee reported to have stated have no significant leakage.

5.

No significant offsite activity reported yet.

24 (next page is 26)

_1.

El_AfMDTIM(

EVENT DESCRIPTION REFERENCES S hrs. 42 min.

RCS Pressure at 2000 psi, Pressurizer level at 400 inches, Pressurizer surge 1.

Plant Strip Charts 0

and temperature 302 F.

2.

Line Pr inter 5 brs 44 min.

RCS Pressure rises to 2050 psi and exhibits oscillating behavior between 2050 1.

Plant Strip Charts psig and 2200 psig, indicative of relief valve or Safety Valve operation. EH0V 2.

Line Printer and safety valve tallpipe temperatures alarm high (205-215oF). P3 knowledge at this time block valve on EMOV opened, or if operators used block valve to control pressure.

5 hrs. 54 min.

Decay heat cooling pumps 1 "A" and 1 "B" off.

1.

Line Printer 6-7 brs.

Note:

RCS Pressure cycled between 2050 and 2200 psig throughout the period.

1.

Plant Strip Charts Reactor building pressure remained in the range of 1.8 to 2.4 psig.

2.

B&W Figures.

Pressurizer at 400 inches.

llooked up RID neasuring device to terminals from T RTDs. Readings in-1.

Interview Note:

dicated ter.peratures s11ghtly in excess of 71DoF. hInitially, temperature r%s) readings were not believed due to their magnitude and the fact that the r%s) readings were outside the calibrated range of the instruments. All per-CJhs s nnel felt the core was covered.

E #4 f, hi s. 10 min. +

Airborne Levels in Unit 2 Control Room require evacuation of all but essential 1.

R:I IRC Tapes personnel.

C7' 6 hrs. 11 min.

Pressurizer heater groups I and 2 trip but are reenergized in 27 seconds.

1.

Line Printer

" %J t

26

II APSFD TIME EVENT DESCRIPTION REFCRENCES Region I inspector reports:

6 hrs. 14 min.

l.

reported 140 uc/cc gross 8-y activity in RCS 1.

R:I IRC Tapes 2.

concerned "B" S/G primary + secondary leak may lead to burp of activity 1.

R:I IRC Tapes from safety reliefs. Water level high at 451.

6 hrs. 15 min.

"Still injecting" and BWST level dropping based on report frau Region I inspector.

1.

RI Incident Messageform 2.

R:I 1RC Tapes Region I inspector reports:

6 brs il min.

1.

Unit 2 people having to don masks 1.

RI Incident Messagefonn 2.

Usino "A* Sir,. cooling. Believed natural circulation was working.

1.

R:I IRC Tapes 6 he s. 2/ min.

Everyone moved to Unit 1 CR except essential personnel.

1.

R:I IRC Tapes 6 hr.. 52 min.

Low Vacuum Trip, Feedwater Turbine A 1.

Line Printer f

N Note:

Not many lef t Control Room as result of evacuation order.

1.

Interview u

Note:

Door to Unit 2 Control Room without automatic recloser. People failed 1.

Interview to close on their own, possibly compromising recirculating ventilation system).

@ 6 hrs. % min.

NRC Inspector reports trying to cooldown using "A" S/G and Atmospheric 1.

RI Incident OO Dtsups. Possible Bubble in both RC punp legs;37 feet lef t in BWST.

Nessageforci Pressurizer Level > 400*.

Feeding "A" S/G with Emergency Feed.

2.

R:1 IRC Tapes Level in Containment indicating >6', which is maximum possible level indication.

1.

R:I IRC Tapes Noise level in. Unit 2 Control Room reported to be high with 20+ people.

1.

Interview I

27

l I L Al' Sill IIMI EVENT DESCRIPTION REFERENCES

$7 his.

Station Superintendent in charge in Unit 2 Control Room with major decisions nede 1.

Interviews in Shif t Supervisor's office in conference with senior staff members. Once decision was made, operators were then directed to perform required manipulations, s/ hrs.

Communications in Unit 2 Control Room hampered by respirators.

1.

Interviews Tour of Auxiliary Building found 10 R/hr at the Rad Waste Panel, water standing 1.

Interviews on the floor in areas with floor drains and the Auxiliary Building Sumps full.

Reluctant to start RCP for fear of vibration induced seal failure and resultant 1.

Interviews LOCA. Recognized had steam bubble in both loops. Personnel believed core was I

covered and considered potential of uncovering core as each option was reviewed.

'wnunications problems lead some personnel to remove respirators for short riods. Were experiencing trouble nalntaining adequate letdown flow. Concern

,e e-failure of EMOV block valve in open position lead to decision to use i

Preisurizer Vent Valves for pressure reductions.

7 hrs.

Still feeding "A" S/G and using dumps 1.

R! incident Messageform 7 hrs. 4 min.

U2 Ventilation System isolated.

1.

RI Incident Messageform l

2.

R:I IRC Tapes i

1.

NRC expresses concern that above may lead to Ground Level Release.

1.

R:t IRC Tapes 3.

Unit 2 Control Room in Respirators.

rd Note:

State reportedly urged shutdown of Auxiliary Building Ventilation to 1.

Interview u s; m

limit further releases.

CJN LN W

28

i i

h II AILSID JIME EVENT DESCRIPTION REFERENCES 7 hrs. 9 min.

EFW Pump 2A on.

1.

Line Printer 7 hr s. 19 min.

EfW Pump 2A off.

1.

Line Printer s7 hrs. 30 min.

Reported that Pressurizer lleaters were tnavailable. Concerned that EMOV block 1.

Interview valve might fall open. Decided to drop pressure.

I Didn't appear to be getting anywhere so group decided to drop pressure to get 1.

Interview Core Flood Tanks (CFT) float on core.

Were controlling pressure with the liPI and EMnV. Were concerned itPI might be i.

Interview bypassing core since T s620. Tc s220 and Pressurizer Water Space RTD was rel-atively t.onstant at 35 F.

Wanted to make sure core was covered so decided to I

depressurize.

+

Note:

Steam Tables were referred to several times by Control Room personnel 1.

Interview during sequence.

7 hrs. 30 tain.

Operator opens electromatic relief valve to depressurize RCS to attempt initiation 1.

B&W Sequence of DilR at 400 psi, interlock at 430 psig. B&W sequence states that EMOV block 2.

B&W Figures valve was opened at this point. Reactor Building pressure shows rise from low 3.

Plant Strip Charts point of 0.2 psig to 2.5 psf g during this RCS depressurization.

7 brs. 40 min.

"B S/G is bottled, but appears may have to relieve its pressure.

1.

R:I IRC Tapes N

Os i

i u 6

I C

29

~

ti APSID 11ME EVENT DESCRIPTION REFERENCES 7 hes. 40 min.

Region I inspector reports that licensee thinks they have release under control 1.

RI Incident Messageform f.er superintendent.

t I

i 7 brs. 42 min.

ESF A&B bypassed. Reactor Pressure at that time is 1650 psf. Believed to be 1.

Line Printer l

operator action to prevent inadvertant actuation of IIPI during depressurization.

2.

Plant Strip Charts l

7 hrs. 44 min.

Pressurizer heater groups 1 and 2 trip but are reenergized within 2 seconds.

1.

Line Printer 7 hrs. 50 min.

Pressurizer heater groups 1 and 2 trip and remain in a tripped state for 2 hrs.

1.

Line Printer j

16 min. At this time, there are no more than 7 heater groups operable.

Note:

Throughout depressurization pressurizer level did not change from 400 1.

B&W Figures Inch indication. Reactor pressure decrease also shows discontinuity 2.

Plant Strip Charts at 1400 psig at about this time.

}

7 hrs. 55 min. +

Using atmospheric dumps now. Unit I reported to be in llot Standby.

1.

R:I IRC Tapes 8 brs. e As the operators reduced pressure, they had even greater problems maintaining 1.

Interview adequate letdown flow. Personnel hesitated to take corrective action for I

concerns relative to NRC tolerance of deliberate over-exposure required to manipulate those valves necessary to regain adequate flow.

N H hrs 12 min.

liigh level indicated on core flood tank A (13.3 feet of water). RCS pressure 1.

Line Printer g

at that point was approximately 800 psi.

2.

Plant Strip Charts W

8 hrs. 20 min.

Pressurizer level is off scale high. Believe bubble exists in S/Gs.

1.

R:I 1RC Tapes 8 hrs. 33 r.;ln.

Decay heat cooling pumps lA and 1B started.

1.

Line Printer N

8 hrs. 41 min.

RCS pressure reaches 600 psig which is equivalent to the nominal gas pressure 1.

B&W Sequence i

maintained in the Core Flood Tank (CFT) nitrogen cover gas.

2.

Plant Strip Charts 30 i

..e..w..

~

___ a a.

Lil A.l$fl! IIM.f_

EVEN1 DESCRIPTION RffERENCES 0 hrs. 43 min.

32' BWST, RCS pressure 576 psig.

1.

RI Incident Messageform 2.

R:I IRC Tapes 8 hr s. 55 min.

"A" Core Flood Tank alarm clears.

1.

Line Printer

'9 brs.

Vere feeding "A" S/G with condensate pumps and still steaming out atmospheric 1.

Interview teliefs. State had nude several calls requesting releases be secured, each time more militant. Inspector pointed out to Station Superintendent that source of water was probably contaminated. Superintendent pay have been unaware that S/G feed had been shif ted from Emergency feedwater (Condensate Storage Tanks) to Main Condensate (Condensate Storage Tank via Main Condenser).

f 9 hrs.

General conditions:

?

1.

RCS Pressure 500 psig.

1.

B&W figures 2.

Reactor Building pressure 2.6 psig.

2.

Plant Strip Charts 3.

Pressurizer level 400 inches.

4.

Steam Generator "A" - 1001 level indicated on operating range instrument; indicated pressure O psig.

5.

Steam Gererator "B" - 60% level and 250 psig (pressure slowly decreasing).

9 hrs.

Unit I Control Roan going on mast s.

Excess personnel moved to Observation 1.

RI Incident Messageform INw)

Center.

2.

RI IRC Tapes j

N c3ns 9 his. 4 min.

Make-up pump 1C tripped. Pump 1B still operating.

1.

Line Printer

( e4 rs) 31 e

- - -.. -. -. ~ - -.

Ital' SED TIME EVENT DESCRIPTION REFERENCES 9 hrs. 15 min.

Region I informed that Condenser is isolated.

1.

RI Incident Messagefonn 1.

Reported Harrisburg TP Exit at 25 mr/hr using uncalibrated 1.istrument.

1.

R:I 1RC Tapes 2.

Core Flood Tanks have pat tially injected.

3.

BWST now at 31 feet. 600 psig in RCS.

4.

Hoping Core Flood Injection will drop tenperature allowing use of Decay Heat 1.

R:1 IRC Tapes Renoval (DHR) system.

~9 hrs. 15 min. +

Personnel felt core was demonstrated to be covered when CFT level dropped only 1.

Interview slightly upon dropping RCS pressure below CFT blanket pressure. Attributed in-ability to drop below 450 psig as sign had reached saturation pressure of loops.

Would be unable to depressurize further without some riechanism for co611ng those loops.

9 hrs. 17 min.

Operator closes EMOV Block Valve, Core Flood Tanks indicate slow discharge. No 1.

Operating Logs indications of changes seen on RCS pressure or pressurizer level instrumentation.

2.

Plant Strip Charts l

Pressurizer still at 400 inches. Reactor Building at 2.6 psig and decreasing.

3.

B&W Figures i

Logs indicate "gyped M" (Initiation time not known - rJt confirmed by line printer).

N i

9:15

• 9:18 NRC inspector reports steam dumps closed.

1.

RI Incident Messageform g

O NRC expresses concern that leaving Core Flood Tank isolation valves open may 1.

R:1 IRC Tapes U

lead to injecting N into vessel.

g 9 hrs. 22 min.

EMOV tallpipe temperatures showirg decrease.

1.

Line Printer l

N U

s 32

t EIAP5tD TIME EVENT DESCRIPTION REFERENCES 9 hrs. 30 min.

Reactor Building pressure 1.6 psig. SRM count rate continuing to show slowly in-1.

Plant Strip Charts creasing level.

2.

Operating t ogs I

Region I inspector reports from site that State of Pennsylvania was concerned 1.

R:I 1RC Tapes about Stear Dump.

9 hrs. 35 min.

Region I inspector, in response to question, states to Region that Pressurizer 1.

RI Incident Messagefonn relief valve is closed.

2.

R:1 IRC Tapes 9 hrs. 45 min.

Region I inspector reports to Regional Office that DitR will be initiated when 1.

C-14 of RI Incident Messagefonn RCS pressure gets to about 350 psig.

1.

Rx Press s500 psig.

1.

R:I IRC Tapes 0

2.

Temperature s250 F.

3.

Pressurizer being vented to Vent Header.

4.

Normal letdown in operation.

f 5.

Pumping Bleed Tank to Core Flood Tanks to complete water cycle.

9 hi s. 50 min.

ESF actuation by high building pressure. Dutiding pressure experienced spike 1.

Line Printer I

N to 28 psig (indicated) af ter reaching low of 1.4 psig. Building spray pumps on 2.

Plant Strip Charts l

,N within 6 seconds and 30 psig actuation clears within 11 seconds. Not able to confino at this tine if pressure strike of similar magnitude exhibited in RCDT.

! u&

RCS pressure shows rapid 50 psi decrease and recovery to 500 psig at that sane j

tine. Makeup pump IC starts (10 already operating). Makeup pun.p IC tripped in 40 seconds.

'N Operator reports that the alann occurred simultaneous with his opening of the 1.

Interview A

EMOV. Shif t Supervisor believed he had a " noise" or electrical cross connection which yleided " false" signal. Supervisor requested aid from instrumentation people.

Some question exists as to whether this infonnation was passed to management on I

site.

33

E L aphid Tl!q EVENT DESCRIPTION REFERENCES 9 hrs. 55 min.

Unit 1 CR still in Respirators.

1.

R:1 IRC Tapes 9 brs 55 min.

Pressurizer heater group 8 trips and remains tripped for the remainder of the in-1.

Line Printer cident. At this time, no more than 6 heater groups are operable.

9 brs. 56 min.

Reactor Dullding spray was shut down.

1.

Iine Printer 2.

Operator Interviews 9 hrs. 58 min.

Core flood tank A level alarms indicate varying levels over the next 1 1/2 hours, I.

Line Printer between a low of 12.3 feet to a high level at or above 14 feet. During this 2.

Plant Strip Charts period RCS pressure slowly increased to 560 psig. These alarms continued inter-mittently ove.c a period of approximately 1 1/2 hours.

10 hrs. 6 min.

Pressurizer heater groups 1 and 2 return to normal but trip again within 1 min.

1.

Line Printer 54 seconds.

10 hrs.15 rain.

RCS Pressure s500 psig.

1.

R:1 IRC Tapes Th 600 F T 2300F c

Suspect Bubble in Loops Reported to be Venting Pressurizer N

N Ch t

6

'Ln 34 i

ll APSI D_I.lMf_

EVENT DESCRIPTION REFERENCES slo hrs. 26 mins.

1.

Licensee reported to believe release coming from Aux. Buildings Floor Drains.

1.

R:I IRC Tapes Reading 1-2 R/hr in area of Rad Waste Control Panels.

i 2.

All TMI-2 Water Tanks are full.

3.

Going to dump IMI-2 Neutralizing Waste Tank to THI-l Miscellaneous Waste Tank, then dump that water to floor of TMI-l Bleed Tank Room (apparently this technique of shif ting water had been used year before), then pump TMI-2 Aux.

Building sumps to various TMI-l and 2 Tanks.

4.

Some places in Aux. Building, water was 6-8" deep, usually in areas of floor drains.

10 hrs. 23 min.

Rapid drop in RCS temperature noted and operators believe bubble has moved.

1.

Operating Logs 2.

Plant Strip Charts 3.

B&W Figures Note:

Although hot leg temperature came on scale, Tay indicatiog was still erroneous due to cold leg temperature remaining below 520 f.

lo hrs. 30 min.

Pressurizer level shows slight decrease to 380 inches; begin to rise again to 1,

B&W Figures 400 inches. This level change coincides with hot leg temperature coming on

+

scale, but is a lesser magnitude than would be expected under normal conditions N

for the indicated hot leg temperature change.

N "A" S/G pressure begins to increase following reported collapse of bubble in "A" 1.

Interviews loops.

2.

B&W Figures g

I 10 hrs 32 min.

Makeup pump 1C started, trips in 3 seconds and restarted 2 seconds later. Pumps 1.

Line Printer 1B and 1C now operating.

N 10 hrs. 33 min.

Pressurizer heater groups 1 and 2 return to normal but trip again with 61/2 min.

1.

Line Printer They are returned to normal within another minute. There are now not more than 8 operable pressurizer heater groups.

35

O r

II AP5FD TIMF EVENT DESCRIPTION REFERENCES r

10 hrs. :16 min.

Make-up Pump IC tripped off.

1.

Line Printer slo hrs. 41 min. t 1.

All the Auxiliary Building Sumps are full.

1.

R:I IRC Tape 2.

A Region I ilP indicated his tour of Auxiliary. Building identified no visible leaks, just water on floor.

10 hrs. 45 min.

Operators note that hot leg temperature returning on scale again. Pressurizer 1.

Interviews level starts steady decrease to 180 inches from 400 inches (minimum level 2.

B&W Figures reached at about 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> 24 minutes).

slo brs. 57 min.

Region I inspector reports current status to be:

1.

R:I IRC Tape T 550"f T 200 F l

0 R S Press 450 psig Plan to go into DllR via BWST.

Use flow path BWST + DHRP + Core N

N Ch u

?

I

-ma

• %J sj 36 i

l

[t Af'5E D TIMf_

EVENT DESCRIPTION REFERENCES At the request of State Governnent, VP-Generation Station Superintendent, 1.

Interview and Unit 2 Technical Superintendent reported to Governor's of fice. Energency Director Designee was directed to maintain the status quo, if possible, during a

their absence. Station Superintendent was fitted with a beeper to pennit him to be signalled in the event of a change in conditions.

11 hrs. +

Reported plan to Low Pressure injection followed by normal hot leg cooldown 1.

R:I IRC Tape f

using DilR.

NRC:HQ requests clarification of 16-18 hour estimate to get on DIR. Told cooling 1.

R:I IRC Tape down at 30f/hr, that there is an interlock on DIR valves at 430 psig, that currently at 450 psig, that to be conservative had assuned would wait to shif t i

over to DilR until arrived at 400 psig. Thus 18 hr estimate.

I 11 brs. 10 min.

Operators authorized to remove respirators in control room.

1.

Operating Logs 2.

R:I IRC Tape 3.

Interview I

sll brs. 12 min.

Feed coming from condensate storage. Steaming out of atmospheric reliefs.

1.

R:t IRC Tape Reported no radioactivity at these reliefs. Using atmospheric reliefs since have no condensor vaccum. Lost Turbine Seals after no longer able to get steam from Unit 1.

N Note:

During the next 15 minutes, the level in steam generator "B" is raised 1.

B&W Figures

, Ch to approximately 90% and pressure in that generator drops from about 2.

Plant Strip Charts u

250 psig to 150 psig and stab 11zes.

l Not now cooling down S/Gs. Have stopped because of fear of secondary contam-1.

R:I 1RC Tape ination.

CO sll hrs. 15 min.

Comenced efforts to draw vacuum in condenser.

1.

Interview 11 hr. 15 min.

Suction from BWST, 5A and B, new open, MUP running, supplying water to RCS via 1.

R:I IRC Tape 16 valves which are used to throttle flow when the pumps are running in the HPI mode.

37

I t

FI APLE D lltti EVENT DESCRIPTION REFERENCES 11 hrs. la min.

Loop A cold leg temperature starts rapid increase from 200 F to 4000F, RCS 1.

B&W Sequence pressure rapid increase of 50 psig.

2.

B&W Figures 3.

Plant Strip Charts 11 hes. 19 min.

Makeup pump IC started and runs for less than 10 minutes and tripped. Restarted within 5 minutes and runs for 3 minutes untti 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> and 36 minutes.

11 brs. 24 min.

Pressurizer level begins steady increase to 400 inches from 180 inches, reaches 1.

B&W Figures 400 inches at 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, 30 minutes.

sl1 hr s 28 min.

• Only one 16 valve open. Pressurizer level 175" (Per Operator in Unit 1 Control 1.

R:I 1RC Tape Room speaking to Region I office - potential time lag).

Periodically bumping electromatic. Worried continued burping relief might cause it to fall. Failure l

mode uncertain. Not using S/G cooling at all at this point.

11 hrs. 29 min.

Pressurizer heater groups 1 and 2 trip but are returned to noraal within 17 mins.

1.

Line Printer l

\\

11 brs. 32 min.

Operators indicate method of cooldown at this time is one high pressure injection 1.

Operating Logs i

pump and the core flood tanks. (Region I Incident Messageform states pressurizer 2.

RI incident Messageform 8

level 166" and periodically cycling EMOV).

11 hrs. 34 min.

North Gate 30 mr/hr.

1.

RI Incident Messageform 2.

R:1 IRC Tape j

N 11 brs. 36 min.

AfW pump 2B turned on and shut down 16 minutes later.

1.

Line Printer g

sll hrs. 43 min.

Reported readings from Unit 2.

1.

R:I 1RC Tape U

RB Pressure 0 psig i _._.

PZR Level 170" y

PIR lemp.

4600F PZR Press.

450 psig sll hrs. W min.

NRC senior manager asks licensee operator (over telephone) to connunicate NRC 1.

R:I 1RC Tape concern that Pressurizer level indication does not preclude bubble in core, that temperature readings indicating superheat may be real and implying core is uncovered. Would then need to put water into core.

(

38

i ilAl % D TIMF_

EVENT DESCRIPTION REFERENCES 12 hrs.10 min.

Report incore temperatures unavailable (computer or sensor problem). State Core 1.

RI Incident Messageform Flood Tanks floating on core, one Th 590*F, other " pegged."

2.

R:I 1RC Tape Region ! Inspector reports to Region that:

12 hrs. 10 min. +

1.

licensee believes no bubble in core since Core Flood Tanks 1.

R:I IRC Tape sit on top of core and only a little water " slid in."

2.

licensee NOT planning to use electromatic to blowdown because 1.

R:I IRC Tape l

could fall open with resulting rapid cooldown that could overstress RCS.

12 hrs. 30 min.

3.

"We're going to decrease pressure. What we're going to do is 1.

R:I 1RC Tape open that electromatic."

s12 hrs. 30 min.

1.

Unit 1 Control Room is back in masks.

1.

R:I IRC i

2.

NRC:llQ now reported to have Unit 2 on line.

12 hrs. 30 min.

Pressurizer level 400 inches. B&W Sequence indicates llPI flow increased to 400 1.

B&W Figures N

9pm. (Not confirmed at this point).

2.

B&W Sequence N

12 hrs. 30 min.

Opening EMOV to depressurize.

1.

RI Incident Messageform 2.

R:1 IRC Tape I

312 hrs. 30 min. +

NRC Inspector on line in Unit 2 Control Room. Reports following:

1.

R:1 IRC Tape j

I CO 1.

Originally had bubble in both loops.

C~3 2.

llave collapsed bubble in "A" loop.

3.

Ilad bubble in pressurizer but just lost it.

4.

Floating Flood Tanks on core and got some injection.

39

.a_.._.....

EIAPSfD TIME EVENT DESCRIPTION REFERENCES 5.

Normal letdown at 120 gpm.

l t

6.

Makeup Pumps feeding from BWST.

i 7.

B&W Calculations indicate 120 gpm insufficient to remove current core decay heat.

8.

Operating electromatic relief and (Pressurtzer Vent Valves) periodically to remove additional heat.

9.

Plan is to establish vacuum in condenser, steam "A" S/G and remove core heat through natural circulation.

12 hrs. 30 min. &

Note:

Reported licensee believes A loop is solid since: Original Th (AAB loops) $7000 with Tc s2250; Directed MU to A loop to collapse steam bubble and its Th dropped quite rapidly to s5750F. At the same time PZR level droppd considerably and curve back on scale.

12 hrs. 35 min.

Tallpipe temperature alarms received on EMOV and both pressurizer safety valves.

1.

Line Printer s12 hrs. 45 min.

"A" loop Th reported s5800F.

1.

R:I IRC Tape I)

12 krs. 45 min.

Region I inspector reports conditions are: pressure 450-500, continuing normal 1.

RI Incident Messageform

'l I)

letdown (120 gpm), and EMOV opening intermittently. Lowest pressure reached 2.

R:I IRC Tape CDPs 450 psig during blowdown and it just " hung" there. Nothing tried so far could

(,nJ drive it lower.

40 j

i

~

H APSElj 1ptf EVENT DESCRIPTION REFERENCES 12 hrs. 56 min. +

NRC Inspector reports the following:

1.

R:I IRC Tape 1.

Licensee concerned that current cooldrwn process is too slow and believe will be faster steaming S/G.

2.

Licensee working to get rid of bubbles in loops, establish bubble in pressurizer and go on natural circulation.

3.

Licensee concerned for further use of electromatic since water dumps to floor, and with sources of clean water being exhausted, would be forced to I

use dirty sump water for recirculation.

li 4.

Licensee concluded core was covered. Discussed and rejected further blowdown since would ultimately entall recirculation of sump water, i

greatly increasing magnitude of cleanup. Discussed and rejected I

repressurization to collapse all bubbles. Latter discussion may have j

been result of B&W input.

5.

llave regained some pressurizer heaters.

6.

Plan to draw condenser vacuum using THI-2 Mechanical Vacuum Pumps and TMI-l steam for Turbine Gland Seal. Itaving problems because of high radiation and contamination levels.

N 13 hrs. 5 min.

Starting to draw vacuum. Confident no bubble in "A" S/G loop. Press 650 1.

RI Incident Messagefonn psigandPlRlevel40{f. decreasing. Continuing normal letdown and makeup.

2.

R:I IRC Tape CD Thas530 f and Thbs700 3.

Interview u

13 hrs 20 min.

Reactor Pu11 ding pressure zero. Operators note reactor cooling system going 1.

Operating Logs solid again. Previous small change in pressurizer level was noted. Operators 2.

RI Incident Messageform Q

note pressurizer level starting to drop and RCS pressure dropping. (Present I

N value 636 psig). Seal injection flow 60 gpm. IIPI flow 425 gpm and BWST leyel 26 1/2 ft. Report continued operation of electromatic relief, starting to steam "A" S/G to condenser.

a 1

41

~

ELAPSED TIME EVENT DESCRIPTION REFERENCES sl3 hrs. 23 min.

Reported by Region i Inspector:

1.

R:I IRC Tape 1.

15" Vacuum in Condenser.

2.

Just starting to steam now.

4 3.

s650 psig.

Thb 650-700 F 570-580 F l

T Tcbha & a 2250F i

4.

Electromatic Relief indicates closed.

13 hrs. 23 min.

Makeup pump IC started.

1.

Line Printer 13 hrs. 26 min.

Pressurizer heater groups I and 2 trip. At this time there are now no more than 1.

Line Printer 6 operable pressurizer heater groups.

13 hrs. 30 min.

Electromatic relief valve closed to: repressurize RCS, collapse voids, and 1.

IE Bulletin 79-05A prepare to start RC pump. Plant charts confim pressure increase, but unable 2.

Line Printer to confinn closure of EMOV block valve. Ilowever, at 13 hrs. 25 minutes, line l

printer shows tailpipe temperature returning to normal.

i N

Note:

Regarding decision to repressurize RCS, interviews indicate that Control 1.

Interview N

Room personnel had desired to remain in depressurized state since had regained Pressurizer Level, appeared to have collapsed bubble in "A" f

u loop and were progressing on doing same to "B" loop.

Af ter decision to pressurize, Control Room personnel reconnend restart m

of RCP to sweep vapor from loop.

U 13 hrs. 32 min.

RCS Pressure 625 psig.

1.

Operating Logs l

11 hrs. 35 min.

RCS Pressure 645 psig.

1.

Operating Logs 42

E LAP 5f D TIME EVENT DESCRIPTION REFER [NCES 13 hrs. 31 min.

RCS Pressure 660 psig.

1 Operating Logs 13 hrs. 40 min.

RCS Pressure 675 psig.

1.

Operating Logs 13 brs. 40 min.

"A" S/G valve not opening - not steaming. Bleed valve for generator to condenser.

1.

RI Incident Messageforu Start investigating. Indicator must be in error.

2.

R:I 1RC Tape 13 hrs. 41 min.

RCS Pressure 690 psig.

1.

Operating Logs 13 hrs. 42 min.

RCS Pressure 705 psig.

1.

Operating Logs j

sl3 hrs. 45 min.

Reactor Building Pressure is -0.2 psig.

1.

R:I IRC Tape a

13 hrs. 50 min.

RCS Pressure 765 psig. (Pressurizer level 285 inches).

1.

Operating Logs 13 hrs. 50 min.

"A" S/G started steaming using turbine bypass valves to condenser. Indication 1.

RI incident Hessageform of level (hange in steam generator and indication of feedwater flow.

2.

R:1 IPC lape i

13 hrs. 50 min.

• Not now wearing respirators in IMI-2 Control Room.

7 R:I 1RC Tape 13 hrs. 55 min.

RCS Pressure 800 psig.

1.

Operating Logs I ')

13 hrs. 58 min.

RCS Pressure 835 psig.

1.

Operating Logs N

CJh*

14 hrs. O Min.

RCS Pressure 860 psig.

1.

Operating Lors U

14 hrs.

Region I Inspector reports BWST 23'.

1.

RI Incident Hessageform

.gm.

43

~

d l L_ APSI!Li t t!!:

EVENT [lESCRIPTION REFERENCES 14 hrs.

• 1.

Region I Inspector reports: Licensee staff or senior management have concern 1.

R:I IRC Tape whether core covered or not.

2.

The plan has changed now. Licensee plans to continue cooldown by steaming.

"A" S/G Th now 5480F, T now 4460F. They increased makeup to 480 gpm with letdown at 40 gpm, Setting pressure increase and plan to take plant solid at s2000 psig to collapse all bubbles.

14 hrs. 4 min.

RCS Pressure 900 psig.

1.

Operating Logs 14 hrs. I min.

RCS Pressure 945 psig. (BWST 24 ft.)

1.

Operating Logs j

I 14 hes. 10 min.

RCS Pressure 1012 psig (Pressurizer level 370 inches).

1.

Operating Logs 14 hrs. 15 min.

RCS Pressure 1120 psig.

1.

Operating Logs n.14 hrs. 17 min.

• Region I Inspector reports:

1.

R:1 1RC Tape 1.

Continuing coolJown of "A" S/G. The AT for "A" loop is increasing.

555 Thb 650-700(*)

2.

RI Incident Messageform Tha I ca 300 Tcb 200 N

(*) = Old data from last time B&W manually read back panel Thermocouple N

or RID parameters.

O 2.

Makeup at 450 gpen. Pressure 1100 psig increasing, Pressurizer full but pressure g

increase indicates bubble still exists somewhere in system.

3.

Using condensate pumps, not emergency feed, for S/G.

CD w

14 hrs. 20 min.

RCS Pressure 1200 psig (PresArizer level 400 inches and BWST level 23 ft.).

1.

Operating Logs l

i 44 e

7....

l it APSID JIMl_

EVENT DESCRIPTION REFERFNCES sl4 hrs. 29 min.

Region I Inspector reports:

1.

R:I IRC Tape i

1.

S/G 1evel s901, i

2.

27" Vacuum in condenser.

I 3.

Main Steam Bypass valve indicates 30% open.

I 14 hrs. 26 min.

Pressurizer heater groups 1 and 2 return to normal. There are now no more than 1.

Line Printer 8 operable pressurizer heaters.

14 hrs. 30 min.

RCS Pressure 1520 psig (at approximately this time, the SRM count rate showed a 1.

Operating Logs rapid rise and then decayed to a point below its starting value).

2.

Plant Strip Charts 14 hrs. 33 min.

RCS Pressure 1700 psig (Line printer shows 1600 pst interlock cleared at 32 1.

Operating Logs minutes).

2.

Line Printer sl4 hrs. 34 min.

Region i Inspector reports:

1.

R:I 1RC Tape 1.

Still steaming "A" S/G, but indications not getting much natural circulation.

2.

T s5700F, T $2200F; one Incore T/C reads 570, indicating Th may be accurate; I

0 oNer T/Cs c8 not be read.

B&W Site Representative contacts B&W at Lynchburg who indicate that they had also 1.

Interview come to conclusion that licensee should repressurize and start a RCP.

N 14 hrs. 34 min.

RCS Pressure 1781 psig.

1.

Line Printer g

14 hrs. 35 min.

RCS Pressure 1800 psig.

1.

Operating Logs T =570. T =220 2.

RI Incident Messageform j

h c

g 14 hrs. 35 min

• Region I Inspector reports:

1.

R:I 1RC Tape 1

1.

1800 psig increasing.

2.

Indication some bubbles may be collapsing since have seen some temperature changes.

45

~

F I

I I

EI APMD TIME EVENT DESCRIPTION REFERENCES I

l 14 hrs. 39 min.

RCS Pressure 2080 psig. Operators throttling HPI flow to 120 gpm by manipulating 1.

Operating Logs valve 16B.

14 hrs. 40 min.

RCS Pressure 2140 psig.

1.

Operating Logs 14 hrs. 41 min.

Operators throttling valve 16C. HPI flow 120 gpm, RCS Pressure 2220 psig.

1.

Operating Logs 14 hrs. 4 3 min.

Valve 16C closed. RC Pressure 2275. Makeup Pump 1C tripped.

1.

Operating Logs f

2.

Line Printer 14 hrs. 45 min +

Region I Inspector reports:

1.

R:I 1RC Tape 1.

Press s2300 psig.

2.

See Later Confirmation at 14:52 2.

Appears still have bubble in "B" loop.

RI Incident Hessageform 3.

Makeup and Letdown at 150 gpm.

I i

0 ha 560. T, 320.

4.

T c

5.

Steaming s100.000 f/hr based on constant S/G 1evel and rate of feeding.

I 6.

Level in S/G at s93%.

N 14 hrs. 45 min.

Operators beginning preparation to start a reactor coolant pump.

1.

Operating Logs Control Room personnel recommended only bumping RCP, as would normally be done 1.

Interview following routine loop ref t11.

14 hrs. 47 min.

RCS Pressure 2300 psig. Steaming from "A" steam generator to condenser; one 1.

Operating Logs CO makcup pump in operation; 80 gpm letdown; 32 gpm seal injection; 20 gpm makeup; i

N BWST 22 ft.

46

1 ELAP3ED TittE EVENT DESCRIPTION REFERENCES 14 hrs. 52 min.

Region I Inspector reports RCS 2300, Bubble s*'ll in "B" loop, "A" loop T = 560, 1.

RI Incident Messagefonn h

Tc=320, 100,000 f/hr condensate flow in "B" steam generator "A" steam generator 50 psi.

i 15 hrs.

1.

Reports Th dropping slowly. Tc rising slowly. Believe getting soaie 1.

R:I IRC Tape natural circulation flow, but still very little.

2.

Licensee has c'nsidered starting RCP, but unable to do so since has lost power to RCP oil pumps. llaving problems restoring power to oil pump bus because of high radiation and contamination levels.

15 hrs.

B&W in Lynchburg has been contacted and is doing calculations for TMI.

1.

R:I IRC Tape Proceeding to attempt start of a RCP.

15 hrs.

Inspector reports T a=560, T a=360 Tcn=2200 1.

RI Incident Messagefonn h

c Thb of f scale high 2300 psig 2.

R:I IRC Tape 15 hrs. 4 min.

IlQ-NRC were of opinion might have to bump RCP to clear " candy-cane" of voids 1.

R:I IRC Tape to a110w full natural circulation, since trend of parameters strongly suggest little or no natural circulation is occurring.

15 trs. 10 min.

Inspector reports Th 557. Tc 380, B 240, 2300 psig.

1.

RI Incident Messagefonn Steam Generator 'B" 180 psig 2.

R:I IRC Tape Steam Generator "A" 20 psig sl5 hrs. 15 min.

1.

lleaters now on in an attempt to draw a bubble, but currently level is off 1.

R:I IRC Tape scale high.

N 2.

Since no power to A.C. RCP oil pump, trying to start D.C. RCP oli pumps.

N ON Interview indicates licensee had to send operators to Auxiliary Building to 1.

Interviews u

assist in starting RCP oil pumps.

15 hrs. ?O min.

Region I Inspector reports that BWST 22 Ft.

Still steaming; "A" loop AT decreased, 1.

RI Incident Messageform RCS Pressure 2300. Increasing Temp with heaters. Trying to steam down "A" 2.

R:I IRC Tape Q

S/G 1evel and have secured feeding it.

CO Th 560 F Tca 3950 Tcb 220 l

Makeup and Letdown 40 gpm Reacter Butiding Pressure = -0.2 psig Pressurizer Temp increasing with heaters en 47

~.

e

[ LAPSED TIME EVENT DESCRIPTION REFERENCES Note:

Reported two NRC inspectors scheduled to go to Governor's Office for 1.

R:I !RC Tape briefing at s7:30 PH.

i Note:

Reported that at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> the Gross B was less than minimum detectable 1.

R:I 1RC Tape at condensate pump discharge MDA=10x10-5 uc/ml.

Note:

Reported that have been unable to get a primary sample since 4900 hours0.0567 days <br />1.361 hours <br />0.0081 weeks <br />0.00186 months <br /> 1.

R:1 IRC Tape this morning.

15 hrs. 22 min.

Start conden'. ate booster pump.

1.

Operating Logs Note: Reported early morning sample of S/Gs were checked witt. frisker.

"B" 1.

R:I IRC Tape sample pegged meter, "A" S/G sample did nothing ta meter. Based on results, isolated "B" S/G.

15 hrs. 33 min.

Started RC pump 2A for 10 seconds. RCS Pressure dropped to approximately 1450 1.

Operating Logs psig. ESF actuation received and Hakeup Pump IC started. Pressure starts to 2.

Plant Strip Charts climb again.

3.

RI Incident Messagefonn 15 hrs. 35 miri.

Th now below 520, the lowest meter can read. T did not go up nuch. Believe got 1.

R:1 IRC Tape c

some flow. Must wait 15 minutes until can bump RCP again.

Station Superintendent consulted with B&W Representative on appropriate delay 1.

Interview before pump restart.

IS hrs. 37 min. +

Believe current plans are to run that RCP and conduct normal cooldown. When 1.

R:I IRC Tape g

bumped RCP, S/G pressure jumped from 20 psig to 200 psig, indicating did get heat transfer.

Ch U

15 brs. 40 min.

Hakeup Pump IC turned off. RCS Pressure (Loop A) 1948 psig.

1.

Operating Logs 15 hrs. 45 min. t Setting up to start and run an RCP in "A" loop.

1.

R:1 1RC Tape Station Superintendent waited appropriate delay time on RCP restart and then i

T directed operators to start RCP.

l 48

T t

f EIAPSID lIftf EVENT DESCRIPTION REFEREi!CES 15 brs. 50 min.

Makeup Pump IC started.

1.

Operating Logs 15 hrs. 51 min.

Started RCP and let it run. Flaw and amps look good. Reactor coolant pressure 1.

Operating Logs 1321 psig. (Log did not note if ES actuation received again. Time period beyond 2.

R:I IRC Tape that covered by line printer data available at this time.)

1.

Loop Temperatures:

A.

Loop Cold Leg: 340 F B.

Loop Cold Leg: 3380F 2.

Steam Generator Pressures:

A.

Generator increases from 0 to approximately 40 psig.

I B.

Generator decreases fnsn 140 psig to approximately 50 psig. (Tsat approxinately 3300F 0.

hJ CN U

ca

}

I i

49

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