Information Notice 1993-45, Degradation of Shutdown Cooling System Performance

Degradation of Shutdown Cooling System Performance

ML031070480
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	06/16/1993
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-93-045, NUDOCS 9306090036
Download: ML031070480 (9)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 June 16, 1993 NRC INFORMATION NOTICE 93-45: DEGRADATION OF SHUTDOWN COOLING

SYSTEM PERFORMANCE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees to degradation of shutdown cooling system

performance at the Oyster Creek Nuclear Generating Station resulting from

inadequate operating procedures. It is expected that recipients will review

the information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in

this information notice are not NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

On January 23, 1993, the Oyster Creek Nuclear Generating Station was in day 57 of the 14R refueling outage. The plant was in a normal cold-shutdown

condition with the primary containment open and the reactor coolant system at

about 43' C [110* F]. One reactor recirculation loop was in service, one

recirculation loop was open, and the remaining three recirculation loops were

either idled or isolated. Two shutdown cooling loops were operating with a

combined flow rate of 11,735 liters per minute 13,100 gpm].

In order to support the planned activities, the licensee elected to secure

operation of all recirculation pumps and lower reactor water level. This

configuration would allow completion, in parallel, of recirculation pump

maintenance activities and main steam isolation valve local leak rate testing.

When the operators lowered the reactor water level to approximately 419 cm

(165 inches] above the top of active fuel and secured the running.

recirculation pump, the shutdown cooling water took the least resistance path

through the open recirculation loop, and the majority of flow bypassed the

core (see Attachment 1). During the time that the planned activities were in

progress, plant personnel did not realize that shutdown cooling system

performance was degraded, allowing unmonitored heatup of the reactor core.

On January 25, 1993, after completing the main steam isolation valve local

leak rate testing, an operations engineer discovered that the reactor vessel

metal temperature was about 109C 1228F] at the mid-vessel point. Several

9306090036 PDI I.E No*[ct 3-. oj58

. . P 'v1\

IN 93-45 June 16, 1993 C [212 F] were not

Technical Specifications prerequisites for exceeding 100. integrity.

met, including the requirement to establish primary containment

measures to reduce reactor coolant

After discovery, operators took immediate two operating

system water temperature by first maximizing flow in the

cooling loop in

shutdown cooling loops and then placing a third shutdown to approximately

service. Additionally, the reactor water level was raised a recirculation pump was

508 cm [200 inches] above the top of active fuel and

started.

conditions

The immediate cause of the event was determined to be plant cooling operating

established by a temporary procedure change to the shutdown

through the reactor

procedure that failed to provide sufficient forced flow procedure change had

core to prevent thermal stratification. The temporary

pumps

been implemented to allow shutdown operations with all recirculationlevel at which

secured and the nominal reactor water level less than the (approximately 470 cm

spillover from the core region to the annulus is assured

been developed

[185 inches] above the top of active fuel). The change had a requirement (stated

from a draft engineering evaluation, but did not includeshutdown cooling flow

in the body of the evaluation) to maintain a specified shutdown cooling

of 22,712 liters per minute [6,000 gpm]. Instead, the usual which, due

flow of about 11,735 liters per minute [3,100 gpm] was maintainedheatup.

to the specified configuration, allowed the inadvertent reactor

and NRC

Further details can be found in Licensee Event Report 50-219/93-002 Augmented Inspection Team Inspection Report No. 50-219/93-80.

Discussion

change

This event at Oyster Creek indicated that the temporary procedure review process did

represented a significant procedure revision and that the

was implemented. The

not identify deficiencies in the procedure before it engineering

temporary procedure change had been developed from a draft in operation would

evaluation which concluded that two shutdown cooling loops

of the

adequately cool the core. An additional assumption in the body at its

evaluation was that each loop of shutdown cooling would be operating

gpm], for a total flow

design flow rate of 11,356 liters per minute [3,000 would be

rate of 22,712 liters per minute [6,000 gpm]. This flow rate

at the

adequate to induce spillover from the core region to the annulus that implemented

reduced nominal water level. The temporary procedure change

flow rate of 22,712 the engineering evaluation did not require a minimum the

operators following

liters per minute [6,000 gpm]. As a result, the loops in

deficient temporary procedure change placed two shutdown cooling

cooling water to the

operation, but did not provide sufficient shutdown addition, the

reactor core to maintain reactor vessel temperatures. In for monitoring

temporary procedure change contained no provision or guidance

heat was being adequately removed

available instruments to ensure that decay

from the reactor core.

the

As part of the licensee corrective actions, the licensee reviewedchanges and

effectiveness of its safety review process concerning temporary

who

provided training on the subject of this event to all site personnel

perform technical and safety reviews.

IN 93-45 June 16, 1993 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Offic of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor

Support

Office of Nuclear Reactor Regulation

Technical contacts: James S. Stewart, RI

(215) 337-5240

Peter C. Wen, NRR

(301) 504-2832 Attachments:

1. Figure 1, *Oyster Creek Shutdown Cooling System

Flow With Open Recirculation Loop"

2. List of Recently Issued NRC Information Notices

K. / I'l I

Attachment 1

1iK 93-45 June 16, 1993 Steam Flow *-

4- Open Recirculation

TORecirculation Loop

1. ~Loop

Shutdown Cooling

System

(3 Cooling Loops)

Figure 1 Oyster Creek Shutdown Cooling System Flow With Open Recirculation Loop

I

Attachment 2 IN 93-45 June 16, 1993 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

93-44 Operational Challenges 06/15/93 All holders of OLs or CPs

During A Dual-Unit for nuclear power reactors.

Transient

93-43 Use of Inappropriate 06/10/93 All holders of OLs or CPs

Lubrication Oils in for nuclear power reactors.

Safety-Related Applications

93-42 Failure of Anti-Rotation 06/09/93 All holders of OLs or CPs

Keys in Motor-Operated for nuclear power reactors.

Valves Manufactured by

Velan

93-41 One Hour Fire Endurance 05/28/93 All holders of OLs or CPs

Test Results for Thermal for nuclear power reactors.

Ceramics Kaowool, 3M

Company FS-195 and

3M Company Interam E-50

Barrier Systems

93-40 Fire Endurance Test 05/26/93 All holders of OLs or CPs

Results for Thermal for nuclear power reactors.

Ceramics FP-60 Fire

Barrier Material

,93-39 Radiation Beams from 05/25/93 All holders of OLs or CPs

Power Reactor Biolog- for nuclear power reactors.

ical Shields

93-38 Inadequate Testing of 05/24/93 All holders of OLs or CPs

Engineered Safety for nuclear power reactors.

Features Actuation

System

93-37 Eyebolts with Indeter- 05/19/93 All holders of OLs or CPs

minate Properties In- for nuclear power reactors.

stalled in Limitorque

Valve Operator Housing

Covers

0L - Operating License

CP - Construction Permit

IN 93-45 June 16, 1993 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Original !1gnd by

Brian K. Gdmeg

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: James S. Stewart, RI

(215) 337-5240

Peter C. Wen, NRR

(301) 504-283],

Attachments: 6

1. Figure 1, "Oyster Creek Shutdown Cooling System

Flow With Open Recirculation Loop'

2. List of Recently Issued NRC Information Notices

• rFF pRmVrnus CONCURRFNCF

OFFICE *OGCB:DORS *DRS:RI **SC:DRS:RI **BC:DRS:RI **D:DRS:RI

NAME PCWen/vsb JSStewart PKEapen JPDurr MWHodges

DATE 04/29/93 05/03/93 03/19/93 03/19/A3 .03/19/93

_______- _ .

• Tech Ed. I *C:OGCB:DORS-- *D:DSSA:NRR

RSanders IGHMarcus ACThadani

04/29/93 05/10 05/24/93

• • SEE MEMO FROM M.. HODGES TO B.K. GRIMES

=

.

DOCUMENT NAME: 93-45.IN

DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT

Team Leader (J. Beall) were consulted during

the development of this IN.

IN 93-XX

May xx, 1993 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: James S. Stewart, Region I

(215) 337-5240

Peter C. Wen, NRR

(301) 504-2832 Attachments:

1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation Loop

2. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCE

OFFICE *OGCB:DORS *DRS:RI **SC:DRS:RI **BC:DRS:RI **D:DRS:RI

NAME PCWen/vsb JSStewart PKEapen JPDurr MWHodges

DATE l04/29/93 l05/03/93 I 03/19/93 l 03/19/93 l03/19/93

• Tech Ed. *C:OGCB:DORS D:DORS:NRR

IRSanders GHMarcus BKGrimes

04/29/93 _ 05/10/93 ;05/ /93 4 xk)

onf~~~l oI~tsPIm

- - - - 1F

UULUIMNI NAMI: UIIrMUN .PW) **SEE MEMO FROM M.W. HODGES TO B.K. GRIMES

DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT

Team Leader (J. Beall) were consulted during

the development of this IN.

530

AV 'I/tllos

ACiwAt #

fA);mli v-

IN 93-XX

May xx, 1993 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: James S. Stewart, Region I

(215) 337-5240

Peter C. Wen, NRR

(301) 504-2832 Attachments:

1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation Loop

2. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCE .

OFFICE *OGCB:DORS DRS:RI SC:DRS:RI BC:DRS:RI D:DRS:RI

NAME PCWen/vsb 4SStewart PKEapen JPDurr MWHodges

DATE 04/29/93 05/3,0 Cal P/1/93 0/ l/9 3 I__ 1_/93_J

• Tech Ed. C:OGCB:DORS D:DORS:NRR 4xx %E memo MYS

Fizz 144 RSanders GHMarcus Ci~l BKGrimes 44 1/1 A/3

04/29/93 05/ 1q993 105/ /93 DOUUMENT NAME: OCTPCIN.PW PA (A 'rolnerlk&) , 1 (. Covte). t

AlT Team Leader (J. &3eA.A) LxQe cuAJX4A

Alxrzrl t. 4JeLt"e'4 . tk& z4BJ

IN 93-XX

May xx, 1993 Page 2 of

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: James S. Stewart, Region I

(215) 337-5240

Peter C. Wen, NRR

(301) 504-2832 Attachments:

1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation Loop

2. List of Recently Issued NRC Information Notices

OFFICE OBORS DRS:RI SC:DRS:RI BC:DRS:RI D:DRS:RI

NAME PCWen/vsb JSStewart PKEapen JPDurr MWHodges

DATE _/aq/93_ 05/ /93 05/ /93 05/ /93 105/ /93 Tech Ed. C:OGCB:DORS D: DORS:NRRI

flU"AJA& GHMarcus BKGrimes

ON/.11/93 05/ /93 05/ /93

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