Information Notice 1988-61, Control Room Habitability - Recent Reviews of Operating Experience

Control Room Habitability - Recent Reviews of Operating Experience

ML031150218
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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/11/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-061, NUDOCS 8808050248
Download: ML031150218 (12)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 11, 1988 NRC INFORMATION NOTICE NO. 88-61: CONTROL ROOM HABITABILITY - RECENT REVIEWS

OF OPERATING EXPERIENCE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to potential

problems resulting from design or analysis deficiencies identified in control

room ventilation systems. 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 do not constitute NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

The NRC has received several construction deficiency and licensee event

reports pertaining to safety systems that are used to ensure control room

habitability. These reports identified potential safety concerns resulting

from design deficiencies, which were attributed to inadequate analysis and

an inability to justify those conditions that were assumed in previous evalu- ations of plant design and operation. These reports are summarized below.

Comanche Peak 1 and 2:

On January 15, 1988, the permit holder determined that radiation doses to

control room operators for some postulated radiological accidents could

exceed the limits of General Design Criterion 19 of Appendix A to 10 CFR 50.

This determination was attributed to an inadequate analysis of control room

habitability systems for postulated radiological accidents. Particular ac- cident scenarios that were incompletely analyzed included a fuel handling

accident and a rupture of a radioactive gaseous waste tank. To correct

this situation, the licensee is developing new calculations, upgrading the

existing control room intake radiation monitors and associated cables to

safety-related Class 1E requirements, and installing two additional safety- related Class 1E radiation monitors, one in each control room intake.

88850248 '

IN 88-61 August 11, 1988 Quad Cities:

on November 25, 1987, the licensee's engineering department discovered that

design basis assumptions used in the control room habitability study were

inconsistent with technical specification requirements. The study was con- ducted to satisfy a requirement of the NRC's TMI Action Plan. The adsorption

efficiencies of the standby gas treatment system and control room HYAC system

were assumed at 99 percent for organic iodide removal. The relevant technical

specifications, however, require only an organic iodide removal efficiency more

than or equal to 90 percent. All the filters meet the technical specification

requirements. Since December 31, 1984, tests of filter efficiencies indicate

that the relevant assumptions of the study were met with two exceptions. The

licensee attributes the cause for this condition to be an inadequate review of

design and analysis during the development of the study.

Vogtle 1 and 2:

On July 2, 1987, plant engineering personnel identified an inadequacy in the

dose analysis for control room operators. On receipt of a safety injection

signal or a control room outside air intake high radiation signal, the control

room heating, ventilating, and air conditioning (HVAC) system is automatically

transferred from the normal system units to the essential control room (ECR)

fan-filter units in the emergency mode of operation. The ECR system consists

of two redundant and physically separated 100 percent capacity fan-filter units

for each side of the control room, associated with the corresponding reactor

unit (four for the combined Unit 1 and Unit 2 control room (Figure 1)). Each

of the ECR units belongs to a different safety train, but portions of the out- side air intake ductwork and control room supply and return ductwork are common

to each of the units. On initiation of the ECR system, the associated motor- operated dampers for the essential units are automatically opened and those

for the normal units are automatically closed.

When both of the ECR fan-filter units are operating, loss of power to one of

these units can reduce the amount of outside air available to pressurize the

control room. This can happen because the dampers losing power fail in the

"as-is" position. At the time of the identification of the problem, no back- draft dampers were installed. This degrades the ECR HVAC system by establishing

flowpaths through the common ductwork and the ductwork of the failed unit back

to the suction of the operating unit, which could potentially reduce the outside

air flow to the control room and reduce the control room pressure below the

design value. Maintenance of the design control room pressure is required to

minimize unfiltered inleakage.

The licensee concluded that the actual effect on control room pressure could

not be calculated in the absence of test data and decided to modify the system

by installing backdraft dampers, as noted on Figure 1, for the ECR HVAC systems

of both Units 1 and 2.

IN 88-61 August 11, 1988 On July 4, 1987, an additional condition was discovered that could have caused

an insufficient control room pressure. All ECR systems share common outside

air supply ductwork. The common air supply ductwork has intakes from the out- side atmosphere associated with both Units 1 and 2. Redundant isolation dampers

in series are provided for both Unit 1 and Unit 2 duct openings from the outside

by

atmosphere. During construction, the Unit 2 duct opening had been isolated for

locking the dampers closed. If one of the outside air isolation dampers

Unit 1 had closed as the assumed single failure of an active component, no

source of outside air would be available to the control room (shared by both

Units) and the required pressure would not be maintained. Because the licensee

had removed chlorine gas sources from the site, the capability to isolate toxic

the

gases was no longer needed. Thus, the licensee deactivated and tagged open

outside air isolation dampers.

For all these problems, the licensee concluded that the defective conditions

would have been discovered earlier with an adequate failure modes and effects

analysis.

Beaver Valley 2:

On March 27, 1987, the permit holder determined that timers initiated by con- tainment isolation phase B signals were not served with uninterruptible powerto

as required. These timers are designed to actuate banks of compressed air

supply the control room emergency pressurization system one hour after receipt

of the isolation signal. They were powered from the respective fan control

circuit energized by an emergency ac distribution panel fed from an emergency

motor control center. Loss of offsite power would interrupt power to the motor

control center. If a loss of power occurred after timer initiation, the timers

would reset to the beginning of the timing cycle and would not begin the cycle

until power was restored to the emergency motor control center. The compressed

air would thus not be supplied after one hour. To enhance the reliability of

the safety systems, the licensee revised the circuitry to power the timers from

the Class lE 125-V dc battery system.

McGuire 1:

On November 5, 1987, the licensee discovered during an 18-month surveillance

test of the control area ventilation and chilled water system that control room

pressure was below the technical specification requirement. The licensee de- termined that the cause was leaking seals on seven control room doors. The

doors were designed to seal by seating against sealing strips in the door

frames. Although not visibly deteriorated, the sealing material apparently

had been deformed and compressed over time from normal use of the doors. The

licensee adjusted manual volume dampers to increase total train air flow and

the proportion of outside air flow to the maximum 60 percent allowed in the

IN 88-61 August 11, 1988 test procedure. This action was effective in

to meet the technical specification requirement.increasing control room pressure

tape around the seven doors and established a The licensee installed sealing

preventive maintenance program to

inspect the seals on all control room doors every

The licensee plans to determine an appropriate 6 months for a 1-year period.

nance of the door seals. The surveillance test frequency for preventive mainte- and chilled water system will also be repeated of the control area ventilation

every 6 months until sufficient

information is obtained for determining an appropriate

frequency.

Farley 1:

On June 5, 1987, the licensee discovered that

control room ventilation system would fully none of four fire dampers in the

close and latch with or without air

flow because they had not been exercised and/or

lubricated or, in one case, be- cause a latch was damaged. In addition, investigation

would not have received an actuation signal revealed that the dampers

from a Firestat set to sense 1600 F

in the control room ceiling because of installation

tributed the problems to three causes: a design errors. The licensee at- full closure and latching of the dampers, inadequatedeficiency pertaining to the

circuitry, and inadequate preventive maintenance testing of the actuation

of the dampers.

Discussion:

In addition to the above, the NRC has recently

ation, "Design and Operating Deficiencies in completed an engineering evalu- Systems," AEOD/E802, April 1988 based on recentControl Room Emergency Ventilation

failure vulnerabilities in control room emergencyevents that highlight single

NRC also has recently conducted a survey of controlventilation systems.* The

at 12 operating plants. Numerous discrepancies room habitability systems

and actual performance of these systems. For were found between the analyzed

design, construction, operation, and/or testing example, differences exist between

scriptions and analyses provided in licensing of these systems and the de- documents, as for example in the

assumptions used in the toxic gas and radiation

analyses assumptions have not always been consistentdose calculations. In addition, cation requirements. The NRC has issued several with technical specifi- to this subject (see Attachment '2). Resolution information notices related

Room Habitability is also ongoing. of Generic Issue 83: Control

• A copy of the report is available in the NRC

Public

Street, N.W., Washington, D.C. 20555, for inspectionDocument Room, 1717 h

and copying.

IN 88-61 August 11, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge, NRR

(301) 492-1169 Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Figure 1. Schematic Air Flow Path Diagram of Essential Control Room

Heating, Ventilating, and Air Conditioning System (ECP HVAC) at Vogtle.

Assumed Containment Isolation Signal for Unit 1 with Train B Failed.

2. List of Information Notices Related to Control Room Habitability Systems

3. List of Recently Issued NRC Information Notices

I OUTSIDE

OUTSIDE;

L , AIR AIR% v vv

OUTSIDE AIR SUPPLY DUCT

(

(

cn c

FIGURE 1. SCHEMATIC AIR FLOW PATH DIAGRAM OF ESSENTIAL CONTROL ROOM HEATING, VENTILATING, AND LA CO 0~

AIR > o =

CONDITIONING SYSTEM (ECR HVAC) AT VOGTLE. ASSUMED CONTAINMENT ISOLATION SIGNAL FOR -C

UNIT 1 WITH TRAIN B FAILED.

0C

03

Attachment 2 IN 88-61 August 11, 1988 LIST OF INFORMATION NOTICES

RELATED TO CONTROL ROOM HABITABILITY SYSTEMS

NO. TITLE DATE

86-76 Problems Noted in Control Room August 28, 1986 Emergency Ventilation Systems

85-89 Potential Loss of Solid-State November 19, 1985 Instrumentation Following Failure

of Control Room Cooling

83-62 Failure of Redundant and Toxic Gas September 26, 1983 Detectors Positioned at Control Room

Ventilation Air Intakes

'-.dachment 3 IN 88-61 August 11. 4988 Page I of I

LIST OF RECENtLY ISSUED

NRCINFORMIATION NOTICES

InfTornation Date of

Notice No. Subject Issuance Issued to

88-60 Inadeouste Design and S/11B8 All holders of OLs

Installation of Watertight or CPsfor nuclear

Penetration Seals power reactors.

B8-04. Inadecuate Qualifitation 8/9/88 All holders of MLs

Supplerent I and Documentation of Fire or CPs for nuclear

Barrier Penetration Seals power reactors.

88-59 Kain Steam Isolation Valve 819/88 All holders of OLs

Guide Rail Failure at or CFs for nuclear

Waterford Unit 3 power reactors.

88-58 Potential Probiems with 8/8/E8 All holders of OLs

ASEABrown Boveri TE-S1L or CPs 'or nuclear

Time-COercurrent Pelays power oeactors.

88-57 Potential Loss of Safe 8/8/88 All holders of QLs

Shutccwn Eoulprent Due to or CFs for nuclear

Premature Siliccr Controllee power reactors.

Rectifier Failure

88-56 Potential Prcblems wtth 8/4/88 All holders of OLs

Siliccre Foam Fire Barrier or CFs 'or nuclear

Penetration Seals power reactors.

88-55 Potential Problems Caused 8/3/18 All holders of CIs

by Sirgle Failure of an or CPs for nuclear

Engineered Safety Feature power reactors.

Swing Bus

B8-54 Fajiure of Circuit Breaker 7/28/68 All holders of OLs

Following Installation of or CPs for nuclear

Amptector Direct Trip power reactors.

Attactrent

88-S- Licensee Violations of NRC 7/28es All manufacturers and

Reculations. Whicn Leo to distributcrs of radio- leoical Diagnostic ptarraceuticals for

misaoministrations huran use. nucledr

pharracies. ano

necical licensees.

OL

• Doeratino License

-T

CP

• Ccnstructicr. Permit

UNITED STATES FIRST CLASS MAIL

NUCLEAR REGULATORY COMMISSION POSTAGE & FEES PAID

WASHINGTON, D.C. 20555 USNAC

P£RMIT Ne. S67 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. $300

IN 88-61 August 11, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge, NRR

(301) 492-1169 Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Figure 1. Schematic Air Flow Path Diagram of Essential Control Room

Heating, Ventilating, and Air Conditioning System (ECR HVAC) at Vogtle.

Assumed Containment Isolation Signal for Unit 1 with Train B Failed.

2. List of Information Notices Related to Control Room Habitability Systems

3. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

• C/OGCB:DOEA:NRR *PPMB:ARM

CHBerlinger TechEd

08/G /88 05/31/88 04/05/88

• OGCB:DOEA:NRR *SPLB:DEST: NRR *A C SPLB:DEST:NRR *SAD/DEST:NRR *D/DEST:NRR

CVHodge CRNichols JWCraig AThadani LCShao

03/31/88 03/31/88 05/06/88 05/13/88 05/16/88

IN 88-XX

May xx, 1988 habitability systems at 12 operating plants. Numerous types of discrepancies

are described involving differences between (1) the design, construction, operation and/or testing of these systems and (2) corresponding technical

specifications when compared with the descriptions and analyses provided in

licensing basis documents, Including assumptions in the toxic gas and radiation

dose calculations.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contacts listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge, NRR

(301) 492-1169 Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Summaries of Recent Reports Concerning Control Room Habitability

2. Figure 1. Schematic Flow Path Diagram of Essential Control Room Heating, Ventilating, and Air Conditioning System at Vogtle 1 and 2

3. List of References

4. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

D/DOEA:NRR

C¢6 C/OGCB:DOEA:NRR *PPMB:ARM

CERoss i CHBerl inger TechEd

05/ /88 O/n-/88 04/05/88

• OGCB:DOEA:NRR *SPLB:DEST:NRR *A/C/SPLB:DEST:NRR SAD/DEST:NyJSp D/DEST:N/I

CVHodge CRNichols JWCrai g AThadani Al LCShao

03/31/88 03/31/88 05/06/88 0 5 /y 8 8 05//88 A

IN 88-XX

May xx, 1988 control room habitability systems at 12 operating plants. Numerous types of

discrepancies are described between the design, construction, operation and

testing of these systems and corresponding technical specifications compared

with the descriptions and analyses provided in licensing basis documents, including assumptions in the toxic gas and radiation dose calculations. The

NRC plans to distribute the report to all holders of operating licenses or

construction permits for nuclear power reactors.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contacts listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge, NRR

(301) 492-1169 Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Summaries of Recent Reports Concerning Control Room Habitability

2. Figure 1. Schematic Flow Path Diagram of Essential Control Room Heating, Ventilating, and Air Conditioning System at Vogtle 1 and 2

3. List of References

4. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

D/DOEA:NRR C/OGCB:DOEA:NRR *PPMB:ARM

CERoss i CHBerlinger TechEd

5/ /88 05/ /88 04/05/88

• OGCB:DOEA:NRR *SPLB:DEST:NRR , /8PLB:DEST:NRR SAD/DEST:NRR D/DEST:NRR

CVHodge CRNichols {Craig AThadani LCShao

03/31/88 03/31/88 05/ /88 05/ /88

IN 88-XX

March xx, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact below or the Regional Administrator of the appropriate regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge

(301) 492-1169 Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Summaries of Recent Events Concerning Control Room Habitability

2. Figure 1. Schematic Flow Diagram of Control Room Essential Heating, Ventilating and Air Conditioning System at Vogtle 1 and 2

3. List of References

4. List of Recently Issued NRC Information Notices

D/DOEA:NRR C/OGCB:DOEA:NRR PPMB:ARM

CERossi CHBerlinger TechEd

03/ /88 03/ /88 03/ /88 OGCB:DOEA:NRR SPLB:DEST:NRR A/C/SPLB:DEST:NRR SAD/DEST:NRR D/DEST:NRR

CVHodge CRNichols JWCraig AThadani LCShao

03/31/88 034X /88 03/ /88 03/ /88 03/ /88