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 atmosphere.

During construction, the Unit 2 duct opening had been isolated by locking the dampers closed. If one of the outside air isolation

dampers for 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 gases was no longer needed. Thus, the licensee deactivated

and tagged open the 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

power as required.

These timers are designed to actuate banks of compressed

air to 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

I IN 88-61 August 11, 1988 test procedure.

This action was effective

in increasing

control room pressure to meet the technical

specification

requirement.

The licensee installed

sealing tape around the seven doors and established

a preventive

maintenance

program to inspect the seals on all control room doors every 6 months for a 1-year period.The licensee plans to determine

an appropriate

frequency

for preventive

mainte-nance of the door seals. The surveillance

test of the control area ventilation

and chilled water system will also be repeated every 6 months until sufficient

information

is obtained for determining

an appropriate

frequency.

Farley 1: On June 5, 1987, the licensee discovered

that none of four fire dampers in the control room ventilation

system would fully 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

revealed that the dampers would not have received an actuation

signal from a Firestat set to sense 160 0 F in the control room ceiling because of installation

errors. The licensee at-tributed the problems to three causes: a design deficiency

pertaining

to the full closure and latching of the dampers, inadequate

testing of the actuation circuitry, and inadequate

preventive

maintenance

of the dampers.Discussion:

In addition to the above, the NRC has recently completed

an engineering

evalu-ation, "Design and Operating

Deficiencies

in Control Room Emergency

Ventilation

Systems," AEOD/E802, April 1988 based on recent events that highlight

single failure vulnerabilities

in control room emergency

ventilation

systems.*

The NRC also has recently conducted

a survey of control room habitability

systems at 12 operating

plants. Numerous discrepancies

were found between the analyzed and actual performance

of these systems. For example, differences

exist between design, construction, operation, and/or testing of these systems and the de-scriptions

and analyses provided in licensing

documents, as for example in the assumptions

used in the toxic gas and radiation

dose calculations.

In addition, analyses assumptions

have not always been consistent

with technical

specifi-cation requirements.

The NRC has issued several information

notices related to this subject (see Attachment

'2). Resolution

of Generic Issue 83: Control Room Habitability

is also ongoing.*A copy of the report is available

in the NRC Public Document Room, 1717 h Street, N.W., Washington, D.C. 20555, for inspection

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 L , AIR OUTSIDE;AIR% v vv OUTSIDE AIR SUPPLY DUCT ((cn c LA CO 0~FIGURE 1. SCHEMATIC

AIR FLOW PATH DIAGRAM OF ESSENTIAL

CONTROL ROOM HEATING, VENTILATING, AND 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.86-76 85-89 83-62 TITLE DATE Problems Noted in Control Room Emergency

Ventilation

Systems Potential

Loss of Solid-State

Instrumentation

Following

Failure of Control Room Cooling Failure of Redundant

and Toxic Gas Detectors

Positioned

at Control Room Ventilation

Air Intakes August 28, 1986 November 19, 1985 September

26, 1983

'- .dachment

3 IN 88-61 August 11. 4988 Page I of I LIST OF RECENtLY ISSUED NRC INFORMIATION

NOTICES InfTornation

Notice No. Subject 88-60 Inadeouste

Design and Installation

of Watertight

Penetration

Seals B8-04. Inadecuate

Qualifitation

Supplerent

I and Documentation

of Fire Barrier Penetration

Seals 88-59 Kain Steam Isolation

Valve Guide Rail Failure at Waterford

Unit 3 88-58 88-57 88-56 88-55 B8-54 88-S-Potential

Probiems with ASEA Brown Boveri TE-S1L Time-COercurrent

Pelays Potential

Loss of Safe Shutccwn Eoulprent

Due to Premature

Siliccr Controllee

Rectifier

Failure Potential

Prcblems wtth Siliccre Foam Fire Barrier Penetration

Seals Potential

Problems Caused by Sirgle Failure of an Engineered

Safety Feature Swing Bus Fajiure of Circuit Breaker Following

Installation

of Amptector

Direct Trip Attactrent

Licensee Violations

of NRC Reculations.

Whicn Leo to leoical Diagnostic

misaoministrations

Date of Issuance S/11B8 8/9/88 819/88 8/8/E8 8/8/88 8/4/88 8/3/18 7/28/68 7/28es Issued to All holders of OLs or CPs for nuclear power reactors.All holders of MLs or CPs for nuclear power reactors.All holders of OLs or CFs for nuclear power reactors.All holders of OLs or CPs 'or nuclear power oeactors.All holders of QLs or CFs for nuclear power reactors.All holders of OLs or CFs 'or nuclear power reactors.All holders of CIs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All manufacturers

and distributcrs

of radio-ptarraceuticals

for huran use. nucledr pharracies.

ano necical licensees.-T OL

• Doeratino

License CP

• Ccnstructicr.

Permit UNITED STATES NUCLEAR REGULATORY

COMMISSION

WASHINGTON, D.C. 20555 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. $300 FIRST CLASS MAIL POSTAGE & FEES PAID USNAC P£RMIT Ne. S67 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

08/G /88 NRR *A C SPLB:DEST:NRR

JWCraig 05/06/88*C/OGCB:DOEA:NRR

CHBerlinger

05/31/88*SAD/DEST:NRR

AThadani 05/13/88*PPMB:ARM TechEd 04/05/88*D/DEST:NRR

LCShao 05/16/88*OGCB:DOEA:NRR

CVHodge 03/31/88*SPLB:DEST:

CRNichols 03/31/88 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

• OGCB:DOEA:NRR

CVHodge 03/31/88*SPLB:DEST:NRR

CRNichols 03/31/88 D/DOEA:NRR

CERoss i 05/ /88*A/C/SPLB:DEST:NRR

JWCrai g 05/06/88 C¢6 C/OGCB:DOEA:NRR

CHBerl inger O/n-/88 SAD/DEST:NyJSp

AThadani Al 0 5/y 8 8*PPMB:ARM TechEd 04/05/88 D/DEST:N/I

LCShao 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

• OGCB:DOEA:NRR

CVHodge 03/31/88 D/DOEA:NRR

CERoss i 5/ /88*SPLB:DEST:NRR , /8PLB:DEST:NRR

CRNichols

{Craig 03/31/88 C/OGCB:DOEA:NRR

CHBerlinger

05/ /88 SAD/DEST:NRR

AThadani 05/ /88*PPMB:ARM TechEd 04/05/88 D/DEST:NRR

LCShao 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 OGCB:DOEA:NRR

CVHodge 03/31/88 D/DOEA:NRR

CERossi 03/ /88 A/C/SPLB:DEST:NRR

JWCraig 03/ /88 C/OGCB:DOEA:NRR

CHBerlinger

03/ /88 SAD/DEST:NRR

AThadani 03/ /88 SPLB:DEST:NRR

CRNichols 034X /88 PPMB:ARM TechEd 03/ /88 D/DEST:NRR

LCShao 03/ /88