Information Notice 1986-76, Problems Noted in Control Room Emergency Ventilation Systems

Problems Noted in Control Room Emergency Ventilation Systems

ML031250186
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, 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, Skagit, Marble Hill, Crane
Issue date:	08/28/1986
From:	Jordan E NRC/IE
To:
References
IN-86-076, NUDOCS 8608250306
Download: ML031250186 (5)

L's 6SSINS

No.: 6835 IN 86-76

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C.

20555

August 28, 1986

IE INFORMATION NOTICE NO. 86-76: PROBLEMS NOTED IN CONTROL ROOM

Addressees

All nuclear power reactor facilities holding an operating license or a con- struction permit.

Purpose

This notice is provided to alert recipients to problems noted in the operation

of control 'room emergency ventilation systems during recent plant visits by an

NRC review team.

It is expected that recipients will review this information

for applicability to their facilities and consider actions, if appropriate, to

preclude a similar problem occurring at their facilities.

However, suggestions

contained in this notice do not constitute NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

During a recent visit to the Trojan Nuclear Plant, the NRC review team observed

the licensee perform a monthly surveillance test of the cooling capability of

the control room emergency ventilation system.

The NRC review team terminated

its involvement shortly after the surveillance test began because the

licensee's procedure was deemed inadequate and the test would not produce any

meaningful results.

Specifically, the team noted that the emergency ventila- tion system was initiated with the supply dampers left shut; these dampers were

designed to provide 150 standard cubic feet per minute (cfm) of outside makeup

air in the radiological emergency mode. The toilet and laboratory exhaust fans

(4050 and 3740 cfm capacity, respectively) were left running. This condition

resulted in a slight vacuum in the control room, although the system is

designed to maintain 1/8-inch H20 positive pressure in the emergency mode.

In

addition, the humidity control had been adjusted to 100 percent (thus the

heaters would remain off for any humidity less than 100 percent) even though

the Technical Specifications require the system to be tested with the heaters

on.

When the makeup air dampers were opened, it was determined that 460 cfm of

filtered outside air was being supplied instead of the designed 150 cfm. *In

addition, it was discovered that a 2-inch drain pipe on the cooling units down

stream of the filter housing was drawing 41 cfm of unfiltered outside air into

the system.

The drain pipe was connected by a drain line header to both trains

8608250306

IN 86-76 August 28, 1986 of the emergency ventilation systems.

This drain arrangement constituted a

common-mode failure and a lack of train separation of an engineered safety

feature.

On the basis of these findings, Region V inspectors asked Trojan to

recalculate the operator doses expected during an accident.

The licensee

calculated 1.7 rem whole body, 195 rem to the thyroid, and 30.6 rem to the

skin.

The general design criteria (GDC 19) in Appendix A of 10 CFR Part 50

specifies that the control room be designed to allow occupancy through the

course of an accident without exceeding 5 rem whole body or its equivalent to

any part of the body.

Because 30 rem to any organ (skin or thyroid) is equiva- lent to a 5 rem whole-body dose, a violation resulted. The violation was

categorized as a Severity Level II violation because both trains of the system

were inoperable for a long period of time and a civil penalty resulted.

The NRC has made several plant visits to review control room ventilation

systems as part of the resolution of the generic issue on control room habit- ability (Item III D.3.4 of NUREG-0737).

Although Trojan has been the only

plant visit to date with problems severe enough to result in an enforcement

action, several similar problems have been noted at other facilities visited.

Attachment 1 provides a discussion of these common problems noted.

Currently

the NRC is scheduled to visit six more facilities in response to the generic

issue.

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

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

Administrator of the appropriate regional office or this office.

Edwarcvi Jordan, Director

Divis ph of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts: Roger L. Pedersen, IE

(301)492-9061

John J. Hayes, NRR

(301)492-7471 Attachments:

1. Summary of Control Room Habitability Reviews

2. List of Recently Issued IE Information Notices

Attachment 1

IN 86-76 August 28, 1986 SUMMARY OF CONTROL ROOM HABITABILITY REVIEWS

The following is a summary of the common problems noted in control room emer- gency ventilation systems during recent NRC plant visits to gather information

on Control Room Habitability (Generic Issue 83). Items discussed were noted at

two or more facilities visited.

System Understanding- The NRC review team noted that there appeared to be no individual or group

designated as responsible for the ventilation systems at the plant visited.

This appears to lead to a lack of understanding of the systems and their

operation. Most of the systems reviewed to date do not accurately reflect the

system descriptions provided by the licensees in their submittals required by

item III 0.3.4 of TMI Action Plan (NUREG-0737). In addition, the following

concerns were noted in the way surveillance testing is being performed on these

systems.

1. Most plants measured control room temperature in the center of the room.

However, the basis of the requirement is to ensure operability of

solid-state electrical equipment, not operator comfort.

Therefore, measuring the air temperature at the instrument panels is more appropriate

(see IE IN 85-89 for additional information on the effects of control room

cooling on solid-state instrumentation).

2. The purpose of maintaining a positive pressure in the control room during

emergency operation is to ensure any leakage is out of (rather than into)

the control room.

Several licensees show compliance with their technical

specifications by comparing control room pressure to the outside atmo- spheric pressure. Because areas adjacent to the control room envelope

(CRE)

can be at higher-than-atmospheric pressure, a relative negative

control room pressure may exist across the CRE boundary, providing a

motive force for inleakage.

This is also a concern where the control room

ventilation system is routed through adjacent areas.

Clearly it is

appropriate to measure the differential pressure relative to the highest

pressure adjacent to the CRE boundary or ventilation system.

3. Laboratory testing of charcoal efficiency is being performed at tempera- tures much higher than any temperature expected during the course of an

accident. This can result in an erroneously high efficiency measurements.

Retention efficiencies as low as 70% were noted when samples of charcoal

that had just passed its surveillance tests (greater than 90% efficient)

were retested at 30'C.

Attachment 1

IN 86-76

August 28, 1986 Excessive Unfiltered Inleakage

The general condition of some of the ventilation systems reviewed was poor.

Many of the following conditions were discovered that resulted in leakage of

unfiltered air into the systems reviewed.

1. Holes and openings: Many holes left from construction and unplugged

openings were found in the system duct work and in the air handling units

themselves.

2. Drains: Uncapped drains (or drains improperly left open to the atmosphere)

were found that allow the air handling units to draw air into the system.

In addition, water loop seals in some drains were found dry.

3. CRE penetrations:

Some control rooms were found with "numerous" unsealed

penetrations across the CRE.

Many of these problems were not discovered until the NRC review team performed

flow balance and differential pressure measurements on the control room venti- lation systems.

I

Attachment 2

IN 86-76

August 28, 1986

LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issue

Issued to

86-75

86-74

86-73

86-72

86-71

86-70

86-69

86-68

86-67

86-66

Incorrect Maintenance

Procedure On Traversing

Incore Probe Lines

8/21/86 Reduction Of Reactor Coolant 8/20/86 Inventory Because Of Misalign- ment Of RHR Valves

Recent Emergency Diesel

8/20/86

,Generator Problems

Failure 17-7 PH Stainless

8/19/86

Steel Springs In Valcor

Valves Due to Hydrogen

Embrittlement

Recent Identified Problems

8/19/86

With Limitorque Motor

Operators

Spurious System Isolation

8/18/86

Caused By The Panalarm Model

86 Thermocouple Monitor

Scram Solenoid Pilot Valve

8/18/86 (SSPV) Rebuild Kit Problems

Stuck Control Rod

8/15/86 Portable Moisture/Density

8/15/86 Gauges: Recent Incidents And

Common Violations Of Require- ments For Use, Transportation, And Storage

x

Potential For Failure Of

8/15/86

Replacement AC Coils Supplied

By The Westinghouse Electric

Corporation For Use In Class

1E Motor Starters And

Contractors

All power reactor

facilities holding

an OL or CP

All BWR facilities

holding an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All GE BWR facilities

holding an OL or CP

All BWR facilities

holding an OL or CP

All BWR

holding

facilities

an OL or CP

All NRC licensees

authorized to possess, use, transport, and

store sealed sources

All power reactor

facilities holding

an OL or CP

OL = Operating License

CP = Construction Permit