ML18102B649

Proposed Tech Specs Pages,Modifying TS 3/4.7.7, Auxiliary Building Exhaust Air Filtration Sys & Bases

ML18102B649
Person / Time
Site:	Salem
Issue date:	10/24/1997
From:	Public Service Enterprise Group
To:
Shared Package
ML18102B648	List: ML18102B647 ML18102B649
References
NUDOCS 9711050234
Download: ML18102B649 (19)

Text

PLANT SYSTEMS 3/4.7.7 AUXILIARY BUILDING EXHAUST AIR FILTRATION SYSTEM LIMITING CONDITION FOR OPERATION APPLICABILITY: MODES 1, 2, 3 and 4.

ACTION:

SURVEILLANCE REQUIREMENTS 9711050234 971024 PDR ADOCK 05000272 P PDR SALEM - UNIT 1 3/4 7-22 Amendment No. 3

PLANT SYSTEMS SURVEILLANCE RE UIREMENTS Continued I1 during

c. ~fter every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of clia1 ceal adsor be1 operatier:i by eitA@.F.i ~

C. !rJ'>tfL\

SALEM-UNIT l 3/4 7-23 Amendment No.

• 3

PLANT SYSTEMS SURVEILLANCE RE UIREMENTS Continued

~

.*a:,

SALEM-UNIT l 3/4 7-24 Amendment No. 3

PLANT SYSTEMS SURVEILLANCE REQUIREMENiS (Continued) 1-

. :. l .

- . I

.II 1.

D lo1J'T 1

D SALEM-UN IT l 3/4 7-25 Amendment No. 3

PLANT SYSTEMS BASES

===========================c==============================

The OPERABILITY of this system in conjunction with control room design provisions is based on limiting the radiation exposure to personnel occupying the control room to 5 rem or less whole body, or its equivalent. This limitation is consistent with the requirements of General Design Criterion 19 of Appendix "A", 10 CFR 50.

3/4.7.B SEALED SOURCE CONTAMINATION The limitations on removable contamination for sources requiring leak testing, including alpha emitters, is based on 10 CFR 70.39(c) limits for plutonium. This limitation will ensure that leakage from byproduct, source, and special nuclear material sources will not exceed allowable intake values.

SALEM - UNIT 1 B 3/4 7-Sc Amendment No .190

?LANT SYSTEMS 3/ 4. 7. 7 .Z'..UXILIJl.RY BUILDING EXP.AUST JI.IR FILTRATION SYSTE'.-1 LIMITING CONDITION FOR OPERATION APPLICABILITY: MODES 1, 2, 3 and 4.

s:

l~>-zr-.-f'"'iiTtF"e~ t rain in ope r ab l e , r*f!°Sn-rN'o<'io...-4:JJ us wit'in 24 h SURVEILLANCE REQUIREMENTS I

Y

. .* I

~,.------

Buildi exhaus air filtration system I I I

rom the control room, I rber t in and erify" t leas 15 mi utes.

• mai tenance

\

)>,

er hous'ngs, or (2) f llowing )

any v ntilati n zon, commq.Q_V SALEM - UNIT 2 3/4 7-18

PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

==================================================================

the system starts on a Safety Injection SALEM - UNIT 2 3/4 7-19 Amendment No. 168

PLANT SY STEMS SURVEILLANCE REQUIREMENTS (Continued)

SALEM - UNIT 2 3/4 7-20

PLANT SYSTEMS BASES

==================================================================

The OPERABILITY of this system in conjunction with control room design provisions is based on limiting the radiation exposure to personnel occupying the control room to 5 rem or less whole body, or its equivalent. This limitation is consistent with the requirements of General Design Criterion 19 of Appendix "A", 10 CFR Part 50.

3/4.7.7 AUXILIARY BUILDING EXHAUST AIR FILTRATION SYSTEM 3/4.7.8 SEALED SOURCE CONTAMINATION The limitations on removable contamination for sources requiring leak testing, including alpha emitters, is based on 10 CFR 70.39(c) limits for plutonium. This limitation will ensure that leakage from byproduct, source, and special nuclear material sources will not exceed allowable intake values.

Sealed'sources are classified into three groups according to their use, with surveillance requirements commensurate with the probability of damage to a source in that group. Those sources which are frequently handled are required to be tested more often than those which are not. Sealed sources which are continuously enclosed withi~ a shielded mechanism (i.e., sealed sources within radiation monitoring or boron measuring devices) are considered to be stored and need not be tested unless they are removed from the shielded mechanism.

SALEM - UNIT 2 B 3/4 7-5c Amendment No.173

ATTACHMENT 3 SALEM GENERATING STATION UNITS 1 AND 2 FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 DOCKET NOS. 50-272 AND 50-311 AUXILIARY BUILDING VENTILATION SYSTEM (ABVS)

TECHNICAL SPECIFICATION PAGES WITH PROPOSED CHANGES The following Technical Specifications for Facility Operating License Nos. DPR-70 and DPR-75 are affected by this change request:

Unit 1 Technical Specification Pages 3/4.7.7 3/4 7-22 to 3/4 7-25 B3/4.7.7 B 3/4 7-5c Unit 2 Technical Specification Pages 3/4.7.7 3/4 7-18 to 3/4 7-20 B3/4.7.7 B 3/4 7-5c

Document Control Desk LR-N97488 LCR S95-44 Insert A Three Auxiliary Building exhaust air HEPA filter trains, one carbon adsorber bank, two supply fans, and three exhaust fans, shall be OPERABLE.

Auxiliary Building pressure shall be negative with respect to atmospheric pressure.

Insert 8

a. With one HEPA filter train inoperable, restore the inoperable HEPA filter train to OPERABLE status within 7 days or be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

b. With no HEPA train associated with the one Carbon Adsorber operable, restore at least one associated HEPA train to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STAND-BY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c. With the carbon adsorber inoperable, restore the carbon adsorber to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

d. With one supply fan or one exhaust fan inoperable, restore the fan to OPERABLE status within 14 days or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

e. With Auxiliary Building pressure at or above zero inches water column (O.OO"wc) with respect to atmospheric pressure, restore building negative pressure within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

f. With less than two exhaust fans operable restore one exhaust fan to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

g. With no supply fans operable, be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Document Control Desk LR-N97488 LCR S95-44 Insert C The Auxiliary Building Exhaust air filtration system shall be demonstrated OPERABLE:

a. At least once each 31 days by aligning to the ECCS flow path and initiating flow for at least 15 minutes (for each train) through:

1. filter train 11 and carbon adsorber train 14, then

2. filter train 12 and carbon adsorber train 14

b. At least once each 18 months, or (1) following painting, fire or chemical release in any ventilation zone communicating with the system, or (2) any partial or complete replacement of the HEPA or carbon filters, by:

1. Verifying that, with the ECCS duct flow path and HEPA train 11 aligned to carbon adsorber train 14 and operating at a flow rate of 21,400 CFM +/-10%,

the total bypass flow is less than or equal to 1%

when tested by injecting halogenated hydrocarbon refrigerant.

2. Verifying that, with the ECCS duct flow path and HEPA train 12 aligned to carbon adsorber train 14 and operating at a flow rate of 21,400 CFM +/-10%,

the total bypass flow is less than or equal to 1%

when tested by injecting halogenated hydrocarbon refrigerant.

3. Verifying that, in-place leak testing of the carbon adsorber train 14 removes ~99% of a halogenated hydrocarbon refrigerant test gas when tested at 21,400 CFM +/-10% in accordance with Regulatory Guide 1.52 Rev 2, 1978, Section C.5.d.

4. Verifying that, in-place leak testing of HEPA filter banks in trains 11,12,13 will remove 99% of DOP when tested at their rated design flow capacity +/-10% for each housing in accordance with Regulatory Guide 1.52 Rev 2, 1978, Section C.5.c.

5. Verifying within 31 days after removal that laboratory analysis of a representative carbon

Document Control Desk LR-N97488 LCR S95-44 sample demonstrates a removal of ~90% elemental iodine when tested in accordance with ANSI D3803 Revision 1989.

6. Verifying that flow rate through the carbon adsorber does not exceed 23,540 cfm (21,400 + 10%)

when either HEPA + carbon adsorber combination is aligned to the ECCS areas.

7.a. Verifying the total pressure drop across HEPA train 11 and carbon adsorber train 14 is :S:4" Water Gauge when tested at 21,400 CFM +/-10%.

7.b. Verifying the total pressure drop across HEPA train 12 and carbon adsorber train 14 is :S:4" Water Gauge when tested at 21,400 CFM +/-10%.

8. Verifying that, with HEPA train 11 aligned to the carbon adsorber 14 and HEPA train 12 aligned to the normal area duct, the system can maintain the Auxiliary Building at a slight negative pressure with respect to outside ambient pressure.

Insert D

c. After every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation verify that within 31 days after removal that laboratory analysis of a representative carbon sample demonstrates a removal of ~90% elemental iodine when tested in accordance with ANSI D3803 Revision 1989.

d. After maintenance affecting the flow distribution, verify that the airflow distribution of the system is acceptable when tested in accordance with Regulatory Guide 1.52, Revision 2, 1978 Section C.5.b.

e. After any structural maintenance on the HEPA or carbon adsorber unit mounting frames or housing, perform tests as required by surveillance 4.7.7.1.b.3 and 4.7.7.1.b.4.

f. After operation of Auxiliary Building normal flow path through the carbon adsorber, prior to mode 4 entry, verify the carbon adsorber will remove ~99%

Document Control Desk

• LR-N97488 LCR S95-44 of a halogenated hydrocarbon refrigerant test gas when in-place leak tested at a flow rate of 21,400 CFM +/-10%.

g. After operation of containment purge exhaust flow path through the carbon adsorbers, prior to mode 4 entry, verify the carbon adsorbers will remove

~99% of a halogenated hydrocarbon refrigerant test gas when in-place leak tested at a flow rate of 21,400 CFM +/-10%.

Insert E Three Auxiliary Building exhaust air HEPA filter trains, one carbon adsorber bank, two supply fans, and three exhaust fa~s, shall be OPERABLE.

Auxiliary Building pressure shall be negative with respect to atmospheric pressure.

Insert F

a. With one HEPA filter train inoperable, restore the inoperable HEPA filter train to OPERABLE status within 7 days or be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

b. With no HEPA train associated with the one Carbon Adsorber operable, restore at least one associated HEPA train to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STAND-BY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c. With the carbon adsorber inoperable, restore the carbon adsorber to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

d. With one supply fan or one exhaust fan inoperable, restore the fan to OPERABLE status within 14 days or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

e. With Auxiliary Building pressure at or above zero inches water column (O.OO"wc) with respect to atmospheric pressure, restore building negative pressure within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in

Document Control Desk LR-N97488 LCR S95-44 HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

f. With less than two exhaust fans operable restore one exhaust fan to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

g. With no supply fans operable, be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Insert H The Auxiliary Building Exhaust air filtration system shall be demonstrated OPERABLE:

a. At least once each 31 days by aligning to the ECCS flow path and initiating flow for at least 15 minutes (for each train) through:

1. filter train 21 and carbon adsorber train 24, then

2. filter train 22 and carbon adsorber train 24

b. At least once each 18 months, or (1) following painting, fire or chemical release in any ventilation zone communicating with the system, or (2) any partial or complete replacement of the HEPA or carbon filters, by:

1. Verifying that, with the ECCS duct flow path and HEPA train 21 aligned to carbon adsorber train 24 and operating at a flow rate of 21,400 CFM +/-10%,

the total bypass flow is less than or equal to 1%

when tested by injecting halogenated hydrocarbon refrigerant.

2. Verifying that, with the ECCS duct flow path and HEPA train 22 aligned to carbon adsorber train 24 and operating at a flow rate of 21,400 CFM +/-10%,

the total bypass flow is less than or equal to 1%

when tested by injecting halogenated hydrocarbon refrigerant.

3. Verifying that, in-place leak testing of the carbon adsorber train 24 removes ~99% of a

Document Control Desk

• LR-N97488 LCR S95-44 halogenated hydrocarbon refrigerant test gas when tested at 21,400 CEM +/-10% in accordance with Regulatory Guide 1.52 Rev 2, 1978, Section C.5.d.

4. Verifying that, in-place leak testing of HEPA filter banks in trains 21,22,23 will remove 99% of DOP when tested at their rated design flow capacity +/-10% for each housing in accordance with Regulatory Guide 1.52 Rev 2, 1978, Section C.5.c.

5. Verifying within 31 days after removal that laboratory analysis of a representative carbon sample demonstrates a removal of ~90% elemental iodine when tested in accordance with ANSI D3803 Revision 1989.

6. Verifying that flow rate through the carbon adsorber does not exceed 23,540 cfm (21,400 + 10%)

when either HEPA + carbon adsorber combination is aligned to the ECCS areas.

7.a. Verifying the total pressure drop across HEPA train 21 and carbon adsorber train 24 is ~4" Water Gauge when tested at 21,400 CEM +/-10%.

7.b. Verifying the total pressure drop across HEPA train 22 and carbon adsorber train 24 is ~4" Water Gauge when tested at 21,400 CEM +/-10%.

8. Verifying that, with HEPA train 21 aligned to the carbon adsorber 24 and HEPA train 22 aligned to the normal area duct, the system can maintain the Auxiliary Building at a slight negative pressure with respect to outside ambient pressure.

Insert I

c. After every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation verify that within 31 days after removal that laboratory analysis of a representative carbon sample demonstrates a removal of ~90%

elemental iodine when tested in accordance with ANSI D3803 Revision 1989.

d. After maintenance affecting the flow distribution, verify that the airflow distribution of the system is acceptable

Document Control Desk

• LR-N97488 LCR S95-44 when tested in accordance with Regulatory Guide 1.52, Revision 2, 1978 Section C.5.b.

e. After any structural maintenance on the HEPA or carbon adsorber unit mounting frames or housing, perform tests as required by surveillance 4.7.7.1.b.3 and 4.7.7.1.b.4.

f. After operation of Auxiliary Building normal flow path through the carbon adsorber, prior to mode 4 entry, verify the carbon adsorber will remove ~99% of a halogenated hydrocarbon refrigerant test gas when in-place leak tested at a flow rate of 21,400 CEM +/-10%.

g. After operation of co,ntainment purge exhaust flow path through the carbon adsorbers, prior to mode 4 entry, verify the carbon adsorbers will remove ~99% of a halogenated hydrocarbon refrigerant test gas when in-place leak tested at a flow rate of 21,400 CEM +/-10%.

Insert J The Auxiliary Building Ventilation System (ABVS) consists of two major subsystems. They are designed to control Auxiliary Building temperature during normal and emergency modes of operation, and to contain Auxiliary Building airborne contamination during Loss of Coolant Accidents (LOCA). The two subsystems are:

1. A once through filtration exhaust system, designed to contain particulate and gaseous contamination and prevent it from being released from the building in accordance with 10CFR20, and

2. A once through air supply system, designed to deliver outside air into the building to maintain building temperatures within acceptable limits. For the purposes of satisfying the Technical Specification LCO, one supply fah must be administratively removed from service such that the fan will not auto-start on an actuation signal; however, the supply fan must be OPERABLE with the exception of this administrative control.

These systems operate during normal and emergency plant modes.

Additionally, the system provides a flow path for containment purge supply and exhaust during Modes 5 and 6.

The exhaust system consists of three 50% capacity fans that are powered from vital buses. These fans exhaust from a common plenum

Document Control Desk

• LR-N97488 LCR S95-44 downstream from three High Efficiency Particulate Air (HEPA) filter banks, two of which, 11/21 & 12/22 can be interchangeably aligned to discharge to a single carbon adsorber bed. Filter unit 11/21 is limited in capacity and can only be aligned to the ECCS areas of the Auxiliary Building for HEPA only or HEPA + Carbon modes of filtration. Filter unit 12/22 can be used to ventilate the normal areas of the Auxiliary Building in HEPA only, or when used in conjunction with 13/23, may be used to ventilate the ECCS areas of the Auxiliary Building in HEPA + Carbon. Filter unit 13/23 does not communicate with the carbon adsorber housing and is used for exhausting air from the normal areas of the Auxiliary Building during any plant Mode or purging the Containment Building during Modes 5&6. The fans are designed for continuous operation, to control the Auxiliary Building pressure at -0.10" Water Gauge with respect to atmosphere.

The supply system consists of two 100% capacity fans that are powered from vital buses, and distribute outdoor air to the general areas and corridors of the building through associated ductwork.

AUXILIARY BUILDING VENTILATION ALIGNMENT MATRIX NORMAL VENTILATION (Normal plant operations)*

Unit 11(21) from ECCS HEPA only, with Unit 12(22) from Aux. Normal HEPA only; or Unit 11(21) from ECCS HEPA only, with Unit 13(23) from Aux. Normal HEPA only; or Unit 12(22) from ECCS HEPA only, with Unit 13(23) from Aux. Normal HEPA only; and Any two of the three exhaust fans; and Either of the two supply fans.

• The normal alignment is two exhaust fans and one supply fan.

During cooler seasons, and with the absence of the system heating coils, it may be required to limit the amount of colder outside air entering the building. In this case, it is acceptable to secure both supply fans from operation and reduce the number of operating exhaust fans to one. There is sufficient capacity with the single exhaust fan to maintain the negative pressure within the auxiliary building boundary.

Document Control Desk LR-N97488 LCR S95-44 EMERGENCY VENTILATION (Emergency plant operations)

Unit 11 (21) from ECCS HEPA + Unit 14(24), with Unit 12(22) from Aux. Normal HEPA only; or Unit 11 (21) from ECCS HEPA + Unit 14(24), with Unit 13(23) from Aux. Normal HEPA only; or Unit 12(22) from ECCS HEPA + Unit 14(24), with Unit 13(23) from Aux. Normal HEPA only; and At least two of the three exhaust fans; and Either one of the two supply fans.

Note: During a Safety Injection (SI) all three exhaust fans and one of the supply fans will start. This is acceptable and will maintain the boundary pressure while supplying the required cooling to the building.

Should access/egress become difficult with the three exhaust fans running, then one of the exhaust fans should be secured.

OPERABILITY of the Auxiliary Building exhaust air filtration system ensures that air, which may contain radioactive materials leaked from ECCS equipment following a LOCA, is filtered and monitored prior to release from the plant. Operation of this system and the resultant effect on off site dosage calculations was assumed in the accident analyses. ABVS is discussed in Updated Final Safety Analysis Report (UFSAR) Section 9.4.2.

ANSI N510-1975, ANSI D3803-89, and Generic Letter 83-13 are to be used to develop criteria for surveillance testing.

During modes 5 and 6, following normal plant shutdown, it is permissible to route Auxiliary Building normal ventilation or containment purge exhaust through the carbon adsorber filters; however, due to excess flows inherent in this practice, it will be necessary to perform the in-place leak test to verify carbon bed integrity/operability prior to re-entering mode 4.