ML18153C135

Proposed Tech Specs Eliminating Monthly Flush Requirements for Sensitized Stainless Steel Piping Installed in Primary & Safety Sys

ML18153C135
Person / Time
Site:	Surry
Issue date:	03/08/1990
From:	FLORIDA POWER CORP.
To:
Shared Package
ML18153C134	List: ML18153C133 ML18153C135
References
NUDOCS 9003160018
Download: ML18153C135 (12)

Text

ATTACHMENT I Proposed Technical Specifications Change

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TS 4.1-la

3. The pressurizer water volume shall be determined to be within its limit as defined in Specification 2.3.A.3.a at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> whenever the reactor is not subcrit i cal by at least 1% t.k/k.

4. Each Reactor Vessel Head vent path isolation valve not required to be closed by Specification 3.1.A.7a or 3.1.A.7b shall be demonstrated operable at each cold shutdown but not more often than once per 92 days by operating the valve through one complete cycle of full travel from the control room.

5. Each Reactor Vessel Head vent path shall be demonstrated operable following each refueling by:

a. Verifying that the upstream manual isolation valve in each vent path is locked in the open position.

b. Cycling each isolation valve through at least one complete cycle of full travel from the control room.

c. Verifying flow through the reactor vessel head vent system vent paths.

C. Sampling tests shall be conducted as detailed in Table 4.1-28.

D. Whenever containment integrity is not required, only the asterisked items in Table 4.1-1 and 4.1-2A and 4.1-28 are applicable.

E. Flushing of wetted sensitized stainless steel pipe sections as identified in the Basis Section shall be conducted only if the RWST Water Chemistry exceeds O.15 PPM chlorides and/or fluorides (Cl and/or F-). Flushing shall be conducted as detailed in TS Table 4.l-3A and 4.1-38.

TS 4.1-2 H. If the RWST Water Chemistry exceeds 0.15 PPM for Cl- and/or F-,

flushing of sensitized stainless steel piping as required by 4.1.E wi 11 be performed once the RWST Water Chemistry has been brought within specification limit of less than 0.15 PPM chlorides and/or fluorides. Samples will be taken periodically until the sample indicates the Cl- and/or F- and levels are below 0.15 PPM.

Check Failures such as blown instrument fuses, defective indicators, and faulted amplifiers which result in 11 upscale 11 or 11 downscale 11 indication can be easily recognized by simple observation of the functioning of an instrument or system. Furthermore, such failures are, in many cases, revea 1ed by a1arm or annunciator action, and a periodic check supplements this type of built in surveillance.

Based on experience in operation of both convent i ona1 and nuclear unit systems, when the unit is in operation, the minimum checking frequencies set forth are deemed adequate for reactor and steam system instrumentation.

Calibration Calibration shall be performed to ensure the presentation and acquisition of accurate information.

The nuclear flux (power level) channels shall be calibrated daily against a heat ba 1ance standard to account to errors induced by changing rod patterns and core physics parameters.

e e TS 4.1-4 For the specified one month test interval, the average unprotected time is 360 hrs in case of a failure occurring between test intervals. Thus, the probability of failure of one channel between test intervals is 360 x 2.5 x 10- 6 or .9 x 10- 3 . Since two channels must fail in order to negate the safety function, the probability of simultaneous failure of two-out-of-three channels is 3(.9 x 10- 3) 2 =

2.4 x 10- 6. This represents the fraction of time in which each three-channel system would have one operable and two inoperable channels and equals 2.4 x 10- 6 x 8760 hours0.101 days <br />2.433 hours <br />0.0145 weeks <br />0.00333 months <br /> per year, or (approximately) 1 minute/year.

It must al so be noted that to thoroughly and correctly test a channel, the channel components must be made to respond in the same manner and to the same type of input as they would be expected to respond to during their normal operation. This, of necessity, requires that during the test the channel be made inoperable for a short period of time. This factor must be, and has been, taken into consideration in determining testing frequencies.

Because of their greater degree of redundancy, the 2/4 logic arrays provide an even greater measure of protection and are thereby acceptable for the same testing interval. Those items specified for monthly testing are associated with process components where other means of verification provide additional assurance that the channel is operable, thereby requiring less frequent testing.

e e TS 4.l-4a Flushing During construction of the facility, stress relieving of some 6f the cold bent stainless steel piping resulted in the piping becoming sensitized to potential stress corrosion cracking under certain conditions, e.g. low pH in conjunction with high chlorides. The subsystems containing the sensitized piping were identified in Stone

& Webster Report SW-MER-IA dated July 6, 1971 and further evaluated in Virginia Power Technical Report ME-0009, Rev. 1, dated December 9, 1987. The sensitized piping was either not wetted, reheat treated, or is justified as acceptable becau~e it is in a wetted system with adequate chemistry control i.e., chlorides and/or fluorides (Cl and/or F-) less than 0.15 ppm. These subsystems are as follows:

Subsystem Remarks

1) Recirc. spray inside containment Not Wetted

2) Recirc. spray outside containment Not Wetted

3) Containment spray inside containment Not Wetted

4) Containment spray outside containment Wetted

5) Low hd. SI pump discharge Wetted

6) Low hd. SI pump to 1st iso. valve Wetted

7) High hd. SI inside containment Wetted

8) High hd. SI pump discharge Wetted

9) RHR Wetted

10) Charging and letdown system in containment Flowing System *

11) Pressurizer relief lines Reheat Treated Prior to Operation

12) Pressurizer spray &surge lines Flowing System The sensitized piping found in a wetted system is acceptable as long as the fluid in or passing through the piping is less than 0.15 PPM Cl- and/or F-. The wetted systems are supplied from the RWST with the exception of the RHR system which communicates directly with the RCS during plant shutdowns. The RHR system does not communicate with the RWST during power operations and therefore, does not require flushing if Cl- and/or F- concentration exceeds 0.15 ppm.

The acceptance criteria for the piping are based on the RWST Water chemistry staying below 0.15 PPM chlorides and/or ffoorides. If the RWST chemistry on chlorides and/or fluorides is out of specification the sensitized piping that is normally supplied by the RWST will be flushed per tables 4.l-3A and 4.1-38 for Units 1 and 2 respectively.

Each refueling outage the wetted systems are flow tested ,or put in service which will flush the strategic portions of those systems.

TS 4.1-5 The refueling water storage tank is sampled weekly for Cl and/or F contaminations. Weekly sampling is adequate to detect any inleakage of contaminated water.

The control room ventilation system is required to establish a positive differential pressure in the control room for one hour following a design basis loss-of-coolant accident using a bottled air supply as the source of air. The ability of the system to meet this this requirement is tested by pressurizing the control room using the ventilation system fans and comparing the vo 1 ume of air required to that stored. The test is conducted each refueling interval (approximately 12 to 18 months), normally coinciding with the refueling outage of either Unit 1 or Unit 2.

TS 4.1-10 TABLE 4.1-2B MINIMUM FREQUENCIES FOR SAMPLING TESTS FSAR SECTION DESCPRIPTION TEST FREQUENCY REFERENCE

1. Reactor Coolant Liquid Radio-~hffjcal Monthly( 5)

Samples Analysis Gross Activity( 2) 5 days/week( 5) 9 .1 Tritium Activity Weekly 9.1

• Chemistry (CL, F & 0) 5 days/week 4

• Boron Concentration 2 Twice/week 9.1 E Determination Semiannuallyg~

DOSE EQUIVALENT I-131 Once/2 weeks( 6)

Radio-iodine Once/4 hours Analysis (including I- and ( 7)

• be 1ow 131, I-133 & I-135)

2. Refueling Water Storage Boron Concentration Weekly 6 Chemistry (Cl & F) Weekly

3. Boric Acid Tanks *Boron Concentration Twice/Week 9.1

4. Chemical Additive Tank NaOH Concentration Monthly 6

5. Spent Fuel Pit *Boron Concentration Monthly 9.5

6. Secondary Coolant Fifteen minute degassed Once/72 hours 10.3 band q activity DOSE EQUIVALENT I-131 Monthly( 4)

Semiannually(B)

7. Stack Gas Iodine and *I-131 and particle Weekly Particulate radioactive releases

8. Accumulator Boron Concentration Monthly 6.2

• See Specification 4.1.D (l) A radiochemical analysis will be made to evaluate the following corrosion products: Cr-51, Fe-59, Mn-54, Co-58, and Co-60.

( 2) A gross beta-gamma degassed activity analysis shall consist of the quanti-tative measurement of the total radioactivity of the primary coolant in units of µCi/cc.

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TABIE 4. l -3A UNIT 1 MINDEM ~ FOR FIIJSIDNG SENSITIZED PIPE Flush Flow Path General Description Flush [)]ration Frequency

1) Contairnnent Spray Pump Discharge Note 1 Note 2

2) IDw Hd SI Pump Discharge Note 1 Note 2

3) lJ:M Hd SI Pump up to 1st Iso. Valve Note 1 Note 2

4) High Hd SI Pump Inside Contairnnent Note 1 Note 2

5) High Hd SI Pump Discharge Note 1 Note 2 Note 1: Flush until sample is below 0.15 PFM Cl- and/or F-Note 2: When RWST Chemistry has exceeded O.15 Pm Cl- andjor F- (only after restoring the RWST Chemistry to spec for Cl- and/or F-)

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'I2IBIE 4.1-3B UNIT 2 MINIHJM. ~ FOR FIIJSHING SENSITIZED PIPE Flush Fl.OW' Path General Description (Ref. S&W Reoort sw-MER-lA} Flush Drratian Frequency

1) Containment Spray Pump Discharge Note 1 Note 2

2) I.ow Hd SI Pump Discharge Note 1 Note 2

3) I.ow Hd SI Pump up to 1st Iso. Valve Note 1 Note 2

4) High Hd SI Pump Inside Contairnnent Note 1 Note 2

5) High Hd SI Pump Discharge Note 1 Note 2 Note 1: Flush until sample is below 0.15 PIM Cl- andjor F-Note 2: When RWST Chemistry has exceeded o.15 PIM Cl- andjor F- ( only after restoring the RWST Chemistry to spec for Cl- and/or F-)

N I

e e ATTACHMENT 2 Discussion of Proposed Change

DESCRIPTION OF CHANGE Sensitized stainless steel was used in several safety-related p1p1ng systems during the construction of Surry Power Station. Due to the susceptabil ity of this material to accelerated corrosion (cracking) when halogens (Cl- & F-) are present, the sensitized stainless steel was discussed in our FSAR submittals as well as at . the ASLB hearing. Based on a review of the ASLB hearing transcript (March 1972) and the NRC Safety Evaluation Report (February 23, 1972), our commitments for sensitized stainless steel are to increase the inservice inspection frequency to l times normal and periodically flush those lines to prevent contaminant buildup.

At this time we are performing monthly flushes of those lines that are wetted with borated water but not flowing i . e. , portions of the containment spray, low head safety injection and high head safety injection systems. Based on our evaluation, we cannot postulate any mechanism that over an operating cycle could evaporate a sufficient volume of liquid contained within these systems that could cause chloride and/or fluoride con cent rat i oris to reach O.15 ppm, the level where accelerated corrosion could occur. The RWST water chemistry normal operating range is 20-25 ppb for Cl- and 1-2 ppb for F-. The RWST is normally sampled weekly for Cl- and F- concentration. A requirement to perform weekly sampling for Cl- and F- concentration is being added to Technical Specification 4.l-2B. Additionally, each refueling outage these systems are flow tested to the core or recirculated back to the RWST, using RWST water which replaces (flus hes) the stagnant water from the norma 11 y nonflowing lines. Therefore, we are prop.osing that the periodic flushing of the sensitized stainless steel lines be changed to "whenever the Cl- and/or F-concentration exc~eds 0.15 ppm in the RWST" and the flush duration be changed to "flush until sample is below 0.15 ppm Cl- and/or F-" (and approaching typical RWST chemistry results for:_ Cl- andjor F-). Additionally, a requirement to sample the RWST for Cl and/or F on a weekly basis is being included. *

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10 CFR 50.91 SIGNIFICANT HAZARDS REVIEW In accordance with the provisions of 10 CFR 50.91, we are providing an analysis for the issue of no significant hazards cons i de ration, using the standards of 10 CFR 50.92 and the guidance provided in Generic Letter 86-03.

We have cone l uded that these proposed changes do not involve a significant hazard. Specifically, operation of the facility in accordance with the proposed changes would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated. Eliminating the requirement to flush safety system piping, when the water chemistry does not exceed 0.15 ppm chlorides and/or fluorides, does not alter plant operation or plant design in any manner. The RWST will be sampled weekly to monitor Cl- and F- concentrations. As long as the Cl- and/or F-concentration remains below 0.15 ppm the potential for stress corrosion cracking of the sensitized piping is precluded.

2. Create the possibility of a new or different kind of accident from any ace i dent previously evaluated. These proposed changes do not involve any physical alterations to the plant or to procedures which introduce any new or unique operational modes or accident precursors. Additionally, the proposed changes are consistent with industry experience in that sensitized stainless steel is not susceptible to stress corrosion cracking when chlorides and/or fluorides concentrations are less than 0.15 ppm.

3. Involve a significant reduction in the margin of safety. The system operation and design are not altered by this change. Modification/

clarification of pipe flush frequencies to eliminate flushing that is not required does not reduce any margin of safety. Additionally, the current safety analysis remains bounding; therefore, no margin of safety is reduced by this change.