ML19095A746

Submit Abnormal Occurrence Report No. AO-S1-75-11 Re Developing of Pinhole Leak in Recirculation Line on Charging Pump 2-CH-P-1C, Causing Ventilation Vent Sampler to Alarm

ML19095A746
Person / Time
Site:	Surry
Issue date:	07/11/1975
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	Moseley N NRC/RGN-II
References
Serial No. 512-S LER 1975-011-00
Download: ML19095A746 (5)

Text

VIRGINIA. ELECTRIC AND POWER COMP.A.NY RICHMOND, VIRGINIA. 23261 July 11, 1975 Mr. Norman C. Moseley, Director Serial :tiro. 512-S Office of Inspection and Enforcement PO&M/JTB:clw United States Nuclear Regulatory Commission Region II - Suite.818 Docket Nos. 50-280 230 Peachtree Street, Northwest License Nos. DPR-32 Atlanta, Georgia 30303

Dear Mr. Moseley:

Pursuant to Surry Power Station Technical Specification.6.6.B.l, the Virginia Electric and Power Company hereby submits forty (40) copies of Abnormal Occurrence Report No. AO-:Sl-75:..*Jl.

The substance of this report has been reviewed by the Station Nuclear Safety and Operating Committee and will be placed on the _agenda for the next meeting of the System Nuclear Safety and Operating Committee.

Very truly yours,

~ )/21. #/dtur C. M. Stallings Vice President-Power Supply and Production Operations Enclosures 40 copies of Ao....:s1..,7S-:ll -

cc: Mr. K. R. Goller Mr. Bryce P. Schofield Director, Bureau of Industrial Hygiene

LICENSEE EVENT REPORT Supplemental Report I

~ ~ AO-Sl-75-11 I l,

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@El 7 8 9 I VI A I s I Pl sl 114I 10101-1 ol 15 010 lo 1°1-1°1 °1 1411 I 1111 oi 10111 25 26 30 31 32 .

REPORT REPORT CATEGORY TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE

@E]coN;T Ip I o I Lu L!J lol sl ol~lo j 2j 8jo I jOj4jll6j7j5j joj1j1joj1lsl 7 8 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION

~ jDuring normal operation a "pinhole" leak developed in the recirculation line on 7 8 9 80 I

~ !charging pump 2-CH-P-lC, causing the ventilation vent sampler (RMS-VG-109) to alarm.

7 8 9 80 l

@El !This resulted in an unplanned release of radioactive material from the site. The I 7 8 9 80

~ jleak was found and isolated 30 minutes after the alarm occurred. J 7 8 9 80 lfil§] AO-Sl-7 5-11 7 8 9 PRIME 80 SYSTEM CAUSE COMPONENT COMPONENT CODE CODE COMPONENT CODE SUPPLIER MANUFACTURER VIOLATION

@El IP IC I tu I Pl 1IP IE I xix] ~ I z 19 19 19 I L!:J 7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION

~ IA two inch stainless steel line (Type A312-TP304) developed a small pinhole leak at I 7 8 9 80

~ ja weld causing the leakage of radioactive liquid.

7 8 9 80 I

IT§ 7 8 9 80 FACILITY METHOD OF STATUS  % POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION 7

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9 I 1 I O I O12I 10 13 N/A 44

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45 IN/A 4~6------------------8._.JO FORM OF ACTIVITY CONTENT rn w RELEASED OF RELEASE lli.J I AMOUNT OF ACTIVITY 897.2 µCi I Auxiliary LOCATION OF RELEASE building vent to atmosphere 7 8 9 10 11 44 45 80 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION IT§ lo I 01 01 ~ I N/A 7 8 9 11 12 13 80 PERSONNEL INJURIES NUMBER DESCRIPTION

-~IO 7 8 9 I 01 0111 N/A 1';:;2---------------------------------------.J80

. OFFSITE CONSEQUENCES 7

rn 8 9 I The health or safety of the public was not affected.

80 LOSS OR DAMAGE TD FACILITY TYPE DESCRIPTION D}J 7 8 W

9 N/A 10~-----------------------------------------8_JO PUBLICITY ITlzl N/ A 7 8 9 BO ADDITIONAL FACTORS (2@ N/A 7 B 9 80 7

liliJ8 9 80 NAME: E. M. Sweeney, Jr. PHONE: (804) 357-3184 GPO 6Bl 0 667

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) e ,R\egulatory Docket J.1~

- -~ . ----'----~-~_,.s .. _-----J SUPPLEMENTARY INFORMATION ON AIRBORNE PARTICULATE ACTIVITY RELEASE ABNORMAL OCCURRENCE AO-Sl-75-11 At approximately 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on April 16, 1975, the Ventilation Vent Sample (RI-VG109) alarmed indicating a high airborne particulate activity in the auxiliary building general area exhaust. At approximately 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br /> a pinhole leak was discovered on the charging pump recirculation line for 2-CH-P-lC. The I recircul;1tion line isolation valve was immediately shut and a piece of protective -1 clothing was wrapped around the leaking pipe to stop the dispersion of reactor coolant into the air. At approximately 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> the affected charging pump (2-CH-P-lC) was isolated and drained thus completely stopping the leak. It is conservatively estimated that a maximum of 25 gallons of reactor coolant leaked from the charging system. An inspection of the Ventilation Vent Particulate radiation monitor chart (RI-VG103) shows that airborne particulate activity was released from the site for about one hour.

The identity and concentrations of the radionuclides actually present in the Ventilation Vent as a result of this leak were not determined. Therefore, it is assu~ed that all activities normally present in the charging system were present during the leak and in their normal concentrations. It is also assumed that 10 per cent of the particulate activity in the coolant actually b~came airborne. The activities present were as follows:

FROM RADIONUCLIDE CONCENTRATION {µCi} MPC {10 CFR 20} {µCi}

ml ml co58 1. 31 X 10-3 2 X 10- 9 ca60 1. 73 X 10- 3 3 X 10-l 0 Mn54 2.76 X 10- 3 1 X 10-9 Na24 4.0 X 10- 3 5 X 10-9 csl34 3.74 X 10-3 4 X 10-10 csl37 9.44 X 10-4 5 X 10-l O csl38 1.27 X 10-2 3 X 10- 8 H3 6.78 X 10- 2 2 X 10-7 The release rates in Ci/ sec for each of the above radionuc lid.es were as follows:

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RADIONUCLIDE

• RELEASE RATE {Ci/sec}

co58 3.44 X 10- 9 co60 4.54 X 10- 9 Mn54 7.24 X 10- 9 Na24 1. 05 X 10- 8 csl34 9.82 X 10- 9 csl37 2.48 X 10- 9 csl38 3.33 X 10- 8 H3 1. 78 X 10- 7 Technical Specification 3.11 requires that the controlled release rate of airborne particulate activity be governed by the following relationship:

I:Qi

~(~MP~C~)-i-..::;__ 2.0 x 10 5 m3 sec Qi is the release rate of any radionuclide i MPCi is the maximum permissible concentration of any radionuclide i from Appendix B, Table II of 10 CFR 20. MPCi must be reduced by a factor of 700 for any halogen or particulate activity with a half life of _greater than eight days. Qi for each radionuclide released was as follows: (MPC) i Qi m3 (MPC).l -sec RADIONUCLIDE co58 1.20 X 10 3 co60 1.06 X 104 Mn54 5.06 X 10 3 Na24 2.10 csl34 1. 72 X 104 csl 3 7_ 3.47 X 103 csl38 1.11 H3 .89 r

I-

.,. -r. ' '=>

EQ. = 3.75 x 10 4 l

(MPC) .

• e m 3 or 19 per cent of the limit listed in Technical sec l

Specification 3.11 averaged over the one hour period of the release.

The calculated concentrations of radionuclides within the Ventilation Vent System were as follows:

RADIONUCLIDE CONCENTRATION {µCi}

ml co58 10.4 X 10-11 co60 13.8 X 10-ll Mn54 21. 9 X 10- 11 Na24 3.2 X 10-10 csl34 29.8 X 10-11 csl37 7.5 X 10-ll csl38 10.1 X 10-10 H3 5.4 X 10-10 The limits in Technical Specification 3.11 are based on the highest annual average value of x/Q which will occur at the site boundary (5.0 x 10- 6 seconds per meter 3). Therefore, the maximum allowable discharge rate (MADR) of radio-nuclides is given by:

~R=E _ _ _~_c_i_ _ _ x ~ = ___4_._2_3_8_x_l_0_ 8_ {Ft 3 }

Concentration i x E Concentration i MIN MPCi This results in a maximum allowable. discharge rate of 2.45 X 10 8 During the release, the Ventilation System flow was 7 x 10 4 Ft 3 or

.03 per cent of the maximum allowable. MIN It can be seen from the above calculations that the health and safety of the general public was not affected.

Two small coolant leaks have previously occurred in the charging pump re-circulation lin~s at Surry. A detailed investigation into the cause of these leaks was conducted by Vepco's engineering staff and representatives of the nuclear steam supplier. At present, the cause appears to be related to hydraulic erosion and/ or cavitation in the recirculation piping. The nuclear steam supplier has committed to evaluate this problem and establish a final recommendation for implementation at Surry Unit Nos. 1 and 2. To date this information has not been provided.