ML20198G621
| ML20198G621 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 04/21/1975 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Moore V Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1060 NUDOCS 8605290703 | |
| Download: ML20198G621 (10) | |
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a APR 21 875 l
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V. A. Moore, Assistaat Director for Light Water Reactors, Group 2, EL l
WASHINGTON PUBLIC POWER SUPPLY SYSTEM - WPPSS NOS.1 & 4, REVISED SER INPUT SY THE ACCIDENT ANALYSIS BEAL;C11 I
i Plant Names WPPSS Nos. 1 & 4 Licensing Stage: CP Docket Eiseber: 50-460; 50-513 Responsible Branch: LWR 2-3; T. Cox, LPM Raquested Completion Date April 3, 1975 Review Status: AAB Eaview Complete Enclosed are revisions to the Accident Analysis Branch (AAL) SZR input for the Washington Public Power Supply System's (WPPSS) nuclear pisats, Nos. 1 and 4 (UMP-1 and WNP-4). These revisions are i
l based upon material submitted by the applicant in Amendment No. 16, j
received March 27, 1975. The information in this amendment has ad-dressed and resolved our concerns in the areas of the spray additive l.
injdetion systas, the control room dual inlet design, the need to have the ECCS equipment area served by EST filters, and a commitment on explosives shipped past the site. We have also recalculated the LOCA dose due to a reduction in the unsprayed portion of the containment. We e
still note the need for confirmation by OELD that the applicant has reasonable assurance of control over the exclusion area.
This review was coordinated by L. Soffer, Sita Analyst, of the Accident Analysis Branch.
% Signd by
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Harold R. Dentos, Assistant Director for Site Safety Division of Technical Eaview Office of Nuclear Reactor Angulation Enclosures Revised SER Input I
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1.4 CONCLUSION
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i on the basis of the 10 CFR Part 100 definitions of the population l
center distance, the exclusion area and low population zone, our analysis i
of the on-site meteorological data from which atmospheric dilution factors f
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were calculated (see Section 2.3 of this report), and the calculated potential radiological dose consequences of design basis accidents 1
(discussed in Section 15.0 of this report), we have concluded that the exclusion area radius and low population zone and p.opulation center f
distances meet the guidelines of 10 CFR Part 100 and are acceptable.
i 2.2.1 NEARBY TRANSp0RTATION ROUTES No explosives are presntly transported on the Hanford Reservation railroad system. The applicant has obtained a commitment from ERDA, I
the operators of the railroad system, that the applicant will be in-formed prior to transport of any explosives shipments of more than 1800 pounds past the WNP-1, 2, or 4 sites, or of any plans to regularly ship explosives of a lesser quantity by rail past the UNP-1, 2, or i
4 sites. We will include in the technical specifications a requirement that the appleiant will notify the NRC of any intended change in shipment of explosives past the sites and pro.id. an analysis of any such I
change in usage. We ' conclude that rail operations on the Hanford Reservation railroad system will pose no hazard to the design and operation of these facilities.
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_6.2.3 AIR CLEANUP SYSTEMS The containment spray system is used for lodine removal from the contain-ment atmosphere fo11 ewing a postulated LOCA. Sodium hydroxide is added
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1 to the containment spray solution to enhance the iodine scrubbing function f
of the system. The system is designed to raise the spray pH to 9.0 during the injection phase of operation of the spray system. Sodium I
hydroxide addition is continued during the recirculation phase uniti the pH of the solution in the containment' sump reaches 9.0.
We have evaluated this system and conclude it is effective for removal i
of elemental iodine, and iodine absorbed on airborne particulate matter.
We calculated first order removal coefficients for elemental and particu-late iodine of 10 and 0.36 (1/hr), respectively, in an estimated effective containment volume of 2.75 x 106 3
ft The elemental iodine removal effectiveness is assumed to diminish after a decontamination factor of 100 has been achieved in the containment atmosphere. The long term sump pH of 9.0 is considered adequate to maintain the decontamination factor (DF) of 100 for the elemental iodine.
8 6.4 hah 1TABILITY SYSTEMS
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The emergency protective provisions of the control room related to the accidental release of radioactivity or toxic gates are evaluated in this section.
Relevant portions of the control room ventilation system are described here but are described and evaluated more fully in Section 9.4 6.4.1 RADIATION PROIECTION PROVISIONS t
l The applicant proposes to meet General Design Criterion 19, Control Room, of Appendix A to 10 CFR Part 50, by use of concrete shielding I
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i, 3-and by installing two remote fresh air inlets to provide an assured source of clean air for pressurization.
In addition, the design incorporates a redundant 19,500 cfm charcoal filter train that processes make-up and ~ recirculated air to further ensure a habitable environment within the control room zone.
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The original design of the remote inlet system was upgtaded based on a staff position that indicated excessive operator doses after a postulated LOCA. The applicant re-evaluated the design and submitted a modified system design described in Amendment #16 of the SAR.
The system consists of a split inlet arrangement where the make-up air is taken from one of three sources, the normal inlet on the roof of the General Services Buildings or one of two remote inlets located about 1400 feet from the containment in the south and east directions.
In the event of a high radiation signal from the detector located in the normal inlet, the normal inlet is closed and one of the two remote inlets is opened. The inlet having the lowest contamination level is i
automatically selected based on the activity levels measured at the remote inlets. We have determined that the system design, location of f
the remote inleta, and method of inlet control are acceptable and will guarantee a source of uncontaminated air under all but the most extrema wind conditions.
Activation of the charcoal filter system occurs automatically upon detection,of radiation in the normal inlet. The filter processes I
10,750 cfm of make-up air from the operating remote inlet and also I
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processes 8750 cfm of recirculated control rcom air. The operation of the filter further assures a satisfactory control room environment.
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I We have calculated the Unit 1 and 4 operator doses assuming a LOCA in either of the units and have determined that the doses meet the dose guidelines of Criterion 19.
6.4.2 T0XIC GAS PROTECTION PROVISIONS Control room habitability following a p9stulated toxic gas release is required to ensure that. operators can continue to operate the plant.
' Chlorine has been identified as the only material that, if released, would pose a potential operator hazard. Provisions such as quick-acting chlorine detectors and self-contained breathing apparatus will We be provided to protect the operator against a chlorine telease.
have reviewed these provisions against the guidelines of Regulatory Guide 1.95 and have found them to be adequate. We conclude that the
~t plant's toxic gas protection is acceptable.
15.1 LOSS-OF-COOLANT ACCIDENT The containment model used to describe the dose mitigating effects of the engineered safety features proposed for the W;tP-1 and WNP-4 plants includes a single containment structure surrounding the reactor and a sodium hydroxide additive injection system operating in conjunction with the c6ntainment spray system. The purpose of n
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t i the sedium hydroxide additive injection system is to increase the iodine removal capability of the spray following the hypothetical LOCA (see Section 6.2.3).
The assumptions we used in evaluating the consequences of this accident are given in Table 15-2.
The results of the calculation indicate that the potential radiological consequences are within the guideline values of 10 CFR Part 100 and Regulatory guide 1.4 and are, therefore,.
acceptable.
As part of the loss-of-coolant accident (LOCA), we and the applicant have also evaluated the consequences of leakage of containment sump water containing radioactive fission products which is circulated by the ECCS outside the containment after a posutlated LOCA. We and the applicant assumed the sump water to contain a ' mixture of iodine fission ptoducts in agreement with Regulatory Guide 1.7.
If a source of leakage should develop, such as from an RHR pump seal, a portion of the iodine would become gaseous and would exit to the outside atmosphere. The offsite doses resulting from such a sequence of events depends upon the temperature and magnitude of the assumed leakage. If the leakage occurred when the water temperature was below 2120F, a leak rate of about 20 gpm over a period of one-half hour would result in doses (without filters) which could exceed the guide-line values of Regulatory Guide 1.4 from this source alone.
If the leakage occurred when the fluid is near its peak temperature of 270 F, then part of the leaking water would flash to steam, leading to f
additional fodine release.
In this case, about 3 gpm leakage for t
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30 minutes would result in doses (without filters) which could exceed i
the Regulatory Guide 1.4 values.
Since the area where the ECCS.! equipment is located is served by filters which conform to the requirements of engineered safety features and are effective in removing iodine, the off-site doses from possible pump leakage in this area will be a small contributor to the LOCA dose, I
t even for substantial amount of leakage.
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TABLE 15.1 sg s
Potential Offsite Doses Due to Design Basis Accidents Bio-Four Course of Accidi Exli:usion Boundary Low Population :
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(1950 meters)
(6440 neters)
Thyroid Whole Body Thyroid Whole Es i Accident
(rem)
(rem)
Loss-of-Coolant 127f 7
45 2
Post-LOCA Hydrogen Purge Dose 82 9.2 Fuel Handling 5
2
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<1 1
l Rod Ejection
- Case I 100
<1 54
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Case II 120 3
h Gas Decay Tank Rupture Negligible 20 Negligible 2 See Section 15.4 of this report for the different assumptions used for Cases I and II.
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