ML20205J468

Ack Receipt of Draft Guidelines for Permanent BWR Hydrogen Water Chemistry Installations. Formal Review of Guide Will Not Be Conducted.Comments Re Potential plant-specific Hydrogen Chemistry Mods Submitted

ML20205J468
Person / Time
Issue date:	02/07/1986
From:	Bernero R Office of Nuclear Reactor Regulation
To:	Neils G BWR OWNERS GROUP
References
NUDOCS 8602260017
Download: ML20205J468 (2)

Text

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e %D '%,,,,,/ FEB 0 71986 Mr. G. H. Neils Chairman, Regulatory Advisory Committee BWR Owner's Group 11 for Intergranular Stress Corrosion Cracking Research 414 Nicollet Mall Minneapolis, Minnesota 55401

Dear Mr. Neils:

We have received the draf t of " Guidelines for Permanent BWR Hydrogen Water Chemistry Installations", you sent to Mr. Harold Denton on October 12, 1985 for staff review. The staff has supplied informal comments on this Draft which were given to the Owner's Group on October 9, 1985. On February 5, 1985, we received the Final Guide and intend to provide comments on its I content. However, the staff will not conouct a formal review of the Guide since its intended applicaticns are to support plant specific modifications to be performed assuming there are no unreviewed safety questions under the i provisions of 10 CFR 50.59. Any specific modifications performed at a facility under the provisions of 10 CFR 50.59, including Hydrogen Water j Chemistry modifications would be subject to the regular inspection process I and 10 CFR 50.59 review. The following comments are relevant to potential plant specific Hydrogen Chemistry Modifications. Many aspects of potential Hydrogen Water Chemistry j Modifications appear to be of the type of modifications that will be able to be carried out without license amendment under the criteria of 10 CFR 50.59. Suitable comprehensive evaluation of whether or not the modifications constitutes an unreviewed safety question for the specific facility should be included as a part of the Safety Evaluation supporting the modification. Some aspects of potential hydrogen water chemistry modifications, in particular the permanent installation storage and use of relatively large quantities of liquid hydrogen on site at a specific facility, appear to { raise the concern of potentially new and different accidents from those l previously considered and evaluated as a part of the facility licensing The determination of whether or not the hazards associated with process. the potential explosion and fire hazards from the storage and use of relatively -large quantities of liquid hydrogen and/or oxygen at a specific facility require careful consideration by a licensee when reaching a determination as to whether a proposed modification involves any of the three criteria for "anunreviewedsafetyquestion"definedin10CFR50.59(a)(2). I

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I d FEB 0 71TS Mr. G. H. Neils -2 Mr. Robert A. Hermann of my staff will remain as the staff contact for this work and will be available to work with the Owner's Group on this subject. Nietmu % Robert 5.* W Nche M (g - 4ctor Division of BWR Licensing DISTRIBUTION Central File RBernero JZwolinski RHermann w/cy of incoming CJamerson PPAS NRC POR (w/ incoming) HDenton DEisenhut HThompson FMiraglia TSpeis WRussell DMuller EAdensam WButler BDalrymple FWitt BDLiaw WHodges DVassallo MSrinivasan Glainas ~, - -' ~~ .t e ) \\) I' i \\ \\ \\ i / DBL:PD#1 DBL:PD#1 OELD BW AD UBUg DBL:DIR RHermann:jg JZwolinski JScinto G firas Rf6uston RBernero .'/////86 i /i /86 / /86 \\V/pV/86 j/p/86 2 / 7/86 6

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Northern States Power Company l y; en die Nicollet MJW RAinneapons. Minnesota 5540 Tewohone (6t21330 5500 January 27, 1986 Mr. Harold Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Guidelines for Permanent BWR Hydrogen / Water

Subject:

Chemistry Installations Enclosed are three copies of the report entitled " Guidelines for Permane This. report was prepared by BWR Hydrogen Water Chemistry Installations".the BWR Own l received from ACRS and NRC Staff related to a previous draft. i The BWROG requests NRC concurrence that implementation of permane hydrogen water chemistry installations, performe 50.59. This document was prepared and is provided on behalf of the BWROG w objective of reducing the licensing burden for both BWR licensees and NRC Staff for the implementation of permanent hydrogen water chemistry Although the BWP0G has approved the guideline report as such this does not necessarily represent a commitment of any specific installations. licensee to utilize this particular mitigation method in their overall plans. The BWROG anticipates that, upon NRC Staff con addressed piping replacement under 10CFR 50.59. Please call me if you have any questions on this information. Sincerely, </#f/D G. H. Neils. Chairman Regulatory Advisory Comittee BWR %ners Group II fnr IGSCC Research R. hones /EPRI cc: /N 0 W 'q.

UNITED STATES NUCLEAR REGULATORY COMMISSION [ g wasmmatow.o.c.aones t; p December 11, 1985 9 NOTE T0: R. Wayne Houston, Deputy Director Division of BWR Licensing I FROM: John A. Zwolinski, Director BWR Project Directorate il Division of BWR Licensing i RESPONSE TO BWROG REQUEST ON HYDROGEN WATER CHEMI

SUBJECT:

OCTOBER 21, 1985 g. Per our telecon we are infoming you that some issues require resolution t They are: prior to issuing the attached letter to the Owner's Group. This item is a policy issue, and, as such should be reviewed by 7* We understand that the unreviewed safety question aspect l 1. OELD. We believe that the noticing of has been discussed with OELD. potential amendments, considering the fact that the guidelines t would tentatively be an approved topical report, as a significant hazard or no significant hazard needs discussion with OELD prior to issuance of this letter. Our perception that the staff needs to provide a position regarding whether or not this item is an unreviewed safety question prior to 2. completing the subject review. The need to provide our position to the BWROG regarding our detemination on 10 CFR 50.59 prior to completion of our review. 3. The impact of our determination on current plant - specific activities being discussed with the NRC, re. those at Dresden 4. and Pilgrim Stations. ? t d 1//' N

f i . December 11, 1985 i R. Wayne Houston We are proposing to meet within G. Lainas and J. Hulman on these issues We feel a meeting with OELD (Scinto) is necessary. on December 12, 1985. 17, 1985. The yellow ticket Mr. Scinto returns from leave on December We believe it is prudent to response date for the item is mid-March. resolve these questions pri i i t John A. Zwolinski, Director BWR Project Directorate il ) Division of BWR Licensing i L

Attachment:

As stated cc: G. Lainas J. Hulman R. Bernero CONTACT: R. Hermann, BWR PD #1 x27385 I V h, 9 8 O e

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l c Mr. G. H. Neils Chairman, Regulatory Advisory Committee BWR Owner's Group 11 for Intergrandular Strpss Corosion Cracking Research i-414 Nicollet Mall Minneapolis, Minn. 55401 e

Dear Sir:

o We have received the draft of " Guidelines for Pennanent BWR Hydrogen Water i Chemistry Installations", you sent to Mr. Harold Denton on October 21, 1985 [ for staff review. f The staff has supplied informal comments on this Draft which were given to the Owner's Group on October 9, 1985. We will make no further coninents on n the Draft, but will conduct a formal review of the Final Guide when received. i Haterial studies have been conducted in a hydrogen water chemistry environment ~ at Dresden 2, in Swedish BWR's and in extensive laboratory testing. On the basis of this infonnation it appears that hydrogen vater chemistry of I the type your group proposed can be an effective interpranular stress ) corrosion cracking countermeasure. In our judgment the permanent installation of the hyt'.rogen water chemistry system does not meet the criteria for implementation under 10 CFR 50.59. Specifically, the additional bazards associated with personnel exposures to Nitrogen 16 radiation, and the potential explosion and fire hazards from the storage and use of hydrogen and oxygen, are unreviewed safety questions. In Therefore, a license amendment for each installation appears warranted. l order to facilitate the review of licensee amendments, the staff intends to process the proposed guidelines as a topical report, and allow individual licensees the opportunity to reference the topical report. i We believe that the processing of a plant specific license ar.iendment would be expedited when an application references the approved topit,a1 report, and when the actions proposed by a specific licensee are within the envelope of criteria that were covered in the approved topical report. Ke intend to issue guidance with regard to use of the topical report in ifcensing as part of the review process n for the document. + 1

i-2- Mr. G. H. Neils l t t I' I have asked Jerry Hulman, the Chief of Plant Systems Branch in our new organization, to take the technical lead on this subject. Bob Hermann I. will remain as the lead PM and will work with the Owner's Group regarding licensing issues. i Robert M. Bernero, Director g Division of BWR Licensing cc: H. Denton i D. Eisenhut H. Thompson F. Miraglia T. Speis I W. Russell J. Zwolinski e D. Muller E. Adensam W. Butler i l I a i P e O e 4 e

~ Northem States Power Company 414 Nicollet Mat Minneapons.Minnescta 55401 Towphone (612) 330 5500 October 21, 1985 Dr. Harold Denten Director Nuclear Reactor Regulation LS Nuclear Regulatory Camission Washington, DC

Dear Mr. Denten:

Attached is a current draf t of " Guidelines for Pemunent BWR Hydrog Chanistry Installations", pre' pared by the BWR Ovners Research. steps to facilitate Staff review of this docunent. 11, 1985, the objective of this As I infomed ycd in my letter of June to proceed with pennanent docunent is to provide a basis for licensees installations for BE hydrogen addition systans in an envircrrnent that ~ might result in minimizing the resource burden on both licensees and J NC Staf f. 'Ihe final edition of this generic guideline should be available in the next f your several weeks; however, we believe it should be nutually beneficial, i staff review could be initiated on the draft attached. l' We suggest that after NC Staff review of this gen l to the guidance letter issued on the subject of DhR piping replacanent. ,,l ! li l ! M G. H. Neils Otainnan, Regulatory Advisory Cmmittee BG Chner's Group 11 for 1GSCC Research i 4 Gis Lainas cc: e l 1 l i plpo6Qpf-Y \\ l~ 5 'N ON102185J03

G / s REVISION C DRAFT GUIDELINES FOR PERMANENT BWR HYDROGEN WATER CHEMISTRY INSTALLATIONS Prepared by BWR Owners Group for IGSCC Research Hydrogen Installation Subcommittee U i Prepared for BWR Owners Croup for IGSCC Research and Electric Power Research Institute i e e h

ABSTRACT Intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel pip-One method shown effective in ing in BWRs has resulted in costly plant outages. arresting pipe cracking and pipe crack growth is a process known as Hydrogen Water ll HWC consists of maintaining good water chemistry and adding i! Chemistry (HWC). Addition of hydrogen decreases the oxidizing power of hydrogen to the feedwater. the reactor water and reduces its aggressiveness toward plant structural I This doctrient provides guidelines for design, construction, and oper. materials. ation of permanent hydrogen injection systems at BWRs to allow implementation The scope of this document includes the currently available under 10 CFR 50.59. on-site hydrogen and oxygen supply options (i.e., compressed gas, cryogenic liquid, and electrolytic generation) and the delivery system design and controls. Included are guidelines for design, operation, maintenance, surveillance, and testing to provide for safe system and plant operation. Compliance with these guidelines will ensure that this system installation and operation will not l produce a safety concern. \\ pf( p@< ~ 1 V e e 111 s

d J ACKNOWLEDGMENTS This document was prepared by the following experienced industry personnel an effort sponsored by the BWR Owners Group for IGSCC Research and EPRI. W. Bilanin, EPRI o L. Brehm, Northern States Power Company o L. Camilli, Air Products and Chemicals, Inc. o J. Goldstein, New York Power Authority o D. Helwig, Philadelphia Electric Company o M. Ira, Tennessee Valley Authority o E. Kearney, Boston Edison Company o J. Klapproth, General Electric Company o E. Rowley, Commonwealth Edison Company o R. Scholz, Philadelphia Electric Company o T. Seeley, Stearns Catalytic Corporation o 1 4 I O l V

4 ! -* i a e 1 ) 4 i a i 1 ,i CONTENTS i 1 i .P_tSt [ ) f, Section INTR 000CT10N....................................................... 1-1 i ) 1 l Scope......................................................... 1-1 l 1.1 B ack gr ound.................................................... 1 - 2 1 i 1.2 l GENER AL SYSTEM DESCRI PTION....................................... 2-1 2 j Ge ne ral Des i gn C ri t eri a....................................... 2-1 I 2.1 Hydrogen Supply 0ptions....................................... 2-1 { 2.2 j Comme rci al Suppl i e rs.................................,.. 2-2 2.2.1 l l On-5i t e Producti on..................................... 2-2 2.2.2 l Re c ov e ry............................................... 2-2 2.2.3 Ga s I njectio n 5yst ems......................................... 2-3 t 2.3 Hydrogen Inject ion 5ystem.............................. 2-3 l 2.3.1 l 0xyge n I njecti on 5yst em................................ 2-6 1 4 2.3.2 i Instrume ntation a nd Cont ro1................................... 2-7 i l 2.4 Hydrogen Injection F l ow Contro1........................ 2-7 t 2.4.1 i 0xygen I nj e cti on F l ow Contro1.......................... 2-8 2.4.2 Monitoring.................................'............ 2-8 1 2.4.3 SU P PLY F ACI L IT I E S.................................................. 3-1 3 l Ga se ou s Hydro ge n.............................................. 3-1 l l 3.1 System 0ve rv i ew........................................ 3-1 3.1.1 l Specifi c Equi pment Description......................... 3-1 3.1.2 Li. qui d Hydr oge n............................................... 3-4 l 3.2 l Syst em 0ver vi ew........................................ 3-4 } 3.2.1 Speci f ic Equi pme nt Desc ri pt ion......................... 3-5 l 3.2.2 Site Characteristics of Geseous and Liquid Hydrogen.... 3-8 3.2;3 i El ect rol yt i c.................................................. 3-9 3.3 System 0vervi ew........................................ l 3.3.1 j Speci f ic E qui pment Description......................... l 3.3.2 i l l i 4 ' ' ' ' - - ^ -

o. ,P.3g Section 3.4 L i q u i d 0 xy ge n................................................. 3 - 14 3.4.1 Sy s t em 0ve rv i ew........................................ 3-14 3.4.2 Speci fi c Equi pment De scri ption......................... 3-14 j 3.4.3 Materials of Construction for Oxygen Piping and Va1ves............................................ 3-16 3.4.4 0xyge n C l e a ni ng................... ;.................... 3-18 3 l 3.4.5 Site Characteristics of Liquid 0xygen.................. 3-18 l 3.4.6 Properti es of Liquid 0xyge n............................ 3-19 4 S AF ETY CONSI DER AT I ON S.............................................. 4-1 q 4.1 G a s e ou s Hyd r oge n.............................................. 4 - 1 4.2 Liquid Hydrogen............................................... 4-1 4.2.1 Prope rties of Liquid Hydrogen.......................... 4-1 4.2.2 Storage Ves sel F ail ure................................. 4-2 4.2.3 P i pe 8 r e ak s............................................ 4 - 5 4.3 Electrolytic.................................................. 4-6 i; 4.3.1 Ge ne ra 1................................................ 4 - 4.3.2 P u r i ty o f Ga s e s........................................ 4 - i 4.3.3 A i r I n1 e ak a ge.......................................... 4-ll 4.3.4 Ou t Le a k a g e............................................ 4 - l; 4.3.5 Ex t e rn al E v e nt s........................................ 4 - j 4.4 L i q u i d 0 xy ge n................................................. 4-6 i 4.4.1 Liquid Oxygen Storage Vessel F a11ure................... 4-6 i; 4.4.2 Liquid Oxygen Vapor Cloud Dispersion................... 4-6 ,l 4.5 R e f e re n c e s.................................................... 4 - 7 U 9 !i 5 V E R I F I C AT I O N....................................................... 5 - 1 't 6 OPERATION, P%I NTENANCE AND TRAI NI NG............................... 6-1 6.1 Operating Procedures.......................................... 6-1 'l 6.1.1 Integration into Existing Plant Operation Procedures... 6-2 I 6.1.2 Plant Specific Procedures.............................. 6-2 .j 6.1.3 Radi ation Prot ecti on Program........................... 6-2 6.1.4 Wat e r Chemi st ry Cont ro1................................ 6-4 j 6.1.5 F uel Surve il la nce P rog ram.............................. 6-5 6.2 Maintenance................................................... 6-5 6.3 Training...................................................... 6-6 i 6.4 Identification................................................ 6-6 6.5 R e f e re n c e s.................................................... 6 - 7 vifi

133, 1

Section i 7 $U RVE I L L ANC E AND TE ST I NG........................................... 7-1 7.1 Sys tem I nt egr i ty Tes t i ng...................................... 7-1 Preoperational and Periodi c Testi ng................'........... 7-1 7.2 8 R AD I AT I ON PO N I T0R I NG............................................... 8-1 8.1 Introduction..............................'.................... 8-1 8.2 Mai n Steam Li ne R adi ation Moni tori ng.......................... 8-1 i 8.2.1 Dual MSLRM Set Poi nt Recommendat i on.................... 8-2 8.2.2 MSLRM Safety Design B asis.............................. 8-2 i 8.2.3 MSLRM Sens i ti vi ty...................................... 8-3 8.2.4 C o n cl u s i on s............................................ 8-3 Equi pme nt Qual i f i cat i o n....................................... 8-3 8.3 8.4 References.................................................... 8-4 QU AL I TY AS SUR ANC E.................................................. 9-1 i j 9 l 9.1 Syst em Designer and Procurer.................................. 9-1 Control of Hydrogen Storage and/or Generation 9.2 Eq ui pme nt S u p pl i e rs........................................... 9-1 i L 9.3 System Constructor............................................ 9-2 l APPENDIX A CODES, STANDARDS, AND REGULATIONS APPLICABLE TO HYDROGEN WATER CHEMISTRY INSTALLATIONS.................. A-1 I! .I a 6 i 4 1 1 ! a e 1 e i \\ I o t

I i

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s j.. Section 1 i INTRODUCTION ) 1.1 SCOPE This document sets forth design, construction, and operational guidelines for permanent hydrogen injection systems at boiling water reactors (BWRs) to allo l implementation under 10 CFR 50.59. As such, its purpose is to provide a reference j l NRC staff acceptance of these guidelines should mini-d document for utility use. mize the amount of plant specific evaluations required. The purpose of the hydrogen injection system is to inject hydrogen into the reac-l tor coolant, presently via the feedwater system, to reduce the dissolved oxygen l j Reducing the dissolved oxygen concentration and maintaining high l concentration. ] purity in the reactor coolant will reduce the susceptibility of reactor piping and materials to intergranular stress corrosion cracking (IGSCC). This process is l i referred to as hydrogen water chemistry (HWC). I The scope of this document includes the currently available on-site hydrogen and i oxygen gas supply options (i.e., compressed gas, cryogenic liquid, and electro-Included in l Iytic generation) and the gas delivery system design and controls. l this scope are the hydrogen injection system requirements for operation, mainte-l l nance, surveillance, and testing to provide for safe system and plant operation. l Compliance with these requirements will ensure that no significant safety concerns l exist with system installation and operation. i Requirements for short-term HWC preimplementation tests to detemine the hydroge i l flow sheet and radiological impact on a plant site are not in the scope of this l Also, system availability and other issues that are required to obtain l document. licensing cred,it for HWC (e.g., reduced in-service inspection) are not address j l There are two primary regulatory concerns related to the permanent implementation i the potential ippact of failures in the oxygen and hydrogen storage / of HWC: handling systems on the plant safety systems and increased dose rates due to l increased N-16 carry-over in the steam. For the oxygen and hydrogen storage / 1-1

-a s a ~n+, -a-g -6 m. ..s -.E' o 4 handling issue, this c.ocument addresses external events such as seismic, tornados, fire, vehicle hazards, etc. In addition, system internal events such as over-j pressurization and relief valve failures and the potential impact on plant struc-tures and control room habitability are addressed. For these events, a mech-anistic approach, as opposed to a probabilistic approach, is used as the basis for siting hydrogen and oxygen gas storage facilities. Using sufficiently conserva-j tive assumptions, the minimum distance between the hydrogen supply / generation facility and safety-related structures is prescribed. i, j Injection of hydrogen into the feedwater system of a BWR results in an approximate 3 to 5 fold increase in the activity in the steam. Consequently, HWC will result in a minor increase in the site personnel exposure. However, over the life of the plant, HWC offers the potential for significantly reduced exposures because of the l avoidance of recirculation pipe replacement and reduced pipe crack repair and i inspection. This document provides recomendations to minimize the radiological l impact of permanent HWC installations and to maintain exposures as-low-as-reasonably-achievable (ALARA). In addition, the justification for increasing the main stean if ne radiation monitor setpoint to accomodate HWC is provided. J Other issues associated with permanent HWC programs are: 4 1. Materials impact j 2. Fuel impact 3. Reactor physics impact f j 4. Equipment qualification i None of these issues will impact continued safe plant operation. Hydrogen water chemistry in combination with appropriate coolant conductivity control will sup-Press IGSCC of susceptible reactor materials, and laboratory tests have shown no j substantial concerns with hydrogen embrittlement. No significant impact on fuel performance.1s expected. Although the dissolved hydrogen concentration in the core inlet water increases slightly, the impact on core reactivity is insignifi-cant, and reactor physics will not be affected. With regards to equipment qual-i ification, dos rates inside the drywe11'close to the recirculation piping will I decrease due to the increased carry-over of N-16 in the steam. Outside the dry-l well, the increase in the dose rates is relatively small relative to the inte-grated dose assumed for qualification tests. 1 l 1-2

1 i i l d 1.2 ' BACKGROUND The recirculating coolant in Bnfts is high-purity (no additive) neutral pH water containing radiolytically produced dissolved oxygen (100-300 ppb). This level of l dissolved oxygen is sufficient to provide the electrochemical driving force needed j l to promote IGSCC of sensitized austenitic stainless steel piping and similar structural components if the other two prerequisites for IGSCC [a sensitized i microstructure (chromium depletion at the grain boundaries) and a tensile stress f above the yield stress] are also present. A variety of IGSCC remedies have been developed and qualified which address the } Another j sensitization and tensile stress aspects of stress corrosion cracking. approach for suppressing IGSCC involves modifying the BWR coolant environment to y reduce the electrochemical driv'ing force for IGSCC. The NWC technique consists of reducing the coolant oxygen level from the present f7 f200 ppb to that which, in combination with water quality, has been shown to l result in IGSCC immunity. The reduction in coolant oxygen is accomplished by the l addition of hydrogen to the feedwater and the conductivity of the coolant is reduced (if needed) by improved water quality operational practices. The presence f of hydrogen suppresses radio-.ic oxygen fomation. The feasibility of suppres-j sing oxygen by this approach has been demonstrated in short-term demonstrations in j-eight BWRs. A long-term verification test which will extend over two or three 18-month fuel cycles was initiated at Dresden-2 in April 1983. An extensive laboratory investigation of the material perfopance consequences of t l combining oxygen suppression with conductivity control has demonstrated that sub-l stantial mitigation and possibly complete suppression of IGSCC could be achieved ] 9 gf280*C water with less than 20 ppb dissolved oxygen content if the conductivit l was maintained below about 0.3 )s/cm. Results of slow strain rate tests at Dresden-2 confirmed the anticipated improvement in the IGSCC resistance of sen-l l!' sitized austenitic stainless steel under HWC conditions and also supported other j laboratory data indicating that HWC is a more innocuous service environment for' most BWR plant structural materials than the non-HWC environment. s I } l 3 1-3

4 Section 2 GENERAL SYSTEM DESCRIPTION For this Figure 2-1 shows the hydrogen addition system in simplified fom. report, the system is divided into hydrogen supply, oxygen supply, hydrogen infec-tion, and oxygen injection systems. Options for hydrogen supply are discussed briefly below, and the main options are described in detail in Section 3. Oxygen supply is also described in Section 3. Also described in this The gas injection systems are described in this chapter. chapter are instruments and controls applicable to the entire system. 2.1 GENERAL DESIGN CRITERIA The hydrogen water chemistry system is not safety-related. Equipment and compo-nents need not be redundant (except where required to meet good engineering prac-tice), seismic category I, electrical class IE, or environmentally qualified. 4 l Nevertheless, considerations of such things as proximity of system components to other plant systems or components that are safety-related require special consid-eration in the design, fabrication, installation, operation and maintenance, etc., of certain components of the HWC system. I Dissolved oxygen concentrations in the recirculation water should be low enough to f suppress IGSCC at all reactor power levels at which the hydrogen addition system ) is operating. This is expected to be less than 20 ppb. 2.2 HYDROG5N SUPPLY OPTIONS Hydrogen can be supplied from three soJrces: (1) a commercial hydrogen supplier; (2) onsite pr5 duction from raw materials; or (3) recovery and recycle of hydrogen, from the off-gas system. Any combination of these three methods may, in princi-ple, be appropriate at a given facility. 2-1

Feedwater or condensate booster l pump COND./ R.P.V. OXYGEN = r =- P.YORCGEN. ; SUPPLY SUPPLY TEM HYDROGEN OXYGEN INJECTION IN JECTION-SUBSYSTEM SUBSYSTEM I t 1 FIGURE 2-1 HYDROGEN ADDITION SYSTEM. l

2.2.1 Commercial Suppliers Hydrogen can be obtained commercially from two types of sources: (1) merchant producers (i.e., companies that make hydrogen for the purpose of selling it to others) and (2) by-product producers (i.e., companies that produce hydrogen only as a by-product of their main business). Detailed considerations for a hydrogen supply facility acquired by a utility in this way, whether the hydrogen be supplied as a high pressure gas or as a cryo-genic liquid, are described in Sections 3.1 and 3.2 of this report, respectively. 2.2.2 On-Site Production Industrial processes for hydrogen production can be divided into two groups: electrolysis of water and thermochemical decomposition of a feedstock that con-tains hydrogen. Detailed considerations for onsite production of hydrogen by electrolysis are described in Section 3.3 of this report. All other processes for producing high purity hydrogen involve thermochemical decomposition of hydrogen-containing feedstocks followed by a series of chemical and/or physical operations that concentrate and purify the hydrogen. While these processes are feasible, in principle, they are not currently envi-sioned for implementation. Therefore, these processes are not addressed in this report. 2.2.3 Recovery Many processes are commercially available for separating, concentrating, and pur-ifying hydrogen from refinery or by-product streams or for upgrading the purity of manufactured, hydrogen. Processes are also being developed for the recovery and storage of hydrogen by the formation of rechargeable metal hydrides. f Although recovery of hydrogen is a viable option, near-term implementation of this, option is not envisioned. Therefore, this option is not addressed in this report. O f 2-2

=. ~. 4 s 2.3 GAS If0ECTION SYSTEMS Hydrogen Injection System 2.3.1 _ The hydrogen f rdection system injects hydrogen into the condensate /feedwater It includes all flow control and flow measuring equipment and all neces-system. sary instrumentation and controls to ensure safe, reliable operation. 2.3.1.1 Infection Point Considerations. Hydrogen shall be injected into the condensate /feedwater system at a location that provides adequate dissolving and mixing and avoids gas pockets at high points in the feedwater piping. Experience has shown that injection into the suction of feedwater or condensate booster pumps is feasible. Injection into feedwater pumps will require hydrogen at high pressures (e.g., 150-600psig). This may require either a cryogenic hydrogen pump or a compressor, depending on the supply option chosen. In the case of a liquid hydrogen storage system, this can also affect the sizing of the liquid hydrogen tank. There may be pressure fluctuations in feedwater systems, depending on reactor-power level and pump performance. The hydrogen addition system shall be designed to accommodate the full range of such fluctuations. 2.3.1.2 Codes and Standards. This system shall be designed and installed in accordance with OSHA standards in 29 CFR 1910.103. Equipment and piping shall be designed and f abricated to the appropriate edition of ANSI B31.1 or B31.3 for pressure-retaining components. Such components shall meet all the mandatory requirements and material specifications with regard to manufacture, examination, repair, testing, identification and certification. 1 Storage containers, if used, shall be designed, constructed, and tested in accor-dance with appropriate requirements of ASME B&PV Section VIII or API Standard 620. All welding skall be performed using procedures meeting requirements in AWS D1.1, - ANSI B31.1 or B31.3, or ASME B8PV, Section IX, as appropriate. Inspection and testing shall be in accordance with requirements in ANSI B31.1, ANSI B31.3, or API 620, as appropriate. 2-3

t System design shall also conform with NUREG-0800,10CFR50 Appendix R and appro-Each utility is priate standards and regulations referenced in this document. responsible for identifying additional plant-specific codes and standanfs that may be apply, such as State-imposed requirements, Uniform Building Code, ACI or AISC f standards. Piping shall be marked or identified in accordance with ANSI 235.1. 2.3.1.3 System Design Considerations. Hydrogen piping from the supply system to the plant may be above or below ground. Piping below ground shall be designed for the appropriate soil conditions, such as frost depth or liquefaction. ~ Piping below ground shall be designed for expected vehicle loads. Guard piping around hydrogen lines is not required, but each utility should consider providing it for such purposes as heavy traffic loads, monitoring, or isolation from nearby equipment, etc. Excess flow valves should be installed in the hydrogen line at appropriate loca-tions, to restrict flow out of a broken line so that in case of a line break flammable concentra1. ions cannot be reached so as to not affect the plant safe shutdown analysis per 10CFR50, Appendix R. l Individual pump injection lines shall contain a check valve to prevent feedwater f' from entering the hydrogen line and protect upstream hydrogen gas components. Automatic isolation valves should be provided in each injection line, to prevent l hydrogen injection into an inactive pump. Purge connections shall be provided to allow the hydrogen piping to be completely I purged of air before hydrogen is introduced into the line. Nitrogen or another inert gas shall be used as the purge gas. Geses shall be purged to safe loca-tions, either directly or through intervening flow paths, such that personnel or explosive h'azards are not encountered and undesirable quantities of gas are not infected into the reactor. ,i Area hydroged concentration monitors are an acceptable way to ensure that hydrogen-I: concer.tration is maintained below the flammable limit. If used, such monitors should be located at high points where hydrogen might collect and/or above use points that constitute potential leaks. 2-4

Sleeves or guard pipes can be used as an alternative method to mitigate the conse-quences of a line break. A hydrogen addition system will increase the hydrogen concentration in the feedwater, reactor, steam lines and main condenser. Each of these systems shall be reviewed for possible detrimental effects. A discussion of possible concerns is presented below. 1. Main Condenser The main condenser presently handles combustible gases. The hydrogen addition system does not significantly change the concentration of non-condensables. 2. Off-Gas System Oxygen shall be added to recombine with the increased hydrogen flow into the off-gas system. The net effect will be an increased heat input into the recombined off-gas. The utility should review the off-gas system to ensure that it remains conservatively designed. 3. Steam Piping and Torus Hydrogen water chemistry may slightly increase the hydrogen additun rate to the torus via the safety relief valves. i However, oxygen blowdown is decreased. Thus, the possibility 4 of forming a combustible mixture is not significantly increased i when compared to non-HWC operation. t j 4. Sumps j There are three sources of sump water that may be affected by HWC: main condenser condensate, feedwater and reactor water. For sumps which receive water from any of these three sources, j the average hydrogen concentration in the water may increase slightly. The maximum expected hydrogen in the sump atmosphere should be determined to ensure that the hydrogen concentration remains below the lower combustible limit of hydrogen in air. I 2.3.2 Oxygen Injection System i The oxygen injection system injects oxygen into the off-gas system to ensure that all entrained hydrogen safely recombines. It includes all necessary flow control and flow measurement equipment. 2.3.2.1 Injection Point Consideration. Oxygen should be injected into a portion of the off-gas system that is already diluted and has no portion of the system that could become undiluted. If this is not possible, other system design 2-5

considerations shall be provided in plant-specific cases to reduce the chances for off-gas fires. f 2.3.2.2 Codes and Standards. The systen shall be designed and installed in accordance with OSHA standards in 29 CFR 1910.104, and CGA G4.4, Industrial Practices for Gaseous Oxygen Transmission and Distribution Piping Systens. Equipment and piping shall be designed and fabricated in accordance with the appropriate edition of ANSI B31.1 or ANSI B31.3. Additional guidance on materials of construction for oxygen piping and valves is given in Section 3.4 of this report, and in ANSI / ASTM G63, Evaluating Nonmetallic Materials for Oxygen Service. Welding shall be performed using procedures meeting requirements of AWS D1.1 or ASME B&PV, Section IX, as appropriate. Piping shall be marked or identdied in compliance with ANSI 235.1. Inspection and testing shall be in accordance with requirements in ANSI B31.1 or ANSI B31.3, as appropriate. System design shall also confonn with appropriate PFPA, CGA, and other standards and regulations referenced elsewhere in this document. Each utility is respon-sible for identifying additional plant-specific codes and standards that may apply, such as State-imposed requirements, Uniform Building Code, ACI or AISC standards. 1 2.3.2.3 Cleaning. All portions of the system that may contact oxygen shall be cleaned as described in Section 3.4 of this report, and in accordance with CGA l G-4.1, Cleaning Equipment for Oxygen Service. 2.4 INSTRUMENTATION AND CONTROL This subsection discusses the instrumentation, controls, and monitoring associated j, with the hydrogen addition system. s The instrumentation and controls include all sensing elements, equipment and valve operating hand switches, equipment and valve status lights, process information instruments, and all automatic control equipment necessary to ensure safe and reliable operation. Table 2-1 lists the recommended system trips. ) l 2-6

The instrumentation shall provide indication and/or recording of parameters neces-sary to monitor and control the system and its equipment. The instrumentation shall also indicate and/or alarm abnormal or undesirable conditions. Table 2-2 lists the recommended instrumentation and functions. This table also includes instrumentation for hydrogen and oxygen supply options. System instramentation and controls shall be centraitzed where feasible to facili-tate ease of control and observation of the system. As a minimum, there shall be a systen trouble alarm and/or annunciator provided in the main control room. 2.4.1 Hydrogen Injection Flow Control Parallel flow control valves should be provided in the hydrogen injection line, for system reliability and maintenance. If flow control is automatic, hydrogen flow rate should be controlled as a func-tion of plant process parameters such as steam or feedwater flow. The capability should be provided to adjust flow rate to each pump manually, if this is found to be necessary to achieve adequate hydrogen mixing in the recircu-l 1ation system. f Manual isolation valves shall be provided in each pump infection line to accom-modate pump-out-of-service conditions. I Individual pump injection lines should contain automatic isolation valves inter-j locked to the corresponding pump, so that hydrogen is not injected into a pump l that is not running. Provisions for shut-off of hydrogen injection shall be provided in the control room. 2.4.2 0xygen Injection Flow Control Parallel flow control valves should be provided in the oxygen infection line, for ~ system reliabtlity and maintenance. Oxygen flow rate shall be controlled to provide residual oxygen downstream of the recombiners. 2-7

e Design of system controls shall ensure that oxygen irdection continues after hydrogen flow stops. The purpose is to ensure that residual oxygen remains present after hydrogen infection ceases, so that all free hydrogen safely recombines. 2.4.3 Monitoring Provision shall be made to monitor continuously the concentration of dissolved In obtaining samples of recire water for this oxygen in the recirculation water. purpose, appropriate containment isolation shall be provided in accordance with 10 CFR 50, Appendix A, General Design Criteria 54, 55, 56, or 57. Provision should be made to monitor continuously the level of oxygen in the off-gas flow downstream of the recombiners.- d e 9 d e O e 1 2-8

t Table 2-1 RECOMMENDED HYDROGEN WATER CHEMISTRY SYSTEM TRIPS Limiting low power level per plant safety analysis (Control Rod o Drop Accident), if required by Tech Specs o SCRAM Operator request (manual) o Low residual oxygen in off-gas o High area hydrogen concentration o Low oxygen injection system supply pressure o Offgas ' train or recombiner tra'in trip o o High hydrogen flow Differential hydrogen vs. hydrogen infection o flow rate

• i Oxygen concentration in hydrogen compression o

module * -

• Electrolytic generation option.

l l l i l t 2-9 E

i Table 2-2 HYDROGEN ADDITION SYSTEM INSTRUMENTATION AND CONTROLS Portion of Parameter Measured or Hi gh Low Auto Overall System Function Performed Record Indicate Alarm Alarm Control Injection systems Hydrogen flow -(X) X Trip on high flow (H2 and/or 0 ) 2 Oxygen flow (X) X Offgas residual oxygen (X) X Trip on low oxygen I Recirc water dissolved oxygen (X) X X Area hydrogen concentration (X) (X) Trip l Isolate when Hydrogen injection line pump interlock pump is not in operation 4 X (X) Hydrogen supply Hydrogen storage tank level

• X Hydrogen storage tank pressure gauge
• X Hydrogen storage tank vacuum readout
• j X

Hydrogen gas supply pressure

• X J

Hydrogen gas storage temperature

• i X

X X Trip l Differential, hydrogen generation vs. hydrogen injection flow rate ** X X X Trip 0xygen concentration in hydrogen i compression module ** 2-10

. _ ~. - - ' ~~ Table 2-2 (Continued) HYDROGEN ADDITION SYSTEM INSTRUMENTATION AM) CONTROLS High Low Auto Pertion of Parameter Measured or Record Indicate Al am_ Alam Control Function Performed Overall System X (X)

• e Oxygen supply Oxygen tank level gauge X

Oxygen tank pressure gauge X 0xygen tank vacuum readout connection

• 1f this supply option is used "Fer electroytic generation option X

= required. (X) = recommended. e i b 9 a v 2-11 e

Section 3 SUPPLY FACILITIES a 1 3.1 GASEOUS HYDROGEN 3.k1 System Overview Hydrogen gas can be supplied from either permanent high-pressure vessels or from transportable tube trailers. For the permanent storage system, gaseous hydrogen is stored in seamless ASME-coded vessels at pressures up to 2,400 psig and ambient temperatures. The transportable DOT-coded vessels store hydrogen at pressures up to 2650 psig and ambient temperatures. With either storage design, the gas is routed through a pressure control station which maintains exiting hydrogen pres- ~ In any event, the gaseous hydrogen syst:m shall be provided by a supplier sures.

design, who h,as extensive experience in the Gaseous operation and maintenance of associated storage and supply systems.

hydrogen shall be provided per CGA G-5 and G-5.3. l; 3:1.2 Specific Equipment Description 3.1.2.1 Hydrogen Storage Vessels. The hydrogen storage bank shall be composed of ASME-coded gas storage vessels. Each tube shall be constructed as a seamless Specific tube design shall be based on ASME g f f vessel with swagged ends. Pressure Vessel Code, Section VIII, Division 1 and Code Case 1205. 4 The tube bank shall be supported to prevent movement in the event of line fa'il- ~ )li Each tube shall be equipped with a close-coupled shut off valve. Each bank ure. shall be equipped with a thermometer and a pressure gauge, as is necessary for proper filling. i 3.1.2.2 Transportable Hydrogen Storage Vessel. Transportable hydrogen vessels I shall be constructed, tested, and ratested (every 5 years), in accordance with specification, DOT 3A, 3AA, 3AX, or 3AAX. All valving and instrumentation shall be I identical to Section 3.1.2.1. i 3-1

The pressure' control station shall ba a mani-Pressure Reducino Station. The automatic reducing manifold 3.1.2.3 fold designed specifically for this installation. The discharge shall have two (2) full-flow parallel pressure reducing regulators.ti,fy s pressure range of these regulators shall be adjustable to injection requiremants. Sufficient hand valves shall be provided to ensu of the regulators. operational flexibility. diately down-An excess flow check valve shall be installed in the m t of a line stream of the regulators to forestall a hydrogen ld be set of the valves. between the maximum plant flow requirements and the full C break. y hion Tube Trailer Discharge' Stanchion.! A tube trailer discharge stan The stanchion consists of a 3.1.2.4 shall be provided for gaseous product unloading. flexible pigtail, shut-off valve, check valve, b d llision. convenience, and supported in a manner to minimize damage from a piping. l be A tube trailer grounding assembly for each d h provided. discharge of hydrogen begins. All equipment and interconnecting piping 3.1.2.5 Interconnecting Pipeline. following supplied with this system shall be installed in compliance with th standards: American National Standards Institute (ANSI) National Fire Protection Association (NFPA) 70, National Electrical Code. NFPA-50A, Bulk Hydrogen Systems. i All" applicable local and national codes. There are several suitable field installation tec industrial exphrience. connections: 1 l i 3-2

Copper-to-Copper, Brass-to-Brass, and Copper-to-Brass Socket 1 Braze J31nts. --Silver Alloy 45% Ag, 15% Cu, 16% Zn, 24% Cd., ASTM B260-69T and AWS A5.8-69T, BAG-1 Melting Range-Solidus-607.2*C Liquidus-i 618.3*C --Flux Working Range 593.3*C to 871.1*C 4 Copper Brass, Carbon Steel, and Stainless Steel N.P.T. i I Threaded Joints. i --TEFLON

• Tape SCOTCH ** Number 48 Tape l

or equal. -195.5'C to +204.4*C, O to 3,000 psig. Wrapped in i direction of threads. Flange Joints (On all Materials). l --Ring Gasket Material, Low Precut T.F.E. i Pressure (720 psig impregnated asbestos, + maximum) 1/16 inch thickness. Garlock 900 or equal. j -195.5'C to +168.3*C, ' O to 900 psig. --Ring Gasket Material, High FLEXITALLIC*** Type. Pressure Material to be 0.175 inch thick 304 stain-less steel with TEFLON filler and 0.125 inch carbon steel guide ring. l --Antiseize Compound For flange face, nut, and bolt lubrication. Halocarbon 25-55 grease or equal. -195.5*C to 'i +176.6*C, O to 3,000 psig. DO NOT USE ON ALUMINUM, MAGNESIUM, OR THEIR Ali.0YS UNDER CONDITIONS OF HIGH TORQUE OR SHEAR. 'I

• TEFLON is a trademark of E. I. duPont de Nemours & Co., Wilmington, DE 19898.

~

• • SCOTCH is a trademark of 3M Company, St. Paul, MN 55101.
  • FLEXITALLIC is a trademark of Flexitallic Gasket Co., Bellmawr, NJ 08031.

3-3

s Carbon Steel, Stainless Steel, and A1uainum Alloys Socket cnd Butt Welds. .l Metal Inert Gas, --Welding Procedure Tungsten Inert Gas, Metal Arc, or Plasma; with appropriate filler material and shielding gas. Proper surface and joint preparation (in regard to cleaning and clearances) should be exercised. All components that contact hydrogen must be free of 3.1.2.6 Component Cleaning. moisture, loose rust, scale, slag, and weld spatter; they must be essentia During system fabri-of organic matter, such as oil, grease, crayon, paint, ptc. cation, system components shall be cleaned to meet these objectives and th p l sealed to prevent contamination from dust and debris. 3.2 LIQUID HYDROGEN 3.2.1 System Overview Liquid hydrogen is stored in a vacuum-jacketed vessel at pressures up Based on data relating hydrogen injec-and temperatures up to -403'F (saturated). tion pressures to BWR plant power levels, hydrogen supply from a liquid sou be provided directly from a tank or pumped into supplemental gasous storage. l Gaseous storage requirements are identified in Section 3.1. ~ Factors such as the following should be evaluated to determine the proper d l of a liquid hydrogen system: \\ Feedwater pressure requireme'nts at the point of. hydrogen injection. Pressure losses from hydrogen supply system to feedwater injection point. Typically, feedwater pressure requirements must be such that hydrogen pressures directly from a liquid tank not exceed 120 PSIG. i In any event, the liquid hydrogen system shall be provided by a supplier w i design, opera-extensive experience in the i i 3,4 E

tion and maintenance of associated storage and supply systems, such as c Liquid hydrogen shall be provided in accordance with CGA G-5 and G-pumping. 3.2.2 Specific Equirpent Description Tanks for liquid hydrogen service, with capacities " 3.2.2.1 Cryogenic Tank. An " inner between 1,500-ga11ons and 20,000-gallons are similar in principle. 1 l vessel" or " liquid container" is supported within an " outer vessel" or " vacuum Necessary jacket " with the space between filled with insulation and evacuated. l piping connects from inside of the inner vessel to outside of the vacuum Gages and valves to indicate the control of hydrogen in the vessel are mo Legs or saddles to support the whole assembly are outside of the vacuum jacket. welded to the outside of the vacuum jacket. Tank Construction--Inner vessel's are designed, fabricated, tested, and stam f ~ accordance with Section VIII, Division 1 of the ASME Code for Unfired Pressure l For suitable liquid hydrogen vessel material CGA G-5 states that mate-Vessels. In addition to ASME Code rials must have good ductility at temperatures of-422*F. inspection requirements, 100% radiography of the inner vessel longitudinal l l-The tank outer vessel shall be constructed of carbon steel shall be completed. and shall not require ASME certification. Insulation--Insulation between inner and outer vessels shall be either perlite, The annular space should be evacuated to a aluminized mylar or suitable equal. j' j high vacuum (50 microns or less). Internal / external tank piping--Tank control piping and valving should be insta in accordance with ANSI B31.1 or B31.3. All piping shall be either wrought copper l. The following tank piping systems shall be subsystems. I' or stainless steel. Fill circuit, constructed with top and bottom lines so that the i' vessel can be filled without affecting continuous hydrogen l l supply. Pressure-build circuit, to keep tank pressures at operational levels. l Vacuum-jacketed liquid fill and pump circuits, where applisable. 3-5

i, Safety consideratian for the tank shall 3.2.2.2 Overpressure Protection System. be satisfied by dual full flow safety valves'and emergency backup rupture d of two sets of two (2) rupture disks and safety sue L. The primary relief systemAconsist [nterlockedbyatiebar Selector valves valves piped into separate " legs." With this arrangement, one safety so that one valve opens when the other closes. The dual primary relief valve and two rupture disks are available at all times. systems with 100% standby redundancy allows maintenance and testing t perfomed without sacrificing the level of protection from overpressure. i The safety valve shall be the primary relief device as specified by the Amer Society of Mechanical Engineers (ASME) Pressure Vessel Codes and is This valve shall be at 1.0 times the Maximum Allowable Working Pressure (MAWP). The rupture disk shall be sized to accomodate all " normal" overpressure demands. a " supplemental pressure relieving device" for " unexpected sources of e All The ASME code allows such devices to relieve at 211 above t heat." rupture disks on the tank shall be specified and purchased to burst at 1 Additionally, the tank shall be supplied with a secondary relief system not 1 The system shall be totally separate from.the primary required by the ASME Codes. It consists of a lock open valve, one rupture disk, and a secon-relief system. The rupture disk shall be specified and purchased to burst at dary vent stack. 1.33 MAWP. Supply system piping that may contain liquid and can be isolatable from All outlet connec-relief valves shall be protected with thermal relief valves. tions from the safety relief valves, rupture devices, bleed valves, and the fill line purge connections shall be piped to an overhead vent stack, per CGA C l Section 7.3.7. 1 Two lift-plate relief devices shall be installed in the tank's outer vessel to l relieve any excessive pressure buildup in the annular space. One shall be Two grounding assemblies shall be used to arrest static electricity. connected to the frame of the vessel and the other to the base of t Each shall be connected with bare wire to ground rods buried into the stack. Durin{unloadingoperation,theliquiddeliverytrailergroundwireshall earth. be clamped to the tank or vent stack ground wire (Reference CGA P-12). i i l 3-6

{* i Excess flow protection shall be added to the tank's liquid piping j ltd break would release a sufficient amount of hydrogen to threaten saf An acceptable methodology is identified in Section 4.3.2, Pipe The use of excess flow protection in conjunction with seismic pipe structures. this support from tank penetration to the excess flow assembly will arres Breaks." l 4 problem. The tank shall be supplied with a pressure gauge, a Instrumentation. These gauges are sufficient 3.2.2.3 liquid level gauge, and a vacuum readout connection. Instrumentation for r for normal monitoring of the tank condition. be ing, such as high/ low-pressure switches, pressure and level trans A complete listing of supply system instrumentation and control l added. identified in Section 2.4. e The liquid hydrogen pump shall be of Liquid Hydrogen Pump and Controls. t matic f 3.2.2.4 proven design to provide continuous hydrogen su l operation. 4 A positive isolation valve is used to i positive isolation valve. The valve shall 3.2.2.4.1 control the liquid feed into the pumping system per NFPA 508. The valve will only be open l be a failed-closed, pneumatically operated valve. during pump operation, closes in any fault mode, and can be remo i overridden in case of emergency. Although the system is protected by 3.2.2.4.2 System overpressure shutdown. i safety relief valves and rupture discs, system overpressure sh 7 by shutting down the pumps at high pressure. The temperature switch shall. con-4 Temperature indicating switch. 4 3.2.2.4.3 The tempera-f tinuously monitor the downstream gas line for low temperature. ture switch shall be provided to protect downstream equipment from temperatures. l A Pump operation is continuously monitored. i 3.2.2.4.4 Pump ooeration. cavitation condition or high or low temperature at the pump sha The remote control panel shall announce the fault by an, pump to t$ shut down. l audible alarm and light indication. l 1 3-7

3.2.2.4.5 Purging of controls. All electrical components in hydrogen service be designed in accordance with NFPA 70.' Nitrogen or air may be required set.A for purging pump motors, control panels and valves. 3.2.2.5 Interface with Gaseous System. Liquid hydrogen pump systems typically require a gaseous storage system as a surge or back-up to plant hydrogen supply. l These storage systems shall be designed in accordance with Section 3.1, GASEOUS HYDROGEN. Whenever a gaseous back-up is used in conjunction with a liquid hydro-gen system, an automatic switchover assembly shall be used to handle changes in l the supply of hydrogen. This assembly should use an adjustable pressure switch, an electric control panel, and two solenoid valves to allow hydrogen gas flow from .i the appropriate storage facilities. 3.2.2.6 Vaporization. The vaporization of the liquid hydrogen s m obe achieved by the use of ambient air vaporizers. '* 4 w * ~ M "' " *

• wJE@c" pousr.rrear wrr4 MuT The vaporizer should feature a star fin design and aluminum alloy construc-tion. For a combined iquid and gaseous storage system, the vaporizers used 3 *su-o l

have a design pressure The units are piped in parallel so that each unit can operate independently. Parallel vaporizer assemblies shall be sized for the hydrogen peak flow required for each plant and shall ' provide foe periodic intervals for defrosting as appropriate. i Ada For aAliquid only storage system, the vaporizer must withstand maximum pressures i generated from the cryogenic pump. These vaporizers shall be equipped with stain-less steel lining c>amduen ro 3.srors g. 1 l 3.2.2.7 Hydrogen Storage Vessels (Refer to Section 3.1 Gaseous Hydrogen) l 3.2.3 Site Characteristics of Gaseous and Liquid Hydrogen 3.2.3.1 Overview. Review of the following site characteristics shall be con-ducted by each BWR facility in locating the gaseous and/or liquid hydrogen supply ll systems: 1. Locating of supply system to exposures as addressed in NFPA 50A and 50B. l l 2. Route of hydrogen delivery on site. i I i 3. Location of supply system relative to safety-related equipment. 1 3-8

n, .c l .3.2.3.2 Specific Considerations. The area selected for liquid hydrogen system 3.2.3.2.1 Fire Protection. d siting shall meet or exceed all requirements for protection of pe d equipment as addressed in NFPA 50A and 508, gaseous and liq Each standard identifies the maximum quantity of systems, respectively. to hydrogen storage permitted and the minimum distance from hy j exposures. The need for additional fire protection for other than the hydrog shall be determined by an analysis of local conditions of hazard l l exposure to other properties, water supplies, and the probable 94 l NFM Sad em - effectiveness of plant fire brigades Av,f uo4uace w # m All l'1 quid hydrogen storage system installations shall I 3.2.3.2.2 Security. be completely fenced, even when located within the owner-contro h l. Lighting shall be installed to facilitate night surveillance. 3 Route of liquid hydrocen delivery on site. Each plant should determine the route to be taken by liquid hydrogen delivery truc 3.2.3.2.3 i In order to protect the hydrogen storage area from l site and off-site areas. l any vehicular accidents, truck barriers shall be installed around th l, perimeter of the system installation. l 1, Within the security area all deliveries are controlled by plant securit personnel, per the requirements of 10 CFR 73.55. Each Location of storace system to safety-related' structures. i t 3.2.3.2.4 plant shall determine that the location of the liquid hydrogen st l li is acceptable considering the hazards described in Section 4.2. ) t o } l i I 1 3-9

3.3 ELECTROLYTIC System Overview 3.3.1 _ f obtaining The disassociation of water by electrolysis is an acceptable me the gases needed for hydrogen water chemistry. The electrolytic gas gases can be conveniently generated at the rate used.i l appli-generator can bo proven equipment the same as used in other ind Depending on the generator operating pressure, either hydroge hydrogen pressors or pressure breakdown (control) is utilized to m cations. injection pressure requirements. d maintenance a supplier who has extensive experience in the design, operation an of these systems. Specific Equipment Description _ ~ 3.3.2 h Equipment and processes associated with the electrolytic me rectifiers, the electrolytic cells, scrubbers, compressors, a HWC gases include piping, valves and associated controls. 1 Gas Generator _ h Water is disassociated into hydrogen and ongen in the electrolytic The water flows into the direct current electricity provided by the rectifiers. cells, at the rate dissociated, where it forms a ' solution with the e Hydrogen used to carry the electrical current from one electrode to the other. is formed at one electrode and oxygen at the other, which is dependen The electrodes are separated which keeps;the gas bubbles current direction. separate as they rise to the collection outlets of the cells. Vessels _ Unless exempted because of size (smaller than 120 gallons of wat (less than 15 psig), for industrial safety reasons, the requirem American Society of Mechanical Engineers (ASME) Boiler and 4 Section VIII, Division I shall apply to the design and constructio The code desi< n pressure and temperature shall be selected to b highest pressore and temperature that can be reached during ope 1 3-/O

.__._.,........y ~. Piping Piping and related equipment shall conform to the American National Standard Code (ANSI) for Piping B31.1 or B31.3 except that non metallic-materials may be used in low pressure applications if supported by experience and/or tests which have demonstrated their suitability for the service conditions, and operating pres-sure and temperature conditions are within the material manufacturer's specifications. Valves Valves should be designed such that the prevention of hydrogen leakage into an enclosed area does not rely on a single packing. Valves in any portion of l the hydrogen flow path that is at subatmospheric pressure should be designed for zero inleakage of air. Welded connections shall be used on all hydrogen piping that may operate below P atmospheric pressure. The oxygen flow path, including valves, shall not contain combustible greases, including traces of oils, or other combustible materials not demonstrated by long usage to not ignite at the conditions of temperature and velocity. Valves in the hydrogen flow path in or downstream of any point where the pres-i sure can be below atmospheric si:ould have spark resistant' rubbing and impacting surfaces if the rubbing or impacting velccities can exceed the spark threshold, i l A helium leak test shall be performed to assure a leak tight system after installation. Compressors If a mechanfcal method of gas compression is employed, it should be located at the gas supply facilities. A gas pressurization method may be employed which does not require mechanical compressorsand which pemits gas generate at a rate equal to gas usage, thereby avoiding the need for gas storage volume to match the difference in duty between the gas generator and the use rate. However, if a mechanien1 compressor is used, it shall meet the following requirements: The pressure gr.dient at any seal should be outward whenever the compressor 5-D\\

~ The shaft seal leakage shall not discharge into any enclosed contains hydrogen. space that is not either continuously purged with an inert gas or ventilated to avoid an explosive mixture of air and hydrogen assuming the rehotential The compressor shall not introduce'1inacceptable. rate of shaft seal leakage. The compes-levels of organics and/or fluorides / chlorides into the hydrogen. sor shall be designed to permit purging of all compartments before and after i maintenance. Where gas storage volumes are employed, their size should be minimized. Where practical for the application, a type of compressor should be used that i i does not require surge tanks. Gas Generator Shelter Passive ventilation shall be provided for the gas generating room of the equip-Inlet openings shall be provided at floor level in exterior walls ment shelter. Inlet and and outlet openings shall be located at the high point of the room. outlet openings shall have an arrangement and sufficient area to assure fault-free passive ventilation. The discharge from outlet openings shall be directed to a location that has no ignition sources. The gas generating room of the shelter shall be partitioned away from all other The rectification equipment shall be rooms that could contain ignition sources. partitioned away from the gas generation equipment. I Equipment for space heating of the gas generating room shall not contain any ignition sources and shall not allow gases, including air, to pass out of the l room to an ignition source in a heating syste:n. I Windows and doors shall be in exterior walls only. Windows shall be made of shatterproof glass or plastic in metal frames. The shelter shall be of non-combustible materials (except for the transparent materials used in windows). O . 3-/L.

i I 3.4 LIQUID OXYGEN System Overview 3.4.1 Liquid oxygen is stored in a vacuum-jacketed vessel at pressures Oxygen is taken from the vessel and andtemperaturesupto-251*F(saturated). The " warmed" oxygen is routed thro vaporized through ambient air vaporizers. N case 6 pressure control station which maintains exiting oxygen gas pressu The liquid oxygen system shall be provided by a supplier who has design, operation 44d e. extensive experience in the Liquid oxygen shall be and maintenance of associateo storage and supply systems. provided per CGA G-4 and G-4.3. 3.4.2 Specific Equipment Description Tanks for liquid oxygen service, with capacities between 3.4.2.1 Criogenictank. An " inner vessel" or 3,000 gallons and 11,000 gallons are similar in principle. " liquid container" is supported within an " outer vessel" or " vacu Necessary piping connects

• os v?w SeMer de7wem) m e -n a us.

Gages and valves ntse.*nou from inside of the inner vessel to outside of the vacuus jacket. to indicate the control of product in the vessel are mounted outside of th 3 83

Legs or saddles to support the whole assembly are welded to the outside jacket. ~ of the vacuum jacket. Tank Construction--Inner vessels are designed, fabricated, tested and stamped in accordance with Section VIII, Division 1, of the ASME Code for Unfired Pressure For suitable liquid oxygen vessel materials, CGA G-4 states that mate-Vessels. The outer rials must have good ductility at cryogenic temperatures of -300'F. l vessel is constructed of carbon steel and does not require ASME certification. Insulation--Insulation between inner and outer vessels shall be either perlite, i aluminized mylar or suitable equal. The annular space should be evacuated to a high vacuum (50 microns or less). Internal / External Tank Piping--Tank control piping and valving should be installed j in accordance with ANSI B31.1 or B31.3. All piping shall be either wrought copper or stainless steel. The following tank piping systems shall be subsystems: Fill circuit constructed with top and bottom lines so that the l vessel can be filled without affecting system operation. Pressure build circuit, to keep tank pressures at operational lI levels. Economizer circuit, to preferentially feed oxygen gas from vessel vapor space to process. Since the analysis assumes the vapor cloud originates from the tank location, the tank i, and its foundation shall be designed to remain in place during the design basis tornado. 3.4.2.2 Overpressure Protection System. Safety consideration for the' tank shall i l be satisfied by dual full flow safety valves and emergency backup rupture discs. f The primary relief system shall consist of two sets of one (1) safety valve andThis one (1) rupture disc piped into separate legs, coupled by a three-way valve. I dual primary relief system with 100% standby redundancy a11oss maintenance and testing to be performed without sacrificing the level of protection from j[i overpressure. .The safety valve shall be the primary relief device as specified by the American SocietyofMechanicalEngineers(ASME)PressureVesselCodesandissettorelieve I at 1.0 times'the Maximum Allowable Working Pressure (MAWP). This valve shall be { sized to accommodate all " normal" overpressure demands. The rupture disk shall be a "supplementa.1 pressure relieving device" for " unexpected sources of external >j All heat." The ASME code allows such devices to relieve at 21% above the MAWP. rupture disks on the tank are specified and purchased to burst at 1.2 MAWP. 3-M

Annular space safety heads shall be provided to relieve any excess positive pres-sure buildup, which might result from a leak,in an inner vessel. Supply system piping that may contain liquid and can be isolatable from the tank relief valves shall be protected with thermal relief valves Instrumentation--The tank shall be supplied with a pressure gauge, a liquid level gauge, and a vacuum readout connection. These gauges are sufficient for normal monitoring of the tank condition. Instrumentation for remote monitoring, such as A com-high-low-pressure switches, pressure and level transmitters may be added. plete listing of supply system instrumentation and control is identified in l Section 2.4. 3.4.2.3 Vaporization. The vaporization of the liquid oxygen shall be achieved by the use of ambient air vaporizers. 1 The vaporizer should feature a star fin design and extruded aluminum alloy con-l l The l struction. The design pressure of these units shall be at least 300 psig. use of mulitiple vaporizers, piped in parallel and sized to handle peak plant flow J l requirements should be considered. 4 3.4.2.4 Pressure Control Station. The pressure control station shall be a l manifold designed specifically for this installation. The automatic reducing The manifold shall'have two (2) full-flow parallel pressure reducing regulators. discharge pressure range of these regulators shall be adjustable to satisfy plant oxygen injection requirements. Pressure gauges shall be provided upstream and downstream of the regulators. Sufficient hand valves shall be provided to ensure complete operational flexibility. Protection from low oxygen temperatures shall be included in the system design. f 3.4.3 Materials of Construction for Oxygen Piping and Valves The design and installation of oxygen piping systems shall be in accordance with the latest ANSI B31.1 or 831.3 code and the following guidelines for material selection for oxygen systems. l 3-IS

Observations of past exygen fires indicate that ignition can occur in carbon steel Fric-and stainless steel piping systems operating,at, er near, sonic velocity. F tion from high velocity particles is considered to be the source of ignition. Copper, brass, and nickel alloys have the characteristic of melting at tempera-This makes them extremely resistant tures below respective ignition temperatures. to ignition service, and once ignited, they exhibit a much slow r rate of bur 61ng than carbon or stainless steels. i I As a result of these observations, the following materials, in order of prefer-l ence, are acceptable for oxygen service. In the case of carbon steel or stainless steel, the maximum velocity of gaseous oxygen must be within guidelines estab-11shed by the Compressed Gas Association CGA Pamphlet CG-4.4, " Industrial Practices For Gaseous Oxygen, Transmission and Distribution Piping Systems." Copper Brass Monel 1 Stainless Steel i Carbon Steel If steel pipe is used and some local flow conditions cause the velocity to exceed that established in CGA G 4.4, then that portion of the system must be converted to a cofa-base alloy and extend a minimum of 10 diameters downstream of the i These local flow conditions may occur jl point of return to the allowable velocity. ll at control valves, orifices, branch line take-off points, and in the discharge piping of safety relief devices. Valves that open rapidly are not suitable for oxygen service,' since rapid fillin 'l f of an oxygen line will result in a temperature increase due to adiabatic compres-As a result of this phenomenon, ball valves and automatic valves have the j sion. l following restrictions: Valve bodies shall be made of a copper alloy. Balls shall be monel or brass. Valve seats and seals should be teflon, non-plasticized Kel-F, Kalrez, or Viton. Ball valves may not be used as process control valves in Ball valves ~may be used as = throttling or regulating service. isolation valves, emergency shutoff valves, or vent or bleed valves where they are either fully open or fully closed. 3- /G l

-.c Pneumatic or electric ball valves used fer on-off services shall have an actuation time from fully,c1csed to fully open of No restriction is ag. dd * ~~~ T seconds 1for pressures up to 250 psig. placed on actuation time from fully open to fully closed. g,, Piping imediately downstream must be a straight run of copper-bearing material for a minimum of 10 diameters. gg_ _

• Pneumatic or electric ball valves used for emergency service may be fully open or fully closed to the emergency position, with no restrictions on actuation time.

Suitable valve packing, seats, and gasket materials are listed below in order of preference from the oxygen compatibility basis only. Teflon Glass-filled Teflon Nonplasticized Kel-F Garlock 900 Viton or Viton A /N A CCOdkwcc w em (64 g j 3.4.4 0xygen Cleaning ygen shall be All piping, fittings, valves, and other material which may contact Observa-cleaned to remove internal organic, inorganic, and particulate matte tion has shown that ignition can occur in properly designed piping systems when foreign matter is introduced. Therefore, removal of contaminants such as grease. oils, thread lubricants, dirt, water, filings, scale, weld spatter, paints, or l Cleaning should be accomplished by preclean-c other foreign material is essential. ing all parts of the system, maintaining cleanliness during construction, and by completely cleaning the system after construr. tion. i 3.4.5 Site Characteristics of Liquid' Oxygen Review of the following site characteristics shall be 3.4.5.1 Overview. completed by each BWR facility as part of their efforts to locate the liquid l [ oxygen storage system. Location of supply system to exposure as addressed in NFPA 50. i 1. 2. Route of liquid oxygen delivery on site. Location of supply system relative to safety related equipment. 3. 4, Loennos) 01-Hvneoenors w4Ce. t i J s 3-17

_ _.. ~. 3.4.5.2 Spacific Ctnsiderations. The area selected for liquid oxygen system siting 3.4.5.2.1 Fire protection. shall meet or exceed all requirements for protection of personnel and equipment as addressed in NFPA 50. Bulk 0xygen Systems. The The standard identifies the types of exposures under consideration. number of exposures warrants a plant-specific review for proper code compli-As much separation distance as practical should be provided between ance. the hydrogen and oxygen systems. 3.4.5.2.2 Security. All liquid oxygen supply system installations shall be completely fenced, even when located within the security area. Lighting shall be installed to facilitate night surveillance. 3.4.5.2.3 Route of liquid oxygen delivery on site. Each plant should determine the route to be taken by liquid oxygen delivery trucks through on-and off-site areas. In order to protect the oxygen storage area from any vehicular accidents, truck barriers shall be installed around the perimeter of the system installation. Within the security area all deliveries are controlled by plant security personnel, per the requirements of 10 CFR 73.55. 3.4.5.2.4 Location of storage system to safety-related equipment. Each plant shall determine that the location of the liquid oxygen supply system is acceptable considering the hazard described in Section 4.4. 3.4.6 Properties of Liquid Oxygen Liquid oxygen is pale blue in color, extremely cold, and nonflammable. Oxygen supports life. It readily combines with other elements. It is a strong oxidizer. and an oxidize.r is necessary to support combustion. I 3-IS

~MateriaYswhich ' Oxygen will react with nearly all organic materials and metals. Equipment used in burn casily in air usually burn more vigorously in exygen. oxygen service must be designed to utilize materials that have high ignition temperatures and are nonreactive with oxygen under the service conditions of the contemplated system. O e l i i i 9 4 { O i l O I 3-/p t i i -

L. T..._..- r o i o. Section 4 SAFETY CONSIDERATIONS i 4.1 GASEOUS HYDROGEN (LATER) i 4.2 LIQUID HYDROGEN 4.2.1 Properties of Liouid Hydrogen Hydrogen is colorless as a liquid. Its vapors are colorless, odorless, tasteless, and highly f1ammable. i t'

p ' Liquid hydrogen is noncorrosive, and therefore, special materials of construction are not required. However, because of its extremely cold temperature, equipment must be designed and manufactured of material which is suitable for extremely low temperature operation.

The following identifies the properties of liquid hydrogen: Mol e cul a r We i ght................................................ 2.016 l Boil i ng P oi nt 9 1 a tm.................................-4 23.0F -252.8C) F re ezi ng Poi nt 9 1 atm................................-434.5F -259.2C,)) -239.9C Cri tical Tempe rature..................................-399.8F Critical Pressure.................................. 188 psi a (12.8 a tm) Density, Li qui d 9 B.P., I atm........................ 4.4 23 l bs./cu. f t. Spdgi fi c Gravi ty, Li quid 9 B.P., I atm.......................... 0.0710 S pe ci fic Vol ume 9 68F (20C), 1 atm................... 191.3 cu. f t./l b. 4 Latent Heat of Va pori zati on........................... 389 Btu /l b. mol e Flammable Limits 91 atm in air.............. 4.00% - 74.2% (by volume)) Flammable Limits 91 atm in oxygen........... 4.65% - 93.9% dbyvolume, Detonabl.e Limi ts 9 1 atm i n ai r.............. 18.2% - 58.9% by volume Detonable Limits 91 atm in oxy 9en...............155 - 90% ((by volum Autoignition Temperature 9 1 atm........................... 932F (5000) i Expansion Ratio, Liquid to Gas, P.B. to 68F (20C).............1 to 848 Spec Gravity, Sat. V apo r 9 B.P.................................... 1.12 f 4-1

...... ~ ..c . ~...- I 4.2.2 Storage Vessel Failure i For this report, storage vessel failure is defined as a large breach resulting in It is assumed that the rapid emptying of the entire contents of liquid hydrogen. the tank is full at the time of failure and that the entire spill vaporizes The following enumerates potential causes of vessel failure and instantaneously. the required design features that mitigate or alleviate these potentials. i Seismic The tank and its foundation shall be designed to meet the seismic criterion for I critical structures and equipment at the plant site (i.e., design basis l' earthquake). j' i Tornado and Tornado Missiles The tank and its foundation shall be designed to withstand the " design basis As a minimum, the tornado characteristics" as outlined in Regulatory Guide 1.76. tank shall remain in place so that any liquid spillage will originate.from the 2 tank location. Design basis tornado-generated missiles are capable of breaching all known 4 1 commercially available liquid hydrogen storage vessels. Therefore, tornado l' missiles are a potential cause of " storage vessel failure.", i i Aircraft A large aircraft crashing directly into the storage area is'. capable of breaching all known commercially available liquid hydrogen storage vessels. Therefore, aircraft crash is a potential cause of " storage vessel failure." i Fire The overpressure protection system shall be sized to accommodate the worst-case !i vaporizatiori rate caused by a hydrocarbon fire engulfing the outer shell with loss ll of vacuum and hydrogen in the annulus of the double-wal'1 storage tank (as per CompressedGagAssociation5.3andASMESectionVIIIrequirements). l 1 4-2 l

., 1 M.~. ai eAM yy % -ci 1 3 APPENDIX A 5.,, g.o a r:5. ASD REGULATIONS APPLICABLE ,,. "f G'E' CHEMISTRY INSTALLATIONS v- %, ev.<. ' i i n.e,s, ste-et es, and regulations which may be applicable to

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' s t ry i ns t al la t ions. t e.te es *: Protection Against Radiation

a s r-t.'* rre-t e' haltf tcation of Electric Equipment Important to at : e 1: si ta'e p f: nxiear Power Plants s;.

.. s, cc-+ral Design Criteria for Nuclear Power Plants, 5,..,,- v.,,,

,s g Cetteria 54, 55, 56, or 57.

e. s.t. ,r. is f r Physical Protection of Licensed Activities in s :s*: 1: s.r 'e e t cw Fractors Against Radiological Sabotage l p e,,: us. t'te Cr1terts e*,.s re sith St anda rds p y, :: : t e r. y e e :r i ::- e,e p se e s ; r i : t.

., 3..

ma c e. =- e. ':. e* t e.t ro rvet - Enviromental Radiation Protection t'e ta :t fc axlear Power Operations eder er .= *.n ie, sene' C c se, Sect ion VIII, Pressue Vessels one t-w e-,.iv e set se' Code, Section IV, Heating Boilers { ess F e.e e we eeue' Ce4e, Sect ton II, Welding and Brazing new aw. GM D' 3 eme*tse Est tra? StaMards Institute, Power Piping em era nie..... eeu w.e? Ste*dards Institute, Chemical Plant and ev. *u se t ee ry P i pi ng a a & M.* e, ser * **,.,**. t e

• S t r s, Spec i f i cat i o n fo r

$.{ h e 86 * 's t tee'ee* e g boet sitte Materials for Oxygen Service a W W EA be 'r e*4 taastwies of Large, Welded, Low-Pressure Storage

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J ~.__ e. r Structural Welding Code AWS DI.1 Bulk 0xygen Systems NFPA50 Gaseous Hydrogen Systems at Consumer Sites NFPA 50A Liquified Hydrogen Systems at Consumer Sites NFPA 508 National Electrical Code NFPA 70 Compressed Gas Association G-4, Oxygen Compressed Gas Associated G-4.1 Cleaning Equipment for Oxygen Se j Compressed Gas Assocation G-4.3, Cmanodity Specification for Oxygen Compressed Gas Association G-4.4, Industrial Practices for Gaseous Oxy I Transmission and Distribution Piping Systems Compressed Gas Association G-5, Mydrogen Compressed Gas Association G-5.3, Commodity Specification for Hydroge Compressed Gas Assocation P-12, Safe Handling of Cryogenic Liquids U.S. Army Technical Manual TMS-1300 U.S. Department of Transportation Specification 3A, 3AA, 3AX, 3AAX !. s U.S. Nuclear Regulatory Commission Regulatory Guide 1.76, " Design for Nuclear Power Plants" U.S. Nuclear Regulatory Conmission Pagulatory Guide 8.'8, Information R Ensuring that Occupational Radiation Exposures at Nuclear Power Be As Low As Reasonably Achievable (ALARA)" U.S. Nuclear Regulatory Commission Regulatory Guide 8.10. " Operat for Maintaining Occupational Radiation Exposures As Low As Reasonably 1! Achievable" s i I e t l ? - S

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Flood The following flood conditions could result in vessel failure: High water reaches the top of the vent stack for the o overpressure protection system. High flood velocities dislodge the tank. o Under either condition, water could enter the vent system and defeat the overpressure protection system. Therefore, the tank shall be located such that maximum flood heights cannot exceed the vent stack elevation and that high flood velocities cannot occur. Vehicle Imoact The storage vessel shall be protected from the 1,mpact of a large vehicle (e.g., semitrailer truck) by a barricade capable of stopping such a vehicle. Structural Vessel Failure The storage vessel shall be designed, constructed, inspected and operated to assure an extremely low likelihood of structural tank failure during its tenure on site. A vessel designed in accordance with this document complies with this low probability requirement. 4.2.2.1 Fireball. For the two potential causes of " storage vessel failure," ~ tornado missiles and aircraft impact, a fireball at the tank location is the expected result. The major reasons for this is the high ignitability of hydrogen and the density of ignition sources in the aftermath of these causal events. ~ Details of these considerations are given in reports for the Dresden plant (Reference 4,-1). The themal flux versus distance from the fireball center (tank location) is shown on Figure 4 I for the range of commercially available tank sizes. The durations of the various fireball sizes are also given. These fluxes and durations will not adversely affect equipment or personnel enclosed in the concrete / steel safety-related struqtures. However, each utility shall review any unique site characteristics to assure all safety-related equipment will function in the event of a fireball. 4-3 L

Figure 4-1 Th;rmal Flux vs. Distance from Fireball Center i t t 1 l I I a a .. ___ _ _ _ y _.. ___ __._ i _4 -__ y 4 i -;q _______a.._._.._ __4._..__ _ d i ___ i <i i l j 1 - ... j -).- ~. 2 : : : n e i KEY Tank Size, gal. Fireball Duration, sec j 2 O 20,000 8.18 1 l l 18,000 7.90

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t .o 4 l 4.2.2.2 Explosion at Tank Site. For the instantaneous release of the entire tank contents, the following were used to determine blast parameters for an explosion at the tank site: i l 1. Gaussian F weather stability 2. Detonation limits of hydrogen,18.3-59% l 3. TNT - hydrogen equivalent of 20% on an energy basis (520% on a massbasis) 4 The above results in an equivalence of 1.37 lbs of TNT per gallon of tank size. Using this conversion factor and U.S. Army Technical Manual TM5-1300, blast l overpressures and impulses can be calculated as a function of distances from the site for any size of tank. t ] These blast parameters could then be compared to the dynamic strength of safety-related structures. This concept of dynamic response strength of structures is illustrated on Figure 4-2 for the threshold of partial demolition of residential brick construction. This curve represents many " data points" for homes damaged j during World War II from known size bombs at various standoff distances. Brick ) butidings subjected to incident impulses /overpressures to the right and above this l curve will receive more severe damage. Points to the left and below the curve will be under the threshold for this damage criterion. In order to determine the j required separation distances, similar curves to this could be generated for l specific related structures at each nuclear power plant. As an alternative to { individual strength calculations, it would be conservative to assume that the heavily reinforced concrete safety-related structures could withstand the blast i parameters for this damage criterion. Further discussion of this criterion can be j: found in reference 4-1. l i Therefore, the minimum required separation distances from the storage tank to i safety-related structures or equipment for the event of an explosion at the tank l ' site shall meet the criterion depicted on Figure 4-3. Alternatively, a dynamic strength analysis may be performed for a specific safety-related structure if j closer siting is desired. 1 i e-l 4 I 4-4 -.-.--nw--.-,-,,-.,.,-..

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.o 4.2.3. Pipe Breaks t This section addresses the requirements for gaseous and liquid hydrogen piping l systems attached to the storage vessel up to the point where excess flow i I protection is provided. The criteria for acceptable siting for the event of a pipe break are: 1. Dilution of resultant release below the lower flammability limit of 4% before reaching safety-related air intakes. j 2. Maximum overpressures below the blast damage criterion outlined in Section 4.2.2. j It is conservatively assumed that all releases occur while the storage vessel is i at 150 psig. This is the maximum allowable working pressure of the majority of c j commercially available tanks. Gaseous Piping I Gaseous releases at elevated pressures result in supersonic jet velocities _and a dispersion process that is momentum-dominated. Under these conditions', the Gaussian dispersion model unrealistically overestimates the amount of hydrogen in the explosive region and the distance to the lower flammable region. Therefore, these properties of gaseous releases were calculated using a jet dispersion model described in Reference 4-1. The results of this modeling are shown in Figure 4-4 as minimum separation distances between safety-related structures and air intakes versus hole size or inside diameter of the pipe. Each utility shall detemine that the storage vessel piping and location meet these minimum requirements or show that less stringent I criteria should be applied to a specific case. An example of such an exception would be if the air intakes have automatic shutters controlled by hydrogen analyzers thus preventing the ingestion of a flammable mixture. 1 Licuid Piping l The vapor cloud formed by the flashing and rapid vaporization of a liquid release is nearly neutrally buoyant and has little momentum associated with its ) fomation. linder these conditions, it is appropriate to use the continuous Gaussian dispersion model. It is conservatively assumed that liquid discha-oes i will instantaneously vaporize. 3 l f 4-5

Figure 4-4 Mintum Required Separattn Distance vs. Hole Size a d ID of Pipe for Gaseous Releases from 150 psi Liquid Hydrogen Storage Tank

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4 .i 1 The minimum required separation distances to safety-related structures and air intakes, using the above assumptions, are given on Figure.4-5 as a function of i 4 discharge rate. These distances shall be app;ied to all liquid piping, including those from any pump discharges, that are not seismically supported or protected by j l excess flow devices. For convenience, hole size or inside diameter of pipe for I the worst-case break geometry is also plotted on Figure 4-5. I l 4.3 ELECTROLYTIC 4.31 General i I The electrolytic supply option need not constitute storage of hazardous matert'als f on-site if it operates at approximately atmospheric pressure and involves the storage of no more than 2500 scf of hydrogen and 1250 scf of oxygen. If these limits are met, and the system is designed as described in Section 3.3, it need j only be analyzed as described below. Other system designs have not yet been considered. Compressed gases utilized in conjunction with electrolytic systems shall be in accordance with Sections 3.1 and 4.1. 1 l Events important to industrial safety (abnormal transients., accidents and external 1 l events) must be evaluated to identify those which could result in any of the [ following conditions: 1. Hydrogen accumulation to a combustible mixture in an enclosed j space. 2. Air or oxygen mixing with hydrogen within electrolytic systen components. l 3. Hydrogen fires. 1 i When the potential exists for the above undesired conditions to occur, appropriate I mitigating features shall be incorporated in the design or operation of the system ) or the consequences with respect to plant and personnel safety shall be evaluated I or determined to be acceptable. I J I 4.3.2 Purity of Gases l The gases as, collected from the electrolytic cells in a well working system will i be over 995 pure and concentration of the oxygen in the hydrogen stream and the j i concentration of hydrogen in the oxygen stream will be well below the ignition limits. However, over time, purity may tend toward acceptable limits due to the i build up of oxides or contaminants on the electrodes. This trend is a very slow process detectable by periodic purity testing well before combustible mixtures are 4-6

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.a reached. The time that it takes depends on materials of the electrodes, and impurities in the water. To monitor cell performance and avoid combustible mixtures, gas purity shall be periodically or continuously measured. As a second j f precaution against an unsafe condition, the equipment shall be designed to contain i an internal explosion. 4.3.3 Air Inleakage 4 The electrolytic cells and their gas collection headers shall be controlled to a pressure above atmospheric. f Since nearly any method of compression will cause a reduction of pressure at the inlet of the compression device, the equipment at and between the pressure j regulating device (for maintaining the gas generator pressure) and the compressor i must be designed to avoid air inleakage. This equipmept shall be designed to (1) not contain sufficient hydrogen to represent a hazard to plant safety, (2) nota have any ignition sources in the hydrogen flow path, and (3) avoid combustible gas l mixtures. Valves in this flow path should have spark-resistant seat and sten l gut' des. The design should be capable of containing an internal explosion. 4.3.4 Out Leakage The systen must be designed to avoid combustible gas mixtures which could result from unintentional outleakage. Controlled venting to safe locations in the atmosphere is acceptable. 1 The kindling tenperatures of combustible materials decreaselwith increased concentrations of oxygen. Therefore, oxygen must not be vented in the vicinty of combustible materials that would be at temperatures above the kindling tenperature j in a pure oxygen concentration. t I 4.3.5 External Events External ev'ents such as seismic, tornado, aircraft crash and flood cannot result l in consequences more severe than cited above and need not be considered further. f i i 4-7 1 . ~. - - -.-

I l 4.4 LIQUID OXYGEN i 4.4.1 Liquid Oxygen Storage Vessel Failure The liquid oxygen storage vessels are vulnerable to the same potential causes of failure as the liquid hydrogen vessels but the consequences of failure are much The potential threat from a liquid oxygen spill is the ingestion of less severe. If this were to occur, the oxygen-enriched air into safety-related air intakes. i f effective combustibility of ignitable materials in the enriched area would For the purpose of this report, it is conservatively assumed that total increase. in air + 9% enriched 0 ) "III f oxygen concentrations above 30 vol. % (21% 02 2 increase the effective combustibility of ignitible materials in the area. 4.4.2 Liauid Oxygen Vapor Cloud Dispersion The instantaneous vapor cloud fomed by a large liquid oxygen spill will have a density of 3.59 relative to air. Such a cloud will experience considerable This gravity-driven slumping as it disperses and translates with the wind. l process has been described by the DEGADIS model developed by Prof. J. A. Havens of 4 the University of Arkansas. His model has been found to agree well with published data on large releases of dense gases conducted by the U.S. Department of Energy, U.S. Coast Guard and others. The DEGADIS model has been used to determine the height of the vapor cloud as a function of distance for various sizes of commercially available liquid oxygen f storage tanks. It was conservatively assumed that any vessel failure would result f in the instantaneous vaporization of the entire tank content's. Figure 4-6 shows the results of this study for the worst-case weather conditions of F stability and l a 10-meter per second wind speed. For dense gas dispersion, lower wind speeds result in more radial spreading with a lower cloud height and shorter maximum drift distance'. Higher wind speeds will translate even the largest release past I l safety-related intakes in less than 10 seconds, giving little time for ingestion of enriched air. Therefore, liquid oxygen storage vessels shall be located such that safety-related air intakes are within the acceptable region defined by Figure 4-6 or alternative I analyses shall be performed to justify the location. 4-8 L_.______,___

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4.5 REF ERENCES 4-1 Air Products document, later O e 6 i l I l 4-9

e l I Section 5 i VERIFICATION I The various methods of verifying the effectiveness of HWC (i.e. electrochemical i potential, constant extension rate tests, etc.) are not within the scope of this Appropriate methods of verification should be selected and implemented i document. on a plant specific basis. 0 I e n i I l l j I J f 5-1

~ I Section 6 OPERATION, MAINTENANCE, AND TRAINING 4 This section gives recommendations to the operating utility for operation, main-tenance, and training in order to meet the design intent of the hydrogen water chemistry (HWC) system. The operation of a HWC system will require operator and chemistry personnel attention, which will increase their work load. Because of the radiation increases that this system causes, an awareness of ALARA principles is required by all plant personnel. This system could also have an effect on the off-gas system and the plant's fire protection program. 6.1 OPERATING PROCEDllRES Written procedures describing proper valving alignment and sequence for any anti-cipated operation should be provided for each major component and system pro-Check-off lists should be developed and used for complex or infrequent cess. modes of operation. Operating procedures should be considered for the following operations: 1 1. Hydrogen addition system startup, nomal operation, shutdown and alann response i 2. Material (gas or liquid) handling (filling of storage tanks) operations which are consistent with the supplier's recommendations 3. Purging of hydrogen and oxygen lines i 4. Operation of on-site gas generation systen (if appropriate) 5. Fire protection or safety measures for hydrogen or oxygen enhanced fires and hydrogen or oxygen spills. 6. Calittration and maintenance procedures as recommended by equipment or gas suppliers 7. Routine inspection of HWC system equipment ) 6-1

1, j i i i Adjustment of the main steam line radiation monitor setpoints (if 8. i i appropriate). 1 6.1.1 Inteeration Into Existine Plant Doeration Procedure 1 Where appropriate, operation of the NWC syste shall be incorporated into nomal j j plant procedures such as plant startup and shutdown., t 6.1.2 Plant-Soecific Procedures l Appropriate procedures shall be developed to provide guidance for plant operators j when operation of the NWC system necessitates operation of an existing system in a Areas which should be considered are: j different mode or raises new concerns. i 1. Operation of the off-gas system 2. Possible off-gas fires 6.1.3 Radiation Protection Procram \\ j 0peration of a HWC systa results in an increase in radiation wherever nuclear r 1 The radiation protection program shall be reviewed aiwi appro-4 steam is present. I priate changes made to compensate for these increased tadiation levels. The following guidelines are established to ensure that radiological exposures to 5 both plant personnel and the general public are consistent with ALARA require-Compliance with these requirements eliminates all radiological significant l l sents. safety hazards associated with HWC implementation. The operation of a hdrogen addition system may at some plants have a slight effect on the off-gas delay time I due to the excess oxygen added. This may slightly increase plant effluents and l j i should be reviewed. However, since the design objectives and liiniting conditions l i for operation as defined by 10 CFR part 50, Appendix 1, are not impacted, no j l Appendix ! revision is required. i i permanent hydrogen water chmistry systems and j 6.1.3.1 ALARA Commitment. programs will be designed, installed, operated, and maintained in accordance with l t l the provisions of Regulatory Suides 8.8 and 8.10 to assure that occupational l radiation. exposures and doses to the general public will be "as low as reasonably i i achievable."- i l t 6-2 i

6.1.3.2 Initial Radioleical Survey. prior to long-tern hydrogen irdection, a comprehensive radiological survey should be performed to quantify the 1spect of hydrogen water chenistry on the environs dose rates, both within and outside the plant. This survey should be used to determine if signficant radiation changes occur in restricted areas and at the site boundary. gased upon the magnitude of the change, it should be deterwined if new radiation areas or high radiation areas need to be created. Appropriate posting, access, and monitoring requirements for the affected areas should be implemented. Plant operating and surveillance proce-dures should be revised, as required, to minimize the time and number of personnel required in radiation areas for operations, maintenance, in-service inspection, etc. 6.1.3.3 Plant Shielding. The radiological survey of subsection 6.1.3.2 should be used to determine the adequacy of existing plant shielding. In addition, the radiation levels from senple lines, sample coolers and monitoring equipment may increase due to HWC and should be checked for adequate shielding. If required, measures for selective upgrading of plant shielding should be implemented to reduce both work area and site boundary dose rates. 6.1.3.4 Maintenance Activities. Hydrogen water chmistry will have minimum impact on occupational exposures resulting from maintenance activities. Plant procedures should incorporate appropriate requirements for access to and monitor-ing of areas where increased dose rates exist with HWC to satisfy ALARA require-ments. For extended maintenance, plant procedures should include provisions to terminate the hydrogen injection. Due to the short half-life of N-16, radiation levels will return to pre-HWC conditions within minutes of hydrogen shutoff. 6.1.3.5 Radiolonical Surveillance proarams. Oose rate surveys should be conducted and radiation levels should be monitored pertoeically to ensure compliance with the radiological limits imposed by 40 WR Part 190,10 WR part 100, and 10 CFR Part 20. Additional surveys may be required to emply with ALARA requir'esents. 6.1.3.6 Measurement of N-16 Radiation. The radiological surveiller.6e program should includt special provisions for N-16 surveys. Selection of appropriate health ptysics instrumentation and application of correction factors are required to provide accurate dose measurements. (Thiscorrectionisrequiredduetothe 6-3

e effect of the energenic N-16 gamma on instrumentation calibrated with less energenic gamma sources.) All plant survey meters should be reviewed and appropriate calibration and correction methods accounted for in plant procedures. A review of the plant personnel dosimetry program shall be conducted to ensure that the appropriate cailbration or correction factors are used in areas when significant N-16 radiation is present. 6.1.3.7 Value/ Impact Considerations. The following discussion reviews the total dose impact on a plant which implements HWC. A radiological assessment at Dresden indicates that the total dose increase with HWC is approximately 0.5% on an annual basis (1935 to 1945 man-rem / year) (Ref.6-1). While this increase is site dependent due to plant layout and shield-ing configurations, significant variances from the Dresden assessment are not anticipated. Thus, over the life of a plant (assuming a 25-year remaining life), the projected total dose increase with HWC is f250-300 man-rems. With HWC implementation, the potential exists to relax current augrrented in-service inspection requirements imposed by NRC Generic Letter 84-11 (Ref. 6-2) and elimination of extended plant outages for pipe replacement and/or repair. The value/ impact assessment presented in Appendix E to Ref. 6-3 projects a 1161 man-rem (best estimate) savings over the life of the plant as a consequence of reduced inspections and repairs with HWC. Typical pipe replacement projects result in a total dose of 1400 to 2000 man-rem. Thus, HWC implementation could result in a significant savings in total dose over the life of the plant. 6.1.4 Water Chemistry Control Procedures should be developed to maintain the high reactor water quality necessary to obtain the maximum benefit from the HWC system. The EPRI-BWR Owners Group has developed 'BWR Water Chemistry Guidelines" which should be used in developing these proceduros (Reference 6-4). 6.1.5 Fuel Survet11ance Program No significan,t effect of hydrogen irdection on fuel perfonnance has been observed nor is expecttd. However, since in-reactor experience with hydrogen water chemistry is limited, utilities should consider the fuel surveillance programs recunmended by their fuel suppliers. 6-4

,a I t i 6.2 MAINTENANCE A preventative maintenance program should be developed and instituted to ensure proper equipment perforvence to reduce unscheduled repairs.,All maintenance activities should be carefully planned to reduce interference with station oper-I ation, assure industrial safety, and minimize maintenance personnel exposure. Written procedures should be developed and followed Jn the perfomance of main-They should be written with the objective of protecting plant tenance work. personnel fra physical harm, radiation exposure and to reduce hydrogen addition Radiation exposure should be reduced by shortening the time system downtime. required in a high radiation field and by reducing its intensity by turning off i the HWC system or other means prior to maintenance. 6.3 TRAINING In order for the HWC syste to maintain its syste integrity and to provide the The most expected benefits from its use, the system must be operated correctly. effective means of reducing the potential of operator error is through proper training. Training should be provided to: i 1. Instruct operators on the function, theory and operating 1 characteristics of the system and all its major system components; Advise operators of the consequences of component malfunctions 2. and misoperation and provide instruction as to appropriate corrective actions to be taken; 3. Advise operations and maintenance personnel of the potential - and provide instruction as to hazards of gases in the systen appropriate procedures for theIr handling; Instruct emergency response personnel on appropriate procedures 4. or 0 for handling fires or personnel injuries involving H2 2 i liquid and gases. Instruct plant personnel on the expected radiation changes due 5. l to the operation of the HWC system and the appropriate ALARA practices to be taken to ministre dose.

• j 6.

Instfuct appropriate personnel on the benefits of HWC. J Advise maintenance and construction personnel of the routing of 7. hydrogen lines and of the appropriate protective actions to be taken when working near these lines. 6-5 A ]

4 Periodic training should be provided to reinforce information described above and to communicate information regarding any modifications, procedural changes, or incidents. 6.4 IDENTIFICATION In order to aid plant personnel in identifying hydrogen and oxygen lines, these lines should be color coded as required by ANSI-Z 35.1.

6.5 REFERENCES

" EPRI Hydrogen Water " Environmental Impact of Hydrogen Water Chemistry $4. 6-1 Chemistry Workshop Atlanta, Georgia, December 19 "Inpsection of BWR Stainless Steel Piping," NRC Generic Letter 84-11, 6-2 April 19, 1984. " Report of the United States Nuclear Regulatory Commission Piping Review 6-3 Committee," NUREG-1061 Volume 1 August 1984. 6-4 '"BWR Water Chemistry Guidelines," EPRI Report NP-3589-SR-LD, Apri,1 1985. i e O e 6-6

Section 7 SURVElLLANCE AND TESTING 7.1 SYSTEM INTEGRITY TESTING In addition to the testing required by the applicable design codes, completed process systems which will contain hydrogen shall be leak tested with helium prior to initial operation of the system. All components and joints shall be so tested in the fabrication shop or after installation, as appropriate. Appropriate helium leak tests shall be performed on portions of the system following any modifications or maintenance activity which could affect the pressure boundary of the system. l 7.2 PREOPERATIONAL AND PERIODIC TESTING Completed systems should be tested to the extent practicable to verify the operability and functional perfomance of the systen. Proper functioning of the I following items should be verified: 1. Trip and alarm functions per Table 2-2 2. Gas purity, if generated on site 3. Safety features i 4. Excess flow check valves 5. System controls and monitors per Table 2-2. t A program should be developed for periodic retesting to verify the operability and the functional perfomance of the systen. i e 7-1

l Section 8 RADIATION ENITORING

8.1 INTRODUCTION

This section reviews the radiological consequence of hydrogen water chem (HWC) and presents the basis for increasing the main steam line r It is concluded that implementation of HWC does not setpoint to accommodate HWC. reduce the margin of safety as defined in the basis of the technical sp setpoint. During nomal operation of a BWR, nitrogen-16 is fomed from an ox N-16 decays with a half-life of 7.1 seconds and emits a high-energy reaction. Normally, most of the N-16 combines rapidly with oxygen gamma photon (6.1 MeV). However, because of the to form water-soluble, nonvolatile nitrates and nitrites. lower oxidizing potential present in a hydrogen water chmistry environment, l As a conse-higher percentage of the N-16 is converted to more volatile species. quence, the steam activity during hydrogen addition is in:reased a f The dose rates in the turbine building, plant environs, and off site to five. also increase; however, the magnitude of the increase at any given location depends upon the contribution of the steam activity to the total dose location. The specific concerns include: The dose to members of the general public (40 CFR 190), 1. The dose to personnel in unrestricted areas (10 CFR 20), and 2. The maintenance of personnel exposure "as low as reasonably 3. achievable" (ALARA). MAIN ShEAM LINE RADIATION ENITORING 8.2 As noted in the previous section, the main steam line radiation will incre The majority of BWRs have a technical i to 5-fold with hydrogen water chemistry. specification requirement for the main steam line radiation monitor setpoint that is less than or equal to three (3) times the normal rated For these plants an adjustment in the MSLRM setpoint is required to background. For earlier BWRs with MSLRM setpoints of allow operation with hydrogen injection. 8 I .a

seven (7) to ten (10) times nomal full power background, a set point change may not be required. 8.2.1 Dual MSLRM Setpoint Recommendation For plants at which credit is taken for En MSLRM-initiated isolation in the Above control rod drop accident (CRDA), a dual setpoint approach may be utilized. 20% rated power the setpoint should be readjusted to 3 times the nomal rated full power background with hydrogen addition. Below 20% rated power or the power level required by the FSAR or technical specifications (see Table 2-1), the existing setpoint is maintained and hydrogen should not be injected into the feedwater If an unanticipated power reduction event occurs such that the reactor system. power is below this power level without the required setpoint change, control rod At motion should be suspended until the necessary setpoint adjustment is made. newer plants, credit is not taken for an MSLRM-initiated isolation after a CRDA, and a dual set point is not needed at these plants. 8.2.2 MSLRM Safety Design Basis The only event for which some plants may take credit for main steam isolation valve (MSIV) closure on main steam line high radiation is the design basis control rod drop accident (CRDA). As documented in Ref. 8-1, the CRDA is only of concern below 10% of rated power. Above this power level the rod worths and resultant CRDA peak fuel enthalpies are not limiting due to core voids and faster Doppler feedback. Since the current MSLRM setpoint will not be changed below 20% rated power, the MSLRM sensitivity to fuel failure is not impacted and the FSAR analysis I for the CRDA remains valid. The licensing basis for the CRDA states that the maximum control rod worth is j established by assuming the worst single inadvertent operator error (8-2). From l Refs. 8-2 and 8-3, the maximum control rod worth above 20% rated power, assuming a single operator error, is <0.8% W/K. Parametric studies utilizing the conservative GE excursion model (Ref. 8-1) indicate that the maximum peak fuel enthalpy for a dropped control rod worth of 0.8% W/K is less than 120 calories pergram(Ref.8-3). Consequently, the conservatively calculated peak fuel enthalpy for a CRDA above 20% rated power will have significant margin to the fuel - cladding failure threshold of 170 calories per gram. An increase in the MSLRM setpoint will not impact any other FSAR accident or transient analysis since no credit is taken for this isolation signal. 8-2

Consequently, a technical specification change which adopts the recommended dual setpoint approach will not reduce overall plant safety margins. 8.2.3 MSLRM Sensitivity Conceptually, the sensitivity of the MSLRM to fission products is effectively reduced by the. increase in the setpoint above 20% power. However, it is still functional and capable of initiating a reactor scram. The main function of the instrument is to help maintain offsite releases to within the applicable regulatory limits. The MSLRM is supplemented by the offgas radiation monitoring , system which monitors the gaseous effluent prior to its discharge to the environs. The offgas radiation. monitor setpoint is established to help ensure that the equivalent stack release limit is not exceeded. 8.2.4 Conclusions Fran the above discussion, it can be concluded that an increase in the MSLRM setpoint above 20% rale'd power does-not reduce the safety margins as defined by technical specifications and the offsite radiological effects as a consequence of design base accidents do not exceed 10.CFR Part 100 limits. Furthermore, since this change to the MSLRM can be justified independent of HWC, this change does not result in an unreviewed safety concern. t l 8.3 EQUIPMENT QUALIFICATION Outside primary contaiment the increase in dose rates with HWC is relatively small relative to the integrated dose assumed for equipment qualification (EQ) i tests. Furthemore, dose rates inside the drywell will decrease because of the f increased carryover of N-16 in the steam. Each utility should review the l resultant dose increases to ensure that the doses assumed in the EQ test required of electrical equipment per 10CFR Part 50.49 remain bounding. I i l I i l 8-3

4

8.4 REFERENCES

R. C. Stirn et al., Rod Drop Analysis for Large Boiling Water Reactors, 8-1 General Electric Company, March 1972 (NEDO-10527). R. C. Stirn et al., Rod Drop Accident Analysis for Lanje' Boiling Water 8-2 Reactors Addendum No. 2 Exposed Cores, General Electric Company, January 1973 (NE00-10527, Supplement 2). R. C. Stirn et al., Rod Drop Accident AnalysisTor Large Boiling Water 8-3 Reactors Addendum No.1 Multiple Enrichment Cores With Axial Gadolinium, General Electric Company, July 1972 (NEDO-10527, Supplement 1). i. e e 4 i f 8-4 i .}}